WorldWideScience

Sample records for single nanostructure growth

  1. Helical growth of aluminum nitride: new insights into its growth habit from nanostructures to single crystals.

    Science.gov (United States)

    Zhang, Xing-Hong; Shao, Rui-Wen; Jin, Lei; Wang, Jian-Yu; Zheng, Kun; Zhao, Chao-Liang; Han, Jie-Cai; Chen, Bin; Sekiguchi, Takashi; Zhang, Zhi; Zou, Jin; Song, Bo

    2015-05-15

    By understanding the growth mechanism of nanomaterials, the morphological features of nanostructures can be rationally controlled, thereby achieving the desired physical properties for specific applications. Herein, the growth habits of aluminum nitride (AlN) nanostructures and single crystals synthesized by an ultrahigh-temperature, catalyst-free, physical vapor transport process were investigated by transmission electron microscopy. The detailed structural characterizations strongly suggested that the growth of AlN nanostructures including AlN nanowires and nanohelixes follow a sequential and periodic rotation in the growth direction, which is independent of the size and shape of the material. Based on these experimental observations, an helical growth mechanism that may originate from the coeffect of the polar-surface and dislocation-driven growth is proposed, which offers a new insight into the related growth kinetics of low-dimensional AlN structures and will enable the rational design and synthesis of novel AlN nanostructures. Further, with the increase of temperature, the growth process of AlN grains followed the helical growth model.

  2. Epitaxial growth of hybrid nanostructures

    Science.gov (United States)

    Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

    2018-02-01

    Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

  3. Solution-phase epitaxial growth of noble metal nanostructures on dispersible single-layer molybdenum disulfide nanosheets.

    Science.gov (United States)

    Huang, Xiao; Zeng, Zhiyuan; Bao, Shuyu; Wang, Mengfei; Qi, Xiaoying; Fan, Zhanxi; Zhang, Hua

    2013-02-05

    Compared with the conventional deposition techniques used for the epitaxial growth of metallic structures on a bulk substrate, wet-chemical synthesis based on the dispersible template offers several advantages, including relatively low cost, high throughput, and the capability to prepare metal nanostructures with controllable size and morphology. Here we demonstrate that the solution-processable two-dimensional MoS(2) nanosheet can be used to direct the epitaxial growth of Pd, Pt and Ag nanostructures at ambient conditions. These nanostructures show the major (111) and (101) orientations on the MoS(2)(001) surface. Importantly, the Pt-MoS(2) hybrid nanomaterials exhibit much higher electrocatalytic activity towards the hydrogen evolution reaction compared with the commercial Pt catalysts with the same Pt loading. We believe that nanosheet-templated epitaxial growth of nanostructures via wet-chemical reaction is a promising strategy towards the facile and high-yield production of novel functional materials.

  4. A third kind growth model of tetrapod: Rod-based single crystal ZnO tetrapod nanostructure

    International Nuclear Information System (INIS)

    Gong, J.F.; Huang, H.B.; Wang, Z.Q.; Zhao, X.N.; Yang, S.G.; Yu Zhongzhen

    2008-01-01

    In this paper, rod-based ZnO tetrapods were successfully synthesized by burning Zn particles in air covered with two firebricks. The products show hexagonal wurtzite phase. The microstructures of the tetrapod were studied carefully by scanning electron microscope (SEM), transmission electron microscope (TEM), SAED and HRTEM. The results show that tetrapod has single crystalline phase with one broader nanorod growing along [0 0 0 1] direction, three triangular nanosheets, growing out of the three trisection planes along [101-bar0] direction, and three epitaxial nanowires, growing from each tip of the triangular nanosheets. Based on the experimental results, a rod-based growth model was proposed to interpret its growth mechanism. Room temperature photoluminescence spectrum reveals that the ZnO tetrapods have ultra violet (UV) emission band (389 nm) and a green emission band (517 nm)

  5. Facile Growth of Multi-twined Au Nanostructures

    Indian Academy of Sciences (India)

    We describe a facile growth of chain-like Au nanostructures and their spontaneous transformation to multi-twined nanostructure using a mild reducing agent bisphenol A (BPA). The growth Au nanostructures involves the chemical reduction of HAuCl4 by BPA in the presence of cetyltrimethylammonium bromide (CTAB) as ...

  6. Growth of ZnS nanostructures in high vacuum by thermal evaporation.

    Science.gov (United States)

    Yuvaraj, D; Sathyanarayanan, M; Rao, K Narasimha

    2014-06-01

    ZnS nanostructures were grown on Si substrates in high vacuum by modified thermal evaporation technique. Morphology, chemical composition and structural properties of grown ZnS nanostructures were studied using scanning electron microscope (SEM), X-ray diffractometer and transmission electron microscope (TEM). SEM studies showed that morphology of the grown structures varies with incident flux and source temperature. TEM studies showed that grown nanostructures are single crystalline in nature without structural defects such as stacking faults and twins. No catalytic particle was included in this growth process, and hence these micro and nanostructures were assumed to grow by VS mechanism.

  7. Facile Growth of Multi-twined Au Nanostructures

    Indian Academy of Sciences (India)

    Abstract. We describe a facile growth of chain-like Au nanostructures and their spontaneous transforma- tion to multi-twined nanostructure using a mild reducing agent bisphenol A (BPA). The growth Au nanostruc- tures involves the chemical reduction of HAuCl4 by BPA in the presence of cetyltrimethylammonium bromide.

  8. Low-temperature growth of nanostructured diamond films.

    Science.gov (United States)

    Baker, P A; Catledge, S A; Vohra, Y K

    2001-03-01

    Nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 degrees C) for 30 min using a H2/CH4/N2 gas mixture to grow a thin (approximately 600 nm) nanostructured diamond layer and to improve film adhesion. The remainder of the deposition involves growth at low temperature (diamond film growth during low-temperature deposition is confirmed by in situ laser reflectance interferometry, atomic force microscopy, micro-Raman spectroscopy, and surface profilometry. Similar experiments performed without the initial nanostructured diamond layer resulted in poorly adhered films with a more crystalline appearance and a higher surface roughness. This low-temperature deposition of nanostructured diamond films on metals offers advantages in cases where high residual thermal stress leads to delamination at high temperatures.

  9. Anodic growth of titanium dioxide nanostructures

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

  10. Growth of metal and semiconductor nanostructures using localized photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, John A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wang, Zhongchun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Medforth, Craig J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2006-03-08

    Our overall goal has been to understand and develop a light-driven approach to the controlled growth of novel metal and semiconductor nanostructures and nanomaterials. In this photochemical process, bio-inspired porphyrin-based photocatalysts reduce metal salts in aqueous solutions at ambient temperatures when exposed to visible light, providing metal nucleation and growth centers. The photocatalyst molecules are pre-positioned at the nanoscale to control the location of the deposition of metal and therefore the morphology of the nanostructures that are grown. Self-assembly, chemical confinement, and molecular templating are some of the methods we are using for nanoscale positioning of the photocatalyst molecules. When exposed to light, each photocatalyst molecule repeatedly reduces metal ions from solution, leading to deposition near the photocatalyst and ultimately the synthesis of new metallic nanostructures and nanostructured materials. Studies of the photocatalytic growth process and the resulting nanostructures address a number of fundamental biological, chemical, and environmental issues and draw on the combined nanoscience characterization and multi-scale simulation capabilities of the new DOE Center for Integrated Nanotechnologies at Sandia National Laboratories and the University of Georgia. Our main goals are to elucidate the processes involved in the photocatalytic growth of metal nanomaterials and provide the scientific basis for controlled nanosynthesis. The nanomaterials resulting from these studies have applications in nanoelectronics, photonics, sensors, catalysis, and micromechanical systems. Our specific goals for the past three years have been to understand the role of photocatalysis in the synthesis of dendritic metal (Pt, Pd, Au) nanostructures grown from aqueous surfactant solutions under ambient conditions and the synthesis of photocatalytic porphyrin nanostructures (e.g., nanotubes) as templates for fabrication of photo-active metal

  11. Size-Induced Switching of Nanowire Growth Direction: a New Approach Toward Kinked Nanostructures

    KAUST Repository

    Shen, Youde

    2016-04-26

    Exploring self-assembled nanostructures with controllable architectures has been a central theme in nanoscience and nanotechnology because of the tantalizing perspective of directly integrating such bottom-up nanostructures into functional devices. Here, the growth of kinked single-crystal In2O3 nanostructures consisting of a nanocone base and a nanowire tip with an epitaxial and defect-free transition is demonstrated for the first time. By tailoring the growth conditions, a reliable switching of the growth direction from [111] to [110] or [112] is observed when the Au catalyst nanoparticles at the apexes of the nanocones shrink below ≈100 nm. The natural formation of kinked nanoarchitectures at constant growth pressures is related to the size-dependent free energy that changes for different orientations of the nanowires. The results suggest that the mechanism of forming such kinked nanocone-nanowire nanostructures in well-controlled growth environment may be universal for a wide range of functional materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Interface controlled growth of nanostructures in discontinuous Ag ...

    Indian Academy of Sciences (India)

    The growth of discontinuous thin films of Ag and Au by low energy ion beam sputter deposition is reported. The study ... nance of the metal nanostructures can be tuned over a wide range of wavelengths from 400 to 700 nm by controlling the film–substrate ... on lithographic techniques such as electron beam lithogra-.

  13. Low Temperature Growth of Nanostructured Diamond Films on Metals

    Science.gov (United States)

    Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

    2001-01-01

    The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments

  14. Aluminum as catalyst for ZnO nanostructures growth

    Energy Technology Data Exchange (ETDEWEB)

    Zandalazini, C., E-mail: zc@famaf.unc.edu.ar [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Villafuerte, M. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Oliva, M. [Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Grupo de Ciencia de Materiales, Facultad de Matemática, Astronomía, y Física, Universidad Nacional de Córdoba (Argentina); Heluani, S.P. [Laboratorio de Física del Sólido, Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina)

    2015-05-15

    Highlights: • The efficiency of aluminum as catalyst to grow ZnO nanostructures is proved. • Aluminum as a new catalyst is proposed due to its reduced economic cost. • VSS growth mechanism is the main mechanism using Al as catalyst. • Abrupt diameter change of NWs is discussed due to Al-assisted growth. - Abstract: We report the growth of Al-catalyzed ZnO nanowires (NWs) using a thermal evaporation technique. Before the growth, the substrates were covered with a distribution of Al nano-island that act as seeds. We found that the density of NWs increases as the density of seeds is increased, confirming the catalyst properties of Al. The critical parameters of growth are the substrate temperature, oxygen partial pressure and the thickness of the initial Al layer from which the seeds are formed. The results showed that the oxygen pressure has a strong influence on the structural characteristics: the nanowires exhibit a preferential orientation in the (0 0 l)-planes when they are grown at low oxygen flow, and they become polycrystalline when a high concentration of oxygen in the flow is used. We consider that the growth occurs via a vapor-solid-solid (VSS) process as the predominant growth mechanism.

  15. Growth, structure and lattice dynamics of rare earth silicide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Anja

    2015-07-13

    In the present thesis the epitaxial growth, crystal structure, stoichiometry, thermal stability and lattice dynamics of self-organized EuSi{sub 2} and DySi{sub 2} films, nanoislands and nanowires are investigated. The rare earth silicide (RESi) nanostructures have attracted considerable interest due to their high conductivity, very low Schottky barrier heights, remarkable chemical stability, self-organization in high area density and defects-free nano-objects with tunable size and shape, and the direct integration into the Si technology. The extensive research is driven by the continuous downscaling of the CMOS electronics that require new approaches in the devices architecture and circuits interconnects. Although RESi nanostructures attracted a lot of interest already several years ago and a lot of research has been done in this field, the lattice dynamics of these materials are still unknown. Recent developments at third generation synchrotron radiation sources have brought their performance to a stage where phonon spectroscopy of nanostructures and thin layers became feasible using nuclear inelastic X-ray scattering. This novel experimental technique is based on the process of phonon-assisted nuclear resonant absorption/emission of X-rays from the nuclei of Moessbauer-active isotopes. The method provides direct access to the phonon density of states (DOS) of the investigated element. Together with the ab initio calculations it was possible to get a comprehensive understanding of the lattice dynamics. EuSi{sub 2} films and nanoislands and DySi{sub 2} films, nanoislands and nanowires have been grown on the vicinal Si(001) surface by molecular beam epitaxy. While DySi{sub 2} was grown following known growth procedures, the growth conditions for EuSi{sub 2} had to be established first. EuSi{sub 2} was grown at two different growth conditions to study the influence of crystal structure and morphology upon different growth temperatures. The structure has been

  16. Fabrication of single-crystalline plasmonic nanostructures on transparent and flexible amorphous substrates

    Science.gov (United States)

    Mori, Tomohiro; Mori, Takeshi; Tanaka, Yasuhiro; Suzaki, Yoshifumi; Yamaguchi, Kenzo

    2017-02-01

    A new experimental technique is developed for producing a high-performance single-crystalline Ag nanostructure on transparent and flexible amorphous substrates for use in plasmonic sensors and circuit components. This technique is based on the epitaxial growth of Ag on a (001)-oriented single-crystalline NaCl substrate, which is subsequently dissolved in ultrapure water to allow the Ag film to be transferred onto a wide range of different substrates. Focused ion beam milling is then used to create an Ag nanoarray structure consisting of 200 cuboid nanoparticles with a side length of 160 nm and sharp, precise edges. This array exhibits a strong signal and a sharp peak in plasmonic properties and Raman intensity when compared with a polycrystalline Ag nanoarray.

  17. Computer modelling of the plasma chemistry and plasma-based growth mechanisms for nanostructured materials

    International Nuclear Information System (INIS)

    In this review paper, an overview is given of different modelling efforts for plasmas used for the formation and growth of nanostructured materials. This includes both the plasma chemistry, providing information on the precursors for nanostructure formation, as well as the growth processes itself. We limit ourselves to carbon (and silicon) nanostructures. Examples of the plasma modelling comprise nanoparticle formation in silane and hydrocarbon plasmas, as well as the plasma chemistry giving rise to carbon nanostructure formation, such as (ultra)nanocrystalline diamond ((U)NCD) and carbon nanotubes (CNTs). The second part of the paper deals with the simulation of the (plasma-based) growth mechanisms of the same carbon nanostructures, i.e. (U)NCD and CNTs, both by mechanistic modelling and detailed atomistic simulations.

  18. Single-electron transport in graphene-like nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Kuei-Lin, E-mail: klc43@mit.edu [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Xu, Yang, E-mail: yangxu-isee@zju.edu.cn [Institute of Microelectronics and Optoelectronics, College of Information Science and Electronic Engineering, Zhejiang University, 310027 (China)

    2017-01-31

    Two-dimensional (2D) materials for their versatile band structures and strictly 2D nature have attracted considerable attention over the past decade. Graphene is a robust material for spintronics owing to its weak spin–orbit and hyperfine interactions, while monolayer transition metal dichalcogenides (TMDs) possess a Zeeman effect-like band splitting in which the spin and valley degrees of freedom are nondegenerate. The surface states of topological insulators (TIs) exhibit a spin–momentum locking that opens up the possibility of controlling the spin degree of freedom in the absence of an external magnetic field. Nanostructures made of these materials are also viable for use in quantum computing applications involving the superposition and entanglement of individual charge and spin quanta. In this article, we review a selection of transport studies addressing the confinement and manipulation of charges in nanostructures fabricated from various 2D materials. We supply the entry-level knowledge for this field by first introducing the fundamental properties of 2D bulk materials followed by the theoretical background relevant to the physics of nanostructures. Subsequently, a historical review of experimental development in this field is presented, from the early demonstration of graphene nanodevices on SiO{sub 2} substrate to more recent progress in utilizing hexagonal boron nitride to reduce substrate disorder. In the second part of this article, we extend our discussion to TMDs and TI nanostructures. We aim to outline the current challenges and suggest how future work will be geared towards developing spin qubits in 2D materials.

  19. Growth and characterization of two-dimensional nanostructures

    International Nuclear Information System (INIS)

    Herrera Sancho, Oscar Andrey

    2008-01-01

    Two dimensional nanostructures of palladium, nickel, silver and gadolinium were grown by means of physical evaporation in atmospheres of high vacuum and ultra high vacuum. The qualitative characterization, in situ, of the nanostructures was carried out with techniques of surface analysis: Auger electron spectroscopy and X-ray photoelectron spectroscopy (XPS). The model for the quantification of contaminants in the nanostructures, was proposed by Seah and Shirley, and was made using the spectra XPS measured in situ in the atmospheres of vacuum. For the two-dimensional nanostructures of gadolinium of thicknesses 8 Å, 16 Å, 24 Å, 32 Å, 36 Å, 44 Å, 50 Å, 61 Å, 77 Å, 81 Å, 92 Å and 101 Å, were obtained optical spectra of transmission measured in situ. An band of absorption centered at approximately 2,40 eV is obtained by an increase in the dynamic conductivity from the optical constants, i.e. refractive index and extinction coefficient, of the nanostructure of gadolinium. In addition, the optical constants for the gadolinium nanostructures have presented a maximum of 80 Å of thickness and then it was continued a decreasing tendency toward the values that were reported in the literature for bulk of gadolinium. (author) [es

  20. Studies on the controlled growth of InAs nanostructures on scission surfaces

    International Nuclear Information System (INIS)

    Bauer, J.

    2006-01-01

    The aim of this thesis was the controlled alignment of self-assembled InAs nano-structures on a {110}-oriented surface. The surface is prestructured with the atomic precision offered by molecular beam epitaxy, using the cleaved edge overgrowth-technique. On all samples grown within this work, the epitaxial template in the first growth step was deposited on a (001)GaAs substrate, while the InAs-layer forming the nanostructures during the second growth step was grown on cleaved {110}-GaAs surfaces. Atomic Force Microscopy (AFM) investigations demonstrate the formation of quantum dot (QD)-like nanostructures on top of the AlAs-stripes. X-ray diffraction measurements on large arrays of aligned quantum dots demonstrate that the quantum dots are formed of pure InAs. First investigations on the optical properties of these nanostructures were done using microphotoluminescence-spectroscopy with both high spatial and spectral resolution. (orig.)

  1. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection

    Energy Technology Data Exchange (ETDEWEB)

    Phatak, C., E-mail: cd@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Knoop, L. de; Houdellier, F.; Gatel, C. [CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse (France); Université Paul Sabatier, F-31000 Toulouse (France); Hÿtch, M.J.; Masseboeuf, A. [CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse (France)

    2016-05-15

    One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures. - Highlights: • Novel method for tomography of 3D electromagnetic fields from a single image is presented. • The method relies upon using cylindrical symmetry and is applied to 1D nanostructures. • The 3D magnetic field of a Nickel nanowire is reconstructed. • The 3D electric field from a biased carbon cone nanotip is reconstructed. • Our method improves the quantitative measurement of the 3D electromagnetic fields.

  2. Directed electroless growth of metal nanostructures on patterned self-assembled monolayers.

    Science.gov (United States)

    Garno, Jayne C; Zangmeister, Christopher D; Batteas, James D

    2007-07-03

    The directed placement of Cu nanostructures on surfaces has been studied using a combination of scanning probe lithography and electroless metal deposition onto nanopatterned SAMs of 16-mercaptohexadecanoic acid (16-MHA) on Au. In situ studies using nanoscale molecular gradients reveal how controlling the areal density of the 16-MHA molecules dictates the nucleation and growth of the metal nanostructures. The influence of controlling pattern line spacing and tip path on pattern feature fidelity is also discussed.

  3. Evolution between self-assembled single and double ring-like nanostructures

    International Nuclear Information System (INIS)

    Lee, J H; Wang, Zh M; Abuwaar, Z Y; Strom, N W; Salamo, G J

    2006-01-01

    The evolution between lattice-matched GaAs/Al 0.3 Ga 0.7 As single and double ring-like nanostructures is studied, with an emphasis on the construction and destruction of the observed outer ring. Using droplet epitaxy, this was achieved by directly controlling the Ga surface diffusion on GaAs(100). Double ring-like nanostructures were observed at relatively low temperatures under a fixed As 4 flux (beam equivalent pressure (BEP) of 6.4 μTorr) and at a fixed temperature under a high As 4 flux. The construction of the outer ring can be controlled through surface diffusion by varying the substrate temperature or the As 4 flux. Single ring-like nanostructures were realized both at relatively high temperatures under a fixed As 4 flux, and at low temperatures under a relatively low As 4 flux

  4. Nanostructures based on alumina hydroxides inhibit tumor growth

    Science.gov (United States)

    Fomenko, A. N.; Korovin, M. S.

    2017-09-01

    Nanoparticles and nanostructured materials are one of the most promising developments for cancer therapy. Gold nanoparticles, magnetic nanoparticles based on iron and its oxides and other metal oxides have been widely used in diagnosis and treatment of cancer. Much less research attention has been payed to nanoparticles and nanostructures based on aluminum oxides and hydroxides as materials for cancer diagnosis and treatment. However recent investigations have shown promising results regarding these objects. Here, we review the antitumor results obtained with AlOOH nanoparticles.

  5. Effect of droplet morphology on growth dynamics and heat transfer during condensation on superhydrophobic nanostructured surfaces.

    Science.gov (United States)

    Miljkovic, Nenad; Enright, Ryan; Wang, Evelyn N

    2012-02-28

    Condensation on superhydrophobic nanostructured surfaces offers new opportunities for enhanced energy conversion, efficient water harvesting, and high performance thermal management. These surfaces are designed to be Cassie stable and favor the formation of suspended droplets on top of the nanostructures as compared to partially wetting droplets which locally wet the base of the nanostructures. These suspended droplets promise minimal contact line pinning and promote passive droplet shedding at sizes smaller than the characteristic capillary length. However, the gas films underneath such droplets may significantly hinder the overall heat and mass transfer performance. We investigated droplet growth dynamics on superhydrophobic nanostructured surfaces to elucidate the importance of droplet morphology on heat and mass transfer. By taking advantage of well-controlled functionalized silicon nanopillars, we observed the growth and shedding behavior of suspended and partially wetting droplets on the same surface during condensation. Environmental scanning electron microscopy was used to demonstrate that initial droplet growth rates of partially wetting droplets were 6× larger than that of suspended droplets. We subsequently developed a droplet growth model to explain the experimental results and showed that partially wetting droplets had 4-6× higher heat transfer rates than that of suspended droplets. On the basis of these findings, the overall performance enhancement created by surface nanostructuring was examined in comparison to a flat hydrophobic surface. We showed these nanostructured surfaces had 56% heat flux enhancement for partially wetting droplet morphologies and 71% heat flux degradation for suspended morphologies in comparison to flat hydrophobic surfaces. This study provides insights into the previously unidentified role of droplet wetting morphology on growth rate, as well as the need to design Cassie stable nanostructured surfaces with tailored droplet

  6. Thermal Conductivity in Nanostructured Films: From Single Cellulose Nanocrystals to Bulk Films

    Science.gov (United States)

    Jairo A. Diaz; Zhijiang Ye; Xiawa Wu; Arden L. Moore; Robert J. Moon; Ashlie Martini; Dylan J. Boday; Jeffrey P. Youngblood

    2014-01-01

    We achieved a multiscale description of the thermal conductivity of cellulose nanocrystals (CNCs) from single CNCs (~­0.72−5.7 W m−1 K−1) to their organized nanostructured films (~­0.22−0.53 W m−1 K−1) using...

