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Sample records for biologically tunable material

  1. Acetalated dextran is a chemically and biologically tunable material for particulate immunotherapy.

    Science.gov (United States)

    Broaders, Kyle E; Cohen, Joel A; Beaudette, Tristan T; Bachelder, Eric M; Fréchet, Jean M J

    2009-04-07

    Materials that combine facile synthesis, simple tuning of degradation rate, processability, and biocompatibility are in high demand for use in biomedical applications. We report on acetalated dextran, a biocompatible material that can be formed into microparticles with degradation rates that are tunable over 2 orders of magnitude depending on the degree and type of acetal modification. Varying the degradation rate produces particles that perform better than poly(lactic-co-glycolic acid) and iron oxide, two commonly studied materials used for particulate immunotherapy, in major histocompatibility complex class I (MHC I) and MHC II presentation assays. Modulating the material properties leads to antigen presentation on MHC I via pathways that are dependent or independent of the transporter associated with antigen processing. To the best of our knowledge, this is the only example of a material that can be tuned to operate on different immunological pathways while maximizing immunological presentation.

  2. Tunable structural color in organisms and photonic materials for design of bioinspired materials.

    Science.gov (United States)

    Fudouzi, Hiroshi

    2011-12-01

    In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  3. Tunable structural color in organisms and photonic materials for design of bioinspired materials

    Directory of Open Access Journals (Sweden)

    Hiroshi Fudouzi

    2011-01-01

    Full Text Available In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  4. Electrically tunable materials for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Aftab, E-mail: aahmed@anl.gov; Goldthorpe, Irene A.; Khandani, Amir K. [Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-03-15

    Microwave devices based on tunable materials are of vigorous current interest. Typical applications include phase shifters, antenna beam steering, filters, voltage controlled oscillators, matching networks, and tunable power splitters. The objective of this review is to assist in the material selection process for various applications in the microwave regime considering response time, required level of tunability, operating temperature, and loss tangent. The performance of a variety of material types are compared, including ferroelectric ceramics, polymers, and liquid crystals. Particular attention is given to ferroelectric materials as they are the most promising candidates when response time, dielectric loss, and tunability are important. However, polymers and liquid crystals are emerging as potential candidates for a number of new applications, offering mechanical flexibility, lower weight, and lower tuning voltages.

  5. Tunable promoters in systems biology

    DEFF Research Database (Denmark)

    Mijakovic, Ivan; Petranovic, Dina; Jensen, Peter Ruhdal

    2005-01-01

    The construction of synthetic promoter libraries has represented a major breakthrough in systems biology, enabling the subtle tuning of enzyme activities. A number of tools are now available that allow the modulation of gene expression and the detection of changes in expression patterns. But, how...... does one choose the correct promoter and what are the appropriate methods for reading promoter strength? Furthermore, how fine should the tuning of gene expression be for some specific applications and how can the simultaneous and individual tuning of multiple genes be achieved? Some recent studies...

  6. Tunable promoters in synthetic and systems biology

    DEFF Research Database (Denmark)

    Dehli, Tore; Solem, Christian; Jensen, Peter Ruhdal

    2012-01-01

    in synthetic biology. A number of tools exist to manipulate the steps in between gene sequence and functional protein in living cells, but out of these the most straight-forward approach is to alter the gene expression level by manipulating the promoter sequence. Some of the promoter tuning tools available......Synthetic and systems biologists need standardized, modular and orthogonal tools yielding predictable functions in vivo. In systems biology such tools are needed to quantitatively analyze the behavior of biological systems while the efficient engineering of artificial gene networks is central...... for accomplishing such altered gene expression levels are discussed here along with examples of their use, and ideas for new tools are described. The road ahead looks very promising for synthetic and systems biologists as tools to achieve just about anything in terms of tuning and timing multiple gene expression...

  7. Multiscale Biological Materials

    DEFF Research Database (Denmark)

    Frølich, Simon

    example of biological design. We investigated the architecture of A. simplex and found that an advanced hierarchical biomineralized structure acts as the interface between soft musculature and a stiff substrate, thus securing underwater attachment. In bone, the mechanical properties of the material......, and the nanoscale response of bone in compression. Lastly, a framework for the investigation of biological design principles has been developed. The framework combines parametric modeling, multi-material 3D-printing, and direct mechanical testing to efficiently screen large parameter spaces of biological design. We......Materials formed by organisms, also known as biological materials, exhibit outstanding structural properties. The range of materials formed in nature is remarkable and their functions include support, protection, motion, sensing, storage, and maintenance of physiological homeostasis. These complex...

  8. Tunable Dielectric Materials and Devices for Broadband Wireless Communications

    Science.gov (United States)

    Mueller, Carl H.; Miranda, Felix A.; Dayton, James A. (Technical Monitor)

    1998-01-01

    Wireless and satellite communications are a rapidly growing industries which are slated for explosive growth into emerging countries as well as countries with advanced economies. The dominant trend in wireless communication systems is towards broadband applications such as multimedia file transfer, video transmission and Internet access. These applications require much higher data transmission rates than those currently used for voice transmission applications. To achieve these higher data rates, substantially larger bandwidths and higher carrier frequencies are required. A key roadblock to implementing these systems at K-band (18-26.5 GHz) and Ka-band (26.5-40 GHz) is the need to develop hardware which meets the requirements for high data rate transmission in a cost effective manner. In this chapter, we report on the status of tunable dielectric thin films for devices, such as resonators, filters, phased array antennas, and tunable oscillators, which utilize nonlinear tuning in the control elements. Paraelectric materials such as Barium Strontium Titanate ((Ba, Sr)TiO3) have dielectric constants which can be tuned by varying the magnitude of the electric field across the material. Therefore, these materials can be used to control the frequency and/or phase response of various devices such as electronically steerable phased array antennas, oscillators, and filters. Currently, tunable dielectric devices are being developed for applications which require high tunability, low loss, and good RF power-handling capabilities at microwave and millimeter-wave frequencies. These properties are strongly impacted by film microstructure and device design, and considerable developmental work is still required. However, in the last several years enormous progress has occurred in this field, validating the potential of tunable dielectric technology for broadband wireless communication applications. In this chapter we summarize how film processing techniques, microwave test

  9. Biomimetic photonic materials with tunable structural colors.

    Science.gov (United States)

    Xu, Jun; Guo, Zhiguang

    2013-09-15

    Nature is a huge gallery of art involving nearly perfect structures and forms over the millions of years developing. Inspiration from natural structures exhibiting structural colors is first discussed. We give some examples of natural one-, two-, and three-dimensional photonic structures. This review article presents a brief summary of recent progress on bio-inspired photonic materials with variable structural colors, including the different facile and efficient routes to construct the nano-architectures, and the development of the artificial variable structural color photonic materials. Besides the superior optical properties, the excellent functions such as robust mechanical strength, good wettability are also mentioned, as well as the technical importance in various applications. This review will provide significant insight into the fabrication, design and application of the structural color materials.

  10. Nanoscale Tunable Strong Carrier Density Modulation of 2D Materials for Metamaterials and Other Tunable Optoelectronics

    Science.gov (United States)

    Peng, Cheng; Efetov, Dmitri; Shiue, Ren-Jye; Nanot, Sebastien; Hempel, Marek; Kong, Jing; Koppens, Frank; Englund, Dirk

    Strong spatial tunability of the charge carrier density at nanoscale is essential to many 2D-material-based electronic and optoelectronic applications. As an example, plasmonic metamaterials with nanoscale dimensions would make graphene plasmonics at visible and near-infrared wavelengths possible. However, existing gating techniques based on conventional dielectric gating geometries limit the spatial resolution and achievable carrier concentration, strongly restricting the available wavelength, geometry, and quality of the devices. Here, we present a novel spatially selective electrolyte gating approach that allows for in-plane spatial Fermi energy modulation of 2D materials of more than 1 eV (carrier density of n = 1014 cm-2) across a length of 2 nm. We present electrostatic simulations as well as electronic transport, photocurrent, cyclic voltammetry and optical spectroscopy measurements to characterize the performance of the gating technique applied to graphene devices. The high spatial resolution, high doping capacity, full tunability and self-aligned device geometry of the presented technique opens a new venue for nanoscale metamaterial engineering of 2D materials for complete optical absorption, nonlinear optics and sensing, among other applications.

  11. Flotation of Biological Materials

    Directory of Open Access Journals (Sweden)

    George Z. Kyzas

    2014-03-01

    Full Text Available Flotation constitutes a gravity separation process, which originated from the minerals processing field. However, it has, nowadays, found several other applications, as for example in the wastewater treatment field. Concerning the necessary bubble generation method, typically dispersed-air or dissolved-air flotation was mainly used. Various types of biological materials were tested and floated efficiently, such as bacteria, fungi, yeasts, activated sludge, grape stalks, etc. Innovative processes have been studied in our Laboratory, particularly for metal ions removal, involving the initial abstraction of heavy metal ions onto a sorbent (including a biosorbent: in the first, the application of a flotation stage followed for the efficient downstream separation of metal-laden particles. The ability of microorganisms to remove metal ions from dilute aqueous solutions (as most wastewaters are is a well-known property. The second separation process, also applied effectively, was a new hybrid cell of microfiltration combined with flotation. Sustainability in this field and its significance for the chemical and process industry is commented.

  12. Nanocontainers made of Various Materials with Tunable Shape and Size

    Science.gov (United States)

    Zhao, Xianglong; Meng, Guowen; Han, Fangming; Li, Xiangdong; Chen, Bensong; Xu, Qiaoling; Zhu, Xiaoguang; Chu, Zhaoqin; Kong, Mingguang; Huang, Qing

    2013-07-01

    Nanocontainers have great potentials in targeted drug delivery and nanospace-confined reactions. However, the previous synthetic approaches exhibited limited control over the morphology, size and materials of the nanocontainers, which are crucial in practical applications. Here, we present a synthetic approach to multi-segment linear-shaped nanopores with pre-designed morphologies inside anodic aluminium oxide (AAO), by tailoring the anodizing duration after a rational increase of the applied anodizing voltage and the number of voltage increase during Al foil anodization. Then, we achieve nanocontainers with designed morphologies, such as nanofunnels, nanobottles, nano-separating-funnels and nanodroppers, with tunable sizes and diverse materials of carbon, silicon, germanium, hafnium oxide, silica and nickel/carbon magnetic composite, by depositing a thin layer of materials on the inner walls of the pre-designed AAO nanopores. The strategy has far-reaching implications in the designing and large-scale fabrication of nanocontainers, opening up new opportunities in nanotechnology applications.

  13. Peptide Nanotube Reinforced Polymers: A System for Tunable, Composite Materials

    Science.gov (United States)

    2015-11-30

    Large scale material production (biofilm paint, spray-on coatings , self-standing 3D materials) •  Environmental responsiveness (sensing...applications BIOFUEL PRODUCTION WATER PURIFICATION CELL CAPTURE/ AFFINITY SEPARATIONS PROTECTIVE COATINGS BIO-ELECTRODE INTERFACE BIOSENSING DECONTAMINATION...them. (Recombinant DNA Technology) Cohen, Boyer, and Lobban 3% We understand how they work… ( Antibiotics , Microbiology, Molecular Biology

  14. Making Biological Materials

    Institute of Scientific and Technical Information of China (English)

    Julian F.V.Vincent

    2005-01-01

    @@ 1 Chemistry and synthesis 1.1 Production and control of materials These days there can be few people who do not know that proteins are defined by DNA. DNA is made of two strands, each of which has along it, like a string of fairy lights, side branches that meet between the strands and hold them together.

  15. Tunable states of interlayer cations in two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Numata, K. [Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Dai, W. [Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071 (China); Hunger, M. [Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart (Germany)

    2014-03-31

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of {sup 23}Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and {sup 23}Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed.

  16. Artful interfaces within biological materials

    Directory of Open Access Journals (Sweden)

    John W.C. Dunlop

    2011-03-01

    Full Text Available Biological materials have a wide range of mechanical properties matching their biological function. This is achieved via complex structural hierarchies, spanning many length scales, arising from the assembly of different sized building blocks during growth. The interfaces between these building blocks can increase resistance to fracture, join materials of different character, make them deform more easily and provide motility. While they represent only a tiny fraction of the overall volume, interfaces are essential for the integrity and function of the overall tissue. Understanding their construction principles, often based on specialized molecular assemblies, may change our current thinking about composite materials.

  17. Biological materials: a materials science approach.

    Science.gov (United States)

    Meyers, Marc A; Chen, Po-Yu; Lopez, Maria I; Seki, Yasuaki; Lin, Albert Y M

    2011-07-01

    The approach used by Materials Science and Engineering is revealing new aspects in the structure and properties of biological materials. The integration of advanced characterization, mechanical testing, and modeling methods can rationalize heretofore unexplained aspects of these structures. As an illustration of the power of this methodology, we apply it to biomineralized shells, avian beaks and feathers, and fish scales. We also present a few selected bioinspired applications: Velcro, an Al2O3-PMMA composite inspired by the abalone shell, and synthetic attachment devices inspired by gecko.

  18. Band structures tunability of bulk 2D phononic crystals made of magneto-elastic materials

    Directory of Open Access Journals (Sweden)

    J. O. Vasseur

    2011-12-01

    Full Text Available The feasibility of contactless tunability of the band structure of two-dimensional phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. The influence of the amplitude and of the orientation with respect to the inclusion axis of the applied magnetic field are studied in details. Applications to tunable selective frequency filters with switching functionnality and to reconfigurable wave-guides and demultiplexing devices are then discussed.

  19. Multistep phosphorylation systems: tunable components of biological signaling circuits.

    Science.gov (United States)

    Valk, Evin; Venta, Rainis; Ord, Mihkel; Faustova, Ilona; Kõivomägi, Mardo; Loog, Mart

    2014-11-05

    Multisite phosphorylation of proteins is a powerful signal processing mechanism that plays crucial roles in cell division and differentiation as well as in disease. We recently demonstrated a novel phenomenon in cell cycle regulation by showing that cyclin-dependent kinase-dependent multisite phosphorylation of a crucial substrate is performed sequentially in the N-to-C terminal direction along the disordered protein. The process is controlled by key parameters, including the distance between phosphorylation sites, the distribution of serines and threonines in sites, and the position of docking motifs. According to our model, linear patterns of phosphorylation along disordered protein segments determine the signal-response function of a multisite phosphorylation switch. Here we discuss the general advantages and engineering principles of multisite phosphorylation networks as processors of kinase signals. We also address the idea of using the mechanistic logic of linear multisite phosphorylation networks to design circuits for synthetic biology applications.

  20. Tunable ferroelectric meta-material phase shifter embedded inside low temperature co-fired ceramics (LTCC)

    Science.gov (United States)

    Tork, Hossam S.

    This dissertation describes electrically tunable microwave devices utilizing low temperature co-fired ceramics (LTCC) and thick film via filled with the ferroelectric materials barium strontium titanate (BST) and barium zirconate titanate (BZT). Tunable ferroelectric capacitors, zero meta-material phase shifters, and tunable meta-material phase shifters are presented. Microwave phase shifters have many applications in microwave devices. They are essential components for active and passive phased array antennas and their most common use is in scanning phased array antennas. They are used in synthetic aperture radars (SAR), low earth orbit (LEO) communication satellites, collision warning radars, and intelligent vehicle highway systems (IVHS), in addition to various other applications. Tunable ferroelectric materials have been investigated, since they offer the possibility of lowering the total cost of phased arrays. Two of the most promising ferroelectric materials in microwave applications are BST and BZT. The proposed design and implementation in this research introduce new types of tunable meta-material phase shifters embedded inside LTCC, which use BST and BZT as capacitive tunable dielectric material controlled by changing the applied voltage. This phase shifter has the advantages of meta-material structures, which produce little phase error and compensation while having the simultaneous advantage of using LTCC technology for embedding passive components that improve signal integrity (several signal lines, power planes, and ground planes) by using different processes like via filling, screen printing, laminating and firing that can be produced in compact sizes at a low cost. The via filling technique was used to build tunable BST, BZT ferroelectric material capacitors to control phase shift. Finally, The use of the proposed ferroelectric meta-material phase shifter improves phase shifter performance by reducing insertion loss in both transmitting and receiving

  1. Oxygen Sensing Difluoroboron β-Diketonate Polylactide Materials with Tunable Dynamic Ranges for Wound Imaging.

    Science.gov (United States)

    DeRosa, Christopher A; Seaman, Scott A; Mathew, Alexander S; Gorick, Catherine M; Fan, Ziyi; Demas, James N; Peirce, Shayn M; Fraser, Cassandra L

    2016-11-23

    Difluoroboron β-diketonate poly(lactic acid) materials exhibit both fluorescence (F) and oxygen sensitive room-temperature phosphorescence (RTP). Introduction of halide heavy atoms (Br and I) is an effective strategy to control the oxygen sensitivity in these materials. A series of naphthyl-phenyl (nbm) dye derivatives with hydrogen, bromide and iodide substituents were prepared for comparison. As nanoparticles, the hydrogen derivative was hypersensitive to oxygen (0-0.3%), while the bromide analogue was suited for hypoxia detection (0-3% O2). The iodo derivative, BF2nbm(I)PLA, showed excellent F to RTP peak separation and an 0-100% oxygen sensitivity range unprecedented for metal-free RTP emitting materials. Due to the dual emission and unconventionally long RTP lifetimes of these O2 sensing materials, a portable, cost-effective camera was used to quantify oxygen levels via lifetime and red/green/blue (RGB) ratiometry. The hypersensitive H dye was well matched to lifetime detection, simultaneous lifetime and ratiometric imaging was possible for the bromide analogue, whereas the iodide material, with intense RTP emission and a shorter lifetime, was suited for RGB ratiometry. To demonstrate the prospects of this camera/material design combination for bioimaging, iodide boron dye-PLA nanoparticles were applied to a murine wound model to detect oxygen levels. Surprisingly, wound oxygen imaging was achieved without covering (i.e. without isolating from ambient conditions, air). Additionally, would healing was monitored via wound size reduction and associated oxygen recovery, from hypoxic to normoxic. These single-component materials provide a simple tunable platform for biological oxygen sensing that can be deployed to spatially resolve oxygen in a variety of environments.

  2. Liquid-crystal photonic-band-gap materials the tunable electromagnetic vacuum

    CERN Document Server

    Busch, K

    1999-01-01

    We demonstrate that when an optically birefringent nematic liquid crystal is infiltrated into the void regions of an inverse opal, photonic-band-gap (PBG) material, the resulting composite material exhibits a completely tunable PBG. $9 In particular, the three- dimensional PBG can be completely opened or closed by applying an electric field which rotates the axis of the nematic molecules relative to the inverse opal backbone. Tunable light localization effects may $9 be realized by controlling the orientational disorder in the nematic. (28 refs).

  3. Bioinspired materials: Boosting plant biology

    Science.gov (United States)

    Scholes, Gregory D.; Sargent, Edward H.

    2014-04-01

    Chloroplasts with extended photosynthetic activity beyond the visible absorption spectrum, and living leaves that perform non-biological functions, are made possible by localizing nanoparticles within plant organelles.

  4. [Biological material sampling for atomic absorption analysis].

    Science.gov (United States)

    Makarenko, N P; Ganebnykh, E V

    2007-01-01

    The optimum conditions have been chosen for mineralization of biological material for the atomic absorption determination of toxic metals, by using a [Russian characters: see text]-01 laboratory furnace (Gefest) upon exposure to high temperature, pressure, and microwave field. The completeness of dissection of biological material by microwave mineralization is shown under the optimal conditions.

  5. Tunable thermal expansion in framework materials through redox intercalation.

    Science.gov (United States)

    Chen, Jun; Gao, Qilong; Sanson, Andrea; Jiang, Xingxing; Huang, Qingzhen; Carnera, Alberto; Rodriguez, Clara Guglieri; Olivi, Luca; Wang, Lei; Hu, Lei; Lin, Kun; Ren, Yang; Lin, Zheshuai; Wang, Cong; Gu, Lin; Deng, Jinxia; Attfield, J Paul; Xing, Xianran

    2017-02-09

    Thermal expansion properties of solids are of fundamental interest and control of thermal expansion is important for practical applications but can be difficult to achieve. Many framework-type materials show negative thermal expansion when internal cages are empty but positive thermal expansion when additional atoms or molecules fill internal voids present. Here we show that redox intercalation offers an effective method to control thermal expansion from positive to zero to negative by insertion of Li ions into the simple negative thermal expansion framework material ScF3, doped with 10% Fe to enable reduction. The small concentration of intercalated Li ions has a strong influence through steric hindrance of transverse fluoride ion vibrations, which directly controls the thermal expansion. Redox intercalation of guest ions is thus likely to be a general and effective method for controlling thermal expansion in the many known framework materials with phonon-driven negative thermal expansion.

  6. Tunable Optical Sources and Synthetic Nonlinear Media: Growth and Characterization of Nonlinear Optical Materials

    Science.gov (United States)

    1992-02-13

    niobate and absolute measurements of nonlinear optical coefficients of six different commonly used nonlinear optical materials. The refractometry data for...applied radiation and is now an established technology for Nd:YAG lasers. Optical parametric oscillation and amplification provide a method of generating...continuously tunable output -3- The relative advantages of nonlinear optical frequency conversion compared to other methods for the generation of near

  7. Evaluation of the Biological Effects of Externally Tunable, Hydrogel Encapsulated Quantum Dot Nanospheres in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Somesree GhoshMitra

    2011-08-01

    Full Text Available Quantum Dots (QDs have become an interesting subject of study for labeling and drug delivery in biomedical research due to their unique responses to external stimuli. In this paper, the biological effects of a novel hydrogel based QD nano-structure on E. coli bacteria are presented. The experimental evidence reveals that cadmium telluride (CdTe QDs that are encapsulated inside biocompatible polymeric shells have reduced or negligible toxicity to this model cell system, even when exposed at higher dosages. Furthermore, a preliminary gene expression study indicates that QD-hydrogel nanospheres do not inhibit the Green Fluorescent Protein (GFP gene expression. As the biocompatible and externally tunable polymer shells possess the capability to control the QD packing density at nanometer scales, the resulting luminescence efficiency of the nanostructures, besides reducing the cytotoxic potential, may be suitable for various biomedical applications.

  8. Dynamic Control of Radiative Heat Transfer with Tunable Materials for Thermal Management in Both Far and Near Fields

    Science.gov (United States)

    Yang, Yue

    The proposed research mainly focuses on employing tunable materials to achieve dynamic control of radiative heat transfer in both far and near fields for thermal management. Vanadium dioxide (VO2), which undergoes a phase transition from insulator to metal at the temperature of 341 K, is one tunable material being applied. The other one is graphene, whose optical properties can be tuned by chemical potential through external bias or chemical doping. (Abstract shortened by ProQuest.).

  9. Transition metal chalcogenides: ultrathin inorganic materials with tunable electronic properties.

    Science.gov (United States)

    Heine, Thomas

    2015-01-20

    CONSPECTUS: After the discovery of graphene and the development of powerful exfoliation techniques, experimental preparation of two-dimensional (2D) crystals can be expected for any layered material that is known to chemistry. Besides graphene and hexagonal boron nitride (h-BN), transition metal chalcogenides (TMC) are among the most studied ultrathin materials. In particular, single-layer MoS2, a direct band gap semiconductor with ∼1.9 eV energy gap, is popular in physics and nanoelectronics, because it nicely complements semimetallic graphene and insulating h-BN monolayer as a construction component for flexible 2D electronics and because it was already successfully applied in the laboratory as basis material for transistors and other electronic and optoelectronic devices. Two-dimensional crystals are subject to significant quantum confinement: compared with their parent layered 3D material, they show different structural, electronic, and optical properties, such as spontaneous rippling as free-standing monolayer, significant changes of the electronic band structure, giant spin-orbit splitting, and enhanced photoluminescence. Most of those properties are intrinsic for the monolayer and already absent for two-layer stacks of the same 2D crystal. For example, single-layer MoS2 is a direct band gap semiconductor with spin-orbit splitting of 150 meV in the valence band, while the bilayer of the same material is an indirect band gap semiconductor without observable spin-orbit splitting. All these properties have been observed experimentally and are in excellent agreement with calculations based on density-functional theory. This Account reports theoretical studies of a subgroup of transition metal dichalcogenides with the composition MX2, with M = Mo, or W and X = Se or S, also referred to as "MoWSeS materials". Results on the electronic structure, quantum confinement, spin-orbit coupling, spontaneous monolayer rippling, and change of electronic properties in the

  10. Voltage tunability of thermal conductivity in ferroelectric materials

    Science.gov (United States)

    Ihlefeld, Jon; Hopkins, Patrick Edward

    2016-02-09

    A method to control thermal energy transport uses mobile coherent interfaces in nanoscale ferroelectric films to scatter phonons. The thermal conductivity can be actively tuned, simply by applying an electrical potential across the ferroelectric material and thereby altering the density of these coherent boundaries to directly impact thermal transport at room temperature and above. The invention eliminates the necessity of using moving components or poor efficiency methods to control heat transfer, enabling a means of thermal energy control at the micro- and nano-scales.

  11. Tetravalent chromium doped laser materials and NIR tunable lasers

    Science.gov (United States)

    Alfano, Robert R. (Inventor); Petricevic, Vladimir (Inventor); Bykov, Alexey (Inventor)

    2008-01-01

    A method is described to improve and produce purer Cr.sup.4+-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr.sup.3+, Cr.sup.2+, Cr.sup.5+, and Cr.sup.6+. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr.sup.4+:Ca.sub.2GeO.sub.4, Cr.sup.4+:Ca.sub.2SiO.sub.4, Cr.sup.4+:Ca.sub.2Ge.sub.xSi.sub.1-xO.sub.4 (where 0NIR laser applications.

  12. Tunable electronic and magnetic properties of two‐dimensional materials and their one‐dimensional derivatives

    Science.gov (United States)

    Zhang, Zhuhua; Liu, Xiaofei; Yu, Jin; Hang, Yang; Li, Yao; Guo, Yufeng; Xu, Ying; Sun, Xu; Zhou, Jianxin

    2016-01-01

    Low‐dimensional materials exhibit many exceptional properties and functionalities which can be efficiently tuned by externally applied force or fields. Here we review the current status of research on tuning the electronic and magnetic properties of low‐dimensional carbon, boron nitride, metal‐dichalcogenides, phosphorene nanomaterials by applied engineering strain, external electric field and interaction with substrates, etc, with particular focus on the progress of computational methods and studies. We highlight the similarities and differences of the property modulation among one‐ and two‐dimensional nanomaterials. Recent breakthroughs in experimental demonstration of the tunable functionalities in typical nanostructures are also presented. Finally, prospective and challenges for applying the tunable properties into functional devices are discussed. WIREs Comput Mol Sci 2016, 6:324–350. doi: 10.1002/wcms.1251 For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article. PMID:27818710

  13. Liquid Crystalline Materials for Biological Applications.

    Science.gov (United States)

    Lowe, Aaron M; Abbott, Nicholas L

    2012-03-13

    Liquid crystals have a long history of use as materials that respond to external stimuli (e.g., electrical and optical fields). More recently, a series of investigations have reported the design of liquid crystalline materials that undergo ordering transitions in response to a range of biological interactions, including interactions involving proteins, nucleic acids, viruses, bacteria and mammalian cells. A central challenge underlying the design of liquid crystalline materials for such applications is the tailoring of the interface of the materials so as to couple targeted biological interactions to ordering transitions. This review describes recent progress toward design of interfaces of liquid crystalline materials that are suitable for biological applications. Approaches addressed in this review include the use of lipid assemblies, polymeric membranes containing oligopeptides, cationic surfactant-DNA complexes, peptide-amphiphiles, interfacial protein assemblies and multi-layer polymeric films.

  14. Repetitive tabletop plasma focus to produce a tunable damage factor on materials for fusion reactors

    Science.gov (United States)

    Soto, Leopoldo; Pavez, Cristian; Inestrosa-Izurieta, Maria Jose; Moreno, Jose; Davis, Sergio; Bora, Biswajit; Avaria, Gonzalo; Jain, Jalaj; Altamirano, Luis; Panizo, Miguel; Gonzalez, Raquel; Rivera, Antonio

    2016-10-01

    Future thermonuclear reactors, both magnetic and inertial confinement approaches, need materials capable of withstanding the extreme radiation and heat loads expected from high repetition rate plasma. A damage factor (F = qτ1/2) in the order of 104 (W/cm2) s1/2 is expected. The axial plasma dynamics after the pinch in a tabletop plasma focus of hundred joules, PF-400J, was characterized by means of pulsed optical refractive diagnostics. The energy, interaction time and power flux of the plasma burst interacting with targets was obtained. Results show a high dependence of the damage factor with the distance from the anode top where the sample is located. A tunable damage factor in the range 10- 105(W/cm2) s1/2 can be obtained. At present the PF-400J operating at 0.077 Hz is being used to study the effects of fusion-relevant pulses on material target, including nanostructured materials. A new tabletop device to be operated up to 1Hz including tunable damage factor has been designed and is being constructed, thus thousand cumulative shots on materials could be obtained in few minutes. The scaling of the damage factor for plasma foci operating at different energies is discussed. Supported by CONICYT: PIA ACT-1115, PAI 79130026.

  15. Additive manufacturing of biologically-inspired materials.

    Science.gov (United States)

    Studart, André R

    2016-01-21

    Additive manufacturing (AM) technologies offer an attractive pathway towards the fabrication of functional materials featuring complex heterogeneous architectures inspired by biological systems. In this paper, recent research on the use of AM approaches to program the local chemical composition, structure and properties of biologically-inspired materials is reviewed. A variety of structural motifs found in biological composites have been successfully emulated in synthetic systems using inkjet-based, direct-writing, stereolithography and slip casting technologies. The replication in synthetic systems of design principles underlying such structural motifs has enabled the fabrication of lightweight cellular materials, strong and tough composites, soft robots and autonomously shaping structures with unprecedented properties and functionalities. Pushing the current limits of AM technologies in future research should bring us closer to the manufacturing capabilities of living organisms, opening the way for the digital fabrication of advanced materials with superior performance, lower environmental impact and new functionalities.

  16. Elucidation of Peptide-Directed Palladium Surface Structure for Biologically Tunable Nanocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bedford, Nicholas M.; Ramezani-Dakhel, Hadi; Slocik, Joseph M.; Briggs, Beverly D.; Ren, Yang; Frenkel, Anatoly I.; Petkov, Valeri; Heinz, Hendrik; Naik, Rajesh R.; Knecht, Mark R.

    2015-05-01

    Peptide-enabled synthesis of inorganic nanostructures represents an avenue to access catalytic materials with tunable and optimized properties. This is achieved via peptide complexity and programmability that is missing in traditional ligands for catalytic nanomaterials. Unfortunately, there is limited information available to correlate peptide sequence to particle structure and catalytic activity to date. As such, the application of peptide-enabled nanocatalysts remains limited to trial and error approaches. In this paper, a hybrid experimental and computational approach is introduced to systematically elucidate biomolecule-dependent structure/function relationships for peptide-capped Pd nanocatalysts. Synchrotron X-ray techniques were used to uncover substantial particle surface structural disorder, which was dependent upon the amino acid sequence of the peptide capping ligand. Nanocatalyst configurations were then determined directly from experimental data using reverse Monte Carlo methods and further refined using molecular dynamics simulation, obtaining thermodynamically stable peptide-Pd nanoparticle configurations. Sequence-dependent catalytic property differences for C-C coupling and olefin hydrogenation were then eluddated by identification of the catalytic active sites at the atomic level and quantitative prediction of relative reaction rates. This hybrid methodology provides a clear route to determine peptide-dependent structure/function relationships, enabling the generation of guidelines for catalyst design through rational tailoring of peptide sequences

  17. 37 CFR 1.801 - Biological material.

    Science.gov (United States)

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Biological material. 1.801 Section 1.801 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF.... Representative examples include bacteria, fungi including yeast, algae, protozoa, eukaryotic cells, cell...

  18. Recent developments in widely tunable and high peak power ultrafast laser sources and their adoption in biological imaging

    Science.gov (United States)

    Klein, J.

    2016-03-01

    Widely tunable ultrafast lasers have enabled a large number of biological imaging techniques including point scanning multiphoton excited fluorescence (MPEF), SHG/THG and stimulated Raman imaging. Tunable ultrafast lasers offer spectral agility, covering the entire relative transparency window in live tissue (700-1300nnm) and flexibility with multi-color, synchronized outputs to support sophisticated label free techniques (e.g. stimulated Raman modalities). More recently newly available high peak power lasers based on Ytterbium technology drive advances in two-photon light-sheet, 3 photon excited fluorescence and holographic patterning for optogenetics photo-stimulation. These laser platforms offer a unique blend of compactness, ease of use and cost efficiency, and ideally complement tunable platforms typically based on Ti:Sapphire and IR optical parametric oscillators (OPO). We present various types of ultrafast laser architectures, link their optical characteristics to key bio-imaging requirements, and present relevant examples and images illustrating their impact in biological science. In particular we review the use of ultrafast lasers in optogenetics for photo-stimulation of networks of neurons.

  19. Tunable mechanical characteristics of a novel soft magnetic entangled metallic wire material

    Science.gov (United States)

    Ma, Yanhong; Hu, Wenzhong; Zhang, Dayi; Zhang, Qicheng; Hong, Jie

    2016-09-01

    This article proposes a novel soft magnetic entangled metallic wire material(SM-EMWM) for the first time, and describes the manufacturing and quasi-static tests of its samples produced from soft magnetic metal wires. The mechanical properties of three batches of SM-EMWMs with different porosity have been investigated at different maximum strains in different external magnetic fields. The result shows that its properties (tangent modulus, loss factor) can be tunable in the magnetic field rapidly and reversibly. Compared with no magnetic field condition, the tangent modulus of SM-EMWM samples in a magnetic field of 500 mT can increase 2 ∼ 7 times on the average, while the loss factor averagely raises 10% ∼ 30%. The results show that the application of SM-EMWM, as a novel magneto-sensitive smart material, is feasible and applicable.

  20. Tunable ferrites as environmentally friendly materials for energy-efficient processes

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Serrano, Inmaculada; Arillo, Maria Angeles; Lopez, Maria Luisa; Veiga, Maria Luisa; Pico, Carlos [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid (Spain)

    2011-11-23

    Novel materials and methods of synthesis in the field of energy conversion and economy are reported. The main goal is to prepare and characterize Li{sub (4-x)}Mn{sub (5-2x)}Fe{sub 3x}O{sub 12} compounds. These compounds crystallize in a spinel-type structure, AB{sub 2}O{sub 4}, in which the cationic location in the A and B sublattices drives the potential application of these materials in two current prominent research fields: magnetic refrigeration and lithium batteries. This solid solution is revealed as a tunable system that nicely permits a specific response to be highlighted, depending on the composition and particle size: the magnetocaloric effect or active electrochemical behavior. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. An ultra-tunable platform for molecular engineering of high-performance crystalline porous materials

    Science.gov (United States)

    Zhai, Quan-Guo; Bu, Xianhui; Mao, Chengyu; Zhao, Xiang; Daemen, Luke; Cheng, Yongqiang; Ramirez-Cuesta, Anibal J.; Feng, Pingyun

    2016-12-01

    Metal-organic frameworks are a class of crystalline porous materials with potential applications in catalysis, gas separation and storage, and so on. Of great importance is the development of innovative synthetic strategies to optimize porosity, composition and functionality to target specific applications. Here we show a platform for the development of metal-organic materials and control of their gas sorption properties. This platform can accommodate a large variety of organic ligands and homo- or hetero-metallic clusters, which allows for extraordinary tunability in gas sorption properties. Even without any strong binding sites, most members of this platform exhibit high gas uptake capacity. The high capacity is accomplished with an isosteric heat of adsorption as low as 20 kJ mol-1 for carbon dioxide, which could bring a distinct economic advantage because of the significantly reduced energy consumption for activation and regeneration of adsorbents.

  2. Multiaxial mechanical behavior of biological materials.

    Science.gov (United States)

    Sacks, Michael S; Sun, Wei

    2003-01-01

    For native and engineered biological tissues, there exist many physiological, surgical, and medical device applications where multiaxial material characterization and modeling is required. Because biological tissues and many biocompatible elastomers are incompressible, planar biaxial testing allows for a two-dimensional (2-D) stress-state that can be used to fully characterize their three-dimensional (3-D) mechanical properties. Biological tissues exhibit complex mechanical behaviors not easily accounted for in classic elastomeric constitutive models. Accounting for these behaviors by careful experimental evaluation and formulation of constitutive models continues to be a challenging area in biomechanical modeling and simulation. The focus of this review is to describe the application of multiaxial testing techniques to soft tissues and their relation to modern biomechanical constitutive theories.

  3. Nanoarchitectured materials composed of fullerene-like spheroids and disordered graphene layers with tunable mechanical properties

    Science.gov (United States)

    Zhao, Zhisheng; Wang, Erik F.; Yan, Hongping; Kono, Yoshio; Wen, Bin; Bai, Ligang; Shi, Feng; Zhang, Junfeng; Kenney-Benson, Curtis; Park, Changyong; Wang, Yanbin; Shen, Guoyin

    2015-02-01

    Type-II glass-like carbon is a widely used material with a unique combination of properties including low density, high strength, extreme impermeability to gas and liquid and resistance to chemical corrosion. It can be considered as a carbon-based nanoarchitectured material, consisting of a disordered multilayer graphene matrix encasing numerous randomly distributed nanosized fullerene-like spheroids. Here we show that under both hydrostatic compression and triaxial deformation, this high-strength material is highly compressible and exhibits a superelastic ability to recover from large strains. Under hydrostatic compression, bulk, shear and Young’s moduli decrease anomalously with pressure, reaching minima around 1-2 GPa, where Poisson’s ratio approaches zero, and then revert to normal behaviour with positive pressure dependences. Controlling the concentration, size and shape of fullerene-like spheroids with tailored topological connectivity to graphene layers is expected to yield exceptional and tunable mechanical properties, similar to mechanical metamaterials, with potentially wide applications.

  4. Nanobiotechnology: synthetic biology meets materials science.

    Science.gov (United States)

    Jewett, Michael C; Patolsky, Fernando

    2013-08-01

    Nanotechnology, the area of science focused on the control of matter in the nanometer scale, allows ground-breaking changes of the fundamental properties of matter that are often radically different compared to those exhibited by the bulk counterparts. In view of the fact that dimensionality plays a key role in determining the qualities of matter, the realization of the great potential of nanotechnology has opened the door to other disciplines such as life sciences and medicine, where the merging between them offers exciting new applications, along with basic science research. The application of nanotechnology in life sciences, nanobiotechnology, is now having a profound impact on biological circuit design, bioproduction systems, synthetic biology, medical diagnostics, disease therapy and drug delivery. This special issue is dedicated to the overview of how we are learning to control biopolymers and biological machines at the molecular- and nanoscale. In addition, it covers far-reaching progress in the design and synthesis of nanoscale materials, thus enabling the construction of integrated systems in which the component blocks are comparable in size to the chemical and biological entities under investigation.

  5. Tunable PhoXonic Band Gap Materials from Self-Assembly of Block Copoliymers and Colloidal Nanocrystals (NBIT Phase II)

    Science.gov (United States)

    2011-05-06

    Final Report for AOARD Grant 1014069 “Tunable PhoXonic Band Gap Materials from Self-Assembly of Block Copoliymers and Colloidal Nanocrystals...NBIT Phase II)” 5 July 2011 Name of Principal Investigators: Edwin L Thomas, Dept of Materials Science and Engineering, MIT e-mail address... elt @mit.edu Institution : Massachusetts Institute of Technology Mailing Address : 77 Mass. Avenue, 6-113, Cambridge, MA 02139 Phone : 617-253-6901

  6. Acousto-Optic Tunable Filter Spectroscopic Instrumentation for Quantitative Near-Ir Analysis of Organic Materials.

    Science.gov (United States)

    Eilert, Arnold James

    1995-01-01

    The utility of near-IR spectroscopy for routine quantitative analyses of a wide variety of compositional, chemical, or physical parameters of organic materials is well understood. It can be used for relatively fast and inexpensive non-destructive bulk material analysis before, during, and after processing. It has been demonstrated as being a particularly useful technique for numerous analytical applications in cereal (food and feed) science and industry. Further fulfillment of the potential of near-IR spectroscopic analysis, both in the process and laboratory environment, is reliant upon the development of instrumentation that is capable of meeting the challenges of increasingly difficult applications. One approach to the development of near-IR spectroscopic instrumentation that holds a great deal of promise is acousto-optic tunable filter (AOTF) technology. A combination of attributes offered by AOTF spectrometry, including speed, optical throughput, wavelength reproducibility, ruggedness (no -moving-parts operation) and flexibility, make it particularly desirable for numerous applications. A series of prototype (research model) acousto -optic tunable filter instruments were developed and tested in order to investigate the feasibility of the technology for quantitative near-IR spectrometry. Development included design, component procurement, assembly and/or configuration of the optical and electronic subsystems of which each functional spectrometer arrangement was comprised, as well as computer interfacing and acquisition/control software development. Investigation of this technology involved an evolution of several operational spectrometer systems, each of which offered improvements over its predecessor. Appropriate testing was conducted at various stages of development. Demonstrations of the potential applicability of our AOTF spectrometer to quantitative process monitoring or laboratory analysis of numerous organic substances, including food materials, were

  7. Accidents with biological material in workers

    Directory of Open Access Journals (Sweden)

    Cleonice Andréa Alves Cavalcante

    2013-11-01

    Full Text Available The objective was to describe the accidents with biological material occurred among workers of Rio Grande do Norte, Brazil, between 2007 and 2009. Secondary data were collected in the National Notifiable Diseases Surveillance System by exporting data to Excel using Tabwin. Among the types of occupational accidents reported in the state, the biological accidents (no. = 1,170 accounted for 58.3% with a predominance of cases among nurses (48.6%. The percutaneous exposure was the most frequent occurrence and the circumstances of the accidents were related to the handling of sharps and the most common organic material was blood (63.5%. More than 50% of the workers were vaccinated against hepatitis B, but without information regarding the evaluation of vaccine response. The study revealed the need of improvement in the quality of the information, once the sub-entries and inconsistencies make the National Notifiable Diseases Surveillance System less trustworthy in the characterization of the affected workers.

  8. Biologically relevant photoacoustic imaging phantoms with tunable optical and acoustic properties

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Joshua Pfefer, T.

    2016-10-01

    Established medical imaging technologies such as magnetic resonance imaging and computed tomography rely on well-validated tissue-simulating phantoms for standardized testing of device image quality. The availability of high-quality phantoms for optical-acoustic diagnostics such as photoacoustic tomography (PAT) will facilitate standardization and clinical translation of these emerging approaches. Materials used in prior PAT phantoms do not provide a suitable combination of long-term stability and realistic acoustic and optical properties. Therefore, we have investigated the use of custom polyvinyl chloride plastisol (PVCP) formulations for imaging phantoms and identified a dual-plasticizer approach that provides biologically relevant ranges of relevant properties. Speed of sound and acoustic attenuation were determined over a frequency range of 4 to 9 MHz and optical absorption and scattering over a wavelength range of 400 to 1100 nm. We present characterization of several PVCP formulations, including one designed to mimic breast tissue. This material is used to construct a phantom comprised of an array of cylindrical, hemoglobin-filled inclusions for evaluation of penetration depth. Measurements with a custom near-infrared PAT imager provide quantitative and qualitative comparisons of phantom and tissue images. Results indicate that our PVCP material is uniquely suitable for PAT system image quality evaluation and may provide a practical tool for device validation and intercomparison.

  9. Solid freeform fabrication of biological materials

    Science.gov (United States)

    Wang, Jiwen

    This thesis investigates solid freeform fabrication of biological materials for dental restoration and orthopedic implant applications. The basic approach in this study for solid freeform fabrication of biological materials is micro-extrusion of single or multiple slurries for 3D components and inkjet color printing of multiple suspensions for functionally graded materials (FGMs). Common issues associated with micro-extrusion and inkjet color printing are investigated. These common issues include (i) formulation of stable slurries with a pseudoplastic property, (ii) cross-sectional geometry of the extrudate as a function of the extrusion parameters, (iii) fabrication path optimization for extrusion process, (iv) extrusion optimization for multi-layer components, (v) composition control in functionally graded materials, and (vi) sintering optimization to convert the freeform fabricated powder compact to a dense body for biological applications. The present study clearly shows that the rheological and extrusion behavior of dental porcelain slurries depend strongly on the pH value of the slurry and extrusion conditions. A slurry with pseudoplastic properties is a basic requirement for obtaining extruded lines with rectangular cross-sections. The cross-sectional geometry of the extrudate is also strongly affected by extrusion parameters including the extrusion nozzle height, nozzle moving speed, extrusion rate, and critical nozzle height. Proper combinations of these extrusion parameters are necessary in order to obtain single line extrudates with near rectangular cross-sections and 3D objects with dimensional accuracy, uniform wall thickness, good wall uprightness, and no wall slumping. Based on these understandings, single-wall, multi-wall, and solid teeth have been fabricated via micro-extrusion of the dental slurry directly from a CAD digital model in 30 min. Inkjet color printing using stable Al2O3 and ZrO 2 aqueous suspensions has been developed to fabricate

  10. Utilizing stretch-tunable thermochromic elastomeric opal films as novel reversible switchable photonic materials.

    Science.gov (United States)

    Schäfer, Christian G; Lederle, Christina; Zentel, Kristina; Stühn, Bernd; Gallei, Markus

    2014-11-01

    In this work, the preparation of highly thermoresponsive and fully reversible stretch-tunable elastomeric opal films featuring switchable structural colors is reported. Novel particle architectures based on poly(diethylene glycol methylether methacrylate-co-ethyl acrylate) (PDEGMEMA-co-PEA) as shell polymer are synthesized via seeded and stepwise emulsion polymerization protocols. The use of DEGMEMA as comonomer and herein established synthetic strategies leads to monodisperse soft shell particles, which can be directly processed to opal films by using the feasible melt-shear organization technique. Subsequent UV crosslinking strategies open access to mechanically stable and homogeneous elastomeric opal films. The structural colors of the opal films feature mechano- and thermoresponsiveness, which is found to be fully reversible. Optical characterization shows that the combination of both stimuli provokes a photonic bandgap shift of more than 50 nm from 560 nm in the stretched state to 611 nm in the fully swollen state. In addition, versatile colorful patterns onto the colloidal crystal structure are produced by spatial UV-induced crosslinking by using a photomask. This facile approach enables the generation of spatially cross-linked switchable opal films with fascinating optical properties. Herein described strategies for the preparation of PDEGMEMA-containing colloidal architectures, application of the melt-shear ordering technique, and patterned crosslinking of the final opal films open access to novel stimuli-responsive colloidal crystal films, which are expected to be promising materials in the field of security and sensing applications.

  11. Tunable M-channel filter based on Thue-Morse heterostructures containing meta materials

    Directory of Open Access Journals (Sweden)

    H Pashaei Adl

    2015-01-01

    Full Text Available In this paper the tunable M-channel filters based on Thue-Morse heterostructures consisting of single -negative materials has been studied. The results showed that the number of resonance modes inside the zero- gap increases as the number of heterogenous interface, M, increases. The number of resonance modes inside the zero- gap is equal to that of heterogenous interface M, and it can be used as M channels filter. This result provides a feasible method to adjust the channel number of multiple-channel filters. When losses are involved, the results showed that the electric fields of the resonance modes decay largely with the increase of the number of heterogenous interface and damping factors. Besides, the relationship between the quality factor of multiple-channel filters and the number of heterogenous interface M is linear, and the quality factor of multiple-channel filters decreases with the increase of the damping factor. These results provide feasible methods to adjust the quality factor of multiple-channel filters

  12. Fabrication of nanoscale to macroscale nickel-multiwall carbon nanotube hybrid materials with tunable material properties

    Science.gov (United States)

    Abdalla, Ahmed M.; Majdi, Tahereh; Ghosh, Suvojit; Puri, Ishwar K.

    2016-12-01

    To utilize their superior properties, multiwall carbon nanotubes (MWNTs) must be manipulated and aligned end-to-end. We describe a nondestructive method to magnetize MWNTs and provide a means to remotely manipulate them through the electroless deposition of magnetic nickel nanoparticles on their surfaces. The noncovalent bonds between Ni nanoparticles and MWNTs produce a Ni-MWNT hybrid material (NiCH) that is electrically conductive and has an enhanced magnetic susceptibility and elastic modulus. Our experiments show that MWNTs can be plated with Ni for Ni:MWNT weight ratios of γ = 1, 7, 14 and 30, to control the material properties. The phase, atom-level, and morphological information from x-ray diffraction, energy dispersive x-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, dark field STEM, and atomic force microscopy clarify the plating process and reveal the mechanical properties of the synthesized material. Ni metalizes at the surface of the Pd catalyst, forming a continuous wavy layer that encapsulates the MWNT surfaces. Subsequently, Ni acts as an autocatalyst, allowing the plating to continue even after the original Pd catalyst has been completely covered. Raising γ increases the coating layer thickness from 10 to 150 nm, which influences the NiCH magnetic properties and tunes its elastic modulus from 12.5 to 58.7 GPa. The NiCH was used to fabricate Ni-MWNT macrostructures and tune their morphologies by changing the direction of an applied magnetic field. Leveraging the hydrophilic Ni-MWNT outer surface, a water-based conductive ink was created and used to print a conductive path that had an electrical resistivity of 5.9 Ω m, illustrating the potential of this material for printing electronic circuits.

  13. Programmable temperature control system for biological materials

    Science.gov (United States)

    Anselmo, V. J.; Harrison, R. G.; Rinfret, A. P.

    1982-01-01

    A system was constructed which allows programmable temperature-time control for a 5 cu cm sample volume of arbitrary biological material. The system also measures the parameters necessary for the determination of the sample volume specific heat and thermal conductivity as a function of temperature, and provides a detailed measurement of the temperature during phase change and a means of calculating the heat of the phase change. Steady-state and dynamic temperature control is obtained by supplying heat to the sample volume through resistive elements constructed as an integral part of the sample container. For cooling purposes, this container is totally immersed into a cold heat sink. Using a mixture of dry ice and alcohol at 79 C, the sample volume can be controlled from +40 to -60 C at rates from steady state to + or - 65 C/min. Steady-state temperature precision is better than 0.2 C, while the dynamic capability depends on the temperature rate of change as well as the mass of both the sample and the container.

  14. Tunable plasmonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  15. Gate-tunable diode and photovoltaic effect in an organic-2D layered material p-n junction.

    Science.gov (United States)

    Vélez, Saül; Ciudad, David; Island, Joshua; Buscema, Michele; Txoperena, Oihana; Parui, Subir; Steele, Gary A; Casanova, Fèlix; van der Zant, Herre S J; Castellanos-Gomez, Andres; Hueso, Luis E

    2015-10-01

    The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 10(4), while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ∼11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.

  16. Laser interaction with biological material mathematical modeling

    CERN Document Server

    Kulikov, Kirill

    2014-01-01

    This book covers the principles of laser interaction with biological cells and tissues of varying degrees of organization. The problems of biomedical diagnostics are considered. Scattering of laser irradiation of blood cells is modeled for biological structures (dermis, epidermis, vascular plexus). An analytic theory is provided which is based on solving the wave equation for the electromagnetic field. It allows the accurate analysis of interference effects arising from the partial superposition of scattered waves. Treated topics of mathematical modeling are: optical characterization of biological tissue with large-scale and small-scale inhomogeneities in the layers, heating blood vessel under laser irradiation incident on the outer surface of the skin and thermo-chemical denaturation of biological structures at the example of human skin.

  17. Biological inspiration in optics and photonics: harnessing nature's light manipulation strategies for multifunctional optical materials (Conference Presentation)

    Science.gov (United States)

    Kolle, Mathias; Sandt, Joseph D.; Nagelberg, Sara N.; Zarzar, Lauren D.; Kreysing, Moritz; Vukusic, Peter

    2016-03-01

    The precise control of light-matter interactions is crucial for the majority of known biological organisms in their struggle to survive. Many species have evolved unique methods to manipulate light in their environment using a variety of physical effects including pigment-induced, spectrally selective absorption or light interference in photonic structures that consist of micro- and nano-periodic material morphologies. In their optical performance, many of the known biological photonic systems are subject to selection criteria not unlike the requirements faced in the development of novel optical technology. For this reason, biological light manipulation strategies provide inspiration for the creation of tunable, stimuli-responsive, adaptive material platforms that will contribute to the development of multifunctional surfaces and innovative optical technology. Biomimetic and bio-inspired approaches for the manufacture of photonic systems rely on self-assembly and bottom-up growth techniques often combined with conventional top-down manufacturing. In this regard, we can benefit in several ways from highly sophisticated material solutions that have convergently evolved in various organisms. We explore design concepts found in biological photonic architectures, seek to understand the mechanisms underlying morphogenesis of bio-optical systems, aim to devise viable manufacturing strategies that can benefit from insight in biological formation processes and the use of established synthetic routines alike, and ultimately strive to realize new photonic materials with tailor-made optical properties. This talk is focused on the identification of biological role model photonic architectures, a brief discussion of recently developed bio-inspired photonic structures, including mechano-sensitive color-tunable photonic fibers and reconfigurable fluid micro-lenses. Potentially, early-stage results in studying and harnessing the structure-forming capabilities of living cells that

  18. The acquisition of dangerous biological materials :

    Energy Technology Data Exchange (ETDEWEB)

    Aceto, Donato Gonzalo; Astuto-Gribble, Lisa M.; Gaudioso, Jennifer M.

    2007-11-01

    Numerous terrorist organizations have openly expressed interest in producing and deploying biological weapons. However, a limiting factor for many terrorists has been the acquisition of dangerous biological agents, as evidenced by the very few successful instances of biological weapons use compared to the number of documented hoaxes. Biological agents vary greatly in their ability to cause loss of life and economic damage. Some agents, if released properly, can kill many people and cause an extensive number of secondary infections; other agents will sicken only a small number of people for a short period of time. Consequently, several biological agents can potentially be used to perpetrate a bioterrorism attack but few are likely capable of causing a high consequence event. It is crucial, from a US national security perspective, to more deeply understand the likelihood that terrorist organizations can acquire the range of these agents. Few studies have attempted to comprehensively compile the technical information directly relevant to the acquisition of dangerous bacteria, viruses and toxins. In this report, technical fact sheets were assembled for 46 potentially dangerous biological agents. Much of the information was taken from various research sources which could ultimately and significantly expedite and improve bioterrorism threat assessments. By systematically examining a number of specific agent characteristics included in these fact sheets, it may be possible to detect, target, and implement measures to thwart future terrorist acquisition attempts. In addition, the information in these fact sheets may be used as a tool to help laboratories gain a rudimentary understanding of how attractive a method laboratory theft is relative to other potential acquisition modes.

  19. Materiomics: biological protein materials, from nano to macro.

    Science.gov (United States)

    Cranford, Steven; Buehler, Markus J

    2010-11-12

    Materiomics is an emerging field of science that provides a basis for multiscale material system characterization, inspired in part by natural, for example, protein-based materials. Here we outline the scope and explain the motivation of the field of materiomics, as well as demonstrate the benefits of a materiomic approach in the understanding of biological and natural materials as well as in the design of de novo materials. We discuss recent studies that exemplify the impact of materiomics - discovering Nature's complexity through a materials science approach that merges concepts of material and structure throughout all scales and incorporates feedback loops that facilitate sensing and resulting structural changes at multiple scales. The development and application of materiomics is illustrated for the specific case of protein-based materials, which constitute the building blocks of a variety of biological systems such as tendon, bone, skin, spider silk, cells, and tissue, as well as natural composite material systems (a combination of protein-based and inorganic constituents) such as nacre and mollusk shells, and other natural multiscale systems such as cellulose-based plant and wood materials. An important trait of these materials is that they display distinctive hierarchical structures across multiple scales, where molecular details are exhibited in macroscale mechanical responses. Protein materials are intriguing examples of materials that balance multiple tasks, representing some of the most sustainable material solutions that integrate structure and function despite severe limitations in the quality and quantity of material building blocks. However, up until now, our attempts to analyze and replicate Nature's materials have been hindered by our lack of fundamental understanding of these materials' intricate hierarchical structures, scale-bridging mechanisms, and complex material components that bestow protein-based materials their unique properties. Recent

  20. Tunable geometry of bacterial inclusion bodies as substrate materials for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    GarcIa-Fruitos, Elena; Seras-Franzoso, JoaquIn; Vazquez, Esther; Villaverde, Antonio [CIBER en BioingenierIa, Biomateriales y Nanomedicina, Bellaterra, 08193 Barcelona (Spain); Institut de Biotecnologia i de Biomedicina and Departament de Genetica i de Microbiologia, Universitat Autonoma de Barcelona, 08193 Bellaterra (Cerdanyola del Valles), Barcelona (Spain)

    2010-05-21

    A spectrum of materials for biomedical applications is produced in bacteria, and some of them, such as metals or polyhydroxyalkanoates, are straightforwardly obtained as particulate entities. We have explored the biofabrication process of bacterial inclusion bodies, particulate proteinaceous materials (ranging from 50 to 500 nm in diameter) recently recognized as suitable for surface topographical modification and tissue engineering. Inclusion bodies have been widely described as spherical or pseudo-spherical particles with only minor morphological variability, mostly restricted to their size. Here we have identified a cellular gene in Escherichia coli (clpP) that controls the in vivo fabrication process of inclusion bodies. In the absence of the encoded protease, the dynamics of protein deposition is perturbed, resulting in unusual tear-shaped particles with enhanced surface-volume ratios. This fact modifies the ability of inclusion bodies to promote mammalian cell attachment and differentiation upon surface decoration. The implications of the genetic control of inclusion body geometry are discussed in the context of their biological fabrication and regarding the biomedical potential of these protein clusters in regenerative medicine.

  1. Mathematical and numerical challenges in living biological materials

    Science.gov (United States)

    Forest, M. Gregory; Vasquez, Paula A.

    2013-10-01

    The proclaimed Century of Biology is rapidly leading to the realization of how starkly different and more complex biological materials are than the materials that underpinned the industrial and technological revolution. These differences arise, in part, because biological matter exhibits both viscous and elastic behavior. Moreover, this behavior varies across the frequency, wavelength and amplitude spectrum of forcing. This broadclass of responsesin biological matter requires multiple frequency-dependent functions to specify material behavior, instead of a discrete set of parameters that relate to either viscosity or elasticity. This complexity prevails even if the biological matter is assumed to be spatially homogeneous, which is rarely true. However, very little progress has been made on the characterization of heterogeneity and how to build that information into constitutive laws and predictive models. In addition, most biological matter is non-stationary, which motivates the term "living". Biomaterials typically are in an active state in order to perform certain functions, and they often are modified or replenished on the basis of external stimuli. It has become popular in materials engineering to try to duplicate some of the functionality of biomaterials, e.g., a lot of effort has gone into the design of self-assembling, self-healing and shape shifting materials. These distinguishing features of biomaterials require significantly more degrees of freedom than traditional composites and many of the molecular species and their roles in functionality have yet to be determined. A typical biological material includes small molecule biochemical species that react and diffuse within larger species. These large molecular weightspecies provide the primary structural and biophysical properties of the material. The small molecule binding and unbinding kinetics serves to modulate material properties, and typical small molecule production and release are governed by

  2. Biological issues in materials science and engineering: Interdisciplinarity and the bio-materials paradigm

    Science.gov (United States)

    Murr, L. E.

    2006-07-01

    Biological systems and processes have had, and continue to have, important implications and applications in materials extraction, processing, and performance. This paper illustrates some interdisciplinary, biological issues in materials science and engineering. These include metal extraction involving bacterial catalysis, galvanic couples, bacterial-assisted corrosion and degradation of materials, biosorption and bioremediation of toxic and other heavy metals, metal and material implants and prostheses and related dental and medical biomaterials developments and applications, nanomaterials health benefits and toxicity issue, and biomimetics and biologically inspired materials developments. These and other examples provide compelling evidence and arguments for emphasizing biological sicences in materials science and engineering curricula and the implementation of a bio-materials paradigm to facilitate the emergence of innovative interdisciplinarity involving the biological sciences and materials sciences and engineering.

  3. Material science lesson from the biological photosystem

    Science.gov (United States)

    Kim, Younghye; Lee, Jun Ho; Ha, Heonjin; Im, Sang Won; Nam, Ki Tae

    2016-08-01

    Inspired by photosynthesis, artificial systems for a sustainable energy supply are being designed. Each sequential energy conversion process from light to biomass in natural photosynthesis is a valuable model for an energy collection, transport and conversion system. Notwithstanding the numerous lessons of nature that provide inspiration for new developments, the features of natural photosynthesis need to be reengineered to meet man's demands. This review describes recent strategies toward adapting key lessons from natural photosynthesis to artificial systems. We focus on the underlying material science in photosynthesis that combines photosystems as pivotal functional materials and a range of materials into an integrated system. Finally, a perspective on the future development of photosynthesis mimetic energy systems is proposed.

  4. Analytical Chemistry at the Interface Between Materials Science and Biology

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Janese C. [Iowa State Univ., Ames, IA (United States)

    2000-09-21

    Likedlessentid sciences, anal~cd chetis~continues toreinvent itself. Moving beyond its traditional roles of identification and quantification, analytical chemistry is now expanding its frontiers into areas previously reserved to other disciplines. This work describes several research efforts that lie at the new interfaces between analytical chemistry and two of these disciplines, namely materials science and biology. In the materials science realm, the search for new materials that may have useful or unique chromatographic properties motivated the synthesis and characterization of electrically conductive sol-gels. In the biology realm, the search for new surface fabrication schemes that would permit or even improve the detection of specific biological reactions motivated the design of miniaturized biological arrays. Collectively, this work represents some of analytical chemistry’s newest forays into these disciplines. The introduction section to this dissertation provides a literature review on several of the key aspects of this work. In advance of the materials science discussion, a brief introduction into electrochemically-modulated liquid chromatography (EMLC) and sol-gel chemistry is provided. In advance of the biological discussions, brief overviews of scanning force microscopy (SFM) and the oxidative chemistry used to construct our biological arrays are provided. This section is followed by four chapters, each of which is presented as a separate manuscript, and focuses on work that describes some of our cross-disciplinary efforts within materials science and biology. This dissertation concludes with a general summary and future prospectus.

  5. Tunable nanowire nonlinear optical probe

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Yuri; Pauzauskie, Peter J.; Radenovic, Aleksandra; Onorato, Robert M.; Saykally, Richard J.; Liphardt, Jan; Yang, Peidong

    2008-02-18

    One crucial challenge for subwavelength optics has been thedevelopment of a tunable source of coherent laser radiation for use inthe physical, information, and biological sciences that is stable at roomtemperature and physiological conditions. Current advanced near-fieldimaging techniques using fiber-optic scattering probes1,2 have alreadyachieved spatial resolution down to the 20-nm range. Recently reportedfar-field approaches for optical microscopy, including stimulatedemission depletion (STED)3, structured illumination4, and photoactivatedlocalization microscopy (PALM)5, have also enabled impressive,theoretically-unlimited spatial resolution of fluorescent biomolecularcomplexes. Previous work with laser tweezers6-8 has suggested the promiseof using optical traps to create novel spatial probes and sensors.Inorganic nanowires have diameters substantially below the wavelength ofvisible light and have unique electronic and optical properties9,10 thatmake them prime candidates for subwavelength laser and imagingtechnology. Here we report the development of an electrode-free,continuously-tunable coherent visible light source compatible withphysiological environments, from individual potassium niobate (KNbO3)nanowires. These wires exhibit efficient second harmonic generation(SHG), and act as frequency converters, allowing the local synthesis of awide range of colors via sum and difference frequency generation (SFG,DFG). We use this tunable nanometric light source to implement a novelform of subwavelength microscopy, in which an infrared (IR) laser is usedto optically trap and scan a nanowire over a sample, suggesting a widerange of potential applications in physics, chemistry, materials science,and biology.

  6. Improved tunable filter-based multispectral imaging system for detection of blood stains on construction material substrates

    Science.gov (United States)

    Janchaysang, Suwatwong; Sumriddetchkajorn, Sarun; Buranasiri, Prathan

    2013-06-01

    We present the improved tunable filter based multispectral imaging system for detecting blood stains on construction materials. Based upon the reflectance and Kubelka Munk absorbance spectra stocked from our previous work, we modify the blood discrimination criteria to make the system more efficient by replacing the old criteria which make use of polynomial fitting with new criteria associated with a few wavelengths images. The newly established criteria are tested to be able to detect blood against other stains almost as efficient as the old criteria, while the number of spectral images required for detecting blood stains are reduced significantly from 64 to 9 spectral images. The reduction of required spectral images will reduce the time needed for image capturing and blood detection criteria application with little sacrificing of the specificity and sensitivity of the system.

  7. Editorial:Mechanics of biological and bio-inspired materials%Editorial: Mechanics of biological and bio-inspired materials

    Institute of Scientific and Technical Information of China (English)

    Baohua Jia

    2012-01-01

    The field of mechanics of biological and bio-inspired materials underwent an exciting development over the past several years,which made it stand at the cutting edge of both engineering mechanics and biomechanics.As an intriguing interdisciplinary research field,it aims at elucidating the fundamental principles in nature's design of strong,multi-functional and smart Materials by focusing on the assembly,deformation,stability and failure of the materials.These principles should have wide applications in not only material sciences and mechanical engineering but also biomedical engineering.For instance,the knowledge in Mechanical principles of biological materials is very helpful for addressing some major challenges in material sciences and engineering.They also have the potential to provide quantitative understanding about how forces and deformation affect human being's health,diseases and treatment at tissue,cellular and molecular levels.This special subject on "mechanics of biological and bio-inspired materials" collects a few studies on recent development by leading scientists in this field.The biological materials or systems in these studies include cell,cytoskeleton (e.g.,microtubulus,intermediate filaments),lipid molecules and composite system of lipid and nanoparticle,tissue,and biological attachment systems,etc.

  8. Materiomics: biological protein materials, from nano to macro

    Directory of Open Access Journals (Sweden)

    Steven Cranford

    2010-11-01

    Full Text Available Steven Cranford, Markus J BuehlerCenter for Materials Science and Engineering, Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USAAbstract: Materiomics is an emerging field of science that provides a basis for multiscale material system characterization, inspired in part by natural, for example, protein-based materials. Here we outline the scope and explain the motivation of the field of materiomics, as well as demonstrate the benefits of a materiomic approach in the understanding of biological and natural materials as well as in the design of de novo materials. We discuss recent studies that exemplify the impact of materiomics – discovering Nature’s complexity through a materials science approach that merges concepts of material and structure throughout all scales and incorporates feedback loops that facilitate sensing and resulting structural changes at multiple scales. The development and application of materiomics is illustrated for the specific case of protein-based materials, which constitute the building blocks of a variety of biological systems such as tendon, bone, skin, spider silk, cells, and tissue, as well as natural composite material systems (a combination of protein-based and inorganic constituents such as nacre and mollusk shells, and other natural multiscale systems such as cellulose-based plant and wood materials. An important trait of these materials is that they display distinctive hierarchical structures across multiple scales, where molecular details are exhibited in macroscale mechanical responses. Protein materials are intriguing examples of materials that balance multiple tasks, representing some of the most sustainable material solutions that integrate structure and function despite severe limitations in the quality and quantity of material building blocks. However, up until now, our attempts to analyze and

  9. Analysis and Design of Biological Materials and Structures

    CERN Document Server

    Öchsner, Andreas; Altenbach, Holm

    2012-01-01

    This collection provides researchers and scientists with advanced analyses and materials design techniques in Biomaterials and presents mechanical studies of biological structures. In 16 contributions well known experts present their research on Stress and Strain Analysis, Material Properties, Fluid and Gas mechanics and they show related problems.

  10. Materials and methods for delivery of biological drugs

    Science.gov (United States)

    Zelikin, Alexander N.; Ehrhardt, Carsten; Healy, Anne Marie

    2016-11-01

    Biological drugs generated via recombinant techniques are uniquely positioned due to their high potency and high selectivity of action. The major drawback of this class of therapeutics, however, is their poor stability upon oral administration and during subsequent circulation. As a result, biological drugs have very low bioavailability and short therapeutic half-lives. Fortunately, tools of chemistry and biotechnology have been developed into an elaborate arsenal, which can be applied to improve the pharmacokinetics of biological drugs. Depot-type release systems are available to achieve sustained release of drugs over time. Conjugation to synthetic or biological polymers affords long circulating formulations. Administration of biological drugs through non-parenteral routes shows excellent performance and the first products have reached the market. This Review presents the main accomplishments in this field and illustrates the materials and methods behind existing and upcoming successful formulations and delivery strategies for biological drugs.

  11. Tunable micro-optics

    CERN Document Server

    Duppé, Claudia

    2015-01-01

    Presenting state-of-the-art research into the dynamic field of tunable micro-optics, this is the first book to provide a comprehensive survey covering a varied range of topics including novel materials, actuation concepts and new imaging systems in optics. Internationally renowned researchers present a diverse range of chapters on cutting-edge materials, devices and subsystems, including soft matter, artificial muscles, tunable lenses and apertures, photonic crystals, and complete tunable imagers. Special contributions also provide in-depth treatment of micro-optical characterisation, scanners, and the use of natural eye models as inspiration for new concepts in advanced optics. With applications extending from medical diagnosis to fibre telecommunications, Tunable Micro-optics equips readers with a solid understanding of the broader technical context through its interdisciplinary approach to the realisation of new types of optical systems. This is an essential resource for engineers in industry and academia,...

  12. Occupational accidents involving biological material among public health workers.

    Science.gov (United States)

    Chiodi, Mônica Bonagamba; Marziale, Maria Helena Palucci; Robazzi, Maria Lúcia do Carmo Cruz

    2007-01-01

    This descriptive research aimed to recognize the occurrence of work accidents (WA) involving exposure to biological material among health workers at Public Health Units in Ribeirão Preto-SP, Brazil. A quantitative approach was adopted. In 2004, 155 accidents were notified by means of the Work Accident Communication (WAC). Sixty-two accidents (40%) involved exposure to biological material that could cause infections like Hepatitis and Aids. The highest number of victims (42 accidents) came from the category of nursing aids and technicians. Needles were responsible for 80.6% of accidents and blood was the biological material involved in a majority of occupational exposure cases. This subject needs greater attention, so that prevention measures can be implemented, which consider the peculiarities of the activities carried out by the different professional categories.

  13. Materials Manufactured from 3D Printed Synthetic Biology Arrays

    Science.gov (United States)

    Gentry, Diana; Micks, Ashley

    2013-01-01

    Many complex, biologically-derived materials have extremely useful properties (think wood or silk), but are unsuitable for space-related applications due to production, manufacturing, or processing limitations. Large-scale ecosystem-based production, such as raising and harvesting trees for wood, is impractical in a self-contained habitat such as a space station or potential Mars colony. Manufacturing requirements, such as the specialized equipment needed to harvest and process cotton, add too much upmass for current launch technology. Cells in nature are already highly specialized for making complex biological materials on a micro scale. We envision combining these strengths with the recently emergent technologies of synthetic biology and 3D printing to create 3D-structured arrays of cells that are bioengineered to secrete different materials in a specified three-dimensional pattern.

  14. Flexible Organic Electronics in Biology: Materials and Devices.

    Science.gov (United States)

    Liao, Caizhi; Zhang, Meng; Yao, Mei Yu; Hua, Tao; Li, Li; Yan, Feng

    2015-12-09

    At the convergence of organic electronics and biology, organic bioelectronics attracts great scientific interest. The potential applications of organic semiconductors to reversibly transmit biological signals or stimulate biological tissues inspires many research groups to explore the use of organic electronics in biological systems. Considering the surfaces of movable living tissues being arbitrarily curved at physiological environments, the flexibility of organic bioelectronic devices is of paramount importance in enabling stable and reliable performances by improving the contact and interaction of the devices with biological systems. Significant advances in flexible organic bio-electronics have been achieved in the areas of flexible organic thin film transistors (OTFTs), polymer electrodes, smart textiles, organic electrochemical ion pumps (OEIPs), ion bipolar junction transistors (IBJTs) and chemiresistors. This review will firstly discuss the materials used in flexible organic bioelectronics, which is followed by an overview on various types of flexible organic bioelectronic devices. The versatility of flexible organic bioelectronics promises a bright future for this emerging area.

  15. Near-Infrared Fluorescent Materials for Sensing of Biological Targets

    Directory of Open Access Journals (Sweden)

    Julia Xiaojun Zhao

    2008-05-01

    Full Text Available Near-infrared fluorescent (NIRF materials are promising labeling reagents for sensitive determination and imaging of biological targets. In the near-infrared region biological samples have low background fluorescence signals, providing high signal to noise ratio. Meanwhile, near-infrared radiation can penetrate into sample matrices deeply due to low light scattering. Thus, in vivo and in vitro imaging of biological samples can be achieved by employing the NIRF probes. To take full advantage of NIRF materials in the biological and biomedical field, one of the key issues is to develop intense and biocompatible NIRF probes. In this review, a number of NIRF materials are discussed including traditional NIRF dye molecules, newly developed NIRF quantum dots and single-walled carbon nanotubes, as well as rare earth metal compounds. The use of some NIRF materials in various nanostructures is illustrated. The enhancement of NIRF using metal nanostructures is covered as well. The fluorescence mechanism and bioapplications of each type of the NIRF materials are discussed in details.

  16. Porous Materials with Tunable Structure and Mechanical Properties via Templated Layer-by-Layer Assembly.

    Science.gov (United States)

    Ziminska, Monika; Dunne, Nicholas; Hamilton, Andrew R

    2016-08-31

    The deposition of stiff and strong coatings onto porous templates offers a novel strategy for fabricating macroscale materials with controlled architectures at the micro- and nanoscale. Here, layer-by-layer assembly is utilized to fabricate nanocomposite-coated foams with highly customizable properties by depositing polymer-nanoclay coatings onto open-cell foam templates. The compressive mechanical behavior of these materials evolves in a predictable manner that is qualitatively captured by scaling laws for the mechanical properties of cellular materials. The observed and predicted properties span a remarkable range of density-stiffness space, extending from regions of very soft elastomer foams to very stiff, lightweight honeycomb and lattice materials.

  17. Electron Microscopy of Biological Materials at the Nanometer Scale

    Science.gov (United States)

    Kourkoutis, Lena Fitting; Plitzko, Jürgen M.; Baumeister, Wolfgang

    2012-08-01

    Electron microscopy of biological matter uses three different imaging modalities: (a) electron crystallography, (b) single-particle analysis, and (c) electron tomography. Ideally, these imaging modalities are applied to frozen-hydrated samples to ensure an optimal preservation of the structures under scrutiny. Cryo-electron microscopy of biological matter has made important advances in the past decades. It has become a research tool that further expands the scope of structural research into unique areas of cell and molecular biology, and it could augment the materials research portfolio in the study of soft and hybrid materials. This review addresses how researchers using transmission electron microscopy can derive structural information at high spatial resolution from fully hydrated specimens, despite their sensitivity to ionizing radiation, despite the adverse conditions of high vacuum for samples that have to be kept in aqueous environments, and despite their low contrast resulting from weakly scattering building blocks.

  18. Theory of light transfer in food and biological materials

    Science.gov (United States)

    In this chapter, we first define the basic radiometric quantities that are needed for describing light propagation in food and biological materials. Radiative transfer theory is then derived, according to the principle of the conservation of energy. Because the radiative transfer theory equation is ...

  19. Chemistry as a prism: a review of light-emitting materials having tunable emission wavelengths.

    Science.gov (United States)

    Kim, Eunha; Park, Seung Bum

    2009-11-02

    Photoluminescent materials have been extensively applied in various fields of science because of their numerous advantages, such as excellent sensitivity, good specificity, a large linear range of analysis, ease of handling, and so on. Many strategies have been used to understand and manipulate the photophysical properties of photoluminescent materials. This Focus Review describes recent progress focused on tuning the photophysical properties, especially the emission wavelengths of pi-conjugated oligomers, photoluminescent organometallic complexes, and fluorescent organic dyes by chemical modification.

  20. Hexaazatrinaphthylene Derivatives: Efficient Electron-Transporting Materials with Tunable Energy Levels for Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Zhao, Dongbing; Zhu, Zonglong; Kuo, Ming-Yu; Chueh, Chu-Chen; Jen, Alex K-Y

    2016-07-25

    Hexaazatrinaphthylene (HATNA) derivatives have been successfully shown to function as efficient electron-transporting materials (ETMs) for perovskite solar cells (PVSCs). The cells demonstrate a superior power conversion efficiency (PCE) of 17.6 % with negligible hysteresis. This study provides one of the first nonfullerene small-molecule-based ETMs for high-performance p-i-n PVSCs.

  1. Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials

    Science.gov (United States)

    Yu, Woo Jong; Liu, Yuan; Zhou, Hailong; Yin, Anxiang; Li, Zheng; Huang, Yu; Duan, Xiangfeng

    2013-12-01

    Layered materials of graphene and MoS2, for example, have recently emerged as an exciting material system for future electronics and optoelectronics. Vertical integration of layered materials can enable the design of novel electronic and photonic devices. Here, we report highly efficient photocurrent generation from vertical heterostructures of layered materials. We show that vertically stacked graphene-MoS2-graphene and graphene-MoS2-metal junctions can be created with a broad junction area for efficient photon harvesting. The weak electrostatic screening effect of graphene allows the integration of single or dual gates under and/or above the vertical heterostructure to tune the band slope and photocurrent generation. We demonstrate that the amplitude and polarity of the photocurrent in the gated vertical heterostructures can be readily modulated by the electric field of an external gate to achieve a maximum external quantum efficiency of 55% and internal quantum efficiency up to 85%. Our study establishes a method to control photocarrier generation, separation and transport processes using an external electric field.

  2. Phase Change Materials (PCM) fabricated in vertical structures for reconfigurable and tunable circuits

    Science.gov (United States)

    Barajas, Eduardo; Coutu, Ronald A.

    2014-03-01

    Germanium Telluride (GeTe) can be described as a non-volatile (latching state) phase change material (PCM) in memory applications. GeTe also exhibits a volatile (reversible state) region when heated and cooled between 100-180 °C. At temperatures higher than 185 °C the material crystallizes and "latches" until a temperature near to its melting point (725 °C) is reached and cooled rapidly (quenching). Germanium Antimony Telluride (GeSbTe) or also known as GST has similar characteristics as GeTe. GST also exhibits a volatile (reversible state) region when heated and cooled between 100-150 °C. GST crystallizes at 155 °C and its melting point is 600 °C. This paper demonstrates the feasibility of fabricating radio frequency (RF) devices of phase change materials (PCM) and it also presents a comparison between amorphous and crystalline PCMs in the RF spectrum. Previous work focuses on exploiting GeTe and GST as nonvolatile materials in memory applications, and also on characterizing them for their electrical and mechanical properties. The approach here focuses on fabricating RF devices and analyzing their responses. A simulation with resistor-capacitor (RC) and resistor-inductor (RL) circuits is presented to represent the response of the RF devices under testing. The fabrication process includes two-layer and four-layer devices on the Si wafer. PCMs are sputtered and the test pads are deposited using electron beam evaporation. Results show that these RF devices alone can serve as a low pass filter with a cutoff frequency of 10 MHz.

  3. Tunable photonic band-gaps in one-dimensional photonic crystals containing linear graded index material

    Science.gov (United States)

    Singh, Bipin K.; Kumar, Pawan; Pandey, Praveen C.

    2014-12-01

    We have demonstrated control of the photonic band gaps (PBGs) in 1-D photonic crystals using linear graded index material. The analysis of PBG has been done in THz region by considering photonic crystals in the form of ten periods of second, third and fourth generation of the Fibonacci sequence as unit cell. The unit cells are constituted of two kinds of layers; one is taken of linear graded index material and other of normal dielectric material. For this investigation, we used a theoretical model based on transfer matrix method. We have obtained a large number of PBGs and their bandwidths can be tuned by changing the grading profile and thicknesses of linear graded index layers. The number of PBGs increases with increase in the thicknesses of layers and their bandwidths can be controlled by the contrast of initial and final refractive index of the graded layers. In this way, we provide more design freedom for photonic devices such as reflectors, filters, optical sensors, couplers, etc.

  4. FDTD Simulation of Exposure of Biological Material to Electromagnetic Nanopulses

    CERN Document Server

    Simicevic, N; Simicevic, Neven; Haynie, Donald T

    2004-01-01

    Ultra-wideband (UWB) electromagnetic pulses of nanosecond duration, or nanopulses, are of considerable interest to the communications industry and are being explored for various applications in biotechnology and medicine. The propagation of a nanopulse through biological matter has been computed in the time domain using the finite difference-time domain method (FDTD). The approach required existing Cole-Cole model-based descriptions of dielectric properties of biological matter to be re-parametrized using the Debye model, but without loss of accuracy. The approach has been applied to several tissue types. Results show that the electromagnetic field inside a biological tissue depends on incident pulse rise time and width. Rise time dominates pulse behavior inside a tissue as conductivity increases. It has also been found that the amount of energy deposited by 20 $kV/m$ nanopulses is insufficient to change the temperature of the exposed material for the pulse repetition rates of 1 $MHz$ or less.

  5. Tunable omnidirectional multichannel filters based on dual-defective photonic crystals containing negative-index materials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yihang, E-mail: kallenmail@sina.co [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China)

    2009-04-07

    Multiple defect modes may generate in one-dimensional dual-defective photonic crystals containing negative-index materials. The interference between the two kinds of defect states of the proposed structure is avoided. Therefore, the frequency, frequency interval and number of the defect modes corresponding to different kinds of defects can be tuned independently as desired. These defect modes inside the zero n-bar gap are insensitive to the incident angle. It thus opens a promising way to fabricate omnidirectional multichannel filters with specific channels.

  6. Semiconductor Nanocrystals Hybridized with Functional Ligands: New Composite Materials with Tunable Properties

    Directory of Open Access Journals (Sweden)

    Nathan I. Hammer

    2010-01-01

    Full Text Available Semiconductor nanocrystals hybridized with functional ligands represent an important new class of composite nanomaterials. The development of these new nanoscale building blocks has intensified over the past few years and offer significant advantages in a wide array of applications. Functional ligands allow for incorporation of nanocrystals into areas where their unique photophysics can be exploited. Energy and charge transfer between the ligands and the nanocrystal also result in enhanced physical properties that can be tuned by the choice of ligand architecture. Here, progress in the development and applications involving this new class of composite materials will be discussed.

  7. Synthesis and characterization of lignin-based carbon materials with tunable microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Sabornie [ORNL; Clingenpeel, Amy [National High Magnetic Field Laboratory (Magnet Lab), Florida; McKenna, Amy [National High Magnetic Field Laboratory (Magnet Lab), Florida; Rios, Orlando [ORNL; Johs, Alexander [ORNL

    2013-01-01

    Lignin-based carbons can be used as a low-cost alternative to graphite and petroleum-based carbons enabling the production of sustainable, functional carbon materials for various applications. The microstructure development of these carbons can be controlled through chemical modification of the lignin precursor and choice of carbonization parameters. In this work, microstructured carbon materials are synthesized from lignin using a combination of chemical modification and carbon fiber processing techniques. Lignin is modified by incorporating different ester groups which results in a precursor highly compatible with melt processing using the fiber extrusion technique and conversion into microstructured carbons by oxidative stabilization and subsequent carbonization. Furthermore, the impact of esterifications on precursor chemistry and carbonizations is investigated. A nuclear magnetic resonance study of modified lignins shows characteristic spectral changes as a result of esterifications. Ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry shows the modification process does not affect the polymeric character of the lignin backbone. Esterifications result in moderate shifts in O:C and H:C ratios. Thermogravimetric analysis of lignins reveals distinct differences in mass loss trends during oxidations and carbonizations.

  8. Diffusion theory in biology: a relic of mechanistic materialism.

    Science.gov (United States)

    Agutter, P S; Malone, P C; Wheatley, D N

    2000-01-01

    Diffusion theory explains in physical terms how materials move through a medium, e.g. water or a biological fluid. There are strong and widely acknowledged grounds for doubting the applicability of this theory in biology, although it continues to be accepted almost uncritically and taught as a basis of both biology and medicine. Our principal aim is to explore how this situation arose and has been allowed to continue seemingly unchallenged for more than 150 years. The main shortcomings of diffusion theory will be briefly reviewed to show that the entrenchment of this theory in the corpus of biological knowledge needs to be explained, especially as there are equally valid historical grounds for presuming that bulk fluid movement powered by the energy of cell metabolism plays a prominent note in the transport of molecules in the living body. First, the theory's evolution, notably from its origins in connection with the mechanistic materialist philosophy of mid nineteenth century physiology, is discussed. Following this, the entrenchment of the theory in twentieth century biology is analyzed in relation to three situations: the mechanism of oxygen transport between air and mammalian tissues; the structure and function of cell membranes; and the nature of the intermediary metalbolism, with its implicit presumptions about the intracellular organization and the movement of molecules within it. In our final section, we consider several historically based alternatives to diffusion theory, all of which have their precursors in nineteenth and twentieth century philosophy of science.

  9. Tunable Bloch Wave Resonances and Bloch Gaps in Uniform Materials with Reconfigurable Boundary Profiles

    Science.gov (United States)

    Pogrebnyak, Victor A.; Furlani, Edward P.

    2016-05-01

    We study wave propagation in uniform materials with periodic boundary profiles and introduce for the first time Bloch resonances and Bloch gaps. Bloch resonances are due to transverse phase matching, i.e., the coupling of two transverse standing waves corresponding to different harmonics. These are distinct from well-known Bragg resonances that result from longitudinal phase matching. We show that Bloch gaps can be engineered over the entire first Brillouin zone up to an infinite wavelength, i.e., kx=0 , where kx is the wave number in the direction of propagation. This is in contrast to Bragg gaps that open at a fixed wavelength, twice the period of the structure. Bloch resonances and gaps can be tuned by reconfiguring the boundary profile and we derive analytical expressions that predict these phenomena when the amplitude of the profile is small. The theory is fundamental as it broadly applies to wave phenomena that span the quantum to continuum scale with applications that range from condensed matter to acoustics. We validate the theory experimentally for the electromagnetic field at GHz frequencies. We also discuss potential photonic and electronic applications of the theory such as a white-light distributed feedback laser and a two-dimensional electron gas transistor.

  10. Interfacing materials science and biology for drug carrier design.

    Science.gov (United States)

    Such, Georgina K; Yan, Yan; Johnston, Angus P R; Gunawan, Sylvia T; Caruso, Frank

    2015-04-08

    Over the last ten years, there has been considerable research interest in the development of polymeric carriers for biomedicine. Such delivery systems have the potential to significantly reduce side effects and increase the bioavailability of poorly soluble therapeutics. The design of carriers has relied on harnessing specific variations in biological conditions, such as pH or redox potential, and more recently, by incorporating specific peptide cleavage sites for enzymatic hydrolysis. Although much progress has been made in this field, the specificity of polymeric carriers is still limited when compared with their biological counterparts. To synthesize the next generation of carriers, it is important to consider the biological rationale for materials design. This requires a detailed understanding of the cellular microenvironments and how these can be harnessed for specific applications. In this review, several important physiological cues in the cellular microenvironments are outlined, with a focus on changes in pH, redox potential, and the types of enzymes present in specific regions. Furthermore, recent studies that use such biologically inspired triggers to design polymeric carriers are highlighted, focusing on applications in the field of therapeutic delivery.

  11. Advanced Tomography Techniques For Inorganic, Organic, and Biological Materials

    Energy Technology Data Exchange (ETDEWEB)

    Evans, James E.; Friedrich, Heiner

    2016-07-01

    Three-dimensional (3D) tomography using electrons and x-rays has pushed our understanding of the micro- and nanoscale spatial organization for biological, organic and inorganic materials. While significant impact has already been realized from tomography applications, new advanced methods are quickly expanding the versatility of this approach to better link structure, composition and function of complex 3D assemblies across multiple scales. In this article we highlight several frontiers where new developments in tomography are empowering all new science across biology, chemistry and physics. The 5 articles that appear in this MRS Bulletin Issue describe in detail these latest developments in analytical electron tomography, atomic resolution electron tomography, advanced recording schemes in scanning transmission electron (STEM) tomography, cryo-STEM tomography of whole cells, and multiscale correlative tomography.

  12. DNASU plasmid and PSI:Biology-Materials repositories: resources to accelerate biological research.

    Science.gov (United States)

    Seiler, Catherine Y; Park, Jin G; Sharma, Amit; Hunter, Preston; Surapaneni, Padmini; Sedillo, Casey; Field, James; Algar, Rhys; Price, Andrea; Steel, Jason; Throop, Andrea; Fiacco, Michael; LaBaer, Joshua

    2014-01-01

    The mission of the DNASU Plasmid Repository is to accelerate research by providing high-quality, annotated plasmid samples and online plasmid resources to the research community through the curated DNASU database, website and repository (http://dnasu.asu.edu or http://dnasu.org). The collection includes plasmids from grant-funded, high-throughput cloning projects performed in our laboratory, plasmids from external researchers, and large collections from consortia such as the ORFeome Collaboration and the NIGMS-funded Protein Structure Initiative: Biology (PSI:Biology). Through DNASU, researchers can search for and access detailed information about each plasmid such as the full length gene insert sequence, vector information, associated publications, and links to external resources that provide additional protein annotations and experimental protocols. Plasmids can be requested directly through the DNASU website. DNASU and the PSI:Biology-Materials Repositories were previously described in the 2010 NAR Database Issue (Cormier, C.Y., Mohr, S.E., Zuo, D., Hu, Y., Rolfs, A., Kramer, J., Taycher, E., Kelley, F., Fiacco, M., Turnbull, G. et al. (2010) Protein Structure Initiative Material Repository: an open shared public resource of structural genomics plasmids for the biological community. Nucleic Acids Res., 38, D743-D749.). In this update we will describe the plasmid collection and highlight the new features in the website redesign, including new browse/search options, plasmid annotations and a dynamic vector mapping feature that was developed in collaboration with LabGenius. Overall, these plasmid resources continue to enable research with the goal of elucidating the role of proteins in both normal biological processes and disease.

  13. Access and benefit sharing of Antarctica's biological material.

    Science.gov (United States)

    Puig-Marcó, Roser

    2014-10-01

    Searching and sampling of Antarctic Biological Material (ABM) is happening with no explicit regulation on access and benefit sharing requirements. Patents already exist on inventions stemming from Antarctic living organisms. The Antarctic Treaty System (ATS) provides mechanisms to ensure that scientific knowledge and data generated from the collection and use of ABM are shared, although commercialization might be a threat to this free exchange of scientific knowledge. Some of the underlying problems regarding the access and benefit sharing of ABM are that under the ATS there are gaps concerning definitions, access to specimens, benefit sharing, commercialization and reporting issues. The Antarctic Treaty Consultative Parties (ATCPs) have decided that the Antarctic Treaty Consultative Meeting (ATCM) is the competent body to discuss the matter, and the ATS is the appropriate framework for managing the collection of biological material in the Antarctic Treaty area and for considering its use. Nevertheless, opinions diverge as to the need for more specific rules on access and benefit sharing other than that already resulting from the obligation to give prior notification and share scientific results.

  14. Laser-matter structuration of optical and biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Hallo, L., E-mail: hallo@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Mezel, C., E-mail: candice.mezel@cea.fr [CELIA, Universite Bordeaux 1 (France); CEA Le Ripault, 37260 Monts (France); Guillemot, F., E-mail: fabien.guillemot@inserm.fr [UMR 577 INSERM, Universite Bordeaux 2 (France); Chimier, B., E-mail: chimier@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Bourgeade, A., E-mail: antoine.bourgeade@cea.fr [CEA-CESTA, Le Barp (France); Regan, C., E-mail: regan@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Duchateau, G., E-mail: duchateau@celia.u-bordeaux1.fr [CELIA, Universite Bordeaux 1 (France); Souquet, A., E-mail: agnes.souquet@inserm.fr [UMR 577 INSERM, Universite Bordeaux 2 (France); Hebert, D., E-mail: david.hebert@cea.fr [CEA-CESTA, Le Barp (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer In this study we model nanomaterial structuring. Black-Right-Pointing-Pointer The laser energy deposition is discussed first. Black-Right-Pointing-Pointer Full and approximate models are discussed. Black-Right-Pointing-Pointer Dynamic material response is addressed via hydrodynamics. Black-Right-Pointing-Pointer Sild effects are accounted for - Abstract: Interaction of ultrafast laser, i.e. from the femtosecond (fs) to the nanosecond (ns) regime, with initially transparent matter may produce very high energy density hot spots in the bulk as well as at the material surface, depending on focusing conditions. In the fs regime, absorption is due to ionisation of the dielectric, which enables absorption process to begin, and then hydrodynamic to take place. In the ns regime both absorption and hydrodynamic are coupled to each other, which complexifies considerably the comprehension but matter structuration looks similar. A numerical tool including solution of 3D Maxwell equations and a rate equation for free electrons is first compared to some available simple models of laser energy absorption. Then, subsequent material deformation, i.e. structuration, is determined by solving hydrodynamic equations, including or not solid behaviour. We show that nature of the final structures strongly depends on the amount of deposited energy and on the shape of the absorption zone. Then we address some problems related to laser-matter structuration of optical and biological materials in the fs, ps and ns regimes.

  15. Microstrip antenna on tunable substrate

    Science.gov (United States)

    Jose, K. A.; Varadan, Vijay K.; Varadan, Vasundara V.; Mohanan, P.

    1995-05-01

    The tunable patch antenna configurations are becoming popular and attractive in many aspects. This was mainly due to the advent of ferrite thin film technology and tunable substrate materials. The integration of monolithic microwave circuits and antennas are becoming easy today. In the development of magnetic tuning of microstrip patch on ferrite substrate is presented by Rainville and Harackewiez. Radiation characteristics of such antennas are presented by Pozer. Band width and radiation characteristics of such tunable antennas are measured and compared. Usually the substrate losses are considered in the analysis and metallization losses are assumed to be ideal. The analysis of magnetic tunable radiator including metallization and ferrite substrate losses are presented. However, all such tuning and integration of circuits and antennas are mainly on ferrite substrate due to magnetic tuning. Recently, Varadan et al. established that the BaxSr1-xTiO3 series ferroelectric materials such as Barium Strontium Titanate (BST) are well suited for microwave phase shifter applications. It could be possible to change the dielectric constant of these materials more than 50% depending on the BST composition, by changing the applied bias voltage. Also, the porosity of BST can be controlled during processing to produce dielectric constants in the range of 15 to 1500, with some trade off in tunability. In this paper, we are presenting the possibility of designing a microstrip patch antenna on such tunable substrate. Such antennas are having the major advantage of electronic tunability and compact size.

  16. Biology Teacher and Expert Opinions about Computer Assisted Biology Instruction Materials: A Software Entitled Nucleic Acids and Protein Synthesis

    Science.gov (United States)

    Hasenekoglu, Ismet; Timucin, Melih

    2007-01-01

    The aim of this study is to collect and evaluate opinions of CAI experts and biology teachers about a high school level Computer Assisted Biology Instruction Material presenting computer-made modelling and simulations. It is a case study. A material covering "Nucleic Acids and Protein Synthesis" topic was developed as the…

  17. Dielectric properties of tissues and biological materials: a critical review.

    Science.gov (United States)

    Foster, K R; Schwan, H P

    1989-01-01

    We critically review bulk electrical properties of tissues and other biological materials, from DC to 20 GHz, with emphasis on the underlying mechanisms responsible for the properties. We summarize the classical principles behind dielectric relaxation and critically review recent developments in this field. Special topics include a summary of the significant recent advances in theories of counterion polarization effects, dielectric properties of cancer vs. normal tissues, properties of low-water-content tissues, and macroscopic field-coupling considerations. Finally, the dielectric properties of tissues are summarized as empirical correlations with tissue water content in other compositional variables; in addition, a comprehensive table is presented of dielectric properties. The bulk electrical properties of tissues are needed for many bioengineering applications of electric fields or currents, and they provide insight into the basic mechanisms that govern the interaction of electric fields with tissue.

  18. Millimeter wave and terahertz dielectric properties of biological materials

    Science.gov (United States)

    Khan, Usman Ansar

    Broadband dielectric properties of materials can be employed to identify, detect, and characterize materials through their unique spectral signatures. In this study, millimeter wave, submillimeter wave, and terahertz dielectric properties of biological substances inclusive of liquids, solids, and powders were obtained using Dispersive Fourier Transform Spectroscopy (DFTS). Two broadband polarizing interferometers were constructed to test materials from 60 GHz to 1.2 THz. This is an extremely difficult portion of the frequency spectrum to obtain a material's dielectric properties since neither optical nor microwave-based techniques provide accurate data. The dielectric characteristics of liquids such as cyclohexane, chlorobenzene, benzene, ethanol, methanol, 1,4 dioxane, and 10% formalin were obtained using the liquid interferometer. Subsequently the solid interferometer was utilized to determine the dielectric properties of human breast tissues, which are fixed and preserved in 10% formalin. This joint collaboration with the Tufts New England Medical Center demonstrated a significant difference between the dielectric response of tumorous and non-tumorous breast tissues across the spectrum. Powders such as anthrax, flour, talc, corn starch, dry milk, and baking soda have been involved in a number of security threats and false alarms around the globe in the last decade. To be able to differentiate hoax attacks and serious security threats, the dielectric properties of common household powders were also examined using the solid interferometer to identify the powders' unique resonance peaks. A new sample preparation kit was designed to test the powder specimens. It was anticipated that millimeter wave and terahertz dielectric characterization will enable one to clearly distinguish one powder from the other; however most of the powders had relatively close dielectric responses and only Talc had a resonance signature recorded at 1.135 THz. Furthermore, due to

  19. PROTECTION OF WOODEN MATERIALS AGAINST BIOLOGICAL ATTACK BY USING NANOTECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Michal Havrlik

    2015-04-01

    Full Text Available This article is focused on protection of wooden materials by using nanofibrous textiles with biocidal addition, which continues on the work of a group at the Center for Nanotechnology at the Faculty of Civil Engineering in the CTU. Timber is a natural material which is predisposed for biodegradation and therefore it is essential to study suitable and effective protection against microorganisms. Wood is a material susceptible to biological corrosion and therefore it is necessary to protect it. The study compares biocidal efficiency of polymer solution as a coating and as a layer from nanofiber textiles. We used polyvinyl alcohol (PVA as a basic polymer which was enriched by substances from commercial Lignofix E – profi, solution of CuSO4 · 5H2O and AgNO3 and finally colloidal silver as an example of nanoparticles. The final concentration of the biocidal substance was 1 (v/wt% in fiber. The nanofiber textiles are produced on the device Nanospider NS LAB 500 (Elmarco, CR on cylinder rotating electrode. The study was divided into two parts, the first being an agar plate test and the second a test on samples from timber. The mixture of mold was used as the model organism. (Alternaria tenuissima, Pochonia bulbiosa, Trichoderma viride and Acremonium sclerotigenum. Comparison of efficiency between the polymer paint and nanofiber textiles showed no difference. The best results were shown by PVA with an addition of substances from the commercial biocidal treatment Lignofix-E Profi on the agar plate. The difference of result was shown on timbre samples, finding that the best results were with treatment by PVA doped by Silver nitrate. The anticipated results were shown by treatment with non-doped PVA, which does not have any fungicidal protective effect.

  20. Tunable laser optics

    CERN Document Server

    Duarte, FJ

    2015-01-01

    This Second Edition of a bestselling book describes the optics and optical principles needed to build lasers. It also highlights the optics instrumentation necessary to characterize laser emissions and focuses on laser-based optical instrumentation. The book emphasizes practical and utilitarian aspects of relevant optics including the essential theory. This revised, expanded, and improved edition contains new material on tunable lasers and discusses relevant topics in quantum optics.

  1. Estimates of iodine in biological materials by epithermal neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T. (Tokyo Metropolitan Inst. for Neurosciences, Fuchu (Japan)); Kato, T. (Tohoku Univ., Sendai (Japan). Coll. of General Education)

    1982-01-01

    Iodine abundances in NBS biological SRMs and various organs of rats were evaluated by epithermal neutron activation analysis with a boron carbide filter. The detectability of iodine in different biological materials by this method is discussed.

  2. CFD Simulation of Fouling by Biological materials in Membrane Bioreactor

    Directory of Open Access Journals (Sweden)

    Raziye, Ahmadi

    2016-06-01

    Full Text Available In recent years membrane bioreactors filtration is increasingly used in wastewater treatment to enhance the quality of wastewater. The main problem in preventing the widespread use of membrane bioreactor is its congestion which has a severe impact on output flux to time ratio. If solid suspensions with high concentrations exist in the wastewater, this influence will be even more severe. In addition to the suspended solids in the liquid mixture, Extracellular polymeric materials (EPS and soluble microbial products (SMP are also known as basic microbial products that cause membrane fouling. EPS can be calculated within and on the membrane which increases the viscosity of suspended solids in the liquid mixture and increases filtration resistance. SMPs cannot penetrate the pores of the ultra filtration membrane due to the limited size of the pores which would cause fouling in membrane processes. According to the above issues, providing a model that indicates the properties and conditions of formation and destruction of SMP and EPS at the same time seems necessary. In this paper, CFD simulation of biological fouling in membrane bioreactor is provided using Fluent software.

  3. Profile of accidents with biological material at a dental school

    Directory of Open Access Journals (Sweden)

    Sandra Aragão de Almeida Sasamoto

    2014-09-01

    Full Text Available http://dx.doi.org/10.4025/actascihealthsci.v36i1.14976 Current research characterizes the epidemiological profile of accidents with biological material (BM that occurred in a government-run dental school and identifies the post-exposure behavior taken by the injured subjects. The cross-sectional retrospective study comprises professors, students and technical-administration personnel who worked in the laboratory from 2001 to 2008 (n = 566. An electronic questionnaire, prepared by software developed for this purpose, was sent to subjects between May and August 2008 for data collection. Ninety-one (34.2% out of 266 participants reported some type of exposure to BM. There was no difference between the occurrence of accidents according to the subjects’ category (p = 0.496 and sex (p = 0.261. Most of the subjects reported cutaneous exposure (76.9% comprising saliva (68.1% and blood (48.3%. The fingers were the body members most affected. Accidents occurred mostly during clinical (34.1% and surgical (30.8% procedures. Although the use of protection equipments was high (82.9%, only 26.4% of subjects reported the accident and only 28.6% sought immediate help. Most of the injured subjects failed to report the accidents and did not comply with the guidelines. Others trivialized basic behavior such as the interruption of the procedure to seek medical assistance.

  4. Giant and universal magnetoelectric coupling in soft materials and concomitant ramifications for materials science and biology.

    Science.gov (United States)

    Liu, Liping; Sharma, Pradeep

    2013-10-01

    Magnetoelectric coupling-the ability of a material to magnetize upon application of an electric field and, conversely, to polarize under the action of a magnetic field-is rare and restricted to a rather small set of exotic hard crystalline materials. Intense research activity has recently ensued on materials development, fundamental scientific issues, and applications related to this phenomenon. This tantalizing property, if present in adequate strength at room temperature, can be used to pave the way for next-generation memory devices such as miniature magnetic random access memories and multiple state memory bits, sensors, energy harvesting, spintronics, among others. In this Rapid Communication, we prove the existence of an overlooked strain mediated nonlinear mechanism that can be used to universally induce the giant magnetoelectric effect in all (sufficiently) soft dielectric materials. For soft polymer foams-which, for instance, may be used in stretchable electronics-we predict room-temperature magnetoelectric coefficients that are comparable to the best known (hard) composite materials created. We also argue, based on a simple quantitative model, that magnetoreception in some biological contexts (e.g., birds) most likely utilizes this very mechanism.

  5. Organization and diffusion in biological and material fabrication problems

    Science.gov (United States)

    Mangan, Niall Mari

    This thesis is composed of two problems. The first is a systems level analysis of the carbon concentrating mechanism in cyanobacteria. The second presents a theoretical analysis of femtosecond laser melting for the purpose of hyperdoping silicon with sulfur. While these systems are very distant, they are both relevant to the development of alternative energy (production of biofuels and methods for fabricating photovoltaics respectively). Both problems are approached through analysis of the underlying diffusion equations. Cyanobacteria are photosynthetic bacteria with a unique carbon concentrating mechanism (CCM) which enhances carbon fixation. A greater understanding of this mechanism would offer new insights into the basic biology and methods for bioengineering more efficient biochemical reactions. The molecular components of the CCM have been well characterized in the last decade, with genetic analysis uncovering both variation and commonalities in CCMs across cyanobacteria strains. Analysis of CCMs on a systems level, however, is based on models formulated prior to the molecular characterization. We present an updated model of the cyanobacteria CCM, and analytic solutions in terms of the various molecular components. The solutions allow us to find the parameter regime (expression levels, catalytic rates, permeability of carboxysome shell) where carbon fixation is maximized and oxygenation is minimized. Saturation of RuBisCO, maximization of the ratio of CO2 to O2, and staying below or at the saturation level for carbonic anhydrase are all needed for maximum efficacy. These constraints limit the parameter regime where the most effective carbon fixation can occur. There is an optimal non-specific carboxysome shell permeability, where trapping of CO2 is maximized, but HCO3 - is not detrimentally restricted. The shell also shields carbonic anhydrase activity and CO2 → HCO3- conversion at the thylakoid and cell membrane from one another. Co-localization of carbonic

  6. Distinguishability of Biological Material Using Ultraviolet Multi-Spectral Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Gray, P.C.; Heinen, R.J.; Rigdon, L.D.; Rosenthal, S.E.; Shokair, I.R.; Siragusa, G.R.; Tisone, G.C.; Wagner, J.S.

    1998-10-14

    Recent interest in the detection and analysis of biological samples by spectroscopic methods has led to questions concerning the degree of distinguishability and biological variability of the ultraviolet (W) fluorescent spectra from such complex samples. We show that the degree of distinguishability of such spectra is readily determined numerically.

  7. Deciphering the language between biological and synthetic materials

    Directory of Open Access Journals (Sweden)

    Paolo Antonio Netti

    2014-06-01

    Full Text Available Chemical signals propagating through aqueous environment are at the basis of the language utilized by living systems to exchange information. In the last years, molecular biology has partly disclosed the grammar and the syntax of this complex language revealing the fascinating world of molecular communication that is the foundation of biological development.

  8. Tunable surface properties from bioinspired polymers

    Science.gov (United States)

    van Zoelen, Wendy; Rosales, Adrianne; Murnen, Hannah; Zuckermann, Ronald; Segalman, Rachel

    2011-03-01

    Anti-fouling properties can be derived from patterned or ``ambiguous'' surfaces displaying multiple surface properties. Biological polymers with precisely controlled chain shapes and self-assembled structures are attractive materials for these applications, in which tunability is of great importance. We have investigated the surface properties of polypeptoids, a class of non-natural biomimetic polymers based on an N-substituted glycine backbone, that combine many of the advantageous properties of bulk polymers with those of synthetically produced proteins. Polypeptoids are of particular interest as they can be made in a sequence controlled fashion with functionalities already known to impart fouling-resistance (ethers, zwitterions, hydrophobicity, and nanoscale patterning). We demonstrate their surface stability and processibility from the standpoint of coating performance and also discuss controlled self-assembly of these materials. Used strategies include mediation of crystallization by incorporating chain defects and specific interactions.

  9. Method for Forming Copious (F sub 2(+))A Centers in Certain Stable, Broadly-Tunable Laser-Active Materials.

    Science.gov (United States)

    iodide, Rubidium iodide lithium crystals and other comparable crystalline materials , especially materials doped with lithium (Li). A principal object of...ion centers in Kl:Li and RbI:Li, or in comparable crystalline materials ; by growing, coloring, and annealing the K::Li or the RbI:Li crystals in nitrogen-free inert (e.g., argon) atmospheres.

  10. ``Standoff Biofinder'' for Fast, Noncontact, Nondestructive, Large-Area Detection of Biological Materials for Planetary Exploration

    Science.gov (United States)

    Misra, Anupam K.; Acosta-Maeda, Tayro E.; Sharma, Shiv K.; McKay, Christopher P.; Gasda, Patrick J.; Taylor, G. Jeffrey; Lucey, Paul G.; Flynn, Luke; Nurul Abedin, M.; Clegg, Samuel M.; Wiens, Roger

    2016-09-01

    We developed a prototype instrument called the Standoff Biofinder, which can quickly locate biological material in a 500 cm2 area from a 2 m standoff distance with a detection time of 0.1 s. All biogenic materials give strong fluorescence signals when excited with UV and visible lasers. In addition, the luminescence decay time of biogenic compounds is much shorter (biofluorescent materials to obtain real-time fluorescence images that show the locations of biological materials among luminescent minerals in a geological context. The Standoff Biofinder instrument will be useful for locating biological material during future NASA rover, lander, and crewed missions. Additionally, the instrument can be used for nondestructive detection of biological materials in unique samples, such as those obtained by sample return missions from the outer planets and asteroids. The Standoff Biofinder also has the capacity to detect microbes and bacteria on space instruments for planetary protection purposes.

  11. Photoconversion of gasified organic materials into biologically-degradable plastics

    Science.gov (United States)

    Weaver, Paul F.; Maness, Pin-Ching

    1993-01-01

    A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer.

  12. Photoconversion of gasified organic materials into biologically-degradable plastics

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.F.; Pinching Maness.

    1993-10-05

    A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer. 3 figures.

  13. Preparation and biological evaluations of PLA/chitosan composite materials

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chang-ren; LI Lihua; DING Shan

    2001-01-01

    @@ INTRODUCTION Polylactic acid (PLA) is a biodegradable material that is hontoxic and biocompatible. However, as scaffold materials, PLA has several obvious weaknesses:biodegrading too fast, acidic degradation product, and hydrophobic. When PLA isplanted in the body, the degradation takes place synchronously.

  14. Signal sensitivity of alternating current potential drop measurement for crack detection of conductive substrate with tunable coating materials through finite element modeling

    Science.gov (United States)

    Sandeep Rao, Simha; Liu, Ming; Peng, Fei; Zhang, Bo; Zhao, Huijuan

    2016-12-01

    We adopt a finite element numerical modeling approach to investigate the electromagnetic coupling effect of two parallel electric conductors with tunable electric conductivity σ and magnetic permeability μ. For two parallel conductors C and S (μ C   ṡ  σ C   ≤  μ S   ṡ  σ S), we find that the shape of current density profile of conductor S is dependent on the product of μ C   ṡ  σ C, while the magnitude is determined by the AC current frequency f. On the other hand, the frequency f affects not only the shape but also the magnitude of the current density profile of conductor C. We further adopt a coplanar model to investigate the signal sensitivity of alternating current potential drop (ACPD) measurement for both surface crack and inner crack detection. We find that with modified coating materials (lower electric conductivity and higher magnetic permeability, compared with the substrate material properties), the crack detection signal sensitivity can be greatly enhanced for both the cracks within the coating and at the coating/substrate interface, where cracks are most commonly encountered in real situations.

  15. [Biological decontamination of the imprints obtained from different dental materials].

    Science.gov (United States)

    Brekhlichuk, P P; Petrov, V O; Bati, V V; Levchuk, O B; Boĭko, N V

    2013-01-01

    Microbiological contamination of the imprints made of alginate ("Ypeen") and silicone material ("Speedex") with and without the correction supplement has been investigated. Streptococcus and Staphylococcus have been estimated to be the most survivable species on the imprint surface, however their concentration differ depending on the type of imprints' material. The strains resistant to antibiotics dominated among all the isolated microorganisms. Bacterial preparations based on Bacillus - Biosporin and Subalin and some extracts of edible plants, fruits and berries can be used in dentistry for the decontamination of imprints obtained by the use of different materials.

  16. Bioreceptivity evaluation of cementitious materials designed to stimulate biological growth.

    Science.gov (United States)

    Manso, Sandra; De Muynck, Willem; Segura, Ignacio; Aguado, Antonio; Steppe, Kathy; Boon, Nico; De Belie, Nele

    2014-05-15

    Ordinary Portland cement (OPC), the most used binder in construction, presents some disadvantages in terms of pollution (CO2 emissions) and visual impact. For this reason, green roofs and façades have gain considerable attention in the last decade as a way to integrate nature in cities. These systems, however, suffer from high initial and maintenance costs. An alternative strategy to obtain green facades is the direct natural colonisation of the cementitious construction materials constituting the wall, a phenomenon governed by the bioreceptivity of such material. This work aims at assessing the suitability of magnesium phosphate cement (MPC) materials to allow a rapid natural colonisation taking carbonated OPC samples as a reference material. For that, the aggregate size, the w/c ratio and the amount of cement paste of mortars made of both binders were modified. The assessment of the different bioreceptivities was conducted by means of an accelerated algal fouling test. MPC samples exhibited a faster fouling compared to OPC samples, which could be mainly attributed to the lower pH of the MPC binder. In addition to the binder, the fouling rate was governed by the roughness and the porosity of the material. MPC mortar with moderate porosity and roughness appears to be the most feasible material to be used for the development of green concrete walls.

  17. Agricultural biological reference materials for analytical quality control

    Energy Technology Data Exchange (ETDEWEB)

    Ihnat, M.

    1986-01-01

    Cooperative work is under way at Agriculture Canada, US Department of Agriculture, and US National Bureau of Standards in an attempt to fill some of the gaps in the world repertoire of reference materials and to provide much needed control materials for laboratories' day to day operations. This undertaking involves the preparation and characterization of a number of agricultural and food materials for data quality control for inorganic constituents. Parameters considered in the development of these materials were material selection based on importance in commerce and analysis; techniques of preparation, processing, and packaging; physical and chemical characterization; homogeneity testing and quantitation (certification). A large number of agricultural/food products have been selected to represent a wide range of not only levels of sought-for constituents (elements) but also a wide range of matrix components such as protein, carbohydrate, dietary fiber, fat, and ash. Elements whose concentrations are being certified cover some two dozen major, minor, and trace elements of nutritional, toxicological, and environmental significance.

  18. Biomolecular coronas provide the biological identity of nanosized materials

    NARCIS (Netherlands)

    Monopoli, Marco P; Åberg, Christoffer; Salvati, Anna; Dawson, Kenneth A

    2012-01-01

    The search for understanding the interactions of nanosized materials with living organisms is leading to the rapid development of key applications, including improved drug delivery by targeting nanoparticles, and resolution of the potential threat of nanotechnological devices to organisms and the en

  19. Fragment Produced by Nuclear Reaction of Heavy Ions Interacted with Tissue-equivalent Biological Material

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In heavy ion therapy and radiation biological effects the nuclear fragments from the heavy ion collisions may cause a significant alteration of the radiation field. Nuclear collision between beam particles and tissue nuclei along the penetration path of high-energy ions in tissue or biological-equivalent material causes a loss

  20. Synthesis and Color-tunable Fluorescence Properties of Schiff Base Zinc (II) Complexes Used as Electroluminescent Materials

    Institute of Scientific and Technical Information of China (English)

    Yi YI; Xiao Qiang WEI; Ming Gui XIE; Zhi Yun LU

    2004-01-01

    Four kinds of bis(N-alkylsalicylaldiminato) zinc(II) complexes were synthesized, and their molecular structures were determined by FT-IR and elemental analysis. Their photoluminescence properties were determined, which indicated that they could emit strong fluorescence varying from blue to yellow to reddish orange depending on their different molecular structures. They had good thermostability, solubility and film forming capability, and can be used as organic electroluminescent materials. These new complexes may afford the feasibility to realize full-color display with materials based on similar molecular structures.

  1. New improved method for evaluation of growth by food related fungi on biologically derived materials

    DEFF Research Database (Denmark)

    Bergenholtz, Karina P.; Nielsen, Per Væggemose

    2002-01-01

    as a new method where 10 mul of a spore suspension is placed in a spot on the test sample. The new method gave additional information about fungal growth on biologically derived materials, revealing a clear difference between survival and growth. PHB and PIA turned out to be most suitable for food......Biologically derived materials, obtained as commercial and raw materials (Polylactate (PLA), Polyhydroxybutyrate (PHB), potato, wheat and corn starch) were tested for their ability to support fungal growth using a modified ASTM G21-96 (American Society for Testing and Materials) standard as well...

  2. [Materials for the substantiation of the biological MAC of benzene].

    Science.gov (United States)

    Ulanova, I P; Avilova, G G; Karpukhina, E A; Karimova, L K; Boĭko, V I; Makar'eva, L M

    1990-09-01

    Relatively great amount of benzene-originated phenol, the presence of a definite relationship between phenol amount in the urine and benzene content in the air indicate that it is reasonable to use a phenol sample as an exposure test. To determine the intensity of benzene exposure, data on phenol content in the urine of people working at some big-tonnage enterprises has been analyzed. On the basis of the national and foreign literature data on the correlation between the phenol urine concentration and the level of benzene exposure a regression equation was deduced, which has made it possible to calculate phenol content in the urine on the level of average working day benzene concentration adopted in the USSR. This value equals 15 mg/l, which was proposed as a biological benzene MAC.

  3. Analysis of biological materials using a nuclear microprobe

    Science.gov (United States)

    Mulware, Stephen Juma

    The use of nuclear microprobe techniques including: Particle induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) for elemental analysis and quantitative elemental imaging of biological samples is especially useful in biological and biomedical research because of its high sensitivity for physiologically important trace elements or toxic heavy metals. The nuclear microprobe of the Ion Beam Modification and Analysis Laboratory (IBMAL) has been used to study the enhancement in metal uptake of two different plants. The roots of corn (Zea mays) have been analyzed to study the enhancement of iron uptake by adding Fe (II) or Fe(III) of different concentrations to the germinating medium of the seeds. The Fe uptake enhancement effect produced by lacing the germinating medium with carbon nanotubes has also been investigated. The aim of this investigation is to ensure not only high crop yield but also Fe-rich food products especially from calcareous soil which covers 30% of world's agricultural land. The result will help reduce iron deficiency anemia, which has been identified as the leading nutritional disorder especially in developing countries by the World Health Organization. For the second plant, Mexican marigold (Tagetes erecta ), the effect of an arbuscular mycorrhizal fungi (Glomus intraradices ) for the improvement of lead phytoremediation of lead contaminated soil has been investigated. Phytoremediation provides an environmentally safe technique of removing toxic heavy metals (like lead), which can find their way into human food, from lands contaminated by human activities like mining or by natural disasters like earthquakes. The roots of Mexican marigold have been analyzed to study the role of arbuscular mycorrhizal fungi in enhancement of lead uptake from the contaminated rhizosphere.

  4. A novel hybrid material: an inorganic silica aerogel core encapsulated with a tunable organic alginate aerogel layer

    OpenAIRE

    Ülker, Zeynep; Erkey, Can

    2014-01-01

    A novel layered material consisting of a silica aerogel core encapsulated by an alginate aerogel layer was developed. The components of the hybrid aerogel had the high surface area and high porosity of pure aerogels which should lead to development of new layered systems for a wide variety of applications.

  5. Chemical, Biological, and Radiological Contamination Survivability: Material Effects Testing

    Science.gov (United States)

    2012-06-22

    Description of test specimen (i.e., surface condition (pretest), paint type, paint thickness (number of coats), paint condition, and surface cleanliness ), with...c. The surface condition, surface cleanliness , corrosion, materials of construction, variance from standard painting, and paint condition will be...and surface cleanliness ), with photographs will be TOP 08-2-502 22 June 2012 22 recorded. The test specimen shall be delivered, constructed

  6. Low cost materials of construction for biological processes: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-13

    The workshop was held, May 1993 in conjunction with the 15th Symposium on Biotechnology for Fuels and Chemicals. The purpose of this workshop was to present information on the biomass to ethanol process in the context of materials selection and through presentation and discussion, identify promising avenues for future research. Six technical presentations were grouped into two sessions: process assessment and technology assessment. In the process assessment session, the group felt that the pretreatment area would require the most extensive materials research due the complex chemical, physical and thermal environment. Discussion centered around the possibility of metals being leached into the process stream and their effect on the fermentation mechanics. Linings were a strong option for pretreatment assuming the economics were favorable. Fermentation was considered an important area for research also, due to the unique complex of compounds and dual phases present. Erosion in feedstock handling equipment was identified as a minor concern. In the technology assessment session, methodologies in corrosion analysis were presented in addition to an overview of current coatings/linings technology. Widely practiced testing strategies, including ASTM methods, as well as novel procedures for micro-analysis of corrosion were discussed. Various coatings and linings, including polymers and ceramics, were introduced. The prevailing recommendations for testing included keeping the testing simple until the problem warranted a more detailed approach and developing standardized testing procedures to ensure the data was reproducible and applicable. The need to evaluate currently available materials such as coatings/linings, carbon/stainless steels, or fiberglass reinforced plastic was emphasized. It was agreed that economic evaluation of each material candidate must be an integral part of any research plan.