  7. Top-down fabrication of plasmonic nanostructures for deterministic coupling to single quantum emitters

    NARCIS (Netherlands)

    Pfaff, W.; Vos, A.; Hanson, R.

    2013-01-01

    Metal nanostructures can be used to harvest and guide the emission of single photon emitters on-chip via surface plasmon polaritons. In order to develop and characterize photonic devices based on emitter-plasmon hybrid structures, a deterministic and scalable fabrication method for such structures

  8. Vertically integrated (Ga, In)N nanostructures for future single photon emitters operating in the telecommunication wavelength range

    International Nuclear Information System (INIS)

    Winden, A; Mikulics, M; Grützmacher, D; Hardtdegen, H

    2013-01-01

    Important technological steps are discussed and realized for future room-temperature operation of III-nitride single photon emitters. First, the growth technology of positioned single pyramidal InN nanostructures capped by Mg-doped GaN is presented. The optimization of their optical characteristics towards narrowband emission in the telecommunication wavelength range is demonstrated. In addition, a device concept and technology was developed so that the nanostructures became singularly addressable. It was found that the nanopyramids emit in the telecommunication wavelength range if their size is chosen appropriately. A p-GaN contacting layer was successfully produced as a cap to the InN pyramids and the top p-contact was achievable using an intrinsically conductive polymer PEDOT:PSS, allowing a 25% increase in light transmittance compared to standard Ni/Au contact technology. Single nanopyramids were successfully integrated into a high-frequency device layout. These decisive technology steps provide a promising route to electrically driven and room-temperature operating InN based single photon emitters in the telecommunication wavelength range. (paper)

  9. Vertically integrated (Ga, In)N nanostructures for future single photon emitters operating in the telecommunication wavelength range.

    Science.gov (United States)

    Winden, A; Mikulics, M; Grützmacher, D; Hardtdegen, H

    2013-10-11

    Important technological steps are discussed and realized for future room-temperature operation of III-nitride single photon emitters. First, the growth technology of positioned single pyramidal InN nanostructures capped by Mg-doped GaN is presented. The optimization of their optical characteristics towards narrowband emission in the telecommunication wavelength range is demonstrated. In addition, a device concept and technology was developed so that the nanostructures became singularly addressable. It was found that the nanopyramids emit in the telecommunication wavelength range if their size is chosen appropriately. A p-GaN contacting layer was successfully produced as a cap to the InN pyramids and the top p-contact was achievable using an intrinsically conductive polymer PEDOT:PSS, allowing a 25% increase in light transmittance compared to standard Ni/Au contact technology. Single nanopyramids were successfully integrated into a high-frequency device layout. These decisive technology steps provide a promising route to electrically driven and room-temperature operating InN based single photon emitters in the telecommunication wavelength range.

  10. An SU-8-based microprobe with a nanostructured surface enhances neuronal cell attachment and growth

    Science.gov (United States)

    Kim, Eunhee; Kim, Jin-Young; Choi, Hongsoo

    2017-12-01

    Microprobes are used to repair neuronal injury by recording electrical signals from neuronal cells around the surface of the device. Following implantation into the brain, the immune response results in formation of scar tissue around the microprobe. However, neurons must be in close proximity to the microprobe to enable signal recording. A common reason for failure of microprobes is impaired signal recording due to scar tissue, which is not related to the microprobe itself. Therefore, the device-cell interface must be improved to increase the number of neurons in contact with the surface. In this study, we developed nanostructured SU-8 microprobes to support neuronal growth. Nanostructures of 200 nm diameter and depth were applied to the surface of microprobes, and the attachment and neurite outgrowth of PC12 cells on the microprobes were evaluated. Neuronal attachment and neurite outgrowth on the nanostructured microprobes were significantly greater than those on non-nanostructured microprobes. The enhanced neuronal attachment and neurite outgrowth on the nanostructured microprobes occurred in the absence of an adhesive coating, such as poly- l-lysine, and so may be useful for implantable devices for long-term use. Therefore, nanostructured microprobes can be implanted without adhesive coating, which can cause problems in vivo over the long term.

  11. High spatial resolution spectroscopy of single semiconductor nanostructures

    Science.gov (United States)

    Harris, T. D.; Gershoni, D.; Pfeiffer, L.; Nirmal, M.; Trautman, J. K.; Macklin, J. J.

    1996-11-01

    Low-temperature near-field scanning optical microscopy is used for the first time in spectroscopic studies of single, nanometre dimension, cleaved edge overgrown quantum wires. A direct experimental comparison between a two-dimensional system and a single genuinely one-dimensional quantum wire system, inaccessible to conventional far-field optical spectroscopy, is enabled by the enhanced spatial resolution. We show that the photoluminescence of a single quantum wire is easily distinguished from that of the surrounding quantum well. Emission from localized centres is shown to dominate the photoluminescence from both wires and wells at low temperatures. A factor of three oscillator strength enhancement for these wires compared with the wells is concluded from the photoluminescence excitation data. We also report room-temperature spectroscopy and dynamics of single CdSe nanocrystals. Photochemistry, trap dynamics and spectroscopy are easily determined.

  12. Escape from Flatland: strain and quantum size effect driven growth of metallic nanostructures

    NARCIS (Netherlands)

    Bollmann, Tjeerd Rogier Johannes

    2011-01-01

    In this thesis, we show the influence of and subtle balance between QSE and strain stabilizing interactions on the growth, as well as on structural and electronic properties of nanostructures. We present a LEEM and µLEED study in combination with Tensor LEED calculations illustrating the relevance

  13. Growth of Carbon Nanotubes on Clay: Unique Nanostructured Filler for High-Performance Polymer Nanocomposites

    NARCIS (Netherlands)

    Zhang, Wei-De; Phang, In Yee; Liu, Tianxi

    2006-01-01

    High-performance composites are produced using nanostructured clay-carbon nanotube (CNT) hybrids as a reinforcing filler. The intercalation of iron particles between the clay platelets serves as the catalyst for the growth of CNTs, while the platelets are exfoliated by the CNTs, forming the unique

  14. Selective growth of ZnO thin film nanostructures: Structure, morphology and tunable optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Krishnakanth, Katturi Naga; Sunandana, C. S. [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Rajesh, Desapogu, E-mail: rajesh.esapogu@gmail.com, E-mail: mperd@nus.edu.sg [School of Physics, University of Hyderabad, Hyderabad-50046 (India); Dept. of Mechanical Engineering, National University of Singapore (Singapore)

    2016-05-23

    The ZnO nanostructures (spherical, rod shape) have been successfully fabricated via a thermal evaporation followed by dip coating method. The pure, doped ZnO thin films were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy, respectively. A possible growth mechanism of the spherical, rod shape ZnO nanostructures are discussed. XRD patterns revealed that all films consist of pure ZnO phase and were well crystallized with preferential orientation towards (002) direction. Doping by PVA, PVA+Cu has effective role in the enhancement of the crystalline quality and increases in the band gap.

  15. Nanostructured materials detect epidermal growth factor receptor, neuron specific enolase and carcinoembryonic antigen

    Science.gov (United States)

    Stefan-van Staden, Raluca-Ioana; Comnea-Stancu, Ionela Raluca; Surdu-Bob, Carmen Cristina; Badulescu, Marius

    2015-09-01

    New nanostructured materials based on thin films of Cu and Ni deposited on textile material (veil), as well as gold nanostructured microspheres were used for the design of new stochastic sensors. The stochastic sensors were able to detect simultaneously a panel of biomarkers comprising epidermal growth factor receptor, neuron specific enolase, and carcinoembryonic antigen from whole blood samples with high reliabilities - recovery tests higher than 97.00%, with a RSD (%) lower than 0.1%. The stochastic sensors had shown high sensitivities and low determination levels for the detection of the proposed panel of biomarkers making early detection of lung cancer possible by fast screening of whole blood.

  16. Abnormal grain growth in the nanostructured Invar alloy fabricated by electrodeposition

    Science.gov (United States)

    Park, Hyung-Ki; Hwang, Nong-Moon; Park, Yong Bum

    2012-11-01

    Abnormal grain growth in the nanostructured Invar alloy fabricated by electrodeposition was investigated by electron backscattered diffraction. The observation showed that most of grains growing abnormally during annealing at 380°C have Σ3 boundaries. The observation could be best explained by the mechanism of solid-state wetting, where the Σ3 boundary provides the low-energy boundary, which increases the probability of solid-state wetting, leading to exclusive growth.

  17. Growth of emerald single crystals

    International Nuclear Information System (INIS)

    Bukin, G.V.; Godovikov, A.A.; Klyakin, V.A.; Sobolev, V.S.

    1986-01-01

    In addition to its use for jewelry, emerald can also be used in low-noise microwave amplifiers. The authors discuss flux crystallization of emerald and note that when emerald is grown by this method, it is desirable to use solvents which dissolve emerald with minimum deviations from congruence but at the same time with sufficient high efficiency. Emerald synthesis and crystal growth from slowly cooled solutions is discussed as another possibility. The techniques are examined. Vapor synthesis and growht of beryl crystals re reviewed and the authors experimentally study the seeded CVD crystallization of beryl from BeO, Al 2 O 3 and SiO 2 oxides, by using complex compounds as carrier agents. The color of crystals of emerald and other varieties of beryl is detemined by slelective light absorption in teh visible part of the spectrum and depends on the density and structural positions of chromphore ions: chromium, iron, vanadium, nickel, manganese and cobalt

  18. Strain-hardening in nano-structured single phase steels: mechanisms and control.

    Science.gov (United States)

    Bouaziz, O; Barbier, D

    2012-11-01

    The detrimental effect of grain size refinement on the strain hardening is highlighted in single phase steels. A physical based approach for understanding the underlying mechanisms is presented. In order to overcome this limitation a promising metallurgical route exploiting the thermal stability of mechanically induced twins in austenitic steels has been successfully applied to a stainless grade confirming the opportunity to get nano-structured alloys exhibiting high yield stress with high strain-hardening.

  19. Thermally controlled growth of surface nanostructures on ion-modified AIII-BV semiconductor crystals

    Science.gov (United States)

    Trynkiewicz, Elzbieta; Jany, Benedykt R.; Wrana, Dominik; Krok, Franciszek

    2018-01-01

    The primary motivation for our systematic study is to provide a comprehensive overview of the role of sample temperature on the pattern evolution of several AIII-BV semiconductor crystal (001) surfaces (i.e., InSb, InP, InAs, GaSb) in terms of their response to low-energy Ar+ ion irradiation conditions. The surface morphology and the chemical diversity of such ion-modified binary materials has been characterized by means of scanning electron microscopy (SEM). In general, all surface textures following ion irradiation exhibit transitional behavior from small islands, via vertically oriented 3D nanostructures, to smoothened surface when the sample temperature is increased. This result reinforces our conviction that the mass redistribution of adatoms along the surface plays a vital role during the formation and growth process of surface nanostructures. We would like to emphasize that this paper addresses in detail for the first time the topic of the growth kinetics of the nanostructures with regard to thermal surface diffusion, while simultaneously offering some possible approaches to supplementing previous studies and therein gaining a new insight into this complex issue. The experimental results are discussed with reference to models of the pillars growth, abutting on preferential sputtering, the self-sustained etch masking effect and the redeposition process recently proposed to elucidate the observed nanostructuring mechanism.

  20. Controlled growth of copper oxide nanostructures by atmospheric pressure micro-afterglow

    Science.gov (United States)

    Altaweel, A.; Filipič, G.; Gries, T.; Belmonte, T.

    2014-12-01

    A large variety of copper oxide nanostructures encompassing nanodots, nanowires and nanowalls, sometimes organized in ;cabbage-like; architectures, are grown locally by direct oxidation of copper thin films using the micro-afterglow of an Ar-O2 microwave plasma operating at atmospheric pressure. Morphology, structure and composition of the oxidized copper thin films are characterized by X-ray diffraction, secondary ion mass spectrometry and scanning electron microscopy. The concentric areas where each kind of nanostructures is found are defined by both their radial position with respect to the afterglow centre and by experimental conditions. A growth mechanism is proposed, based on stress-induced outward migration of copper ions. The development of stress gradients is caused by the formation of a copper oxide scale layer. If copper oxide nanowires can be grown as in thermal oxidation processes, micro-afterglow conditions offer novel nanostructures and nano-architectures.

  1. ODMR of single point defects in silicon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovsky, Eduard; Gets, Dmitry; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical-Technical Institute, Polytekhnicheskaya st. 26, 194021 St. Petersburg (Russian Federation)

    2012-05-15

    We present the findings of the optically detected magnetic resonance technique (ODMR), which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor {delta}-barriers. This technique allows the ODMR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the transmission spectra within the frameworks of the excitonic normal-mode coupling caused by the microcavities embedded in the Si-QW plane. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    Science.gov (United States)

    Kan, Cai-Xia; Zhu, Jie-Jun; Zhu, Xiao-Guang

    2008-08-01

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

  3. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    International Nuclear Information System (INIS)

    Kan Caixia; Zhu Jiejun; Zhu Xiaoguang

    2008-01-01

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {1 1 1} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {100} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {1 0 0} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes

  4. Silver nanostructures with well-controlled shapes: synthesis, characterization and growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kan Caixia [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Zhu Jiejun [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhu Xiaoguang [Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)], E-mail: cxkan@nuaa.edu.cn

    2008-08-07

    This paper describes a poly(vinylpyrollidone)-directed polyol synthesis method for the fabrication of silver (Ag) nanostructures with well-controlled shapes (such as nanorods and nanocubes) by adjusting the synthesizing parameters. The structure characterizations suggest that the Ag nanorods grow from the five-fold twinned decahedral crystal nuclei. The nature of the {l_brace}1 1 1{r_brace} planes of Ag crystal and the highly selective poly(vinylpyrollidone) adsorption on the {l_brace}100{r_brace} planes of Ag crystal nuclei are favourable for the formation of Ag nanorods and Ag nanowires. The single crystalline Ag nanocubes obtained at optimum conditions are perfect in shape and are enclosed by the {l_brace}1 0 0{r_brace} facets. The optical properties of the Ag nanostructures show an attractive plasma resonance, displaying a considerable dependence on the shape and size. The formation of the Ag nanostructures with well-defined shapes is probably due to the fact that the nanostructures are controlled thermodynamically and kinetically. The ability to generate shape-controlled Ag nanostructures also provides an opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

  5. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    Science.gov (United States)

    Ma, Ming-Guo

    2012-01-01

    Hierarchically nanosized hydroxyapatite (HA) with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours. Objective The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA) with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks. Methods A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did not decrease with the increasing concentration of hierarchically nanostructured HA added. Conclusion A novel, simple and reliable hydrothermal route had been developed for the synthesis of

  6. Growth of CuS Nanostructures by Hydrothermal Route and Its Optical Properties

    Directory of Open Access Journals (Sweden)

    Murugan Saranya

    2014-01-01

    Full Text Available CuS nanostructures have been successfully synthesized by hydrothermal route using copper nitrate and sodium thiosulphate as copper and sulfur precursors. Investigations were done to probe the effect of cationic surfactant, namely, Cetyltrimethylammonium bromide (CTAB on the morphology of the products. A further study has been done to know the effect of reaction time on the morphology of CuS nanostructures. The FE-SEM results showed that the CuS products synthesized in CTAB were hexagonal plates and the samples prepared without CTAB were nanoplate like morphology of sizes about 40–80 nm. Presence of nanoplate-like structure of size about 40–80 nm was observed for the sample without CTAB. The synthesized CuS nanostructures were characterized by X-ray diffraction (XRD, FE-SEM, DRS-UV-Vis spectroscopy, and FT-IR spectroscopy. A possible growth mechanism has been elucidated for the growth of CuS nanostructures.

  7. Quantitative and Isolated Measurement of Far-Field Light Scattering by a Single Nanostructure

    Science.gov (United States)

    Kim, Donghyeong; Jeong, Kwang-Yong; Kim, Jinhyung; Ee, Ho-Seok; Kang, Ju-Hyung; Park, Hong-Gyu; Seo, Min-Kyo

    2017-11-01

    Light scattering by nanostructures has facilitated research on various optical phenomena and applications by interfacing the near fields and free-propagating radiation. However, direct quantitative measurement of far-field scattering by a single nanostructure on the wavelength scale or less is highly challenging. Conventional back-focal-plane imaging covers only a limited solid angle determined by the numerical aperture of the objectives and suffers from optical aberration and distortion. Here, we present a quantitative measurement of the differential far-field scattering cross section of a single nanostructure over the full hemisphere. In goniometer-based far-field scanning with a high signal-to-noise ratio of approximately 27.4 dB, weak scattering signals are efficiently isolated and detected under total-internal-reflection illumination. Systematic measurements reveal that the total and differential scattering cross sections of a Au nanorod are determined by the plasmonic Fabry-Perot resonances and the phase-matching conditions to the free-propagating radiation, respectively. We believe that our angle-resolved far-field measurement scheme provides a way to investigate and evaluate the physical properties and performance of nano-optical materials and phenomena.

  8. Growth of anisotropic gold nanostructures on conducting glass ...

    Indian Academy of Sciences (India)

    In this paper, we describe a method for the growth of gold nanowires and nanoplates starting from a bilayer array of gold seeds, anchored on electrically conducting indium tin oxide (ITO) substrates. This is based on a seed-mediated growth approach, where the nanoparticles attached on the substrate through molecular ...

  9. Self-assembled growth of nanostructural Ge islands on bromine ...

    Indian Academy of Sciences (India)

    strates by thermal evaporation under high vacuum conditions at room temperature. Ge has grown in a layer-plus-island mode although it is different from the Stranski–Krastanov growth mode ob- served in epitaxial growth. Both the islands and the layer are nanocrystalline. This appears to be a consequence of reduction of ...

  10. Self-assembled growth of nanostructural Ge islands on bromine ...

    Indian Academy of Sciences (India)

    We have deposited relatively thick (∼ 60 nm) Ge layers on Br-passivated Si(111) substrates by thermal evaporation under high vacuum conditions at room temperature. Ge has grown in a layer-plus-island mode although it is different from the Stranski–Krastanov growth mode observed in epitaxial growth. Both the islands ...

  11. Nucleation and growth of copper selective-area atomic layer deposition on palladium nanostructures.

    Science.gov (United States)

    Qi, J; Zimmerman, D T; Weisel, G J; Willis, B G

    2017-10-21

    The nucleation and growth of copper atomic layer deposition (ALD) on palladium have been investigated for applications in nanoscale devices. Palladium nanostructures were fabricated by electron beam lithography and range in size from 250 nm to 5 μm, prepared on oxidized silicon wafers. Copper ALD using Cu(thd) 2 (s) and H 2 (g) as reactants was carried out to selectively deposit copper on palladium seeded regions to the exclusion of surrounding oxide surfaces. Nuclei sizes and densities have been quantified by scanning electron microscopy for different growth conditions. It is found that growth occurs via island growth at temperatures of 150-190 °C and alloy growth at temperatures above 210 °C. In the lower temperature window, nucleation density increases with decreasing temperature, reaching a maximum of 4.8 ± 0.2 × 10 9 /cm 2 at 150 °C, but growth is too slow for significant deposition at the lowest temperatures. At higher temperatures, individual nuclei cannot be quantified due to extensive mixing of copper and palladium layers. For the lower temperatures where nuclei can be quantified, rates of nucleation and growth are enhanced at high H 2 partial pressures. At the smallest length scales, conformality of the deposited over-layers is limited by a finite nuclei density and evolving grain structure that cause distortion of the original nanostructure shape during growth.

  12. Growth and BZO-doping of the nanostructured YBCO thin films on buffered metal substrates

    DEFF Research Database (Denmark)

    Huhtinen, H.; Irjala, M.; Paturi, P.

    2010-01-01

    The growth of the nanostructured YBa2Cu3O6+x (YBCO) films is investigated for the first time on biaxially textured NiW substrates used in coated conductor technology. The optimization process of superconducting layers is made in wide magnetic field and temperature range in order to understand...... the vortex pinning structure and mechanism in our films prepared from nanostructured material. Structural analysis shows that growth mechanism in YBCO films grown on NiW is completely different when compared to YBCO on STO. Films on NiW are much rougher, there is huge in-plane variation of YBCO crystals...... and moreover out-of-plane long range lattice ordering is greatly reduced. Magnetic measurements demonstrate that jc in films grown on NiW is higher in high magnetic fields and low temperatures. This effect is connected to the amount of pinning centres observed in films on metal substrates which are effective...

  13. Tunable nanostructured columnar growth of SnO2 for efficient detection of CO gas

    Science.gov (United States)

    Singh, Avneet; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

    2018-02-01

    The present work is focused on the growth and modification of the columnar nanostructures of SnO2 using a glancing angle deposition (GLAD) assisted rf sputtering technique for low temperature detection of carbon monoxide (CO) gas. The GLAD angle and deposition pressure are optimized to tailor the grow of columnar nanostructures of SnO2, which exhibit an enhanced gas sensing response of 1.50 × 102 towards 500 ppm of CO gas at a comparatively lower operating temperature of 110 °C. The enhanced sensing response at low operating temperature is related to the growth of nanoporous columnar structures of SnO2 thin film under the GLAD configuration, which results in an enhanced interaction of target CO gas molecules with the large surface area of sensing SnO2 thin film. The origin of the sensing mechanism supporting the observed response characteristics towards CO gas is identified and discussed in detail.

  14. Growth of α-sexithiophene nanostructures on C60 thin film layers

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Madsen, Morten; Balzer, Frank

    2014-01-01

    Organic molecular beam grown -sexithiophene (-6T) forms nanostructured thin films on buckminsterfullerene (C60) thin film layers. At substrate temperatures of 300K during growth a rough continuous film is observed, which develop to larger elongated islands and dendritic- as well as needle like ...... fluorescence polarimetry measurements the in-plane orientation of the crystalline sites within the needle like structures is determined. The polarimetry investigations strongly indicate that the needle like structures consist of lying molecules....

  15. Theoretical Studies of Gas Phase Elementary and Carbon Nanostructure Growth Reactions

    Science.gov (United States)

    2013-09-19

    photodissociation reactions of ketene, methylamine, formic acid , methyl ethyl ketone, acetone and NO3. For instance, for NO3, a totally unknown...to photodissociation reactions of ketene, methylamine, formic acid , methyl ethyl ketone, acetone and NO3. For instance, for NO3, a totally unknown...THEORETICAL STUDIES OF GAS PHASE ELEMENTARY AND CARBON NANOSTRUCTURE GROWTH REACTIONS KEIJI MOROKUMA EMORY UNIVERSITY 09/19/2013 Final Report

  16. Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires

    KAUST Repository

    McDowell, Matthew T.

    2011-07-19

    Nanostructured Si is a promising anode material for the next generation of Li-ion batteries, but few studies have focused on the electrical properties of the Li-Si alloy phase, which are important for determining power capabilities and ensuring sufficient electrical conduction in the electrode structure. Here, we demonstrate an electrochemical device framework suitable for testing the electrical properties of single Si nanowires (NWs) at different lithiation states and correlating these properties with structural changes via transmission electron microscopy (TEM). We fi nd that single Si NWs usually exhibit Ohmic I - V response in the lithiated state, with conductivities two to three orders of magnitude higher than in the delithiated state. After a number of sequential lithiation/delithiation cycles, the single NWs show similar conductivity after each lithiation step but show large variations in conductivity in the delithiated state. Finally, devices with groups of NWs in physical contact were fabricated, and structural changes in the NWs were observed after lithiation to investigate how the electrical resistance of NW junctions and the NWs themselves affect the lithiation behavior. The results suggest that electrical resistance of NW junctions can limit lithiation. Overall, this study shows the importance of investigating the electronic properties of individual components of a battery electrode (single nanostructures in this case) along with studying the nature of interactions within a collection of these component structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Large scale fabrication of nitrogen vacancy-embedded diamond nanostructures for single-photon source applications

    Science.gov (United States)

    Jiang, Qianqing; Li, Wuxia; Tang, Chengchun; Chang, Yanchun; Hao, Tingting; Pan, Xinyu; Ye, Haitao; Li, Junjie; Gu, Changzhi

    2016-11-01

    Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser, even at room temperature. However, the photon collection efficiency of bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, we fabricated arrays of diamond nanostructures, differing in both diameter and top end shape, with HSQ and Cr as the etching mask materials, aiming toward large scale fabrication of single-photon sources with enhanced collection efficiency made of nitrogen vacancy (NV) embedded diamond. With a mixture of O2 and CHF3 gas plasma, diamond pillars with diameters down to 45 nm were obtained. The top end shape evolution has been represented with a simple model. The tests of size dependent single-photon properties confirmed an improved single-photon collection efficiency enhancement, larger than tenfold, and a mild decrease of decoherence time with decreasing pillar diameter was observed as expected. These results provide useful information for future applications of nanostructured diamond as a single-photon source. Project supported by the National Key Research and Development Plan of China (Grant No. 2016YFA0200402), the National Natural Science Foundation of China (Grants Nos. 11574369, 11574368, 91323304, 11174362, and 51272278), and the FP7 Marie Curie Action (project No. 295208) sponsored by the European Commission.

  18. Growth of anisotropic gold nanostructures on conducting glass ...

    Indian Academy of Sciences (India)

    WINTEC

    Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai 600 036 e-mail: pradeep@iitm.ac.in. Abstract. In this paper, we describe a method for the growth of ... of metal nanoparticles of diverse shape and size has become a major area of research due to their geometry-dependent properties and potential.

  19. The competition between template growth and catalytic growth of one-dimensional ZnS nanostructures: nanobelts or nanowires.

    Science.gov (United States)

    You, Tingting; Wang, Junli; Feng, Hui; Chen, Kangmin; Fan, Weiling; Zhang, Chi; Miao, Runsheng

    2013-06-07

    Template growth and catalytic growth are two typical mechanisms for the solution-chemistry synthesis of one-dimensional (1D) II-VI semiconductor nanomaterials. Here, we systematically demonstrate the competition relationship between them by tuning the synthesis of 1D ZnS nanostructures in different chain-length primary alkyl-amines. The template growth, derived from the coordination effect of amines, produces ZnS nanobelts and will compete with the Ag2S-catalyzed mechanism as AgNO3 is added into these amines. In short-chain n-propylamine and n-butylamine the template growth is much stronger than the catalytic growth, leading to the morphology maintenance of ZnS nanobelts, whereas the latter replaces the former in long-chain n-octylamine and n-dodecylamine due to the decrease of coordination ability of amines, which yields ZnS nanowires instead of nanobelts. A balance of competition is built between these two mechanisms in middle-length n-hexylamine, producing a mixture of ZnS nanobelts and nanowires. The morphology and growth mechanism changes of ZnS nanostructures have been rationally investigated using various characterization techniques. Meanwhile, the optical properties of the products synthesized before and after adding AgNO3 are comparatively studied by UV-vis absorption and photoluminescence (PL) spectra.

  20. Growth and characterization of multiferroic barium titanate-cobalt ferrite thin film nanostructures

    Science.gov (United States)

    Zheng, Haimei

    Multiferroic materials which display simultaneous ferroelectricity and magnetism have been stimulating significant interest both from the basic science and application point of view. It was proposed that composites with one piezoelectric phase and one magnetostrictive phase can be magnetoelectrically coupled via a stress mediation. The coexistence of magnetic and electric subsystems as well as the magnetoelectric effect of the material allows an additional degree of freedom in the design of actuators, transducers, and storage devices. Previous work on such materials has been focused on bulk ceramics. In the present work, we created vertically aligned multiferroic BaTiO 3-CoFe2O4 thin film nanostructures using pulsed laser deposition. Spinel CoFe2O4 and perovskite BaTiO 3 spontaneously separated during the film growth. CoFe2O 4 forms nano-pillar arrays embedded in a BaTiO3 matrix, which show three-dimensional heteroepitaxy. CoFe2O4 pillars have uniform size and spacing. As the growth temperature increases the lateral size of the pillars also increases. The size of the CoFe2O 4 pillars as a function of growth temperature at a constant growth rate follows an Arrhenius behaviour. The formation of the BaTiO3-CoFe 2O4 nanostructures is a process directed by both thermodynamic equilibrium and kinetic diffusion. Lattice mismatch strain, interface energy, elastic moduli and molar ratio of the two phases, etc., are considered to play important roles in the growth dynamics leading to the nanoscale pattern formation of BaTiO3-CoFe2O4 nanostructures. Magnetic measurements exhibit that all the films have a large uniaxial magnetic anisotropy with an easy axis normal to the film plane. It was calculated that stress anisotropy is the main contribution to the anisotropy field. We measured the ferroelectric and piezoelectric properties of the films, which correspond to the present of BaTiO3 phase. The system shows a strong coupling of the two order parameters of polarization and

  1. Growth Mechanisms and Characteristics of ZnO Nanostructures Doped with In and Ga

    Science.gov (United States)

    Yang, Su-Hua; Hong, Sheng-Yu; Tsai, Cheng-Hsun

    2010-06-01

    In this paper we present the crystallization, photoluminescence (PL), and field-emission (FE) properties of ZnO nanostructures doped with In and Ga cationic substituents and grown by the vapor-phase transport process. During the growth, Zn/ZnOx was adsorbed on the surface of Ag nanograins and self-catalyzed to form ZnO nanoparticles. Hexagonal-faced nanobricks and nanorods were grown by increasing the ZnO vapor concentration. However, nanodisks rather than nanobricks were grown when In2O3 was doped. Furthermore, the nanodisks aggregated to form nanoballs when the synthesis was carried out at high In2O3 doping concentrations. In contrast, nanostructures with a sea-urchin-like morphology were grown when Ga2O3 was doped; individual nanorods with a screw-dislocation structure grew from the same root. We present the growth mechanisms for the ZnO, ZnO:In, and ZnO:Ga nanostructures. ZnO:Ga nanorods exhibited better PL intensity and FE properties than ZnO nanorods and ZnO:In nanoballs.

  2. Membrane-Assisted Growth of DNA Origami Nanostructure Arrays

    Science.gov (United States)

    2015-01-01

    Biological membranes fulfill many important tasks within living organisms. In addition to separating cellular volumes, membranes confine the space available to membrane-associated proteins to two dimensions (2D), which greatly increases their probability to interact with each other and assemble into multiprotein complexes. We here employed two DNA origami structures functionalized with cholesterol moieties as membrane anchors—a three-layered rectangular block and a Y-shaped DNA structure—to mimic membrane-assisted assembly into hierarchical superstructures on supported lipid bilayers and small unilamellar vesicles. As designed, the DNA constructs adhered to the lipid bilayers mediated by the cholesterol anchors and diffused freely in 2D with diffusion coefficients depending on their size and number of cholesterol modifications. Different sets of multimerization oligonucleotides added to bilayer-bound origami block structures induced the growth of either linear polymers or two-dimensional lattices on the membrane. Y-shaped DNA origami structures associated into triskelion homotrimers and further assembled into weakly ordered arrays of hexagons and pentagons, which resembled the geometry of clathrin-coated pits. Our results demonstrate the potential to realize artificial self-assembling systems that mimic the hierarchical formation of polyhedral lattices on cytoplasmic membranes. PMID:25734977

  3. Fabrication and in-situ STM investigation of growth dynamics of semiconductor nanostructures grown by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Borisova, Svetlana

    2012-05-23

    Modern development of information technologies requires an introduction of new fundamental concepts, in order to create more efficient devices and to decrease their size. One of the most promising ways is to increase the functionality of silicon by integrating novel materials into Si-based production. This PhD thesis reports on the fabrication and investigation of the growth of semiconductor nanostructures on Si substrates by molecular beam epitaxy (MBE). In-situ scanning tunneling microscopy (STM) is a powerful technique in order to study morphological and electronic properties of the grown structures directly under ultra high vacuum (UHV) conditions. It is shown that the combination of MBE and in-situ STM enables the study of nucleation and growth dynamics at the atomic scale. It provides us with numerous information concerning the nucleation mechanism, the growth mode of the structures, adatom kinetics, influence of the lattice mismatch between the substrate and the grown structure as well as formation and morphology of crystal defects. The first part of the thesis focuses on the experimental realization based upon an existing setup. The construction of an in-situ UHV STM compatible with the MBE cluster and the technical improvement of the STM setup are described. Subsequently, test measurements are performed on the technologically most important surfaces, Ge (100) and Si (111). The second part of the thesis is dedicated to ordered small-period arrays of self-assembled Ge quantum dots (QDs) grown on pre-patterned Si (100) substrates. Small-period Ge QD crystals are highly interesting since band structure calculations indicate coupled electronic states of the QDs in the case of the small lateral period of approximately 30 nm. Small-period hole patterns with a period of 56 nm are fabricated by e-beam lithography on Si substrates. The evolution of the hole morphology during the in-situ pre-growth annealing and the Si buffer layer growth are studied. Deposition of 5

  4. Fabrication and in-situ STM investigation of growth dynamics of semiconductor nanostructures grown by MBE

    International Nuclear Information System (INIS)

    Borisova, Svetlana

    2012-01-01

    Modern development of information technologies requires an introduction of new fundamental concepts, in order to create more efficient devices and to decrease their size. One of the most promising ways is to increase the functionality of silicon by integrating novel materials into Si-based production. This PhD thesis reports on the fabrication and investigation of the growth of semiconductor nanostructures on Si substrates by molecular beam epitaxy (MBE). In-situ scanning tunneling microscopy (STM) is a powerful technique in order to study morphological and electronic properties of the grown structures directly under ultra high vacuum (UHV) conditions. It is shown that the combination of MBE and in-situ STM enables the study of nucleation and growth dynamics at the atomic scale. It provides us with numerous information concerning the nucleation mechanism, the growth mode of the structures, adatom kinetics, influence of the lattice mismatch between the substrate and the grown structure as well as formation and morphology of crystal defects. The first part of the thesis focuses on the experimental realization based upon an existing setup. The construction of an in-situ UHV STM compatible with the MBE cluster and the technical improvement of the STM setup are described. Subsequently, test measurements are performed on the technologically most important surfaces, Ge (100) and Si (111). The second part of the thesis is dedicated to ordered small-period arrays of self-assembled Ge quantum dots (QDs) grown on pre-patterned Si (100) substrates. Small-period Ge QD crystals are highly interesting since band structure calculations indicate coupled electronic states of the QDs in the case of the small lateral period of approximately 30 nm. Small-period hole patterns with a period of 56 nm are fabricated by e-beam lithography on Si substrates. The evolution of the hole morphology during the in-situ pre-growth annealing and the Si buffer layer growth are studied. Deposition of 5

  5. Mechanistic Understanding of Tungsten Oxide In-Plane Nanostructure Growth via Sequential Infiltration Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Jin; Suh, Hyo Seon; Zhou, Chun; Mane, Anil U.; Lee, Byeongdu; Kim, Soojeong; Emery, Jonathan D.; Elam, Jeffrey W.; Nealey, Paul F.; Fenter, Paul; Fister, Timothy T.

    2018-02-21

    Tungsten oxide (WO3-x) nanostructures with hexagonal in-plane arrangements were fabricated by sequential infiltration synthesis (SIS), using the selective interaction of gas phase precursors with functional groups in one domain of a block copolymer (BCP) self-assembled template. Such structures are highly desirable for various practical applications and as model systems for fundamental studies. The nanostructures were characterized by cross-sectional scanning electron microscopy, grazing-incidence small/wide-angle X-ray scattering (GISAXS/GIWAXS), and X-ray absorption near edge structure (XANES) measurements at each stage during the SIS process and subsequent thermal treatments, to provide a comprehensive picture of their evolution in morphology, crystallography and electronic structure. In particular, we discuss the critical role of SIS Al2O3 seeds toward modifying the chemical affinity and free volume in a polymer for subsequent infiltration of gas phase precursors. The insights into SIS growth obtained from this study are valuable to the design and fabrication of a wide range of targeted nanostructures.

  6. Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

    International Nuclear Information System (INIS)

    Liscio, F; Maret, M; Doisneau-Cottignies, B; Makarov, D; Albrecht, M; Roussel, H

    2010-01-01

    A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L1 0 chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1 0 variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L1 0 phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

  7. Mechanical properties of single nanostructures investigated by in-situ AFM and micro-XRD

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, Thomas; Scheler, Thomas; Magalhaes-Paniago, Rogerio; Metzger, Till Hartmut [ESRF, Grenoble (France)

    2010-07-01

    In recent years, nanostructures attracted enormous attention due to size-effects influencing the structural, optical, electrical, and mechanical properties of materials with low dimensions. Concerning the mechanical properties mainly the plastic regime was explored showing a trend that ''smaller is stronger''. In contrast, studies of the elastic behaviour of nanowires revealed contradictory results concerning the influence of size-effects on the elasticity. To investigate single nanoobjects in the elastic regime, we combined an in-situ AFM with XRD in a microfocused beam. The AFM is used to image the sample surface, to select an individual nanostructure, and to apply pressure on a chosen object. Due to the interaction between the AFM-tip and the compressed object the resonance frequency of the AFM force sensor shifts to larger values enabling us to derive the stiffness of the contact area. Simultaneous to the pressure application, XRD images around a pre-defined Bragg peak are recorded. These images allow for the determination of the elastic lattice parameter change in-situ. From the contact stiffness and the lattice parameter change, the Young modulus of an individual nanoobject is derived. Here, we present results both for SiGe islands grown by liquid-phase epitaxy on Si wafers and GaAs nanorods created by selective-area metalorganic vapor phase epitaxy on GaAs substrates.

  8. Single-molecule observations of RNA-RNA kissing interactions in a DNA nanostructure.

    Science.gov (United States)

    Takeuchi, Yosuke; Endo, Masayuki; Suzuki, Yuki; Hidaka, Kumi; Durand, Guillaume; Dausse, Eric; Toulmé, Jean-Jacques; Sugiyama, Hiroshi

    2016-01-01

    RNA molecules uniquely form a complex through specific hairpin loops, called a kissing complex. The kissing complex is widely investigated and used for the construction of RNA nanostructures. Molecular switches have also been created by combining a kissing loop and a ligand-binding aptamer to control the interactions of RNA molecules. In this study, we incorporated two kinds of RNA molecules into a DNA origami structure and used atomic force microscopy to observe their ligand-responsive interactions at the single-molecule level. We used a designed RNA aptamer called GTPswitch, which has a guanosine triphosphate (GTP) responsive domain and can bind to the target RNA hairpin named Aptakiss in the presence of GTP. We observed shape changes of the DNA/RNA strands in the DNA origami, which are induced by the GTPswitch, into two different shapes in the absence and presence of GTP, respectively. We also found that the switching function in the nanospace could be improved by using a cover strand over the kissing loop of the GTPswitch or by deleting one base from this kissing loop. These newly designed ligand-responsive aptamers can be used for the controlled assembly of the various DNA and RNA nanostructures.

  9. Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

    National Research Council Canada - National Science Library

    Lee, Haiwon

    2007-01-01

    This project focused on the behavior of single-wall carbon nanotubes (SWCNTs) in the electrophoresis cells and aligned growth of SWCNTs by thermal chemical vapor deposition on selectively deposited metallic nanoparticle...

  10. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. Z. [Quanzhou Normal University, Key Laboratory of Information Functional Material for Fujian Higher Education, College of Physics & Information Engineering (China); Wang, B. B. [Chongqing University of Technology, College of Chemical Engineering (China); Qu, Y. Z.; Huang, X. [Xiamen University, College of Energy, Xiang’an Campus (China); Ostrikov, K. [Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering (Australia); Levchenko, I.; Xu, S. [Nanyang Technological University, Plasma Sources and Applications Centre, National Institute of Education (Singapore); Cheng, Q. J., E-mail: qijin.cheng@xmu.edu.cn [Xiamen University, College of Energy, Xiang’an Campus (China)

    2017-03-15

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O{sub 2}-Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  11. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    International Nuclear Information System (INIS)

    Chen, W. Z.; Wang, B. B.; Qu, Y. Z.; Huang, X.; Ostrikov, K.; Levchenko, I.; Xu, S.; Cheng, Q. J.

    2017-01-01

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O 2 -Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  12. The growth of sapphire single crystals

    Directory of Open Access Journals (Sweden)

    STEVAN DJURIC

    2001-06-01

    Full Text Available Sapphire (Al2O3 single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grashof numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation wc = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523 K was found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  13. Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers

    Science.gov (United States)

    Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing

    2017-08-01

    Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

  14. Metal–Organic Frameworks as Platforms for the Controlled Nanostructuring of Single-Molecule Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Aulakh, Darpandeep; Pyser, Joshua B.; Zhang, Xuan; Yakovenko, Andrey A.; Dunbar, Kim R.; Wriedt, Mario

    2015-07-29

    The prototypical SMM molecule [Mn12O12(O2CCH3)16(OH2)4] was incorporated under mild conditions into a highly porous metal-organic framework (MOF) matrix as a proof of principle for controlled nanostructuring of SMMs. Four independent experiments revealed that the SMM clusters were successfully loaded in the MOF pores, namely synchrotron-based powder diffraction, physisorption analysis, and in-depth magnetic and thermal analyses. The results provide incontrovertible evidence that the magnetic composite, SMM@MOF, combines key SMM properties with the functional properties of MOFs. Most importantly, the incorporated SMMs exhibit a significant enhanced thermal stability with SMM loading advantageously occurring at the periphery of the bulk MOF crystals with only a single SMM molecule isolated in the transverse direction of the pores.

  15. Biomimetic plasmonic color generated by the single-layer coaxial honeycomb nanostructure arrays

    Science.gov (United States)

    Zhao, Jiancun; Gao, Bo; Li, Haoyong; Yu, Xiaochang; Yang, Xiaoming; Yu, Yiting

    2017-07-01

    We proposed a periodic coaxial honeycomb nanostructure array patterned in a silver film to realize the plasmonic structural color, which was inspired from natural honeybee hives. The spectral characteristics of the structure with variant geometrical parameters are investigated by employing a finite-difference time-domain method, and the corresponding colors are thus derived by calculating XYZ tristimulus values corresponding with the transmission spectra. The study demonstrates that the suggested structure with only a single layer has high transmission, narrow full-width at half-maximum, and wide color tunability by changing geometrical parameters. Therefore, the plasmonic colors realized possess a high color brightness, saturation, as well as a wide color gamut. In addition, the strong polarization independence makes it more attractive for practical applications. These results indicate that the recommended color-generating plasmonic structure has various potential applications in highly integrated optoelectronic devices, such as color filters and high-definition displays.

  16. Electrospinning: A versatile technique for making of 1D growth of nanostructured nanofibers and its applications: An experimental approach

    Science.gov (United States)

    Patil, Jyoti V.; Mali, Sawanta S.; Kamble, Archana S.; Hong, Chang K.; Kim, Jin H.; Patil, Pramod S.

    2017-11-01

    One dimensional (1D) metal oxide nanostructures (1D-MONS) play a key role in the development of functional devices including energy conversion, energy storage and environmental devices. They are also used for some important biomedical products like wound dressings, filter media, drug delivery and tissue engineering. The electrospinning (ES) is the versatile technique for making of 1D growth of nanostructured nanofibers, an experimental approach and its applications. The present review is focused on the 1D growth of nanostructured nanofibers in different applications like dye sensitized solar cells, perovskite solar cells, fuel cells, lithium ion batteries, redox flow batteries, supercapacitor, photocatalytic, and gas sensors based on ZnO, TiO2, MnO2, WO3, V2O5, NiO, SnO2, Fe2O3 etc. metal oxides, their composites and carbon. This review article presents an introduction to various types of ES techniques and their technical details. Also, the advantages and disadvantages of each ES technique are summarized. The various technical details such as preparative parameters, post-deposition methods, applied electric field, solution feed rate and a distance between a tip to the collector are the key factors in order to obtain exotic 1D nanostructured materials. Also, the lucid literature survey on the growth of nanostructures of various metal oxides and application in different fields are covered in this review. Further, the future perspectives has also been discussed.