  7. Status of study on biological and toxicological effects of nanoscale materials

    Institute of Scientific and Technical Information of China (English)

    WANG; Bing; FENG; Weiyue; ZHAO; Yuliang; XING; Gengmei; CH

    2005-01-01

    Because the physical and chemical properties of nanosized materials mostly differ from the existing microsized materials, their potential impacts on human health and the environment will be topics under the serious discussions in press and in a number of international scientific journals. We analyze and summarize the existing data of the experimental study on the biological activities and adverse effects of nanoscale materials/particles including single wall carbon nanotubes, multi wall carbon nanotubes, titanium oxide and iron powders. Though some biological behaviors of nanoscale materials observed cannot be understood on the basis of the current knowledge, as the existing data are mostly preliminary, it is too early to make some exclusive conclusions on biological activities (or the toxicity) of any of nanoscale materials. The experimental techniques, the current topics, and the future research directions for this new research field are also discussed.

  8. Analysis of hazardous biological material by MALDI mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    KL Wahl; KH Jarman; NB Valentine; MT Kingsley; CE Petersen; ST Cebula; AJ Saenz

    2000-03-21

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) has become a valuable tool for analyzing microorganisms. The speed with which data can be obtained from MALDI-MS makes this a potentially important tool for biological health hazard monitoring and forensic applications. The excitement in the mass spectrometry community in this potential field of application is evident by the expanding list of research laboratories pursuing development of MALDI-MS for bacterial identification. Numerous research groups have demonstrated the ability to obtain unique MALDI-MS spectra from intact bacterial cells and bacterial cell extracts. The ability to differentiate strains of the same species has been investigated. Reproducibility of MALDI-MS spectra from bacterial species under carefully controlled experimental conditions has also been demonstrated. Wang et al. have reported on interlaboratory reproducibility of the MALDI-MS analysis of several bacterial species. However, there are still issues that need to be addressed, including the careful control of experimental parameters for reproducible spectra and selection of optimal experimental parameters such as solvent and matrix.

  9. Molecular depth profiling of organic and biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, John S. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom)]. E-mail: John.Fletcher@manchester.ac.uk; Conlan, Xavier A. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom); Lockyer, Nicholas P. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom); Vickerman, John C. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M60 1QD (United Kingdom)

    2006-07-30

    Atomic depth profiling using secondary ion mass spectrometry, SIMS, is common in the field micro-electronics; however, the generation of molecular information as a function of sample depth is difficult due to the accumulation of damage both on and beneath the sample surface. The introduction of polyatomic ion beams such as SF{sub 5} and C{sub 60} have raised the possibility of overcoming this problem as they deposit the majority of their energy in the upper surface of the sample resulting in increased sputter yields but with a complimentary reduction in sub-surface damage accumulation. In this paper we report the depth profile analysis of the bio-polymer polycaprolactone, PCL, using the polyatomic ions Au{sub 3}{sup +} and C{sub 60}{sup +} and the monoatomic Au{sup +}. Results are compared to recent analysis of a similar sample using SF{sub 5}{sup +}. C{sub 60}{sup +} depth profiling of cellulose is also demonstrated, an experiment that has been reported as unsuccessful when attempted with SF{sub 5}{sup +} implications for biological analysis are discussed.

  10. Preparation of Biologically Active Materials by Biomimetic Process

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to form the apatite nuclei on a surface of the substrate,the substrate was placed on or in CaO,SiO2-based glass particles which were soaked in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma,and to make the apatite nuclei grow on the substrate in situ,the substrate was soaked in another solution highly supersaturated with respect to the apatite. The induction period for the apatite nucleation varied from 0 to 4 days depending on the kind of the substrate. The thickness of the apatite layer increases linearly with increasing soaking time in the second solution.The rate of growth of the apatite layer increases with increasing degree of the supersaturation and temperature of the second solution, reaching 7um/d in a solution with ion concentrations which is as 1.5 times as those of the simulated body fluid at 60 ℃. The adhesive strength of the apatite layer to the substrate varies depending on the kind and roughness of the substrate. Polyethyleneterephthalate and polyethersulfone plates abraded with No.400 diamond paste show adhesive strengths of as high as 4 MPa. This type of composite of the bone-like apatite with metals, ceramics and organic polymers might be useful not only as highly bioactive hard tissue-repairing materials with analogous mechanical properties to those of the hard tissues, but also as highly biocompatible soft tissue-repairing materials with ductility.

  11. Design of Tunable Superconducting Metamaterials

    Science.gov (United States)

    Trepanier, Melissa; Zhang, Daimeng; Anlage, Steven

    2013-03-01

    Our goal is to create a superconducting metamaterial utilizing deep sub-wavelength meta-atoms with a quickly-tunable index of refraction. To accomplish this we will combine two different materials: an array of rf SQUIDs (with tunable effective permeability) and an array of thin wires interrupted by Josephson junctions (with tunable effective permittivity). These materials have been designed to maximize tunablility in the range easily measured via X-band, Ku-band, and K-band waveguides. Various sizes of rf SQUIDs were designed to be non-hysteretic, be sufficiently insensitive to noise, and to have resonant frequencies ranging from 6.5 - 22 GHz. The wire array was designed so that the inductance of the Josephson junctions can completely cancel the geometric and kinetic inductance of the wires, giving rise to strong tunability. We will present the design considerations and simulation results for this new class of metamaterials. This work is supported by the NSF-GOALI program through grant # ECCS-1158644, and CNAM.

  12. Detection of Biological Materials Using Ion Mobility Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rodacy, P.J.; Sterling, J.P.; Butler, M.A.

    1999-03-01

    Traditionally, Ion Mobility Spectroscopy has been used to examine ions of relatively low molecular weight and high ion mobility. In recent years, however, biomolecules such as bradykinin, cytochrome c, bovine pancreatic trypsin inhibitor (BPTI), apomyoglobin, and lysozyme, have been successfully analyzed, but studies of whole bio-organisms have not been performed. In this study an attempt was made to detect and measure the mobility of two bacteriophages, {lambda}-phage and MS2 using electrospray methods to inject the viruses into the ion mobility spectrometer. Using data from Yeh, et al., which makes a comparison between the diameter of non-biologic particles and the specific particle mobility, the particle mobility for the MS2 virus was estimated to be 10{sup {minus}2} cm{sup 2}/volt-sec. From this mobility the drift time of these particles in our spectrometer was calculated to be approximately 65 msec. The particle mobility for the {lambda}-phage virus was estimated to be 10{sup {minus}3} cm{sup 2}/volt-sec. which would result in a drift time of 0.7 sec. Spectra showing the presence of a viral peak at the expected drift time were not observed. However, changes in the reactant ion peak that could be directly attributed to the presence of the viruses were observed. Virus clustering, excessive collisions, and the electrospray injection method limited the performance of this IMS. However, we believe that an instrument specifically designed to analyze such bioagents and utilizing other injection and ionization methods will succeed in directly detecting viruses and bacteria.

  13. Interspecific variation in beeswax as a biological construction material.

    Science.gov (United States)

    Buchwald, Robert; Breed, Michael D; Greenberg, Alan R; Otis, Gard

    2006-10-01

    Beeswax is a multicomponent material used by bees in the genus Apis to house larvae and store honey and pollen. We characterized the mechanical properties of waxes from four honeybee species: Apis mellifera L., Apis andreniformis L., Apis dorsata L. and two subspecies of Apis cerana L. In order to isolate the material effects from the architectural properties of nest comb, we formed raw wax in to right, circular cylindrical samples, and compressed them in an electromechanical tensometer. From the resulting stress-strain curves, values for yield stress, yield strain, stress and strain at the proportional limit, stiffness, and resilience were obtained. Apis dorsata wax was stiffer and had a higher yield stress and stress at the proportional limit than all of the other waxes. The waxes of A. cerana and A. mellifera had intermediate strength and stiffness, and A. andreniformis wax was the least strong, stiff and resilient. All of the waxes had similar strain values at the proportional limit and yield point. The observed differences in wax mechanical properties correlate with the nesting ecology of these species. A. mellifera and A. cerana nest in cavities that protect the nest from environmental stresses, whereas the species with the strongest and stiffest wax, A. dorsata, constructs relatively heavy nests attached to branches of tall trees, exposing them to substantially greater mechanical forces. The wax of A. andreniformis was the least strong, stiff and resilient, and their nests have low masses relative to other species in the genus and, although not built in cavities, are constructed on lower, often shielded branches that can absorb the forces of wind and rain.

  14. Preparation of two biological reference materials for QUASIMEME inter-laboratory testing

    NARCIS (Netherlands)

    Lohman, M.; Korytar, P.

    2007-01-01

    Two biological materials have been prepared for the Institute for Environmental Studies (IVM), Free University, Amsterdam to be used in QUASIMEME interlaboratory studies. The materials prepared are: 300 tins of homogenized blue mussels from the Waddenzee (QO07-1) and 300 tins of homogenized shrimps

  15. Integrated Design and Simulation of Tunable, Multi-State Structures Fabricated Monolithically with Multi-Material 3D Printing

    Science.gov (United States)

    Chen, Tian; Mueller, Jochen; Shea, Kristina

    2017-01-01

    Multi-material 3D printing has created new opportunities for fabricating deployable structures. We design reversible, deployable structures that are fabricated flat, have defined load bearing capacity, and multiple, predictable activated geometries. These structures are designed with a hierarchical framework where the proposed bistable actuator serves as the base building block. The actuator is designed to maximise its stroke length, with the expansion ratio approaching one when serially connected. The activation force of the actuator is parameterised through its joint material and joint length. Simulation and experimental results show that the bistability triggering force can be tuned between 0.5 and 5.0 N. Incorporating this bistable actuator, the first group of hierarchical designs demonstrate the deployment of space frame structures with a tetrahedron module consisting of three active edges, each containing four serially connected actuators. The second group shows the design of flat structures that assume either positive or negative Gaussian curvature once activated. By flipping the initial configuration of the unit actuators, structures such as a dome and an enclosure are demonstrated. A modified Dynamic Relaxation method is used to simulate all possible geometries of the hierarchical structures. Measured geometries differ by less than 5% compared to simulation results. PMID:28361891

  16. Mechanics of dynamic needle insertion into a biological material.

    Science.gov (United States)

    Mahvash, Mohsen; Dupont, Pierre E

    2010-04-01

    During needle-based procedures, transitions between tissue layers often lead to rupture events that involve large forces and tissue deformations and produce uncontrollable crack extensions. In this paper, the mechanics of these rupture events is described, and the effect of insertion velocity on needle force, tissue deformation, and needle work is analyzed. Using the J integral method from fracture mechanics, rupture events are modeled as sudden crack extensions that occur when the release rate J of strain energy concentrated at the tip of the crack exceeds the fracture toughness of the material. It is shown that increasing the velocity of needle insertion will reduce the force of the rupture event when it increases the energy release rate. A nonlinear viscoelastic Kelvin model is then used to predict the relationship between the deformation of tissue and the rupture force at different velocities. The model predicts that rupture deformation and work asymptotically approach minimum values as needle velocity increases. Consequently, most of the benefit of using a higher needle velocity can be achieved using a finite velocity that is inversely proportional to the relaxation time of the tissue. Experiments confirm the analytical predictions with multilayered porcine cardiac tissue.

  17. Graphene cardboard: From ripples to tunable metamaterial

    Science.gov (United States)

    Koskinen, Pekka

    2014-03-01

    Recently, graphene was introduced with tunable ripple texturing, a nanofabric enabled by graphene's remarkable elastic properties. However, one can further envision sandwiching the ripples, thus constructing composite nanomaterial, graphene cardboard. Here, the basic mechanical properties of such structures are investigated computationally. It turns out that graphene cardboard is highly tunable material, for its elastic figures of merit vary orders of magnitude, with Poisson ratio tunable from 10 to -0.5 as one example. These trends set a foundation to guide the design and usage of metamaterials made of rippled van der Waals solids.

  18. A wide-band dielectric characterization system for liquid materials of interest in biology

    OpenAIRE

    Bramanti, Mauro

    1995-01-01

    In many fields of applied research the interest exhists for wide-band dielectric ,characterization of liquid materials, for example, aqueous solutions of biological materials. For this purpose a particular procedure is here proposed, based on the use of a Vectorial Network Analyzer and a suitably designed cell which contains the material under test. Fundamental features of this method are: dielectric characterization directly in the frequency domain without the use of a Fourier inverse trasfo...

  19. A facile synthesis of C{sub 60}-organosilicon hybrid polymers: Considering their tunable optical properties for spin-on-silicon hardmask materials

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin-Kyu; Dao, Tung Duy; Kim, Ye-Seul; Jeong, Hyun-Dam, E-mail: hdjeong@chonnam.ac.kr

    2016-09-15

    Organic-inorganic hybrid materials with high refractive index have attracted considerable attention for many optoelectronic applications, including spin-on-type hardmask for ArF lithography (193 nm). In this study, we demonstrate the synthesis of a C{sub 60}-embedded organosilicon hybrid polymer, C{sub 60}-embedded poly-xylene-hexamethyltrisiloxane hybrid (C{sub 60}-PXS), of tunable optical properties. C{sub 60} was covalently bonded to the PXS backbone through Pt-catalyzed hydrosilylation, in which the PXS was formed possibly by unexpected transition metal-catalyzed benzylic C−H silylation and oxygenation of the o-xylene. The C{sub 60}-PXS thin films fabricated using a spin-coating method showed much higher refractive index by 5–22% according to the curing temperatures, than the PXS thin films containing no C{sub 60}. In particular, the C{sub 60}-PXS thin film cured at 350 °C showed the refractive index (n) and extinction coefficient (k) at 193 nm to be 1.61 and 0.29 that are very close to the optimum values for the Si-hardmask. This implies the high applicability of the C{sub 60}-embedded organosilicon hybrid polymer, C{sub 60}-PXS, for the spin-on Si-hardmask in ArF lithography. - Highlights: • A facile synthetic route for C{sub 60}-embedded organosilicon hybrid polymer was presented. • The hybrid polymer showed much higher refractive index than the polymer without C{sub 60}. • The hybrid polymer is highly applicable for Si-hardmask in terms of optical properties. • It is believed that the properties of the hybrid polymer can be further optimized.

  20. Chemical analysis and biological testing of materials from the EDS coal liquefaction process: a status report

    Energy Technology Data Exchange (ETDEWEB)

    Later, D.W.; Pelroy, R.A.; Wilson, B.W.

    1984-05-01

    Representative process materials were obtained from the EDS pilot plant for chemical and biological analyses. These materials were characterized for biological activity and chemical composition using a microbial mutagenicity assay and chromatographic and mass spectrometric analytical techniques. The two highest boiling distillation cuts, as well as process solvent (PS) obtained from the bottoms recycle mode operation, were tested for initiation of mouse skin tumorigenicity. All three materials were active; the crude 800/sup 0 +/F cut was substantially more potent than the crude bottoms recycle PS or 750 to 800/sup 0/F distillate cut. Results from chemical analyses showed the EDS materials, in general, to be more highly alkylated and have higher hydroaromatic content than analogous SRC II process materials (no in-line process hydrogenation) used for comparison. In the microbial mutagenicity assays the N-PAC fractions showed greater activity than did the aliphatic hydrocarbon, hydroxy-PAH, or PAH fractions, although mutagenicity was detected in certain PAH fractions by a modified version of the standard microbial mutagenicity assay. Mutagenic activities for the EDS materials were lower, overall, than those for the corresponding materials from the SRC II process. The EDS materials produced under different operational modes had distinguishable differences in both their chemical constituency and biological activity. The primary differences between the EDS materials studied here and their SRC II counterparts used for comparison are most likely attributable to the incorporation of catalytic hydrogenation in the EDS process. 27 references, 28 figures, 27 tables.

  1. Finite element simulation for the mechanical characterization of soft biological materials by atomic force microscopy.

    Science.gov (United States)

    Valero, C; Navarro, B; Navajas, D; García-Aznar, J M

    2016-09-01

    The characterization of the mechanical properties of soft materials has been traditionally performed through uniaxial tensile tests. Nevertheless, this method cannot be applied to certain extremely soft materials, such as biological tissues or cells that cannot be properly subjected to these tests. Alternative non-destructive tests have been designed in recent years to determine the mechanical properties of soft biological tissues. One of these techniques is based on the use of atomic force microscopy (AFM) to perform nanoindentation tests. In this work, we investigated the mechanical response of soft biological materials to nanoindentation with spherical indenters using finite element simulations. We studied the responses of three different material constitutive laws (elastic, isotropic hyperelastic and anisotropic hyperelastic) under the same process and analyzed the differences thereof. Whereas linear elastic and isotropic hyperelastic materials can be studied using an axisymmetric simplification, anisotropic hyperelastic materials require three-dimensional analyses. Moreover, we established the limiting sample size required to determine the mechanical properties of soft materials while avoiding boundary effects. Finally, we compared the results obtained by simulation with an estimate obtained from Hertz theory. Hertz theory does not distinguish between the different material constitutive laws, and thus, we proposed corrections to improve the quantitative measurement of specific material properties by nanoindentation experiments.

  2. Evaluation of geologic materials to limit biological intrusion into low-level radioactive waste disposal sites

    Energy Technology Data Exchange (ETDEWEB)

    Hakonson, T.E.

    1986-02-01

    This report describes the results of a three-year research program to evaluate the performance of selected soil and rock trench cap designs in limiting biological intrusion into simulated waste. The report is divided into three sections including a discussion of background material on biological interactions with waste site trench caps, a presentation of experimental data from field studies conducted at several scales, and a final section on the interpretation and limitations of the data including implications for the user.

  3. Chiral THz metamaterial with tunable optical activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jiangfeng [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John [Los Alamos National Laboratory; Chowdhury, Roy [Los Alamos National Laboratory; Zhao, Rongkuo [IOWA STATE UNIV; Soukoullis, Costas M [IOWA STATE UNIV

    2010-01-01

    Optical activity in chiral metamaterials is demonstrated in simulation and shows actively tunable giant polarization rotation at THz frequencies. Electric current distributions show that pure chirality is achieved by our bi-Iayer chiral metamaterial design. The chirality can be optically controlled by illumination with near-infrared light. Optical activity, occurring in chiral materials such as DNA, sugar and many other bio-molecules, is a phenomenon of great importance to many areas of science including molecular biology, analytical chemistry, optoelectronics and display applications. This phenomenon is well understood at an effective medium level as a magnetic/electric moment excited by the electric/magnetic field of the incident electromagnetic (EM) wave. Usually, natural chiral materials exhibit very weak optical activity e.g. a gyrotropic quartz crystal. The optical activity of chiral metamaterials, however, can be five orders of magnitude stronger. Chiral metamaterials are made of sub-wavelength resonators lacking symmetry planes. The asymmetry allows magnetic moments to be excited by the electric field of the incident EM wave and vice versa. Recently, chiral metamaterials have been demonstrated and lead to prospects in giant optical activity, circular dichroism, negative refraction and reversing the Casmir force. These fascinating optical properties require strong chirality, which may be designed through the microscopic structure of chiral metamaterials. However, these metamaterials have a fixed response function, defined by the geometric structuring, which limits their ability to manipulate EM waves. Active metamaterials realize dynamic control of response functions and have produced many influential applications such as ultra-fast switching devices, frequency and phase modulation and memory devices. Introducing active designs to chiral metamaterials will give additional freedom in controlling the optical activity, and therefore enable dynamic manipulation

  4. Graphene and graphene-like two-denominational materials based fluorescence resonance energy transfer (FRET) assays for biological applications.

    Science.gov (United States)

    Tian, Feng; Lyu, Jing; Shi, Jingyu; Yang, Mo

    2017-03-15

    In the past decades, Förster resonance energy transfer (FRET) has been applied in many biological applications to reveal the biological information at the nanoscale. Recently, graphene and graphene-like two-dimensional (2D) nanomaterials started to be used in FRET assays as donors or acceptors including graphene oxide (GO), graphene quantum dot (GQD), graphitic-carbon nitride nanosheets (g-C3N4) and transition metal dichalcogenides (e.g. MoS2, MnO2, and WS2). Due to the remarkable properties such as large surface to volume ratio, tunable energy band, photoluminescence and excellent biocompatibility, these 2D nanomaterials based FRET assays have shown great potential in various biological applications. This review summarizes the recent development of graphene and graphene-like 2D nanomaterials based FRET assays in applications of biosensing, bioimaging, and drug delivery monitoring.

  5. The Widespread Prevalence and Functional Significance of Silk-Like Structural Proteins in Metazoan Biological Materials

    Science.gov (United States)

    McDougall, Carmel; Woodcroft, Ben J.

    2016-01-01

    In nature, numerous mechanisms have evolved by which organisms fabricate biological structures with an impressive array of physical characteristics. Some examples of metazoan biological materials include the highly elastic byssal threads by which bivalves attach themselves to rocks, biomineralized structures that form the skeletons of various animals, and spider silks that are renowned for their exceptional strength and elasticity. The remarkable properties of silks, which are perhaps the best studied biological materials, are the result of the highly repetitive, modular, and biased amino acid composition of the proteins that compose them. Interestingly, similar levels of modularity/repetitiveness and similar bias in amino acid compositions have been reported in proteins that are components of structural materials in other organisms, however the exact nature and extent of this similarity, and its functional and evolutionary relevance, is unknown. Here, we investigate this similarity and use sequence features common to silks and other known structural proteins to develop a bioinformatics-based method to identify similar proteins from large-scale transcriptome and whole-genome datasets. We show that a large number of proteins identified using this method have roles in biological material formation throughout the animal kingdom. Despite the similarity in sequence characteristics, most of the silk-like structural proteins (SLSPs) identified in this study appear to have evolved independently and are restricted to a particular animal lineage. Although the exact function of many of these SLSPs is unknown, the apparent independent evolution of proteins with similar sequence characteristics in divergent lineages suggests that these features are important for the assembly of biological materials. The identification of these characteristics enable the generation of testable hypotheses regarding the mechanisms by which these proteins assemble and direct the construction of

  6. The Widespread Prevalence and Functional Significance of Silk-Like Structural Proteins in Metazoan Biological Materials.

    Science.gov (United States)

    McDougall, Carmel; Woodcroft, Ben J; Degnan, Bernard M

    2016-01-01

    In nature, numerous mechanisms have evolved by which organisms fabricate biological structures with an impressive array of physical characteristics. Some examples of metazoan biological materials include the highly elastic byssal threads by which bivalves attach themselves to rocks, biomineralized structures that form the skeletons of various animals, and spider silks that are renowned for their exceptional strength and elasticity. The remarkable properties of silks, which are perhaps the best studied biological materials, are the result of the highly repetitive, modular, and biased amino acid composition of the proteins that compose them. Interestingly, similar levels of modularity/repetitiveness and similar bias in amino acid compositions have been reported in proteins that are components of structural materials in other organisms, however the exact nature and extent of this similarity, and its functional and evolutionary relevance, is unknown. Here, we investigate this similarity and use sequence features common to silks and other known structural proteins to develop a bioinformatics-based method to identify similar proteins from large-scale transcriptome and whole-genome datasets. We show that a large number of proteins identified using this method have roles in biological material formation throughout the animal kingdom. Despite the similarity in sequence characteristics, most of the silk-like structural proteins (SLSPs) identified in this study appear to have evolved independently and are restricted to a particular animal lineage. Although the exact function of many of these SLSPs is unknown, the apparent independent evolution of proteins with similar sequence characteristics in divergent lineages suggests that these features are important for the assembly of biological materials. The identification of these characteristics enable the generation of testable hypotheses regarding the mechanisms by which these proteins assemble and direct the construction of

  7. The Widespread Prevalence and Functional Significance of Silk-Like Structural Proteins in Metazoan Biological Materials.

    Directory of Open Access Journals (Sweden)

    Carmel McDougall

    Full Text Available In nature, numerous mechanisms have evolved by which organisms fabricate biological structures with an impressive array of physical characteristics. Some examples of metazoan biological materials include the highly elastic byssal threads by which bivalves attach themselves to rocks, biomineralized structures that form the skeletons of various animals, and spider silks that are renowned for their exceptional strength and elasticity. The remarkable properties of silks, which are perhaps the best studied biological materials, are the result of the highly repetitive, modular, and biased amino acid composition of the proteins that compose them. Interestingly, similar levels of modularity/repetitiveness and similar bias in amino acid compositions have been reported in proteins that are components of structural materials in other organisms, however the exact nature and extent of this similarity, and its functional and evolutionary relevance, is unknown. Here, we investigate this similarity and use sequence features common to silks and other known structural proteins to develop a bioinformatics-based method to identify similar proteins from large-scale transcriptome and whole-genome datasets. We show that a large number of proteins identified using this method have roles in biological material formation throughout the animal kingdom. Despite the similarity in sequence characteristics, most of the silk-like structural proteins (SLSPs identified in this study appear to have evolved independently and are restricted to a particular animal lineage. Although the exact function of many of these SLSPs is unknown, the apparent independent evolution of proteins with similar sequence characteristics in divergent lineages suggests that these features are important for the assembly of biological materials. The identification of these characteristics enable the generation of testable hypotheses regarding the mechanisms by which these proteins assemble and direct the

  8. Evaluation of Botanical Reference Materials for the Determination of Vanadium in Biological Samples

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Damsgaard, Else

    1982-01-01

    Three botanical reference materials prepared by the National Bureau of Standards have been studied by neutron activation analysis to evaluate their suitability with respect to the determination of vanadium in biological samples. Various decomposition methods were applied in connection with chemic....... A reference value of 1.15 mg/kg of this material is recommended, based on results from 3 different methods. All three materials are preferable to SRM 1571 Orchard Leaves, while Bowen's Kale remains the material of choice because of its lower concentration....

  9. Membrane materials for storing biological samples intended for comparative nanotoxicological testing

    Science.gov (United States)

    Metelkin, A.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

    2015-11-01

    The study is aimed at identifying the samples of most promising membrane materials for storing dry specimens of biological fluids (Dried Blood Spots, DBS technology). Existing sampling systems using cellulose fiber filter paper have a number of drawbacks such as uneven distribution of the sample spot, dependence of the spot spreading area on the individual biosample properties, incomplete washing-off of the sample due to partially inconvertible sorption of blood components on cellulose fibers, etc. Samples of membrane materials based on cellulose, polymers and glass fiber with applied biosamples were studied using methods of scanning electron microscopy, FT-IR spectroscopy and surface-wetting measurement. It was discovered that cellulose-based membrane materials sorb components of biological fluids inside their structure, while membranes based on glass fiber display almost no interaction with the samples and biological fluid components dry to films in the membrane pores between the structural fibers. This characteristic, together with the fact that membrane materials based on glass fiber possess sufficient strength, high wetting properties and good storage capacity, attests them as promising material for dry samples of biological fluids storage systems.

  10. ZnO nanocomposites modified by hydrophobic and hydrophilic silanes with dramatically enhanced tunable fluorescence and aqueous ultrastability toward biological imaging applications.

    Science.gov (United States)

    Li, Shuying; Sun, Zongzhao; Li, Rui; Dong, Minmin; Zhang, Liyan; Qi, Wei; Zhang, Xuelin; Wang, Hua

    2015-01-01

    Multicolor ZnO quantum dots (QDs) were synthesized and further modified with hydrophobic hexadecyltrimethoxysilane (HDS) and then hydrophilic aminopropyltriethoxysilane (APS) bilayers, resulting in amine-functionalized ZnO@HDS@APS nanocomposites with tunable fluorescence from blue to green yellow. Systematic investigations verify that the resulting ZnO@HDS@APS could display extremely high stability in aqueous media and unexpectedly, dramatically-enhanced fluorescence intensities, which are about 10-fold higher than those of bare ZnO QDs. The feasibility of the as-prepared ZnO nanocomposites for blood, cell, and tissue imaging was preliminarily demonstrated, promising the wide bio-applications for cell or tissue imaging, proteome analysis, drug delivery, and molecular labeling.

  11. ZnO Nanocomposites Modified by Hydrophobic and Hydrophilic Silanes with Dramatically Enhanced Tunable Fluorescence and Aqueous Ultrastability toward Biological Imaging Applications

    Science.gov (United States)

    Li, Shuying; Sun, Zongzhao; Li, Rui; Dong, Minmin; Zhang, Liyan; Qi, Wei; Zhang, Xuelin; Wang, Hua

    2015-02-01

    Multicolor ZnO quantum dots (QDs) were synthesized and further modified with hydrophobic hexadecyltrimethoxysilane (HDS) and then hydrophilic aminopropyltriethoxysilane (APS) bilayers, resulting in amine-functionalized ZnO@HDS@APS nanocomposites with tunable fluorescence from blue to green yellow. Systematic investigations verify that the resulting ZnO@HDS@APS could display extremely high stability in aqueous media and unexpectedly, dramatically-enhanced fluorescence intensities, which are about 10-fold higher than those of bare ZnO QDs. The feasibility of the as-prepared ZnO nanocomposites for blood, cell, and tissue imaging was preliminarily demonstrated, promising the wide bio-applications for cell or tissue imaging, proteome analysis, drug delivery, and molecular labeling.

  12. Electrically tunable functional nanomaterials for actuation and photonics

    OpenAIRE

    Shao, Li-Hua

    2012-01-01

    Nanomaterials with tunable electronic structure exploit the large specific surface area of metal nanostructures along with the strategy of tuning the surface properties through the controlled introduction of space-charge regions. Then, materials with tunable macroscopic properties can be created. The present thesis work achieved a successful synthesis of metallic and carbon-based tunable nanomaterials and demonstrated novel functional behavior in two fields of application: actuation and photo...

  13. Tunable permeability of magnetic wires at microwaves

    Science.gov (United States)

    Panina, L. V.; Makhnovskiy, D. P.; Morchenko, A. T.; Kostishin, V. G.

    2015-06-01

    This paper presents the analysis into microwave magnetic properties of magnetic microwires and their composites in the context of applications in wireless sensors and tunable microwave materials. It is demonstrated that the intrinsic permeability of wires has a wide frequency dispersion with relatively large values in the GHz band. In the case of a specific magnetic anisotropy this results in a tunable microwave impedance which could be used for distributed wireless sensing networks in functional composites. The other range of applications is related with developing the artificial magnetic dielectrics with large and tunable permeability. The composites with magnetic wires with a circumferential anisotropy have the effective permeability which differs substantially from unity for a relatively low concentration (less than 10%). This can make it possible to design the wire media with a negative and tunable index of refraction utilising natural magnetic properties of wires.

  14. Tunable laser applications

    CERN Document Server

    Duarte, FJ

    2008-01-01

    Introduction F. J. Duarte Spectroscopic Applications of Tunable Optical Parametric Oscillators B. J. Orr, R. T. White, and Y. He Solid-State Dye Lasers Costela, I. García-Moreno, and R. Sastre Tunable Lasers Based on Dye-Doped Polymer Gain Media Incorporating Homogeneous Distributions of Functional Nanoparticles F. J. Duarte and R. O. James Broadly Tunable External-Cavity Semiconductor Lasers F. J. Duarte Tunable Fiber Lasers T. M. Shay and F. J. Duarte Fiber Laser Overview and Medical Applications

  15. Tunable Microwave Filter Design Using Thin-Film Ferroelectric Varactors

    Science.gov (United States)

    Haridasan, Vrinda

    Military, space, and consumer-based communication markets alike are moving towards multi-functional, multi-mode, and portable transceiver units. Ferroelectric-based tunable filter designs in RF front-ends are a relatively new area of research that provides a potential solution to support wideband and compact transceiver units. This work presents design methodologies developed to optimize a tunable filter design for system-level integration, and to improve the performance of a ferroelectric-based tunable bandpass filter. An investigative approach to find the origins of high insertion loss exhibited by these filters is also undertaken. A system-aware design guideline and figure of merit for ferroelectric-based tunable band- pass filters is developed. The guideline does not constrain the filter bandwidth as long as it falls within the range of the analog bandwidth of a system's analog to digital converter. A figure of merit (FOM) that optimizes filter design for a specific application is presented. It considers the worst-case filter performance parameters and a tuning sensitivity term that captures the relation between frequency tunability and the underlying material tunability. A non-tunable parasitic fringe capacitance associated with ferroelectric-based planar capacitors is confirmed by simulated and measured results. The fringe capacitance is an appreciable proportion of the tunable capacitance at frequencies of X-band and higher. As ferroelectric-based tunable capac- itors form tunable resonators in the filter design, a proportionally higher fringe capacitance reduces the capacitance tunability which in turn reduces the frequency tunability of the filter. Methods to reduce the fringe capacitance can thus increase frequency tunability or indirectly reduce the filter insertion-loss by trading off the increased tunability achieved to lower loss. A new two-pole tunable filter topology with high frequency tunability (> 30%), steep filter skirts, wide stopband

  16. Neutron-Activation Analysis of Biological Material with High Radiation Levels

    Energy Technology Data Exchange (ETDEWEB)

    Samsahl, K.

    1966-09-15

    A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min.

  17. Measuring the complex permittivity tensor of uniaxial biological materials with coplanar waveguide transmission line

    Science.gov (United States)

    A simple and accurate technique is described for measuring the uniaxial permittivity tensor of biological materials with a coplanar waveguide transmission-line configuration. Permittivity tensor results are presented for several chicken and beef fresh meat samples at 2.45 GHz....

  18. Occupational accidents with exposure to biological material: Description of cases in Bahia

    Directory of Open Access Journals (Sweden)

    Técia Maria Santos Carneiro e Cordeiro

    2016-04-01

    Full Text Available Background and Objective: This study is included in the field of public health in Brazil, in particular occupational health, by the occupational accidents with exposure to biological material consists of a preventable injury. Thus, the objective was to describe risk factors the of occupational accidents with exposure to biological material and the conduct postexposure adopted notified of cases in Notifiable Diseases Information System (SINAN in the State of Bahia in 2012. Methods: This is a descriptive epidemiological study realized with data from the injuries of notifications SINAN in February 2013, the analysis was realized using descriptive statistics in absolute frequencies and relative. Results: The results indicate a higher occurrence of occupational accidents involving exposure to biological materials in Bahia in the female population (78.1% and aged between 30-49 years (51.5%; the blood was fluid larger contact in accidents 75.2% by percutaneous (71.5%; post-exposure procedures were adopted in accordance recommended by the Ministry of Health; divers information were not fulfilled in the notifications and only 23.8% of Occupational Accidents Comunication (CAT were issued. Conclusion: It is considered necessary to draw up strategies on occupational health and safety, consciousness of workers about the relevance of the measures adopted after occupational accidents with exposure to biological material and the training of professionals for case notification and research to fill all the fields of the notification form and also the issuance of CAT.

  19. Simultaneous Determination of Arsenic, Manganese, and Selenium in Biological Materials by Neutron-Activation Analysis

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Damsgaard, Else

    1973-01-01

    A new method was developed for the simultaneous determination of arsenic, manganese, and selenium in biological material by thermal-neutron activation analysis. The use of 81 mSe as indicator for selenium permitted a reduction of activation time to 1 hr for a 1 g sample, and the possibility of loss...

  20. New materials and biologically active preparations on the basis of (organilthio) chloroacetylene

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ (Organylthio)chloroacetylenes [RSC≡CCl, 1], the object of our systematic research, provide a promising source of new classes of polyfunctional compounds of acetylenic and polyheterocyclic seriesamong which biologically active substances, monomers and precursors for the preparation of new materials possessing a whole complex of valuable properties have been recognized.

  1. New materials and biologically active preparations on the basis of (organilthio) chloroacetylene

    Institute of Scientific and Technical Information of China (English)

    D'yachkova; S.; G.

    2005-01-01

    (Organylthio)chloroacetylenes [RSC≡CCl, 1], the object of our systematic research, provide a promising source of new classes of polyfunctional compounds of acetylenic and polyheterocyclic seriesamong which biologically active substances, monomers and precursors for the preparation of new materials possessing a whole complex of valuable properties have been recognized.……

  2. Differential Multiscale Modeling of Chemically Complex Materials under Heavy Deformation: Biological, Bioinspired and Synthetic Hierarchical Materials

    Science.gov (United States)

    2010-06-01

    of Computational and Theoretical Nanoscience, Vol. 7, pp. 354-359, 2010. M.J. Buehler, Y.C. Yung, “How protein materials balance strength, robustness...toughness to surface cracks while minimize their plastic deformation in the interior of the materia . 19 Preliminary results of the laminated 2-hierarchy

  3. Environmental impacts of post-consumer material managements: recycling, biological treatments, incineration.

    Science.gov (United States)

    Valerio, F

    2010-11-01

    The environmental impacts of recycling, mechanical biological treatments (MBT) and waste-to-energy incineration, the main management strategies to respond to the increasing production of post-consumer materials are reviewed and compared. Several studies carried out according to life-cycle assessment (LCA) confirm that the lowest environmental impact, on a global scale, is obtained by recycling and by biological treatments (composting and anaerobic fermentations) if compost is used in agriculture. The available air emission factors suggest that, on a local scale, mechanical biological treatments with energy recovery of biogas, may be intrinsically safer than waste-to-energy incinerators. Several studies confirm the capability of biological treatments to degrade many toxic xenobiotic contaminating urban wastes such as dioxins and polycyclic aromatic hydrocarbons, an important property to be improved, for safe agricultural use of compost. Further LCA studies to compare the environmental impact of MBTs and of waste-to-energy incinerators are recommended.

  4. Immobilized Biofilm in Thermophilic Biohydrogen Production using Synthetic versus Biological Materials

    Directory of Open Access Journals (Sweden)

    Jaruwan Wongthanate

    2015-02-01

    Full Text Available Biohydrogen production was studied from the vermicelli processing wastewater using synthetic and biological materials as immobilizing substrate employing a mixed culture in a batch reactor operated at the initial pH 6.0 and thermophilic condition (55 ± 1ºC. Maximum cumulative hydrogen production (1,210 mL H2/L wastewater was observed at 5% (v/v addition of ring-shaped synthetic material, which was the ring-shaped hydrophobic acrylic. Regarding 5% (v/v addition of synthetic and biological materials, the maximum cumulative hydrogen production using immobilizing synthetic material of ball-shaped hydrophobic polyethylene (HBPE (1,256.5 mL H2/L wastewater was a two-fold increase of cumulative hydrogen production when compared to its production using immobilizing biological material of rope-shaped hydrophilic ramie (609.8 mL H2/L wastewater. SEM observation of immobilized biofilm on a ball-shaped HBPE or a rope-shaped hydrophilic ramie was the rod shape and gathered into group.

  5. HRI catalytic two-stage liquefaction (CTSL) process materials: chemical analysis and biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.W.; Later, D.W.

    1985-12-01

    This report presents data from the chemical analysis and biological testing of coal liquefaction materials obtained from the Hydrocarbon Research, Incorporated (HRI) catalytic two-stage liquefaction (CTSL) process. Materials from both an experimental run and a 25-day demonstration run were analyzed. Chemical methods of analysis included adsorption column chromatography, high-resolution gas chromatography, gas chromatography/mass spectrometry, low-voltage probe-inlet mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The biological activity was evaluated using the standard microbial mutagenicity assay and an initiation/promotion assay for mouse-skin tumorigenicity. Where applicable, the results obtained from the analyses of the CTSL materials have been compared to those obtained from the integrated and nonintegrated two-stage coal liquefaction processes. 18 refs., 26 figs., 22 tabs.

  6. Thermo-fluidic devices and materials inspired from mass and energy transport phenomena in biological system

    Institute of Scientific and Technical Information of China (English)

    Jian XIAO; Jing LIU

    2009-01-01

    Mass and energy transport consists of one of the most significant physiological processes in nature, which guarantees many amazing biological phenomena and activ-ities. Borrowing such idea, many state-of-the-art thermo-fluidic devices and materials such as artificial kidneys, carrier erythrocyte, blood substitutes and so on have been successfully invented. Besides, new emerging technologies are still being developed. This paper is dedicated to present-ing a relatively complete review of the typical devices and materials in clinical use inspired by biological mass and energy transport mechanisms. Particularly, these artificial thermo-fluidic devices and materials will be categorized into organ transplantation, drug delivery, nutrient transport, micro operation, and power supply. Potential approaches for innovating conventional technologies were discussed, corresponding biological phenomena and physical mechan-isms were interpreted, future promising mass-and-energy-transport-based bionic devices were suggested, and prospects along this direction were pointed out. It is expected that many artificial devices based on biological mass and energy transport principle will appear to better improve vari-ous fields related to human life in the near future.

  7. MEMS Tunable Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2014-01-01

    Addressing low frequency bands is challenging on small platforms. Tunability is a promising solution to cover the bandwidth required for 4G mobile communication. The work presents two designs and shows that for comparable efficiency and bandwidth, the tunable antenna occupies half the volume...... required by the wide-band antenna....

  8. Searching for biological traces on different materials using a forensic light source and infrared photography.

    Science.gov (United States)

    Sterzik, V; Panzer, S; Apfelbacher, M; Bohnert, M

    2016-05-01

    Because biological traces often play an important role in the investigation process of criminal acts, their detection is essential. As they are not always visible to the human eye, tools like a forensic light source or infrared photography can be used. The intention of the study presented was to give advice how to visualize biological traces best. Which wavelengths and/or filters give the best results for different traces on different fabrics of different colors? Therefore, blood (undiluted and diluted), semen, urine, saliva, and perspiration have been examined on 29 different materials.

  9. Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Kuznetsova, Svetlana M.; Zhukovsky, Sergei

    2015-01-01

    We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric...

  10. Novel microwave near-field sensors for material characterization, biology, and nanotechnology

    CERN Document Server

    Joffe, R; Shavit, R

    2015-01-01

    The wide range of interesting electromagnetic behavior of contemporary materials requires that experimentalists working in this field master many diverse measurement techniques and have a broad understanding of condensed matter physics and biophysics. Measurement of the electromagnetic response of materials at microwave frequencies is important for both fundamental and practical reasons. In this paper, we propose a novel near-field microwave sensor with application to material characterization, biology, and nanotechnology. The sensor is based on a subwavelength ferrite-disk resonator with magnetic-dipolar-mode (MDM) oscillations. Strong energy concentration and unique topological structures of the near fields originated from the MDM resonators allow effective measuring material parameters in microwaves, both for ordinary structures and objects with chiral properties.

  11. Dielectric relaxation time and structure of bound water in biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Mashimo, S.; Kuwabara, S.; Yagihara, S.; Higasi, K.

    1987-12-03

    The dielectric behavior of living tissues and a number of biological materials was examined by new equipment of the time domain reflectometry method in a wide frequency range of 10/sup 7/-10/sup 10/ Hz. The authors found two peaks of Debye absorption around 100 MHz and 20 GHz for all the materials. The low-frequency absorption is probably due to bound water while the high-frequency absorption to free water. From the observed relaxation times of bound water a hypothesis is ventured on the structure of bound water and its relaxation mechanism.

  12. Determination of cobalt and nickel in biological materials using catalytic adsorptive stripping voltammetry

    OpenAIRE

    Bobrowski, Andrzej; Zarębski, Jerzy; Królicka, Agnieszka

    2012-01-01

    The paper discusses the utilisation of the catalytic adsorptive stripping voltammetric method for the simultaneous determination of Co and Ni in biological materials such as hair, oyster tissue, bovine liver and oriental tobacco leaves. For this purpose the most sensitive and selective catalytic-adsorptive system with nioxime and nitrite has been selected. The optimal parameters, including concentration of the supporting electrolyte, pH and accumulation time and potential, have be...

  13. Development and Applications Of Photosensitive Device Systems To Studies Of Biological And Organic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, Sol

    2012-01-20

    The primary focus of the grant is the development of new x-ray detectors for biological and materials work at synchrotron sources, especially Pixel Array Detectors (PADs), and the training of students via research applications to problems in biophysics and materials science using novel x-ray methods. This Final Progress Report provides a high-level overview of the most important accomplishments. These major areas of accomplishment include: (1) Development and application of x-ray Pixel Array Detectors; (2) Development and application of methods of high pressure x-ray crystallography as applied to proteins; (3) Studies on the synthesis and structure of novel mesophase materials derived from block co-polymers.

  14. Durability of the tunable adhesive superhydrophobic PTFE surfaces for harsh environment applications

    Science.gov (United States)

    Fang, Yao; Yong, Jiale; Chen, Feng; Huo, Jinglan; Yang, Qing; Bian, Hao; Du, Guangqing; Hou, Xun

    2016-09-01

    Tunable adhesive superhydrophobic materials have attracted increasing research interest due to their applications in microdroplet manipulation, biological detection and microfluidic system. However, most of the artificial materials easily lose superhydrophobicity in harsh environments. The durability of superhydrophobic materials is very important to extend their lifetime in practical applications. In this paper, bioinspired durable superhydrophobicity with tunable adhesion on polytetrafluoroethylene surfaces is realized via a one-step femtosecond laser irradiation. On the laser-induced superhydrophobic surfaces, the sliding angle can be tuned from 1° to 90° (water droplet is pinned on the surface at any titled angles). The tunable water adhesion results from different contact states which change from the lotus state to the transition state and then to the composite state with increasing average distance of irradiation points. Water droplet quick localization and no-loss droplet transportation were achieved through designing surface adhesion. In addition, the resultant surfaces are so stable that they can maintain superhydrophobicity even after storing in harsh environments, without dramatical superhydrophobicity decay for a long time.

  15. Enhanced Removal of Lead by Chemically and Biologically Treated Carbonaceous Materials

    Directory of Open Access Journals (Sweden)

    Mohamed E. Mahmoud

    2012-01-01

    Full Text Available Hybrid sorbents and biosorbents were synthesized via chemical and biological treatment of active carbon by simple and direct redox reaction followed by surface loading of baker’s yeast. Surface functionality and morphology of chemically and biologically modified sorbents and biosorbents were studied by Fourier Transform Infrared analysis and scanning electron microscope imaging. Hybrid carbonaceous sorbents and biosorbents were characterized by excellent efficiency and superiority toward lead(II sorption compared to blank active carbon providing a maximum sorption capacity of lead(II ion as 500 μmol g−1. Sorption processes of lead(II by these hybrid materials were investigated under the influence of several controlling parameters such as pH, contact time, mass of sorbent and biosorbent, lead(II concentration, and foreign ions. Lead(II sorption mechanisms were found to obey the Langmuir and BET isotherm models. The potential applications of chemically and biologically modified-active carbonaceous materials for removal and extraction of lead from real water matrices were also studied via a double-stage microcolumn technique. The results of this study were found to denote to superior recovery values of lead (95.0–99.0±3.0–5.0% by various carbonaceous-modified-bakers yeast biosorbents.

  16. Marketing the use of the space environment for the processing of biological and pharmaceutical materials

    Science.gov (United States)

    1984-01-01

    The perceptions of U.S. biotechnology and pharmaceutical companies concerning the potential use of the space environment for the processing of biological substances was examined. Physical phenomena that may be important in space-base processing of biological materials are identified and discussed in the context of past and current experiment programs. The capabilities of NASA to support future research and development, and to engage in cooperative risk sharing programs with industry are discussed. Meetings were held with several biotechnology and pharmaceutical companies to provide data for an analysis of the attitudes and perceptions of these industries toward the use of the space environment. Recommendations are made for actions that might be taken by NASA to facilitate the marketing of the use of the space environment, and in particular the Space Shuttle, to the biotechnology and pharmaceutical industries.

  17. Development of Standards for NanoSIMS Analyses of Biological Materials

    Energy Technology Data Exchange (ETDEWEB)

    Davission, M L; Weber, P K; Pett-Ridge, J; Singer, S

    2008-07-31

    NanoSIMS is a powerful analytical technique for investigating element distributions at the nanometer scale, but quantifying elemental abundances requires appropriate standards, which are not readily available for biological materials. Standards for trace element analyses have been extensively developed for secondary ion mass spectrometry (SIMS) in the semiconductor industry and in the geological sciences. The three primary approaches for generating standards for SIMS are: (1) ion implantation (2) using previously characterized natural materials, and (3) preparing synthetic substances. Ion implantation is a reliable method for generating trace element standards, but it is expensive, which limits investigation of the analytical issues discussed above. It also requires low background levels of the elements of interest. Finding or making standard materials has the potential to provide more flexibility than ion implantation, but realizing homogeneity at the nano-scale is in itself a significant challenge. In this study, we experiment with all three approaches, but with an emphasis toward synthetic organic polymers in order to reduce costs, increase flexibility, and achieve a wide dynamic concentration range. This emphasis serves to meet the major challenge for biological samples of identifying matrix matched, homogeneous material. Biological samples themselves are typically heterogeneous at the scale of microns to 100s of microns, and therefore they are poor SIMS standards. Therefore, we focused on identifying 'biological-like' materials--either natural or synthetic--that can be used for standards. The primary criterion is that the material be as compositionally similar to biological samples as possible (primarily C, H, O, and N). For natural material we adsorbed organic colloids consisting of peptidoglycan (i.e., amino sugars), activated charcoal, and humic acids. Experiments conducted with Si on peptidoglycan showed low affinity as SiO{sub 2}, yet its

  18. Biological and Biomimetic Low-Temperature Routes to Materials for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Daniel E. [Univ. of California, Santa Barbara, CA (United States). Inst. for Collaborative Biotechnologies

    2016-08-29

    New materials are needed to significantly improve the efficiencies of energy harnessing, transduction and storage, yet the synthesis of advanced composites and multi-metallic semiconductors with nanostructures optimized for these functions remains poorly understood and even less well controlled. To help address this need, we proposed three goals: (1) to further investigate the hierarchical structure of the biologically synthesized silica comprising the skeletal spicules of sponges that we discovered, to better resolve the role and mechanism of templating by the hierarchically assembled silicatein protein filament; (2) to extend our molecular and genetic analyses and engineering of silicatein, the self-assembling, structure-directing, silica-synthesizing enzyme we discovered and characterized, to better understand and manipulate the catalysis and templating of semiconductor synthesis,; and (3) to further investigate, scale up and harness the biologically inspired, low-temperature, kinetically controlled catalytic synthesis method we developed (based on the mechanism we discovered in silicatein) to investigate the kinetic control of the structure-function relationships in magnetic materials, and develop new materials for energy applications. The bio-inspired catalytic synthesis method we have developed is low-cost, low temperature, and operates without the use of polluting chemicals. In addition to direct applications for improvement of batteries and fuel cells, the broader impact of this research includes a deeper fundamental understanding of the factors governing kinetically controlled synthesis and its control of the emergent nanostructure and performance of a wide range of nanomaterials for energy applications.

  19. Tunable permeability of magnetic wires at microwaves

    Energy Technology Data Exchange (ETDEWEB)

    Panina, L.V., E-mail: lpanina@plymouth.ac.uk [National University of Science and Technology, MISiS, Moscow (Russian Federation); Institute for Design Problems in Microelectronics, RAN, Moscow (Russian Federation); Makhnovskiy, D.P. [School of Computing and Mathematics, University of Plymouth (United Kingdom); Morchenko, A.T.; Kostishin, V.G. [National University of Science and Technology, MISiS, Moscow (Russian Federation)

    2015-06-01

    This paper presents the analysis into microwave magnetic properties of magnetic microwires and their composites in the context of applications in wireless sensors and tunable microwave materials. It is demonstrated that the intrinsic permeability of wires has a wide frequency dispersion with relatively large values in the GHz band. In the case of a specific magnetic anisotropy this results in a tunable microwave impedance which could be used for distributed wireless sensing networks in functional composites. The other range of applications is related with developing the artificial magnetic dielectrics with large and tunable permeability. The composites with magnetic wires with a circumferential anisotropy have the effective permeability which differs substantially from unity for a relatively low concentration (less than 10%). This can make it possible to design the wire media with a negative and tunable index of refraction utilising natural magnetic properties of wires. - Highlights: • Applications of magnetic microwires for functional composites and distributed sensor networks are proposed. • Diluted composites with magnetic microwires can demonstrate tunable left-handed properties. • Large microwave permeability combined with a specific magnetic structure lead to a large and sensitive microwave magnetoimpedance. • Microwave magnetoimpedance highly sensitive to temperature is demonstrated.

  20. Perovskite Superlattices as Tunable Microwave Devices

    Science.gov (United States)

    Christen, H. M.; Harshavardhan, K. S.

    2003-01-01

    Experiments have shown that superlattices that comprise alternating epitaxial layers of dissimilar paraelectric perovskites can exhibit large changes in permittivity with the application of electric fields. The superlattices are potentially useful as electrically tunable dielectric components of such microwave devices as filters and phase shifters. The present superlattice approach differs fundamentally from the prior use of homogeneous, isotropic mixtures of base materials and dopants. A superlattice can comprise layers of two or more perovskites in any suitable sequence (e.g., ABAB..., ABCDABCD..., ABACABACA...). Even though a single layer of one of the perovskites by itself is not tunable, the compositions and sequence of the layers can be chosen so that (1) the superlattice exhibits low microwave loss and (2) the interfacial interaction between at least two of the perovskites in the superlattice renders either the entire superlattice or else at least one of the perovskites tunable.

  1. A bio-inspired approach for in situ synthesis of tunable adhesive.

    Science.gov (United States)

    Sun, Leming; Yi, Sijia; Wang, Yongzhong; Pan, Kang; Zhong, Qixin; Zhang, Mingjun

    2014-03-01

    Inspired by the strong adhesive produced by English ivy, this paper proposes an in situ synthesis approach for fabricating tunable nanoparticle enhanced adhesives. Special attention was given to tunable features of the adhesive produced by the biological process. Parameters that may be used to tune properties of the adhesive will be proposed. To illustrate and validate the proposed approach, an experimental platform was presented for fabricating tunable chitosan adhesive enhanced by Au nanoparticles synthesized in situ. This study contributes to a bio-inspired approach for in situ synthesis of tunable nanocomposite adhesives by mimicking the natural biological processes of ivy adhesive synthesis.

  2. Analytical methods for determination of terbinafine hydrochloride in pharmaceuticals and biological materials$

    Institute of Scientific and Technical Information of China (English)

    Basavaiah Kanakapura n; Vamsi Krishna Penmatsa

    2016-01-01

    Terbinafine is a new powerful antifungal agent indicated for both oral and topical treatment of myco-sessince. It is highly effective in the treatment of determatomycoses. The chemical and pharmaceutical analysis of the drug requires effective analytical methods for quality control and pharmacodynamic and pharmacokinetic studies. Ever since it was introduced as an effective antifungal agent, many methods have been developed and validated for its assay in pharmaceuticals and biological materials. This article reviews the various methods reported during the last 25 years.

  3. Continuously tunable optical multidimensional Fourier-transform spectrometer.

    Science.gov (United States)

    Dey, P; Paul, J; Bylsma, J; Deminico, S; Karaiskaj, D

    2013-02-01

    A multidimensional optical nonlinear spectrometer (MONSTR) is a robust, ultrastable platform consisting of nested and folded Michelson interferometers that can be actively phase stabilized. The MONSTR provides output pulses for nonlinear excitation of materials and phase-stabilized reference pulses for heterodyne detection of the induced signal. This platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delays between them while maintaining phase stability. This arrangement is ideal for performing coherent optical experiments, such as multidimensional Fourier-transform spectroscopy. The present work reports on overcoming some important limitations on the original design of the MONSTR apparatus. One important advantage of the MONSTR is the fact that it is a closed platform, which provides the high stability. Once the optical alignment is performed, it is desirable to maintain the alignment over long periods of time. The previous design of the MONSTR was limited to a narrow spectral range defined by the optical coating of the beam splitters. In order to achieve tunability over a broad spectral range the internal optics needed to be changed. By using broadband coated and wedged beam splitters and compensator plates, combined with modifications of the beam paths, continuous tunability can be achieved from 520 nm to 1100 nm without changing any optics or performing alignment of the internal components of the MONSTR. Furthermore, in order to achieve continuous tunability in the spectral region between 520 nm and 720 nm, crucially important for studies on numerous biological molecules, a single longitudinal mode laser at 488.5 nm was identified and used as a metrology laser. The shorter wavelength of the metrology laser as compared to the usual HeNe laser has also increased the phase stability of the system. Finally, in order to perform experiments in the reflection geometry, a simple method to achieve active phase stabilization

  4. Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine

    Science.gov (United States)

    Rodríguez-Fernández, Luis

    2010-09-01

    Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

  5. QEEN Workshop: "Quantifying Exposure to Engineered Nano-materials from Manufactured Products": Write Up Biological Tissues and Media

    Science.gov (United States)

    The measurement and characterization of nanomaterials in biological tissues is complicated by a number of factors including: the sensitivity of the assay to small sized particles or low concentrations of materials; the ability to distinguish different forms and transformations of...

  6. Freely-tunable broadband polarization rotator for terahertz waves

    Science.gov (United States)

    Peng, Ru-Wen; Fan, Ren-Hao; Zhou, Yu; Jiang, Shang-Chi; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    It is known that commercially-available terahertz (THz) emitters usually generate linearly polarized waves only along certain directions, but in practice, a polarization rotator that is capable of rotating the polarization of THz waves to any direction is particularly desirable and it will have various important applications. In this work, we demonstrate a freely tunable polarization rotator for broadband THz waves using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized THz wave to any desired direction with nearly perfect conversion efficiency. The device performance has been experimentally demonstrated by both THz transmission spectra and direct imaging. The polarization rotation originates from multi wave interference in the three-layer grating structure based on the scattering-matrix analysis. We can expect that this active broadband polarization rotator has wide applications in analytical chemistry, biology, communication technology, imaging, etc.. Reference: R. H. Fan, Y. Zhou, X. P. Ren, R. W. Peng, S. C. Jiang, D. H. Xu, X. Xiong, X. R. Huang, and Mu Wang, Advanced Materials 27,1201(2015). Freely-tunable broadband polarization rotator for terahertz waves.

  7. Occupational exposure to potentially infectious biological material in a dental teaching environment.

    Science.gov (United States)

    Machado-Carvalhais, Helenaura P; Ramos-Jorge, Maria L; Auad, Sheyla M; Martins, Laura H P M; Paiva, Saul M; Pordeus, Isabela A

    2008-10-01

    The aims of this cross-sectional study were to determine the prevalence of occupational accidents with exposure to biological material among undergraduate students of dentistry and to estimate potential risk factors associated with exposure to blood. Data were collected through a self-administered questionnaire (86.4 percent return rate), which was completed by a sample of 286 undergraduate dental students (mean age 22.4 +/-2.4 years). The students were enrolled in the clinical component of the curriculum, which corresponds to the final six semesters of study. Descriptive, bivariate, simple logistic regression and multiple logistic regression (Forward Stepwise Procedure) analyses were performed. The level of statistical significance was set at 5 percent. Percutaneous and mucous exposures to potentially infectious biological material were reported by 102 individuals (35.6 percent); 26.8 percent reported the occurrence of multiple episodes of exposure. The logistic regression analyses revealed that the incomplete use of individual protection equipment (OR=3.7; 95 percent CI 1.5-9.3), disciplines where surgical procedures are carried out (OR=16.3; 95 percent CI 7.1-37.2), and handling sharp instruments (OR=4.4; 95 percent CI 2.1-9.1), more specifically, hollow-bore needles (OR=6.8; 95 percent CI 2.1-19.0), were independently associated with exposure to blood. Policies of reviewing the procedures during clinical practice are recommended in order to reduce occupational exposure.

  8. Biologic

    CERN Document Server

    Kauffman, L H

    2002-01-01

    In this paper we explore the boundary between biology and the study of formal systems (logic). In the end, we arrive at a summary formalism, a chapter in "boundary mathematics" where there are not only containers but also extainers ><, entities open to interaction and distinguishing the space that they are not. The boundary algebra of containers and extainers is to biologic what boolean algebra is to classical logic. We show how this formalism encompasses significant parts of the logic of DNA replication, the Dirac formalism for quantum mechanics, formalisms for protein folding and the basic structure of the Temperley Lieb algebra at the foundations of topological invariants of knots and links.