  17. Rapid and Controlled In Situ Growth of Noble Metal Nanostructures within Halloysite Clay Nanotubes.

    Science.gov (United States)

    Rostamzadeh, Taha; Islam Khan, Md Shahidul; Riche', Kyle; Lvov, Yuri M; Stavitskaya, Anna V; Wiley, John B

    2017-11-14

    A rapid (≤2 min) and high-yield low-temperature synthesis has been developed for the in situ growth of gold nanoparticles (NPs) with controlled sizes in the interior of halloysite nanotubes (HNTs). A combination of HAuCl 4 in ethanol/toluene, oleic acid, and oleylamine surfactants and ascorbic acid reducing agent with mild heating (55 °C) readily lead to the growth of targeted nanostructures. The sizes of Au NPs are tuned mainly by adjusting nucleation and growth rates. Further modification of the process, through an increase in ascorbic acid, allows for the formation of nanorods (NRs)/nanowires within the HNTs. This approach is not limited to gold-a modified version of this synthetic strategy can also be applied to the formation of Ag NPs and NRs within the clay nanotubes. The ability to readily grow such core-shell nanosystems is important to their further development as nanoreactors and active catalysts. NPs within the tube interior can further be manipulated by the electron beam. Growth of Au and Ag could be achieved under a converged electron beam suggesting that both Au@HNT and Ag@HNT systems can be used for the fundamental studies of NP growth/attachment.

  18. Effect of nickel seed layer on growth of α-V{sub 2}O{sub 5} nanostructured thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Rabindar Kumar; Kant, Chandra; Kumar, Prabhat; Singh, Megha, E-mail: meghasingh-08@yahoo.com; Reddy, G. B. [Thin film Laboratory, Department of Physics, Indian Institute of Technology Delhi-110016 (India)

    2015-08-28

    In this communication, we reported the role of Ni seed layer on the growth of vanadium pentoxide (α-V{sub 2}O{sub 5}) nanostructured thin films (NSTs) using plasma assisted sublimation process (PASP). Two different substrates, simple glass substrate and the Ni coated glass substrate (Ni thickness ∼ 100 nm) are employing in the present work. The influence of seed layer on structural, morphological, and vibrational properties have been studied systematically. The structural analysis divulged that both films deposited on simple glass as well as on Ni coated glass shown purely orthorhombic phase, no other phases are detected. The morphological studies of V{sub 2}O{sub 5} film deposited on both substrates are carried out by SEM, revealed that features of V{sub 2}O{sub 5} NSTs is completely modified in presence of Ni seed layer and the film possessing the excellent growth of nanorods (NRs) on Ni coated glass rather than simple glass. The HRTEM analysis of NRs is performed at very high magnification, shows very fine fringe pattern, which confirmed the single crystalline nature of nanorods. The vibrational study of NRs is performed using micro-Raman spectroscopy, which strongly support the XRD observations.

  19. Influence of femtosecond laser produced nanostructures on biofilm growth on steel

    Science.gov (United States)

    Epperlein, Nadja; Menzel, Friederike; Schwibbert, Karin; Koter, Robert; Bonse, Jörn; Sameith, Janin; Krüger, Jörg; Toepel, Jörg

    2017-10-01

    Biofilm formation poses high risks in multiple industrial and medical settings. However, the robust nature of biofilms makes them also attractive for industrial applications where cell biocatalysts are increasingly in use. Since tailoring material properties that affect bacterial growth or its inhibition is gaining attention, here we focus on the effects of femtosecond laser produced nanostructures on bacterial adhesion. Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e., a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten identical samples were laser-processed. Subsequently, the samples were subjected to microbial adhesion tests. Bacteria of different shape and adhesion behavior (Escherichia coli and Staphylococcus aureus) were exposed to laser structures and to polished reference surfaces. Our results indicate that E. coli preferentially avoids adhesion to the LIPSS-covered areas, whereas S. aureus favors these areas for colonization.

  20. Characterization of the nanostructure of complexes formed by single- or double-stranded oligonucleotides with a cationic surfactant.

    Science.gov (United States)

    Liu, Xiaoyang; Abbott, Nicholas L

    2010-12-02

    We report the use of dynamic light scattering (DLS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS) to characterize the nanostructure of complexes formed by either single- or double-stranded oligonucleotides with a cationic surfactant (cetyltrimethylammonium bromide, CTAB) in aqueous solution (1 mM Li(2)SO(4)). For single-stranded oligonucleotides 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', both the appearance of two Bragg peaks (at 0.14 and 0.28 Å(-1)) in SAXS spectra with a spacing of 1:2 and form factor fits to SANS spectra are consistent with the presence of multilamellar vesicles (with, on average, 6-9 layers with a periodicity of 45-48 Å). Some samples showed evidence of an additional Bragg peak (at 0.20 Å(-1)) associated with periodic packing (with a periodicity of 31 Å) of the oligonucleotides within the lamellae of the nanostructure. The nucleotide composition of the single-stranded oligonucleotides was also found to impact the number and size of the complexes formed with CTAB. In contrast to 5'-A(20)-3' and 5'-CCCCATTCTAGCAGCCCGGG-3', 5'-T(20)-3' did not change the state of aggregation of CTAB (globular micelles) over a wide range of oligonucleotide:CTAB charge ratios. These results support the proposition that hydrophobic interactions, as well as electrostatics, play a central role in the formation of complexes between cationic amphiphiles and single-stranded oligonucleotides and thus give rise to nanostructures that depend on nucleotide composition. In contrast to the single-stranded oligonucleotides, for double-stranded oligonucleotides mixed with CTAB, three Bragg peaks (0.13, 0.23, and 0.25 Å(-1)) in SAXS spectra with a spacing ratio of 1:√3:√4 and characteristic changes in SANS spectra indicate formation of a hexagonal nanostructure. Also, the composition of the double-stranded oligonucleotides did not measurably impact the nanostructure of complexes formed with CTAB, suggesting that electrostatic

  1. Method to make a single-step etch mask for 3D monolithic nanostructures

    NARCIS (Netherlands)

    Grishina, Diana; Harteveld, Cornelis A.M.; Woldering, L.A.; Vos, Willem L.

    2015-01-01

    Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to

  2. Surface plasmon-enhanced amplified spontaneous emission from organic single crystals by integrating graphene/copper nanoparticle hybrid nanostructures.

    Science.gov (United States)

    Li, Yun-Fei; Feng, Jing; Dong, Feng-Xi; Ding, Ran; Zhang, Zhen-Yu; Zhang, Xu-Lin; Chen, Yang; Bi, Yan-Gang; Sun, Hong-Bo

    2017-12-14

    Organic single crystals have attracted great attention because of their advantages such as high carrier mobility and high thermal stability. Amplified spontaneous emission (ASE) is an important parameter for the optoelectronic applications of organic single crystals. Here, surface plasmon-enhanced ASE from the organic single crystals has been demonstrated by integrating graphene/copper nanoparticle (Cu NP) hybrid nanostructures. Graphene is fully accommodating to the topography of Cu NPs by the transfer-free as-grown method for the configuration of the hybrid nanostructures, which makes full electrical contact and strong interactions between graphene and the local electric field of surface plasmon resonances. The enhanced localized surface plasmon resonances induced by the hybrid nanostructures result in an enhanced intensity and lowered threshold of ASE from the organic single crystals. Moreover, the as-grown graphene sheets covering fully and uniformly on the Cu NPs act as a barrier against oxidation, and results in an enhanced stability of the fluorescence from the crystals.

  3. Single-crystalline Aluminum Nanostructures on Semiconducting GaAs Substrate for Ultraviolet to Near-infrared Plasmonics

    OpenAIRE

    Liu, Hsuan-Wei; Lin, Fan-Cheng; Lin, Shi-Wei; Wu, Jau-Yang; Lin, Sheng-Di; Huang, Jer-Shing

    2014-01-01

    Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and excels noble metals in the natural abundance, cost and compatibility with modern semiconductor fabrication process. Here, we present UV to near-infrared (NIR) plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam (FIB) milling into...

  4. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    methoxy benzoate (C4MB) single crystals were successfully grown by the slow evaporation solution growth technique. The harvested crystals were subjected to single-crystal X-ray diffraction, spectral, optical, thermal and mechanical studies in ...

  5. Growth of Ag, Au, Cu, and Pt nanostructures on surfaces by micropatterned laser-image formations

    Science.gov (United States)

    Pacheco-Londono, Leonardo C.; Aparicio-Bolaño, Joaquín.; Primera-Pedrozo, Oliva M.; Hernandez-Rivera, Samuel P.

    2011-07-01

    Silver, gold, copper and platinum nanoparticles (NPs) were grown on surfaces in the form of patterns by the exposure of laser radiation onto droplets of metal ion solutions and the aid of a reducing agent. The generation of patterns from metallic NPs was achieved by combining induced growth of NPs and nanostructures by laser incidence directly on surfaces and optical image formation techniques for transferring the patterns. Near-UV (363.8nm) and visible (532nm) laser wavelengths were used for the laser-induced growth of NPs into microstructures on glass, quartz, stainless steel, silicon, and gold-on-silicon substrates. The sizes of the patterns formed were on the micrometer scale and the sizes of the transferred patterns were on the millimeter scale. The patterns formed were generated by optical transference of image and interference of laser beams. Ag and Au substrates were highly active in surface enhanced Raman spectroscopy (SERS). The enhanced Raman activity was measured for SERS probe molecules: 9H-purin-6-amine (adenine) and 1,2-bis (4-pyridyl)-ethane analytes on Ag and Au substrates, respectively. The enhancement factors obtained were 1.8×105 and 6.2×106, respectively.

  6. Hydrothermal synthesis of nanostructured SnO particles through crystal growth in the presence of gelatin

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, Hiroaki, E-mail: h_uchi@kansai-u.ac.jp; Nakanishi, Shunsuke; Kozuka, Hiromitsu

    2014-09-15

    Crystalline SnO particles were obtained from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment in aqueous solutions containing gelatin at 150 °C for 24 h, where the morphologies of the SnO products changed from blocks to layered disks, stacked plates and unshaped aggregates with increasing amount of gelatin in the solutions. Such morphological changes of SnO particles were thought to be attributed to the suppression of the growth of SnO crystals by the adsorbed gelatin. - Graphical abstract: Nanostructured SnO particles were obtained from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment in gelatin solutions. - Highlights: • SnO particles were prepared from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment. • The adsorption of gelatin suppressed the growth of SnO crystals. • The shape of SnO particles depends on the amount of gelatin. • Blocks, disks, stacked plates and unshaped aggregates were obtained.

  7. Molecular Processes Studied at a Single-Molecule Level Using DNA Origami Nanostructures and Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Ilko Bald

    2014-09-01

    Full Text Available DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates.

  8. Growth and anisotropic transport properties of self-assembled InAs nanostructures in InP

    Energy Technology Data Exchange (ETDEWEB)

    Bierwagen, O.

    2007-12-20

    Self-assembled InAs nanostructures in InP, comprising quantum wells, quantum wires, and quantum dots, are studied in terms of their formation and properties. In particular, the structural, optical, and anisotropic transport properties of the nanostructures are investigated. The focus is a comprehending exploration of the anisotropic in-plane transport in large ensembles of laterally coupled InAs nanostructures. The self-assembled Stranski-Krastanov growth of InAs nanostructures is studied by gas-source molecular beam epitaxy on both nominally oriented and vicinal InP(001). Optical polarization of the interband transitions arising from the nanostructure type is demonstrated by photoluminescence and transmission spectroscopy. The experimentally convenient four-contact van der Pauw Hall measurement of rectangularly shaped semiconductors, usually applied to isotropic systems, is extended to yield the anisotropic transport properties. Temperature dependent transport measurements are performed in large ensembles of laterally closely spaced nanostructures. The transport of quantum wire-, quantum dash- and quantum dot containing samples is highly anisotropic with the principal axes of conductivity aligned to the <110> directions. The direction of higher mobility is [ anti 110], which is parallel to the direction of the quantum wires. In extreme cases, the anisotropies exceed 30 for electrons, and 100 for holes. The extreme anisotropy for holes is due to diffusive transport through extended states in the [ anti 110], and hopping transport through laterally localized states in the [110] direction, within the same sample. A novel 5-terminal electronic switching device based on gate-controlled transport anisotropy is proposed. The gate-control of the transport anisotropy in modulation-doped, self-organized InAs quantum wires embedded in InP is demonstrated. (orig.)

  9. Growth and anisotropic transport properties of self-assembled InAs nanostructures in InP

    International Nuclear Information System (INIS)

    Bierwagen, O.

    2007-01-01

    Self-assembled InAs nanostructures in InP, comprising quantum wells, quantum wires, and quantum dots, are studied in terms of their formation and properties. In particular, the structural, optical, and anisotropic transport properties of the nanostructures are investigated. The focus is a comprehending exploration of the anisotropic in-plane transport in large ensembles of laterally coupled InAs nanostructures. The self-assembled Stranski-Krastanov growth of InAs nanostructures is studied by gas-source molecular beam epitaxy on both nominally oriented and vicinal InP(001). Optical polarization of the interband transitions arising from the nanostructure type is demonstrated by photoluminescence and transmission spectroscopy. The experimentally convenient four-contact van der Pauw Hall measurement of rectangularly shaped semiconductors, usually applied to isotropic systems, is extended to yield the anisotropic transport properties. Temperature dependent transport measurements are performed in large ensembles of laterally closely spaced nanostructures. The transport of quantum wire-, quantum dash- and quantum dot containing samples is highly anisotropic with the principal axes of conductivity aligned to the directions. The direction of higher mobility is [ anti 110], which is parallel to the direction of the quantum wires. In extreme cases, the anisotropies exceed 30 for electrons, and 100 for holes. The extreme anisotropy for holes is due to diffusive transport through extended states in the [ anti 110], and hopping transport through laterally localized states in the [110] direction, within the same sample. A novel 5-terminal electronic switching device based on gate-controlled transport anisotropy is proposed. The gate-control of the transport anisotropy in modulation-doped, self-organized InAs quantum wires embedded in InP is demonstrated. (orig.)

  10. Growth features of ammonium hydrogen d-tartrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    Ammonium hydrogen d-tartrate (d-AHT) single crystals were grown in silica gel. The growth fea- tures of these crystals with variation of parameters like specific gravity of the gel, gel pH, acid concentrations, concentration of the feed solution and gel age were studied in detail. Keywords. d-AHT single crystals; growth features ...

  11. Implications for photonic applications of diatom growth and frustule nanostructure changes in response to different light wavelengths

    DEFF Research Database (Denmark)

    Su, Yanyan; Lundholm, Nina; Friis, Søren Michael Mørk

    2015-01-01

    in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an important role in mediatin g light for these biological functions, as well as being central for its nano - technological...... applications. In this study, we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light (red, yellow, green and blue) at 300 μmol photons m - 2 s - 1 resulted in a statistically...... significant change in nanostructure compared to white light. Green light at 100 μmol photon m - 2 s - 1 led to a significant dec rease in mean frustule diameter and mean foramen diameter. Numerical simulations confirmed that the morphological changes obtained were sufficient to induce clear differences...

  12. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  13. Single-Crystalline Aluminum Nanostructures on a Semiconducting GaAs Substrate for Ultraviolet to Near-Infrared Plasmonics.

    Science.gov (United States)

    Liu, Hsuan-Wei; Lin, Fan-Cheng; Lin, Shi-Wei; Wu, Jau-Yang; Chou, Bo-Tsun; Lai, Kuang-Jen; Lin, Sheng-Di; Huang, Jer-Shing

    2015-04-28

    Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and is superior to noble metals in natural abundance, cost, and compatibility with modern semiconductor fabrication processes. Ultrasmooth single-crystalline metallic films are beneficial for the fabrication of high-definition plasmonic nanostructures, especially complex integrated nanocircuits. The absence of surface corrugation and crystal boundaries also guarantees superior optical properties and applications in nanolasers. Here, we present UV to near-infrared plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam milling into an ultrasmooth single-crystalline aluminum film grown on a semiconducting GaAs substrate with a molecular beam epitaxy method. The single-crystalline aluminum film shows improved reflectivity and reduced two-photon photoluminescence (TPPL) due to the ultrasmooth surface. Both linear scattering and nonlinear TPPL are studied in detail. The nanoslit arrays show clear Fano-like resonance, and the nanoholes are found to support both photonic modes and localized surface plasmon resonance. We also found that TPPL generation is more efficient when the excitation polarization is parallel rather than perpendicular to the edge of the aluminum film. Such a counterintuitive phenomenon is attributed to the high refractive index of the GaAs substrate. We show that the polarization of TPPL from aluminum preserves the excitation polarization and is independent of the crystal orientation of the film or substrate. Our study gains insight into the optical property of aluminum nanostructures on a high-index semiconducting GaAs substrate and illustrates a practical route to implement plasmonic devices onto semiconductors for future hybrid nanodevices.

  14. The growth of Sea-urchin-like AlN nanostructures by modified CVD and their Field Emission properties

    Science.gov (United States)

    Guo, Lu`an; Chen, Guangde; Zhu, Youzhang; Duan, Xiangyang; Ye, Honggang

    2015-09-01

    AlN complex nanostructures were fabricated by using chemical vapor deposition (CVD) method which was carried out at a low moderate temperature ( 750 °C) and without any catalyst. Field emission scanning electron microscopy (FESEM), X-Ray diffraction, transmission electron microscopy (TEM), and Raman scattering spectrum were used to characterize the microstructures and morphologies of the products. The FESEM results of samples exhibit unordered nanoneedle lawn-like interspersed by the Sea-urchin-like morphology, in which many needle-like nanostructures with the length of 500 nm grow radially from a central nucleus. The results of the X-ray, TEM and Raman scattering spectrum indicate that the samples have a preferential growth along the [0001] direction good quality AlN nanostructure. The field emission device testing shows that the Sea-urchin-like nanostructure has a very low turn-on electric field of 3.6 V/μm (0.01 mA/cm2) and a very high field enhancement factor β (2.1×103) at room temperature. It suggests that it can be used for field emission displays and vacuum microelectronic devices.

  15. Nanostructured molybdenum oxide-based antibacterial paint: effective growth inhibition of various pathogenic bacteria

    Science.gov (United States)

    Krishnamoorthy, Karthikeyan; Premanathan, Mariappan; Veerapandian, Murugan; Kim, Sang Jae

    2014-08-01

    The prevention of bacterial infections in the health care environment is paramount to providing better treatment. Covering a susceptible environment with an antimicrobial coating is a successful way to avoid bacterial growth. Research on the preparation of durable antimicrobial coatings is promising for both fundamental surface care and clinical care applications. Herein, we report a facile, efficient, and scalable preparation of MoO3 paint using a cost-effective ball-milling approach. The MoO3 nanoplates (synthesized by thermal decomposition of ammonium heptamolybdate) are used as a pigment and antibacterial activity moiety in alkyd resin binders and other suitable eco-friendly additives in the preparation of paint. Surface morphology, chemical states, bonding nature, and intermolecular interaction between the MoO3 and the alkyd resin were studied using Raman and x-ray photoelectron spectroscopic analysis. The antibacterial properties of a prepared MoO3 nanoplate against various bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae) was determined using the microdilution method. Bacterial strains exposed to an MoO3 paint coated surface exhibit a significant loss of viability in a time-dependent manner. Fundamental modes of antibacterial activities ascribed from a biocompatible and durable MoO3 nanostructure incorporated into an alkyd resin complex are discussed. The obtained experimental findings suggest the potential utility of prepared MoO3-based paint coating for the prevention of health care associated infections.

  16. Nanostructured molybdenum oxide-based antibacterial paint: effective growth inhibition of various pathogenic bacteria

    International Nuclear Information System (INIS)

    Krishnamoorthy, Karthikeyan; Premanathan, Mariappan; Veerapandian, Murugan; Jae Kim, Sang

    2014-01-01

    The prevention of bacterial infections in the health care environment is paramount to providing better treatment. Covering a susceptible environment with an antimicrobial coating is a successful way to avoid bacterial growth. Research on the preparation of durable antimicrobial coatings is promising for both fundamental surface care and clinical care applications. Herein, we report a facile, efficient, and scalable preparation of MoO 3 paint using a cost-effective ball-milling approach. The MoO 3 nanoplates (synthesized by thermal decomposition of ammonium heptamolybdate) are used as a pigment and antibacterial activity moiety in alkyd resin binders and other suitable eco-friendly additives in the preparation of paint. Surface morphology, chemical states, bonding nature, and intermolecular interaction between the MoO 3 and the alkyd resin were studied using Raman and x-ray photoelectron spectroscopic analysis. The antibacterial properties of a prepared MoO 3 nanoplate against various bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae) was determined using the microdilution method. Bacterial strains exposed to an MoO 3 paint coated surface exhibit a significant loss of viability in a time-dependent manner. Fundamental modes of antibacterial activities ascribed from a biocompatible and durable MoO 3 nanostructure incorporated into an alkyd resin complex are discussed. The obtained experimental findings suggest the potential utility of prepared MoO 3 -based paint coating for the prevention of health care associated infections. (paper)

  17. Single-step rapid assembly of DNA origami nanostructures for addressable nanoscale bioreactors

    DEFF Research Database (Denmark)

    Fu, Yanming; Zeng, Dongdong; Chao, Jie

    2013-01-01

    Self-assembled DNA origami nanostructures have shown great promise for bottom-up construction of complex objects with nanoscale addressability. Here we show that DNA origami-based 1D nanoribbons and nanotubes are one-pot assembled with controllable sizes and nanoscale addressability with high speed...... (within only 10-20 min), exhibiting extraordinarily high cooperativity that is often observed in assembly of natural molecular machines in cells (e.g. ribosome). By exploiting the high specificity of DNA-based self-assembly, we can precisely anchor proteins on these DNA origami nanostructures with sub-10...