  9. Evaluation of flow injection analysis for determination of cholinesterase activities in biological material.

    Science.gov (United States)

    Cabal, Jiri; Bajgar, Jiri; Kassa, Jiri

    2010-09-06

    The method for automatic continual monitoring of acetylcholinesterase (AChE) activity in biological material is described. It is based on flexible system of plastic pipes mixing samples of biological material with reagents for enzyme determination; reaction product penetrates through the semipermeable membrane and it is spectrophotometrically determined (Ellman's method). It consists of sampling (either in vitro or in vivo), adding the substrate and flowing to dialyzer; reaction product (thiocholine) is dialyzed and mixed with 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB) transported to flow spectrophotometer. Flowing of all materials is realised using peristaltic pump. The method was validated: time for optimal hydratation of the cellophane membrane; type of the membrane; type of dialyzer; conditions for optimal permeation of reaction components; optimization of substrate and DTNB concentrations (linear dependence); efficacy of peristaltic pump; calibration of analytes after permeation through the membrane; excluding of the blood permeation through the membrane. Some examples of the evaluation of the effects of AChE inhibitors are described. It was demonstrated very good uniformity of peaks representing the enzyme activity (good reproducibility); time dependence of AChE inhibition caused by VX in vitro in the rat blood allowing to determine the half life of inhibition and thus, bimolecular rate constants of inhibition; reactivation of inhibited AChE by some reactivators, and continual monitoring of the activity in the whole blood in vivo in intact and VX-intoxicated rats. The method is simple and not expensive, allowing automatic determination of AChE activity in discrete or continual samples in vitro or in vivo. It will be evaluated for further research of cholinesterase inhibitors.

  10. Tunable Microfluidic Dye Laser

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Helbo, Bjarne; Kutter, Jörg Peter

    2003-01-01

    We present a tunable microfluidic dye laser fabricated in SU-8. The tunability is enabled by integrating a microfluidic diffusion mixer with an existing microfluidic dye laser design by Helbo et al. By controlling the relative flows in the mixer between a dye solution and a solvent......, the concentration of dye in the laser cavity can be adjusted, allowing the wavelength to be tuned. Wavelength tuning controlled by the dye concentration was demonstrated with macroscopic dye lasers already in 1971, but this principle only becomes practically applicable by the use of microfluidic mixing...

  11. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul

    2005-06-28

    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  12. Occupational exposure to contaminated biological material: perceptions and feelings experienced among dental students

    Directory of Open Access Journals (Sweden)

    Camila PINELLI

    Full Text Available INTRODUCTION: Dental students may be a particularly vulnerable group exposed to the risk of acquiring infections through occupational injuries.OBJECTIVE: To investigate the perceptions with regard to their occupational exposure to potentially infectious biologic materials.MATERIAL AND METHOD: Interviews were conducted by means of a script with open questions. The speeches were recorded, transcribed and qualitative analysis was performed with the aid of QUALIQUANTISOFT® software. The Collective Subject Discourse (CSD was obtained.RESULT: The feeling most frequently experienced was related to the fear of contagion. Most accidents occurred during the handling of sharp dental instruments. Respondents attributed the occurrence of accidents especially the lack of attention, carelessness while handling sharp instruments, and lack of use of Personal Protective Equipment. As regards the measures taken right after the exposure, they "washed the local area". Other respondents reported they "continued the dental treatment". They complained mostly about the fear of having been infected, and because they had to leave the faculty to take blood exams for HIV screening. As part of the learning experience the injured reported they paid more attention when handling sharp instruments. The students informed that any type of injury due to contact with contaminated material must be notified. However, they were neglectful about reporting their own injury.CONCLUSION: Education strategies for preventive measures related to occupational exposure must be restructured, because the knowledge and the fear of contagion among dental students were not always sufficient for a complete adherence to treatment protocols and notification.

  13. Tunable Microwave Component Technologies for SatCom-Platforms

    Science.gov (United States)

    Maune, Holger; Jost, Matthias; Wiens, Alex; Weickhmann, Christian; Reese, Roland; Nikfalazar, Mohammad; Schuster, Christian; Franke, Tobias; Hu, Wenjuan; Nickel, Matthias; Kienemund, Daniel; Prasetiadi, Ananto Eka; Jakoby, Rolf

    2017-03-01

    Modern communication platforms require a huge amount of switched RF component banks especially made of different filters and antennas to cover all operating frequencies and bandwidth for the targeted services and application scenarios. In contrast, reconfigurable devices made of tunable components lead to a considerable reduction in complexity, size, weight, power consumption, and cost. This paper gives an overview of suitable technologies for tunable microwave components especially for SatCom applications. Special attention is given to tunable components based on functional materials such as barium strontium titanate (BST) and liquid crystal (LC).

  14. Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hongli; Luo, Wei; Ciesielski, Peter N.; Fang, Zhiqiang; Zhu, J. Y.; Henriksson, Gunnar; Himmel, Michael E.; Hu, Liangbing

    2016-08-24

    goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure-properties-application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.

  15. Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications.

    Science.gov (United States)

    Zhu, Hongli; Luo, Wei; Ciesielski, Peter N; Fang, Zhiqiang; Zhu, J Y; Henriksson, Gunnar; Himmel, Michael E; Hu, Liangbing

    2016-08-24

    goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure-properties-application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.

  16. Tunability enhanced electromagnetic wiggler

    Science.gov (United States)

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  17. A rapid screening method for heavy metals in biological materials by emission spectroscopy.

    Science.gov (United States)

    Blacklock, E C; Sadler, P A

    1981-06-02

    A semi-quantitative screening method for heavy metals in biological material is described. The metals are complexed with ammonium pyrrolidine dithiocarbamate, sodium diethyl dithiocarbamate and potassium sodium tartrate. The solutions are adjusted to pH 4 and then extracted into chloroform. The chloroform phase is evaporated onto a matrix mixture of lithium fluoride and graphite. The sample is analysed by direct current arc emission spectroscopy using a 3 metre grating spectrograph. The spectra are recorded on a photographic plate. The method is developed on aqueous and spiked samples and then applied to in vivo samples containing toxic levels of heavy metals. Atomic absorption spectroscopy is used to check standard concentrations and to monitor the efficiency of the extraction procedure.

  18. Why should we respect the privacy of donors of biological material?

    Science.gov (United States)

    Tännsjö, Torbjörn

    2011-02-01

    Why should we respect the privacy of donors of biological material? The question is answered in the present article in general philosophical terms from the point of view of an ethics of honour, a libertarian theory of rights, a view of respect for privacy based on the idea that autonomy is of value in itself, and utilitarianism respectively. For different reasons the ethics of honour and the idea of the value of autonomy are set to one side. It surfaces that the moral rights theory and utilitarianism present conflicting answers to the question. The main thrust of the argument is that there is no way of finding an overlapping consensus, so politicians have to take decisions that are bound to be controversial in that they can be questioned on reasonable philosophical grounds.

  19. A controlled rate freeze/thaw system for cryopreservation of biological materials

    Science.gov (United States)

    Anselmo, V. J.; Harrison, R. G.

    1979-01-01

    A system which allows programmable temperature-time control for a 5 cc sample volume of an arbitrary biological material was constructed. Steady state and dynamic temperature control was obtained by supplying heat to the sample volume through resistive elements constructed as an integral part of the sample container. For cooling purposes, this container was totally immersed into a cold heat sink. Sample volume thermodynamic property data were obtained by measurements of heater power and heat flux through the container walls. Using a mixture of dry ice and alcohol at -79 C, sample volume was controlled from +40 C to -60 C at rates from steady state to + or - 65 C/min. Steady state temperature precision was better than 0.2 C while the dynamic capability depends on the temperature rate of change as well as the thermal mass of the sample and the container.

  20. Magnetic field tunable capacitive dielectric:ionic-liquid sandwich composites

    Science.gov (United States)

    Wu, Ye; Bhalla, Amar; Guo, Ruyan

    2016-03-01

    We examined the tunability of the capacitance for GaFeO3-ionic liquid-GaFeO3 composite material by external magnetic and electric field. Up to 1.6 folds of capacitance tunability could be achieved at 957 kHz with voltage 4 V and magnetic field 0.02 T applied. We show that the capacitance enhancement is due to the polarization coupling between dielectric layer and ionic liquid layer.

  1. Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials.

    Science.gov (United States)

    Andryieuski, Andrei; Kuznetsova, Svetlana M; Zhukovsky, Sergei V; Kivshar, Yuri S; Lavrinenko, Andrei V

    2015-08-27

    We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric resonances in a metamaterial consisting of periodically positioned water-filled reservoirs. The proposed water-based metamaterials can find applications not only as cheap and ecological microwave devices, but also in optical and terahertz metamaterials prototyping and educational lab equipment.

  2. Effects of addictive substances during pregnancy and infancy and their analysis in biological materials.

    Science.gov (United States)

    Płotka, Justyna; Narkowicz, Sylwia; Polkowska, Zaneta; Biziuk, Marek; Namieśnik, Jacek

    2014-01-01

    The use of addictive substances during pregnancy is a serious social problem, not only because of effects on the health of the woman and child, but also because drug or alcohol dependency detracts from child care and enhances the prospect of child neglect and family breakdown. Developing additive substance abuse treatment programs for pregnant women is socially important and can help ensure the health of babies, prevent subsequent developmental and behavioral problems (i.e., from intake of alcohol or other additive substances such as methamphetamine, cocaine,or heroine) and can reduce addiction costs to society. Because women of childbearing age often abuse controlled substances during their pregnancy, it is important to undertake biomonitoring of these substances in biological samples taken from the pregnant or nursing mother (e.g., blood, urine,hair, breast milk, sweat, oral fluids, etc.), from the fetus and newborn (e.g., meconium,cord blood, neonatal hair and urine) and from both the mother and fetus (i.e.,amniotic fluids and placenta). The choice of specimens to be analyzed is determined by many factors; however, the most important is knowledge of the chemical and physical characteristics of a substance and the route of it administration. Maternal and neonatal biological materials reflect exposures that occur over a specific time period, and each of these biological specimens has different advantages and disadvantages,in terms of accuracy, time window of exposure and cost/benefit ratio.Sampling the placenta may be the most important biomonitoring choice for assessing in utero exposure to addictive substances. The use of the placenta in scientific research causes a minimum of ethical problems, partly because its sampling is noninvasive, causes no harm to mother or child, and partly because, in any case,placentas are discarded and incinerated after birth. Such samples, when properly analyzed, may provide key essential information about fetal exposure to toxic

  3. Numerical modelling of thermal effects on biological tissue during laser-material interaction

    Science.gov (United States)

    Latinovic, Z.; Sreckovic, M.; Janicijevic, M.; Ilic, J.; Radovanovic, J.

    2014-09-01

    Among numerous methods of the modelling of laser interaction with the material equivalent of biological tissue (including macroscopic and microscopic cell interaction), the case of pathogenic prostates is chosen to be studied. The principal difference between the inorganic and tissue equivalent material is the term which includes blood flow. Thermal modelling is chosen for interaction mechanisms, i.e. bio-heat equation. It was noticed that the principal problems are in selecting appropriate numerical methods, available mathematical program packages and finding all exact parameters for performing the needed calculations. As principal parameters, among them density, heat conduction, and specific heat, there are many other parameters which depend on the chosen approach (there could be up to 20 parameters, among them coefficient of time scaling, arterial blood temperature, metabolic heat source, etc). The laser type, including its wavelength which defines the quantity of absorbed energy and dynamic of irradiation, presents the term which could be modulated for the chosen problem. In this study, the program Comsol Multiphysics 3.5 is used in the simulation of prostate exposed to Nd3+:YAG laser in its fundamental mode.

  4. Fabrics with tunable oleophobicity

    OpenAIRE

    McKinley, Gareth H.; Choi, Wonjae; Cohen, Robert E.; Tuteja, Anish; Chhatre, Shreerang S.; Mabry, Joseph M.

    2009-01-01

    A simple “dip-coating” process that imbues oleophobicity to various surfaces that inherently possess re-entrant texture, such as commercially available fabrics, is reported. These dip-coated fabric surfaces exhibit reversible, deformation-dependent, tunable wettability, including the capacity to switch their surface wetting properties (between super-repellent and super-wetting) against a wide range of polar and nonpolar liquids.

  5. Fast, electrically tunable filters for hyperspectral imaging

    Science.gov (United States)

    Liberman, V.; Parameswaran, L.; Gear, C.; Cabral, A.; Rothschild, M.

    2014-06-01

    Tunable, narrow-wavelength spectral filters with a ms response in the mid-wave/long-wave infrared (MW/LWIR) are an enabling technology for hyperspectral imaging systems. Few commercial off-the-shelf (COTS) components for this application exist, including filter wheels, movable gratings, and Fabry-Perot (FP) etalon-based devices. These devices can be bulky, fragile and often do not have the required response speed. Here, we present a fundamentally different approach for tunable reflective IR filters, based on coupling subwavelength plasmonic antenna arrays with liquid crystals (LCs). Our device operates in reflective mode and derives its narrow bandwidth from diffractive coupling of individual antenna elements. The wavelength tunability of the device arises from electrically-induced re-orientation of the LC material in intimate contact with antenna array. This re-orientation, in turn, induces a change in the local dielectric environment of the antenna array, leading to a wavelength shift. We will first present results of full-field optimization of micron-size antenna geometries to account for complex 3D LC anisotropy. We have fabricated these antenna arrays on IR-transparent CaF2 substrates utilizing electron beam lithography, and have demonstrated tunability using 5CB, a commercially available LC. However, the design can be extended to high-birefringence liquid crystals for an increased tuning range. Our initial results demonstrate <60% peak reflectance in the 4- 6 μm wavelength range with a tunability of 0.2 μm with re-orientation of the surface alignment layers. Preliminary electrical switching has been demonstrated and is being optimized.

  6. Solid phase immobilization of optically responsive liposomes insol-gel materials for chemical and biological sensing

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, Stacey A.; Charych, Deborah H.; Loy, Douglas A.; Sasaki, Darryl Y.

    1997-04-01

    Liposomes enhanced with surface recognition groups have previously been found to have high affinity for heavy metal ions and virus particles with unique fluorescent and colorimetric responses, respectively. These lipid aggregate systems have now been successfully immobilized in a silica matrix via the sol-gel method, affording sensor materials that are robust, are easily handled, and offer optical clarity. The mild processing conditions allow quantitative entrapment of preformed liposomes without modification of the aggregate structure. Lipid extraction studies of immobilized nonpolymerized liposomes showed no lipid leakage in aqueous solution over a period of 3 months. Heavy metal fluorescent sensor materials prepared with 5 percent N-[8-[1-octadecyl-2-(9-(1-pyrenyl)nonyl)-rac-glyceroyl]-3,6-dioxaoctyl]imino acid/distearylphosphatidylcholineliposomes exhibited a 4-50-fold enhancement in sensitivity to various metal ions compared to that of the liposomes in free solution. Through ionic attraction the anionic silicate surface, at the experimental pH of 7.4, may act as a preconcentrator of divalent metal ions, boosting the gel's internal metal concentration. Entrapped sialic acid-coated polydiacetylene liposomes responded with colorimetric signaling to influenza virus X31, although slower than the free liposomes in solution. The successful transport of the virus (50-100 nm diameter) reveals a large pore diameter of the gel connecting the liposome to the bulk solution. The porous and durable silica matrix additionally provides a protective barrier to biological attack (bacterial, fungal) and allows facile recycling of the liposome heavy metal sensor.

  7. Chemical modifiers in arsenic determination in biological materials by tungsten coil electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, C.G.; Huerta, V.N.; Neira, J.Y. [Departamento de Analisis Instrumental, Facultad de Farmacia, Universidad de Concepcion, P.O. Box 237, Concepcion (Chile)

    2004-01-01

    Palladium, iridium, and rhodium are evaluated as possible chemical modifiers in the determination of As in digest solutions of biological materials (human hair and clam) by tungsten coil electrothermal atomic absorption spectrophotometry (TCA-AAS). The modifier in solution was applied onto the coil and thermally pre-reduced; the pre-reduction conditions, the amount of modifier, and the thermal program were optimized. Palladium was not satisfactory, whereas Ir and Rh were effective modifiers and rendered better relative sensitivity for As by a factor of 1.4 and 1.9, respectively compared to the case without modifier. Upon optimization of thermal conditions for As in pre-reduced Ir (2.0 {mu}g) and Rh (2.0 {mu}g) modifiers and in the digest solutions of the study matrices, Rh (2.0 {mu}g) was more effective modifier and was selected as such. The mean within-day repeatability was 2.8% in consecutive measurements (25-100 {mu}g L{sup -1}) (3 cycles, each of n=6) and confirmed good short-term stability of the absorbance measurements. The mean reproducibility was 4.4% (n=20 in a 3-day period) and the detection limit (3{sigma}{sub blank}/slope) was 29 pg (n=15). The useful coil lifetime in Rh modifier was extended to 300-400 firings. Validation was by determination of As in the certified reference material (CRM) of ''Oyster tissue'' solution with a percentage relative error (E{sub rel}%) of 2% and percentage relative standard deviation (RSD%) of 3% (n=4), and by analytical recovery of As spiked in CRM of human hair [94{+-}8% (n=4)]. The methodology is simple, fast (sample readout frequency 21 h{sup -1}), reliable, of low cost, and was applied to the determination of As in hair samples of exposed and unexposed workers. (orig.)

  8. Lightweight Tunable Infrared Filter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Michigan Aerospace Corporation has developed spaceflight qualified compact tunable Fabry-Perot interferometers for a number of applications, from ranging direct...

  9. Technique for examining biological materials using diffuse reflectance spectroscopy and the kubelka-munk function

    Energy Technology Data Exchange (ETDEWEB)

    Alfano, Robert R.; Yang, Yuanlong

    2003-09-02

    Method and apparatus for examining biological materials using diffuse reflectance spectroscopy and the Kubelka-Munk function. In one aspect, the method is used to determine whether a tissue sample is cancerous or not and comprises the steps of (a) measuring the diffuse reflectance from the tissue sample at a first wavelength and at a second wavelength, wherein the first wavelength is a wavelength selected from the group consisting of 255-265 nm and wherein the second wavelength is a wavelength selected from the group consisting of 275-285 nm; (b) using the Kubelka-Munk function to transform the diffuse reflectance measurement obtained at the first and second wavelengths; and (c) comparing a ratio or a difference of the transformed Kubelka-Munk measurements at the first and second wavelengths to appropriate standards determine whether or not the tissue sample is cancerous. One can use the spectral profile of KMF between 250 nm to 300 nm to determine whether or not the tissue sample is cancerous or precancerous. According to the value at the first and second wavelengths determine whether or not the malignant tissue is invasive or mixed invasive and in situ or carcinoma in situ.

  10. Sample sizing of biological materials analyzed by energy dispersion X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Jose D.S.; Franca, Elvis J.; Magalhaes, Marcelo R.L.; Almeida, Marcio E.S.; Hazin, Clovis A., E-mail: dan-paiva@hotmail.com, E-mail: ejfranca@cnen.gov.br, E-mail: marcelo_rlm@hotmail.com, E-mail: maensoal@yahoo.com.br, E-mail: chazin@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2013-07-01

    Analytical portions used in chemical analyses are usually less than 1g. Errors resulting from the sampling are barely evaluated, since this type of study is a time-consuming procedure, with high costs for the chemical analysis of large number of samples. The energy dispersion X-ray fluorescence - EDXRF is a non-destructive and fast analytical technique with the possibility of determining several chemical elements. Therefore, the aim of this study was to provide information on the minimum analytical portion for quantification of chemical elements in biological matrices using EDXRF. Three species were sampled in mangroves from the Pernambuco, Brazil. Tree leaves were washed with distilled water, oven-dried at 60 deg C and milled until 0.5 mm particle size. Ten test-portions of approximately 500 mg for each species were transferred to vials sealed with polypropylene film. The quality of the analytical procedure was evaluated from the reference materials IAEA V10 Hay Powder, SRM 2976 Apple Leaves. After energy calibration, all samples were analyzed under vacuum for 100 seconds for each group of chemical elements. The voltage used was 15 kV and 50 kV for chemical elements of atomic number lower than 22 and the others, respectively. For the best analytical conditions, EDXRF was capable of estimating the sample size uncertainty for further determination of chemical elements in leaves. (author)

  11. The biological impacts of ingested radioactive materials on the pale grass blue butterfly.

    Science.gov (United States)

    Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Tanahara, Akira; Otaki, Joji M

    2014-05-15

    A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.

  12. Spatial resolution of electron probe X-ray microanalysis on sections of organic (biological) material

    Energy Technology Data Exchange (ETDEWEB)

    Krefting, E.-R.; Felsmann, M.; Recker, A.; Feja, B.; Hoehling, H.J.; Reichelt, R. [Institut fuer Medizinische Physik und Biophysik, Westfaelische Wilhelms-Universitaet, Robert-Koch-Str. 31, 48149 Muenster (Germany); Reimer, L. [Physikalisches Institut, Westfaelische Wilhelms-Universitaet, Wilhelm-Klm-Str. 10, 48149 Muenster (Germany)

    1999-05-01

    A locally enhanced element concentration influences the result of an X-ray microanalysis at a neighbouring position. This influence was investigated for the first time systematically in organic (biological) material using sections of epoxy resin (thickness 0.5-2.5 {mu}m) containing a layer of pure gold. Wavelength and energy dispersive spectrometers were applied to analyse the X-rays generated by 15-35 keV electrons. Characteristic X-rays could be detected up to distances of several {mu}m from the gold layer. For example, for a 2.4 {mu}m thick section and 35 keV electrons the measured apparent gold concentration was above 0.1% (weight% per dry mass) at a distance of 10 {mu}m. Thus, the lateral resolution may be not better than a multiple of the section thickness. The apparent gold concentration at a given distance is proportional to the specimen thickness and increases with increasing electron energy. Monte Carlo simulations confirm the experimental results. The influence of a local enrichment depends on the particular specimen properties (e.g. thickness, density, mean atomic number), the electron energy, and the geometry of the detector with respect to the specimen. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  13. The biological impacts of ingested radioactive materials on the pale grass blue butterfly

    Science.gov (United States)

    Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Tanahara, Akira; Otaki, Joji M.

    2014-05-01

    A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.

  14. Collaborative Research. Fundamental Science of Low Temperature Plasma-Biological Material Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David Barry [Univ. California, Berkeley, CA (United States); Oehrlein, Gottlieb [Univ. of Maryland, College Park, MD (United States)

    2014-09-01

    atmospheric pressure using several types of low temperature plasma sources, for which radical induced interactions generally dominate due to short mean free paths of ions and VUV photons. For these conditions we demonstrated the importance of environmental interactions when atmospheric pressure plasma sources are used to modify biomolecules. This is evident from both gas phase characterization data and in-situ surface characterization of treated biomolecules. Environmental interactions can produce unexpected outcomes due to the complexity of reactions of reactive species with the atmosphere which determines the composition of reactive fluxes and atomistic changes of biomolecules. Overall, this work clarified a richer spectrum of scientific opportunities and challenges for the field of low temperature plasma-biomolecule surface interactions than initially anticipated, in particular for plasma sources operating at atmospheric pressure. The insights produced in this work, e.g. demonstration of the importance of environmental interactions, are generally important for applications of APP to materials modifications. Thus one major contributions of this research has been the establishment of methodologies to more systematically study the interaction of plasma with bio-molecules. In particular, our studies of atmospheric pressure plasma sources using very well-defined experimental conditions enabled to combine atomistic surface modifications of biomolecules with changes in their biological function. The clarification of the role of ions, VUV photons and radicals in deactivation of biomolecules during low pressure and atmospheric pressure plasma-biomolecule interaction has broad implications, e.g. for the emerging field of plasma medicine. The development of methods to detect the effects of plasma treatment on immune-active biomolecules will be helpful in many future studies.

  15. Enhanced stability and local structure in biologically relevant amorphous materials containing pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Slater, Colin; Laurencin, Danielle; Burnell, Victoria; Smith, Mark E.; Grover, Liam M.; Hriljac, Joseph A.; Wright, Adrian J. (CNRS-UMR); (Birmingham UK)

    2012-10-25

    There is increasing evidence that amorphous inorganic materials play a key role in biomineralisation in many organisms, however the inherent instability of synthetic analogues in the absence of the complex in vivo matrix limits their study and clinical exploitation. To address this, we report here an approach that enhances long-term stability to >1 year of biologically relevant amorphous metal phosphates, in the absence of any complex stabilizers, by utilizing pyrophosphates (P{sub 2}O{sub 7}{sup 4-}); species themselves ubiquitous in vivo. Ambient temperature precipitation reactions were employed to synthesise amorphous Ca{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O and Sr{sub 2}P{sub 2}O{sub 7}.nH{sub 2}O (3.8 < n < 4.2) and their stability and structure were investigated. Pair distribution functions (PDF) derived from synchrotron X-ray data indicated a lack of structural order beyond 8 {angstrom} in both phases, with this local order found to resemble crystalline analogues. Further studies, including {sup 1}H and {sup 31}P solid state NMR, suggest the unusually high stability of these purely inorganic amorphous phases is partly due to disorder in the P-O-P bond angles within the P{sub 2}O{sub 7} units, which impede crystallization, and to water molecules, which are involved in H-bonds of various strengths within the structures and hamper the formation of an ordered network. In situ high temperature powder X-ray diffraction data indicated that the amorphous nature of both phases surprisingly persisted to 450 C. Further NMR and TGA studies found that above ambient temperature some water molecules reacted with P{sub 2}O{sub 7} anions, leading to the hydrolysis of some P-O-P linkages and the formation of HPO{sub 4}{sup 2-} anions within the amorphous matrix. The latter anions then recombined into P{sub 2}O{sub 7} ions at higher temperatures prior to crystallization. Together, these findings provide important new materials with unexplored potential for enzyme

  16. Application of a radiometric method for evaluation of loss of salicylic acid during isolation from biologic material.

    Science.gov (United States)

    Ostrowski, A

    1983-01-01

    A radiometric method for evaluation of loss of salicylic acid in the process of isolation from biologic material is described. According to this study the mean loss during the total process of isolation amounts to 33.59%, the specific values being 19.47% during protein precipitation, 10.68% during extraction, and 3.44% during evaporation of solvent.

  17. Combustion method for assay of biological materials labeled with carbon-14 or tritium, or double-labeled

    Science.gov (United States)

    Huebner, L. G.; Kisieleski, W. E.

    1969-01-01

    Dry catalytic combustion at high temperatures is used for assaying biological materials labeled carbon-14 and tritium, or double-labeled. A modified oxygen-flask technique is combined with standard vacuum-line techniques and includes convenience of direct in-vial collection of final combustion products, giving quantitative recovery of tritium and carbon-14.

  18. Fabrication of tunable superhydrophobic surfaces

    Science.gov (United States)

    Shiu, Jau-Ye; Kuo, Chun-Wen; Chen, Peilin

    2004-02-01

    Inspired by the water-repellent behavior of the micro- and nano-structured plant surfaces, superhydrophobic materials, with a water contact larger than 150 degree, have received a lot of research attentions recently. It has been suggested that contamination, oxidation and current conduction can be inhibited on such superhydrophobic surfaces, and the flow resistance in the microfluidic channels can also be reduced using super water-repellent materials. In order to prepare superhydrophobic materials, we have developed two simple approaches for fabricating tunable superhydrophobic surfaces using nanosphere lithography and plasma etching. In the first case, the polystyrene nanospheres were employed to create well-ordered rough surfaces covered by gold and alkylthiols. Using oxygen plasma treatment, the topmost surface area can be modified systematically, as the result the water contact angle on such surfaces can be tuned from 132 to 170 degree. The water contact angles measured on these surfaces can be modeled by the Cassie"s formulation without any adjustable parameter. In the second approach, thin films of Teflon were spin-coated on the substrate surfaces and treated by oxygen plasma. Superhydrophobic surfaces with water contact angle up to 170 degree were obtained by this approach. If the ITO glasses were used as the substrates, the hydrophobicity of the surface can be tuned by applying DC voltage. Water contact angle can be adjusted from 158 degree to 38 degree.

  19. Advances in tunable solid-state lasers

    Energy Technology Data Exchange (ETDEWEB)

    De Shazer, L.G.

    1987-02-01

    Continuing problems in solid-state lasers including low efficiency and lack of frequency diversity have limited their applicability in past years. Through recent materials technological developments, both of these problems are starting to be solved. Many new tunable lasers operating at wavelengths ranging from 650 nm to 3..mu..m have been demonstrated in the laboratory, and applications now are being considered for space and terrestrial remote sensors. Comparable progress also has been made towards more efficient solid-state lasers, for example, new neodymium (Nd) lasers having 6% overall efficiency. These advances in solid-state lasers depend on the interplay between the fields of materials science and lasers. To develop this association between the two disciplines, an Optical Society of America (OSA) topical meeting on Tunable Solid State lasers was held in Zigzag, Oreg. As well as covering research and development of tunable lasers based on ion-doped dielectric solids, this meeting discussed crystal growth and laser applications. Also included were rare earth laser sources operating at new wavelengths, an expansion in the agenda from the first meeting, held last year in May in Arlington, Va.

  20. Optically pumped 1550nm wavelength tunable MEMS VCSEL

    DEFF Research Database (Denmark)

    Sahoo, Hitesh Kumar; Ansbæk, Thor; Ottaviano, Luisa

    2016-01-01

    The paper presents the design and fabrication of an optically pumped 1550nm tunable MEMS VCSEL with anenclosed MEMS. The MEMS is defined in SOI and the active material, an InP wafer with quantum wells arebonded to the SOI and the last mirror is made from the deposition of dielectric materials...

  1. Indium arsenide as a material for biological applications: Assessment of surface modifications, toxicity, and biocompatibility

    Science.gov (United States)

    Jewett, Scott A.

    III-V semiconductors such as InAs have recently been employed in a variety of applications where the electronic and optical characteristics of traditional, silicon-based materials are inadequate. InAs has a narrow band gap and very high electron mobility in the near-surface region, which makes it very attractive for high performance transistors, optical applications, and chemical sensing. However, InAs forms an unstable surface oxide layer in ambient conditions, which can corrode over time and leach toxic indium and arsenic components. Current research has gone into making InAs more attractive for biological applications through passivation of the surface by adlayer adsorption. In particular, wet-chemical methods are current routes of exploration due to their simplicity, low cost, and flexibility in the type of passivating molecule. This dissertation focuses on surface modifications of InAs using wet-chemical methods in order to further its use in biological applications. First, the adsorption of collagen binding peptides and mixed peptide/thiol adlayers onto InAs was assessed. X-ray photoelectron spectroscopy (XPS) along with atomic force microscopy (AFM) data suggested that the peptides successfully adsorbed onto InAs, but were only able to block oxide regrowth to a relatively low extent. This low passivation ability is due to the lack of covalent bonds of the peptide to InAs, which are necessary to effectively block oxide regrowth. The addition of a thiol, in the form of mixed peptide/thiol adlayers greatly enhanced passivation of InAs while maintaining peptide presence on the surface. Thiols form tight, covalent bonds with InAs, which prevents oxide regrowth. The presence of the collagen-binding peptide on the surface opens the door to subsequent modification with collagen or polyelectrolyte-based adlayers. Next, the stability and toxicity of modified InAs substrates were determined using inductively coupled plasma mass spectrometry (ICP-MS) and zebrafish

  2. Updated Lagrangian finite element formulations of various biological soft tissue non-linear material models: a comprehensive procedure and review.

    Science.gov (United States)

    Townsend, Molly T; Sarigul-Klijn, Nesrin

    2016-01-01

    Simplified material models are commonly used in computational simulation of biological soft tissue as an approximation of the complicated material response and to minimize computational resources. However, the simulation of complex loadings, such as long-duration tissue swelling, necessitates complex models that are not easy to formulate. This paper strives to offer the updated Lagrangian formulation comprehensive procedure of various non-linear material models for the application of finite element analysis of biological soft tissues including a definition of the Cauchy stress and the spatial tangential stiffness. The relationships between water content, osmotic pressure, ionic concentration and the pore pressure stress of the tissue are discussed with the merits of these models and their applications.

  3. Enhancement in biological response of Ag-nano composite polymer membranes using plasma treatment for fabrication of efficient bio materials

    Science.gov (United States)

    Agrawal, Narendra Kumar; Sharma, Tamanna Kumari; Chauhan, Manish; Agarwal, Ravi; Vijay, Y. K.; Swami, K. C.

    2016-05-01

    Biomaterials are nonviable material used in medical devices, intended to interact with biological systems, which are becoming necessary for the development of artificial material for biological systems such as artificial skin diaphragm, valves for heart and kidney, lenses for eye etc. Polymers having novel properties like antibacterial, antimicrobial, high adhesion, blood compatibility and wettability are most suitable for synthesis of biomaterial, but all of these properties does not exist in any natural or artificial polymeric material. Nano particles and plasma treatment can offer these properties to the polymers. Hence a new nano-biomaterial has been developed by modifying the surface and chemical properties of Ag nanocomposite polymer membranes (NCPM) by Argon ion plasma treatment. These membranes were characterized using different techniques for surface and chemical modifications occurred. Bacterial adhesion and wettability were also tested for these membranes, to show direct use of this new class of nano-biomaterial for biomedical applications.

  4. Ferromagnetic resonance for the quantification of superparamagnetic iron oxide nanoparticles in biological materials

    Directory of Open Access Journals (Sweden)

    Lionel F Gamarra

    2010-03-01

    Full Text Available Lionel F Gamarra1,2, Antonio J daCosta-Filho3, Javier B Mamani1, Rita de Cassia Ruiz4, Lorena F Pavon1, Tatiana T Sibov1, Ernanni D Vieira3, André C Silva1, Walter M Pontuschka5, Edson Amaro Jr1,21Instituto Israelita de Ensino e Pesquisa Albert Einstein, IIEPAE, São Paulo, Brazil; 2Instituto de Radiologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil; 3Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil; 4Instituto Butantan, São Paulo, Brazil; 5Instituto de Física, Universidade de São Paulo, São Paulo, BrazilAbstract: The aim of the present work is the presentation of a quantification methodology for the control of the amount of superparamagnetic iron oxide nanoparticles (SPIONs administered in biological materials by means of the ferromagnetic resonance technique (FMR applied to studies both in vivo and in vitro. The in vivo study consisted in the analysis of the elimination and biodistribution kinetics of SPIONs after intravenous administration in Wistar rats. The results were corroborated by X-ray fluorescence. For the in vitro study, a quantitative analysis of the concentration of SPIONs bound to the specific AC133 monoclonal antibodies was carried out in order to detect the expression of the antigenic epitopes (CD133 in stem cells from human umbilical cord blood. In both studies FMR has proven to be an efficient technique for the SPIONs quantification per volume unit (in vivo or per labeled cell (in vitro.Keywords: quantification, FMR, ferrofluid, biodistribution, nanoparticles

  5. Cut and puncture accidents involving health care workers exposed to biological materials

    Directory of Open Access Journals (Sweden)

    Cristiane Grande Gimenez Marino

    2001-10-01

    Full Text Available The first report of occupational acquisition of HIV appeared in 1984, and, by June, 1997, the Centers for Disease Control and Prevention (CDC had reported 52 documented cases of sero-conversion following occupational exposure to HIV-1 by health care workers of those cases. 47 (90.3% were exposed to blood. The most frequent type of accident reported was percutaneous needlestick injury. Prospective studies have estimated that the risk of HIV transmission following percutaneous exposure to infected blood is 0.3% (Confidence Interval 95% = 0.2% to 0.5%. Following a mucous membrane exposure, the risk is 0.09% (CI 95% = 0.006% to 0.5%. The risk of hepatitis B acquisition ranges from 6% to 30%, and hepatitis C acquisition, 3% to 10%. Since 1992, the São Paulo Hospital's Hospital Infection Prevention and Control Service (SPCIH has notified and treated all workers exposed to accidents involving biological materials. In the last six years, we have handled approximately 1,300 cases of reported accidents, of which 90% were percutaneous, most involving needlesticks. Such cases were frequently caused by the inadequate disposal and recapping of needles. In these accidents, 20% of the source patients were HIV positive, 10% were hepatitis C positive, and 7.6% were hepatitis B positive. This review summarizes the guidelines for a standardized response when dealing with accidents involving health care workers. Transmission of hepatitis B and HIV can be reduced if adequate preventive measures are taken in advance. If proper prophylaxis is not being done, it should be initiated immediately.

  6. Tunable nonlinear graphene metasurfaces

    CERN Document Server

    Smirnova, Daria A; Kivshar, Yuri S; Khanikaev, Alexander B

    2015-01-01

    We introduce the concept of nonlinear graphene metasurfaces employing the controllable interaction between a graphene layer and a planar metamaterial. Such hybrid metasurfaces support two types of subradiant resonant modes, asymmetric modes of structured metamaterial elements ("metamolecules") and graphene plasmons exhibiting strong mutual coupling and avoided dispersion crossing. High tunability of graphene plasmons facilitates strong interaction between the subradiant modes, modifying the spectral position and lifetime of the associated Fano resonances. We demonstrate that strong resonant interaction, combined with the subwavelength localization of plasmons, leads to the enhanced nonlinear response and high efficiency of the second-harmonic generation.

  7. Tunable multiwalled nanotube resonator

    Science.gov (United States)

    Zettl, Alex K.; Jensen, Kenneth J.; Girit, Caglar; Mickelson, William E.; Grossman, Jeffrey C.

    2011-03-29

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  8. Quantification of ultraviolet photon emission from interaction of charged particles in materials of interest in radiation biology research

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Syed Bilal, E-mail: ahmadsb@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada); Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan); McNeill, Fiona E., E-mail: fmcneill@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada); Prestwich, William V., E-mail: prestwic@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada); Byun, Soo Hyun, E-mail: soohyun@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada); Seymour, Colin, E-mail: seymouc@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada); Mothersill, Carmel E., E-mail: mothers@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, University of McMaster, Hamilton, ON (Canada)

    2014-01-15

    In radiation biology experiments often cells are irradiated using charged particles with the intention that only a specified number of cells are hit by the primary ion track. However, in doing so several other materials such as the cell container and the growth media etc. are also irradiated, and UV radiation emitted from these materials can potentially interact with the cells. We have hypothesized that some “bystander effects” that are thought to be chemically mediated, may be, in fact, a physical effect, where UV is interacting with non-targeted cells. Based upon our hypothesis we quantified the emission of UV from Polypropylene, Mylar, Teflon, and Cellophane which are all commonly used materials in radiation biology experiments. Additionally we measured the NIST standard materials of Oyster tissue and Citrus leaves as these powdered materials are derived from living cells. Protons accelerated up to an energy of 2.2 MeV, in a 3 MV Van de Graff accelerator, were used for irradiation. Beam current was kept to 10 nA, which corresponds to a proton fluence rate of 2.7 × 10{sup 10} protons mm{sup −2} s{sup −1}. All the materials were found to emit light at UV frequencies and intensities that were significant enough to conduct a further investigation for their biological consequences. Mylar and polypropylene are commonly used in radiation induced bystander effect studies and are considered to be non-fluorescent. However our study showed that this is not the case. Significant luminescence observed from the irradiated NIST standard reference materials for Oyster tissue and Citrus leaves verified that the luminescence emission is not restricted only to the polymeric materials that are used to contain cells. It can also occur from ion interactions within the cells as well.

  9. Optimal design of tunable phononic bandgap plates under equibiaxial stretch

    Science.gov (United States)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, M. S.; Guest, James K.

    2016-05-01

    Design and application of phononic crystal (PhCr) acoustic metamaterials has been a topic with tremendous growth of interest in the last decade due to their promising capabilities to manipulate acoustic and elastodynamic waves. Phononic controllability of waves through a particular PhCr is limited only to the spectrums located within its fixed bandgap frequency. Hence the ability to tune a PhCr is desired to add functionality over its variable bandgap frequency or for switchability. Deformation induced bandgap tunability of elastomeric PhCr solids and plates with prescribed topology have been studied by other researchers. Principally the internal stress state and distorted geometry of a deformed phononic crystal plate (PhP) changes its effective stiffness and leads to deformation induced tunability of resultant modal band structure. Thus the microstructural topology of a PhP can be altered so that specific tunability features are met through prescribed deformation. In the present study novel tunable PhPs of this kind with optimized bandgap efficiency-tunability of guided waves are computationally explored and evaluated. Low loss transmission of guided waves throughout thin walled structures makes them ideal for fabrication of low loss ultrasound devices and structural health monitoring purposes. Various tunability targets are defined to enhance or degrade complete bandgaps of plate waves through macroscopic tensile deformation. Elastomeric hyperelastic material is considered which enables recoverable micromechanical deformation under tuning finite stretch. Phononic tunability through stable deformation of phononic lattice is specifically required and so any topology showing buckling instability under assumed deformation is disregarded. Nondominated sorting genetic algorithm (GA) NSGA-II is adopted for evolutionary multiobjective topology optimization of hypothesized tunable PhP with square symmetric unit-cell and relevant topologies are analyzed through finite

  10. Digital learning material for experimental design and model building in molecular biology

    NARCIS (Netherlands)

    Aegerter-Wilmsen, T.

    2005-01-01

    Designing experimental approaches is a major cognitive skill in molecular biology research, and building models, including quantitative ones, is a cognitive skill which is rapidly gaining importance. Since molecular biology education at university level is aimed at educating future researchers, we c

  11. Radioprotection, biological effects of the radiations and security in the handling of radioactive material

    CERN Document Server

    Teran, M

    2000-01-01

    The development of the philosophy of the radioprotection is dependent on the understanding of the effects of the radiation in the man. Behind the fact that the radiation is able to produce biological damages there are certain factors with regard to the biological effects of the radiations that determine the boarding of the radioprotection topics.

  12. EDITORIAL: Nanotechnology at the interface of cell biology, materials science and medicine Nanotechnology at the interface of cell biology, materials science and medicine

    Science.gov (United States)

    Engel, Andreas; Miles, Mervyn

    2008-09-01

    The atomic force microscope (AFM) and related scanning probe microscopes have become resourceful tools to study cells, supramolecular assemblies and single biomolecules, because they allow investigations of such structures in native environments. Quantitative information has been gathered about the surface structure of membrane proteins to lateral and vertical resolutions of 0.5 nm and 0.1 nm, respectively, about the forces that keep protein-protein and protein-nucleic acid assemblies together as well as single proteins in their native conformation, and about the nanomechanical properties of cells in health and disease. Such progress has been achieved mainly because of constant development of AFM instrumentation and sample preparation methods. This special issue of Nanotechnology presents papers from leading laboratories in the field of nanobiology, covering a wide range of topics in the form of original and novel scientific contributions. It addresses achievements in instrumentation, sample preparation, automation and in biological applications. These papers document the creativity and persistence of researchers pursuing the goal to unravel the structure and dynamics of cells, supramolecuar structures and single biomolecules at work. Improved cantilever sensors, novel optical probes, and quantitative data on supports for electrochemical experiments open new avenues for characterizing biological nanomachines down to the single molecule. Comparative measurements of healthy and metastatic cells promise new methods for early detection of tumors, and possible assessments of drug efficacy. High-speed AFMs document possibilities to monitor crystal growth and to observe large structures at video rate. A wealth of information on amyloid-type fibers as well as on membrane proteins has been gathered by single molecule force spectroscopy—a technology now being automated for large-scale data collection. With the progress of basic research and a strong industry supporting

  13. The protein and peptide mediated syntheses of non-biologically-produced oxide materials

    Science.gov (United States)

    Dickerson, Matthew B.

    Numerous examples exist in nature of organisms which have evolved the ability to produce sophisticated structures composed of inorganic minerals. Studies of such biomineralizing organisms have suggested that specialized biomolecules are, in part, responsible for the controlled formation of these structures. The research detailed in this dissertation is focused on the use of biomolecules (i.e., peptides and proteins) to form non-biologically produced materials under mild reaction conditions (i.e., neutral pH, aqueous solutions, and room temperature). The peptides utilized in the studies detailed in this dissertation were identified through the screening of single crystal rutile TiO2 substrates or Ge powder with a phagedisplayed peptide library. Twenty-one peptides were identified which possessed an affinity for Ge. Three of these twenty one peptides were tested for germania precipitation activity. Those peptides possessing a basic isoelectric point as well as hydroxyl- and imidazole-containing amino acid residues were found to be the most effective in precipitating amorphous germania from an alkoxide precursor. The phage-displayed peptide library screening of TiO2 substrates yielded twenty peptides. Four of these peptides, which were heavily enriched in histidine and/or basic amino acid residues, were found to possess signficant titania precipitation activity. The activity of these peptides was found to correlate with the number of positive charges they carried. The sequence of the most active of the library-identified peptides was modified to yield two additional peptides. The titania precipitation activity of these designed peptides was higher than the parent peptide, with reduced pH dependence. The titania materials generated by the library-identified and designed peptides were found to be composed of amorphous titania as well as <10 nm anatase and/or monoclinic TiO2 crystallites. The production of titania and zirconia resulting from the interaction of the

  14. Tunable Topological Phononic Crystals

    KAUST Repository

    Chen, Ze-Guo

    2016-05-27

    Topological insulators first observed in electronic systems have inspired many analogues in photonic and phononic crystals in which remarkable one-way propagation edge states are supported by topologically nontrivial band gaps. Such band gaps can be achieved by breaking the time-reversal symmetry to lift the degeneracy associated with Dirac cones at the corners of the Brillouin zone. Here, we report on our construction of a phononic crystal exhibiting a Dirac-like cone in the Brillouin zone center. We demonstrate that simultaneously breaking the time-reversal symmetry and altering the geometric size of the unit cell result in a topological transition that we verify by the Chern number calculation and edge-mode analysis. We develop a complete model based on the tight binding to uncover the physical mechanisms of the topological transition. Both the model and numerical simulations show that the topology of the band gap is tunable by varying both the velocity field and the geometric size; such tunability may dramatically enrich the design and use of acoustic topological insulators.

  15. A common basis for facilitated legitimate exchange of biological materials proposed by the European Culture Collections' Organisation

    Directory of Open Access Journals (Sweden)

    Dagmar Fritze

    2009-12-01

    Full Text Available Being charged with the task of accessioning and supplying of living microbiological material, microbial culture collections are institutions that play a central role between the interests of a variety of user communities. On the one side are the providers of living microbiological material, such as individual scientists, institutions and countries of origin and on the other side are the various kinds of recipients/users of cultures of microorganisms from academia and industry. Thus, providing access to high quality biological material and scientific services while at the same time observing donor countries' rights, intellectual property rights, biosafety and biosecurity aspects poses demanding challenges. E.g. donor countries rights relate to Article 15 of the Convention on Biological Diversity: "Contracting parties …. recognize the sovereign rights of states over their natural resources …. shall facilitate access to resources … and not impose restrictions that run counter to the aims of the Convention. Access to natural resources shall be by mutually agreed terms and subject to prior informed consent ..." The use of a proposed standard contract by culture collections is discussed as a way of contractually safeguarding the existing research commons, while observing the new rights established in the Convention on Biological Diversity as well as other existing and new legislation impacting on the accessibility of living microbial material.

  16. Novel synthesis of covalently linked silicon quantum dot–polystyrene hybrid materials: Silicon quantum dot–polystyrene polymers of tunable refractive index

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin-Kyu; Dung, Mai Xuan; Jeong, Hyun-Dam, E-mail: hdjeong@chonnam.ac.kr

    2014-11-14

    We present a new material design concept, silicon quantum dot (Si QD) polymers, for which surface-functionalized Si QDs can be regarded as a large monomer in the polymers. As a prototypical example, vinyl-functionalized Si QDs, i.e., divinylbenzene-capped Si QDs (DVB-Si QDs) synthesized by adopting divinylbenzene (DVB) capping molecule to the hydride-terminated Si QD (H-Si QD) via Pt-catalyzed hydrosilylation was introduced and polymerized with a styrene monomer to yield Si QD–polystyrene (Si QD–PS) polymers. To demonstrate controllability of the content of Si QDs in the polymers as in conventional polymers, three Si QD content varied Si QD–PS polymers were systematically prepared, named as Si QD–PS-A, Si QD–PS-B, and Si QD–PS-C. It has been demonstrated that the content of the Si QDs in the Si QD–PS polymers was well controlled by the amount of the DVB-Si QD used, as found to be 3.8 wt% (Si QD–PS-A), 10.0 wt% (Si QD–PS-B), 20.0 wt% (Si QD–PS-A), and 37.4 wt% (DVB-Si QD), which was deduced from TGA results. Thin films of the Si QD–PS polymers and the freestanding DVB-Si QDs were successfully fabricated by a spin-coating method and it was found that the refractive index of the thin films dried at 40 °C was linearly increased as the content of the Si QD in the polymers was increased from 1.586 (0 wt%), to 1.590 (3.8 wt%), to 1.592 (10.0 wt%), to 1.592 (20.0 wt%), and to 1.614 (37.4 wt%). - Highlights: • A new material design concept, Si QD polymer, is presented. • Freestanding vinyl-functionalized Si QD was synthesized as a monomer for polymer. • Si QD–PS polymers were synthesized by polymerization of styrene with vinyl-Si QD. • Concentration of Si QD in the polymer was well controlled by amount of Si QD used. • Refractive index of polymer thin films linearly increased with concentration of Si QD.

  17. BIOFILM FORMATION ON THE SURFACE OF MATERIALS AND MEDICAL PRODUCTS BY NOSOCOMIAL STRAINS ISOLATED FROM THE BIOLOGICAL SUBSTRATES OF PATIENTS

    Directory of Open Access Journals (Sweden)

    E. A. Nemets

    2013-01-01

    Full Text Available Aim. To study the ability of hospital-associated strains isolated from the biological substrates of patients oper- ated on under extracorporeal circulation, to form biofilms on the surface of medical materials and products. Materials and methods. The formation of biofilms of strains of Staphylococcus aureus, Serratia liquefaciens, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. isolated from the biological substrates of patients operated on under extracorporeal circulation, on different surfaces (politetraftorotilen, medical poly- ethylene, Polyoxybutirate-to-valerate, silicone, polyvinyl chloride, was studied by a modified method for the surface of the medical materials and products. Results. The influence of the material nature, as well as hydrophi- lization of the surface, on the ability of hospital-associated strains, isolated from the biological substrates of pa- tients operated on under extracorporeal circulation, to form biofilms is studied. It is shown that that certain strains exhibit an increased tendency to biofilm formation on more hydrophobic surfaces, e. g., Acinetobacter spp. At the same time the activity of Staphylococcus aureus on silicon surface (hydrophobic surface is minimal. Other strains almost equally form biofilms on hydrophilic and hydrophobic surfaces e.g. Serratia liquefaciens. It was also shown that the surface hydrophilization of PEG to 50% for all the studied strains leads to dramatic reduc- tion of biofilm formation. Conclusion. The tendency to form biofilms of a particular hospital-associated strain is individual and depends on the nature of the medical material and physical-chemical characteristics of its surface. Hydrophilization of the surface of the medical material is accompanied by a lowered risk of biofilm formation. 

  18. Protein viscosity, mineral fraction and staggered architecture cooperatively enable the fastest stress wave decay in load-bearing biological materials.

    Science.gov (United States)

    Qwamizadeh, Mahan; Zhang, Zuoqi; Zhou, Kun; Zhang, Yong Wei

    2016-07-01

    One of the key functions of load-bearing biological materials, such as bone, dentin and sea shell, is to protect their inside fragile organs by effectively damping dynamic impact. How those materials achieve this remarkable function remains largely unknown. Using systematic finite element analyses, we study the stress wave propagation and attenuation in cortical bone at the nanoscale as a model material to examine the effects of protein viscosity, mineral fraction and staggered architecture on the elastic wave decay. It is found that the staggered arrangement, protein viscosity and mineral fraction work cooperatively to effectively attenuate the stress wave. For a typical mineral volume fraction and protein viscosity, an optimal staggered nanostructure with specific feature sizes and layouts is able to give rise to the fastest stress wave decay, and the optimal aspect ratio and thickness of mineral platelets are in excellent agreement with experimental measurements. In contrary, as the mineral volume fraction or the protein viscosity goes much higher, the structural arrangement is seen having trivial effect on the stress wave decay, suggesting that the damping properties of the composites go into the structure-insensitive regime from the structure-sensitive regime. These findings not only significantly add to our understanding of the structure-function relationship of load-bearing biological materials, and but also provide useful guidelines for the design of bio-inspired materials with superior resistance to impact loading.

  19. Effect of weight fraction of different constituent elements on the total mass attenuation coefficients of biological materials

    Indian Academy of Sciences (India)

    Karamjit Singh; Charanjeet Singh; Parjit S Singh; Gurmel S Mudahar

    2002-07-01

    The mass attenuation coefficients, m, of biological materials have been studied as a function of weight fraction of constituent elements (hydrogen, carbon, oxygen and nitrogen). A considerable change in m is seen only in low energy region whereas no change is observed with the increasing percentage of constituent elements in high energy region up to 10 MeV. The results have been presented in graphical form.

  20. Mid-infrared tunable metamaterials

    Science.gov (United States)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A; Passmore, Brandon Scott; Jun, Young Chul

    2015-04-28

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  1. Tunable Imaging Filters in Astronomy

    CERN Document Server

    Bland-Hawthorn, J

    2000-01-01

    While tunable filters are a recent development in night time astronomy, they have long been used in other physical sciences, e.g. solar physics, remote sensing and underwater communications. With their ability to tune precisely to a given wavelength using a bandpass optimized for the experiment, tunable filters are already producing some of the deepest narrowband images to date of astrophysical sources. Furthermore, some classes of tunable filters can be used in fast telescope beams and therefore allow for narrowband imaging over angular fields of more than a degree over the sky.

  2. Biological properties of IRM with the addition of hydroxyapatite as a retrograde root filling material.

    Science.gov (United States)

    Owadally, I D; Chong, B S; Pitt Ford, T R; Wilson, R F

    1994-10-01

    The effect of adding 10% & 20% hydroxyapatite (HAP) on the antibacterial activity and cytotoxicity of IRM (Intermediate Restorative Material) when used as a retrograde root filling was compared with amalgam, a commonly used material. The antibacterial activity was assessed using the agar diffusion inhibitory test. Forty standardized pellets of each material were produced. Fresh materials, and materials aged for 1 week in sterile distilled water, were placed on blood agar plates inoculated with Streptococcus anginosus (milleri) or Enterococcus faecalis. The presence and diameter of zones of inhibition were recorded at intervals of 3, 7 and 10 days. There was no statistically significant overall difference in the response of the two bacteria tested. However, there were statistically significant overall differences in diameters of the zones of inhibition related to different materials, period of exposure and ageing of materials (P materials, fresh and aged. IRM and both the HAP-modified forms produced large zones of inhibition. Amalgam produced no measureable zones of inhibition whether aged or fresh, regardless of period of exposure and was different from the other materials (P material were produced and aged by storage in sterile distilled water for 72 h. Ten filters were included as controls. Amalgam produced a consistent cytotoxic score of 1, and the difference between amalgam and the other materials was statistically significant (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Development of New Didactic Materials for Teaching Science and Biology: The Importance of the New Education Practices

    Directory of Open Access Journals (Sweden)

    Camila O. Arent

    2009-01-01

    Full Text Available Problem statement: The creativity of teachers in the planning process of their classes for teaching science and biology may be an instigator to promote and stimulate learning. The science should be something that awakens curiosity in students to make learning pleasurable and increase their interest. The aim this research was to develop didactic materials for to help the teaching-learning process in the content of science and biology. Especially, those content about systematic that can not be very exciting and bring some difficulty for the involvement of students. Approach: Inspired in the Atlantic forest, which extends along the Brazilian coast and offers a diverse ecosystem, were created some materials that enable the interaction of teacher with students, which were: "memory of the Atlantic forest", "unmasking the Atlantic forest” and a “set of transparencies”. The first is composed of 25 cards each containing an image of a species of fauna or flora of the Atlantic forest, popular and scientific name. Complete the material, 25 letters with specific characteristics of each species. The second is a panel with the illustration of the incompleteness of the Atlantic forest ecosystem, featuring 10 pictures of animals that are hidden between the two sides of the panel and asked for 10 letters, which were answered to complete the ecosystem. The third is a set of transparencies containing information on the Atlantic, maps and data on the fauna and flora. The latter should be used to perform a preliminary discussion on the biodiversity of the Atlantic. Results: Results showed that these materials facilitate learning, as well as linking images of known species with their respective characteristics, makes the class interesting by providing the effective interaction of the group. Conclusion/Recommendation: These materials were used and well accepted by students of the course of biological science in the

  4. Gas chromatography of volatile fatty acids. Method involving separation from biological material by vacuum distillation.

    Science.gov (United States)

    Tyler, J E; Dibdin, G H

    1975-02-19

    A method is described for the quantitation of C2-C5 volatile fatty acids present in biological tissues. It involved recovery of the acids from their biological matrix by vacuum micro-distillation at room temperature, followed by gas phase separation of aqueous solutions on orthophosphoric acid-modified Phasepak Q columns. The subsequent gas chromatographic procedure resolved iso from normal isomers and showed a linear response for each volatile acid over the range 10-400 ng. There was no evidence of ghosting, isomer peak broadening, or peak tailing. Relative molar response values were shown to be linear with carbon number for all the volatile fatty acids studied.

  5. Photonic MEMS tunable laser sources

    Institute of Scientific and Technical Information of China (English)

    LIU Ai-qun

    2009-01-01

    This article covers laser configurations, design and experiments of photonic microelectromechanical systems (MEMS) tunable laser sources. Three different types of MEMS tunable lasers such as MEMS coupled-cavity lasers, injection-locked laser systems and dual-wavelength tunable lasers are demonstrated as examples of natural synergy of MEMS with photonics. The expansion and penetration of the MEMS technology to silicon optoelectronic creates on-chip optical systems at an unprecedented scale of integration. While producing better integration with robustness and compactness, MEMS improves the functionalities and specifications of laser chips. Additionally, MEMS tunable lasers are featured with small size, high tuning speed, wide tuning range and CMOS compatible integration, which broaden their applications to many fields.

  6. Novel hydrophobically associative polyacrylamide with tunable viscosity

    Institute of Scientific and Technical Information of China (English)

    Xu Feng Zhang; Wen Hui Wu

    2009-01-01

    Hydrophobically associative polyacrylamide (HAPAM) were prepared in aqueous solution by radical copolymerization of novel cationic surface-active monomer, dimethylhexadecyl(3-acrylamidopropyl)ammonium bromide (DMHAB), with acrylarnide (AM) in the presence of DMHAB/CTAB mixed micelles. The length of hydrophobic microblock (N_H) in HAPAM is controlled by the molar fraction of DMHAB in mixed micelles, which can be mediated by the ratio of CTAB to DMHAB. The results of steady-state fluorescence probe and viscometry experiments showed the ability of HAPAM association was determined by the length of the hydrophobic microblock. HAPAM with tunable association ability are promising materials for thickening agent.

  7. Tunable optical absorption in silicene molecules

    KAUST Repository

    Mokkath, Junais Habeeb

    2016-07-13

    Two-dimensional materials with a tunable band gap that covers a wide range of the solar spectrum hold great promise for sunlight harvesting. For this reason, we investigate the structural, electronic, and optical properties of silicene molecules using time dependent density functional theory. We address the influence of the molecular size, buckling, and charge state as well as that of a dielectric environment. Unlike planar graphene molecules, silicene molecules prefer to form low-buckled structures with strong visible to ultraviolet optical response. We also identify molecular plasmons.

  8. Tunable femtosecond Cherenkov fiber laser

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper

    2014-01-01

    We demonstrate electrically-tunable femtosecond Cherenkov fiber laser output at the visible range. Using an all-fiber, self-starting femtosecond Yb-doped fiber laser as the pump source and nonlinear photonic crystal fiber link as the wave-conversion medium, ultrafast, milliwatt-level, tunable...... and spectral isolated Cherenkov radiation at visible wavelengths are reported. Such a femtosecond Cherenkov laser source is promising for practical biophotonics applications....

  9. Tunable on chip optofluidic laser

    DEFF Research Database (Denmark)

    Bakal, Avraham; Vannahme, Christoph; Kristensen, Anders

    2016-01-01

    On chip tunable laser is demonstrated by realizing a microfluidic droplet array. The periodicity is controlled by the pressure applied to two separate inlets, allowing to tune the lasing frequency over a broad spectral range.......On chip tunable laser is demonstrated by realizing a microfluidic droplet array. The periodicity is controlled by the pressure applied to two separate inlets, allowing to tune the lasing frequency over a broad spectral range....