  18. Theoretical studies of growth processes and electronic properties of nanostructures on surfaces

    Science.gov (United States)

    Mo, Yina

    Low dimensional nanostructures have been of particular interest because of their potential applications in both theoretical studies and industrial use. Although great efforts have been put into obtaining better understanding of the formation and properties of these materials, many questions still remain unanswered. This thesis work has focused on theoretical studies of (1) the growth processes of magnetic nanowires on transition-metal surfaces, (2) the dynamics of pentacene thin-film growth and island structures on inert surfaces, and (3) our proposal of a new type of semiconducting nanotube. In the first study, we elucidated a novel and intriguing kinetic pathway for the formation of Fe nanowires on the upper edge of a monatomic-layer-high step on Cu(111) using first-principles calculations. The identification of a hidden fundamental Fe basal line within the Cu steps prior to the formation of the apparent upper step edge Fe wire produces a totally different view of step-decorating wire structures and offers new possibilities for the study of the properties of these wires. Subsequent experiments with scanning tunneling microscopy unambiguously established the essential role of embedded Fe atoms as precursors to monatomic wire growth. A more general study of adatom behavior near transition-metal step edges illustrated a systematic trend in the adatom energetics and kinetics, resulted from the electronic interactions between the adatom and the surfaces. This work opens the possibility of controlled manufacturing of one-dimensional nanowires. In the second study, we investigated pentacene thin-films on H-diamond, H-silica and OH-silica surfaces via force field molecular dynamics simulations. Pentacene island structures on these surfaces were identified and found to have a 90-degree rotation relative to the structure proposed by some experimental groups. Our work may facilitate the design and control of experimental pentacene thin-film growth, and thus the development

  19. Assembling three-dimensional nanostructures on metal surfaces with a reversible vertical single-atom manipulation: A theoretical modeling

    International Nuclear Information System (INIS)

    Yang Tianxing; Ye Xiang; Huang Lei; Xie Yiqun; Ke Sanhuang

    2012-01-01

    Highlights: ► We simulate the reversible vertical single-atom manipulations on several metal surfaces. ► We propose a method to predict whether a reversible vertical single-atom manipulation can be successful on several metal surfaces. ► A 3-dimensional Ni nanocluster is assembled on the Ni(1 1 1) surface using a Ni trimer-apex tip. - Abstract: We propose a theoretical model to show that pulling up an adatom from an atomic step requires a weaker force than from the flat surfaces of Al(0 0 1), Ni(1 1 1), Pt(1 1 0) and Au(1 1 0). Single adatom in the atomic step can be extracted vertically by a trimer-apex tip while can be released to the flat surface. This reversible vertical manipulation can then be used to fabricate a supported three-dimensional (3D) nanostructure on the Ni(1 1 1) surface. The present modeling can be used to predict whether the reversible vertical single-atom manipulation and thus the assembling of 3D nanostructures can be achieved on a metal surface.

  20. Systematic Investigation of Controlled Nanostructuring of Mn 12 Single-Molecule Magnets Templated by Metal–Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Aulakh, Darpandeep [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States; Xie, Haomiao [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Shen, Zhe [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Harley, Alexander [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States; Zhang, Xuan [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States; Yakovenko, Andrey A. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States; Dunbar, Kim R. [Department of Chemistry, Texas A& amp,M University, College Station, Texas 77845, United States; Wriedt, Mario [Department of Chemistry; amp, Biomolecular Science, Clarkson University, Potsdam, New York 13699, United States

    2017-05-25

    This is the first systematic study exploring metal–organic frameworks (MOFs) as platforms for the controlled nanostructuring of molecular magnets. We report the incorporation of seven single-molecule magnets (SMMs) of general composition [Mn12O12(O2CR)16(OH2)4], with R = CF3 (1), (CH3)CCH2 (2), CH2Cl (3), CH2Br (4), CHCl2 (5), CH2But (6), and C6H5 (7), into the hexagonal channel pores of a mesoporous MOF host. The resulting nanostructured composites combine the key SMM properties with the functional properties of the MOF. Synchrotron-based powder diffraction with difference envelope density analysis, physisorption analysis (surface area and pore size distribution), and thermal analyses reveal that the well-ordered hexagonal structure of the host framework is preserved, and magnetic measurements indicate that slow relaxation of the magnetization, characteristic of the corresponding Mn12 derivative guests, occurs inside the MOF pores. Structural host–guest correlations including the bulkiness and polarity of peripheral SMM ligands are discussed as fundamental parameters influencing the global SMM@MOF loading capacities. These results demonstrate that employing MOFs as platforms for the nanostructuration of SMMs is not limited to a particular host–guest system but potentially applicable to a multitude of other molecular magnets. Such fundamental findings will assist in paving the way for the development of novel advanced spintronic devices.

  1. Growth-morphology-luminescence correlation in ZnO-containing nanostructures synthesized in different media

    International Nuclear Information System (INIS)

    Japic, Dajana; Antonio Paramo, J.; Marinsek, Marjan; Strzhemechny, Yuri M.; Crnjak Orel, Zorica

    2012-01-01

    Zinc hydroxide particles were prepared by a two-step process employing zinc nitrate hexahydrate, urea, ethylene glycol, water and p-toluene-sulfonic acid monohydrate (p-TSA). We used different concentrations of the reactants as well as different volume ratios of the solvents. ZnO particles were obtained by thermal treatment of the reaction products at two different temperatures: 350 °C and 500 °C. The samples were characterized by scanning field emission electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, BET analysis, thermogravimetry (TG) analysis and photoluminescence (PL) spectroscopy. It was found that after the thermal treatment particles become smaller, with the p-TSA concentration strongly affecting the morphology of the particles. Luminescence properties of the samples probed by PL at 8 K and room temperature exhibited a remarkable correlation with specimens′ nanomorphology. Luminescent features at ∼2.0–2.2 eV, ∼2.4–2.5 eV, ∼2.65 eV, ∼2.9 eV, ∼3.0–3.1 eV and ∼3.3 eV were observed in most specimens, although their relative intensity and temperature dependence were specific to an individual group of samples vis-à-vis their growth history and morphology. - Highlights: ► ZnO-containing nanostructures grown by precipitation were investigated. ► Samples' morphology can be carefully tailored via growth control parameters. ► Strong dependence of optoelectronic properties on specimens' morphology was observed. ► Efficient control of composition, morphology and luminescence via synthesis parameters.

  2. Decoration of ZnO Nanorods with Coral Reefs like NiO Nanostructures by the Hydrothermal Growth Method and Their Luminescence Study

    Directory of Open Access Journals (Sweden)

    Mazhar Ali Abbasi

    2014-01-01

    Full Text Available Composite nanostructures of coral reefs like p-type NiO/n-type ZnO were synthesized on fluorine-doped tin oxide glass substrates by hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. This investigation shows that the adopted synthesis leads to high crystalline quality nanostructures. The morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL spectra for the synthesized composite nanostructures are dominated mainly by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence of the decorated ZnO nanostructures is enhanced by the presence of the NiO.

  3. Effect of growth parameters on the optical properties of ZnO nanostructures grown by simple solution methods

    Science.gov (United States)

    Kothari, Anjana

    2017-05-01

    ZnO, a wide band gap semiconductor is of significant interest for a range of practical applications. One of the highly attractive features of ZnO is to grow variety of nanostructures by using low-cost techniques. In this paper, we report deposition of ZnO nanostructure rod-arrays (NRA) via low-temperature, solution-based deposition techniques such as chemical bath deposition (CBD) and microwave-assisted chemical bath deposition (MACBD). A detailed study of film deposition parameters such as variation in concentration of precursors and deposition temperature has been carried out. Compositional and structural study of the films has been done by X-ray Diffractometer to know the phase and purity of the final product. Morphological study of these structures has been carried out by Scanning Electron Microscopy. Optical study such as transmittance and diffuse reflectance of the films has been carried out as a function of growth parameters.

  4. Growth and characterization of nanostructured CuO films via CBD approach for oxygen gas sensing

    Science.gov (United States)

    Nurfazliana, M. F.; Sahdan, M. Z.; Saim, H.

    2017-01-01

    Nanostructured copper oxide (CuO) films were grown on portable IDE circuit silicon-based by low-cost chemical bath deposition (CBD) technique at three different deposition times (3 h, 5 h and 7 h). The effect of deposition times on the morphological, structural, optical and sensing properties of the nanostructured films were investigated. From the morphological and structural properties, the nanostructured film deposited at 5 h was found to have homogenous surface of CuO nanowhiskers and high crystallinity with tenorite phase compared to 3 h and 7 h films. Besides, there is no heat treatment required in order to produce CuO nanostructures film with tenorite phase. The sensing response (resistance changes) of as-synthesized films to concentration of oxygen (O2) gas also was compared. Film resistance of CuO nanostructures was studied in an environment of dry air loaded (gas sensor chamber) with 30 % of O2 gas. The results revealed that the deposition time causes significant effect on the sensing performance of nanostructured CuO to O2 gas.

  5. Reducing Staphylococcus aureus growth on Ti alloy nanostructured surfaces through the addition of Sn.

    Science.gov (United States)

    Verissimo, Nathália C; Geilich, Benjamin M; Oliveira, Haroldo G; Caram, Rubens; Webster, Thomas J

    2015-12-01

    β-type Ti alloys containing Nb are exciting materials for numerous orthopedic and dental applications due to their exceptional mechanical properties. To improve their cytocompatibility properties (such as increasing bone growth and decreasing infection), the surfaces of such materials can be optimized by adding elements and/or nanotexturing through anodization. Because of the increasing prevalence of orthopedic implant infections, the objective of this in vitro study was to add Sn and create unique nanoscale surface features on β-type Ti alloys. Nanotubes and nanofeatures on Ti-35Nb and Ti-35Nb-4Sn alloys were created by anodization in a HF-based electrolyte and then heat treated in a furnace to promote amorphous structures and phases such as anatase, a mixture of anatase-rutile, and rutile. Samples were characterized by SEM, which indicated different morphologies dependent on the oxide content and method of modification. XPS experiments identified the oxide content which resulted in a phase transformation in the oxide layer formed onto Ti-35Nb and Ti-35Nb-4Sn alloys. Most importantly, regardless of the resulting nanostructures (nanotubes or nanofeatures) and crystalline phase, this study showed for the first time that adding Sn to β-type Ti alloys strongly decreased the adhesion of Staphylococcus aureus (S. aureus; a bacteria which commonly infects orthopedic implants leading to their failure). Thus, this study demonstrated that β-type Ti alloys with Nb and Sn have great promise to improve numerous orthopedic applications where infection may be a concern. © 2015 Wiley Periodicals, Inc.

  6. Facile and green fabrication of organic single-crystal hollow micro/nanostructures.

    Science.gov (United States)

    Yang, Jun; Chen, Yingzhi; Zhang, Xiujuan; Ou, Xuemei; Zhang, Xiaohong

    2011-07-15

    Under high humidity and appropriate temperature, tris (8-hydroxyquinoline) aluminum (Alq3) solid micro/nanostructures may be etched into hollow structures and still retain their crystalline structures and surface morphologies. The shapes and sizes of the hollow structures are easily adjusted by varying the experimental parameters. Throughout the entire process, water is introduced into the system instead of organic or corrosive solvents, making this method convenient and environmentally friendly; it can also be extended to application in other materials such as TCNQ.

  7. Single ion induced surface nanostructures: a comparison between slow highly charged and swift heavy ions.

    Science.gov (United States)

    Aumayr, Friedrich; Facsko, Stefan; El-Said, Ayman S; Trautmann, Christina; Schleberger, Marika

    2011-10-05

    This topical review focuses on recent advances in the understanding of the formation of surface nanostructures, an intriguing phenomenon in ion-surface interaction due to the impact of individual ions. In many solid targets, swift heavy ions produce narrow cylindrical tracks accompanied by the formation of a surface nanostructure. More recently, a similar nanometric surface effect has been revealed for the impact of individual, very slow but highly charged ions. While swift ions transfer their large kinetic energy to the target via ionization and electronic excitation processes (electronic stopping), slow highly charged ions produce surface structures due to potential energy deposited at the top surface layers. Despite the differences in primary excitation, the similarity between the nanostructures is striking and strongly points to a common mechanism related to the energy transfer from the electronic to the lattice system of the target. A comparison of surface structures induced by swift heavy ions and slow highly charged ions provides a valuable insight to better understand the formation mechanisms. © 2011 IOP Publishing Ltd

  8. Synthesis of ferroelectric nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Roervik, Per Martin

    2008-12-15

    The increasing miniaturization of electric and mechanical components makes the synthesis and assembly of nanoscale structures an important step in modern technology. Functional materials, such as the ferroelectric perovskites, are vital to the integration and utility value of nanotechnology in the future. In the present work, chemical methods to synthesize one-dimensional (1D) nanostructures of ferroelectric perovskites have been studied. To successfully and controllably make 1D nanostructures by chemical methods it is very important to understand the growth mechanism of these nanostructures, in order to design the structures for use in various applications. For the integration of 1D nanostructures into devices it is also very important to be able to make arrays and large-area designed structures from the building blocks that single nanostructures constitute. As functional materials, it is of course also vital to study the properties of the nanostructures. The characterization of properties of single nanostructures is challenging, but essential to the use of such structures. The aim of this work has been to synthesize high quality single-crystalline 1D nanostructures of ferroelectric perovskites with emphasis on PbTiO3 , to make arrays or hierarchical nanostructures of 1D nanostructures on substrates, to understand the growth mechanisms of the 1D nanostructures, and to investigate the ferroelectric and piezoelectric properties of the 1D nanostructures. In Paper I, a molten salt synthesis route, previously reported to yield BaTiO3 , PbTiO3 and Na2Ti6O13 nanorods, was re-examined in order to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titanium was annealed in the presence of NaCl at 760 degrees Celsius or 820 degrees Celsius. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was

  9. Growth features of ammonium hydrogen d-tartrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    Most of the tartrate compounds are insoluble in water and decompose before melting. Hence, single crystals of such type cannot be grown either by slow evaporation or by melt technique, but can be grown easily by gel method. Gel method is an alternative method to solution growth with controlled diffusion and the growth ...

  10. Enhanced sensitivity in non-enzymatic glucose detection by improved growth kinetics of Ni-based nanostructures

    Science.gov (United States)

    Urso, M.; Pellegrino, G.; Strano, V.; Bruno, E.; Priolo, F.; Mirabella, S.

    2018-04-01

    Ni-based nanostructures are attractive catalytic materials for many electrochemical applications, among which are non-enzymatic sensing, charge storage, and water splitting. In this work, we clarify the synthesis kinetics of Ni(OH)2/NiOOH nanowalls grown by chemical bath deposition at room temperature and at 50 °C. We applied the results to non-enzymatic glucose sensing, reaching a highest sensitivity of 31 mA cm-2mM-1. Using scanning electron microscopy, x-ray diffraction analysis and Rutherford backscattering spectrometry we found that the growth occurs through two regimes: first, a quick random growth leading to disordered sheets of Ni oxy-hydroxide, followed by a slower growth of well-aligned sheets of Ni hydroxide. A high growth temperature (50 °C), leading mainly to well-aligned sheets, offers superior electrochemical properties in terms of charge storage, charge carrier transport and catalytic action, as confirmed by cyclic voltammetry and electrochemical impedance spectroscopy analyses. The reported results on the optimization and application of low-cost synthesis of these Ni-based nanostructures have a large potential for application in catalysis, (bio)sensing, and supercapacitors areas.

  11. Single-step fabrication of electrodes with controlled nanostructured surface roughness using optically-induced electrodeposition

    Science.gov (United States)

    Liu, N.; Li, M.; Liu, L.; Yang, Y.; Mai, J.; Pu, H.; Sun, Y.; Li, W. J.

    2018-02-01

    The customized fabrication of microelectrodes from gold nanoparticles (AuNPs) has attracted much attention due to their numerous applications in chemistry and biomedical engineering, such as for surface-enhanced Raman spectroscopy (SERS) and as catalyst sites for electrochemistry. Herein, we present a novel optically-induced electrodeposition (OED) method for rapidly fabricating gold electrodes which are also surface-modified with nanoparticles in one single step. The electrodeposition mechanism, with respect to the applied AC voltage signal and the elapsed deposition time, on the resulting morphology and particle sizes was investigated. The results from SEM and AFM analysis demonstrated that 80-200 nm gold particles can be formed on the surface of the gold electrodes. Simultaneously, both the size of the nanoparticles and the roughness of the fabricated electrodes can be regulated by the deposition time. Compared to state-of-the-art methods for fabricating microelectrodes with AuNPs, such as nano-seed-mediated growth and conventional electrodeposition, this OED technique has several advantages including: (1) electrode fabrication and surface modification using nanoparticles are completed in a single step, eliminating the need for prefabricating micro electrodes; (2) the patterning of electrodes is defined using a digitally-customized, projected optical image rather than using fixed physical masks; and (3) both the fabrication and surface modification processes are rapid, and the entire fabrication process only requires less than 6 s.

  12. Development of novel growth methods for halide single crystals

    Science.gov (United States)

    Yokota, Yuui; Kurosawa, Shunsuke; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2017-03-01

    We developed novel growth methods for halide scintillator single crystals with hygroscopic nature, Halide micro-pulling-down [H-μ-PD] method and Halide Vertical Bridgman [H-VB] method. The H-μ-PD method with a removable chamber system can grow a single crystal of halide scintillator material with hygroscopicity at faster growth rate than the conventional methods. On the other hand, the H-VB method can grow a large bulk single crystal of halide scintillator without a quartz ampule. CeCl3, LaBr3, Ce:LaBr3 and Eu:SrI2 fiber single crystals could be grown by the H-μ-PD method and Eu:SrI2 bulk single crystals of 1 and 1.5 inch in diameter could be grown by the H-VB method. The grown fiber and bulk single crystals showed comparable scintillation properties to the previous reports using the conventional methods.

  13. In situ inward epitaxial growth of bulk macroporous single crystals.

    Science.gov (United States)

    Chen, Chenlong; Sun, Shujing; Chou, Mitch M C; Xie, Kui

    2017-12-19

    The functionalities of porous materials could be significantly enhanced if the materials themselves were in single-crystal form, which, owing to structural coherence, would reduce electronic and optical scattering effects. However, growing macroporous single crystals remains a fundamental challenge, let alone manufacturing crystals large enough to be of practical use. Here we demonstrate a straightforward, inexpensive, versatile method for creating macroporous gallium nitride single crystals on a centimetre scale. The synthetic strategy is built upon a disruptive crystal growth mechanism that utilises direct nitridation of a parent LiGaO 2 single crystal rendering an inward epitaxial growth process. Strikingly, the resulting single crystals exhibit electron mobility comparable to that for bulk crystals grown by the conventional sodium flux method. This approach not only affords control of both crystal and pore size through synthetic modification, but proves generic, thus opening up the possibility of designing macroporous crystals in a wealth of other materials.

  14. Manganese Nanostructures and Magnetism

    Science.gov (United States)

    Simov, Kirie Rangelov

    The primary goal of this study is to incorporate adatoms with large magnetic moment, such as Mn, into two technologically significant group IV semiconductor (SC) matrices, e.g. Si and Ge. For the first time in the world, we experimentally demonstrate Mn doping by embedding nanostructured thin layers, i.e. delta-doping. The growth is observed by in-situ scanning tunneling microscopy (STM), which combines topographic and electronic information in a single image. We investigate the initial stages of Mn monolayer growth on a Si(100)(2x1) surface reconstruction, develop methods for classification of nanostructure types for a range of surface defect concentrations (1.0 to 18.2%), and subsequently encapsulate the thin Mn layer in a SC matrix. These experiments are instrumental in generating a surface processing diagram for self-assembly of monoatomic Mn-wires. The role of surface vacancies has also been studied by kinetic Monte Carlo modeling and the experimental observations are compared with the simulation results, leading to the conclusion that Si(100)(2x1) vacancies serve as nucleation centers in the Mn-Si system. Oxide formation, which happens readily in air, is detrimental to ferromagnetism and lessens the magnetic properties of the nanostructures. Therefore, the protective SC cap, composed of either Si or Ge, serves a dual purpose: it is both the embedding matrix for the Mn nanostructured thin film and a protective agent for oxidation. STM observations of partially deposited caps ensure that the nanostructures remain intact during growth. Lastly, the relationship between magnetism and nanostructure types is established by an in-depth study using x-ray magnetic circular dichroism (XMCD). This sensitive method detects signals even at coverages less than one atomic layer of Mn. XMCD is capable of discerning which chemical compounds contribute to the magnetic moment of the system, and provides a ratio between the orbital and spin contributions. Depending on the amount

  15. Photoluminescence quenching, structures, and photovoltaic properties of ZnO nanostructures decorated plasma grown single walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, Brahim, E-mail: brahim.aissa@mpbc.ca [University of Quebec, Centre Énergie, Matériaux et Télécommunications, INRS-EMT (Canada); Nedil, Mourad [Telebec Wireless Underground Communication Laboratory, UQAT (Canada); Belaidi, Abdelhak; Isaifan, Rima J. [Hamad Bin Khalifa University, Qatar Foundation, Qatar Environment and Energy Research Institute (Qatar); Bentouaf, Ali [University Hassiba Ben Bouali, Physics Department, Faculty of Science (Algeria); Fauteux, Christian; Therriault, Daniel [École Polytechnique de Montréal, Laboratory for Multiscale Mechanics (LM2), Mechanical Engineering Department (Canada)

    2017-05-15

    Zinc oxide (ZnO) nanostructures were successfully grown directly on single walled carbon nanotubes (SWCNT) template through the CO{sub 2} laser-induced chemical liquid deposition (LCLD) process. Photoluminescence (PL) of the deposited ZnO/SWCNT hybrid composites exhibits, at room temperature, a narrow near UV band located at 390 nm with no emission bands in the visible region, indicating a high degree of crystalline quality of the ZnO nanostructures. Moreover, when the relative SWCNT loads are varied within the composites, the PL intensity and the diffused optical reflectance diminish in comparison with those of ZnO alone, owing to the transfer of photo-excited electrons from ZnO to the SWCNT, and the enhancement of the optical absorbance, respectively. Finally, these ZnO/SWCNT hybrid composites are integrated into a heterojunction photovoltaic-based device, using PEDOT:PSS on ITO/glass substrate. The devices show an evident p–n junction behavior in the dark, and a clear I–V curve shift downward when illuminated with an open-circuit voltage of 1.1 V, a short circuit current density of 14.05 μA cm{sup −2}, and a fill factor of ∼35%. These results indicate that these composites fabricated via LCLD process could be promising for optoelectronic and energy-harvesting devices.

  16. Photoluminescence quenching, structures, and photovoltaic properties of ZnO nanostructures decorated plasma grown single walled carbon nanotubes

    Science.gov (United States)

    Aïssa, Brahim; Nedil, Mourad; Belaidi, Abdelhak; Isaifan, Rima J.; Bentouaf, Ali; Fauteux, Christian; Therriault, Daniel

    2017-05-01

    Zinc oxide (ZnO) nanostructures were successfully grown directly on single walled carbon nanotubes (SWCNT) template through the CO2 laser-induced chemical liquid deposition (LCLD) process. Photoluminescence (PL) of the deposited ZnO/SWCNT hybrid composites exhibits, at room temperature, a narrow near UV band located at 390 nm with no emission bands in the visible region, indicating a high degree of crystalline quality of the ZnO nanostructures. Moreover, when the relative SWCNT loads are varied within the composites, the PL intensity and the diffused optical reflectance diminish in comparison with those of ZnO alone, owing to the transfer of photo-excited electrons from ZnO to the SWCNT, and the enhancement of the optical absorbance, respectively. Finally, these ZnO/SWCNT hybrid composites are integrated into a heterojunction photovoltaic-based device, using PEDOT:PSS on ITO/glass substrate. The devices show an evident p-n junction behavior in the dark, and a clear I- V curve shift downward when illuminated with an open-circuit voltage of 1.1 V, a short circuit current density of 14.05 μA cm-2, and a fill factor of ˜35%. These results indicate that these composites fabricated via LCLD process could be promising for optoelectronic and energy-harvesting devices.

  17. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  18. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  19. Principles of crystallization, and methods of single crystal growth

    International Nuclear Information System (INIS)

    Chacra, T.

    2010-01-01

    Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

  20. Phase manipulation of Goos–Hänchen shifts in a single-layer of graphene nanostructure under strong magnetic field

    Science.gov (United States)

    Solookinejad, Gh; Jabbari, M.; Panahi, M.; Ahmadi Sangachin, E.

    2017-11-01

    In this paper, we discuss the phase management of Goos–Hänchen (GH) shifts of a probe light through a cavity with a single-layer graphene nanostructure under a strong magnetic field. By using the quantum mechanical density matrix formalism we study the GH shifts of reflected and transmitted light beams. It is realized that negative or positive GH shifts can be achieved simultaneously by tuning some controllable parameters such as relative phase and the Rabi frequency of the applied fields. Moreover, the thickness effect of the cavity structure is considered as an effective parameter for adjusting the GH shifts of reflected and transmitted light beams. We find that by choosing suitable parameters, a maximum negative shift of 4.5 mm and positive shift of 5.4 mm are possible for GH shifts in reflected and transmitted light. Our proposed model may be useful for developing all-optical devices in the infrared region.

  1. Design and Use of Nanostructured Single-Site Heterogeneous Catalysts for the Selective Transformation of Fine Chemicals

    Directory of Open Access Journals (Sweden)

    Vladimiro Dal Santo

    2010-05-01

    Full Text Available Nanostructured single-site heterogeneous catalysts possess the advantages of classical solid catalysts, in terms of easy recovery and recycling, together with a defined tailored chemical and steric environment around the catalytically active metal site. The use of inorganic oxide supports with selected shape and porosity at a nanometric level may have a relevant impact on the regio- and stereochemistry of the catalytic reaction. Analogously, by choosing the optimal preparation techniques to obtain spatially isolated and well-characterised active sites, it is possible to achieve performances that are comparable to (or, in the most favourable cases, better than those obtained with homogeneous systems. Such catalysts are therefore particularly suitable for the transformation of highly-functionalised fine chemicals and some relevant examples where high chemo-, regio- and stereoselectivity are crucial will be described.

  2. Single-step synthesis of monolithic comb-like CdS nanostructures with tunable waveguide properties.

    Science.gov (United States)

    Liu, Ruibin; Li, Zi-An; Zhang, Chunhua; Wang, Xiaoxu; Kamran, Muhammad A; Farle, Michael; Zou, Bingsuo

    2013-06-12

    Using a simple in situ seeding chemical vapor deposition (CVD) process, comb-like (branched) monolithic CdS micro/nanostructures were grown. Efficient optical coupling between the backbone and the teeth of the branched architecture is demonstrated by distributing light from an UV-laser-excited spot at one end of the backbone to all branch tips. By varying the deposition conditions, the orientation of the branches with respect to the backbone, their size and density can be tuned as well as the size of the backbone. This in situ seeding CVD method has the potential for a low-cost single-step fabrication of high-quality, micro/nanointegrated photonic devices, with tunable complex waveguiding possibilities.

  3. Two-step growth mechanism of supported Co3O4-based sea-urchin like hierarchical nanostructures

    Science.gov (United States)

    Maurizio, Chiara; Edla, Raju; Michieli, Niccolo'; Orlandi, Michele; Trapananti, Angela; Mattei, Giovanni; Miotello, Antonio

    2018-05-01

    Supported 3D hierarchical nanostructures of transition metal oxides exhibit enhanced photocatalytic performances and long-term stability under working conditions. The growth mechanisms crucially determine their intimate structure, that is a key element to optimize their properties. We report on the formation mechanism of supported Co3O4 hierarchical sea urchin-like nanostructured catalyst, starting from Co-O-B layers deposited by Pulsed Laser Deposition (PLD). The particles deposited on the layer surface, that constitute the seeds for the urchin formation, have been investigated after separation from the underneath deposited layer, by X-ray diffraction, X-ray absorption spectroscopy and scanning electron microscopy. The comparison with PLD deposited layers without O and/or B indicates a crucial role of B for the urchin formation that (i) limits Co oxidation during the deposition process and (ii) induces a chemical reduction of Co, especially in the particle core, in the first step of air annealing (2 h, 500 °C). After 2 h heating Co oxidation proceeds and Co atoms outdiffuse from the Co fcc particle core likely through fast diffusion channel present in the shell and form Co3O4 nano-needles. The growth of nano-needles from the layer beneath the particles is prevented by a faster Co oxidation and a minimum fraction of metallic Co. This investigation shows how diffusion mechanisms and chemical effects can be effectively coupled to obtain hierarchical structures of transition metal oxides.

  4. Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires

    Science.gov (United States)

    Lu, Qipeng; Wang, An-Liang; Gong, Yue; Hao, Wei; Cheng, Hongfei; Chen, Junze; Li, Bing; Yang, Nailiang; Niu, Wenxin; Wang, Jie; Yu, Yifu; Zhang, Xiao; Chen, Ye; Fan, Zhanxi; Wu, Xue-Jun; Chen, Jinping; Luo, Jun; Li, Shuzhou; Gu, Lin; Zhang, Hua

    2018-03-01

    Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au-Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.

  5. The Spatiotemporal Control of Osteoblast Cell Growth, Behavior, and Function Dictated by Nanostructured Stainless Steel Artificial Microenvironments.

    Science.gov (United States)

    Dhawan, Udesh; Pan, Hsu-An; Shie, Meng-Je; Chu, Ying Hao; Huang, Guewha S; Chen, Po-Chun; Chen, Wen Liang

    2017-12-01

    The successful application of a nanostructured biomaterial as an implant is strongly determined by the nanotopography size triggering the ideal cell response. Here, nanoporous topography on 304L stainless steel substrates was engineered to identify the nanotopography size causing a transition in the cellular characteristics, and accordingly, the design of nanostructured stainless steel surface as orthopedic implants is proposed. A variety of nanopore diameters ranging from 100 to 220 nm were fabricated by one-step electrolysis process and collectively referred to as artificial microenvironments. Control over the nanopore diameter was achieved by varying bias voltage. MG63 osteoblasts were cultured on the nanoporous surfaces for different days. Immunofluorescence (IF) and scanning electron microscopy (SEM) were performed to compare the modulation in cell morphologies and characteristics. Osteoblasts displayed differential growth parameters and distinct transition in cell behavior after nanopore reached a certain diameter. Nanopores with 100-nm diameter promoted cell growth, focal adhesions, cell area, viability, vinculin-stained area, calcium mineralization, and alkaline phosphatase activity. The ability of these nanoporous substrates to differentially modulate the cell behavior and assist in identifying the transition step will be beneficial to biomedical engineers to develop superior implant geometries, triggering an ideal cell response at the cell-nanotopography interface.

  6. Growth stimulation of Bacillus cereus and Pseudomonas putida using nanostructured ZnO thin film as transducer element

    Energy Technology Data Exchange (ETDEWEB)

    Loukanov, Alexandre, E-mail: loukanov@mail.saitama-u.ac.jp [Saitama University, Department of Chemistry, Faculty of Science (Japan); Filipov, Chavdar [University of Forestry, Department of Infectious pathology, hygiene, technology and control of food stuffs of animal origin, Faculty of Veterinary Medicine (Bulgaria); Valcheva, Violeta [Bulgarian Academy of Science, Department of Infectious Diseases, Institute of microbiology (Bulgaria); Lecheva, Marta [University of Mining and Geology “St. Ivan Rilski”, Laboratory of Engineering NanoBiotechnology, Department of Engineering Geoecology (Bulgaria); Emin, Saim [University of Nova Gorica, Materials Research Laboratory (Slovenia)

    2015-04-15

    The semiconductor zinc oxide nanomaterial (ZnO or ZnO:H) is widely used in advanced biosensor technology for the design of highly-sensitive detector elements for various applications. In the attempt to evaluate its effect on common microorganisms, two types of nanostructured transducer films have been used (average diameter 600–1000 nm). They have been prepared by using both wet sol–gel method and magnetron sputtering. Their polycrystalline structure and specific surface features have been analyzed by X-ray diffraction (XRD), scanning electron microscope, and atomic force microscope. The assessment of growth stimulation of bacteria was determined using epifluorescent microscope by cell staining with Live/Dead BacLight kit. In our experiments, the growth stimulation of Gram-positive and Gram-negative bacteria on nanostructured ZnO film is demonstrated by Bacillus cereus and Pseudomonas putida. These two bacterial species have been selected, because they are well known and studied in biosensor technologies, with structural difference of their cell walls. These pathogens are easy for with common source in the liquid food or some commercial products. Our data has revealed that the method of transducer film preparation influences strongly bacterial inhibition and division. These results present the transforming signal precisely, when ZnO is used in biosensor applications.

  7. Growth stimulation of Bacillus cereus and Pseudomonas putida using nanostructured ZnO thin film as transducer element

    Science.gov (United States)

    Loukanov, Alexandre; Filipov, Chavdar; Valcheva, Violeta; Lecheva, Marta; Emin, Saim

    2015-04-01

    The semiconductor zinc oxide nanomaterial (ZnO or ZnO:H) is widely used in advanced biosensor technology for the design of highly-sensitive detector elements for various applications. In the attempt to evaluate its effect on common microorganisms, two types of nanostructured transducer films have been used (average diameter 600-1000 nm). They have been prepared by using both wet sol-gel method and magnetron sputtering. Their polycrystalline structure and specific surface features have been analyzed by X-ray diffraction (XRD), scanning electron microscope, and atomic force microscope. The assessment of growth stimulation of bacteria was determined using epifluorescent microscope by cell staining with Live/Dead BacLight kit. In our experiments, the growth stimulation of Gram-positive and Gram-negative bacteria on nanostructured ZnO film is demonstrated by Bacillus cereus and Pseudomonas putida. These two bacterial species have been selected, because they are well known and studied in biosensor technologies, with structural difference of their cell walls. These pathogens are easy for with common source in the liquid food or some commercial products. Our data has revealed that the method of transducer film preparation influences strongly bacterial inhibition and division. These results present the transforming signal precisely, when ZnO is used in biosensor applications.

  8. On the thermal growth and properties of doped TiO2 and In2O3 elongated nanostructures and nanoplates

    International Nuclear Information System (INIS)

    Cremades, A.; Herrera, M.; Bartolomé, J.; Vásquez, G.C.; Maestre, D.; Piqueras, J.

    2014-01-01

    In this work, the driving forces behind the growth mechanisms of In 2 O 3 and TiO 2 micro- and nano-structures grown by an evaporation–solidification method are discussed. Effective or limited doping incorporation and its influence on the growth and morphology of the low dimensional structures are also assessed. A dislocation driven growth mechanism is proposed for indium oxide, indium tin oxide (ITO) and zinc doped indium oxide (IZO) nanowires. This growth mechanism is extended to the growth of IZO nano-plates. On the other hand, different low dimensional TiO 2 morphologies, mainly nanowires, needles, and bidimensional leaf-like nanostructures, have been obtained by an anisotropic induced growth. By introducing Cr in the precursor mixture, needles are formed showing stepped lateral faces related to oxygen defect stoichiometry areas as observed by EDS mapping

  9. Influence of porewidening duration on the template assisted growth of graphitic carbon nitride nanostructures

    Science.gov (United States)

    Suchitra, S. M.; Udayashankar, N. K.

    2018-01-01

    Porous anodic aluminium oxide (AAO) membranes with a highly ordered pore arrangement are typically used as ideal templates for the synthesis of numerous nanostructured materials. Highly ordered templates gained significant attraction due to the fact that they are readily fabricated through self-organised simple anodization process. In this paper, the effect of different pore-widening treatments on the quality of the pores of the AAO templates prepared with different electrolytes were inspected. Results confirmed that, without altering the interpore distance different pore dimensions and diameters of the AAO templates can be easily achieved by chemical pore widening process at room temperature. Also, graphitic carbon nitride nanorods of different dimension have been fabricated from AAO template after porewidening process. These nanostructures are widely used in case of metal free visible light driven photo catalysis, photo degradation of organic pollutants, photo electric conversion and water splitting applications.

  10. Modification of emission photon statistics from single quantum dots using metal/SiO2 core/shell nanostructures.

    Science.gov (United States)

    Naiki, Hiroyuki; Oikawa, Hidetoshi; Masuo, Sadahiro

    2017-04-12

    Emission photon statistics, i.e., single-photon and multi-photon emissions, of isolated QDs is required for tailoring optoelectronic applications. In this article, we demonstrate that the emission photon statistics can be modified by the control of the spectral overlap of the QDs with the localized surface plasmon resonance (LSPR) of the metal nanoparticle (metal NP) and by the distance between the QD and the metal NP. Moreover, the contribution to the modification of the emission photon statistics, which is the excitation and emission enhancements and the quenching generated by the spectral overlap and the distance, is elucidated. By fabricating well-defined SiO 2 -coated AgNPs and AuNPs (metal/SiO 2 ), the spectral overlap originated from the metal species of Ag and Au and the distance constituted by the thickness of the SiO 2 shell are controlled. The probability of single-photon emission of single QD was increased by the enhancement of the excitation rate via adjusting the distance using Ag/SiO 2 while the single-photon emission was converted to multi-photon emission by the effect of exciton quenching at a short distance and a small spectral overlap. By contrast, the probability of multi-photon emission was increased by enhancement of the multi-photon emission rate and the quenching via the spectral overlap using Au/SiO 2 . These results indicated the fundamental finding to control emission photon statistics in single QDs by controlling the spectral overlap and the distance, and understand the interaction of plasmonic nanostructures and single QD systems.

  11. Ultra-large single crystals by abnormal grain growth.

    Science.gov (United States)

    Kusama, Tomoe; Omori, Toshihiro; Saito, Takashi; Kise, Sumio; Tanaka, Toyonobu; Araki, Yoshikazu; Kainuma, Ryosuke

    2017-08-25

    Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by abnormal grain growth (AGG) induced by simple heat treatment with high mass productivity. In AGG, the sub-boundary energy introduced by cyclic heat treatment (CHT) is dominant in the driving pressure, and the grain boundary migration rate is accelerated by repeating the low-temperature CHT due to the increase of the sub-boundary energy. With such treatment, fabrication of single crystal bars 70 cm in length is achieved. This result ensures that the range of applications of shape memory alloys will spread beyond small-sized devices to large-scale components and may enable new applications of single crystals in other metallic and ceramics materials having similar microstructural features.Growing large single crystals cheaply and reliably for structural applications remains challenging. Here, the authors combine accelerated abnormal grain growth and cyclic heat treatments to grow a superelastic shape memory alloy single crystal to 70 cm.

  12. Controlled growth of single nanowires within a supported alumina template

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.

    2006-01-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire...

  13. Single crystal growth of europium and ytterbium based intermetallic ...

    Indian Academy of Sciences (India)

    Abstract. This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3.

  14. Single-Cell Optical Distortion Correction and Label-Free 3D Cell Shape Reconstruction on Lattices of Nanostructures.

    Science.gov (United States)

    Stephan, Jürgen; Keber, Felix; Stierle, Valentin; Rädler, Joachim O; Paulitschke, Philipp

    2017-12-13

    Imaging techniques can be compromised by aberrations. Especially when imaging through biological specimens, sample-induced distortions can limit localization accuracy. In particular, this phenomenon affects localization microscopy, traction force measurements, and single-particle tracking, which offer high-resolution insights into biological tissue. Here we present a method for quantifying and correcting the optical distortions induced by single, adherent, living cells. The technique uses periodically patterned gold nanostructures as a reference framework to quantify optically induced displacements with micrometer-scale sampling density and an accuracy of a few nanometers. The 3D cell shape and a simplified geometrical optics approach are then utilized to remap the microscope image. Our experiments reveal displacements of up to several hundred nanometers, and in corrected images these distortions are reduced by a factor of 3. Conversely, the relationship between cell shape and distortion provides a novel method of 3D cell shape reconstruction from a single image, enabling label-free 3D cell analysis.

  15. Controlling growth density and patterning of single crystalline silicon nanowires

    International Nuclear Information System (INIS)

    Chang, Tung-Hao; Chang, Yu-Cheng; Liu, Fu-Ken; Chu, Tieh-Chi

    2010-01-01

    This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

  16. Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

    Directory of Open Access Journals (Sweden)

    Tamara Aleksandrov Fabijanić

    2016-08-01

    Full Text Available The influence of grain growth inhibitors and powder size on the microstructure and mechanical properties of ultrafine and nanostructured cemented carbides was researched. Three different WC powders, with an addition of different type and content of grain growth inhibitors GGIs, VC and Cr3C2 and with dBET grain sizes in the range from 95 to 150 nm were selected as starting powders. Four different mixtures with 6 and 9 wt. % Co were prepared. The consolidated samples are characterized by different microstructural and mechanical properties with respect to the characteristics of starting powders. Increased sintering temperatures led to microstructural irregularities in the form of a discontinuous WC growth, carbide agglomerates and abnormal grain growth as a consequence of coalescence via grain boundary elimination. The addition of 0.45% Cr3C2 contributed to microstructure homogeneity, reduced discontinuous and continuous grain growth, and increased Vickers hardness by approximately 70 HV and fracture toughness by approximately 0.15 MN/m3/2. The reduction of the starting powder to a real nanosize of 95 nm resulted in lower densities, and significant hardness increase, with a simultaneously small increase in fracture toughness. The consolidation of real nanopowders (dBET < 100 nm solely by conventional sintering in hydrogen without isostatic pressing is not preferred.

  17. Effects of ZnO seed layer thickness on catalyst-free growth of ZnO nanostructures for enhanced UV photoresponse

    Science.gov (United States)

    Alsultany, Forat H.; Hassan, Z.; Ahmed, Naser M.; Elafadill, Nezar G.; Abd, Hassnen R.

    2018-01-01

    Catalyst-free growth of ZnO nanostructures were synthesized on ZnO seed layers with different thickness (25-150 nm) coated glass substrates by thermal evaporation method. Prior to the growth process, the sputtered ZnO seed layers were annealed using the continuous wave CO2 laser as a heat source at 450 °C in air for 15 min. The fabrication and characterization of a metal-semiconductor-metal ultraviolet photodetectors based on ZnO nanostructures with different thickness of seed layer were successfully fabricated. Upon exposure to 365 nm light (1.5 mW/cm2) at five-bias voltage, the device with 100 nm thick seed layer showed a relatively high UV sensitivity, quick response, and high responsivity. The prototype device shows a cost effective glass substrate using thermal evaporation method for ZnO nanostructures synthesis and demonstrates the possibility of constructing nanoscale photodetectors for nano-optics applications.

  18. Block copolymer systems: from single chain to self-assembled nanostructures.

    Science.gov (United States)

    Giacomelli, Cristiano; Schmidt, Vanessa; Aissou, Karim; Borsali, Redouane

    2010-10-19

    Recent advances in the field of macromolecular engineering applied to the fabrication of nanostructured materials using block copolymer chains as elementary building blocks are described in this feature article. By highlighting some of our work in the area and accounting for the contribution of other groups, we discuss the relationship between the physical-chemical properties of copolymer chains and the characteristics of nano-objects originating from their self-assembly in solution and in bulk, with emphasis on convenient strategies that allow for the control of composition, functionality, and topology at different levels of sophistication. In the case of micellar nanoparticles in solution, in particular, we present approaches leading to morphology selection via macromolecular architectural design, the functionalization of external solvent-philic shells with biomolecules (polysaccharides and proteins), and the maximization of micelle loading capacity by the suitable choice of solvent-phobic polymer segments. The fabrication of nanomaterials mediated by thin block copolymer films is also discussed. In this case, we emphasize the development of novel polymer chain manipulation strategies that ultimately allow for the preparation of precisely positioned nanodomains with a reduced number of defects via block-selective chemical reactivity. The challenges facing the soft matter community, the urgent demand to convert huge public and private investments into consumer products, and future possible directions in the field are also considered herein.