  10. Lighting the Way to See Inside Two-Photon Absorption Materials: Structure–Property Relationship and Biological Imaging

    Directory of Open Access Journals (Sweden)

    Qiong Zhang

    2017-02-01

    Full Text Available The application of two-photon absorption (2PA materials is a classical research field and has recently attracted increasing interest. It has generated a demand for new dyes with high 2PA cross-sections. In this short review, we briefly cover the structure-2PA property relationships of organic fluorophores, organic-inorganic nanohybrids and metal complexes explored by our group. (1 The two-photon absorption cross-section (δ of organic fluorophores increases with the extent of charge transfer, which is important to optimize the core, donor-acceptor pair, and conjugation-bridge to obtain a large δ value. Among the various cores, triphenylamine appears to be an efficient core. Lengthening of the conjugation with styryl groups in the D-π-D quadrupoles and D-π-A dipoles increased δ over a long wavelength range than when vinylene groups were used. Large values of δ were observed for extended conjugation length and moderate donor-acceptors in the near-IR wavelengths. The δ value of the three-arm octupole is larger than that of the individual arm, if the core has electron accepting groups that allow significant electronic coupling between the arms; (2 Optical functional organic/inorganic hybrid materials usually show high thermal stability and excellent optical activity; therefore the design of functional organic molecules to build functional organic-inorganic hybrids and optimize the 2PA properties are significant. Advances have been made in the design of organic-inorganic nanohybrid materials of different sizes and shapes for 2PA property, which provide useful examples to illustrate the new features of the 2PA response in comparison to the more thoroughly investigated donor-acceptor based organic compounds and inorganic components; (3 Metal complexes are of particular interest for the design of new materials with large 2PA ability. They offer a wide range of metals with different ligands, which can give rise to tunable electronic and 2PA

  11. Merton and Ziman's modes of science: the case of biological and similar material transfer agreements

    NARCIS (Netherlands)

    Rodriguez, Victor

    2007-01-01

    This paper makes a connection between recent studies on research materials exchange and its effect on the progress of science. Academia fears that scientific development could be hampered by the privatised practices of research material exchange. Since post-academic science represents a sufficient d

  12. Determination of perfluorinated alkyl acid concnetrations in biological standard reference materials

    NARCIS (Netherlands)

    Reiner, J.L.; O'Connell, S.G.; Butt, C.M.; Kwadijk, C.J.A.F.

    2012-01-01

    Standard reference materials (SRMs) are homogeneous, well-characterized materials used to validate measurements and improve the quality of analytical data. The National Institute of Standards and Technology (NIST) has a wide range of SRMs that have mass fraction values assigned for legacy pollutants

  13. Status report on the tunable monochromatic gamma—ray source

    Institute of Scientific and Technical Information of China (English)

    M.Bertschy; W.Mondelaers; 等

    1996-01-01

    The tunable monochromatic gamma-ray source at the Ghent 15MeV linac is described.The characteristics of the monochromatic beam are given,and some applications,as the detection of heavy elements in other materials,are presented.

  14. A New Class of Electrically Tunable Metamaterial Terahertz Modulators

    CERN Document Server

    Yan, Rusen; Liu, Lei; Jena, Debdeep; Xing, Huili Grace

    2012-01-01

    Switchable metamaterials offer unique solutions for efficiently manipulating electromagnetic waves, particularly for terahertz waves, which has been difficult since naturally occurring materials rarely respond to terahertz frequencies controllably. However, few terahertz modulators demonstrated to date exhibit simultaneously low attenuation and high modulation depth. In this letter we propose a new class of electrically-tunable terahertz metamaterial modulators employing metallic frequency-selective-surfaces (FSS) in conjunction with capacitively-tunable layers of electrons, promising near 100% modulation depth and < 15% attenuation. The fundamental departure in our design from the prior art is tuning enabled by self-gated electron layers that is independent from the metallic FSS. Our proposal is applicable to all possible electrically tunable elements including graphene, Si, MoS2, oxides etc, thus opening up myriad opportunities for realizing high performance switchable metamaterials over an ultra-wide te...

  15. [The study of naphthyzin present in material evidence and biological fluids].

    Science.gov (United States)

    Fedorov, D B; Volchenko, S V; Novokshonova, N A; Kuklin, V N

    2013-01-01

    The optimal conditions for isolation of naphazoline from naphthyzin preparations and biological fluids with chloroform at pH 9.18 are described. The compound of interest was identified with the use of color and precipitation reactions, IR and UV spectroscopy, thin-layer and gas chromatography, and chemical methods including high performance liquid chromatography, chromatodensitometry, and UV spectroscopy. The results obtained by the three methods are comparable.

  16. Determination and Certification of Multielements in 6 Biological Reference Materials by NAA

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Food safety has been a problem of global concern. The insufficient availability of certificated reference materials (CRM) used for food analysis has resulted in a lack of internal quality control in food

  17. Microcantilever technology for law enforcement and anti-terrorism applications: chemical, biological, and explosive material detection

    Science.gov (United States)

    Adams, J. D.; Rogers, B.; Whitten, R.

    2005-05-01

    The remarkable sensitivity, compactness, low cost, low power-consumption, scalability, and versatility of microcantilever sensors make this technology among the most promising solutions for detection of chemical and biological agents, as well as explosives. The University of Nevada, Reno, and Nevada Nanotech Systems, Inc (NNTS) are currently developing a microcantilever-based detection system that will measure trace concentrations of explosives, toxic chemicals, and biological agents in air. A baseline sensor unit design that includes the sensor array, electronics, power supply and air handling has been created and preliminary demonstrations of the microcantilever platform have been conducted. The envisioned device would measure about two cubic inches, run on a small watch battery and cost a few hundred dollars. The device could be operated by untrained law enforcement personnel. Microcantilever-based devices could be used to "sniff out" illegal and/or hazardous chemical and biological agents in high traffic public areas, or be packaged as a compact, low-power system used to monitor cargo in shipping containers. Among the best detectors for such applications at present is the dog, an animal which is expensive, requires significant training and can only be made to work for limited time periods. The public is already accustomed to explosives and metal detection systems in airports and other public venues, making the integration of the proposed device into such security protocols straightforward.

  18. EFFECT OF MIXING CONDITIONS ON FLOCCULATION KINETICS OF WASTEWATERS CONTAINING PROTEINS AND OTHER BIOLOGICAL COMPOUNDS USING FIBROUS MATERIALS AND POLYELECTROLYTES

    Directory of Open Access Journals (Sweden)

    L.A. CHEN

    1998-12-01

    Full Text Available The application of a combined system of a polyelectrolyte, carboxymethyl cellulose (CMC, and highly fibrillated fibrous materials, cellulose triacetate fibrets (CTF, for the recovery of proteins and other biological compounds from model and actual biological systems has been demonstrated . In the present work, reaction batches were scaled-up to a one-liter agitated vessel, with a standard configuration. The effect of mixing conditions on the adsorption and flocculation process was studied. It was observed that flocculation time was very fast, occurring within the period of polymer addition. Long term shearing did not result in floc breakage and the values of percentage light transmission and protein concentration of the final filtrate remained the same during the incubation period. Increasing the shear rate resulted in improved process efficiency, up to an optimum value, above which performance was poorer. Perikinetic and orthokinetic rate parameters were calculated and results analyzed in view of these parameters.

  19. Evaluation of Natural Materials as Exogenous Carbon Sources for Biological Treatment of Low Carbon-to-Nitrogen Wastewater

    Science.gov (United States)

    Ramírez-Godínez, Juan; Beltrán-Hernández, Icela; Álvarez-Hernández, Alejandro; Coronel-Olivares, Claudia; Contreras-López, Elizabeth; Quezada-Cruz, Maribel; Vázquez-Rodríguez, Gabriela

    2015-01-01

    In the bacterial processes involved in the mitigation of nitrogen pollution, an adequately high carbon-to-nitrogen (C : N) ratio is key to sustain denitrification. We evaluated three natural materials (woodchips, barley grains, and peanut shells) as carbon sources for low C : N wastewater. The amount of organic matter released from these materials to aqueous media was evaluated, as well as their pollution swapping potential by measuring the release of total Kjeldahl nitrogen, N-NH4+, NO2−, and NO3−, and total phosphorous. Barley grains yielded the highest amount of organic matter, which also showed to be the most easily biodegradable. Woodchips and peanut shells released carbon rather steadily and so they would not require frequent replenishment from biological reactors. These materials produced eluates with lower concentrations of nutrients than the leachates from barley grains. However, as woodchips yielded lower amounts of suspended solids, they constitute an adequate exogenous source for the biological treatment of carbon-deficient effluents. PMID:26495313

  20. Use of vitamin B/sub 12/ radioassay in the analysis of biological materials, mainly of foods

    Energy Technology Data Exchange (ETDEWEB)

    Kralova, B.; Rauch, P.; Cerna, J. (Inst. of Chemical Technology, Prague (Czechoslovakia). Dept. of Biochemistry and Microbiology; Research Inst. of Food Industry, Prague (Czechoslovakia))

    1982-01-01

    Vitamin B/sub 12/ was determined in biological materials by three basically different methods: microbiological assay with Lactobacillus leichmannii, microbiological assay with Escherichia coli and radioassay. The method with E. coli has a relatively low sensitivity to vitamin B/sub 12/ and in some cases of vitamin B/sub 12/ determination in microbial materials it can be used only after a separation of the interfering substances by gel chromatography. The procedure is suitable for orientational determinations of vitamin B/sub 12/ because it is very little affected by external factors. The assay with L. leichmannii is universal owing to its high specifity and sensitivity to vitamin B/sub 12/. The main disadvantage of the latter procedure depends on the high requirements for a clean atmosphere which can be maintained in laboratories in industrial areas only with difficulties. These limitations do not apply to the quick and sensitive radioassay. The radioassay can be used after a suitable adjustment of the working procedure for large series of analyses of biological materials without any preliminary separational techniques.

  1. Tunable perovskite microdisk lasers.

    Science.gov (United States)

    Sun, Wenzhao; Wang, Kaiyang; Gu, Zhiyuan; Xiao, Shumin; Song, Qinghai

    2016-04-28

    Perovskite microdisk lasers have been intensively studied recently. But their lasing properties are usually fixed once the devices are synthesized. Here, for the first time, we demonstrated the switchable and tunable perovskite microdisk lasers by surrounding them with 5CB liquid crystals. With the increase of the environmental temperature from 24 °C to 34 °C, the lasing wavelength slightly changed from 552.91 nm to 552.11 nm at the beginning and suddenly shifted to around 552.54 nm at T = 32 °C, where the phase transition of liquid crystals occurs. Our numerical calculation shows that the wavelength shift is caused by the changes of the refractive index of liquid crystals. More than tuning of the wavelength, a more dramatic wavelength transition from ∼554 nm to 550 nm has also been observed. This sudden transition is mainly induced by the reduction of scattering rather than the change in the refractive index when the liquid crystals are changed from the nematic phase to the isotropic phase. We believe that our research can shed light on the applications of perovskite optoelectronics.

  2. MAK and BAT values list 2013. Maximum permissible concentrations at the place of work and biological tolerance values for working materials; MAK- und BAT-Werte-Liste 2013. Maximale Arbeitsplatzkonzentrationen und Biologische Arbeitsstofftoleranzwerte

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-01

    The book on the MAK (maximum permissible concentrations at the place of work) and BAT (biological tolerance values for working materials) value list 2013 includes the following chapters: (a) Maximum permissible concentrations at the place of work: definition, application and determination of MAT values, list of materials; carcinogenic working materials, sensibilizing working materials, aerosols, limiting the exposition peaks, skin resorption, MAK values during pregnancy, germ cell mutagens, specific working materials; (b) Biological tolerance values for working materials: definition and application of BAT values, list of materials, carcinogenic working materials, biological guide values, biological working material reference values.

  3. MAK and BAT values list 2014. Maximum permissible concentrations at the place of work and biological tolerance values for working materials; MAK- und BAT-Werte-Liste 2014. Maximale Arbeitsplatzkonzentrationen und Biologische Arbeitsstofftoleranzwerte

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-11-01

    The book on the MAK (maximum permissible concentrations at the place of work) and BAT (biological tolerance values for working materials) value list 2014 includes the following chapters: (a) Maximum permissible concentrations at the place of work: definition, application and determination of MAT values, list of materials; carcinogenic working materials, sensibilizing working materials, aerosols, limiting the exposition peaks, skin resorption, MAK values during pregnancy, germ cell mutagens, specific working materials; (b) Biological tolerance values for working materials: definition and application of BAT values, list of materials, carcinogenic working materials, biological guide values, biological working material reference values.

  4. MAK and BAT values list 2015. Maximum permissible concentrations at the place of work and biological tolerance values for working materials; MAK- und BAT-Werte-Liste 2015. Maximale Arbeitsplatzkonzentrationen und Biologische Arbeitsstofftoleranzwerte

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-11-01

    The book on the MAK (maximum permissible concentrations at the place of work) and BAT (biological tolerance values for working materials) value list 2015 includes the following chapters: (a) Maximum permissible concentrations at the place of work: definition, application and determination of MAT values, list of materials; carcinogenic working materials, sensibilizing working materials, aerosols, limiting the exposition peaks, skin resorption, MAK values during pregnancy, germ cell mutagens, specific working materials; (b) Biological tolerance values for working materials: definition and application of BAT values, list of materials, carcinogenic working materials, biological guide values, biological working material reference values.

  5. Biological induced corrosion of materials II: New test methods and experiences from mir station

    Science.gov (United States)

    Klintworth, R.; Reher, H. J.; Viktorov, A. N.; Bohle, D.

    1999-09-01

    During previous long-term manned missions, more than 100 species of microorganisms have been identified on surfaces of materials (bacteria and fungi). Among them were potentially pathogenic ones (saprophytes) which are capable of active growth on artificial substrates, as well as technophilic bacteria and fungi causing damages (destruction and degradation) to various materials (metals and polymers), resulting in failures and disruptions in the functioning of equipment and hardware. Aboard a space vehicle some microclimatic parameters are optimal for microorganism growth: the atmospheric fluid condensate with its specific composition, chemical and/or antropogenic contaminants (human metobolic products, etc.) all are stimulating factors for the development of bacteria and mould fungi on materials of the interior and equipment of an orbital station during its operational phase(s). Especially Russian long-term missions (SALJUT, MIR) have demonstrated that uncontrolled interactions of microorganisms with materials will ultimately lead to the appearence of technological and medical risks, significantly influencing safety and reliability characteristics of individual as well as whole systems and/ or subsystems. For a first conclusion, it could be summarized, that countermeasures and anti-strategies focussing on Microbial Contamination Management (MCM) for the International Space Station (ISS, next long-term manned mission) at least require a new materials test approach. Our respective concept includes a combined age-ing/biocorrosion test sequence. It is represented here, as well as current status of MCM program, e.g. continuous monitoring (microbiological analyses), long-term disinfection, frequent cleaning methods, mathematical modeling of ISS, etc.

  6. Microbiological titration of proteins and of single amino acid content in biological materials without purification and hydrolysis.

    Science.gov (United States)

    Puppo, S; Morpurgo, G; Nardi, S; Conti, G

    1978-04-01

    A method is described for the microbiological determination of the protein content of biological materials. This method can also be adopted to titrate the concentration of a single amino acid in the protein and has the following advantages: (1) titration can be done without purification and hydrolysis of proteins; (2) the titration graph is a straight line between 25 and 800 microgram/ml; (3) protein values agree with those obtained using the Kjeldhal method; and (4) each mutant requiring one amino acid may be used to titrate the concentration of a single amino acid of the protein. The leucine content of various kinds of flour was measured with this system.

  7. Silver nanoparticles with tunable work functions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pangpang, E-mail: pangpang@molecular-device.kyushu-u.ac.jp [Education Center for Global Leaders in Molecular Systems for Devices, Kyushu University, Fukuoka 819-0395 (Japan); Tanaka, Daisuke [Department of Electrical and Electronic Engineering, National Institute of Technology, Oita College, Oita 870-0152 (Japan); Ryuzaki, Sou; Araki, Shohei; Okamoto, Koichi; Tamada, Kaoru [Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-12

    To improve the efficiencies of electronic devices, materials with variable work functions are required to decrease the energy level differences at the interfaces between working layers. Here, we report a method to obtain silver nanoparticles with tunable work functions, which have the same silver core of 5 nm in diameter and are capped by myristates and 1-octanethoilates self-assembled monolayers, respectively. The silver nanoparticles capped by organic molecules can form a uniform two-dimensional sheet at air-water interface, and the sheet can be transferred on various hydrophobic substrates. The surface potential of the two-dimensional nanoparticle sheet was measured in terms of Kelvin probe force microscopy, and the work function of the sheet was then calculated from the surface potential value by comparing with a reference material. The exchange of the capping molecules results in a work function change of approximately 150–250 meV without affecting their hydrophobicity. We systematically discussed the origin of the work function difference and found it should come mainly from the anchor groups of the ligand molecules. The organic molecule capped nanoparticles with tunable work functions have a potential for the applications in organic electronic devices.

  8. Effect of some botanical materials on certain biological aspects of the house fly, Musca domestica L

    Directory of Open Access Journals (Sweden)

    Nabawy A. I. Elkattan, Khalafalla S. Ahmed, Saadya M. Elbermawy and Rabab

    2011-04-01

    Full Text Available The effects of Lantana camara (leaves, Pelargonium zonale (leaves, Cupressus macrocarpa (leaves, Cyperus rotundus (whole plant and Acacia nilotica (seeds powders on some biological aspects of house fly, M. domestica L. were tested. The effects of three lethal concentrations LC25, LC50 and LC75 on the larval duration, pupation percent, pupal weight, pupal duration, adult emergence percent, sex ratio, adult longevity, and fecundity were determined. The induced malformed larvae, pupae and adults were recorded and photographed. The powders of the five plants were found to have promising effects in controlling this insect.

  9. Method for protecting biological material and thermolabile compounds for possible industrial uses

    OpenAIRE

    2015-01-01

    Procedimiento de protección de material biológico en general y sustancias termolábiles, aplicable específicamente a microorganismos y virus y cualquier otro material biológico, así como a cualquier sustancia derivada o no, que necesite protección para alargar su vida útil o ampliar su campo de aplicación, mediante procesado electrohidrodinámico o aerodinámico. Este procesado permite alargar la vida útil del producto de una manera única ya que no conlleva la exposición a temperatura de la ...

  10. Monte Carlo calculations of the energy deposited in biological samples and shielding materials

    Science.gov (United States)

    Akar Tarim, U.; Gurler, O.; Ozmutlu, E. N.; Yalcin, S.

    2014-03-01

    The energy deposited by gamma radiation from the Cs-137 isotope into body tissues (bone and muscle), tissue-like medium (water), and radiation shielding materials (concrete, lead, and water), which is of interest for radiation dosimetry, was obtained using a simple Monte Carlo algorithm. The algorithm also provides a realistic picture of the distribution of backscattered photons from the target and the distribution of photons scattered forward after several scatterings in the scatterer, which is useful in studying radiation shielding. The presented method in this work constitutes an attempt to evaluate the amount of energy absorbed by body tissues and shielding materials.

  11. Functional polyester materials with tunable degradability: Investigations into the use of reductive amination, ketoxime ether, and hydrazone linkages for functionalization, covalent stabilization and crosslinking of poly(epsilon-caprolactone) materials

    Science.gov (United States)

    van Horn, Brooke Angela

    Aliphatic polyesters represent one class of degradable, polymeric materials that is receiving significant attention in the search for, and design of, biocompatible and bioresorbable synthetic substances. Functional and crosslinked polyesters, having potential biomedical value, are the target of many avenues of current research. This dissertation work expands the utility of a specific aliphatic polyester, poly(epsilon-caprolactone-co-2-oxepane-1,5-dione) (P(CL-co-OPD)), which contains backbone ketone units that can be reacted with various functional, nucleophilic agents. Results presented in this dissertation convey both the successes had and the challenges encountered in the employment of different "iminyl" chemistries for the synthesis of functional and crosslinked materials. Specifically, the ketone-functionalized polyester was investigated as a general substrate designed to undergo solution-state intramolecular crosslinking and functionalization upon reductive amination with 1,6-hexanediamine and hexylamine, respectively, in the presence of NaCNBH3. Through detailed analysis of the products from these reactions, and simpler systems including small molecule model compounds, the polymeric gamma-keto ester functionality was determined to be incompatible with the reductive amination chemistry, resulting in chain cleavage via intramolecular lactam formation. Subsequent investigation of ketoxime ether formation using synthetic model hydroxylamines, 1-aminooxydodecane and 1,6-bis(aminooxy)hexane, in solution and in the presence of an acid catalyst, resulted in the targeted graft and crosslinked particulate/gel materials, respectively. With the significant interest in the development of synthetic polymer materials of increasing degrees of complexity, attention has been focused on the efficient and high-yielding conversion of polyesters into multi-functional materials. Facile conjugation of aminooxy- and sulfonyl hydrazide model ligands with P(CL-co-OPD) were also

  12. Development of polydimethylsiloxane substrates with tunable elastic modulus to study cell mechanobiology in muscle and nerve.

    Directory of Open Access Journals (Sweden)

    Rachelle N Palchesko

    Full Text Available Mechanics is an important component in the regulation of cell shape, proliferation, migration and differentiation during normal homeostasis and disease states. Biomaterials that match the elastic modulus of soft tissues have been effective for studying this cell mechanobiology, but improvements are needed in order to investigate a wider range of physicochemical properties in a controlled manner. We hypothesized that polydimethylsiloxane (PDMS blends could be used as the basis of a tunable system where the elastic modulus could be adjusted to match most types of soft tissue. To test this we formulated blends of two commercially available PDMS types, Sylgard 527 and Sylgard 184, which enabled us to fabricate substrates with an elastic modulus anywhere from 5 kPa up to 1.72 MPa. This is a three order-of-magnitude range of tunability, exceeding what is possible with other hydrogel and PDMS systems. Uniquely, the elastic modulus can be controlled independently of other materials properties including surface roughness, surface energy and the ability to functionalize the surface by protein adsorption and microcontact printing. For biological validation, PC12 (neuronal inducible-pheochromocytoma cell line and C2C12 (muscle cell line were used to demonstrate that these PDMS formulations support cell attachment and growth and that these substrates can be used to probe the mechanosensitivity of various cellular processes including neurite extension and muscle differentiation.

  13. Development of polydimethylsiloxane substrates with tunable elastic modulus to study cell mechanobiology in muscle and nerve.

    Science.gov (United States)

    Palchesko, Rachelle N; Zhang, Ling; Sun, Yan; Feinberg, Adam W

    2012-01-01

    Mechanics is an important component in the regulation of cell shape, proliferation, migration and differentiation during normal homeostasis and disease states. Biomaterials that match the elastic modulus of soft tissues have been effective for studying this cell mechanobiology, but improvements are needed in order to investigate a wider range of physicochemical properties in a controlled manner. We hypothesized that polydimethylsiloxane (PDMS) blends could be used as the basis of a tunable system where the elastic modulus could be adjusted to match most types of soft tissue. To test this we formulated blends of two commercially available PDMS types, Sylgard 527 and Sylgard 184, which enabled us to fabricate substrates with an elastic modulus anywhere from 5 kPa up to 1.72 MPa. This is a three order-of-magnitude range of tunability, exceeding what is possible with other hydrogel and PDMS systems. Uniquely, the elastic modulus can be controlled independently of other materials properties including surface roughness, surface energy and the ability to functionalize the surface by protein adsorption and microcontact printing. For biological validation, PC12 (neuronal inducible-pheochromocytoma cell line) and C2C12 (muscle cell line) were used to demonstrate that these PDMS formulations support cell attachment and growth and that these substrates can be used to probe the mechanosensitivity of various cellular processes including neurite extension and muscle differentiation.

  14. Biological testing and chemical analysis of process materials from an integrated two stage coal liquefaction: a status report

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, B.W.; Buhl, P.; Moroni, E.C.

    1983-07-01

    Samples for chemical characterization and biological testing were obtained from ITSL runs 3LCF7, 3LCF8 and 3LCF9. Chemical analysis of these materials showed that SCT products were composed of fewer compounds than analogous materials from Solvent Refined Coal (SRC) processes. Major components in the SCT materials were three-, four-, five- and six-ring neutral polycyclic aromatic hydrocarbons (PAH). Methyl(C/sub 1/) and C/sub 2/ homologs of these compounds were present in relatively low concentrations, compared to their non-alkylated homologs. Organic nitrogen was primarily in the form of tertiary polycyclic aromatic nitrogen heterocycles and carbazoles. Little or no amino PAH (APAH) or cyano PAH were detected in samples taken during normal PDU operations, however, mutagenic APAH were produced during off-normal operation. Microbial mutagenicity appeared to be due mainly to the presence of APAH which were probably formed in the LC finer due to failure of the catalyst to promote deamination following carbon-nitrogen bond scission of nitrogen-containing hydroaromatics. This failure was observed for the off-normal runs where it was likely that the catalyst had been deactivated. Carcinogenic activity of ITSL materials as assessed by (tumors per animal) in the initiation/promotion mouse skin painting assay was slightly reduced for materials produced with good catalyst under normal operation compared to those collected during recycle of the LC Finer feed. Initiation activity of the latter samples did not appear to be significantly different from that of other coal derived materials with comparable boiling ranges. The observed initiation activity was not unexpected, considering analytical data which showed the presence of four-, five- and six-ring PAH in ITSL materials.

  15. Graphene: One Material, Many Possibilities—Application Difficulties in Biological Systems

    Directory of Open Access Journals (Sweden)

    Marta Skoda

    2014-01-01

    Full Text Available Energetic technologies, nanoelectronics, biomedicine including gene therapy, cell imaging or tissue engineering are only few from all possible applications for graphene, the thinnest known carbon configuration and a basic element for other more complicated, better discovered and widely used nanostructures such as graphite, fullerenes and carbon nanotubes. The number of researches concerning graphene applications is rising every day which proves the great interest in its unique structure and properties. Ideal pristine graphene sheet presents a flat membrane of unlimited size with no imperfections while in practice we get different flakes with irregular edges and structural defects which influence the reactivity. Nanomaterials from graphene family differ in size, shape, layer number, lateral dimension, surface chemistry and defect density causing the existence of graphene samples with various influence on biological systems. Whether graphene induces cellular stress and activates apoptosis, or on the contrary facilitates growth and differentiation of the cells depends on its structure, chemical modifications and the growth process. A certain number of in vitro studies has indicated cytotoxic effects of graphene while the other show that it is safe. The diversity of the samples and methods of the production make it impossible to establish clearly the biological impact of graphene.

  16. Graphene-Based Materials as Solid Phase Extraction Sorbent for Trace Metal Ions, Organic Compounds, and Biological Sample Preparation.

    Science.gov (United States)

    Ibrahim, Wan Aini Wan; Nodeh, Hamid Rashidi; Sanagi, Mohd Marsin

    2016-07-03

    Graphene is a new carbon-based material that is of interest in separation science. Graphene has extraordinary properties including nano size, high surface area, thermal and chemical stability, and excellent adsorption affinity to pollutants. Its adsorption mechanisms are through non-covalent interactions (π-π stacking, electrostatic interactions, and H-bonding) for organic compounds and covalent interactions for metal ions. These properties have led to graphene-based material becoming a desirable adsorbent in a popular sample preparation technique known as solid phase extraction (SPE). Numerous studies have been published on graphene applications in recent years, but few review papers have focused on its applications in analytical chemistry. This article focuses on recent preconcentration of trace elements, organic compounds, and biological species using SPE-based graphene, graphene oxide, and their modified forms. Solid phase microextraction and micro SPE (µSPE) methods based on graphene are discussed.

  17. Synthesis of Precision for the Certification of Phosphorus in Biological Materials by INAA

    DEFF Research Database (Denmark)

    Damsgaard, E.; Heydorn, K.

    1987-01-01

    The β-emitter32P was used to determine total phosphorus by INAA in Skim Milk Powder RM 63, a material now certified by the EEC Bureau of Reference (BCR). Samples and comparator were irradiated in the Danish reactor DR 3. One month later the samples were dissolved in water and aliquots counted...

  18. Sustainable Materials Management (SMM) Web Academy Webinar: Compost from Food Waste: Understanding Soil Chemistry and Soil Biology on a College/University Campus

    Science.gov (United States)

    This page contains information about the Sustainable Materials Management (SMM) Web Academy Webinar Series titled Compost from Food Waste:Understanding Soil Chemistry and Soil Biology on a College/University Campus

  19. 2012 best practices for repositories collection, storage, retrieval, and distribution of biological materials for research international society for biological and environmental repositories.

    Science.gov (United States)

    2012-04-01

    Third Edition [Formula: see text] [Box: see text] Printed with permission from the International Society for Biological and Environmental Repositories (ISBER) © 2011 ISBER All Rights Reserved Editor-in-Chief Lori D. Campbell, PhD Associate Editors Fay Betsou, PhD Debra Leiolani Garcia, MPA Judith G. Giri, PhD Karen E. Pitt, PhD Rebecca S. Pugh, MS Katherine C. Sexton, MBA Amy P.N. Skubitz, PhD Stella B. Somiari, PhD Individual Contributors to the Third Edition Jonas Astrin, Susan Baker, Thomas J. Barr, Erica Benson, Mark Cada, Lori Campbell, Antonio Hugo Jose Froes Marques Campos, David Carpentieri, Omoshile Clement, Domenico Coppola, Yvonne De Souza, Paul Fearn, Kelly Feil, Debra Garcia, Judith Giri, William E. Grizzle, Kathleen Groover, Keith Harding, Edward Kaercher, Joseph Kessler, Sarah Loud, Hannah Maynor, Kevin McCluskey, Kevin Meagher, Cheryl Michels, Lisa Miranda, Judy Muller-Cohn, Rolf Muller, James O'Sullivan, Karen Pitt, Rebecca Pugh, Rivka Ravid, Katherine Sexton, Ricardo Luis A. Silva, Frank Simione, Amy Skubitz, Stella Somiari, Frans van der Horst, Gavin Welch, Andy Zaayenga 2012 Best Practices for Repositories: Collection, Storage, Retrieval and Distribution of Biological Materials for Research INTERNATIONAL SOCIETY FOR BIOLOGICAL AND ENVIRONMENTAL REPOSITORIES (ISBER) INTRODUCTION T he availability of high quality biological and environmental specimens for research purposes requires the development of standardized methods for collection, long-term storage, retrieval and distribution of specimens that will enable their future use. Sharing successful strategies for accomplishing this goal is one of the driving forces for the International Society for Biological and Environmental Repositories (ISBER). For more information about ISBER see www.isber.org . ISBER's Best Practices for Repositories (Best Practices) reflect the collective experience of its members and has received broad input from other repository professionals. Throughout this document

  20. Ethical and legal considerations regarding the ownership and commercial use of human biological materials and their derivatives

    Directory of Open Access Journals (Sweden)

    Petrini C

    2012-09-01

    Full Text Available Carlo PetriniItalian National Institute of Health, Rome, ItalyAbstract: This article considers some of the ethical and legal issues relating to the ownership and use – including for commercial purposes – of biological material and products derived from humans. The discussion is divided into three parts: after first examining the general notion of ownership, it moves to the particular case of possible commercial use, and finally reflects on the case in point in the light of the preceding considerations. Units of cord blood donated altruistically for transplantation and which are found unsuitable for storage and transplantation, or which become unsuitable while stored in biobanks, are taken as an example. These cord-blood units can be discarded together with other biological waste, or they can be used for research or the development of blood-derived products such as platelet gel. Several ethical questions (eg, informed consent, property, distribution of profits, and others arise from these circumstances. In this regard, some criteria and limits to use are proposed.Keywords: bioethics, biological specimen banks, cord-blood stem cell transplantation, ethics, informed consent, legislation

  1. Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Sangwon [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS protocols with various alternative assisting materials were developed and applied to many biological systems of interest. Colloidal graphite was used as a matrix for IMS of small molecules for the first time and methodologies for analyses of small metabolites in rat brain tissues, fruits, and plant tissues were developed. With rat brain tissues, the signal enhancement for cerebroside species by colloidal graphite was observed and images of cerebrosides were successfully generated by IMS. In addition, separation of isobaric lipid ions was performed by imaging tandem MS. Directly from Arabidopsis flowers, flavonoids were successfully profiled and heterogeneous distribution of flavonoids in petals was observed for the first time by graphite-assisted LDI(GALDI) IMS.

  2. Social justice and research using human biological material: A response to Mahomed, Nöthling-Slabbert and Pepper.

    Science.gov (United States)

    Jordaan, Donrich W

    2016-06-17

    Social justice in the context of research using human biological material is an important contemporary legal-ethical issue. A question at the heart of this issue is the following: Is it fair to expect a research participant (a person who participates in such research by, among others, making available biological material from his or her body) to participate on an altruistic basis, while the researchers and the investors in the research can gain commercially from the research? In a recent article, Mahomed, Nöthling-Slabbert and Pepper proposed that research participants should be entitled to share in the profits emanating from such research via a proposed new statutory right to the intellectual property emanating from such research. In order to stimulate debate on this important issue of social justice, this article responds to the position of Mahomed et al. by focusing on two main points: Firstly, I contend that Mahomed et al. fail to make a convincing argument in favour of shifting away from altruism; secondly, I caution against framing the debate in terms of the binary poles of altruism v. profitsharing, and suggest that should healthcare public policy ever move away from altruism, various non-monetary forms of benefit-sharing by research participants should be considered.

  3. Modeling and additive manufacturing of bio-inspired composites with tunable fracture mechanical properties.

    Science.gov (United States)

    Dimas, Leon S; Buehler, Markus J

    2014-07-07

    Flaws, imperfections and cracks are ubiquitous in material systems and are commonly the catalysts of catastrophic material failure. As stresses and strains tend to concentrate around cracks and imperfections, structures tend to fail far before large regions of material have ever been subjected to significant loading. Therefore, a major challenge in material design is to engineer systems that perform on par with pristine structures despite the presence of imperfections. In this work we integrate knowledge of biological systems with computational modeling and state of the art additive manufacturing to synthesize advanced composites with tunable fracture mechanical properties. Supported by extensive mesoscale computer simulations, we demonstrate the design and manufacturing of composites that exhibit deformation mechanisms characteristic of pristine systems, featuring flaw-tolerant properties. We analyze the results by directly comparing strain fields for the synthesized composites, obtained through digital image correlation (DIC), and the computationally tested composites. Moreover, we plot Ashby diagrams for the range of simulated and experimental composites. Our findings show good agreement between simulation and experiment, confirming that the proposed mechanisms have a significant potential for vastly improving the fracture response of composite materials. We elucidate the role of stiffness ratio variations of composite constituents as an important feature in determining the composite properties. Moreover, our work validates the predictive ability of our models, presenting them as useful tools for guiding further material design. This work enables the tailored design and manufacturing of composites assembled from inferior building blocks, that obtain optimal combinations of stiffness and toughness.

  4. Ecological evaluation of proposed dredged material from the John F. Baldwin Ship Channel: Phase 3 -- biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, N.P.; Karle, L.M.; Pinza, M.R.; Mayhew, H.L.; White, P.J.; Gruendell, B.D.; Word, J.Q. [Battelle/Marine Sciences Lab., Sequim, WA (United States)

    1993-10-01

    The John F. Baldwin Ship Channel is a 28-mile-long portion of the San Francisco Bay to Stockton Ship Channel, the primary shipping lane through San Francisco Bay and Delta. The San Francisco District of the US Army Corps of Engineers (USACE) is responsible for construction of the John F. Baldwin Ship Channel, which is authorized to be deepened to a project depth of {minus}45 ft relative to mean lower low water (MLLW). Approximately 8.5 million cubic yards (mcy) of sediment will be removed from the channel to reach this project depth. The USACE requested Battelle/Marine Sciences Laboratory (MSL) to conduct testing for ocean disposal under the guidelines in Evaluation of Dredged Material Proposed for Ocean Disposal-Testing Manual (EPA/USACE 1991). This testing manual contains a tiered evaluation approach developed specifically for ocean disposal of dredged material at a selected site. In this study, John F. Baldwin Ship Channel sediments were evaluated under the Tier III (biological) testing guidance, which is considered to be highly stringent and protective of the environment. The Tier III guidance for ocean disposal testing requires tests of water column effects, (following dredged material disposal), deposited sediment toxicity, and bioaccumulation of contaminants from deposited sediment (dredged material).

  5. Bio-Inspired Materials and Devices for Chemical and Biological Defense

    Science.gov (United States)

    2010-09-01

    effectively used in the encapsulation of living cells. Mooney and Augst47 have demonstrated alginate hydrogels as effective scaffolds for osteoblast...spaces that can house functions and be decorated with functional elements hung on the supporting walls and scaffolds . Along with the common silicas and...working with chitosan, pectic acid and alginic acid. Their purpose has been to subsequently react the biopolymers to form new materials which can

  6. Diretrizes nacionais para biorrepositório e biobanco de material biológico humano Brazilian guidelines for biorepositories and biobanks of human biological material

    Directory of Open Access Journals (Sweden)

    Gabriela Marodin

    2013-02-01

    Full Text Available OBJETIVO: Caracterizar a construção participativa e democrática das Diretrizes Nacionais para Biorrepositório e Biobanco de Material Biológico Humano com Finalidade de Pesquisa, baseada nos princípios éticos da dignidade humana, da autonomia, da beneficência, da justiça e da precaução. MÉTODOS: Para a elaboração do documento formou-se um grupo de trabalho interdisciplinar Bioética considerando os seguintes critérios: experiência na operacionalização de biobancos, Biobancos representatividade regional, tipo de material biológico acondicionado e especialistas em Biorrepositório bioética. Participaram, também, membros da Agência Nacional de Vigilância Sanitária Diretrizes - Anvisa, pela competência regulatória e da Comissão Nacional de Ética em Pesquisa - Conep, enquanto controle social. RESULTADOS: O documento, baseado nos preceitos éticos, legais e técnicos, apresenta os conceitos, as atividades, finalidades e diferenças entre biorrepositórios e biobancos, as formas de consentimento do sujeito, além de outros aspectos permeados pela preocupação do uso adequado da informação. As Diretrizes Nacionais para Biorrepositório e Biobanco de Material Biológico Humano com Finalidade de Pesquisa contém 39 artigos, dispostos em cinco capítulos. CONCLUSÃO: A importância de uma regulamentação surge da reflexão ética, considerando a moral, e tendo como norteador os aspectos legais, os quais se traduzem em um documento que não se esgota em si mesmo. A dinamicidade da ciência sempre nos remete à mudança de paradigmas, que podem ir além das legislações existentes.OBJECTIVE: To characterize the participatory and democratic creation of the Brazilian guidelines for biorepositories and biobanks of human biological material with the purpose of research based on the ethical principles of human dignity, autonomy, beneficence, justice, and precaution. METHODS: An interdisciplinary work group was constituted to

  7. Tunable Broadband Printed Carbon Transparent Conductor

    Science.gov (United States)

    Xu, Yue; Wan, Jiayu

    Transparent conductors have been widely applied in solar cells, transparent smart skins, and sensing/imaging antennas, etc. Carbon-based transparent conductor has attracted great attention for its low cost and broad range transparency. Ion intercalation has been known to highly dope graphitic materials, thereby tuning materials' optoelectronic properties. For the first time, we successfully tune the optical transmittance of a reduced graphene oxide (RGO)/CNT network from mid-IR range to visible range by means of Li-ion intercalation/deintercalation. We also observed a simultaneous increase of the electrical conductivity with the Li-ion intercalation. This printed carbon hybrid thin film was prepared through all solution processes and was easily scalable. This study demonstrates the possibility of using ion intercalation for low cost, tunable broadband transparent conductors.

  8. Tunable plasticity in amorphous silicon carbide films.

    Science.gov (United States)

    Matsuda, Yusuke; Kim, Namjun; King, Sean W; Bielefeld, Jeff; Stebbins, Jonathan F; Dauskardt, Reinhold H

    2013-08-28

    Plasticity plays a crucial role in the mechanical behavior of engineering materials. For instance, energy dissipation during plastic deformation is vital to the sufficient fracture resistance of engineering materials. Thus, the lack of plasticity in brittle hybrid organic-inorganic glasses (hybrid glasses) often results in a low fracture resistance and has been a significant challenge for their integration and applications. Here, we demonstrate that hydrogenated amorphous silicon carbide films, a class of hybrid glasses, can exhibit a plasticity that is even tunable by controlling their molecular structure and thereby leads to an increased and adjustable fracture resistance in the films. We decouple the plasticity contribution from the fracture resistance of the films by estimating the "work-of-fracture" using a mean-field approach, which provides some insight into a potential connection between the onset of plasticity in the films and the well-known rigidity percolation threshold.

  9. Tunable on chip optofluidic laser

    DEFF Research Database (Denmark)

    Bakal, Avraham; Vannahme, Christoph; Kristensen, Anders

    2015-01-01

    A chip scale tunable laser in the visible spectral band is realized by generating a periodic droplet array inside a microfluidic channel. Combined with a gain medium within the droplets, the periodic structure provides the optical feedback of the laser. By controlling the pressure applied to two...... separate inlets we can change the period of the droplet array. As a result, the lasing frequency is tuned over a broad spectral range. Using this configuration, we demonstrate wavelength tunability of about 70 nm and lasing threshold of about 15 μJ/mm2....

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

    Directory of Open Access Journals (Sweden)

    Ingi Agnarsson

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

  11. Comparison of three different DNA extraction methods from a highly degraded biological material.

    Science.gov (United States)

    Kuś, M; Ossowski, A; Zielińska, G

    2016-05-01

    The identification of unknown victims is one of the most challenging tasks faced by forensic medicine. This is due to the rapid decomposition of tissues, beginning at the moment of death and caused by released enzymes and microbial activity. Decay is directly associated with the decomposition of soft tissues and also the degradation of genetic material inside cells. Decomposition rates vary depending on a number of environmental factors, including temperature, humidity, season, and soil properties. Decomposition also differs between bodies left in the open air or buried. To date, forensic medicine has identified mainly people who were the victims of various types of criminal offences. However, with advances in identification methods, increasingly frequent attempts are made to identify the victims of armed conflicts, crimes of totalitarian regimes, or genocide. The aim of the study was to compare three different methods for the extraction of nuclear DNA from material considered in forensic medicine as difficult to handle, i.e. fragments of bones and teeth, and to determine the performance of these methods and their suitability for identification procedures.

  12. Natural product isolation--how to get from biological material to pure compounds.

    Science.gov (United States)

    Bucar, Franz; Wube, Abraham; Schmid, Martin

    2013-04-01

    Since the last comprehensive review by Otto Sticher on natural product isolation in NPR (O. Sticher, Nat. Prod. Rep., 2008, 25, 517), a plethora of new reports on isolation of secondary compounds from higher plants, marine organisms and microorganisms has been published. Although methods described earlier like the liquid-solid chromatographic techniques (VLC, FC, MPLC, HPLC) or partition chromatographic methods are still the major tools for isolating pure compounds, some developments like hydrophilic interaction chromatography (HILIC) have not been fully covered in previous reviews. Furthermore, examples of using different preparative solid-phase extraction (SPE) columns including molecular imprinting technology have been included. Special attention is given to chiral stationary phases in isolation of natural products. Methods for proper identification of plant material, problems of post-harvest changes in plant material, extraction methods including application of ionic liquids, de-replication procedures during natural product isolation are further issues to be discussed by the review. Selected work published between 2008 and mid-2012 is covered.

  13. Physico-chemical characterization and biological evaluation of two fibroin materials.

    Science.gov (United States)

    Motta, Antonella; Segnana, Paola; Verin, Lucia; La Monica, Silvia; Fumarola, Claudia; Bucci, Giovanna; Gussago, Francesca; Cantoni, Anna Maria; Ampollini, Luca; Migliaresi, Claudio

    2014-11-01

    Silk fibroin fibres from two different sources, Bombyx mori pure-breed silkworms and polyhybrid cross-bred silkworm cocoons, were treated with formic acid under planar stirring conditions to prepare non-woven nets. The treatment partially dissolved the fibres, which bound together and formed a non-woven micrometric net with fibres coated by a thin layer of low molecular weight fibroin matrix. The starting fibres, net materials and fibroin coating layer were characterized in terms of amino acid composition, molecular weight and calorimetric properties. In vitro cell culture tests with rat fibroblasts were performed to investigate cell proliferation, morphology and spreading. Moreover, host-rat fibroblasts were preseeded on the afore-mentioned nets and implanted in the thorax of rats for histological analysis. In spite of the chemical differences between the two starting fibroins, the response of the said materials in vitro and in vivo were very similar. These results suggest that the outcome is likely correlated with the modification of the processing technique; that during the formation of the net, a thin gel layer of similar amino acid composition was formed on the fibroin fibres.

  14. Feasibility of pressurization to speed up enzymatic hydrolysis of biological materials for multielement determinations.

    Science.gov (United States)

    Moreda-Piñeiro, Antonio; Bermejo-Barrera, Adela; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Muniategui-Lorenzo, Soledad; López-Mahía, Purificación; Prada-Rodríguez, Darío

    2007-03-01

    earth was used as dispersing agent for hydrolyses with either enzyme. Analytical performances, such as limits of detection and quantification and repeatability of the overall procedure, have been established. Finally, accuracy of the methods was assessed by analyzing seafood certified reference materials (GBW-08571, DORM-2, DOLT-3, TORT-2), fatty tissues certified reference materials (BCR 185, NIST 1577b), and fibrous certified reference materials (BCR 62, GBW-08501).

  15. Fractional derivatives in the transport of drugs across biological materials and human skin

    Science.gov (United States)

    Caputo, Michele; Cametti, Cesare

    2016-11-01

    The diffusion of drugs across a composite structure such as a biological membrane is a rather complex phenomenon, because of its inhomogeneous nature, yielding a diffusion rate and a drug solubility strongly dependent on the local position across the membrane itself. These problems are particularly strengthened in composite structures of a considerable thickness like, for example, the human skin, where the high heterogeneity provokes the transport through different simultaneous pathways. In this note, we propose a generalization of the diffusion model based on Fick's 2nd equation by substituting a diffusion constant by means of the memory formalism approach (diffusion with memory). In particular, we employ two different definitions of the fractional derivative, i.e., the usual Caputo fractional derivative and a new definition recently proposed by Caputo and Fabrizio. The model predictions have been compared to experimental results concerning the permeation of two different compounds through human skin in vivo, such as piroxicam, an anti-inflammatory drug, and 4-cyanophenol, a test chemical model compound. Moreover, we have also considered water penetration across human stratum corneum and the diffusion of an antiviral agent employed as model drugs across the skin of male hairless rats. In all cases, a satisfactory good agreement based on the diffusion with memory has been found. However, the model based on the new definition of fractional derivative gives a better description of the experimental data, on the basis of the residuals analysis. The use of the new definition widens the applicability of the fractional derivative to diffusion processes in highly heterogeneous systems.

  16. A novel three-dimensional scaffold for regenerative endodontics: materials and biological characterizations.

    Science.gov (United States)

    Bottino, Marco C; Yassen, Ghaeth H; Platt, Jeffrey A; Labban, Nawaf; Windsor, L Jack; Spolnik, Kenneth J; Bressiani, Ana H A

    2015-11-01

    An electrospun nanocomposite fibrous material holds promise as a scaffold, as well as a drug-delivery device to aid in root maturogenesis and the regeneration of the pulp-dentine complex. A novel three-dimensional (3D) nanocomposite scaffold composed of polydioxanone (PDS II®) and halloysite nanotubes (HNTs) was designed and fabricated by electrospinning. Morphology, structure, mechanical properties and cell compatibility studies were carried out to evaluate the effects of HNTs incorporation (0.5-10 wt% relative to PDS w/w). Overall, a 3D porous network was seen in the different fabricated electrospun scaffolds, regardless of the HNT content. The incorporation of HNTs at 10 wt% led to a significant (p endodontics.

  17. The chewing robot: a new biologically-inspired way to evaluate dental restorative materials.

    Science.gov (United States)

    Raabe, D; Alemzadeh, K; Harrison, A L; Ireland, A J

    2009-01-01

    This paper presents a novel in vitro dental wear simulator based on 6-6 parallel kinematics to replicate mechanical wear formation on dental materials and components, such as individual teeth, crowns or bridges. The human mandible, guided by a range of passive structures moves with up to six degrees of freedom (DOF). Currently available wear simulators lack the ability to perform these complex chewing movements. In addition simulators are unable to replicate the normal range of chewing forces as they have no control system able to mimic the natural muscle function controlled by the human central nervous system. Such discrepancies between true in vivo and simulated in vitro movements will influence the outcome and reliability of wear studies using such approaches. This paper summarizes the development of a new dynamic jaw simulator based on the kinematics of the human jaw.

  18. Behaviors of intercellular materials and nutrients in biological nutrient removal process supplied with domestic wastewater and food waste.

    Science.gov (United States)

    Chae, So-Ryong; Jeong, Hyeong-Seok; Lim, Jae-Lim; Kang, Seok-Tae; Shin, Hang-Sik; Paik, Byeong-Cheon; Youn, Jong-Ho

    2004-01-01

    A four-stage biological nutrient removal (BNR) process was operated to investigate the effect of anaerobically fermented leachate of food waste (AFLFW) as an external carbon source on nutrient removal from domestic wastewater having a low carbon-to-nitrogen ratio. The BNR system that was supplemented with AFLFW showed a good performance at a sludge retention time (SRT) of 30 days, despite low temperature. With this wastewater, average removal efficiencies of soluble chemical oxygen demand (COD), total nitrogen (T-N), and total phosphorus (T-P) were 88 to 93%, 70 to 74%, and 63 to 68%, respectively. In this study, several kinds of poly-hydroxyalkanoates (PHAs) were observed in cells. These included 24% poly-3-hydroxybutyrate (PHB), 41% poly-3-hydroxyvalerate (PHV), 18% poly-3-hydroxyhexanoate (PHH), 10% poly-3-hydroxyoctanoate (PHO), 5% poly-3-hydroxydecanoate (PHD). and 2% poly-3-hydroxydodecanoate (PHDD), indicating that microorganisms could store various PHAs through the different metabolic pathways. However, breakdown of the enhanced biological phosphorus removal (EBPR) mechanism was observed when SRT increased from 30 to 50 days for the enhancement of nitrification. To study the effect of SRT on EBPR, a sequencing batch reactor (SBR) system that was supplied with glucose was operated at various SRTs of 5, 10, and 15 days. Nitrification and denitrification efficiencies increased as SRT increased. However, the content of intracellular materials such as PHAs, glycogen. and poly-P in cells decreased. From these results, it was concluded that SRT should be carefully controlled to increase nitrification activity and to maintain biological phosphorus removal activity in the BNR process.

  19. Biological regeneration of ferric (Fe3+) solution during desulphurisation of gaseous streams: effect of nutrients and support material.

    Science.gov (United States)

    Mulopo, Jean; Schaefer, L

    2015-01-01

    This paper evaluates the biological regeneration of ferric Fe3+ solution during desulphurisation of gaseous streams. Hydrogen sulphide (H2S) is absorbed into aqueous ferric sulphate solution and oxidised to elemental sulphur, while ferric ions Fe3+ are reduced to ferrous ions Fe2+. During the industrial regeneration of Fe3+, nutrients and trace minerals usually provided in a laboratory setup are not present and this depletion of nutrients may have a negative impact on the bacteria responsible for ferrous iron oxidation and may probably affect the oxidation rate. In this study, the effect of nutrients and trace minerals on ferrous iron oxidation have been investigated and the results showed that the presence of nutrients and trace minerals affects the efficiency of bacterial Fe2+oxidation. The scanning electron microscopy analysis of the geotextile support material was also conducted and the results showed that the iron precipitate deposits appear to play a direct role on the bacterial biofilm formation.

  20. Evaluation of some procedures relevant to the determination of trace elemental components in biological materials by destructive neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Berry, D.L.

    1979-01-01

    The development of a simplified procedure for the analysis of biological materials by destructive neutron activation analysis (DNAA) is described. The sample manipulations preceding gamma ray assay were investigated as five specific stages of processing: (1) pre-irradiation treatment; (2) sample irradiation; (3) removal of the organic matrix; (4) removal of interfering radioactivities; and (5) concentration and separation of analyte activities. Each stage was evaluated with respect to susceptibility to sample contamination, loss of trace elemental components, and compatibility with other operations in the overall DNAA procedures. A complete DNAA procedure was proposed and evaluated for the analysis of standard bovine liver and blood samples. The DNAA system was effective for the determination of As, Cu, Fe, Hg, Mo, Rb, Sb, Se, and Zn without yield determinations and with a minimum turn-around time of approximately 3 days.

  1. Ion selective electrode for determination of chloride ion in biological materials, food products, soils and waste water.

    Science.gov (United States)

    Sekerka, I; Lechner, J F

    1978-11-01

    The chloride ion selective electrode is used for a rapid, simple, and reliable determination of chloride ion in biological materials (blood serum, urine, fish, and plant tissues), food products (milk, beef extract, nutrient broth and orange, tomato, and grapefruit juices), soils, and waste water (industrial and municipal). The method consists of treating the samples with perchloric acid (pH 1) and potassium peroxydisulfate and determining the chloride content either by a calibration curve or by known addition or analyte addition, using the chloride ion selective electrode. Such sample treatment eliminates most of the interferences occurring in the samples, including iodide, complexing and reducing compounds, and macromolecular and surface-active species. The method is suitable for a wide range of chloride concentration, e.g., 5010 ppm Cl- in nutrient broth and 4890 ppm in beef extract and as low as 12 and 80 ppm in soil extracts.

  2. Novel optical devices based on the tunable refractive index of magnetic fluid and their characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yong, E-mail: zhaoyong@ise.neu.edu.cn [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhang Yuyan [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Shenyang Institute of Engineering, Shenyang 110136 (China); Lv Riqing; Wang Qi [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2011-12-15

    As a new type of functional material, magnetic fluid (MF) is a stable colloid of magnetic nanoparticles, dressed with surfactant and dispersed in the carrier liquid uniformly. The MF has many unique optical properties, and the most important one is its tunable refractive index property. This paper summarizes the properties of the MF refractive index and the related optical devices. The refractive index can be easily controlled by external magnetic field, temperature, and so on. But the tunable refractive index of MF has a relaxation effect. As a result, the response time is more than milliseconds and the MF is only suitable for low speed environment. Compared with the traditional optical devices, the magnetic fluid based optical devices have the tuning ability. Compared with the tunable optical devices (the electro-optic devices (LiNbO{sub 3}) of more than 10 GHz modulation speed, acoustic-optic devices (Ge) of more than 20 MHz modulation speed), the speed of the magnetic fluid based optical devices is low. Now there are many applications of magnetic fluid based on the refractive index in the field of optical information communication and sensing technology, such as tunable beam splitter, optical-fiber modulator, tunable optical gratings, tunable optical filter, optical logic device, tunable interferometer, and electromagnetic sensor. With the development of the research and application of magnetic fluid,a new method, structure and material to improve the response time can be found, which will play an important role in the fields of optical information communication and sensing technology. - Highlights: > Magnetic fluid is a new type of functional material, which has many unique optical properties. > We summarize the tunable refractive index property and the related optical devices. > Refractive index can be easily controlled by external magnetic field, temperature and so on. > There are many applications in the field of optical communication and sensing technology

  3. Wavelength-Tunable Microlasers Based on the Encapsulation of Organic Dye in Metal-Organic Frameworks.

    Science.gov (United States)

    Wei, Yanhui; Dong, Haiyun; Wei, Cong; Zhang, Wei; Yan, Yongli; Zhao, Yong Sheng

    2016-09-01

    A wavelength-tunable microlaser is realized based on the controlled intramolecular charge transfer (ICT) process in dye-encapsulated metal-organic framework (MOF) material. The confinement effect of the MOFs is beneficial for low-threshold lasing. By effectively controlling the polarity of the MOF pores, the population distribution between the locally excited and ICT states is continuously modulated, thus achieving broadband tunable MOF-based microlasers.

  4. Engineering robust and tunable spatial structures with synthetic gene circuits.

    Science.gov (United States)

    Kong, Wentao; Blanchard, Andrew E; Liao, Chen; Lu, Ting

    2017-01-25

    Controllable spatial patterning is a major goal for the engineering of biological systems. Recently, synthetic gene circuits have become promising tools to achieve the goal; however, they need to possess both functional robustness and tunability in order to facilitate future applications. Here we show that, by harnessing the dual signaling and antibiotic features of nisin, simple synthetic circuits can direct Lactococcus lactis populations to form programmed spatial band-pass structures that do not require fine-tuning and are robust against environmental and cellular context perturbations. Although robust, the patterns are highly tunable, with their band widths specified by the external nisin gradient and cellular nisin immunity. Additionally, the circuits can direct cells to consistently generate designed patterns, even when the gradient is driven by structured nisin-producing bacteria and the patterning cells are composed of multiple species. A mathematical model successfully reproduces all of the observed patterns. Furthermore, the circuits allow us to establish predictable structures of synthetic communities and controllable arrays of cellular stripes and spots in space. This study offers new synthetic biology tools to program spatial structures. It also demonstrates that a deep mining of natural functionalities of living systems is a valuable route to build circuit robustness and tunability.

  5. Comparison between liquid and solid tunable focus lenses

    Energy Technology Data Exchange (ETDEWEB)

    Santiago-Alvarado, A; Cruz-Martinez, V M [Universidad Tecnologica de la Mixteca, Carre. Acatlima Km 2.5 Huajuapan de Leon Oaxaca (Mexico); Vazquez-Montiel, S; Munoz-Lopez, J; Diaz-Gonzalez, G [Instituto Nacional de Astrofisica, Optica y Electronica Luis Enrique Erro 1, Tonantzintla Puebla (Mexico); Campos-Garcia, M, E-mail: santiago@mixteco.utm.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-186, 04510, D.F. Mexico (Mexico)

    2011-01-01

    Nowadays more reports in the use of tunable lenses are reported, it is due to the benefits they offer in optical systems design. A tunable lens is an optical system that can focus on a range of positions by changing dynamically one of its geometric parameters. There are several types of tunable lenses, the most known types are the liquid, the solid elastic, with variable refractive index, and lenses that use a dielectric medium. This paper presents the analysis and opto-mechanical design of two tunable lenses, a liquid lens and another Solid Elastic Lens (SEL). Both lenses are made in mounting aluminium and polydimethylsiloxane (PDMS) as refractor medium, the liquid lens use two elastic membranes containing a liquid medium between them while the SEL only use PDMS material as body of the lens (medium refractor). We describe the opto-mechanical performance of both types of lens highlighting the main features of each. Finally, results of a opto-functional comparison between these prototypes are showed.

  6. Tunable Plasma-Wave Laser Amplifier

    Science.gov (United States)

    Bromage, J.; Haberberger, D.; Davies, A.; Bucht, S.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.

    2016-10-01

    Raman amplification is a process by which a long energetic pump pulse transfers its energy to a counter-propagating short seed pulse through a resonant electron plasma wave. Since its conception, theory and simulations have shown exciting results with up to tens of percent of energy transfer from the pump to the seed pulse. However, experiments have yet to surpass transfer efficiencies of a few percent. A review of past literature shows that largely chirped pump pulses and finite temperature wave breaking could have been the two most detrimental effects. A Raman amplification platform is being developed at the Laboratory for Laser Energetics where a combination of a high-intensity tunable seed laser with sophisticated plasma diagnostics (dynamic Thomson scattering) will make it possible to find the optimal parameter space for high-energy transfer. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  7. Tunable plasmonic lattices of silver nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Andrea; Sinsermsuksakul, Prasert; Yang, Peidong

    2008-02-18

    Silver nanocrystals are ideal building blocks for plasmonicmaterials that exhibit a wide range of unique and potentially usefuloptical phenomena. Individual nanocrystals display distinct opticalscattering spectra and can be assembled into hierarchical structures thatcouple strongly to external electromagnetic fields. This coupling, whichis mediated by surface plasmons, depends on their shape and arrangement.Here we demonstrate the bottom-up assembly of polyhedral silvernanocrystals into macroscopic two-dimensional superlattices using theLangmuir-Blodgett technique. Our ability to control interparticlespacing, density, and packing symmetry allows for tunability of theoptical response over the entire visible range. This assembly strategyoffers a new, practical approach to making novel plasmonic materials forapplication in spectroscopic sensors, sub-wavelength optics, andintegrated devices that utilize field enhancement effects.

  8. Gyroid Nanoporous Membranes with Tunable Permeability

    DEFF Research Database (Denmark)

    Li, Li; Schulte, Lars; Clausen, Lydia D.

    2011-01-01

    Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross......-sided skin membranes, much faster than expected by a naive resistance-in-series model; the flux through the two-sided skin membranes even increases with the membrane thickness. We propose a model that captures the physics behind the observed phenomena, as confirmed by flow visualization experiments...... the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive...

  9. Tunable Magnetic Resonance in Microwave Spintronics Devices

    Science.gov (United States)

    Chen, Yunpeng; Fan, Xin; Xie, Yunsong; Zhou, Yang; Wang, Tao; Wilson, Jeffrey D.; Simons, Rainee N.; Chui, Sui-Tat; Xiao, John Q.