  19. Single potential electrodeposition of nanostructured battery materials for lithium-ion batteries

    Science.gov (United States)

    Mosby, James Matthew

    potential not only affected the crystallinity of the deposited Cu2Sb, but also the ratio of antimony to copper. The temperature of the solution bath, as well as the smoothness of the growth substrate, were found to provide control over the crystallinity of the deposited Cu2Sb. The ability to electrodeposit crystalline Cu2Sb onto a variety of conducting surfaces is uncommon for intermetallics. The ability to deposit Cu2Sb onto transmission electron microscopy (TEM) grids has allowed the investigation of the morphology, composition, and crystallinity of Cu2Sb during the nucleation and growth of the material. This investigation demonstrated that multiple transformations occur during the early stage of the nucleation of Cu2Sb. A deeper understanding of this electrodeposition procedure for this compound will be useful for extending this technique to other crystalline intermetallics. Using the procedure developed for the single potential deposition of Cu2Sb films, the information from the TEM investigation and the results of a qualitative mathematical treatment, a pulse potential deposition procedure for depositing Cu2Sb nanowire arrays was developed. This procedure leads not only to the deposition of crystalline Cu2Sb nanowires, but also to uniform filling of the templates to afford wires of uniform composition and length. After the development of the procedures for the electrodeposition of Cu2Sb films and nanowire arrays from aqueous solutions at a single potential, the battery performance of the deposited Cu2Sb was examined. The ability to directly electrodeposit Cu2Sb onto the current collector has: (1) improved the characterization of the material during the lithiation and delithiation processes, (2) decreased the weight of inactive components, and (3) allowed for the deposition of high surface area Cu2Sb. The preliminary battery testing of electrodeposited Cu2Sb supported the absence of impurities in the deposited material and demonstrated that the electrodeposited Cu2Sb

  20. Growth and Characterization on PMN-PT-Based Single Crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-07-01

    Full Text Available Lead magnesium niobate—lead titanate (PMN-PT single crystals have been successfully commercialized in medical ultrasound imaging. The superior properties of PMN-PT crystals over the legacy piezoelectric ceramics lead zirconate titanate (PZT enabled ultrasound transducers with enhanced imaging (broad bandwidth and improved sensitivity. To obtain high quality and relatively low cost single crystals for commercial production, PMN-PT single crystals were grown with modified Bridgman method, by which crystals were grown directly from stoichiometric melt without flux. For ultrasound imaging application, [001] crystal growth is essential to provide uniform composition and property within a crystal plate, which is critical for transducer performance. In addition, improvement in crystal growth technique is under development with the goals of improving the composition homogeneity along crystal growth direction and reducing unit cost of crystals. In recent years, PIN-PMN-PT single crystals have been developed with higher de-poling temperature and coercive field to provide improved thermal and electrical stability for transducer application.

  1. Inexpensive Home-Made Single Wavelength Ellipsometer (λ = 633 nm) for Measuring the Optical Constant of Nanostructured Materials

    Science.gov (United States)

    Maulana, L. Z.; Megasari, K.; Suharyadi, E.; Anugraha, R.; Abraha, K.; Santoso, I.

    2017-05-01

    Inexpensive home-made Single wavelength Ellipsometry with RAE (Rotating Analyser Ellipsometer) configuration has been developed. Spectroscopic ellipsometry (SE) is an optical measurement technique which is based on the measurement of the change of the phase difference (Δ) and the amplitude ratio (ψ) between p and s linear polarized of reflected (or transmitted) light. Our RAE configuration system composed of polarizer, sample, analyzer, detector, and He-Ne laser (λ = 633 nm) that acted as the monochromatic light source. To test the reliability of our SE system, we measure the optical constant of Au bulk and Cr (30 nm thick) film. The optical constant and the thickness were extracted by employing the pseudo-dielectric function and numerical inversion which is based on the secant method, the ψ and Δ of our SE data which is modelled by Fresnel equation. From the extraction using the secant method we obtain the optical constant of the Au bulk sample with n = 0.11 to 0.22 and k = 3.26 to 3.37 which is close to that of using pseudo-dielectric method. We obtain the same result for Cr film with n = 3.66 to 3.81 and k = 5.32 to 5.38 which is close to the result from reference. These results show that our inexpensive home-made Single wavelength Ellipsometry instrument and the extraction method are reliable for determining the optical constant of nanostructured materials.

  2. Growth and Characterization of Tl2S Single Crystals

    Science.gov (United States)

    Gamal, G. A.; Zied, M. Abou; Gerges, M. K.; Galal, E. M.

    2003-09-01

    Single crystals of the Tl2S compound were grown for the first time in our laboratory by a new crystal growth technique based on a modification of the traveling heater method technique (THM). This growth was performed in our laboratory. Electrical conductivity, Hall effect and thermoelectric power (TEP) measurements were carried out in the temperature range (200-575 K). Throughout these measurements, various physical parameters such as effective mass of charge carriers, carrier mobility, diffusion length, diffusion coefficient, and the relaxation time for both majority and minority carriers were found. In conjunction with electrical conductivity and charge carrier concentration, thermoelectric power is discussed.

  3. Synthesis of anisotropic CdS nanostructures via a single-source route

    CSIR Research Space (South Africa)

    Rajasekhar Pullabhotla, VSR

    2011-02-01

    Full Text Available A cadmium tetrahydroisoquinoline dithiocarbamate (DTC) complex has been used as single-source precursor for the synthesis of highly faceted hexadecylamine (HDA) capped CdS nanoparticles. Hexagonal and close to cubic shaped particles with distinct...

  4. Epitaxial growth of unusual 4H hexagonal Ir, Rh, Os, Ru and Cu nanostructures on 4H Au nanoribbons

    KAUST Repository

    Fan, Zhanxi

    2016-09-12

    Metal nanomaterials normally adopt the same crystal structure as their bulk counterparts. Herein, for the first time, the unusual 4H hexagonal Ir, Rh, Os, Ru and Cu nanostructures have been synthesized on 4H Au nanoribbons (NRBs) via solution-phase epitaxial growth under ambient conditions. Interestingly, the 4H Au NRBs undergo partial phase transformation from 4H to face-centered cubic (fcc) structures after the metal coating. As a result, a series of polytypic 4H/fcc bimetallic Au@M (M = Ir, Rh, Os, Ru and Cu) core-shell NRBs has been obtained. We believe that the rational crystal structure-controlled synthesis of metal nanomaterials will bring new opportunities for exploring their phase-dependent physicochemical properties and promising applications.

  5. Iron single crystal growth from a lithium-rich melt

    Science.gov (United States)

    Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

    2018-03-01

    α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

  6. Coexistence and competition of surface diffusion and geometric shielding in the growth of 1D bismuth nanostructures and their ohmic contact

    International Nuclear Information System (INIS)

    Tian, Ye; Jiang, Lianjun; Zhang, Xuejun; Deng, Yangbao; Deng, Shuguang

    2014-01-01

    We study the physical-vapor-deposition of 1D bismuth nanostructures. Bi nanowire elongating along [012] and/or [110] direction as well as anisotropic Bi nano-columns are physical-vapor-deposited successfully. The coexistence and competition of surface diffusion and geometric shielding are critical to their formation as well as growth mode transition among them. Since physical-vapor-deposition is a vacuum process, we make use of it to fabricate the ohmic contact to prevent the damage to the bismuth nanostructures brought by the etching to their thick surface oxide layer. (paper)

  7. Unidirectional seeded single crystal growth from solution of benzophenone

    Science.gov (United States)

    Sankaranarayanan, K.; Ramasamy, P.

    2005-07-01

    A novel crystal growth method has been established for the growth of single crystal with selective orientation at room temperature. Using volatile solvent, the saturated solution containing the material to be crystallized was taken in an ampoule and allowed to crystallize by slow solvent evaporation assisted with a ring heater. The orientation of the growing crystal was imposed by means of a seed fixed at the bottom of the ampoule. By selecting a suitable ring heater voltage and by controlling the ring heater voltage, nucleation and the growth rate of the crystal were controlled more effectively. By employing this novel method, benzophenone single crystal ingots of diameters 10 and 20 mm and length more than 50 mm were successfully grown using xylene as solvent. The ease in scaling up of diameter from 10 to 20 mm shows the vital advantage of this technique. It was possible to achieve solute-crystal conversion efficiency of 100 percent. The grown benzophenone crystal was characterized by FTIR, TG and DTA, powder X-ray diffraction, X-ray rocking curve, optical transmission study and powder SHG measurement. The results show that the crystal quality is at least as good as the quality of the crystal grown by other known methods. Also, microbial growth was naturally avoided in this method, as the fresh solution is constantly made available for the growing crystal.

  8. Detection of a single synthetic antiferromagnetic nanoparticle with an AMR nanostructure: Comparison between simulations and experiments

    DEFF Research Database (Denmark)

    Donolato, M.; Gobbi, M.; Cantoni, M.

    2010-01-01

    magnetoresistance effect and hence an electrical signal. In this paper we use micromagnetic simulations to calculate the output signal of a particularly shaped device in the presence of a single synthetic antiferromagnetic nanoparticle. The calculated magnetoresistive signal is in good agreement with corresponding...

  9. Electrochemistry of single molecules and biomolecules, molecular scale nanostructures, and low-dimensional systems

    DEFF Research Database (Denmark)

    Nazmutdinov, Renat R.; Zinkicheva, Tamara T.; Zinkicheva, Tamara T.

    2018-01-01

    Electrochemistry at ultra-small scales, where even the single molecule or biomolecule can be characterized and manipulated, is on the way to a consolidated status. At the same time molecular electrochemistry is expanding into other areas of sophisticated nano- and molecular scale systems including...

  10. Electrophoretic deposition of ZnO nanostructures: Au nanoclusters on Si substrates induce self-assembled nanowire growth

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, Claudia [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Marin, Oscar [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Real, Silvina [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Comedi, David [CONICET – LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina); Tirado, Mónica, E-mail: mtirado@herrera.unt.edu.ar [Laboratorio de Nanomateriales y Propiedades Dieléctricas, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, San Miguel de Tucumán (Argentina)

    2014-09-15

    Highlights: • ZnO nanowires were grown on silicon substrate by electrophoretic deposition technique without use a porous template. • The growth was induced by Au nanoclusters and was performed at room temperature. • The photoluminescence spectrum for the nanowires obtained shows a broad UV-blue excitonic emission peak and a low emission in the green region. - Abstract: The present work reports the self-assembled growth of ZnO nanowires on silicon substrate with nanometer sized Au clusters using electrophoretic deposition technique at room temperature without a sacrificial template. A colloidal suspension of ≈5 nm sized ZnO nanoparticles dispersed in 2-propanol was used (nanoparticle bandgap of 3.47 eV as determined from absorbance measurements). The results show that the Au nanoclusters on the silicon substrate induce the self-assembly of the ZnO nanoparticles into vertically aligned ZnO nanowires. This effect is tentatively explained as being due to increased electric field intensities near the Au nanoclusters during the electrophoretic deposition. Photoluminescence measurements reveal the presence of quantum confined excitons and a relatively low concentration of deep defects in the nanowires. The electric field guided growth of semiconductor nanostructures at room temperature has great industrial potential as it minimizes production costs and enables the use of substrate materials not withstanding high temperatures.

  11. Growth mechanism, surface and optical properties of ZnO nanostructures deposited on various Au-seeded thickness obtained by mist-atomization

    Energy Technology Data Exchange (ETDEWEB)

    Afaah, A. N., E-mail: afaahabdullah@yahoo.com; Aadila, A., E-mail: aadilaazizali@gmail.com; Asib, N. A. M., E-mail: amierahasib@yahoo.com; Khusaimi, Z., E-mail: zurai142@salam.uitm.edu.my [NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Mohamed, R., E-mail: ruzianamohd@pahang.uitm.edu.my [NANO-Electronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-Electronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    In this paper, growth mechanisms of ZnO nanostructures on non-seeded glass, 6 nm and 12 nm Au seed layer obtained by mist-atomization was proposed. ZnO films were successfully deposited on glass substrate with different thickness of Au seed layer i.e. 6 nm and 12 nm. The surface and optical properties of the prepared samples were investigated using Field emission scanning electron microscopy (FESEM) and photoluminescence (PL). FESEM micrograph show that ZnO nanostructure deposited on 6 nm Au seed layer has uniform formation and well distributed. From PL spectroscopy, the UV emission shows that ZnO deposited on 6 nm Au seed layer has the more intense UV intensity which proved that high crystal quality of nanostructured ZnO deposited on 6 nm Au seed layer.

  12. Controllable growth of nanostructured carbon from coal tar pitch by chemical vapor deposition

    International Nuclear Information System (INIS)

    Liu Xuguang; Yang Yongzhen; Ji Weiyun; Liu Hongyan; Zhang Chunyi; Xu Bingshe

    2007-01-01

    The direct synthesis of vapor grown carbon fibers with different diameters was achieved by the pyrolysis of coal tar pitch by chemical vapor deposition. The products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The experimental results demonstrated that ferrocene content, reaction temperature and Ar flow rate strongly influenced the yield and nature of nanostructured carbon materials, pure carbon microbeads, with diameter distribution ranging from 450 to 650 nm, were also obtained in the absence of catalyst, uniform and straight carbon nanofibers with the outer diameter of about 115 nm were obtained and curl and thick carbon fibers with narrow diameter distribution of 300-350 nm were produced

  13. Electrochemical growth of two-dimensional gold nanostructures on a thin polypyrrole film modified ITO electrode.

    Science.gov (United States)

    Li, Yin; Shi, Gaoquan

    2005-12-22

    Two-dimensional gold nanostructures have been fabricated by electrochemical deposition of gold nanoparticles onto indium tin oxide (ITO) glass substrate modified with thin polypyrrole film. By controlling the electrodeposition conditions, gold nanoparticles with dendritic rod, sheet, flower-like (consisting of staggered nanosheets), and pinecone-like structures were generated. The flower-like gold nanoparticles showed high catalytic activity on electrochemical reduction of oxygen, and its activity was measured to be approximately 25 times that of gold pinecones and 10(4) times that of gold nanosheets in terms of gold weight. The pinecone-like nanoparticles can form a compact film with nano-/microscale binary structure like a lotus leaf surface. After modification with n-dodecanethiol, the surface showed superhydrophobic properties with a water contact angle of 153.4 degrees and a tilt angle of 4.4 degrees (5 microL droplet).

  14. Synthesis of single crystal manganese oxide octahedral molecular sieve (OMS) nanostructures with tunable tunnels and shapes.

    Science.gov (United States)

    Li, Wei-Na; Yuan, Jikang; Gomez-Mower, Sinue; Sithambaram, Shantakumar; Suib, Steven L

    2006-02-23

    A new and facile route is reported to manipulate the self-assembly synthesis of hierarchically ordered Rb-OMS-2 and pyrolusite with an interesting flowerlike morphology by a direct and mild reaction between rubidium chromateand manganese sulfate without any organic templates. The crystal forms, morphologies, and tunnel sizes of the obtained OMS materials can be controlled. A mechanism for the growth of manganese dioxides with flowerlike architectures was proposed. The obtained products exhibit potential for use in catalysis and other applications.

  15. The Nanostructure Formation and Growth Evolution of Ferroelectric/Ferromagnetic BiFeO3-CoFe2O4 Thin Films

    Science.gov (United States)

    Young, Sheng Yu; Salamanca-Riba, Lourdes G.; Zheng, Haimei

    2006-03-01

    We have investigated the mechanism of the self-assembly of BiFeO3-CoFe2O4 (BFO-CFO) ferroelectric/ferromagnetic thin film nanostructures using high-resolution transmission electron microscopy. We discuss the formation of the CFO columnar structure during the deposition process. The BFO-CFO thin films were deposited on SrTiO3 (001) single crystal substrates using pulsed laser deposition at a substrate temperature of 700 ^oC and deposition rate of around 5nm/min. In the early stages of growth, CFO domains form with dome like island shape and are covered by a BFO layer. After approximately 10 mins of continuous deposition, the nanocomposite rearranges and diffusion dominates to form a self-assembly of faceted CFO columns that extend to the surface of the film. These columns show pyramidal-like faceted shape and are embedded in the BFO matrix. A few atomic layers of BFO lie at the interface between the CFO columnar structures and the substrate. This layer helps relax the misfit strain between CFO and STO. The magnetic properties of the nanocomposite samples will also be presented.

  16. Mutiple Czochralski growth of silicon crystals from a single crucible

    Science.gov (United States)

    Lane, R. L.; Kachare, A. H.

    1980-01-01

    An apparatus for the Czochralski growth of silicon crystals is presented which is capable of producing multiple ingots from a single crucible. The growth chamber features a refillable crucible with a water-cooled, vacuum-tight isolation valve located between the pull chamber and the growth furnace tank which allows the melt crucible to always be at vacuum or low argon pressure when retrieving crystal or introducing recharge polysilicon feed stock. The grower can thus be recharged to obtain 100 kg of silicon crystal ingots from one crucible, and may accommodate crucibles up to 35 cm in diameter. Evaluation of the impurity contents and I-V characteristics of solar cells fabricated from seven ingots grown from two crucibles reveals a small but consistent decrease in cell efficiency from 10.4% to 9.6% from the first to the fourth ingot made in a single run, which is explained by impurity build-up in the residual melt. The crystal grower thus may offer economic benefits through the extension of crucible lifetime and the reduction of furnace downtime.

  17. A single-stranded architecture for cotranscriptional folding of RNA nanostructures

    DEFF Research Database (Denmark)

    Geary, Cody; Rothemund, Paul; Andersen, Ebbe Sloth

    2014-01-01

    . We introduce an architecture for designing artificial RNA structures that fold from a single strand, in which arrays of antiparallel RNA helices are precisely organized by RNA tertiary motifs and a new type of crossover pattern. We constructed RNA tiles that assemble into hexagonal lattices......Artificial DNA and RNA structures have been used as scaffolds for a variety of nanoscale devices. In comparison to DNA structures, RNA structures have been limited in size, but they also have advantages: RNA can fold during transcription and thus can be genetically encoded and expressed in cells...

  18. Emerging fabrication techniques for 3D nano-structuring in plasmonics and single molecule studies

    Science.gov (United States)

    de Angelis, F.; Liberale, C.; Coluccio, M. L.; Cojoc, G.; di Fabrizio, E.

    2011-07-01

    The application of new methods and techniques to fields such as biology and medicine is becoming more and more demanding since the request of detailed information down to single molecules is a scientific necessity and a technical realistic possibility. In this effort a key role is played by emerging fabrication techniques. One of the hardest challenges is to incorporate the third dimension in the design and fabrication of novel devices. Significantly, this means that conventional nano-fabrication methods, intrinsically useful for planar structuring, have to be substituted or complemented with new approaches. In this paper we show how emerging techniques can be used for 3D structuring of noble metals down to nanoscale. In particular, the paper deals with electroless deposition of silver, ion and electron beam induced deposition, focused ion beam milling, and two-photon lithography. We exploited these techniques to fabricate different plasmonics nanolenses, nanoprobes and novel beads for optical tweezers. In the future these devices will be used for the manipulation and chemical investigation of single cells with sensitivity down to a few molecules in label free conditions and native environment. Although this paper is only devoted to nanofabrication, we foresee that the fields of biology and medicine will directly gain substantial advantages from this approach.

  19. Growth and characterisation of lead iodide single crystals

    International Nuclear Information System (INIS)

    Tonn, Justus

    2012-01-01

    The work in hand deals with the growth and characterisation of lead iodide (PbI 2 ) single crystals. PbI 2 is regarded as a promising candidate for low-noise X- and gamma ray detection at room temperature. Its benefits if compared to conventional materials like HgI 2 , CdTe, Si, or GaAs lie in a band gap energy of 2.32 eV, an excellent ability to absorb radiation, and a high electrical resistivity. For an application of PbI 2 as detector material the growth and characterisation of crystals with high chemical and structural quality is extremely challenging. In light of this, the effectiveness of zone purification of the PbI 2 used for crystal growth was confirmed by spectroscopic analysis. Furthermore, technological aspects during processing of purified PbI 2 were investigated. With the help of thermal analysis, a correlation was found between the degree of exposing the source material to oxygen from the air and the structural quality of the resulting crystals. A hydrogen treatment was applied to PbI 2 as an effective method for the removal of oxidic pollutions, which resulted in a significant reduction of structural defects like polytypic growth and stress-induced cracking. The growth of PbI 2 single crystals was, among others, carried out by the Bridgman-Stockbarger method. In this context, much effort was put on the investigation of influences resulting from the design and preparation of ampoules. For the first time, crystal growth of PbI 2 was also carried out by the Czochralski method. If compared to the Bridgman-Stockbarger method, the Czochralski technique allowed a significantly faster growth of nearly crack-free crystals with a reproducible predetermination of crystallographic orientation. By an optimised sample preparation of PbI 2 , surface orientations perpendicular to the usually cleaved (0001) plane were realised. It is now possible to determine the material properties along directions which were so far not accessible. Thus, for example, the ratio of

  20. Studies on the controlled growth of InAs nanostructures on scission surfaces; Untersuchungen zum kontrollierten Wachstum von InAs-Nanostrukturen auf Spaltflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, J.

    2006-01-15

    The aim of this thesis was the controlled alignment of self-assembled InAs nano-structures on a {l_brace}110{r_brace}-oriented surface. The surface is prestructured with the atomic precision offered by molecular beam epitaxy, using the cleaved edge overgrowth-technique. On all samples grown within this work, the epitaxial template in the first growth step was deposited on a (001)GaAs substrate, while the InAs-layer forming the nanostructures during the second growth step was grown on cleaved {l_brace}110{r_brace}-GaAs surfaces. Atomic Force Microscopy (AFM) investigations demonstrate the formation of quantum dot (QD)-like nanostructures on top of the AlAs-stripes. X-ray diffraction measurements on large arrays of aligned quantum dots demonstrate that the quantum dots are formed of pure InAs. First investigations on the optical properties of these nanostructures were done using microphotoluminescence-spectroscopy with both high spatial and spectral resolution. (orig.)

  1. High throughput nanostructure-initiator mass spectrometry screening of microbial growth conditions for maximal β-glucosidase production

    Directory of Open Access Journals (Sweden)

    Xiaoliang eCheng

    2013-12-01

    Full Text Available Production of biofuels via enzymatic hydrolysis of complex plant polysaccharides is a subject of intense global interest. Microbial communities are known to express a wide range of enzymes necessary for the saccharification of lignocellulosic feedstocks and serve as a powerful reservoir for enzyme discovery. However, the growth temperature and conditions that yield high cellulase activity vary widely, and the throughput to identify optimal conditions has been limited by the slow handling and conventional analysis. A rapid method that uses small volumes of isolate culture to resolve specific enzyme activity is needed. In this work, a high throughput nanostructure-initiator mass spectrometry (NIMS based approach was developed for screening a thermophilic cellulolytic actinomycete, Thermobispora bispora, for β-glucosidase production under various growth conditions. Media that produced high β-glucosidase activity were found to be I/S + glucose or microcrystalline cellulose (MCC, Medium 84 + rolled oats, and M9TE + MCC at 45 °C. Supernatants of cell cultures grown in M9TE + 1% MCC cleaved 2.5 times more substrate at 45 °C than at all other temperatures. While T. bispora is reported to grow optimally at 60 °C in Medium 84 + rolled oats and M9TE + 1% MCC, approximately 40% more conversion was observed at 45 °C. This high throughput NIMS approach may provide an important tool in discovery and characterization of enzymes from environmental microbes for industrial and biofuel applications.