    2015-01-01

    Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe based tunable microwave spintronics devices, which is 10X higher than conventional methods.

  10. Highly stable piezoelectrically tunable optical cavities

    CERN Document Server

    Möhle, Katharina; Döringshoff, Klaus; Nagel, Moritz; Peters, Achim

    2013-01-01

    We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

  11. New Methods of Simulation of Mn(II) EPR Spectra: Single Crystals, Polycrystalline and Amorphous (Biological) Materials

    Science.gov (United States)

    Misra, Sushil K.

    Biological systems exhibit properties of amorphous materials. The Mn(II) ion in amorphous materials is characterized by distributions of spin-Hamiltonian parameters around mean values. It has a certain advantage over other ions, being one of the most abundant elements on the earth. The extent to which living organisms utilize manganese varies from one organism to the other. There is a fairly high concentration of the Mn(II) ion in green plants, which use it in the O2 evolution reaction of photosynthesis (Sauer, 1980). Structure-reactivity relationships in Mn(II)-O2 complexes are given in a review article by Coleman and Taylor (1980). Manganese is a trace requirement in animal nutrition; highly elevated levels of manganese in the diet can be toxic, probably because of an interference with iron homeostasis (Underwood, 1971). On the other hand, animals raised with a dietary deficiency of manganese exhibit severe abnormalities in connective tissue; these problems have been attributed to the obligatory role of Mn(II) in mucopolysaccharide metabolism (Leach, 1971). Mn(II) has been detected unequivocally in living organisms.

  12. Tunable Fermi surface topology and Lifshitz transition in bilayer graphene

    OpenAIRE

    Varlet, Anastasia; Mucha-Kruczyński, Marcin; Bischoff, Dominik; Simonet, Pauline; Taniguchi, Takashi; Watanabe, Kenji; Fal'ko, Vladimir; Ihn, Thomas; Ensslin, Klaus

    2015-01-01

    Bilayer graphene is a highly tunable material: not only can one tune the Fermi energy using standard gates, as in single-layer graphene, but the band structure can also be modified by external perturbations such as transverse electric fields or strain. We review the theoretical basics of the band structure of bilayer graphene and study the evolution of the band structure under the influence of these two external parameters. We highlight their key role concerning the ease to experimentally pro...

  13. Uncooled Tunable LWIR Microbolometer

    Science.gov (United States)

    2010-05-05

    Table.1 Layer structure of the experimental devices in this study. (The optical constants of these materials have been taken from Palik [17...ch. 3, pp. 43-121. [16] H. A. Macleod, Thin Film Optical filters. 3rd ed. Inst of Physics Pub Inc, (2001). [17] E. Palik , Handbook of optical...Collins, Phys. Rev, vol. 101, p. 566, 1956. [65] E. D. Palik , Handbook of Optical Constants of Solids. Elsevier, 1998. [66] D. R. Lide, Ed., CRC

  14. Electromagnetically Tunable Fluids

    Science.gov (United States)

    2011-11-29

    performance of antenna parameters to the fundamental materials properties through multi-scale equivalent circuit representation and modeling One of the...composed of two narrow and orthogonal microstrip patch antennas that behave as printed dipoles. The antenna is fabricated on a Duroid® 5880 substrate (a...flow across them. Fig. 25 – Transmission line model of the antenna shown in Fig. 1. A physical cross-section of the gaps and their circuit model

  15. Fractionally distilled SRC-I, SRC-II, EDS, H-Coal and ITSL direct coal liquefaction process materials: a comparative summary of chemical analysis and biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.W.; Later, D.W.; Dauble, D.D.; Wilson, B.W.

    1985-07-01

    This document reports and compares the results compiled from chemical analyses and biological testing of coal liquefaction process materials which were fractionally distilled, after production, into various comparable boiling-point range cuts. Comparative analyses were performed on solvent refined coal (SRC)-I, SRC-II, H-Coal, EDS an integrated two-stage liquefaction (ITSL) distillate materials. Mutagenicity and carcinogenicity assays were conducted in conjunction with chromatographic and mass spectrometric analyses to provide detailed, comparative, chemical and biological assessments. Where possible, results obtained from the distillate cuts are compared to those from coal liquefaction materials with limited boiling ranges. Work reported here was conducted by investigators in the Biology and Chemistry Department at the Pacific Northwest Laboratory (PNL), Richland, WA. 38 refs., 16 figs., 27 tabs.

  16. Experiments with tunable Josephson metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Butz, Susanne; Jung, Philipp [Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe (Germany); Koshelets, Valery [Kotel' nikov Institute of Radio Engineering and Electronics, RAS, Moscow (Russian Federation); Ustinov, Alexey V. [Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe (Germany); National University of Science and Technology, MISIS, Moscow (Russian Federation)

    2013-07-01

    We report on experiments investigating a tunable metamaterial consisting of rf-SQUIDs. A metamaterial is a medium constructed of artifical elements, so-called meta-atoms, that interact in a specific way with an incoming electromagnetic wave. The size of the individual meta-atom is much smaller than the wavelength. Our metamaterial consists of an array of rf-SQUIDs which is placed into a coplanar waveguide. The rf-SQUIDs couple to the magnetic field component of the propagating microwave. In a frequency range around the resonance frequency, the magnetic permeability μ{sub r} of the metamaterial deviates strongly from the typical value of μ{sub r} = 1. By using an additional constant magnetic field bias, the inductance of the Josephson junction and thereby the resonance frequency of our meta-atom is changed. We show that the magnetic permeability of such a SQUID metamaterial is tunable in situ and compare the experimental results with numerical simulations.

  17. Tunable elastin-mimetic multiblock hybrid copolymers for biomedical applications

    Science.gov (United States)

    Grieshaber, Sarah Elizabeth

    Elastin-mimetic hybrid polymers (EMHPs) have been developed to capture the multiblock molecular architecture of tropoelastin, allowing tunability in chemical, structural, biological, and mechanical properties. Multiblock EMHPs containing flexible synthetic segments were first synthesized via step growth polymerization of diazido-poly(ethylene glycol) (PEG) and alkyne-terminated AKA3KA (K = lysine, A = alanine) (AK2) peptide employing copper (I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC, or orthogonal click chemistry). Covalent crosslinking of the EMHPs with hexamethylene diisocyanate (HMDI) through the lysine residues in the peptide domain afforded an elastomeric hydrogel (xEMHP) with a compressive modulus of 0.12 +/- 0.018 MPa when hydrated. xEMHPs exhibited minimal cytotoxicity to primary porcine vocal fold fibroblasts. The modular nature of the synthesis allowed facile adjustment of the peptide sequence to modulate the structural and the biological properties of EMHPs. Thus, EMHPs containing integrin-binding peptides were constructed using di-azido-PEG and an alkyne-terminated AK2 peptide with a terminal, integrin-binding GRGDSP domain via the step growth click coupling reaction. Hydrogels formed by covalent crosslinking of the RGD-containing EMHPs had a compressive modulus of 1.06 +/- 0.1MPa when hydrated. Neonatal human dermal fibroblasts (NHDFs) were able to adhere to the hydrogels within 1 h, and to spread and develop F-actin filaments 24 h post seeding. NHDF proliferation was only observed on hydrogels containing RGD domains, demonstrating the importance of integrin engagement for cell growth and the potential use of these EMHPs as tissue engineering scaffolds. The tunability of the EMHP system was further investigated by development of self-assembling, pH-responsive multiblock polymers composed of alternating domains of poly(acrylic acid) (PAA) and a peptide derived from the hydrophobic domains of elastin with the sequence (VPGVG)2 (VG2). The

  18. Applications - Some Influences of Engineering Ideas on Biology Being the fifth in a series of essays on the materials of nature

    Institute of Scientific and Technical Information of China (English)

    Julian F. V. Vincent

    2006-01-01

    Ideas from engineering have helped the understanding of biological organisms for thousands of years. However, the mechanical aspects of biological materials and structures can, if properly interpreted and analysed, lead to a deeper understanding of the biology of organisms. Such an approach, although always current in some form, is nevertheless subject to the vagaries of fashion and the availability of analytical techniques. At present we are in a period of upturn. Areas of interest are deployable structures (applications in aerospace), palaeontology (how little do we need to know in order to create a credible biosphere) and food science (we need a rational approach to the mechanics of food).

  19. Focusing Mirror with Tunable Eccentricity

    CERN Document Server

    Stürmer, Moritz; Brunne, Jens; Wallrabe, Ulrike

    2013-01-01

    We present a new kind of varifocal mirror with independently adjustable curvatures in the major directions. For actuation we use two stacked piezo bending actuators with crossed in-plane polarization. This mirror can be used for example as an off-axis focusing device with tunable focal length and compensation for a variable angle of incidence or for coma correction. We demonstrate the prototype of such a mirror and characterize the mechanical deflection, as well as the focusing capabilities.

  20. Heterogeneously grown tunable group-IV laser on silicon

    Science.gov (United States)

    Hudait, Mantu; Clavel, M.; Lester, L.; Saladukha, D.; Ochalski, T.; Murphy-Armando, F.

    2016-02-01

    Tunable tensile-strained germanium (epsilon-Ge) thin films on GaAs and heterogeneously integrated on silicon (Si) have been demonstrated using graded III-V buffer architectures grown by molecular beam epitaxy (MBE). epsilon-Ge epilayers with tunable strain from 0% to 1.95% on GaAs and 0% to 1.11% on Si were realized utilizing MBE. The detailed structural, morphological, band alignment and optical properties of these highly tensile-strained Ge materials were characterized to establish a pathway for wavelength-tunable laser emission from 1.55 μm to 2.1 μm. High-resolution X-ray analysis confirmed pseudomorphic epsilon-Ge epitaxy in which the amount of strain varied linearly as a function of indium alloy composition in the InxGa1-xAs buffer. Cross-sectional transmission electron microscopic analysis demonstrated a sharp heterointerface between the epsilon-Ge and the InxGa1-xAs layer and confirmed the strain state of the epsilon-Ge epilayer. Lowtemperature micro-photoluminescence measurements confirmed both direct and indirect bandgap radiative recombination between the Γ and L valleys of Ge to the light-hole valence band, with L-lh bandgaps of 0.68 eV and 0.65 eV demonstrated for the 0.82% and 1.11% epsilon-Ge on Si, respectively. The highly epsilon-Ge exhibited a direct bandgap, and wavelength-tunable emission was observed for all samples on both GaAs and Si. Successful heterogeneous integration of tunable epsilon-Ge quantum wells on Si paves the way for the implementation of monolithic heterogeneous devices on Si.

  1. Carbon Stable Isotope Analysis of Methylmercury Toxin in Biological Materials by Gas Chromatography Isotope Ratio Mass Spectrometry.

    Science.gov (United States)

    Masbou, Jeremy; Point, David; Guillou, Gaël; Sonke, Jeroen E; Lebreton, Benoit; Richard, Pierre

    2015-12-01

    A critical component of the biogeochemical cycle of mercury (Hg) is the transformation of inorganic Hg to neurotoxic monomethylmercury (CH3Hg). Humans are exposed to CH3Hg by consuming marine fish, yet the origin of CH3Hg in fish is a topic of debate. The carbon stable isotopic composition (δ(13)C) embedded in the methyl group of CH3Hg remains unexplored. This new isotopic information at the molecular level is thought to represent a new proxy to trace the carbon source at the origin of CH3Hg. Here, we present a compound-specific stable isotope analysis (CSIA) technique for the determination of the δ(13)C value of CH3Hg in biological samples by gas chromatography combustion isotope ratio mass spectrometry analysis (GC-C-IRMS). The method consists first of calibrating a CH3Hg standard solution for δ(13)C CSIA. This was achieved by comparing three independent approaches consisting of the derivatization and halogenation of the CH3Hg standard solution. The determination of δ(13)C(CH3Hg) values on natural biological samples was performed by combining a CH3Hg selective extraction, purification, and halogenation followed by GC-C-IRMS analysis. Reference δ(13)C values were established for a tuna fish certified material (ERM-CE464) originating from the Adriatic Sea (δ(13)C(CH3Hg) = -22.1 ± 1.5‰, ± 2 SD). This value is similar to the δ(13)C value of marine algal-derived particulate organic carbon (δ(13)CPOC = -21‰).

  2. Two-stage coal liquefaction process materials from the Wilsonville Facility operated in the nonintegrated and integrated modes: chemical analyses and biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Later, D.W.

    1985-01-01

    This document reports the results from chemical analyses and biological testing of process materials sampled during operation of the Wilsonville Advanced Coal Liquefaction Research and Development Facility (Wilsonville, Alabama) in both the noncoupled or nonintegrated (NTSL Run 241) and coupled or integrated (ITSL Run 242) two-stage liquefaction operating modes. Mutagenicity and carcinogenicity assays were conducted in conjunction with chromatographic and mass spectrometric analyses to provide detailed, comparative chemical and biological assessments of several NTSL and ITSL process materials. In general, the NTSL process materials were biologically more active and chemically more refractory than analogous ITSL process materials. To provide perspective, the NTSL and ITSL results are compared with those from similar testing and analyses of other direct coal liquefaction materials from the solvent refined coal (SRC) I, SRC II and EDS processes. Comparisons are also made between two-stage coal liquefaction materials from the Wilsonville pilot plant and the C.E. Lummus PDU-ITSL Facility in an effort to assess scale-up effects in these two similar processes. 36 references, 26 figures, 37 tables.

  3. Restricted access magnetic materials prepared by dual surface modification for selective extraction of therapeutic drugs from biological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yu; Wang Yuxia; Chen Lei [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China); Wan Qianhong, E-mail: qhwan@tju.edu.cn [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China)

    2012-02-15

    Magnetic porous particles with dual functionality have been prepared by a two-step procedure and evaluated as novel restricted access materials for extraction of therapeutic agents from biological fluids. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic particles with hydrophobic reversed-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate (MTX), leucovorin (LV) and folic acid (FA) relative to bovine serum albumin. While MTX, LV and FA were all bound to the magnetic particles with high affinity, the adsorption of the protein was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, LV and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedure coupled with reversed-phase liquid chromatography analysis was validated in terms of specificity, linearity and reproducibility. The method was shown to be free from interference of endogenous compounds and linear over the concentration range of 0.5-10 {mu}g/mL for the three drugs studied. The limits of detection for the three drugs in serum were in the range of 0.160-0.302 {mu}g/mL. Reproducibility expressed as the RSD of the recovery for ten replicated extractions at three different concentrations was found to be less than 8.93%. With a unique combination of surface functionality with magnetic cores, the restricted access magnetic particles may be adapted in automated and high

  4. Tunable transportable spectroradiometer based on an acousto-optical tunable filter: Development and optical performance

    Science.gov (United States)

    Kozlova, O.; Sadouni, A.; Truong, D.; Briaudeau, S.; Himbert, M.

    2016-12-01

    We describe a high-performance, transportable, versatile spectroradiometer based on an acousto-optical tunable filter (AOTF). The instrument was developed for temperature metrology, namely, to determine the thermodynamic temperature of black bodies above the Ag freezing point (961.78 °C). Its main design feature is the attenuation of the diffraction side lobes (and, thus, out-of-band stray light) thanks to the use of a double-pass configuration. The radiofrequency tuning of the AOTF allows continuous, fine, and rapid wavelength control over a wide spectral range (650 nm-1000 nm). The instrument tunability can be easily calibrated with an Ar spectral lamp with reproducibility within 10 pm over one week. The instrument was characterised in terms of relative signal stability (few 10-4) and wavelength stability (1 pm) over several hours. The spectral responsivity of the instrument was calibrated with two complementary methods: tuning of the wavelength of the optical source or tuning the radiofrequency of the AOTF. Besides the application for thermodynamic temperature determination at the lowest uncertainty level, this instrument can also be used for multispectral non-contact thermometry of processed materials of non-grey and non-unitary emissivity (in the glass or metallurgical industries).

  5. Ultrahigh magnetically responsive microplatelets with tunable fluorescence emission.

    Science.gov (United States)

    Libanori, Rafael; Reusch, Frieder B; Erb, Randall M; Studart, André R

    2013-11-26

    Tuning the optical properties of suspensions by controlling the orientation and spatial distribution of suspended particles with magnetic fields is an interesting approach to creating magnetically controlled displays, microrheology sensors, and materials with tunable light emission. However, the relatively high concentration of magnetic material required to manipulate these particles very often reduces the optical transmittance of the system. In this study, we describe a simple method of generating particles with magnetically tunable optical properties via sol-gel deposition and functionalization of a continuous layer of silica on ultrahigh magnetically responsive (UHMR) alumina microplatelets. UHMR microplatelets with tunable magnetic response in the range of 15-36 G are obtained by the electrostatic adsorption of 2 to 13% of superparamagnetic iron oxide nanoparticles (SPIONs) on the alumina surface. The magnetized platelets are coated with a 20-50 nm layer of SiO2 through the controlled hydrolysis and condensation reactions of tetraethylorthosilicate (TEOS) in an NH3/ethanol mixture. Finally, the silica surface is covalently modified with an organic fluorescent dye by conventional silane chemistry. Because of the anisotropic shape of the particles, control of their orientation and distribution using magnetic fields and field gradients enables easy tuning of the optical properties of the suspension. This strategy allows us to gain both spatial and temporal control over the fluorescence emission from the particle surface, making the multifunctional platelets interesting building blocks for the manipulation of light in colloid-based smart optical devices and sensors.

  6. Tunable nanostructured coating for the capture and selective release of viable circulating tumor cells.

    Science.gov (United States)

    Reátegui, Eduardo; Aceto, Nicola; Lim, Eugene J; Sullivan, James P; Jensen, Anne E; Zeinali, Mahnaz; Martel, Joseph M; Aranyosi, Alexander J; Li, Wei; Castleberry, Steven; Bardia, Aditya; Sequist, Lecia V; Haber, Daniel A; Maheswaran, Shyamala; Hammond, Paula T; Toner, Mehmet; Stott, Shannon L

    2015-03-04

    A layer-by-layer gelatin nanocoating is presented for use as a tunable, dual response biomaterial for the capture and release of circulating tumor cells (CTCs) from cancer patient blood. The entire nanocoating can be dissolved from the surface of microfluidic devices through biologically compatible temperature shifts. Alternatively, individual CTCs can be released through locally applied mechanical stress.

  7. Microelectromechanical Maltese-cross metamaterial with tunable terahertz anisotropy

    Science.gov (United States)

    Zhu, W. M.; Liu, A. Q.; Bourouina, T.; Tsai, D. P.; Teng, J. H.; Zhang, X. H.; Lo, G. Q.; Kwong, D. L.; Zheludev, N. I.

    2012-12-01

    Dichroic polarizers and waveplates exploiting anisotropic materials have vast applications in displays and numerous optical components, such as filters, beamsplitters and isolators. Artificial anisotropic media were recently suggested for the realization of negative refraction, cloaking, hyperlenses, and controlling luminescence. However, extending these applications into the terahertz domain is hampered by a lack of natural anisotropic media, while artificial metamaterials offer a strong engineered anisotropic response. Here we demonstrate a terahertz metamaterial with anisotropy tunable from positive to negative values. It is based on the Maltese-cross pattern, where anisotropy is induced by breaking the four-fold symmetry of the cross by displacing one of its beams. The symmetry breaking permits the excitation of a Fano mode active for one of the polarization eigenstates controlled by actuators using microelectromechanical systems. The metamaterial offers new opportunities for the development of terahertz variable waveplates, tunable filters and polarimetry.

  8. A spectrally tunable plasmonic photosensor with an ultrathin semiconductor region

    CERN Document Server

    Xiao, Shuyuan; Jiang, Xiaoyun; Wang, Boyun; Xu, Chen

    2016-01-01

    Surface plasmon resonance (SPR) has been widely utilized to improve the absorption performance in the photosensors. Graphene has emerged as a promising plasmonic material, which supports tunable SPR and shows significant flexibility over metals. In this letter, a hybrid photosensor based on the integration of periodic cross-shaped graphene arrays with an ultrathin light-absorbing semiconductor is proposed. A tenfold absorption enhancement over a large range of the incidence angle for both light polarizations as well as a considerably high photogeneration rate ($\\sim10^{37}$) is demonstrated at the resonance. Compared with traditional metal-based plasmon-enhanced photosensors, the absorption enhancement here can be expediently tuned with manipulating the Fermi energy of graphene. The proposed photosensor can amplify the photoresponse to the incidence light at the selected wavelength and thus be utilized in photosensing with high efficiency and tunable spectral selectivity in the mid-infrared (mid-IR) and terah...

  9. The Development of Biology Teaching Material Based on the Local Wisdom of Timorese to Improve Students Knowledge and Attitude of Environment in Caring the Preservation of Environment

    Science.gov (United States)

    Ardan, Andam S.

    2016-01-01

    The purposes of this study were (1) to describe the biology learning such as lesson plans, teaching materials, media and worksheets for the tenth grade of High School on the topic of Biodiversity and Basic Classification, Ecosystems and Environment Issues based on local wisdom of Timorese; (2) to analyze the improvement of the environmental…

  10. Dynamic Processes in Biology, Chemistry, and Materials Science: Opportunities for UltraFast Transmission Electron Microscopy - Workshop Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Kabius, Bernd C.; Browning, Nigel D.; Thevuthasan, Suntharampillai; Diehl, Barbara L.; Stach, Eric A.

    2012-07-25

    mission. This workshop built on previous workshops and included three breakout sessions identifying scientific challenges in biology, biogeochemistry, catalysis, and materials science frontier areas of fundamental science that underpin energy and environmental science that would significantly benefit from ultrafast transmission electron microscopy (UTEM). In addition, the current status of time-resolved electron microscopy was examined, and the technologies that will enable future advances in spatio-temporal resolution were identified in a fourth breakout session.

  11. Cellulose nanocrystal and poly[di(ethylene glycol) adipate] blend for tunable lens

    Science.gov (United States)

    Ko, Hyun-U.; Kim, Hyun Chan; Li, Yaguang; Kim, Sang Youn; Kim, Jaehwan

    2016-04-01

    In these days, consumer electronics and medical device for optical diagnosis are minimalized and mobilized. The focusing part is one of crucial parts of optical diagnosis systems to reduce the size and weight. Thus, demand for tunable lens that change the focus itself is increased. To meet the demand, many tunable lens has been studied by utilizing smart materials that responded under mechanical, magnetic, optical, thermal, chemical, electrical or electrochemical stimuli. This paper reports a cellulose nanocrystal (CNC) and poly[di(ethylene glycol) adipate] (PDEGA) blend that is able to respond under electromechanical stimulus. The preparation of CNC/PDEGA and its characterization are illustrated and its actuation behavior is tested . Because the material has high dielectric constant and high reflection index, it is good candidate material for tunable lens.

  12. X-ray lithography and small-angle X-ray scattering: a combination of techniques merging biology and materials science.

    Science.gov (United States)

    Marmiroli, B; Amenitsch, H

    2012-10-01

    The advent of micro/nanotechnology has blurred the border between biology and materials science. Miniaturization of chemical and biological assays, performed by use of micro/nanofluidics, requires both careful selection of the methods of fabrication and the development of materials designed for specific applications. This, in turn, increases the need for interdisciplinary combination of suitable microfabrication and characterisation techniques. In this review, the advantages of combining X-ray lithography, as fabrication technique, with small-angle X-ray scattering measurements will be discussed. X-ray lithography enables the limitations of small-angle X-ray scattering, specifically time resolution and sample environment, to be overcome. Small-angle X-ray scattering, on the other hand, enables investigation and, consequently, adjustment of the nanostructural morphology of microstructures and materials fabricated by X-ray lithography. Moreover, the effect of X-ray irradiation on novel materials can be determined by use of small-angle X-ray scattering. The combination of top-down and bottom-up methods to develop new functional materials and structures with potential in biology will be reported.

  13. Automated extraction of DNA from reference samples from various types of biological materials on the Qiagen BioRobot EZ1 Workstation

    DEFF Research Database (Denmark)

    Stangegaard, Michael; Jørgensen, Mads; Hansen, Anders Johannes

    2009-01-01

    We have validated and implemented a protocol for DNA extraction from various types of biological materials using a Qiagen BioRobot EZ1 Workstation. The sample materials included whole blood, blood from deceased, buccal cells on Omni swabs and FTA Cards, blood on FTA Cards and cotton swabs......, and muscle biopsies. The DNA extraction was validated according to EN/ISO 17025 for the STR kits AmpFlSTR« Identifiler« and AmpFlSTR« Yfiler« (Applied Biosystems). Of 298 samples extracted, 11 (4%) did not yield acceptable results. In conclusion, we have demonstrated that extraction of DNA from various types...... of biological material can be performed quickly and without the use of hazardous chemicals, and that the DNA may be successfully STR typed according to the requirements of forensic genetic investigations accredited according to EN/ISO 17025...

  14. The prevalence of new psychoactive substances in biological material - a three-year review of casework in Poland.

    Science.gov (United States)

    Adamowicz, Piotr; Gieroń, Joanna; Gil, Dominika; Lechowicz, Wojciech; Skulska, Agnieszka; Tokarczyk, Bogdan

    2016-01-01

    New psychoactive substances (NPS) pose a challenge for forensic and clinical toxicologists, as well as for legislators. We present our findings from cases where NPS have been detected in biological material. During the three-year period 2012-2014 we found NPS in 112 cases (out of 1058 analyzed), with 75 cases in 2014 alone. The prevalence of all NPS (15.1-17.6%) was similar to amphetamine alone that was detected in 15.1-16.5% of cases. The new drugs found belonged to the following classes: cathinones (88%), synthetic cannabinoids (5%), phenethylamines (3%), piperazines and piperidines (3%), arylalkylamines (1%) and other (1%). The drugs detected were (in the order of decreased frequency): 3-MMC (50), α-pyrrolidinopentiophenone (α-PVP) (23), pentedrone (16), 3',4'-methylenedioxy-α-pyrrolidinobutyrophenone (MDPBP) (12), synthetic cannabinoid UR-144 (7), ethcathinone (5), mephedrone (5), methylenedioxypyrovalerone (MDPV) (4), 4-methylethcathinone (4-MEC) (3), buphedrone (3), desoxypipradrol (2-DPMP) (3), methylone (2) and 2C-B (2). In single cases, 2-methylmethcathinone (2-MMC), 2C-P, eutylone, 25I-NBOMe, meta-chlorophenylpiperazine (mCPP), ephedrone, methiopropamine (MPA), and 5-(2-aminopropyl)benzofuran (5-APB) were found. One NPS was the sole agent in 35% of all cases, and two or more NPS were present in 19% of cases. NPS (one or more) with other conventional drugs (like amphetamines, cannabinoids, cocaine, and benzodiazepines) were detected in most (65%) of the cases. NPS were very often detected in the blood of drivers which was a challenge for toxicologists due to a lack of data on their influence on psychomotor performance. A review of concentrations showed a wide range of values in different types of cases, especially driving under the influence of drugs (DUID) and intoxication.

  15. A porous silicon thermally tunable optical filter

    Science.gov (United States)

    Song, Da; Tokranova, Natalya; Gracias, Alison; Castracane, James

    2008-02-01

    Porous silicon (PSi) is a promising material for the creation of optical components for chip-to-chip interconnects because of its unique optical properties, flexible fabrication methods and integration with conventional CMOS material sets. In this paper, we present a novel active optical filter made of PSi to select desired optical wavelengths. The tunable membrane type optical filter is based on a Fabry-Perot interferometer employing two Bragg reflectors separated by an adjustable air gap, which can be thermally controlled. The Bragg reflectors contain alternating layers of high and low porosities. These layers were created by electrochemical etching of p+ type silicon wafers by varying the applied current during etching process. Micro bimorph actuators are designed to control the movement of the top DBR mirror, which changes the cavity thickness. By varying the applied current, the proposed filter can tune the transmitted wavelength of the optical signal. Various geometrical shapes and sizes ranging from 100μm to 1mm of the active filtering region have been realized for specific applications. The MOEMS technology-based device fabrication is fully compatible with the existing IC mass fabrication processes, and can be integrated with a variety of active and passive optical components to realize inter-chip or intra-chip communication at the system level at a relatively low cost.

  16. Tunable magnetocaloric effect in transition metal alloys.

    Science.gov (United States)

    Belyea, Dustin D; Lucas, M S; Michel, E; Horwath, J; Miller, Casey W

    2015-10-28

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based "high entropy alloys" in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants.

  17. Tunable magnetocaloric effect in transition metal alloys

    Science.gov (United States)

    Belyea, Dustin D.; Lucas, M. S.; Michel, E.; Horwath, J.; Miller, Casey W.

    2015-10-01

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based “high entropy alloys” in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants.

  18. 可调谐微机电电感(续)%RF MEMS Tunable Inductors (Continued)

    Institute of Scientific and Technical Information of China (English)

    方东明; 张海霞

    2010-01-01

    3 Magnetic Core Tuned Inductor Magnetic core tuned inductor is tuned based on the magneto impedance effect[32].As the bias DC magnetic field is applied along to the axis of the inductor body,the transverse permeability of the soft magnetic layer can be changed to achieve the tunability of the inductance. In order to design tunable microinductors for microwave communication systems,such as the frequency range over 1 GHz,most magnetic materials become non-magnetic,with relative permeability μr=1. These materials are unsuitable for high frequency applications.

  19. Progress of (Sr, Ba) TiO3 ferroelectric thin film and tunability

    Indian Academy of Sciences (India)

    Fu Xinghua; Shan Lianwei; Ding Biyan; Hou Wenping; Fang Zhou; Fu Zhengyi

    2004-10-01

    The fabrication method, technology route and structure performances of (Sr, Ba) TiO3 (SBT) ferroelectric thin film have been summarized in this paper. The tunability of dielectric constant, dielectric loss and leakage current are the basic parameters of tunable microwave devices. The thin films of SBT with high properties could be fabricated by means of RF magnetron sputtering and sol–gel processing. The electrical performances of thin film material can be improved largely by dopants. Some problems are put forward to pay attention to this material research process.

  20. Program biotechnology 2000. Annual report 1990. Biological process engineering, enzyme technology, cell biology, genetic research, plant-breeding, renewable raw materials. Programm Biotechnologie 2000. Jahresbericht 1990. Bioverfahrenstechnik, Enzymtechnologie, Zellbiologie, Genforschung, Pflanzenzuechtung, Nachwachsende Rohstoffe

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    A brief summary of the results of the Federal Government's program biotechnology 2000 and the system of promoting appropriate activities is followed by a detailed survey of funded projects. The main part contains descriptions of the various projects under defined areas of promotion. The material is subdivided into indexes: project number index, syndicate project index, index with names of firms. The publication closes with an organizational chart of the PT BEO (project-administering organization biology, energy, ecology). (UA).

  1. Challenges in Implementing Technology-Rich Curricular High School Biology Materials: First Year Findings from the "Exploring Life" Project.

    Science.gov (United States)

    Price, Betsy; Cates, Ward M.; Bodzin, Alex

    Eighteen high school biology teachers from a stratified sample of 13 distinct geographical United States regions participated in evaluation of the first year prototypes of Exploring Life, a biology program that includes a textbook with an accompanying Internet component and wet-lab investigations. Web activities explain and reinforce the text and…

  2. Colloidal Photonic Crystals Containing Silver Nanoparticles with Tunable Structural Colors

    Directory of Open Access Journals (Sweden)

    Chun-Feng Lai

    2016-05-01

    Full Text Available Polystyrene (PS colloidal photonic crystals (CPhCs containing silver nanoparticles (AgNPs present tunable structural colors. PS CPhC color films containing a high concentration of AgNPs were prepared using self-assembly process through gravitational sedimentation method. High-concentration AgNPs were deposited on the bottom of the substrate and acted as black materials to absorb background and scattering light. Brilliant structural colors were enhanced because of the absorption of incoherent scattering light, and color saturation was increased by the distribution AgNPs on the PS CPhC surfaces. The vivid iridescent structural colors of AgNPs/PS hybrid CPhC films were based on Bragg diffraction and backward scattering absorption using AgNPs. The photonic stop band of PS CPhCs and AgNPs/PS hybrid CPhCs were measured by UV–visible reflection spectrometry and calculated based on the Bragg–Snell law. In addition, the tunable structural colors of AgNPs/PS hybrid CPhC films were evaluated using color measurements according to the Commission International d’Eclairage standard colorimetric system. This paper presents a simple and inexpensive method to produce tunable structural colors for numerous applications, such as textile fabrics, bionic colors, catalysis, and paints.

  3. Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma

    Science.gov (United States)

    Papadopoulos, K.; Zigler, A.

    2006-01-01

    Terahertz (THz) radiation is electromagnetic radiation in the range between several hundred and a few thousand GHz. It covers the gap between fast-wave electronics (millimeter waves) and optics (infrared). This spectral region offers enormous potential for detection of explosives and chemical/biological agents, non-destructive testing of non-metallic structural materials and coatings of aircraft structures, medical imaging, bio-sensing of DNA stretching modes and high-altitude secure communications. The development of these applications has been hindered by the lack of powerful, tunable THz sources with controlled waveform. The need for such sources is accentuated by the strong, but selective absorption of THz radiation during transmission through air with high vapor content. The majority of the current experimental work relies on time-domain spectroscopy using fast electrically biased photoconductive sources in conjunction with femto-second mode-locked Ti:Sapphire lasers. These sources known as Large Aperture Photoconductive Antennas (LAPA) have very limited tunability, relatively low upper bound of power and no bandwidth control. The paper presents a novel source of THz radiation known as Miniature Photoconductive Capacitor Array (MPCA). Experiments demonstrated tunability between .1 - 2 THz, control of the relative bandwidth Δf/f between .5-.01, and controlled pulse length and pulse waveform (temporal shape, chirp, pulse-to-pulse modulation etc.). Direct scaling from the current device indicates efficiency in excess of 30% at 1 THz with 1/f2 scaling at higher frequencies, peak power of 100 kW and average power between .1-1 W. The physics underlying the MPCA is the interaction of a super-luminous ionization front generated by the oblique incidence of a Ti:Sapphire laser pulse on a semiconductor crystal (ZnSe) biased with an alternating electrostatic field, similar to that of a frozen wave generator. It is shown theoretically and experimentally that the

  4. Biological conversion system

    Science.gov (United States)

    Scott, C.D.

    A system for bioconversion of organic material comprises a primary bioreactor column wherein a biological active agent (zymomonas mobilis) converts the organic material (sugar) to a product (alcohol), a rejuvenator column wherein the biological activity of said biological active agent is enhanced, and means for circulating said biological active agent between said primary bioreactor column and said rejuvenator column.

  5. Optical performance of a PDMS tunable lens with automatically controlled applied stress

    Science.gov (United States)

    Cruz-Felix, Angel S.; Santiago-Alvarado, Agustín.; Hernández-Méndez, Arturo; Reyes-Pérez, Emilio R.; Tepichín-Rodriguez, Eduardo

    2016-09-01

    The advances in the field of adaptive optics and in the fabrication of tunable optical components capable to automatically modify their physical features are of great interest in areas like machine vision, imaging systems, ophthalmology, etc. Such components like tunable lenses are used to reduce the overall size of optical setups like in small camera systems and even to imitate some biological functions made by the human eye. In this direction, in the last years we have been working in the development and fabrication of PDMS-made tunable lenses and in the design of special mechanical mounting systems to manipulate them. A PDMS-made tunable lens was previously designed by us, following the scheme reported by Navarro et al. in 1985, in order to mimic the accommodation process made by the crystalline lens of the human eye. The design included a simulation of the application of radial stress onto the lens and it was shown that the effective focal length was indeed changed. In this work we show the fabrication process of this particular tunable lens and an optimized mechanism that is able to automatically change the curvature of both surfaces of the lens by the application of controlled stress. We also show results of a study and analysis of aberrations performed to the Solid Elastic Lens (SEL).

  6. Engineering the cell-semiconductor interface: a materials modification approach using II-VI and III-V semiconductor materials.

    Science.gov (United States)

    Bain, Lauren E; Ivanisevic, Albena

    2015-02-18

    Developing functional biomedical devices based on semiconductor materials requires an understanding of interactions taking place at the material-biosystem interface. Cell behavior is dependent on the local physicochemical environment. While standard routes of material preparation involve chemical functionalization of the active surface, this review emphasizes both biocompatibility of unmodified surfaces as well as use of topographic features in manipulating cell-material interactions. Initially, the review discusses experiments involving unmodified II-VI and III-V semiconductors - a starting point for assessing cytotoxicity and biocompatibility - followed by specific surface modification, including the generation of submicron roughness or the potential effect of quantum dot structures. Finally, the discussion turns to more recent work in coupling topography and specific chemistry, enhancing the tunability of the cell-semiconductor interface. With this broadened materials approach, researchers' ability to tune the interactions between semiconductors and biological environments continues to improve, reaching new heights in device function.

  7. Immobilization of Enzymes in Nanoporous Host Materials: A Nanobiotechnological Approach to Decontamination and Demilitarization of Chemical and Biological Warfare Agents

    Science.gov (United States)

    2007-11-02

    Type IV with H2 hysteresis loop, typical of mesoporous materials. The incorporation of the methyl group into the silica matrix (OPAA-HF series samples...compared to that of the immobilized enzymes in TMOS-derived materials. The non-surfactant template pathway58-59 to the mesoporous silica materials...biocatalyst OPAA into mesoporous silica host materials of various compositions. OPAA was chosen owing to its ability to catalyze the hydrolysis of highly

  8. Determination of nickel in biological materials after microwave dissolution using inductively coupled plasma atomic emission spectrometry with prior extraction into butan-1-ol.

    Science.gov (United States)

    Vereda Alonso, E; García de Torres, A; Cano Pavón, J M

    1992-07-01

    A sensitive procedure has been developed for the determination of ultratrace amounts of nickel in biological materials by inductively coupled plasma atomic emission spectrometry after extraction of the nickel ion into butan-1-ol by using 1,5-bis(di-2-pyridylmethylene)thiocarbonohydrazide as the extracting reagent. Fast, efficient and complete sample digestion is achieved by an HNO3-HCl poly(tetrafluoroethylene) bomb dissolution technique using microwave heating. Results obtained for eleven certified reference materials agreed with the certified values.

  9. Application of direct solid sample analysis for the determination of chlorine in biological materials using electrothermal vaporization inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Santos de Gois, Jefferson; Pereira, Éderson R. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC (Brazil); Welz, Bernhard [Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC (Brazil); INCT de Energia e Ambiente do CNPq (Brazil); Borges, Daniel L.G., E-mail: daniel.borges@ufsc.br [Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC (Brazil); INCT de Energia e Ambiente do CNPq (Brazil)

    2015-03-01

    This work describes a methodology developed to carry out Cl determination in biological materials using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis. The solid samples were directly weighed into graphite ‘cups’ and inserted into the graphite furnace. The RF power and the carrier gas flow rate were optimized at 1300 W and 0.7 L min{sup −1}, respectively. Calibration could be carried out using aqueous standard solutions with pre-dried modifiers (Pd + Nd or Pd + Ca) or using solid certified reference materials with the same pre-dried modifiers or without the use of modifiers. The limit of quantification was determined as 5 μg g{sup −1} under optimized conditions and the Cl concentration was determined in five certified reference materials with certified concentrations for Cl, in addition to three certified reference materials, for which certified values for Cl were unavailable; in the latter case, the results were compared with those obtained using high-resolution continuum source molecular absorption spectrometry. Good agreement at a 95% statistical confidence level was achieved between determined and certified or reference values. - Highlights: • Direct determination of chlorine in solid biological materials is described for the first time using ICP-MS. • Calibration against aqueous standards is feasible. • The method is accurate and sensitive, regardless of the composition of the solid sample.

  10. Tunable nanostructures as photothermal theranostic agents.

    Science.gov (United States)

    Young, Joseph K; Figueroa, Elizabeth R; Drezek, Rebekah A

    2012-02-01

    The theranostic potential of several nanostructures has been discussed in the context of photothermal therapies and imaging. In the last several decades, the burden of cancer has grown rapidly, making the need for new theranostic approaches vital. Lasers have emerged as promising tools in cancer treatment, especially with the advent of photothermal therapies wherein light absorbing dyes or plasmonic gold nanoparticles are used to generate heat and achieve tumor damage. Recently, photoabsorbing nanostructures have materialized that can be employed in conjunction with lasers in the near-infrared region in order to enhance both imaging and photothermal effects. The incorporation of tunable nanostructures has resulted in improved specificity in cancer treatment. Silica-cored gold nanoshells and gold nanorods currently serve as the chief plasmonic structures for photothermal therapy. Although gold nanorods and silica-cored gold nanoshells have shown promise as therapeutic agents, over the past few years new nanostructures have emerged that offer comparable and even superior theranostic properties. In the present review, several theranostic agents and their impact on the development of more effective photothermal therapies for the treatment of cancer are discussed. These agents include hollow gold nanoshells, gold gold-sulfide nanoparticles, gold nanocages, carbon and titanium nanotubes, photothermal-based nanobubbles, polymeric nanoparticles and copper-based nanocrystals.

  11. Patchy polymer colloids with tunable anisotropy dimensions.

    Science.gov (United States)

    Kraft, Daniela J; Hilhorst, Jan; Heinen, Maria A P; Hoogenraad, Mathijs J; Luigjes, Bob; Kegel, Willem K

    2011-06-09

    We present the synthesis of polymer colloids with continuously tunable anisotropy dimensions: patchiness, roughness, and branching. Our method makes use of controlled fusion of multiple protrusions on highly cross-linked polymer particles produced by seeded emulsion polymerization. Carefully changing the synthesis conditions, we can tune the number of protrusions, or branching, of the obtained particles from spheres with one to three patches to raspberry-like particles with multiple protrusions. In addition to that, roughness is generated on the seed particles by adsorption of secondary nucleated particles during synthesis. The size of the roughness relative to the smooth patches can be continuously tuned by the initiator, surfactant, and styrene concentrations. Seed colloids chemically different from the protrusions induce patches of different chemical nature. The underlying generality of the synthesis procedure allows for application to a variety of seed particle sizes and materials. We demonstrate the use of differently sized polyNIPAM (poly-N-isopropylacrylamide), as well as polystyrene and magnetite filled polyNIPAM seed particles, the latter giving rise to magnetically anisotropic colloids. The high yield together with the uniform, anisotropic shape make them interesting candidates for use as smart building blocks in self-assembling systems.

  12. Shape-tunable core-shell microparticles.

    Science.gov (United States)

    Klein, Matthias K; Saenger, Nicolai R; Schuetter, Stefan; Pfleiderer, Patrick; Zumbusch, Andreas

    2014-10-28

    Colloidal polymer particles are an important class of materials finding use in both everyday and basic research applications. Tailoring their composition, shape, and functionality is of key importance. In this article, we describe a new class of shape-tunable core-shell microparticles. They are composed of a cross-linked polystyrene (PS) core and a poly(methyl methacrylate) (PMMA) shell of varying thickness. In the first step, we prepared highly cross-linked PS cores, which are subsequently transferred into a nonpolar dispersant. They serve as the seed dispersion for a nonaqueous dispersion polymerization to generate the PMMA shell. The shape of the particles can subsequently be manipulated. After the shell growth stage, the spherical PS/PMMA core-shell colloids exhibit an uneven and wrinkled surface. An additional tempering procedure allows for smoothing the surface of the core-shell colloids. This results in polymer core-shell particles with a perfectly spherical shape. In addition to this thermal smoothing of the PMMA shell, we generated a selection of shape-anisotropic core-shell particles using a thermomechanical stretching procedure. Because of the unique constitution, we can selectively interrogate molecular vibrations in the PS core or the PMMA shell of the colloids using nonlinear optical microscopy techniques. This is of great interest because no photobleaching occurs, such that the particles can be tracked in real space over long times.

  13. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron;

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  14. Tunable Beam Diffraction in Infiltrated Microstructured Fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.;

    We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites....

  15. Tunable beam steering enabled by graphene metamaterials.

    Science.gov (United States)

    Orazbayev, B; Beruete, M; Khromova, I

    2016-04-18

    We demonstrate tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. The effective refractive index of such metamaterials can be manipulated by changing the chemical potential of each graphene layer. This can arbitrarily tailor the spatial distribution of the phase of the transmitted beam, providing mechanisms for active beam steering. Three different beam steerer (BS) designs are discussed: a graded-index (GRIN) graphene-based metamaterial block, an array of metallic waveguides filled with graphene-dielectric metamaterial and an array of planar waveguides created in a graphene-dielectric metamaterial block with a specific spatial profile of graphene sheets doping. The performances of the BSs are numerically analyzed, showing the tunability of the proposed designs for a wide range of output angles (up to approximately 70°). The proposed graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.

  16. Electro-Optic Tunable Laser Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop a compact, rugged, rapidly and widely tunable laser based on a quantum cascade diode laser at...

  17. The Berkeley tunable far infrared laser spectrometers

    Science.gov (United States)

    Blake, G. A.; Laughlin, K. B.; Cohen, R. C.; Busarow, K. L.; Gwo, D.-H.

    1991-01-01

    A detailed description is presented for a tunable far infrared laser spectrometer based on frequency mixing of an optically pumped molecular gas laser with tunable microwave radiation in a Schottky point contact diode. The system has been operated on over 30 laser lines in the range 10-100/cm and exhibits a maximum absorption sensitivity near one part in a million. Each laser line can be tuned by + or - 110 GHz with first-order sidebands.

  18. Tunability of Nonuniform Reflection Holographic Filter

    Institute of Scientific and Technical Information of China (English)

    Shanhong You(游善红); Xinwan Li(李新碗); Jianhong Wu(吴建宏); Zongmin Yin(殷宗敏); Minxue Tang(唐敏学)

    2003-01-01

    The tunability of nonuniform reflection holographic filter is investigated theoretically and experimentally. It is shown that the reflection holographic filter has not only high optical density and narrow bandwidth, but also good tunability. The coupled wave theoretical model for uniform medium is compared with the model for nonuniform medium. It is identified that the coincidence of the theoretical results of the nonuniform model with the experimental results are better than that of the uniform model.

  19. Tunable spectral enhancement of fiber supercontinuum

    Science.gov (United States)

    Yeom, Dong-Il; Bolger, Jeremy A.; Marshall, Graham D.; Austin, Dane R.; Kuhlmey, Boris T.; Withford, Michael J.; de Sterke, C. Martijn; Eggleton, Benjamin J.

    2007-06-01

    We demonstrate tunable spectral enhancement of the supercontinuum generated in a microstructured fiber with a fiber long-period grating. The long-period grating leads to phase distortion and loss that, with subsequent high-intensity propagation in uniform fiber, evolves into an enhancement around the grating's resonant wavelengths. Wavelength tunability is achieved by varying the temperature or the ambient refractive index, and the spectral peak can be extinguished by immersing the grating in index-matching oil.

  20. Quantum rainbow scattering at tunable velocities

    CERN Document Server

    Strebel, M; Ruff, B; Stienkemeier, F; Mudrich, M

    2012-01-01

    Elastic scattering cross sections are measured for lithium atoms colliding with rare gas atoms and SF6 molecules at tunable relative velocities down to ~50 m/s. Our scattering apparatus combines a velocity-tunable molecular beam with a magneto-optic trap that provides an ultracold cloud of lithium atoms as a scattering target. Comparison with theory reveals the quantum nature of the collision dynamics in the studied regime, including both rainbows as well as orbiting resonances.

  1. Electrically Tunable Plasmonic Resonances with Graphene

    DEFF Research Database (Denmark)

    Emani, Naresh K.; Chung, Ting-Fung; Ni, Xingjie

    2012-01-01

    Real time switching of a plasmonic resonance may find numerous applications in subwavelength optoelectronics, spectroscopy and sensing. We take advantage of electrically tunable interband transitions in graphene to control the strength of the plasmonic resonance.......Real time switching of a plasmonic resonance may find numerous applications in subwavelength optoelectronics, spectroscopy and sensing. We take advantage of electrically tunable interband transitions in graphene to control the strength of the plasmonic resonance....

  2. The acquisition of dangerous biological materials: Technical facts sheets to assist risk assessments of 46 potential BW agents

    Energy Technology Data Exchange (ETDEWEB)

    Aceto, Donato Gonzalo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Astuto-Gribble, Lisa M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gaudioso, Jennifer M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2007-11-01

    Numerous terrorist organizations have openly expressed interest in producing and deploying biological weapons. However, a limiting factor for many terrorists has been the acquisition of dangerous biological agents, as evidenced by the very few successful instances of biological weapons use compared to the number of documented hoaxes. Biological agents vary greatly in their ability to cause loss of life and economic damage. Some agents, if released properly, can kill many people and cause an extensive number of secondary infections; other agents will sicken only a small number of people for a short period of time. Consequently, several biological agents can potentially be used to perpetrate a bioterrorism attack but few are likely capable of causing a high consequence event. It is crucial, from a US national security perspective, to more deeply understand the likelihood that terrorist organizations can acquire the range of these agents. Few studies have attempted to comprehensively compile the technical information directly relevant to the acquisition of dangerous bacteria, viruses and toxins. In this report, technical fact sheets were assembled for 46 potentially dangerous biological agents. Much of the information was taken from various research sources which could ultimately and significantly expedite and improve bioterrorism threat assessments. By systematically examining a number of specific agent characteristics included in these fact sheets, it may be possible to detect, target, and implement measures to thwart future terrorist acquisition attempts. In addition, the information in these fact sheets may be used as a tool to help laboratories gain a rudimentary understanding of how attractive a method laboratory theft is relative to other potential acquisition modes.

  3. Tunable defect modes in 2D photonic crystals by means of external magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Soltani Vala, A., E-mail: asoltani@tabrizu.ac.i [Physics Department, University of Tabriz, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Rezaei, B. [Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of); Kalafi, M. [Physics Department, University of Tabriz, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2010-07-15

    We investigate the tunable defect modes in 2D photonic crystal of silicon rods in air background in which one of the rods is replaced by ferrite material and an external static magnetic field is applied in the ferrite rod direction. Using the supercell method, the dependence of E-polarized defect modes on the magnetic field has been reported.

  4. Surface brightens up Si quantum dots: direct bandgap-like size-tunable emission

    NARCIS (Netherlands)

    Dohnalova, K.; Poddubny, A.N.; Prokofiev, A.A.; Dam-de Boer, W.; Umesh, C.P.; Paulusse, J.M.J.; Zuilhof, H.; Gregorkiewicz, T.

    2013-01-01

    Colloidal semiconductor quantum dots (QDs) constitute a perfect material for ink-jet printable large area displays, photovoltaics, light-emitting diode, bio-imaging luminescent markers and many other applications. For this purpose, efficient light emission/absorption and spectral tunability are nece

  5. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Science.gov (United States)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2009-12-29

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  6. Thermo-tunable hybrid photonic crystal fiber based on solution-processed chalcogenide glass nanolayers

    DEFF Research Database (Denmark)

    Markos, Christos

    2016-01-01

    The possibility to combine silica photonic crystal fiber (PCF) as low-loss platform with advanced functional materials, offers an enormous range of choices for the development of fiber-based tunable devices. Here, we report a tunable hybrid silica PCF with integrated As2S3 glass nanolayers inside...... antiresonances by taking advantage the high thermo-optic coefficient of the solution-processed nanolayers. Two different hybrid fiber structures, with core diameter 10 and 5 mu m, were developed and characterized using a supercontinuum source. The maximum sensitivity was measured to be as high as 3.6 nm...

  7. Chiral front propagation in liquid-crystalline materials: Formation of the planar monodomain twisted plywood architecture of biological fibrous composites.

    Science.gov (United States)

    De Luca, Gino; Rey, Alejandro D

    2004-01-01

    Biological fibrous composites commonly exhibit an architecture known as twisted plywood, which is similar to that of the cholesteric liquid-crystalline mesophases. The explanation for the structural similarity is that biological fibrous composites adopt a lyotropic cholesteric liquid-crystalline phase during their formation process. In this work, a mathematical model based on the Landau-de Gennes theory of liquid crystals has been developed to reproduce the process by which long chiral fibrous molecules form the twisted plywood structures observed in biological composites. The dynamics of the process was then further investigated by analytically solving a simplified version of the governing equations. Results obtained from the model are in good qualitative agreement with the theory of Neville [Biology of Fibrous Composites (Cambridge University Press, Cambridge, England, 1993)] who hypothesized the necessity of a constraining layer to lock the direction of the helical axis of the plywood in order to create a monodomain structure. Computational results indicate that the plywood architecture is obtained by a chiral front propagation process with a fully relaxed wake. The effects of chirality and concentration on the formation process kinetics are characterized.

  8. Tunable-Bandwidth Filter System

    Science.gov (United States)

    Aye, Tin; Yu, Kevin; Dimov, Fedor; Savant, Gajendra

    2006-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote-sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS was shown to be capable of spectral sampling of images in the visible range over a 200-nm spectral range with a spectral resolution of .30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of the lenses are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses

  9. Using clickers in nonmajors- and majors-level biology courses: student opinion, learning, and long-term retention of course material.

    Science.gov (United States)

    Crossgrove, Kirsten; Curran, Kristen L

    2008-01-01

    Student response systems (clickers) are viewed positively by students and instructors in numerous studies. Evidence that clickers enhance student learning is more variable. After becoming comfortable with the technology during fall 2005-spring 2006, we compared student opinion and student achievement in two different courses taught with clickers in fall 2006. One course was an introductory biology class for nonmajors, and the other course was a 200 level genetics class for biology majors. Students in both courses had positive opinions of the clickers, although we observed some interesting differences between the two groups of students. Student performance was significantly higher on exam questions covering material taught with clickers, although the differences were more dramatic for the nonmajors biology course than the genetics course. We also compared retention of information 4 mo after the course ended, and we saw increased retention of material taught with clickers for the nonmajors course, but not for the genetics course. We discuss the implications of our results in light of differences in how the two courses were taught and differences between science majors and nonmajors.

  10. Continuously Tunable Wettability by Using Surface Patterned Shape Memory Polymers with Giant Deformability.

    Science.gov (United States)

    Zhao, Lingyu; Zhao, Jun; Liu, Yayun; Guo, Yufeng; Zhang, Liangpei; Chen, Zhuo; Zhang, Hui; Zhang, Zhong

    2016-06-01

    Designing smart surfaces with tunable wettability has drawn much attention in recent years for academic research and practical applications. Most of the previous methods to achieve such surfaces demand some particular materials that inherently have special features or complicated structures which are usually not easy to obtain. A novel strategy to achieve such smart surfaces is proposed by using the surface patterned shape memory polymers of chemically crosslinked polycyclooctene which shows a giant deformability of up to ≈730% strain. The smart surfaces possess the ability to continuously tune the wettability by controlling the recovery temperature and/or time. Coating the modified titanium dioxide nanoparticles onto such surfaces renders the surface superhydrophobicity and expands the tunable range of contact angles (CAs). Theoretical calculations of the CAs at different strains via modified Cassie model well explain the tunable wettability behaviors of such smart surfaces.

  11. Highly tunable piezocaloric effect in antiferroelectric PbZrO3

    Science.gov (United States)

    Lisenkov, S.; Mani, B. K.; Cuozzo, J.; Ponomareva, I.

    2016-02-01

    A first-principles-based effective Hamiltonian approach is used to predict the existence of a highly tunable piezocaloric effect in antiferroelectric PbZrO3. The high tunability originates from a strong dependence of both the magnitude and sign of the piezocaloric temperature change on the initial temperature and the nature of the stress. The linearity of the temperature response to the applied stress allows for the doubling of the efficiency of the basic solid state refrigeration cycle. The large values and high tunability of the piezocaloric effect in antiferroelectrics is traced to the strong coupling between the multiple order parameters that coexist in such materials. An experimental setup for the demonstration of such an unusual effect is proposed.

  12. Tunable terahertz fishnet metamaterials based on thin nematic liquid crystal layers for fast switching.

    Science.gov (United States)

    Zografopoulos, Dimitrios C; Beccherelli, Romeo

    2015-08-14

    The electrically tunable properties of liquid-crystal fishnet metamaterials are theoretically investigated in the terahertz spectrum. A nematic liquid crystal layer is introduced between two fishnet metallic structures, forming a voltage-controlled metamaterial cavity. Tuning of the nematic molecular orientation is shown to shift the magnetic resonance frequency of the metamaterial and its overall electromagnetic response. A shift higher than 150 GHz is predicted for common dielectric and liquid crystalline materials used in terahertz technology and for low applied voltage values. Owing to the few micron-thick liquid crystal cell, the response speed of the tunable metamaterial is calculated as orders of magnitude faster than in demonstrated liquid-crystal based non-resonant terahertz components. Such tunable metamaterial elements are proposed for the advanced control of electromagnetic wave propagation in terahertz applications.

  13. Mesoporous Silicas with Tunable Morphology for the Immobilization of Laccase

    Directory of Open Access Journals (Sweden)

    Victoria Gascón

    2014-05-01

    Full Text Available Siliceous ordered mesoporous materials (OMM are gaining interest as supports for enzyme immobilization due to their uniform pore size, large surface area, tunable pore network and the introduction of organic components to mesoporous structure. We used SBA-15 type silica materials, which exhibit a regular 2D hexagonal packing of cylindrical mesopores of uniform size, for non-covalent immobilization of laccase. Synthesis conditions were adjusted in order to obtain supports with different particle shape, where those with shorter channels had higher loading capacity. Despite the similar isoelectric points of silica and laccase and the close match between the size of laccase and the pore dimensions of these SBA-15 materials, immobilization was achieved with very low leaching. Surface modification of macro-/mesoporous amorphous silica by grafting of amine moieties was proved to significantly increase the isoelectric point of this support and improve the immobilization yield.

  14. Band gap tunability of magneto-elastic phononic crystal

    Science.gov (United States)

    Bou Matar, O.; Robillard, J. F.; Vasseur, J. O.; Hladky-Hennion, A.-C.; Deymier, P. A.; Pernod, P.; Preobrazhensky, V.

    2012-03-01

    The possibility of control and tuning of the band structures of phononic crystals offered by the introduction of an active magnetoelastic material and the application of an external magnetic field is studied. Two means to obtain large elastic properties variations in magnetoelastic material are considered: Giant magnetostriction and spin reorientation transition effects. A plane wave expansion method is used to calculate the band structures. The magnetoelastic coupling is taken into account through the consideration of an equivalent piezomagnetic material model with elastic, piezomagnetic, and magnetic permeability tensors varying as a function of the amplitude and orientation of the applied magnetic field. Results of contactless tunability of the absolute bandgap are presented for a two-dimensional phononic crystal constituted of Terfenol-D square rod embedded in an epoxy matrix.

  15. Tunable Micro- and Nanomechanical Resonators

    Science.gov (United States)

    Zhang, Wen-Ming; Hu, Kai-Ming; Peng, Zhi-Ke; Meng, Guang

    2015-01-01

    Advances in micro- and nanofabrication technologies have enabled the development of novel micro- and nanomechanical resonators which have attracted significant attention due to their fascinating physical properties and growing potential applications. In this review, we have presented a brief overview of the resonance behavior and frequency tuning principles by varying either the mass or the stiffness of resonators. The progress in micro- and nanomechanical resonators using the tuning electrode, tuning fork, and suspended channel structures and made of graphene have been reviewed. We have also highlighted some major influencing factors such as large-amplitude effect, surface effect and fluid effect on the performances of resonators. More specifically, we have addressed the effects of axial stress/strain, residual surface stress and adsorption-induced surface stress on the sensing and detection applications and discussed the current challenges. We have significantly focused on the active and passive frequency tuning methods and techniques for micro- and nanomechanical resonator applications. On one hand, we have comprehensively evaluated the advantages and disadvantages of each strategy, including active methods such as electrothermal, electrostatic, piezoelectrical, dielectric, magnetomotive, photothermal, mode-coupling as well as tension-based tuning mechanisms, and passive techniques such as post-fabrication and post-packaging tuning processes. On the other hand, the tuning capability and challenges to integrate reliable and customizable frequency tuning methods have been addressed. We have additionally concluded with a discussion of important future directions for further tunable micro- and nanomechanical resonators. PMID:26501294

  16. Tunable Micro- and Nanomechanical Resonators

    Directory of Open Access Journals (Sweden)

    Wen-Ming Zhang

    2015-10-01

    Full Text Available Advances in micro- and nanofabrication technologies have enabled the development of novel micro- and nanomechanical resonators which have attracted significant attention due to their fascinating physical properties and growing potential applications. In this review, we have presented a brief overview of the resonance behavior and frequency tuning principles by varying either the mass or the stiffness of resonators. The progress in micro- and nanomechanical resonators using the tuning electrode, tuning fork, and suspended channel structures and made of graphene have been reviewed. We have also highlighted some major influencing factors such as large-amplitude effect, surface effect and fluid effect on the performances of resonators. More specifically, we have addressed the effects of axial stress/strain, residual surface stress and adsorption-induced surface stress on the sensing and detection applications and discussed the current challenges. We have significantly focused on the active and passive frequency tuning methods and techniques for micro- and nanomechanical resonator applications. On one hand, we have comprehensively evaluated the advantages and disadvantages of each strategy, including active methods such as electrothermal, electrostatic, piezoelectrical, dielectric, magnetomotive, photothermal, mode-coupling as well as tension-based tuning mechanisms, and passive techniques such as post-fabrication and post-packaging tuning processes. On the other hand, the tuning capability and challenges to integrate reliable and customizable frequency tuning methods have been addressed. We have additionally concluded with a discussion of important future directions for further tunable micro- and nanomechanical resonators.

  17. Optically tunable plasmonic color filters

    Science.gov (United States)

    Liu, Y. J.; Si, G. Y.; Leong, E. S. P.; Wang, B.; Danner, A. J.; Yuan, X. C.; Teng, J. H.

    2012-04-01

    We fabricated sub-wavelength patterned gold plasmonic nanostructures on a quartz substrate through the focused ion beam (FIB) technique. The perforated gold film demonstrated optical transmission peaks in the visible range, which therefore can be used as a plasmonic color filter. Furthermore, by integrating a layer of photoresponsive liquid crystals (LCs) with the gold nanostructure to form a hybrid system, we observed a red-shift of transmission peak wavelength. More importantly, the peak intensity can be further enhanced more than 10% in transmittance due to the refractive index match of the media on both sides of it. By optically pumping the hybrid system using a UV light, nematic-isotropic phase transition of the LCs was achieved, thus changing the effective refractive index experienced by the impinging light. Due to the refractive index change, the transmission peak intensity was modulated accordingly. As a result, an optically tunable plasmonic color filter was achieved. This kind of color filters could be potentially applied to many applications, such as complementary metal-oxide-semiconductor (CMOS) image sensors, liquid crystal display devices, light emitting diodes, etc.

  18. A Tunable Silk Hydrogel Device for Studying Limb Regeneration in Adult Xenopus Laevis.

    Directory of Open Access Journals (Sweden)

    Anne Golding

    Full Text Available In certain amphibian models limb regeneration can be promoted or inhibited by the local wound bed environment. This research introduces a device that can be utilized as an experimental tool to characterize the conditions that promotes limb regeneration in the adult frog (Xenopus laevis model. In particular, this device was designed to manipulate the local wound environment via a hydrogel insert. Initial characterization of the hydrogel insert revealed that this interaction had a significant influence on mechanical forces to the animal, due to the contraction of the hydrogel. The material and mechanical properties of the hydrogel insert were a factor in the device design in relation to the comfort of the animal and the ability to effectively manipulate the amputation site. The tunable features of the hydrogel were important in determining the pro-regenerative effects in limb regeneration, which was measured by cartilage spike formation and quantified by micro-computed tomography. The hydrogel insert was a factor in the observed morphological outcomes following amputation. Future work will focus on characterizing and optimizing the device's observed capability to manipulate biological pathways that are essential for limb regeneration. However, the present work provides a framework for the role of a hydrogel in the device and a path forward for more systematic studies.

  19. Tunable, all-optical quasi-monochromatic Thomson X-ray source

    CERN Document Server

    Khrennikov, K; Buck, A; Xu, J; Heigoldt, M; Veisz, L; Karsch, S

    2014-01-01

    Brilliant X-ray sources are of great interest for many research fields from biology via medicine to material research. The quest for a cost-effective, brilliant source with unprecedented temporal resolution has led to the recent realization of various high-intensity-laser-driven X-ray beam sources. Here we demonstrate the first all-laser-driven, energy-tunable and quasi-monochromatic X-ray source based on Thomson backscattering. This is a decisive step beyond previous results, where the emitted radiation exhibited an uncontrolled broad energy distribution. In the experiment, one part of the laser beam was used to drive a few-fs bunch of quasi-monoenergetic electrons from a Laser-Wakefield Accelerator (LWFA), while the remainder was scattered off the bunch in a near-counter-propagating geometry. When the electron energy was tuned from 10-50 MeV, narrow-bandwidth X-ray spectra peaking at 5-35keV were directly measured, limited in photon energy by the sensitivity curve of our X-ray detector. Due to the ultrashor...

  20. Genetic relationship of organic bases of the quinoline and isoquinoline series from lignite semicoking tars with the initial biological material

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, V.V.; Proskuryakov, V.A.; Podshibyakin, S.I.; Domogatskii, V.V.; Shvykin, A.Y.; Shavyrina, O.A.; Chilachava, K.B. [Leo Tolstoy State Pedagog University, Tula (Russian Federation)

    2002-07-01

    The genetic relationship of quinoline and isoquinoline compounds present in semicoking tars of Kimovsk lignites (near-Moscow fields) with the initial vegetable material is discussed. Transformation pathways of the native compounds in the course of lignite formation are suggested.

  1. The Use of Alternative Raw Material in Production of Pastry Products as a Progressive Direction in Creating the Products of High Biological Value

    Directory of Open Access Journals (Sweden)

    Janа Bachinska

    2017-02-01

    Full Text Available This paper examines the impact of the use of alternative vegetable raw materials in the manufacture of pastry products with high biological value; it presents the results of evaluation of commodity of the developed products and compares them with the main samples presented in Kharkiv trade network. The feasibility of using a mixture of fiber and pumpkin seeds in the technology of pastry production to extend the range of confectionery products of high biological value and products with reduced calories has been proved. Adding the mixture of fiber and pumpkin seeds to biscuits and cakes positively affected the chemical composition of the ready-made product, saturating it with useful and necessary to human body mineral elements, vitamins, dietary fiber.

  2. Materials

    Science.gov (United States)

    Glaessgen, Edward H.; Schoeppner, Gregory A.

    2006-01-01

    NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

  3. Lattice Metamaterials with Mechanically Tunable Poisson's Ratio for Vibration Control

    Science.gov (United States)

    Chen, Yanyu; Li, Tiantian; Scarpa, Fabrizio; Wang, Lifeng

    2017-02-01

    Metamaterials with artificially designed architectures are increasingly considered as new paradigmatic material systems with unusual physical properties. Here, we report a class of architected lattice metamaterials with mechanically tunable negative Poisson's ratios and vibration-mitigation capability. The proposed lattice metamaterials are built by replacing regular straight beams with sinusoidally shaped ones, which are highly stretchable under uniaxial tension. Our experimental and numerical results indicate that the proposed lattices exhibit extreme Poisson's-ratio variations between -0.7 and 0.5 over large tensile deformations up to 50%. This large variation of Poisson's-ratio values is attributed to the deformation pattern switching from bending to stretching within the sinusoidally shaped beams. The interplay between the multiscale (ligament and cell) architecture and wave propagation also enables remarkable broadband vibration-mitigation capability of the lattice metamaterials, which can be dynamically tuned by an external mechanical stimulus. The material design strategy provides insights into the development of classes of architected metamaterials with potential applications including energy absorption, tunable acoustics, vibration control, responsive devices, soft robotics, and stretchable electronics.

  4. Tunable Near-Infrared Luminescence in Tin Halide Perovskite Devices.

    Science.gov (United States)

    Lai, May L; Tay, Timothy Y S; Sadhanala, Aditya; Dutton, Siân E; Li, Guangru; Friend, Richard H; Tan, Zhi-Kuang

    2016-07-21

    Infrared emitters are reasonably rare in solution-processed materials. Recently, research into hybrid organo-lead halide perovskite, originally popular in photovoltaics,1-3 has gained traction in light-emitting diodes (LED) due to their low-cost solution processing and good performance.4-9 The lead-based electroluminescent materials show strong colorful emission in the visible region, but lack emissive variants further in the infrared. The concerns with the toxicity of lead may, additionally, limit their wide-scale applications. Here, we demonstrate tunable near-infrared electroluminescence from a lead-free organo-tin halide perovskite, using an ITO/PEDOT:PSS/CH3NH3Sn(Br1-xIx)3/F8/Ca/Ag device architecture. In our tin iodide (CH3NH3SnI3) LEDs, we achieved a 945 nm near-infrared emission with a radiance of 3.4 W sr(-1) m(-2) and a maximum external quantum efficiency of 0.72%, comparable with earlier lead-based devices. Increasing the bromide content in these tin perovskite devices widens the semiconductor bandgap and leads to shorter wavelength emissions, tunable down to 667 nm. These near-infrared LEDs could find useful applications in a range of optical communication, sensing and medical device applications.

  5. Rigid, non-porous and tunable hybrid p-aminobenzoate/TiO2 materials: Toward a fine structural determination of the immobilized RhCl(Ph3)3 complex

    KAUST Repository

    Espinas, Jeff

    2015-05-01

    By exchange of ligands, Wilkinson complex RhCl(PPh3)3 are immobilized on p-aminobenzoate/TiO2 with different organic loading (6, 11 and 16%). This new hybrid material exhibit a linear correlation between the ligand content of the starting TiO2 and the rhodium loading, showing the accessibility of all surfaces amines fonctions on the non-porous parent materials. 1H, 13C, and 1D, 2D INAQUEDATE refocused and J-resolved 31P solid-state NMR confirm the well-defined structure [(≡TiO)2(n{right tail}2-O2C-C6H4-NH2)RhCl-cis-(PPh3)2]. New immobilized catalysts show interesting activity in cyclohexene hydroformylation.

  6. Determination of clozapine in hair and nail: the role of keratinous biological materials in the identification of a bloated cadaver case.

    Science.gov (United States)

    Chen, Hang; Xiang, Ping; Shen, Min

    2014-02-01

    Keratinous biological materials, such as hair and nails, offer a substantially longer retrospective window of detection compared to other body fluids. Little research on drug analysis in nails is currently being conducted. In this study, the hair and nails from a bloated cadaver was analyzed. The study showed that the forensic toxicology results of keratinous biological materials could provide valuable clues for solving cases. In this study, a method was developed for the extraction and analysis of clozapine from hair and nails. The keratinous bio-samples were washed and then pulverized using a freeze mill. After ultrasonic bath extraction, the supernatants were analyzed by ultra-performance liquid chromatography tandem mass spectrometer (UPLC-MS/MS). The method presented in this study proved to be reliable, specific, selective and sensitive with high precision and accuracy. Clozapine was found in both hair and nails from a long term user's remains, even after serious decomposition. The mean concentration of clozapine in the hair was 322.9 pg/mg and 138.3 pg/mg in the nails. Toxicological results helped police narrow the scope of the investigation and improved the efficiency of the breaking of the case. The findings of the present study demonstrated that the method can be used in forensic investigation. Toxicological results increased the efficiency of cadaver identification and the solving of the case. The study demonstrated that hair and nail analysis could provide vital clues for solving cases and showed the value of keratinous biological materials in the forensics field.

  7. On the Rule of Mixtures for Predicting Stress-Softening and Residual Strain Effects in Biological Tissues and Biocompatible Materials

    Directory of Open Access Journals (Sweden)

    Alex Elías-Zúñiga

    2014-01-01

    Full Text Available In this work, we use the rule of mixtures to develop an equivalent material model in which the total strain energy density is split into the isotropic part related to the matrix component and the anisotropic energy contribution related to the fiber effects. For the isotropic energy part, we select the amended non-Gaussian strain energy density model, while the energy fiber effects are added by considering the equivalent anisotropic volumetric fraction contribution, as well as the isotropized representation form of the eight-chain energy model that accounts for the material anisotropic effects. Furthermore, our proposed material model uses a phenomenological non-monotonous softening function that predicts stress softening effects and has an energy term, derived from the pseudo-elasticity theory, that accounts for residual strain deformations. The model’s theoretical predictions are compared with experimental data collected from human vaginal tissues, mice skin, poly(glycolide-co-caprolactone (PGC25 3-0 and polypropylene suture materials and tracheal and brain human tissues. In all cases examined here, our equivalent material model closely follows stress-softening and residual strain effects exhibited by experimental data.

  8. Preliminary chemical analysis and biological testing of materials from the HRI catalytic two-stage liquefaction (CTSL) process. [Aliphatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Later, D.W.; Wilson, B.W.

    1985-01-01

    Coal-derived materials from experimental runs of Hydrocarbon Research Incorporated's (HRI) catalytic two-stage liquefaction (CTSL) process were chemically characterized and screened for microbial mutagenicity. This process differs from two-stage coal liquefaction processes in that catalyst is used in both stages. Samples from both the first and second stages were class-fractionated by alumina adsorption chromatography. The fractions were analyzed by capillary column gas chromatography; gas chromatography/mass spectrometry; direct probe, low voltage mass spectrometry; and proton nuclear magnetic resonance spectrometry. Mutagenicity assays were performed with the crude and class fractions in Salmonella typhimurium, TA98. Preliminary results of chemical analyses indicate that >80% CTSL materials from both process stages were aliphatic hydrocarbon and polynuclear aromatic hydrocarbon (PAH) compounds. Furthermore, the gross and specific chemical composition of process materials from the first stage were very similar to those of the second stage. In general, the unfractionated materials were only slightly active in the TA98 mutagenicity assay. Like other coal liquefaction materials investigated in this laboratory, the nitrogen-containing polycyclic aromatic compound (N-PAC) class fractions were responsible for the bulk of the mutagenic activity of the crudes. Finally, it was shown that this activity correlated with the presence of amino-PAH. 20 figures, 9 tables.

  9. Gate-Tunable Conducting Oxide Metasurfaces.

    Science.gov (United States)

    Huang, Yao-Wei; Lee, Ho Wai Howard; Sokhoyan, Ruzan; Pala, Ragip A; Thyagarajan, Krishnan; Han, Seunghoon; Tsai, Din Ping; Atwater, Harry A

    2016-09-14

    Metasurfaces composed of planar arrays of subwavelength artificial structures show promise for extraordinary light manipulation. They have yielded novel ultrathin optical components such as flat lenses, wave plates, holographic surfaces, and orbital angular momentum manipulation and detection over a broad range of the electromagnetic spectrum. However, the optical properties of metasurfaces developed to date do not allow for versatile tunability of reflected or transmitted wave amplitude and phase after their fabrication, thus limiting their use in a wide range of applications. Here, we experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in reflectarray geometry. We measure a phase shift of 180° and ∼30% change in the reflectance by applying 2.5 V gate bias. Additionally, we demonstrate modulation at frequencies exceeding 10 MHz and electrical switching of ±1 order diffracted beams by electrical control over subgroups of metasurface elements, a basic requirement for electrically tunable beam-steering phased array metasurfaces. In principle, electrically gated phase and amplitude control allows for electrical addressability of individual metasurface elements and opens the path to applications in ultrathin optical components for imaging and sensing technologies, such as reconfigurable beam steering devices, dynamic holograms, tunable ultrathin lenses, nanoprojectors, and nanoscale spatial light modulators.

  10. Dense Plasma Focus: physics and applications (radiation material science, single-shot disclosure of hidden illegal objects, radiation biology and medicine, etc.)

    Science.gov (United States)

    Gribkov, V. A.; Miklaszewski, R.; Paduch, M.; Zielinska, E.; Chernyshova, M.; Pisarczyk, T.; Pimenov, V. N.; Demina, E. V.; Niemela, J.; Crespo, M.-L.; Cicuttin, A.; Tomaszewski, K.; Sadowski, M. J.; Skladnik-Sadowska, E.; Pytel, K.; Zawadka, A.; Giannini, G.; Longo, F.; Talab, A.; Ul'yanenko, S. E.

    2015-03-01

    The paper presents some outcomes obtained during the year of 2013 of the activity in the frame of the International Atomic Energy Agency Co-ordinated research project "Investigations of Materials under High Repetition and Intense Fusion-Relevant Pulses". The main results are related to the effects created at the interaction of powerful pulses of different types of radiation (soft and hard X-rays, hot plasma and fast ion streams, neutrons, etc. generated in Dense Plasma Focus (DPF) facilities) with various materials including those that are counted as perspective ones for their use in future thermonuclear reactors. Besides we discuss phenomena observed at the irradiation of biological test objects. We examine possible applications of nanosecond powerful pulses of neutrons to the aims of nuclear medicine and for disclosure of hidden illegal objects. Special attention is devoted to discussions of a possibility to create extremely large and enormously diminutive DPF devices and probabilities of their use in energetics, medicine and modern electronics.

  11. Highly tunable elastic dielectric metasurface lenses

    CERN Document Server

    Kamali, Seyedeh Mahsa; Arbabi, Amir; Horie, Yu; Faraon, Andrei

    2016-01-01

    Dielectric metasurfaces are two-dimensional structures composed of nano-scatterers that manipulate phase and polarization of optical waves with subwavelength spatial resolution, enabling ultra-thin components for free-space optics. While high performance devices with various functionalities, including some that are difficult to achieve using conventional optical setups have been shown, most demonstrated components have a fixed functionality. Here we demonstrate highly tunable metasurface devices based on subwavelength thick silicon nano-posts encapsulated in a thin transparent elastic polymer. As proof of concept, we demonstrate a metasurface microlens operating at 915 nm, with focal distance tuning from 600 $\\mu$m to 1400 $\\mu$m through radial strain, while maintaining a diffraction limited focus and a focusing efficiency above 50$\\%$. The demonstrated tunable metasurface concept is highly versatile for developing ultra-slim, multi-functional and tunable optical devices with widespread applications ranging f...

  12. Tunable random lasing behavior in plasmonic nanostructures

    Science.gov (United States)

    Yadav, Ashish; Zhong, Liubiao; Sun, Jun; Jiang, Lin; Cheng, Gary J.; Chi, Lifeng

    2017-01-01

    Random lasing is desired in plasmonics nanostructures through surface plasmon amplification. In this study, tunable random lasing behavior was observed in dye molecules attached with Au nanorods (NRs), Au nanoparticles (NPs) and Au@Ag nanorods (NRs) respectively. Our experimental investigations showed that all nanostructures i.e., Au@AgNRs, AuNRs & AuNPs have intensive tunable spectral effects. The random lasing has been observed at excitation wavelength 532 nm and varying pump powers. The best random lasing properties were noticed in Au@AgNRs structure, which exhibits broad absorption spectrum, sufficiently overlapping with that of dye Rhodamine B (RhB). Au@AgNRs significantly enhance the tunable spectral behavior through localized electromagnetic field and scattering. The random lasing in Au@AgNRs provides an efficient coherent feedback for random lasers.

  13. Gate-tunable conducting oxide metasurfaces

    CERN Document Server

    Huang, Yao-Wei; Sokhoyan, Ruzan; Pala, Ragip; Thyagarajan, Krishnan; Han, Seunghoon; Tsai, Din Ping; Atwater, Harry A

    2015-01-01

    Metasurfaces composed of planar arrays of sub-wavelength artificial structures show promise for extraordinary light manipulation; they have yielded novel ultrathin optical components such as flat lenses, wave plates, holographic surfaces and orbital angular momentum manipulation and detection over a broad range of electromagnetic spectrum. However the optical properties of metasurfaces developed to date do not allow for versatile tunability of reflected or transmitted wave amplitude and phase after fabrication, thus limiting their use in a wide range of applications. Here, we experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in a reflectarray geometry. We measure a phase shift of {\\pi} and ~ 30% change in the reflectanc...

  14. Rational design of functional and tunable oscillating enzymatic networks

    Science.gov (United States)

    Semenov, Sergey N.; Wong, Albert S. Y.; van der Made, R. Martijn; Postma, Sjoerd G. J.; Groen, Joost; van Roekel, Hendrik W. H.; de Greef, Tom F. A.; Huck, Wilhelm T. S.

    2015-02-01

    Life is sustained by complex systems operating far from equilibrium and consisting of a multitude of enzymatic reaction networks. The operating principles of biology's regulatory networks are known, but the in vitro assembly of out-of-equilibrium enzymatic reaction networks has proved challenging, limiting the development of synthetic systems showing autonomous behaviour. Here, we present a strategy for the rational design of programmable functional reaction networks that exhibit dynamic behaviour. We demonstrate that a network built around autoactivation and delayed negative feedback of the enzyme trypsin is capable of producing sustained oscillating concentrations of active trypsin for over 65 h. Other functions, such as amplification, analog-to-digital conversion and periodic control over equilibrium systems, are obtained by linking multiple network modules in microfluidic flow reactors. The methodology developed here provides a general framework to construct dissipative, tunable and robust (bio)chemical reaction networks.

  15. Circadian-effect engineering of solid-state lighting spectra for beneficial and tunable lighting.

    Science.gov (United States)

    Dai, Qi; Shan, Qifeng; Lam, Hien; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-09-05

    Optimization of solid-state lighting spectra is performed to achieve beneficial and tunable circadian effects. First, the minimum spectral circadian action factor (CAF) of 2700 K white light-emitting diodes (LEDs) is studied for applications where biologically active illumination is undesirable. It is found that white-LEDs based on (i) RGB chips, (ii) blue & red chips plus green phosphor, and (iii) blue chip plus green & red phosphors are the corresponding minimum-CAF solutions at color-rendering index (CRI) requirements of 80, 90, and 95, respectively. Second, maximum CAF tunability of LED clusters is studied for dynamic daylighting applications. A dichromatic phosphor-converted blue-centered LED, a dichromatic phosphor-converted green-centered LED, and a monochromatic red LED are grouped to obtain white spectra between 2700 K and 6500 K. A maximum CAF tunability of 3.25 times is achieved with CRI above 90 and luminous efficacy of radiation of 313 - 373 lm/W. We show that our approaches have advantages over previously reported solutions on system simplicity, minimum achievable CAF value, CAF tunability range, and light source efficacy.

  16. Polyacrylate membranes for tunable liquid-filled microlenses

    Science.gov (United States)

    Zhang, Wei; Zappe, Hans; Seifert, Andreas

    2013-04-01

    We present the use of polyacrylate membranes for the fabrication of pneumatically actuated variable lenses. Whereas the most commonly used membrane material for tunable liquid-filled lenses is polydimethylsiloxane (PDMS), polyacrylate membranes have the advantages of high resistance to swelling in silicone oil and enhanced compatibility with a wide range of aqueous optical liquids. These features are quantitatively demonstrated by comparing the material properties and performance of PDMS and polyacrylate membrane lenses. The optical transparency of polyacrylate is more than 92%. The surface roughness is below 3.3 nm rms, and reversible elastic deformation could be demonstrated. Optical measurements show that the cutoff frequency of the modulation transfer function of polyacrylate lenses with different liquid fillings, using a reference contrast of 0.2, is more than 1.5 times larger than that of the same system assembled with PDMS membranes filled with water.

  17. Tunable Optofluidic Third Order DFB Dye Laser

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Kristensen, Anders

    2007-01-01

    We present a low-threshold polymer-based nanofluidic dye laser. By employing a third order DFB laser resonator, we demonstrate a threshold fluence of ~7 muJ/mm2 and a tunability of 45 nm using a single laser dye......We present a low-threshold polymer-based nanofluidic dye laser. By employing a third order DFB laser resonator, we demonstrate a threshold fluence of ~7 muJ/mm2 and a tunability of 45 nm using a single laser dye...

  18. Tunable high-gradient permanent magnet quadrupoles

    CERN Document Server

    Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

    2014-01-01

    A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

  19. Generation and excitation of different orbital angular momentum states in a tunable microstructure optical fiber.

    Science.gov (United States)

    Huang, Wei; Liu, Yan-ge; Wang, Zhi; Zhang, Wanchen; Luo, Mingming; Liu, Xiaoqi; Guo, Junqi; Liu, Bo; Lin, Lie

    2015-12-28

    A tunable microstructure optical fiber for different orbital angular momentum states generation is proposed and investigated by simulation. The microstructure optical fiber is composed of a high refractive index ring and a hollow core surrounded by four small air holes. The background material of the microstructure fiber is pure silica. The hollow core and the surrounded four small air holes are infiltrated by optical functional material whose refractive index can be modulated via physical parameters, leading to the conversion between circular polarized fundamental mode and different orbital angular momentum states at tunable operating wavelengths. A theoretical model is established and the coupling mechanism is systematically analyzed and investigated based on coupled mode theory. The fiber length can be designed specifically to reach the maximum coupling efficiency for every OAM mode respectively, and can also be fixed at a certain value for several OAM modes generation under tunable refractive index conditions. The proposed fiber coupler is flexible and compact, making it a good candidate for tunable OAM generation and sensing systems.

  20. Biology Notes.

    Science.gov (United States)

    School Science Review, 1981

    1981-01-01

    Outlines a variety of laboratory procedures, techniques, and materials including construction of a survey frame for field biology, a simple tidal system, isolation and applications of plant protoplasts, tropisms, teaching lung structure, and a key to statistical methods for biologists. (DS)

  1. Marine Biology

    Science.gov (United States)

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  2. Biology Notes.

    Science.gov (United States)

    School Science Review, 1984

    1984-01-01

    Presents information on the teaching of nutrition (including new information relating to many current O-level syllabi) and part 16 of a reading list for A- and S-level biology. Also includes a note on using earthworms as a source of material for teaching meiosis. (JN)

  3. Nanoporous carbon tunable resistor/transistor and methods of production thereof

    Science.gov (United States)

    Biener, Juergen; Baumann, Theodore F; Dasgupta, Subho; Hahn, Horst

    2014-04-22

    In one embodiment, a tunable resistor/transistor includes a porous material that is electrically coupled between a source electrode and a drain electrode, wherein the porous material acts as an active channel, an electrolyte solution saturating the active channel, the electrolyte solution being adapted for altering an electrical resistance of the active channel based on an applied electrochemical potential, wherein the active channel comprises nanoporous carbon arranged in a three-dimensional structure. In another embodiment, a method for forming the tunable resistor/transistor includes forming a source electrode, forming a drain electrode, and forming a monolithic nanoporous carbon material that acts as an active channel and selectively couples the source electrode to the drain electrode electrically. In any embodiment, the electrolyte solution saturating the nanoporous carbon active channel is adapted for altering an electrical resistance of the nanoporous carbon active channel based on an applied electrochemical potential.

  4. Tunable nanostructured composite with built-in metallic wire-grid electrode

    Energy Technology Data Exchange (ETDEWEB)

    Micheli, Davide, E-mail: davide.micheli@uniroma1.it; Pastore, Roberto; Marchetti, Mario [Department of Astronautics, Electrical and Energy Engineering, University of Rome Sapienza Via Eudossiana, 18, 00184 – Rome (Italy); Gradoni, Gabriele [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Paint Branch Drive, MD-20740 (United States)

    2013-11-15

    In this paper, the authors report an experimental demonstration of microwave reflection tuning in carbon nanostructure-based composites by means of an external voltage supplied to the material. DC bias voltages are imparted through a metal wire-grid. The magnitude of the reflection coefficient is measured upon oblique plane-wave incidence. Increasing the bias from 13 to 700 V results in a lowering of ∼20 dB, and a “blueshift” of ∼600 MHz of the material absorption resonance. Observed phenomena are ascribed to a change of the dielectric response of the carbon material. Inherently, the physical role of tunneling between nanofillers (carbon nanotubes) is discussed. Achievements aim at the realization of a tunable absorber. There are similar studies in literature that focus on tunable metamaterials operating at either optical or THz wavelengths.

  5. Tunable nanostructured composite with built-in metallic wire-grid electrode

    Directory of Open Access Journals (Sweden)

    Davide Micheli

    2013-11-01

    Full Text Available In this paper, the authors report an experimental demonstration of microwave reflection tuning in carbon nanostructure-based composites by means of an external voltage supplied to the material. DC bias voltages are imparted through a metal wire-grid. The magnitude of the reflection coefficient is measured upon oblique plane-wave incidence. Increasing the bias from 13 to 700 V results in a lowering of ∼20 dB, and a “blueshift” of ∼600 MHz of the material absorption resonance. Observed phenomena are ascribed to a change of the dielectric response of the carbon material. Inherently, the physical role of tunneling between nanofillers (carbon nanotubes is discussed. Achievements aim at the realization of a tunable absorber. There are similar studies in literature that focus on tunable metamaterials operating at either optical or THz wavelengths.

  6. Bandgap tunability at single-layer molybdenum disulphide grain boundaries

    KAUST Repository

    Huang, Yu Li

    2015-02-17

    Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85±0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

  7. Widely tunable infrared semiconductor Mie resonators (Conference Presentation)

    Science.gov (United States)

    Lewi, Tomer; Iyer, Prasad P.; Butakov, Nikita A.; Mikhailovsky, Alexander A.; Schuller, Jon A.

    2016-09-01

    Optical antenna metasurfaces have attracted substantial attention in recent years, as they may enable new classes of planar optical elements. However, actively tuning nanoantenna resonances, whether dielectric or plasmonic, remains an unresolved challenge. In this work, we investigate tuning mid-infrared (MIR) Mie resonances in semiconductor subwavelength particles by directly modulating the permittivity with free charge carriers. Using femtosecond laser ablation, we fabricate spherical silicon and germanium particles of varying sizes and doping concentrations. Single-particle infrared spectra reveal electric and magnetic dipole, quadrupole, and hexapole resonances. We first demonstrate size-dependent Si and Ge Mie resonances spanning the entire mid-infrared (2-16 μm) spectral range. We subsequently show doping-dependent resonance frequency shifts that follow simple Drude models. Taking advantage of the large doping dependence of Si and Ge MIR permittivities, we demonstrate a huge tunability of Mie resonance wavelengths (up to 9 μm) over a broad 2-16 μm MIR range. This tuning range corresponds to changes of permittivity as large as 30 within a single material system, culminating in the emergence of plasmonic modes at high carrier densities and long wavelengths. We also demonstrate dynamic tuning of intrinsic semiconductor antennas using thermo-optic effects. These findings demonstrate the potential for actively tuning infrared Mie resonances, thus providing an excellent platform for tunable metamaterials.

  8. Experimental study on the adhesion, migration and three-dimensional growth of Schwann cells on absorbable biological materials

    Institute of Scientific and Technical Information of China (English)

    王光林; 林卫; 杨志明; 裴福兴; 刘雷

    2003-01-01

    Objective: To study the adhesion, migration and three-dimentional growth of Schwann cells on PLA (polylactic acid) nonspinning fibre cloth and polyglycolic/polylactic acid (PLGA) fibres.Methods: Schwann cells/ECM gel solution and PLA nonspinning fibre cloth and PLGA fibres pretreated by collagen, polylysine and ECM were co-cultured. Then the migration and three-dimensional growth of Schwann cells on the fibres were observed under phase contrast microscope and laser scanning confocal microscope.Conclusions: ECM gel can facilitate the adhesion, growth and migration of Schwann cells on the seteroframe. It is a good integrating material for tissue engineering bioartificial nerve.

  9. An Investigation into the Effects of Interface Stress and Interfacial Arrangement on Temperature Dependent Thermal Properties of a Biological and a Biomimetic Material

    Energy Technology Data Exchange (ETDEWEB)

    Tomar, Vikas

    2015-01-13

    A significant effort in the biomimetic materials research is on developing materials that can mimic and function in the same way as biological tissues, on bio-inspired electronic circuits, on bio-inspired flight structures, on bio-mimetic materials processing, and on structural biomimetic materials, etc. Most structural biological and biomimetic material properties are affected by two primary factors: (1) interfacial interactions between an organic and an inorganic phase usually in the form of interactions between an inorganic mineral phase and organic protein network; and (2) structural arrangement of the constituents. Examples are exoskeleton structures such as spicule, nacre, and crustacean exoskeletons. A significant effort is being directed towards making synthetic biomimetic materials based on a manipulation of the above two primary factors. The proposed research is based on a hypothesis that in synthetic materials with biomimetic morphology thermal conductivity, k, (how fast heat is carried away) and thermal diffusivity, D, (how fast a material’s temperature rises: proportional to the ratio of k and heat capacity) can be engineered to be either significantly low or significantly high based on a combination of chosen interface orientation and interfacial arrangement in comparison to conventional material microstructures with the same phases and phase volume fractions. METHOD DEVELOPMENT 1. We have established a combined Raman spectroscopy and nanomechanical loading based experimental framework to perform environment (liquid vs. air vs. vacuum) dependent and temperature dependent (~1000 degree-C) in-situ thermal diffusivity measurements in biomaterials at nanoscale to micron scale along with the corresponding analytical theoretic calculations. (Zhang and Tomar, 2013) 2. We have also established a new classical molecular simulation based framework to measure thermal diffusivity in biomolecular interfaces. We are writing a publication currently (Qu and Tomar

  10. Automated annotation of chemical names in the literature with tunable accuracy

    Directory of Open Access Journals (Sweden)

    Zhang Jun D

    2011-11-01

    corpus and it is possible that the algorithm can be applied to papers from chemical physics, material, polymer and environmental science, as well as patents, biological assay descriptions and other textual data.

  11. Tunable Sparse Network Coding for Multicast Networks

    DEFF Research Database (Denmark)

    Feizi, Soheil; Roetter, Daniel Enrique Lucani; Sørensen, Chres Wiant;

    2014-01-01

    This paper shows the potential and key enabling mechanisms for tunable sparse network coding, a scheme in which the density of network coded packets varies during a transmission session. At the beginning of a transmission session, sparsely coded packets are transmitted, which benefits decoding co...

  12. Three-dimensional broadband tunable terahertz metamaterials

    DEFF Research Database (Denmark)

    Fan, Kebin; Strikwerda, Andrew; Zhang, Xin;

    2013-01-01

    We present optically tunable magnetic three-dimensional (3D) metamaterials at terahertz (THz) frequencies which exhibit a tuning range of ~30% of the resonance frequency. This is accomplished by fabricating 3D array structures consisting of double-split-ring resonators (DSRRs) on silicon on sapph...

  13. Tunable metamaterial dual-band terahertz absorber

    Science.gov (United States)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  14. Compact microstrip bandpass filter with tunable notch

    DEFF Research Database (Denmark)

    Christensen, Silas; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    Two different designs combining a bandpass and a notch filter are developed to operate in the receiving band from 350–470 MHz. The bandpass filter is designed from a simple structure, by use of only four short circuited stubs and a half wavelength transmission line connecting the stubs. The tunable...

  15. Examination of Bone Marrow Mesenchymal Stem Cells Seeded onto Poly(3-hydroxybutyrate-co-3-hydroxybutyrate Biological Materials for Myocardial Patch

    Directory of Open Access Journals (Sweden)

    Junsheng Mu

    2014-03-01

    Full Text Available The implantation of the Bone Marrow Mesenchymal Stem Cells (BMSCs into the heart has been reported to be effective for the treatment of myocardial infarction; however, the methods most suitable for supporting stem cell growth in a myocardial patch, still remain unknown. We used a new polymer material composed of poly(3-hydroxybutyrate-co-3-hydroxybutyrate [P(3HB-co-3HB] co-cultured with BMSCs to create a myocardial patch. The BMSCs were obtained from healthy male BSL-C57 mice. The cells were treated with 5-azacytidine to investigate their differentiation into cardiomyocytes. The cells were seeded for 24 hours onto the P(3HB-co-3HB biological material films (n=8. Cell-biomaterial constructs were fixed and analyzed using different methods. BMSCs were CD34-, CD45-, CD90+ (low and CD73+. The cells were stained with anti-cardiac troponin T (cTnT and anti-connexin 43 (CX43 antibodies after 5-azacytidine treatment. Scanning electron microscopy revealed that the morphology of the BMSC was normal and that cell numbers were more abundant on the P(3HB-co-3HB material surfaces. The growth curve of the BMSCs on the biomaterial patches showed the P(3HB-co-3HB material enhanced good stem cell growth. Owing to its excellent biocompatibility and biodegradability properties, in particular its porosity, the P(3HB-co-3HB is hailed as an optimal material to support myocardial cell growth and to create a myocardial patch in patients with myocardial infarction.

  16. Tunable High Brightness Semiconductor Sources

    Science.gov (United States)

    2015-05-01

    along with calculated diffraction pattern, rep- resenting faithful reproduction material composition and layer thickness. Inset is as example surface...Chen, and J. Tian, “Nonlinear optical properties of graphene-based materials,” Chin. Sci. Bull ., vol. 57, pp. 2971–2982, 2012. [67] X. Zhang, Z. Liu...211909, 2011. [77] B. C. A. Das and A. K. Sood, “Raman spectroscopy of graphene on different substrates and influence of defects,” Bull . Mater. Sci, vol

  17. FOB-SH: Fragment orbital-based surface hopping for charge carrier transport in organic and biological molecules and materials

    Science.gov (United States)

    Spencer, J.; Gajdos, F.; Blumberger, J.

    2016-08-01

    We introduce a fragment orbital-based fewest switches surface hopping method, FOB-SH, designed to efficiently simulate charge carrier transport in strongly fluctuating condensed phase systems such as organic semiconductors and biomolecules. The charge carrier wavefunction is expanded and the electronic Hamiltonian constructed in a set of singly occupied molecular orbitals of the molecular sites that mediate the charge transfer. Diagonal elements of the electronic Hamiltonian (site energies) are obtained from a force field, whereas the off-diagonal or electronic coupling matrix elements are obtained using our recently developed analytic overlap method. We derive a general expression for the exact forces on the adiabatic ground and excited electronic state surfaces from the nuclear gradients of the charge localized electronic states. Applications to electron hole transfer in a model ethylene dimer and through a chain of ten model ethylenes validate our implementation and demonstrate its computational efficiency. On the larger system, we calculate the qualitative behaviour of charge mobility with change in temperature T for different regimes of the intermolecular electronic coupling. For small couplings, FOB-SH predicts a crossover from a thermally activated regime at low temperatures to a band-like transport regime at higher temperatures. For higher electronic couplings, the thermally activated regime disappears and the mobility decreases according to a power law. This is interpreted by a gradual loss in probability for resonance between the sites as the temperature increases. The polaron hopping model solved for the same system gives a qualitatively different result and underestimates the mobility decay at higher temperatures. Taken together, the FOB-SH methodology introduced here shows promise for a realistic investigation of charge carrier transport in complex organic, aqueous, and biological systems.

  18. Photo-crosslinked poly(epsilon-caprolactone fumarate) networks for guided peripheral nerve regeneration: material properties and preliminary biological evaluations.

    Science.gov (United States)

    Wang, Shanfeng; Yaszemski, Michael J; Knight, Andrew M; Gruetzmacher, James A; Windebank, Anthony J; Lu, Lichun

    2009-06-01

    In an effort to achieve suitable biomaterials for peripheral nerve regeneration, we present a material design strategy of combining a crystallite-based physical network and a crosslink-based chemical network. Biodegradable polymer disks and conduits have been fabricated by photo-crosslinking three poly(epsilon-caprolactone fumarate)s (PCLF530, PCLF1250, and PCLF2000), which were synthesized from the precursor poly(epsilon-caprolactone) (PCL) diols with nominal molecular weights of 530, 1250, and 2000 g mol(-1), respectively. Thermal properties such as glass transition temperature (T(g)), melting temperature (T(m)), and crystallinity of photo-crosslinked PCLFs were examined and correlated with their rheological and mechanical properties. Furthermore, in vitro degradation of uncrosslinked and crosslinked PCLFs in PBS crosslinked PCLFs in 1 N NaOH aqueous solution at 37 degrees C was studied. In vitro cytocompatibility, attachment, and proliferation of Schwann cell precursor line SPL201 cells on three PCLF networks were investigated. Crosslinked PCLF2000 with the highest crystallinity and mechanical properties was found to best support cell attachment and proliferation. Using a new photo-crosslinking method, single-lumen crosslinked PCLF nerve conduits without defects were fabricated in a glass mold. Crosslinked PCLF2000 nerve conduits were selected for evaluation in a 1cm gap rat sciatic nerve model. Histological evaluation demonstrated that the material was biocompatible with sufficient strength to hold sutures in place after 6 and 17 weeks of implantation. Nerve cable with myelinated axons was found in the crosslinked PCLF2000 nerve conduit.

  19. Comparison of biological H2S removal characteristics between a composite packing material with and without functional microorganisms

    Science.gov (United States)

    Zhu, Rencheng; Li, Shunyi; Bao, Xiaofeng; Dumont, Éric

    2017-01-01

    The performances of two identical biofilters, filled with a new composite packing material (named CM-5) embedded with functional microorganisms or sterilized CM-5 without microorganisms, were investigated for H2S treatment. Running parameters in terms of microbial counts, pressure drops, and inlet and outlet H2S concentrations were measured. The results show that the microbial count of the CM-5 was approximately ×105 CFU/g before being filled into the biofilter, while that of the sterilized CM-5 was negligible. The functional microorganisms embedded in CM-5 adapted to the environment containing H2S quickly. In most cases, pressure drops of the CM-5 biofilter were slightly higher than those of the sterilized CM-5 biofilter when the gas flow rate was 0.6–2.5 m3/h. The maximum elimination capacity (EC) of the CM-5 biofilter in treating H2S could reach up to 65 g/(m3·h) when the loading rate (LR) was approximately 80 g/(m3·h). If the LR was much higher, the measured EC showed a slight downward trend. The experimental ECs of biofilters were fitted by two typical dynamic models: the Michaelis-Menten model and the Haldane model. Compared with the Michaelis-Menten model, the Haldane model fit the experimental ECs better for the two biofilters because of the presence of the substrate inhibition behaviour. PMID:28198800

  20. Comparison of biological H2S removal characteristics between a composite packing material with and without functional microorganisms

    Science.gov (United States)

    Zhu, Rencheng; Li, Shunyi; Bao, Xiaofeng; Dumont, Éric

    2017-02-01

    The performances of two identical biofilters, filled with a new composite packing material (named CM-5) embedded with functional microorganisms or sterilized CM-5 without microorganisms, were investigated for H2S treatment. Running parameters in terms of microbial counts, pressure drops, and inlet and outlet H2S concentrations were measured. The results show that the microbial count of the CM-5 was approximately ×105 CFU/g before being filled into the biofilter, while that of the sterilized CM-5 was negligible. The functional microorganisms embedded in CM-5 adapted to the environment containing H2S quickly. In most cases, pressure drops of the CM-5 biofilter were slightly higher than those of the sterilized CM-5 biofilter when the gas flow rate was 0.6–2.5 m3/h. The maximum elimination capacity (EC) of the CM-5 biofilter in treating H2S could reach up to 65 g/(m3·h) when the loading rate (LR) was approximately 80 g/(m3·h). If the LR was much higher, the measured EC showed a slight downward trend. The experimental ECs of biofilters were fitted by two typical dynamic models: the Michaelis-Menten model and the Haldane model. Compared with the Michaelis-Menten model, the Haldane model fit the experimental ECs better for the two biofilters because of the presence of the substrate inhibition behaviour.

  1. Biological potential of extraterrestrial materials. 2. Microbial and plant responses to nutrients in the Murchison carbonaceous meteorite

    Science.gov (United States)

    Mautner, M. N.; Conner, A. J.; Killham, K.; Deamer, D. W.

    1997-01-01

    Meteoritic materials are investigated as potential early planetary nutrients. Aqueous extracts of the Murchison C2 carbonaceous meteorite are utilized as a sole carbon source by microorganisms, as demonstrated by the genetically modified Pseudomonas fluorescence equipped with the lux gene. Nutrient effects are observed also with the soil microorganisms Nocardia asteroides and Arthrobacter pascens that reach populations up to 5 x 10(7) CFU/ml in meteorite extracts, similar to populations in terrestrial soil extracts. Plant tissue cultures of Asparagus officinalis and Solanum tuberosum (potato) exhibit enhanced pigmentation and some enhanced growth when meteorite extracts are added to partial nutrient media, but inhibited growth when added to full nutrient solution. The meteorite extracts lead to large increases in S, Ca, Mg, and Fe plant tissue contents as shown by X-ray fluorescence, while P, K, and Cl contents show mixed effects. In both microbiological and plant tissue experiments, the nutrient and inhibitory effects appear to be best balanced for growth at about 1:20 (extracted solid : H2O) ratios. The results suggest that solutions in cavities in meteorites can provide efficient concentrated biogenic and early nutrient environments, including high phosphate levels, which may be the limiting nutrient. The results also suggest that carbonaceous asteroid resources can sustain soil microbial activity and provide essential macronutrients for future space-based ecosystems.

  2. Preface - From molecules to molecular materials, biological molecular systems and nanostructures: A collection of contributions presented at the XIIIth International Conference on Molecular Spectroscopy

    Science.gov (United States)

    Ratajczak, Henryk; Drozd, Marek; Fausto, Rui

    2016-12-01

    This volume contains a series of selected contributions presented at the XIIIth International Conference on Molecular Spectroscopy (ICMS): "From Molecules to Molecular Materials, Biological Molecular Systems and Nanostructures" held in Wrocław, Poland, 9-12 September 2015, under the auspices of the Mayor of Wrocław and the European Academy of Sciences, Arts and Humanities. Wrocław was chosen not accidentally as venue for the conference. With more than a thousand years of history, Wrocław is the location of one of the oldest universities in Central Europe. Being a place where education and science play major roles in the daily life of its inhabitants, Wrocław is also a privileged center for spectroscopy in Poland.

  3. The on-line detection of biological particle emissions from selected agricultural materials using the WIBS-4 (Waveband Integrated Bioaerosol Sensor) technique

    Science.gov (United States)

    O'Connor, David J.; Healy, David A.; Sodeau, John R.

    2013-12-01

    Agricultural activities have, for some time, been linked to adverse health effects such as Farmers' lung, hypersensitivity pneumonitis, aspergillosis and chronic obstructive pulmonary disease (COPD) This connection is known to be, at least in part, due to the numerous microbiological organisms that live and grow on materials found in occupational settings such as barns, animal shelters, stables and composting sites. Traditional techniques for determining biological release of fungal spores and bacteria require intensive, experienced human resources and considerable time to determine ambient concentrations. However more recently the fluorescence and light scattering signals obtained from primary biological aerosol particles (PBAP) have been utilised for their near real-time counting and characterisation abilities. In the current study, data collected for the bioaerosol types released from hay and silage were counted and identified using a combination of the WIBS-4 bioaerosol sensor approach and impaction/optical microscopy. Particle emissions were characterised according to particle numbers, their size distributions, particle asymmetry values and fluorescence characteristics. The variables obtained were shown to provide potential “fingerprint” signatures for PBAP emissions emanating from two important compost components, namely, silage and hay. Comparisons between the data acquired by the WIBS-4 bioaerosol sensor, optical microscopy findings and also previous literature suggest that the likely identification of Aspergillus/Penicillium type spores and bacterial species released from hay and silage was achieved on a relatively rapid time-scale.

  4. Development and application of photosensitive device systems to studies of biological and organic materials. Progress report, January 1, 1993--December 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, S.M.; Reynolds, G.T.

    1993-09-14

    This progress report summarizes results, as of August, 1993, for DOE grant DE-FG-02-76ER60522 during the fiscal period 1/1/93 to 12/31/93, which is the first year of a 3-year grant cycle. The overall goals of the grant are to develop advanced x-ray detector technologies, especially as applicable for biological and materials research at the national laboratories, and to train graduate and post-doctoral students on the use of these technologies via the performance of original biological and materials research. As summarized below, there has been good progress toward achieving the research goals of the original 3-year proposal; in consequence, the research plan and the total budget for the rest of 1993 and beyond is still well described by the original proposal. Accomplishments since the last progress report include: (A) A 1k x 1k fiber optically coupled CCD detector was assembled, tested at CHESS and is slated for extended user trials this Fall. A 2k x 2k CCD detector is being assembled for permanent installation at CHESS. (B) X-ray detector phosphors, calibration techniques, and system software have been developed. (C) The design of a Pixel Array Detector, a collaborative project with the Advanced Photon Source, has been initiated. (D) The properties of biomembrane lipids under extremes of pressure have been investigated. High pressure instrumentation and techniques have been developed. (E) The physics of mesophase formation in biomembrane lipid, surfactant, and polymeric systems have been studied. This includes study of the interaction of membrane proteins with elastically strained lipid bilayers. (G) Work has been initiated on the use of thermal diffuse scatter from proteins as a probe of protein dynamics. (H) Studies on luminescent phenomena have been reported. Since the last progress report (dated 15 May 1992), this work has resulted in 10 published papers, 7 abstracts, 1 Ph.D. thesis and 1 technical report.

  5. Stiffness control of magnetorheological gels for adaptive tunable vibration absorber

    Science.gov (United States)

    Kim, Hyun Kee; Kim, Hye Shin; Kim, Young-Keun

    2017-01-01

    In this study, a stiffness feedback control system for magnetorheological (MR) gel—a smart material of variable stiffness—is proposed, toward the design of a tunable vibration absorber that can adaptively tune to a time varying disturbance in real time. A PID controller was designed to track the required stiffness of the MR gel by controlling the magnitude of the target external magnetic field pervading the MR gel. This paper proposes a novel magnetic field generator that could produce a variable magnetic field with low energy consumption. The performance of the MR gel stiffness control was validated through experiments that showed the MR gel absorber system could be automatically tuned from 56 Hz to 67 Hz under a field of 100 mT to minimize the vibration of the primary system.

  6. Geometry and design of origami bellows with tunable response

    Science.gov (United States)

    Reid, Austin; Lechenault, Frederic; Rica, Sergio; Adda-Bedia, Mokhtar

    2017-01-01

    Origami folded cylinders (origami bellows) have found increasingly sophisticated applications in space flight and medicine. In spite of this interest, a general understanding of the mechanics of an origami folded cylinder has been elusive. With a newly developed set of geometrical tools, we have found an analytic solution for all possible cylindrical rigid-face states of both Miura-ori and triangular tessellations. Although an idealized bellows in both of these families may have two allowed rigid-face configurations over a well-defined region, the corresponding physical device, limited by nonzero material thickness and forced to balance hinge and plate-bending energy, often cannot stably maintain a stowed configuration. We have identified the parameters that control this emergent bistability, and we have demonstrated the ability to design and fabricate bellows with tunable deployability.

  7. Electrically tunable topological superconductivity and Majorana fermions in two dimensions

    Science.gov (United States)

    Wang, Jing

    2016-12-01

    The external controllability of topological superconductors and Majorana fermions would be important both for fundamental and practical interests. Here we predict the electric-field control of Majorana fermions in two-dimensional topological superconductors utilizing a topological insulator thin-film proximity coupled to a conventional s -wave superconductor. With ferromagnetic ordering, the tunable structure inversion asymmetry by vertical electric field could induce topological quantum phase transition and realize a chiral topological superconductor state. A zero-energy Majorana bound state appears at the boundary of an applied electric-field spot, which can be observed by scanning tunneling microscopy. Furthermore, the structure inversion asymmetry could also enlarge the helical topological superconductor state in the phase diagram, making the realization of such an exotic state more feasible. The electrical control of topological phases could further apply to van der Waals materials such as two-dimensional transition-metal dichalcogenides.

  8. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    Science.gov (United States)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  9. Tunable multiband ferroelectric devices for reconfigurable RF-frontends

    CERN Document Server

    Zheng, Yuliang

    2013-01-01

    Reconfigurable RF-frontends aim to cope with the continuous pursuit of wider frequency coverage, higher efficiency, further compactness and lower cost of ownership. They are expected to lay the foundations of future software defined or cognitive radios. As a potential enabling technology for the frontends, the tunable ferroelectric devices have shown not only enhanced performance but also new functionalities. This book explores the recent developments in the field. It provides a cross-sectional perspective on the interdisciplinary research. With attention to the devices based on ceramic thick-films and crystal thin-films, the book reviews the adapted technologies of material synthesis, film deposition and multilayer circuitry. Next, it highlights the original classes of thin-film ferroelectric devices, including stratified metal-insulator-metal varactors with suppression of acoustic resonance and programmable bi-stable high frequency capacitors. At the end the book analyzes how the frontends can be reformed b...

  10. Biological preconcentrator

    Science.gov (United States)

    Manginell, Ronald P.; Bunker, Bruce C.; Huber, Dale L.

    2008-09-09

    A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

  11. Admissible loads in wastewater treatment, using a recycled support materials in a biological aerated filter; Cargas admisibles en depuracion de aguas residuales, usando material reciclado como soporte de un filtro sumergido

    Energy Technology Data Exchange (ETDEWEB)

    Osorio Robles, F. [E.T.S.I. de Caminos Canales y Puertos de Granada (Spain)

    2000-07-01

    This study places in the context of the research into Biological Aerated Filters that the Environmental Technology and Environmental Microbiology Research Group (University of Granada, Spain) has been developing for several years. We have achieved a high level of optimization of the system, using a recycled ceramic-based materials as biofilm support. It enables to give some design parameters, which will make possible the practical application in the future. In this article the relations among volumetric and hydraulic loads applied and effluent concentrations and elimination rates in relation to several pollutants are presented. The oxygen supplied has been accurately controlled, and the relation among the consumption value and the loads applied and the system efficiency obtained is presented. The tests were performed at a pilot plant with full scale height. The influent used was the primary effluent of a conventional treatment plant and the operational flow was counter-current flow. (Author) 11 refs.

  12. Cis-Antisense Transcription Gives Rise to Tunable Genetic Switch Behavior: A Mathematical Modeling Approach.

    Science.gov (United States)

    Bordoy, Antoni E; Chatterjee, Anushree

    2015-01-01

    Antisense transcription has been extensively recognized as a regulatory mechanism for gene expression across all kingdoms of life. Despite the broad importance and extensive experimental determination of cis-antisense transcription, relatively little is known about its role in controlling cellular switching responses. Growing evidence suggests the presence of non-coding cis-antisense RNAs that regulate gene expression via antisense interaction. Recent studies also indicate the role of transcriptional interference in regulating expression of neighboring genes due to traffic of RNA polymerases from adjacent promoter regions. Previous models investigate these mechanisms independently, however, little is understood about how cells utilize coupling of these mechanisms in advantageous ways that could also be used to design novel synthetic genetic devices. Here, we present a mathematical modeling framework for antisense transcription that combines the effects of both transcriptional interference and cis-antisense regulation. We demonstrate the tunability of transcriptional interference through various parameters, and that coupling of transcriptional interference with cis-antisense RNA interaction gives rise to hypersensitive switches in expression of both antisense genes. When implementing additional positive and negative feed-back loops from proteins encoded by these genes, the system response acquires a bistable behavior. Our model shows that combining these multiple-levels of regulation allows fine-tuning of system parameters to give rise to a highly tunable output, ranging from a simple-first order response to biologically complex higher-order response such as tunable bistable switch. We identify important parameters affecting the cellular switch response in order to provide the design principles for tunable gene expression using antisense transcription. This presents an important insight into functional role of antisense transcription and its importance towards

  13. Three-year summary report of biological monitoring at the Southwest Ocean dredged-material disposal site and additional locations off Grays Harbor, Washington, 1990--1992

    Energy Technology Data Exchange (ETDEWEB)

    Antrim, L.D.; Shreffler, D.K.; Pearson, W.H.; Cullinan, V.I. [Battelle Marine Research Lab., Sequim, WA (United States)

    1992-12-01

    The Grays Harbor Navigation Improvement Project was initiated to improve navigation by widening and deepening the federal channel at Grays Harbor. Dredged-material disposal sites were selected after an extensive review process that included inter-agency agreements, biological surveys, other laboratory and field studies, and preparation of environmental impact statements The Southwest Site, was designated to receive materials dredged during annual maintenance dredging as well as the initial construction phase of the project. The Southwest Site was located, and the disposal operations designed, primarily to avoid impacts to Dungeness crab. The Final Environmental Impact Statement Supplement for the project incorporated a Site Monitoring Plan in which a tiered approach to disposal site monitoring was recommended. Under Tier I of the Site Monitoring Plan, Dungeness crab densities are monitored to confirm that large aggregations of newly settled Dungeness crab have not moved onto the Southwest Site. Tier 2 entails an increased sampling effort to determine whether a change in disposal operations is needed. Four epibenthic surveys using beam trawls were conducted in 1990, 1991, and 1992 at the Southwest Site and North Reference area, where high crab concentrations were found in the spring of 1985. Survey results during these three years prompted no Tier 2 activities. Epibenthic surveys were also conducted at two nearshore sites where construction of sediment berms has been proposed. This work is summarized in an appendix to this report.

  14. Low-loss tunable all-in-fiber filter for Raman spectroscopy

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Scolari, Lara; Lund-Hansen, Toke;

    2011-01-01

    We show a novel in-line Rayleigh-rejection filter for Raman spectroscopy, based on a solid-core Photonic Crystal Fiber (PCF) filled with a high-index material. The device is low-loss and thermally tunable, and allows for a strong attenuation of the Rayleigh line at 532nm and the transmission...... of the Raman lines in a broad wavenumber range....

  15. Highly tunable hybrid metamaterials employing split-ring resonators strongly coupled to graphene surface plasmons

    OpenAIRE

    Liu, Peter Q.; Luxmoore, Isaac. J.; Mikhailov, Sergey A.; Savostianova, Nadja A.; Valmorra, Federico; Faist, Jérôme; Nash, Geoffrey R.

    2015-01-01

    Metamaterials and plasmonics are powerful tools for unconventional manipulation and harnessing of light. Metamaterials can be engineered to possess intriguing properties lacking in natural materials, such as negative refractive index. Plasmonics offers capabilities of confining light in subwavelength dimensions and enhancing light–matter interactions. Recently, the technological potential of graphene-based plasmonics has been recognized as the latter features large tunability, higher field-co...

  16. Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application

    OpenAIRE

    Goutam Kumar Dalapati; Saeid Masudy-Panah; Sing Teng Chua; Mohit Sharma; Ten It Wong; Hui Ru Tan; Dongzhi Chi

    2016-01-01

    Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process opt...

  17. A Tunable Carbon Nanotube Oscillator

    Science.gov (United States)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  18. Tunable Oscillations in the Purkinje Neuron

    CERN Document Server

    Abrams, Ze'ev R; Wang, Yuan; Trauner, Dirk; Zhang, Xiang

    2011-01-01

    In this paper, we study the dynamics of slow oscillations in Purkinje neurons in vitro, and derive a strong association with a forced parametric oscillator model. We demonstrate the precise rhythmicity of the oscillations in Purkinje neurons, as well as a dynamic tunability of this oscillation using a photo-switchable compound. We show that this slow oscillation can be induced in every Purkinje neuron, having periods ranging between 10-25 seconds. Starting from a Hodgkin-Huxley model, we also demonstrate that this oscillation can be externally modulated, and that the neurons will return to their intrinsic firing frequency after the forced oscillation is concluded. These results signify an additional functional role of tunable oscillations within the cerebellum, as well as a dynamic control of a time scale in the brain in the range of seconds.

  19. Thermally tunable quadruple Vernier racetrack resonators.

    Science.gov (United States)

    Boeck, Robert; Chrostowski, Lukas; Jaeger, Nicolas A F

    2013-07-15

    The spectral responses of series-coupled racetrack resonators exhibiting the Vernier effect have many attractive features as compared to the spectral responses of identical series-coupled racetrack resonators, such as free spectral range (FSR) extension and enhanced wavelength tunability. Here we present experimental results of a thermally tunable quadruple series-coupled silicon racetrack resonator exhibiting the Vernier effect. We thermally tune two of the four racetrack resonators to enable discrete switching of the major peak by 15.54 nm. Also, our device has an interstitial peak suppression of 35.4 dB, a 3 dB bandwidth of 0.45 nm, and an extended FSR of 37.66 nm.

  20. Bacteriorhodopsin: Tunable Optical Nonlinear Magnetic Response

    CERN Document Server

    Bovino, F A; Sibilia, C; Giardina, M; Váró, G; Gergely, C

    2011-01-01

    We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) under "off resonance" femtosecond (fs) pulse excitation, by detecting the polarization map of the noncollinear second harmonic signal of an oriented BR film, as a function of the input beam power. BR is a light-driven proton pump with a unique photochemistry initiated by the all trans retinal chromophore embedded in the protein. An elegant application of this photonic molecular machine has been recently found in the new area of optogenetics, where genetic expression of BR in brain cells conferred a light responsivity to the cells enabling thus specific stimulation of neurons. The observed strong tunable magnetic nonlinear response of BR might trigger promising applications in the emerging area of pairing optogenetics and functional magnetic resonance imaging susceptible to provide an unprecedented complete functional mapping of neural circuits.

  1. 130-nm tunable grating-mirror VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2014-01-01

    We have reported that a combination of the high-index-contrast grating (HCG) mirror as movable mirror and the extended cavity configuration with an antireflection layer can provide a tuning wavelength range of 100 nm for tunable VCSELs. Here, we report that using the air-coupled cavity configurat......We have reported that a combination of the high-index-contrast grating (HCG) mirror as movable mirror and the extended cavity configuration with an antireflection layer can provide a tuning wavelength range of 100 nm for tunable VCSELs. Here, we report that using the air-coupled cavity...... configuration instead of the extended cavity configuration can bring 130-nm tuning range around 1330-nm wavelength. The air-coupled cavity is known to reduce the quantum confinement factor in VCSELs, increasing threshold. In our air-coupled cavity HCG VCSEL case, the very short power penetration length...

  2. Tunable plasmonic metasurface for perfect absorption

    Directory of Open Access Journals (Sweden)

    Arroyo Huidobro Paloma

    2017-01-01

    Full Text Available Tunable metasurfaces, whose functionality can be dynamically modified, open up the possibility of ultra-compact photonic components with reconfigurable applications. Here we consider a graphene monolayer subject to a spatially periodic gate bias, which, thank to surface plasmons in the graphene, acts as a tunable and extremely compact metasurface for terahertz radiation. After characterizing its functionality, we show that it serves as the basic building block of an ultrathin complete absorber. In this subwavelength-thickness device, transmission and reflection channels are blocked and electromagnetic energy is completely absorbed by the metasurface building blocks. The proposed structure can be used as a modulator, and its frequency of operation can be changed by scaling its size or adjusting the doping level.

  3. Three Dimensional Broadband Tunable Terahertz Metamaterials

    CERN Document Server

    Fan, Kebin; Zhang, Xin; Averitt, Richard D

    2013-01-01

    We present optically tunable magnetic 3D metamaterials at terahertz (THz) frequencies which exhibit a tuning range of ~30% of the resonance frequency. This is accomplished by fabricating 3D array structures consisting of double-split-ring resonators (DSRRs) on silicon-on-sapphire, fabricated using multilayer electroplating. Photoexcitation of free carriers in the silicon within the capacitive region of the DSRR results in a red-shift of the resonant frequency from 1.74 THz to 1.16 THz. The observed frequency shift leads to a transition from a magnetic-to-bianisotropic response as verified through electromagnetic simulations and parameter retrieval. Our approach extends dynamic metamaterial tuning to magnetic control, and may find applications in switching and modulation, polarization control, or tunable perfect absorbers.

  4. Dangers resulting from DNA profiling of biological materials derived from patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT) with regard to forensic genetic analysis.

    Science.gov (United States)

    Jacewicz, R; Lewandowski, K; Rupa-Matysek, J; Jędrzejczyk, M; Berent, J

    2015-01-01

    The study documents the risk that comes with DNA analysis of materials derived from patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in forensic genetics. DNA chimerism was studied in 30 patients after allo-HSCT, based on techniques applied in contemporary forensic genetics, i.e. real-time PCR and multiplex PCR-STR with the use of autosomal DNA as well as Y-DNA markers. The results revealed that the DNA profile of the recipient's blood was identical with the donor's in the majority of cases. Therefore, blood analysis can lead to false conclusions in personal identification as well as kinship analysis. An investigation of buccal swabs revealed a mixture of DNA in the majority of recipients. Consequently, personal identification on the basis of stain analysis of the same origin may be impossible. The safest (but not ideal) material turned out to be the hair root. Its analysis based on autosomal DNA revealed 100% of the recipient's profile. However, an analysis based on Y-chromosome markers performed in female allo-HSCT recipients with male donors demonstrated the presence of donor DNA in hair cells - similarly to the blood and buccal swabs. In the light of potential risks arising from DNA profiling of biological materials derived from persons after allotransplantation in judicial aspects, certain procedures were proposed to eliminate such dangers. The basic procedures include abandoning the approach based exclusively on blood collection, both for kinship analysis and personal identification; asking persons who are to be tested about their history of allo-HSCT before sample collection and profile entry in the DNA database, and verification of DNA profiling based on hair follicles in uncertain cases.

  5. Dangers resulting from DNA profiling of biological materials derived from patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT with regard to forensic genetic analysis

    Directory of Open Access Journals (Sweden)

    Renata Jacewicz

    2016-07-01

    Full Text Available The study documents the risk that comes with DNA analysis of materials derived from patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT in forensic genetics. DNA chimerism was studied in 30 patients after allo-HSCT, based on techniques applied in contemporary forensic genetics, i.e. real-time PCR and multiplex PCR-STR with the use of autosomal DNA as well as Y-DNA markers. The results revealed that the DNA profile of the recipient’s blood was identical with the donor’s in the majority of cases. Therefore, blood analysis can lead to false conclusions in personal identification as well as kinship analysis. An investigation of buccal swabs revealed a mixture of DNA in the majority of recipients. Consequently, personal identification on the basis of stain analysis of the same origin may be impossible. The safest (but not ideal material turned out to be the hair root. Its analysis based on autosomal DNA revealed 100% of the recipient’s profile. However, an analysis based on Y-chromosome markers performed in female allo-HSCT recipients with male donors demonstrated the presence of donor DNA in hair cells – similarly to the blood and buccal swabs. In the light of potential risks arising from DNA profiling of biological materials derived from persons after allotransplantation in judicial aspects, certain procedures were proposed to eliminate such dangers. The basic procedures include abandoning the approach based exclusively on blood collection, both for kinship analysis and personal identification; asking persons who are to be tested about their history of allo-HSCT before sample collection and profile entry in the DNA database, and verification of DNA profiling based on hair follicles in uncertain cases.

  6. Tunable coplanar waveguide resonator with nanowires

    Institute of Scientific and Technical Information of China (English)

    周渝; 郏涛; 翟计全; 汪橙; 钟先茜; 曹志敏; 孙国柱; 康琳; 吴培亨

    2015-01-01

    A tunable superconducting half-wavelength coplanar waveguide resonator (CPWR) with Nb parallel nanowires ∼300 nm in width embedded in the center conductor was designed, fabricated, and measured. The frequency shift and the amplitude attenuation of the resonance peak under irradiation of 404-nm pulse laser were observed with different light powers at 4.2 K. The RF power supplied to such a CPWR can serve as current bias, which will affect the light response of the resonator.

  7. Tunable Focusing by a Flexible Metasurface

    CERN Document Server

    Zárate, Yair; Powell, David A

    2016-01-01

    An efficient reflective elastic metasurface with tunable focusing point is proposed. The metasurface is based on electric resonators embedded in a stretchable elastic substrate. The focal length is controlled by mean of the stretching applied applied to the sample. The results predicted by theory and numerical simulations are experimentally verified. Our proposal shows that smart engineering elastic metamaterials are an effective platform for new functional devices based on metamaterials.

  8. Rugged, Tunable Extended-Cavity Diode Laser

    Science.gov (United States)

    Moore, Donald; Brinza, David; Seidel, David; Klipstein, William; Choi, Dong Ho; Le, Lam; Zhang, Guangzhi; Iniguez, Roberto; Tang, Wade

    2007-01-01

    A rugged, tunable extended-cavity diode laser (ECDL) has been developed to satisfy stringent requirements for frequency stability, notably including low sensitivity to vibration. This laser is designed specifically for use in an atomic-clock experiment to be performed aboard the International Space Station (ISS). Lasers of similar design would be suitable for use in terrestrial laboratories engaged in atomic-clock and atomic-physics research.

  9. Green synthesis of biocompatible gold nanocrystals with tunable surface plasmon resonance using garlic phytochemicals.

    Science.gov (United States)

    Menon, Deepthy; Basanth, Amritha; Retnakumari, Archana; Manzoor, K; Nair, Shantikumar V

    2012-12-01

    Synthesis of biocompatible gold nanoparticles having tunable optical absorbance finds immense use in biomedical applications such as cancer diagnosis and photothermal therapy. Hence, it is imperative to develop environment and bio-friendly green chemical processes that aid in preparing gold nanoparticles with tunable optical properties. In the present work, phytochemicals present in the medicinal herb, viz., garlic, were used to provide the dual effects of reduction of gold salts to gold nanoparticles as well as stabilization, in a single step process. The optical tunability of nanogold with respect to concentration of precursor and volume of garlic extract, processing conditions of garlic, its differing molecular weight fractions, reaction time and temperature has been demonstrated. The presence of a range of anisotropic nanogold including nanotriangles, nanorods and nanospheres as evident from TEM endows the colloid with a tunable optical absorption, specifically into the near infrared region. In vitro stability studies of the colloidal suspension in various media including saline, BSA, histidine and PBS showed that gold nanoparticles did not aggregate with time or differing pH conditions. The role of the garlic phytochemicals in providing stability against agglomeration was also substantiated by FTIR studies. Cytotoxicity studies performed using spherical and anisotropic gold nanoparticles on MCF-7 and L929 cell lines proved the biocompatibility of the material up to high doses of 500 microg/ml. The present work highlights the role of garlic phytochemicals in preparing biocompatible metallic gold nanoparticles with tunable optical properties and good in vitro stability, suggesting its potential use for molecular imaging or therapeutic nanomedicines.

  10. Ultrafast tunable chirped phase-change metamaterial with a low power.

    Science.gov (United States)

    Cao, Tun; Wei, Chenwei; Mao, Libang

    2015-02-23

    We numerically demonstrate an all-optical tunable dual-band double negative (DNG) index chirped metamaterial (MM) in the mid-infrared (M-IR) region. This MM possesses an ultrafast and significant tunability under low pump light power, realized by combining phase change material (PCM). It has a configuration of elliptical nanohole array (ENA) penetrating through metal/PCM/metal (Au-Ge(2)Sb(2)Te(5)-Au) films. Here, we consider the case when the chirp is introduced by displacing the positions of the ENA along the short axis of the elliptical apertures inside the primitive cell, which can achieve multiple internal surface-plasmon polariton (SPP) modes at the inner metal-dielectric interfaces of the structure and thus providing a dual-band negative index with simultaneous negative permittivity and permeability. The influence of amorphous and crystalline states of Ge(2)Sb(2)Te(5) on the effective optical parameters of the structure is analyzed. Switching between these states provides a large wavelength shift of the structure's effective optical parameters. A photothermal model is used to study the temporal variation of the temperature of the Ge(2)Sb(2)Te(5) layer to show a potential to switch the phase of Ge(2)Sb(2)Te(5) by optical heating. Generation of the tunable dual-band DNG index presents clear advantages as it possesses a fast tuning time of 0.4 ns, a low pump light intensity of 7.3μW/μm(2), and a large tunable wavelength range of 978 nm. We expect that our design may have potential applications in actively tunable multi-band nanodevices.

  11. Metal-organic frameworks as sensory materials and imaging agents.

    Science.gov (United States)

    Liu, Demin; Lu, Kuangda; Poon, Christopher; Lin, Wenbin

    2014-02-17

    Metal-organic frameworks (MOFs) are a class of hybrid materials self-assembled from organic bridging ligands and metal ion/cluster connecting points. The combination of a variety of organic linkers, metal ions/clusters, and structural motifs can lead to an infinite array of new materials with interesting properties for many applications. In this Forum Article, we discuss the design and applications of MOFs in chemical sensing and biological imaging. The first half of this article focuses on the development of MOFs as chemical sensors by highlighting how unique attributes of MOFs can be utilized to enhance sensitivity and selectivity. We also discuss some of the issues that need to be addressed in order to develop practically useful MOF sensors. The second half of this article focuses on the design and applications of nanoscale MOFs (NMOFs) as imaging contrast agents. NMOFs possess several interesting attributes, such as high cargo loading capacity, ease of postmodification, tunable size and shape, and intrinsic biodegradability, to make them excellent candidates as imaging contrast agents. We discuss the use of representative NMOFs in magnetic resonance imaging (MRI), X-ray computed tomography (CT), and optical imaging. Although still in their infancy, we believe that the compositional tunability and mild synthetic conditions of NMOF imaging agents should greatly facilitate their further development for clinical translation.

  12. A Continuously Tunable Erbium-Doped Fibre Laser Using Tunable Fibre Bragg Gratings and Optical Circulator

    Science.gov (United States)

    Liu, Peng; Yan, Feng-Ping; Li, Jian; Wang, Lin; Ning, Ti-Gang; Gong, Tao-Rong; Jian, Shui-Sheng

    2008-12-01

    A continuously tunable erbium-doped fibre laser (TEDFL) based on tunable fibre Bragger grating (TFBG) and a three-port optical circulator (OC) is proposed and demonstrated. The OC acts as a 100%-reflective mirror. A strain-induced uniform fibre Bragger grating (FBG) which functions as a partial-reflecting mirror is implemented in the linear cavity. By applying axial strain onto the TFBG, a continuously tunable lasing output can be realized. The wavelength tuning range covers approximately 7.00nm in C band (from 1543.6161 to 1550.3307nm). The side mode suppression ratio (SMSR) is better than 50 dB, and the 3 dB bandwidth of the laser is less than 0.01 nm. Moreover, an array waveguide grating (AWG) is inserted into the cavity for wavelength preselecting, and a 50 km transmission experiment was performed using our TEDFL at a 10Gb/s modulation rate.

  13. Tunable bandpass filter based on partially magnetized ferrite LTCC with embedded windings for SoP applications

    KAUST Repository

    Arabi, Eyad A.

    2015-01-01

    Tunable filters that are based on ferrite materials often require large and bulky electromagnets. In this work, we present a tunable filter in the Ku-band, which is realized in multilayer ferrite LTCC substrate with embedded bias windings, thus negating the need of a large electromagnet. Also, because of the embedded windings, the bias fields are not lost at the air-substrate interface and therefore the field and current requirements are reduced by an order of magnitude as compared to the previously reported filters. A simulation strategy that uses full permeability tensor with arbitrarily directed magnetic fields has been used to model the filter on a partially magnetized ferrite substrate. Special attention has also been paid to approximate the non-uniform magneto-static fields produced by the embedded windings. The complete design is implemented in 10 layers of ferrite LTCC, making it the first magnetically tunable filter with embedded windings and extremely small size [(5 × 5 × 1.1)mm3]. The filter demonstrates a measured tunability of 4% and an insertion loss of 2.3 dB. With the small form factor, embedded windings, and low bias requirements, the design is highly suitable for compact and tunable SoP applications.

  14. Final Report of “Collaborative research: Fundamental science of low temperature plasma-biological material interactions” (Award# DE-SC0005105)

    Energy Technology Data Exchange (ETDEWEB)

    Oehrlein, Gottlieb S. [Univ. of Maryland, College Park, MD (United States); Seog, Joonil [Univ. of Maryland, College Park, MD (United States); Graves, David [Univ. of California, Berkeley, CA (United States); Chu, J. -W. [Univ. of California, Berkeley, CA (United States)

    2014-09-24

    temperature plasma sources with modified geometry where radical induced interactions generally dominate due to short mean free paths of ions and VUV photons. In these conditions we demonstrated the importance of environmental interactions of plasma species when APP sources are used to modify biomolecules. This is evident from both gas phase characterization data and in-situ surface characterization of treated biomolecules. Environmental interactions can produce unexpected outcomes due to the complex reactions of reactive species with the atmosphere which determine the composition of reactive fluxes and atomistic changes in biomolecules. Overall, this work elucidated a richer spectrum of scientific opportunities and challenges for the field of low temperature plasma-biomolecule surface interactions than initially anticipated, in particular, for plasma sources operating at atmospheric pressure. The insights produced in this work, e.g. demonstration of the importance of environmental interactions, are generally important for applications of APP to materials modifications. Thus one major contributions of this research has been the establishment of methodologies to study the interaction of plasma with bio-molecules in a systemic and rigorous manner. In particular, our studies of atmospheric pressure plasma sources using very well-defined experimental conditions enabled us to correlate atomistic surface modifications of biomolecules with changes in their biological function. The clarification of the role of ions, VUV photons and radicals in deactivation of biomolecules during low pressure and atmospheric pressure plasma-biomolecule interaction has broad implications, e.g. for the emerging field of plasma medicine. The development of methods to detect the effects of plasma treatment on immune-active biomolecules will lay a fundamental foundation to enhance our understanding of the effect of plasma on biological systems. be helpful in many future studies.

  15. Tunable nonlinear superconducting metamaterials: Experiment and simulation

    Science.gov (United States)

    Trepanier, Melissa

    I present experimental and numerical simulation results for two types of nonlinear tunable superconducting metamaterials: 2D arrays of rf SQUIDs (radio frequency superconducting quantum interference devices) as magnetic metamaterials and arrays of Josephson junction-loaded wires as electric metamaterials. The effective inductance of a Josephson junction is sensitive to dc current, temperature, and rf current. I took advantage of this property to design arrays of Josephson junction-loaded wires that present a tunable cutoff frequency and thus a tunable effective permittivity for propagating electromagnetic waves in a one-conductor waveguide. I measured the response of the metamaterial to each tuning parameter and found agreement with numerical simulations that employ the RCSJ (resistively and capacitively shunted junction) model. An rf SQUID is an analogue of an SRR (split ring resonator) with the gap capacitance replaced with a Josephson junction. Like the SRR the SQUID is a resonant structure with a frequency-dependent effective permeability. The difference between the SQUID and the SRR is that the effective inductance and thus effective permeability of the SQUID can be tuned with dc and rf flux, and temperature. Individual rf SQUID meta-atoms and two-dimensional arrays were designed and measured as a function of each tuning parameter and I have found excellent agreement with numerical simulations. There is also an interesting transparency feature that occurs for intermediate rf flux values. The tuning of SQUID arrays has a similar character to the tuning of individual rf SQUID meta-atoms. However, I found that the coupling between the SQUIDs increases the resonant frequency, decreases dc flux tuning, and introduces additional resonant modes. Another feature of arrays is disorder which suppresses the coherence of the response and negatively impacts the emergent properties of the metamaterial. The disorder was experimentally found to be mainly due to a dc flux

  16. Modeling growth in biological materials

    OpenAIRE

    Jones, Gareth Wyn; Chapman, S. Jonathan

    2012-01-01

    The biomechanical modeling of growing tissues has recently become an area of intense interest. In particular, the interplay between growth patterns and mechanical stress is of great importance, with possible applications to arterial mechanics, embryo morphogenesis, tumor development, and bone remodeling. This review aims to give an overview of the theories that have been used to model these phenomena, categorized according to whether the tissue is considered as a continuum object or a collect...

  17. Tunable spin polarization and superconductivity in engineered oxide interfaces

    Science.gov (United States)

    Stornaiuolo, D.; Cantoni, C.; de Luca, G. M.; di Capua, R.; di. Gennaro, E.; Ghiringhelli, G.; Jouault, B.; Marrè, D.; Massarotti, D.; Miletto Granozio, F.; Pallecchi, I.; Piamonteze, C.; Rusponi, S.; Tafuri, F.; Salluzzo, M.

    2016-03-01

    Advances in growth technology of oxide materials allow single atomic layer control of heterostructures. In particular delta doping, a key materials' engineering tool in today's semiconductor technology, is now also available for oxides. Here we show that a fully electric-field-tunable spin-polarized and superconducting quasi-2D electron system (q2DES) can be artificially created by inserting a few unit cells of delta doping EuTiO3 at the interface between LaAlO3 and SrTiO3 oxides. Spin polarization emerges below the ferromagnetic transition temperature of the EuTiO3 layer (TFM = 6-8 K) and is due to the exchange interaction between the magnetic moments of Eu-4f and of Ti-3d electrons. Moreover, in a large region of the phase diagram, superconductivity sets in from a ferromagnetic normal state. The occurrence of magnetic interactions, superconductivity and spin-orbit coupling in the same q2DES makes the LaAlO3/EuTiO3/SrTiO3 system an intriguing platform for the emergence of novel quantum phases in low-dimensional materials.

  18. Tunable spin polarization and superconductivity in engineered oxide interfaces.

    Science.gov (United States)

    Stornaiuolo, D; Cantoni, C; De Luca, G M; Di Capua, R; Di Gennaro, E; Ghiringhelli, G; Jouault, B; Marrè, D; Massarotti, D; Miletto Granozio, F; Pallecchi, I; Piamonteze, C; Rusponi, S; Tafuri, F; Salluzzo, M

    2016-03-01

    Advances in growth technology of oxide materials allow single atomic layer control of heterostructures. In particular delta doping, a key materials' engineering tool in today's semiconductor technology, is now also available for oxides. Here we show that a fully electric-field-tunable spin-polarized and superconducting quasi-2D electron system (q2DES) can be artificially created by inserting a few unit cells of delta doping EuTiO3 at the interface between LaAlO3 and SrTiO3 oxides. Spin polarization emerges below the ferromagnetic transition temperature of the EuTiO3 layer (TFM = 6-8 K) and is due to the exchange interaction between the magnetic moments of Eu-4f and of Ti-3d electrons. Moreover, in a large region of the phase diagram, superconductivity sets in from a ferromagnetic normal state. The occurrence of magnetic interactions, superconductivity and spin-orbit coupling in the same q2DES makes the LaAlO3/EuTiO3/SrTiO3 system an intriguing platform for the emergence of novel quantum phases in low-dimensional materials.

  19. tCRISPRi: tunable and reversible, one-step control of gene expression

    Science.gov (United States)

    Li, Xin-Tian; Jun, Yonggun; Erickstad, Michael J.; Brown, Steven D.; Parks, Adam; Court, Donald L.; Jun, Suckjoon

    2016-12-01

    The ability to control the level of gene expression is a major quest in biology. A widely used approach employs deletion of a nonessential gene of interest (knockout), or multi-step recombineering to move a gene of interest under a repressible promoter (knockdown). However, these genetic methods are laborious, and limited for quantitative study. Here, we report a tunable CRISPR-cas system, “tCRISPRi”, for precise and continuous titration of gene expression by more than 30-fold. Our tCRISPRi system employs various previous advancements into a single strain: (1) We constructed a new strain containing a tunable arabinose operon promoter PBAD to quantitatively control the expression of CRISPR-(d)Cas protein over two orders of magnitude in a plasmid-free system. (2) tCRISPRi is reversible, and gene expression is repressed under knockdown conditions. (3) tCRISPRi shows significantly less than 10% leaky expression. (4) Most important from a practical perspective, construction of tCRISPRi to target a new gene requires only one-step of oligo recombineering. Our results show that tCRISPRi, in combination with recombineering, provides a simple and easy-to-implement tool for gene expression control, and is ideally suited for construction of both individual strains and high-throughput tunable knockdown libraries.

  20. Polymer lattices as mechanically tunable 3-dimensional photonic crystals operating in the infrared

    Energy Technology Data Exchange (ETDEWEB)

    Chernow, V. F., E-mail: vchernow@caltech.edu [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Alaeian, H. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Dionne, J. A. [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Greer, J. R. [Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California 91125 (United States); The Kavli Nanoscience Institute, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-09-07

    Broadly tunable photonic crystals in the near- to mid-infrared region could find use in spectroscopy, non-invasive medical diagnosis, chemical and biological sensing, and military applications, but so far have not been widely realized. We report the fabrication and characterization of three-dimensional tunable photonic crystals composed of polymer nanolattices with an octahedron unit-cell geometry. These photonic crystals exhibit a strong peak in reflection in the mid-infrared that shifts substantially and reversibly with application of compressive uniaxial strain. A strain of ∼40% results in a 2.2 μm wavelength shift in the pseudo-stop band, from 7.3 μm for the as-fabricated nanolattice to 5.1 μm when strained. We found a linear relationship between the overall compressive strain in the photonic crystal and the resulting stopband shift, with a ∼50 nm blueshift in the reflection peak position per percent increase in strain. These results suggest that architected nanolattices can serve as efficient three-dimensional mechanically tunable photonic crystals, providing a foundation for new opto-mechanical components and devices across infrared and possibly visible frequencies.

  1. [The validation of kit of reagents for quantitative detection of DNA of human cytomegalovirus in biological material using polymerase chain reaction technique in real time operation mode].

    Science.gov (United States)

    Sil'veĭstrova, O Iu; Domonova, É A; Shipulina, O Iu

    2014-04-01

    The validation of kit of reagents destined to detection and quantitative evaluation of DNA of human cytomegalovirus in biological material using polymerase chain reaction technique in real time operation mode was implemented. The comparison was made against international WHO standard--The first WHO international standard for human cytomegalovirus to implement measures the kit of reagents "AmpliSens CMV-screen/monitor-FL" and standard sample of enterprise DNA HCMV (The central research institute of epidemiology of Rospotrebnadzor) was applied. The fivefold dilution of international WHO standard and standard sample of enterprise were carried out in concentrations of DNA HCMV from 106 to 102. The arrangement of polymerase chain reaction and analysis of results were implemented using programed amplifier with system of detection of fluorescent signal in real-time mode "Rotor-Gene Q" ("Qiagen", Germany). In the total of three series of experiments, all stages of polymerase chain reaction study included, the coefficient of translation of quantitative evaluation of DNA HCMV from copy/ml to ME/ml equal to 0.6 was introduced for this kit of reagents.

  2. Organomercury determination in biological reference materials: application to a study on mercury speciation in marine mammals off the Faröe Islands.

    Science.gov (United States)

    Schintu, M; Jean-Caurant, F; Amiard, J C

    1992-08-01

    The potential use of graphite furnace atomic absorption spectrometry (GF-AAS) for the organic mercury determination in marine biological tissues was evaluated. Following its isolation by acid extraction in toluene, organic mercury was recovered in aqueous thiosulfate and measured by GF-AAS. The detection limit was 0.01 microgram Hg/g (as methyl mercury). Analyses were conducted on three reference standard materials certified for their methyl mercury content, DOLT-1, DORM-1, and TORT-1, provided by the National Research Council of Canada. The method resulted in very good recovery and reproducibility, indicating that GF-AAS can provide results comparable to those obtained by using more expensive and time consuming analytical techniques. The method was applied to the analysis of liver tissues of pilot whale specimens (Globicephala melas) from the drive fishery of the Faröe Islands (northeast Atlantic). The results provided useful information on the proportion of different mercury forms in the liver of these marine mammals.

  3. Combinational pixel-by-pixel and object-level classifying, segmenting, and agglomerating in performing quantitative image analysis that distinguishes between healthy non-cancerous and cancerous cell nuclei and delineates nuclear, cytoplasm, and stromal material objects from stained biological tissue materials

    Science.gov (United States)

    Boucheron, Laura E

    2013-07-16

    Quantitative object and spatial arrangement-level analysis of tissue are detailed using expert (pathologist) input to guide the classification process. A two-step method is disclosed for imaging tissue, by classifying one or more biological materials, e.g. nuclei, cytoplasm, and stroma, in the tissue into one or more identified classes on a pixel-by-pixel basis, and segmenting the identified classes to agglomerate one or more sets of identified pixels into segmented regions. Typically, the one or more biological materials comprises nuclear material, cytoplasm material, and stromal material. The method further allows a user to markup the image subsequent to the classification to re-classify said materials. The markup is performed via a graphic user interface to edit designated regions in the image.

  4. Tailored single-walled carbon nanotube--CdS nanoparticle hybrids for tunable optoelectronic devices.

    Science.gov (United States)

    Li, Xianglong; Jia, Yi; Cao, Anyuan

    2010-01-26

    The integration of organic and inorganic building blocks into novel nanohybrids is an important tool to exploit innovative materials with desirable functionalities. For this purpose, carbon nanotube--nanoparticle nanoarchitectures are intensively studied. We report here an efficient noncovalent chemical route to density-controllably and uniformly assemble single-walled carbon nanotubes with CdS nanoparticles. The methodology not only promises the resulting hybrids will be solution-processable but also endows the hybrids with distinct optoelectronic properties including tunable photoresponse mediated by amine molecules. On the basis of these merits, reliable thin-film photoswitches and light-driven chemical sensors are demonstrated, which highlights the potential of tailored hybrids in the development of new tunable optoelectronic devices and sensors.

  5. Tunable diffraction grating in flexible substrate by UV-nanoimprint lithography

    Science.gov (United States)

    Hamouda, F.; Aassime, A.; Bertin, H.; Gogol, P.; Bartenlian, B.; Dagens, B.

    2017-02-01

    The fabrication of flexible advanced devices is a very important issue that requires the hybrid integration of different nanostructured materials. In this work, we report on a new molding technique based on an improved hard UV-nanoimprint lithography process (hard UV-NIL) using a poly(dimethylsiloxane) (PDMS) film. The large-scale integration of a high-quality nanostructured gold pattern in PDMS is made possible with the use of an inorganic sacrificial layer soluble in hydrogen peroxide. A tunable diffraction gold stripe grating has been fabricated by transferring a 1 cm2 stripe grating from a rigid silicon substrate to a flexible PDMS substrate. As a result, we successfully demonstrate diffraction grating optical tunability when mechanical tension is applied.

  6. Biocompatible Single-Crystal Selenium Nanobelt Based Nanodevice as a Temperature-Tunable Photosensor

    Directory of Open Access Journals (Sweden)

    Yongshan Niu

    2012-01-01

    Full Text Available Selenium materials are widely used in photoelectrical devices, owing to their unique semiconductive properties. Single-crystal selenium nanobelts with large specific surface area, fine photoconductivity, and biocompatibility provide potential applications in biomedical nanodevices, such as implantable artificial retina and rapid photon detector/stimulator for optogenetics. Here, we present a selenium nanobelt based nanodevice, which is fabricated with single Se nanobelt. This device shows a rapid photo response, different sensitivities to visible light of variable wave length, and temperature-tunable property. The biocompatibility of the Se nanobelts was proved by MTT test using two cell lines. Our investigation introduced a photosensor that will be important for multiple potential applications in human visual system, photocells in energy or MEMS, and temperature-tunable photoelectrical device for optogenetics research.

  7. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.

    2015-06-23

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  8. A planar and tunable bandpass filter on a ferrite substrate with integrated windings

    KAUST Repository

    Arabi, Eyad A.

    2015-05-01

    Tunable Filters that are based on ferrite materials are often biased by external magnets or coils which are large and bulky. In this work a completely planar, CPW-based bandpass filter is presented with integrated windings. Due to these windings the size of the filter is only 26mm × 34mm × 0.38mm which is orders of magnitude smaller than the traditional designs with external windings. The filter is realized by electroplating of Copper over seed layers of Titanium and Gold over a YIG substrate. The fabricated filter achieves a tunability of 3.4% without any external magnets or coils. A good insertion loss of 2.3 dBs and rejection greater than 50 dBs have been obtained. To the best of the authors knowledge, this design is the first ferrite-based design that is completely planar and self-biased.

  9. Desarrollo de un Simulador de Secado para Materiales Biológicos Development of a Simulation Model for Drying Biological Materials

    Directory of Open Access Journals (Sweden)

    R. Olivas-Vargas

    2004-01-01

    Full Text Available En este artículo, se proponen dos modelos para describir el proceso de secado y el deterioro que ocurre en el procesamiento de materiales biológicos, partiendo de datos experimentales. El estudio fue desarrollado utilizando chile jalapeño (Capsicum annuum L. y manzana en rebanadas como materias primas. El deterioro fue evaluado mediante cambio en la capacidad de rehidratación en chile jalapeño y cambios en el color en manzana. El modelo de secado propuesto se utilizó con las ecuaciones clásicas usadas en esta operación unitaria para predecir el tiempo de proceso. Tomando estos modelos, se desarrolló un software de análisis y predicción de los balances de masa y energía, como una herramienta de utilidad en el escalamiento o diseño de sistemas de secado, así como el daño que el material va a sufrir. El software desarrollado tuvo un excelente desempeño en materiales que muestran poca dispersión de los datos experimentalesTwo models, based on experimental data, that describe the process of drying and the deterioration that occurs during the processing of biological materials, are proposed in this article. Jalapeño pepper (Capsicum annuum L. and apple slices were used for generation of experimental data. Rehydration capability on jalapeño pepper and color changes on apple slices were used for measurement of deterioration. The proposed drying model was used with the classic equations this unit operation to predict the processing time. Based on these models, a computer program for the analysis and prediction of the mass and energy balances was developed as a useful tool in the scaling or design of the drying systems, as well as the damage that the material will suffer. The software developed showed an excellent performance when experimental data have low dispersion

  10. Tunable Soft X-Ray Oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wurtele, Jonathan; Gandhi, Punut; Gu, X-W; Fawley, William M; Reinsch, Matthia; Penn, Gregory; Kim, K-J; Lindberg, Ryan; Zholents, Alexander

    2010-09-17

    A concept for a tunable soft x-ray free electron laser (FEL) photon source is presented and studied numerically. The concept is based on echo-enabled harmonic generation (EEHG), wherein two modulator-chicane sections impose high harmonic structure with much greater efficacy as compared to conventional high harmonic FELs that use only one modulator-chicane section. The idea proposed here is to replace the external laser power sources in the EEHG modulators with FEL oscillators, and to combine the bunching of the beam with the production of radiation. Tunability is accomplished by adjusting the magnetic chicanes while the two oscillators remain at a fixed frequency. This scheme eliminates the need to develop coherent sources with the requisite power, pulse length, and stability requirements by exploiting the MHz bunch repetition rates of FEL continuous wave (CW) sources driven by superconducting (SC) linacs. We present time-dependent GINGER simulation results for an EEHG scheme with an oscillator modulator at 43 nm employing 50percent reflective dielectric mirrors and a second modulator employing an external, 215-nm drive laser. Peak output of order 300 MW is obtained at 2.7 nm, corresponding to the 80th harmonic of 215 nm. An alternative single-cavity echo-oscillator scheme based on a 13.4 nm oscillator is investigated with time-independent simulations that a 180-MW peak power at final wavelength of 1.12 nm. Three alternate configurations that use separate bunches to produce the radiation for EEHG microbunching are also presented. Our results show that oscillator-based soft x-ray FELs driven by CWSC linacs are extremely attractive because of their potential to produce tunable radiation at high average power together with excellent longitudinal coherence and narrow spectral bandwidth.

  11. Narrow-Band WGM Optical Filters With Tunable FSRs

    Science.gov (United States)

    Mohageg, Makan; Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute; Iltchenko, Vladimir; Strekalov, Dmitry

    2007-01-01

    Optical resonators of the whispering-gallery-mode (WGM) type featuring DC-tunable free spectral ranges (FSRs) have been demonstrated. By making the FSR tunable, one makes it possible to adjust, during operation, the frequency of a microwave signal generated by an optoelectronic oscillator in which an WGM optical resonator is utilized as a narrow-band filter.

  12. A low-loss, continuously tunable microwave notch filter

    DEFF Research Database (Denmark)

    Acar, Öncel; Johansen, Tom Keinicke; Zhurbenko, Vitaliy

    2016-01-01

    The development in high-end microwave transceiver systems toward the software defined radio has brought about the need for tunable frontend filters. Although the problem is being tackled by the microwave community, there still appears to be an unmet demand for practical tunable filter technologies...

  13. Development of Research Infrastructure in Nevada for the Exploitation of Hyperspectral Image Data to Address Proliferation and Detection of Chemical and Biological Materials.

    Energy Technology Data Exchange (ETDEWEB)

    James V. Taranik

    2007-12-31

    This research was to exploit hyperspectral reflectance imaging technology for the detection and mapping variability (clutter) of the natural background against which gases in the atmosphere are imaged. The natural background consists of landscape surface cover composed of consolidated rocks, unconsolidated rock weathering products, soils, coatings on rock materials, vegetation, water, materials constructed by humans, and mixtures of the above. Human made gases in the atmosphere may indicate industrial processes important to detecting non-nuclear chemical and biological proliferation. Our research was to exploit the Visible and Near-Infrared (NIR) and the Short-wave Infrared (SWIR) portions of the electromagnetic spectrum to determine the properties of solid materials on the earth’s surface that could influence the detection of gases in the Long-Wave Infrared (LWIR). We used some new experimental hyperspectral imaging technologies to collect data over the Non-Proliferation Test and Evaluation Center (NPTEC) located on the Nevada Test Site (NTS). The SpecTIR HyperSpecTIR (HST) and Specim Dual hyperspectral sensors were used to understand the variability in the imaged background (clutter), that detected, measured, identified and mapped with operational commercial hyperspectral techniques. The HST sensors were determined to be more experimental than operational because of problems with radiometric and atmospheric data correction. However the SpecTIR Dual system, developed by Specim in Finland, eventually was found to provide cost-effective hyperspectral image data collection and it was possible to correct the Dual system’s data for specific areas. Batch processing of long flightlines was still complex, and if comparison to laboratory spectra was desired, the Dual system data still had to be processed using the empirical line method. This research determined that 5-meter spatial resolution was adequate for mapping natural background variations. Furthermore, this

  14. Fibonacci optical lattices for tunable quantum quasicrystals

    Science.gov (United States)

    Singh, K.; Saha, K.; Parameswaran, S. A.; Weld, D. M.

    2015-12-01

    We describe a quasiperiodic optical lattice, created by a physical realization of the abstract cut-and-project construction underlying all quasicrystals. The resulting potential is a generalization of the Fibonacci tiling. Calculation of the energies and wave functions of ultracold atoms loaded into such a lattice demonstrate a multifractal energy spectrum, a singular continuous momentum-space structure, and the existence of controllable edge states. These results open the door to cold atom quantum simulation experiments in tunable or dynamic quasicrystalline potentials, including topological pumping of edge states and phasonic spectroscopy.

  15. Magnetocapacitance of an electrically tunable silicene device

    KAUST Repository

    Tahir, M.

    2012-09-26

    Despite their structural similarity, the electronic properties of silicene are fundamentally different from those of well-known graphene due to the strong intrinsic spin orbit interaction and buckled structure of silicene. We address the magnetocapacitance of spin and valley polarized silicene in an external perpendicular magnetic field to clarify the interplay of the spin orbit interaction and the perpendicular electric field. We find that the band gap is electrically tunable and show that the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high magnetic field.

  16. Electrostatically tunable optomechanical "zipper" cavity laser

    CERN Document Server

    Perahia, Raviv; Meenehan, Sean; Alegre, Thiago P Mayer; Painter, Oskar

    2010-01-01

    A tunable nanoscale "zipper" laser cavity, formed from two doubly clamped photonic crystal nanobeams, is demonstrated. Pulsed, room temperature, optically pumped lasing action at a wavelength of 1.3 micron is observed for cavities formed in a thin membrane containing InAsP/GaInAsP quantum-wells. Metal electrodes are deposited on the ends of the nanobeams to allow for micro-electro-mechanical actuation. Electrostatic tuning and modulation of the laser wavelength is demonstrated at a rate of 0.25nm/V^2 and a frequency as high as 6.7MHz, respectively.

  17. Electronically tunable phase locked loop oscillator

    Science.gov (United States)

    Balasis, M.; Davis, M. R.; Jackson, C. R.

    1982-02-01

    This report describes the design and development of a low noise, high power, variable oscillator incorporating a high 'Q' electronically tunable resonator as the frequency determining element. The VCO provides improved EMC performance in phase locked synthesizers which are a part of communications equipments. The oscillator combines a low noise VMOS transistor with the selectivity and out-of-band attenuation of a coaxial resonator to provide superior EMC performance. Several oscillator designs were examined and the basis for the final configuration is presented. Oscillator noise is discussed and models for analysis are explained. A brass board model was constructed and tested and the technical results are presented.

  18. Tunability of optofluidic distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Kristensen, Anders

    2007-01-01

    We investigate the tunability of optofluidic distributed feedback (DFB) dye lasers. The lasers rely on light-confinement in a nano-structured polymer film where an array of nanofluidic channels constitutes a third order Bragg grating DFB laser resonator with a central phase-shift. The lasers...... are operated by filling the DFB laser resonator with a dye solution by capillary action and optical pumping with a frequency doubled Nd: YAG laser. The low reflection order of the DFB laser resonator yields low out-of-plane scattering losses as well as a large free spectral range (FSR), and low threshold...

  19. Tunable Antenna Coupled Intersubband Terahertz Detector

    CERN Document Server

    Gautam, Nutan; Chahat, Nacer; Karasik, Boris; Focardi, Paolo; Gulkis, Samuel; Pfeiffer, Loren; Sherwin, Mark

    2014-01-01

    We report on the development of a tunable antenna coupled intersubband terahertz (TACIT) detector based on GaAs/AlGaAs two dimensional electron gas. A successful device design and micro-fabrication process have been developed which maintain the high mobility (1.1x106 cm2/V-s at 10K) of a 2DEG channel in the presence of a highly conducting backgate. Gate voltage-controlled device resistance and direct THz sensing has been observed. The goal is to operate as a nearly quantum noise limited heterodyne sensor suitable for passively-cooled space platforms.

  20. Tunable nonlinear absorption of hydrogenated nanocrystalline silicon.

    Science.gov (United States)

    Ma, Y J; Oh, J I; Zheng, D Q; Su, W A; Shen, W Z

    2011-09-01

    Nonlinear absorption (NLA) of hydrogenated nanocrystalline silicon (nc-Si:H) has been investigated through the open aperture Z-scan method for the photon energy of the incident irradiance slightly less than the bandgap of the sample. NLA responses have been observed to be highly sensitive to the wavelength and intensity of the incident irradiance as well as to the bandgap of the sample, indicating greatly tunable NLA of nc-Si:H. The band tail of nc-Si:H appears to play a crucial role in such NLA responses.

  1. Three Cavity Tunable MEMS Fabry Perot Interferometer

    Directory of Open Access Journals (Sweden)

    Narayanswamy Sivakumar

    2007-12-01

    Full Text Available In this paper a four-mirror tunable micro electro-mechanical systems (MEMSFabry Perot Interferometer (FPI concept is proposed with the mathematical model. Thespectral range of the proposed FPI lies in the infrared spectrum ranging from 2400 to 4018(nm. FPI can be finely tuned by deflecting the two middle mirrors (or by changing the threecavity lengths. Two different cases were separately considered for the tuning. In case one,tuning was achieved by deflecting mirror 2 only and in case two, both mirrors 2 and 3 weredeflected for the tuning of the FPI.

  2. Magnetic nanoparticles for tunable microwave metamaterials

    KAUST Repository

    Noginova, Natalia

    2012-09-24

    Commonly, metamaterials are electrically engineered systems with optimized spatial arrangement of subwavelength sized metal and dielectric components. We explore alternative methods based on use of magnetic inclusions, such as magnetic nanoparticles, which can allow permeability of a composite to be tuned from negative to positive at the range of magnetic resonance. To better understand effects of particle size and magnetization dynamics, we performed electron magnetic resonance study on several varieties of magnetic nanoparticles and determined potential of nanoparticle use as building blocks for tunable microwave metamaterials. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  3. 600-GHz Electronically Tunable Vector Measurement System

    Science.gov (United States)

    Dengler, Robert; Maiwald, Frank; Siegel, Peter

    2007-01-01

    A compact, high-dynamic-range, electronically tunable vector measurement system that operates in the frequency range from approximately 560 to approximately 635 GHz has been developed as a prototype of vector measurement systems that would be suitable for use in nearly-real-time active submillimeter-wave imaging. As used here, 'vector measurement system" signifies an instrumentation system that applies a radio-frequency (RF) excitation to an object of interest and measures the resulting amplitude and phase response, relative to either the applied excitatory signal or another reference signal related in a known way to applied excitatory signal.

  4. Tunable transport mean free path of light in xerogel matrixes embedded with polystyrene spheres

    CERN Document Server

    Bret, B P J; Amaro, M; Nunes-Pereira, E J; Belsley, M

    2008-01-01

    Xerogel matrices, made by sol-gel techniques, are embedded with polystyrene spheres to promote multiple scattering of light. Varying the concentration of the spheres inside the matrix allows one to adjust the transport mean free path of light inside the material. Coherent backscattering measurements show that a range of transport mean free paths from 90 to 600 nm is easily achieved. The determination of the matrix refractive index permits a direct comparison to multiple scattering and Mie theory. Such tunable diffusive sol-gel samples can be further optimized as random laser materials.

  5. The application of SRF vs. RDF classification and specifications to the material flows of two mechanical-biological treatment plants of Rome: Comparison and implications.

    Science.gov (United States)

    Di Lonardo, Maria Chiara; Franzese, Maurizio; Costa, Giulia; Gavasci, Renato; Lombardi, Francesco

    2016-01-01

    This work assessed the quality in terms of solid recovered fuel (SRF) definitions of the dry light flow (until now indicated as refuse derived fuel, RDF), heavy rejects and stabilisation rejects, produced by two mechanical biological treatment plants of Rome (Italy). SRF classification and specifications were evaluated first on the basis of RDF historical characterisation methods and data and then applying the sampling and analytical methods laid down by the recently issued SRF standards. The results showed that the dry light flow presented a worst SRF class in terms of net calorific value applying the new methods compared to that obtained from RDF historical data (4 instead of 3). This lead to incompliance with end of waste criteria established by Italian legislation for SRF use as co-fuel in cement kilns and power plants. Furthermore, the metal contents of the dry light flow obtained applying SRF current methods proved to be considerably higher (although still meeting SRF specifications) compared to those resulting from historical data retrieved with RDF standard methods. These differences were not related to a decrease in the quality of the dry light flow produced in the mechanical-biological treatment plants but rather to the different sampling procedures set by the former RDF and current SRF standards. In particular, the shredding of the sample before quartering established by the latter methods ensures that also the finest waste fractions, characterised by higher moisture and metal contents, are included in the sample to be analysed, therefore affecting the composition and net calorific value of the waste. As for the reject flows, on the basis of their SRF classification and specification parameters, it was found that combined with the dry light flow they may present similar if not the same class codes as the latter alone, thus indicating that these material flows could be also treated in combustion plants instead of landfilled. In conclusion, the

  6. Tunable Transmission-Line Metamaterials Mimicking Electromagnetically Induced Transparency

    Science.gov (United States)

    Feng, T. H.; Han, H. P.

    2016-11-01

    Tunable transmission-line (TL) metamaterials mimicking electromagnetically induced transparency (EIT) have been studied. Firstly, two types of tunable TL EIT-like metamaterial, based on the double split-ring resonator (DSRR) and single split-ring resonator (SSRR), were fabricated and their transmission properties carefully compared. The results showed that the transmittance maximum was almost invariable with shift of the transparency window for the tunable DSRR-based TL EIT-like metamaterial, but for the tunable SSRR-based TL EIT-like metamaterial, the transmittance maximum gradually diminished with shift of the transparency window toward the center of the absorption band. Moreover, the reason for these different transmission properties was explored, revealing that the reduction of the transmittance maximum of the transparency window for the tunable SSRR-based TL EIT-like metamaterial is mainly due to energy loss caused by the resistance of the loaded varactor diodes.

  7. Tunable Handset Antenna: Enhancing Efficiency on TV White Spaces

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Foroozanfard, Ehsan; Morris, Art

    2017-01-01

    With the future LTE auction for TV white spaces at 600 MHz, there is a strong need for efficient handset antennas operating at very low frequencies. This paper shows a tunable antenna covering the LTE bands from 600 MHz to 2.6 GHz. The antenna uses state-of-the-art MEMS tunable capacitors in orde...... to reconfigure its operating frequency. In this work, the design mitigates the tuning loss with a tunable extended ground plane. The resulting dual-resonant antenna exhibits a peak total efficiency of -3.9 dB at 600 MHz.......With the future LTE auction for TV white spaces at 600 MHz, there is a strong need for efficient handset antennas operating at very low frequencies. This paper shows a tunable antenna covering the LTE bands from 600 MHz to 2.6 GHz. The antenna uses state-of-the-art MEMS tunable capacitors in order...

  8. Bioresponsive materials

    Science.gov (United States)

    Lu, Yue; Aimetti, Alex A.; Langer, Robert; Gu, Zhen

    2016-10-01

    'Smart' bioresponsive materials that are sensitive to biological signals or to pathological abnormalities, and interact with or are actuated by them, are appealing therapeutic platforms for the development of next-generation precision medications. Armed with a better understanding of various biologically responsive mechanisms, researchers have made innovations in the areas of materials chemistry, biomolecular engineering, pharmaceutical science, and micro- and nanofabrication to develop bioresponsive materials for a range of applications, including controlled drug delivery, diagnostics, tissue engineering and biomedical devices. This Review highlights recent advances in the design of smart materials capable of responding to the physiological environment, to biomarkers and to biological particulates. Key design principles, challenges and future directions, including clinical translation, of bioresponsive materials are also discussed.

  9. Electrically tunable pore morphology in nanoporous gold thin films

    Institute of Scientific and Technical Information of China (English)

    Tatiana S. Dorofeeva; Erkin Seker

    2015-01-01

    Nanoporous gold (np-Au) is an emerging nanostructured material that exhibits many desirable properties, including high electrical and thermal conductivity, high surface area-to-volume ratio, tunable pore morphology well-established surface-binding chemistry, and compatibility with microfabrication. These features make np-Au a popular material for use in fuel cells, optical and electrical biosensors, drug delivery vehicles, neural electrode coatings, and as a model system for nanoscale mechanics. In each of its many applications, np-Au morphology plays an essential role in the overall device operation. Therefore, precise morphological control is necessary to attain optimal device performance. Traditionally thermal treatment by furnaces and hot plates is used to obtain np-Au with self-similar but coarser morphologies. However, this approach lacks the ability to create different morphologies on a single substrate and requires high temperatures (〉 250 ℃) incompatible with most plastic substrates. Herein, we report electro-annealing as a novel method that permits control of the extent and location of pore coarsening on a single substrate in one fast treatment step. The electro-annealing entails much lower temperatures (〈 150 ℃) than traditional thermal treatment, putatively due to electrically assisted phenomena contributing to the thermally activated surface diffusion of gold atoms, responsible for coarsening. Overall, this approach is easily scaled to display multiple pore morphologies on a single chip, therefore enabling high-throughput screening of optimal nanostructures for specific applications.

  10. Tunable thermoelectric transport in nanomeshes via elastic strain engineering

    Energy Technology Data Exchange (ETDEWEB)

    Piccione, Brian; Gianola, Daniel S., E-mail: gianola@seas.upenn.edu [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2015-03-16

    Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermal management.

  11. Biologically Inspired Self-assembling Synthesis of Bone-like Nano-hydroxyapatite/PLGA- (PEG-ASP)n Composite: A New Biomimetic Bone Tissue Engineering Scaffold Material

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A new biomimetic bone tissue engineering scaffold material, nano-HA/ PLGA-( PEG- ASP )n composite, was synthesized by a biologically inspired self assembling approach. A novel biodegradable PLGA( PEG-ASP ) n copolymer with pendant amine functional groups and enhanced hydrophilicity was synthesized by bulk ring-opening copolymerization by DL-lactide( DLLA ) and glycolide( GA ) with Aspartic acid ( ASP )-Polyethylene glycol( PEG ) alt-prepolymer. A Three-dimensional, porous scaffold of the PLGA-( PEG-ASP )n copolymer was fabricated by a solvent casting, particulate leaching process. The scaffold was then incubated in modified simulated body fluid ( mSBF ) . Growth of HA nanocrystals on the inner pore surfaces of the porous scaffold is confirmed by calcium ion binding analyses, SEM, mass increase measurements and quantification of phosphate content within scaffolds . SEM analysis demonstrated the nucleation and growth of a continuous bonelike, low crystalline carbonated HA nanocrystals on the inner pore surfawes of the PLGA-( PEG-ASP)n scaffolds. The amount of calcium binding, total mass and the mass of pbosphate on experimental PLGA-( PEG- ASP )n scaffolds at different incubation times in mSBF was significantly greater than that of control PLGA scaffolds . This nano-HA/ PLGA- ( PEG-ASP )n composite shows some features of natural bone both in main composition and hierarchical microstructure. The ASPPEG alt-prepolymer modified PLGA copolymer provide a controllable high surface density and distribution of anionic functional groups which would enhauce nucleation and growth of bonelike mineral following exposure to mSBF. This biomimetic treatment provides a simple method for surface funetionalization and subsequent mineral nucleation and self-assembling on biodegradable polymer scaffolds for tissue engineering.

  12. Assessment of the biological effects of welding fumes emitted from metal inert gas welding processes of aluminium and zinc-plated materials in humans.

    Science.gov (United States)

    Hartmann, L; Bauer, M; Bertram, J; Gube, M; Lenz, K; Reisgen, U; Schettgen, T; Kraus, T; Brand, P

    2014-03-01

    The aim of this study was to investigate biological effects and potential health risks due to two different metal-inert-gas (MIG) welding fumes (MIG welding of aluminium and MIG soldering of zinc coated steel) in healthy humans. In a threefold cross-over design study 12 male subjects were exposed to three different exposure scenarios. Exposures were performed under controlled conditions in the Aachener Workplace Simulation Laboratory (AWSL). On three different days the subjects were either exposed to filtered ambient air, to welding fumes from MIG welding of aluminium, or to fumes from MIG soldering of zinc coated materials. Exposure was performed for 6 h and the average fume concentration was 2.5 mg m(-3). Before, directly after, 1 day after, and 7 days after exposure spirometric and impulse oscillometric measurements were performed, exhaled breath condensate (EBC) was collected and blood samples were taken and analyzed for inflammatory markers. During MIG welding of aluminium high ozone concentrations (up to 250 μg m(-3)) were observed, whereas ozone was negligible for MIG soldering. For MIG soldering, concentrations of high-sensitivity CRP (hsCRP) and factor VIII were significantly increased but remained mostly within the normal range. The concentration of neutrophils increased in tendency. For MIG welding of aluminium, the lung function showed significant decreases in Peak Expiratory Flow (PEF) and Mean Expiratory Flow at 75% vital capacity (MEF 75) 7 days after exposure. The concentration of ristocetin cofactor was increased. The observed increase of hsCRP during MIG-soldering can be understood as an indicator for asymptomatic systemic inflammation probably due to zinc (zinc concentration 1.5 mg m(-3)). The change in lung function observed after MIG welding of aluminium may be attributed to ozone inhalation, although the late response (7 days after exposure) is surprising.

  13. Tunable Mechanical Filter for Longitudinal Vibrations

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2007-01-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of vibration isolator called tunable mechanical filter which consists of four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a filter, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the “Pass Bands” and wave propagation is efficiently attenuated within other frequency bands called the “Stop Bands”. The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. The concept of this mechanical filter as presented can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  14. Elastic metamaterial beam with remotely tunable stiffness

    Science.gov (United States)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ˜30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  15. Highly Tunable Electrothermally and Electrostatically Actuated Resonators

    KAUST Repository

    Hajjaj, Amal Z.

    2016-03-30

    This paper demonstrates experimentally, theoretically, and numerically for the first time, a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator actuated electrothermally and electrostatically. Using both actuation methods, we demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally by passing a dc current through it, and electrostatically by applying a dc polarization voltage between the microbeam and the stationary electrode. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Adding a dc bias changes the qualitative nature of the tunability both before and after buckling, which adds another independent way of tuning. This reduces the dip before buckling, and can eliminate it if desired, and further increases the fundamental frequency after buckling. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared with the experimental data and simulation results of a multi-physics finite-element model. A good agreement is found among all the results. [2015-0341

  16. Elastic metamaterial beam with remotely tunable stiffness

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Wei [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Zhengyue [School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Xiaole [School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lai, Yun [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Yellen, Benjamin B., E-mail: yellen@duke.edu [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Mechanical Engineering and Materials Science, Duke University, P.O. Box 90300, Hudson Hall, Durham, North Carolina 27708 (United States)

    2016-02-07

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ∼30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  17. An Investigation of Mechanically Tunable and Nanostructured Polymer Scaffolds for Directing Human Mesenchymal Stem Cell Development

    Science.gov (United States)

    Jaafar, Israd Hakim

    This work investigated the use of biomedically relevant, polymer substrates for in vitro human mesenchymal stem cell (hMSC)-substrate surface interaction. Two materials were identified: (i) Poly(glycerol-sebacate) (PGS), a novel biocompatible and biodegradable thermosetting rubber-like elastomer, and (ii) injection molded polystyrene (PS). PGS was selected because it has tunable mechanical properties within the range of biological tissue, and thus provides a useful model to determine the types of substrate mechanical cues that would elicit specific hMSC lineage specification and possible differentiation outcomes. PS is a relevant material for in vitro cell-substrate surface interaction analysis since it is typically the base material of cell culture dishes. Both these materials have also shown micro to nanoscale molding capabilities. Hence these materials would also serve as a model in determining topographical properties (and related mechanical properties) at the dimension-scale of the extracellular environment that modulates hMSC state and fate. The work characterized, designed, and manufactured substrates made of these materials, for in vitro hMSC culture. Micro/nanoscale PGS and PS surface features were manufactured using silicon (Si) based tooling technology. The response of hMSCs to PGS substrates of various Young.s moduli was examined. hMSC response to a nanoscale array of PS pegs was also investigated. PGS was observed to be a semi-crystalline thermosetting elastomer that is fully amorphous above 35°C. The material acquired increasing stiffness and density of photoresist-coated with increasing levels of curing temperature and duration of cure. hMSCs were observed to respond differently on PGS with elastic modulii of 0.11, 1.11, and 2.30 MPa. The cells spread and proliferate more, and develop a stretched cytoskeleton on the stiffer substrates. On the softest substrate (0.11 MPa) the cells developed a branched and filopodia-rich morphology with a diffused

  18. Tunable photoluminescence across the entire visible spectrum from carbon dots excited by white light.

    Science.gov (United States)

    Hu, Shengliang; Trinchi, Adrian; Atkin, Paul; Cole, Ivan

    2015-03-02

    Although reports have shown shifts in carbon dot emission wavelengths resulting from varying the excitation wavelength, this excitation-dependent emission does not constitute true tuning, as the shifted peaks have much weaker intensity than their dominant emission, and this is often undesired in real world applications. We report for the first time the synthesis and photoluminescence properties of carbon dots whose peak fluorescence emission wavelengths are tunable across the entire visible spectrum by simple adjustment of the reagents and synthesis conditions, and these carbon dots are excited by white light. Detailed material characterization has revealed that this tunable emission results from changes in the carbon dots' chemical composition, dictated by dehydrogenation reactions occurring during carbonization. These significantly alter the nucleation and growth process, resulting in dots with either more oxygen-containing or nitrogen-containing groups that ultimately determine their photoluminescence properties, which is in stark contrast to previous observations of carbon dot excitation-dependent fluorescence. This new ability to synthesize broadband excitable carbon dots with tunable peak emissions opens up many new possibilities, particularly in multimodal sensing, in which multiple analytes and processes could be monitored simultaneously by associating a particular carbon dot emission wavelength to a specific chemical process without the need for tuning the excitation source.

  19. Abnormal glow discharge as a variable capacitor for tunable RF systems

    Science.gov (United States)

    Macheret, Sergey; Semnani, Abbas; Peroulis, Dimitrios

    2016-09-01

    For frequency-tunable resonators and filters in high-power applications, conventional semiconductor devices are easily damaged, while mechanically-tunable systems are bulky and slow. In this regard, weakly ionized plasmas can offer an attractive solution. In this work, an LC resonator circuit where a commercial gas discharge tube (GDT) serves as a variable capacitor was studied experimentally and theoretically. The experiments show continuous decrease of the resonant frequency by up to 50 percent with increase in the DC current through the GDT. Analysis of the current-voltage characteristic and the breakdown parameters, combined with lumped-parameter equivalent-circuit RF simulations, allowed us to determine the gas pressure, the electrode coating material and the secondary emission coefficient, and to achieve a very good agreement between the calculated and measured transmittance values. The analysis reveals that reduction in the cathode sheath thickness with increase in the DC current in the abnormal glow discharge regime is the key factor responsible for the experimentally observed tunability.

  20. Design of tunable devices using one-dimensional Fibonacci photonic crystals incorporating graphene at terahertz frequencies

    Science.gov (United States)

    Bian, Li-an; Liu, Peiguo; Li, Gaosheng

    2016-10-01

    For the one-dimensional generalized Fibonacci photonic crystals incorporating graphene, we present many valuable properties and design the tunable devices accordingly with the help of the transfer matrix method in the frequency range of terahertz. For the common structure, all of dielectric layers are cladded by graphene, we design the high-Q tunable filter with double peaks by changing the Fibonacci distribution and chemical potential. In order to reduce the crosstalk of signals through this filter, a heterostructure based on the current structure and the one without graphene is utilized to separate the two peaks. Also, we fabricate the tunable switch by altering the parity of periodic number. Besides, through cladding the graphene on the one of the dielectrics only, we obtain other two kinds of cells. Combining these cells arbitrarily as the supercell to develop the periodic structure, the number of forbidden bands is increased in accordance with certain rules so that this structure with supercell is suitable as the multi-stop filter. If the active medium is introduced, the imaginary part of the complex permittivity of the material would be negative, which means the energy amplification. For our quasi-periodic structures with active medium, the functions of chemical potential, damping constant and reference wavelength are investigated.