  2. Influence of the pre-adsorption of group III metals on the growth of Ge nanostructures on vicinal Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Speckmann, Moritz; Schmidt, Thomas; Flege, Jan Ingo; Heidmann, Inga; Hoecker, Jan; Wilkens, Torsten; Falta, Jens [Institute of Solid State Physics, University of Bremen (Germany)

    2010-07-01

    The employment of metals as surfactants (surface active agents) is a promising approach to influence the growth of Ge nanostructures on Si surfaces. Especially for group III and group V elements an enhanced or suppressed Stranski-Krastanov growth behaviour is found, respectively. For all group III metal on silicon systems presented in this study we observe a drastic change of the surface morphology after adsorption of a few monolayers. For the investigations we used a variety of surface sensitive techniques, e.g., scanning tunneling microscopy (STM), spot profile analysing low-energy electron diffraction (SPA-LEED), low-energy electron microscopy (LEEM), and X-ray standing waves (XSW). On the one hand, the adsorption of Ga and In leads to a smoothening of the intrinsically unstable Si(112) surface and the development of 1D metal chains. But on the other hand, the stable Si(113) is decomposed into a regular array of nanofacets after adsorption of Ga. For all cases shown here the possibility of growing highly anisotropic Ge Islands is demonstrated (Ga/Si(113),Ga/Si(112),In/Si(112)).

  3. Ultrafast modification of the spontaneous decay rate by plasmonic nanostructures: a step toward manipulation of a single atom

    International Nuclear Information System (INIS)

    Zavareian, N

    2014-01-01

    A controllable method for modifying spontaneous emission of an electric dipole located in close proximity to a plasmonic nanostructure is proposed. The nanostructure constructed of two triangular nanowires, in the form of a dimer, on a substrate in which the gallium film on the micrometer scale is the main layer. The results illustrate that phase transition of the gallium film from the α-crystalline to liquid phase leads to variation of the spectrum of radiative and nonradiative decay rates of the dipole where such a transition depends on parameters of the dipole, e.g. position, orientation and emission wavelength as well as on the nanostructure, e.g. shape and size of the dimer and also properties of the substrate. On the other hand, it is found that during phase transition modification of nanostructure resonances is negligible while the radiative decay rate changes. (letter)

  4. Growth and evaluation of lanthanoids orthoniobates single crystals processed by a miniature pedestal growth technique

    International Nuclear Information System (INIS)

    Octaviano, E.S.; Reyes Ardila, D.; Andrade, L.H.C.; Siu Li, M.; Andreeta, J.P.

    2004-01-01

    Optimized conditions for the growth of lanthanoids orthoniobates (LnNbO 4 , Ln=lanthanide elements) single crystal minirods by a floating zone technique were investigated. Adequate atmospheres and pulling to feeding speed ratios to grow these materials were determined. Emphasis is given to the study of LaNbO 4 because of their more favorable growth conditions and crystalline quality. This material can be efficiently doped with rare earth elements such as erbium. It grows with high crystallinity and its preferential growth direction is [110]. A preliminary evaluation of optical properties of Er 3+ -doped LaNbO 4 single crystal under the Judd-Ofelt formalism indicates spectral parameters Ω t close and even larger than for Er 3+ ions in YVO 4 . (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. A single phosphorus treatment doubles growth of cyanobacterial lichen transplants.

    Science.gov (United States)

    McCune, Bruce; Caldwell, Bruce A

    2009-02-01

    Lichens are reputedly slow growing and become unhealthy or die in response to supplements of the usual limiting resources, such as water and nitrogen. We found, however, that the tripartite cyanobacterial lichen Lobaria pulmonaria doubled in annual biomass growth after a single 20-minute immersion in a phosphorus solution (K2HPO4), as compared to controls receiving no supplemental phosphorus. This stimulation of cyanolichens by phosphorus has direct relevance to community and population ecology of lichens, including improving models of lichen performance in relation to air quality, improving forest management practices affecting old-growth associated cyanolichens, and understanding the distribution and abundance of cyanolichens on the landscape. Phosphorus may be as important a stimulant to cyanobacterial-rich lichen communities as it is to cyanobacteria in aquatic ecosystems.

  6. Seed-mediated electrochemical growth of gold nanostructures on indium tin oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Praig, Vera G.; Szunerits, Sabine [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces (LEPMI), CNRS-INPG-UJF, 1130 rue de la piscine, BP 75, 38402 St. Martin d' Heres Cedex (France); Institut de Recherche Interdisciplinaire (IRI), USR CNRS 3078 and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN),UMR CNRS-8520, Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Piret, Gaelle; Boukherroub, Rabah [Institut de Recherche Interdisciplinaire (IRI), USR CNRS 3078 and Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN),UMR CNRS-8520, Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Manesse, Mael [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces (LEPMI), CNRS-INPG-UJF, 1130 rue de la piscine, BP 75, 38402 St. Martin d' Heres Cedex (France); Castel, Xavier [Institut d' Electronique et de Telecommunications de Rennes (IETR), UMR CNRS 6164, 18 rue H. Wallon, BP 406, 22004 Saint-Brieuc Cedex 1 (France)

    2008-11-15

    Two-dimensional gold nanostructures (Au NSs) were fabricated on amine-terminated indium tin oxide (ITO) thin films using constant potential electrolysis. By controlling the deposition time and by choosing the appropriate ITO surface, Au NSs with different shapes were generated. When Au NSs were formed directly on aminosilane-modified ITO, the surface roughness of the interface was largely enhanced. Modification of such Au NSs with n-tetradecanethiol resulted in a highly hydrophobic interface with a water contact angle of 144 . Aminosilane-modified ITO films further modified with colloidal Au seeds before electrochemical Au NSs formation demonstrated interesting optical properties. Depending on the deposition time, surface colors ranging from pale pink to beatgold-like were observed. The optical properties and the chemical stability of the interfaces were characterized using UV-vis absorption spectroscopy. Well-defined localized surface plasmon resonance signals were recorded on Au-seeded interfaces with {lambda}{sub max}=675{+-} 2 nm (deposition time 180 s). The prepared interfaces exhibited long-term stability in various solvents and responded linearly to changes in the corresponding refractive indices. (author)

  7. Seed-mediated electrochemical growth of gold nanostructures on indium tin oxide thin films

    International Nuclear Information System (INIS)

    Praig, Vera G.; Piret, Gaelle; Manesse, Mael; Castel, Xavier; Boukherroub, Rabah; Szunerits, Sabine

    2008-01-01

    Two-dimensional gold nanostructures (Au NSs) were fabricated on amine-terminated indium tin oxide (ITO) thin films using constant potential electrolysis. By controlling the deposition time and by choosing the appropriate ITO surface, Au NSs with different shapes were generated. When Au NSs were formed directly on aminosilane-modified ITO, the surface roughness of the interface was largely enhanced. Modification of such Au NSs with n-tetradecanethiol resulted in a highly hydrophobic interface with a water contact angle of 144 deg. Aminosilane-modified ITO films further modified with colloidal Au seeds before electrochemical Au NSs formation demonstrated interesting optical properties. Depending on the deposition time, surface colors ranging from pale pink to beatgold-like were observed. The optical properties and the chemical stability of the interfaces were characterized using UV-vis absorption spectroscopy. Well-defined localized surface plasmon resonance signals were recorded on Au-seeded interfaces with λ max = 675 ± 2 nm (deposition time 180 s). The prepared interfaces exhibited long-term stability in various solvents and responded linearly to changes in the corresponding refractive indices

  8. Distance dependence of the energy transfer rate from a single semiconductor nanostructure to graphene.

    Science.gov (United States)

    Federspiel, François; Froehlicher, Guillaume; Nasilowski, Michel; Pedetti, Silvia; Mahmood, Ather; Doudin, Bernard; Park, Serin; Lee, Jeong-O; Halley, David; Dubertret, Benoît; Gilliot, Pierre; Berciaud, Stéphane

    2015-02-11

    The near-field Coulomb interaction between a nanoemitter and a graphene monolayer results in strong Förster-type resonant energy transfer and subsequent fluorescence quenching. Here, we investigate the distance dependence of the energy transfer rate from individual, (i) zero-dimensional CdSe/CdS nanocrystals and (ii) two-dimensional CdSe/CdS/ZnS nanoplatelets to a graphene monolayer. For increasing distances d, the energy transfer rate from individual nanocrystals to graphene decays as 1/d(4). In contrast, the distance dependence of the energy transfer rate from a two-dimensional nanoplatelet to graphene deviates from a simple power law but is well described by a theoretical model, which considers a thermal distribution of free excitons in a two-dimensional quantum well. Our results show that accurate distance measurements can be performed at the single particle level using graphene-based molecular rulers and that energy transfer allows probing dimensionality effects at the nanoscale.

  9. Modeling bacterial population growth from stochastic single-cell dynamics.

    Science.gov (United States)

    Alonso, Antonio A; Molina, Ignacio; Theodoropoulos, Constantinos

    2014-09-01

    A few bacterial cells may be sufficient to produce a food-borne illness outbreak, provided that they are capable of adapting and proliferating on a food matrix. This is why any quantitative health risk assessment policy must incorporate methods to accurately predict the growth of bacterial populations from a small number of pathogens. In this aim, mathematical models have become a powerful tool. Unfortunately, at low cell concentrations, standard deterministic models fail to predict the fate of the population, essentially because the heterogeneity between individuals becomes relevant. In this work, a stochastic differential equation (SDE) model is proposed to describe variability within single-cell growth and division and to simulate population growth from a given initial number of individuals. We provide evidence of the model ability to explain the observed distributions of times to division, including the lag time produced by the adaptation to the environment, by comparing model predictions with experiments from the literature for Escherichia coli, Listeria innocua, and Salmonella enterica. The model is shown to accurately predict experimental growth population dynamics for both small and large microbial populations. The use of stochastic models for the estimation of parameters to successfully fit experimental data is a particularly challenging problem. For instance, if Monte Carlo methods are employed to model the required distributions of times to division, the parameter estimation problem can become numerically intractable. We overcame this limitation by converting the stochastic description to a partial differential equation (backward Kolmogorov) instead, which relates to the distribution of division times. Contrary to previous stochastic formulations based on random parameters, the present model is capable of explaining the variability observed in populations that result from the growth of a small number of initial cells as well as the lack of it compared to

  10. Acquisition of Single Crystal Growth and Characterization Equipment. Final report

    International Nuclear Information System (INIS)

    Maple, M. Brian; Zocco, Diego A.

    2008-01-01

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and scattering

  11. Acquisition of Single Crystal Growth and Characterization Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Maple, M. Brian; Zocco, Diego A.

    2008-12-09

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and

  12. Facile Synthesis and Tensile Behavior of TiO2 One-Dimensional Nanostructures

    Directory of Open Access Journals (Sweden)

    Li Shu-you

    2009-01-01

    Full Text Available Abstract High-yield synthesis of TiO2 one-dimensional (1D nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO2 with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.

  13. Self-assembly growth and structure study of BiFeO3-CoFe2O4 nanostructure film

    Science.gov (United States)

    Song, Q.; Zhang, X. Y.; Ong, C. K.

    2010-01-01

    Pulsed laser deposition method was used to prepare (0.67) BiFeO3- (0.33) CoFe2O4 nanostructure thin film. The XRD analysis shows that lower growth temperature will not obtain separation of BiFeO3 and CoFe2O4 phase. Post-annealing treatment will induce the phase separation. XRD data and SEM image both confirm these phase separation.

  14. Single crystalline metal films as substrates for graphene growth

    Energy Technology Data Exchange (ETDEWEB)

    Zeller, Patrick; Henss, Ann-Kathrin; Wintterlin, Joost [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany); Weinl, Michael; Schreck, Matthias [Institut fuer Physik, Universitaet Augsburg (Germany); Speck, Florian; Ostler, Markus [Lehrstuhl fuer Technische Physik, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Institut fuer Physik, Technische Universitaet Chemnitz (Germany); Seyller, Thomas [Institut fuer Physik, Technische Universitaet Chemnitz (Germany)

    2017-11-15

    Single crystalline metal films deposited on YSZ-buffered Si(111) wafers were investigated with respect to their suitability as substrates for epitaxial graphene. Graphene was grown by CVD of ethylene on Ru(0001), Ir(111), and Ni(111) films in UHV. For analysis a variety of surface science methods were used. By an initial annealing step the surface quality of the films was strongly improved. The temperature treatments of the metal films caused a pattern of slip lines, formed by thermal stress in the films, which, however, did not affect the graphene quality and even prevented wrinkle formation. Graphene was successfully grown on all three types of metal films in a quality comparable to graphene grown on bulk single crystals of the same metals. In the case of the Ni(111) films the originally obtained domain structure of rotational graphene phases could be transformed into a single domain by annealing. This healing process is based on the control of the equilibrium between graphene and dissolved carbon in the film. For the system graphene/Ni(111) the metal, after graphene growth, could be removed from underneath the epitaxial graphene layer by a pure gas phase reaction, using the reaction of CO with Ni to give gaseous Ni(CO){sub 4}. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-04-01

    crystals will be discussed in Chapter 3 and 4. Despite their outstanding charge transport characteristics, organolead halide perovskite single crystals grown by hitherto reported crystallization methods are not suitable for most optoelectronic devices due to their small aspect ratios and free standing growth. As the other major part of work of this dissertation, explorative work on growing organolead halide perovskite monocrystalline films and further their application in solar cells will be discussed in Chapter 5.

  16. Growth of MoO3 nanostructured thin films as a function of O2-partial pressure

    Science.gov (United States)

    Sharma, Rabindar Kumar; Kumar, Prabhat; Reddy, G. B.

    2015-06-01

    In this report, we synthesized molybdenum trioxide (α-MoO3) nanostructured thin films (NSTs) with nanoflakes (NFs) on the Ni-coated glass substrates employing plasma assisted sublimation process (PASP) as a function of oxygen partial pressure (PO2). The effect of oxygen partial pressure on structural, morphological, and vibrational properties have been investigated systematically. The structural analysis divulged that all films deposited at different PO2 have pure orthorhombic phase, no impurity phase is detected under the limit of resolution. The morphological studies of samples is carried out by SEM, revealed that features as well as alignment of MoO3 NSTs can be monitored by PO2 and the sample having best features is obtained at 7.5×10-2 Torr. In addition, the more insight information is accomplished by TEM/HRTEM on the best featured sample, which confirmed the single crystalline nature of nanoflakes. The vibrational study of all samples are performed by FTIR, and strongly supports the XRD observations. All the results are in consonance with each other.

  17. Growth of single-crystal YAG fiber optics.

    Science.gov (United States)

    Nie, Craig D; Bera, Subhabrata; Harrington, James A

    2016-07-11

    Single-crystal YAG (Y3Al5O12) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

  18. Growth of Ti or Fe doped lithium niobate single crystals

    International Nuclear Information System (INIS)

    Lee, J.H.; Kim, J.N.; Ro, J.H.; Kim, J.W.; Jeen, G.S.; Kim, Y.C.; Lee, H.S.

    1982-01-01

    This paper reprots a study of the growth of Ti or Fe doped LiNbO 3 single crystals by Czochralski method and its physical properties. On the basis of this study we have developed a growth procedure that produces a high yield of twin-free boules. The quality is better for crystals that are lightly doped with Ti than for those of high concentrations. However there are no significant quality differences among the crystals with concentrations of less than 0.5wt% of Fe. The crystals are characterized by optical absorption and magnetic susceptibility. Undoped crystals show the magnetic susceptibility of -10x10 -6 cgs, which is diamagnetic. The crystals with 0.01wt% and 0.5wt% of ferromagnetic susceptibilities of 2.6x1a -6 cgs, and 80x10 -6 cgs, respectively. Therefore, Fe-doped crystals are paramagnetic. Very small changes of magnetic susceptibilities have been observed in the Ti-doped crystals. (Author)

  19. Single-crystal metal growth on amorphous insulating substrates.

    Science.gov (United States)

    Zhang, Kai; Pitner, Xue Bai; Yang, Rui; Nix, William D; Plummer, James D; Fan, Jonathan A

    2018-01-23

    Metal structures on insulators are essential components in advanced electronic and nanooptical systems. Their electronic and optical properties are closely tied to their crystal quality, due to the strong dependence of carrier transport and band structure on defects and grain boundaries. Here we report a method for creating patterned single-crystal metal microstructures on amorphous insulating substrates, using liquid phase epitaxy. In this process, the patterned metal microstructures are encapsulated in an insulating crucible, together with a small seed of a differing material. The system is heated to temperatures above the metal melting point, followed by cooling and metal crystallization. During the heating process, the metal and seed form a high-melting-point solid solution, which directs liquid epitaxial metal growth. High yield of single-crystal metal with different sizes is confirmed with electron backscatter diffraction images, after removing the insulating crucible. Unexpectedly, the metal microstructures crystallize with the [Formula: see text] direction normal to the plane of the film. This platform technology will enable the large-scale integration of high-performance plasmonic and electronic nanosystems.

  20. Hydrothermal synthesis of nanostructured SnO particles through crystal growth in the presence of gelatin

    Science.gov (United States)

    Uchiyama, Hiroaki; Nakanishi, Shunsuke; Kozuka, Hiromitsu

    2014-09-01

    Crystalline SnO particles were obtained from Sn6O4(OH)4 by the hydrothermal treatment in aqueous solutions containing gelatin at 150 °C for 24 h, where the morphologies of the SnO products changed from blocks to layered disks, stacked plates and unshaped aggregates with increasing amount of gelatin in the solutions. Such morphological changes of SnO particles were thought to be attributed to the suppression of the growth of SnO crystals by the adsorbed gelatin.

  1. Single-step direct fabrication of pillar-on-pore hybrid nanostructures in anodizing aluminum for superior superhydrophobic efficiency.

    Science.gov (United States)

    Jeong, Chanyoung; Choi, Chang-Hwan

    2012-02-01

    Conventional electrochemical anodizing processes of metals such as aluminum typically produce planar and homogeneous nanopore structures. If hydrophobically treated, such 2D planar and interconnected pore structures typically result in lower contact angle and larger contact angle hysteresis than 3D disconnected pillar structures and, hence, exhibit inferior superhydrophobic efficiency. In this study, we demonstrate for the first time that the anodizing parameters can be engineered to design novel pillar-on-pore (POP) hybrid nanostructures directly in a simple one-step fabrication process so that superior surface superhydrophobicity can also be realized effectively from the electrochemical anodization process. On the basis of the characteristic of forming a self-ordered porous morphology in a hexagonal array, the modulation of anodizing voltage and duration enabled the formulation of the hybrid-type nanostructures having controlled pillar morphology on top of a porous layer in both mild and hard anodization modes. The hybrid nanostructures of the anodized metal oxide layer initially enhanced the surface hydrophilicity significantly (i.e., superhydrophilic). However, after a hydrophobic monolayer coating, such hybrid nanostructures then showed superior superhydrophobic nonwetting properties not attainable by the plain nanoporous surfaces produced by conventional anodization conditions. The well-regulated anodization process suggests that electrochemical anodizing can expand its usefulness and efficacy to render various metallic substrates with great superhydrophilicity or -hydrophobicity by directly realizing pillar-like structures on top of a self-ordered nanoporous array through a simple one-step fabrication procedure.

  2. Catalytic growth of ZnO nanostructures by r.f. magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Arroyo-Hernández María

    2011-01-01

    Full Text Available Abstract The catalytic effect of gold seed particles deposited on a substrate prior to zinc oxide (ZnO thin film growth by magnetron sputtering was investigated. For this purpose, selected ultra thin gold layers, with thicknesses close to the percolation threshold, are deposited by thermal evaporation in ultra high vacuum (UHV conditions and subsequently annealed to form gold nanodroplets. The ZnO structures are subsequently deposited by r.f. magnetron sputtering in a UHV chamber, and possible morphological differences between the ZnO grown on top of the substrate and on the gold are investigated. The results indicate a moderate catalytic effect for a deposited gold underlayer of 4 nm, quite close to the gold thin film percolation thickness.

  3. The growth of nanostructured Cu{sub 2}ZnSnS{sub 4} films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Che Sulaiman, Nurul Suhada; Nee, Chen Hon [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Lee, Yen Sian [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    Highlights: • Nanostructured CZTS films were grown at room temperature by using 355 nm laser. • CZTS films with E{sub g} of 1.9 eV have been obtained at 2 J cm{sup −2} at room temperature. • At high fluence, Cu/Sn rich droplets affected the overall quality of the films. • Improved crystallinity and E{sub g} of 1.5 eV was obtained at substrate temperature as low as 100 °C. - Abstract: In this work, we investigated on the growth of Cu{sub 2}ZnSnS{sub 4} films by using pulsed Nd:YAG laser (355 nm) ablation of a quaternary Cu{sub 2}ZnSnS{sub 4} target. Depositions were performed at laser fluence from 0.5 to 4 J cm{sup −2}. The films were grown at substrate temperature from 27 °C to 300 °C onto glass and silicon substrates. The dependence of the film morphology, composition, and optical properties are studied and discussed with respect to laser fluence and substrate temperature. Composition analysis from energy dispersive X-ray spectral results show that CZTS films with composition near stoichiometric were obtained at an optimized fluence at 2 J cm{sup −2} by 355 nm laser where the absorption coefficient is >10{sup 4} cm{sup −1}, and optical band gap from a Tauc plot was ∼1.9 eV. At high fluence, Cu and Sn rich droplets were detected which affect the overall quality of the films. The presence of the droplets was associated to the high degree of preferential and subsurface melting on the target during high fluence laser ablation. Crystallinity and optical band gap (1.5 eV) were improved when deposition was performed at substrate temperature of 100 °C.

  4. Nanostructured Graphene-Titanium Dioxide Composites Synthesized by a Single-Step Aerosol Process for Photoreduction of Carbon Dioxide.

    Science.gov (United States)

    Wang, Wei-Ning; Jiang, Yi; Fortner, John D; Biswas, Pratim

    2014-07-01

    Photocatalytic reduction of carbon dioxide (CO 2 ) to hydrocarbons by using nanostructured materials activated by solar energy is a promising approach to recycling CO 2 as a fuel feedstock. CO 2 photoreduction, however, suffers from low efficiency mainly due to the inherent drawback of fast electron-hole recombination in photocatalysts. This work reports the synthesis of nanostructured composites of titania (TiO 2 ) nanoparticles (NPs) encapsulated by reduced graphene oxide (rGO) nanosheets via an aerosol approach. The role of synthesis temperature and TiO 2 /GO ratio in CO 2 photoreduction was investigated. As-prepared nanocomposites demonstrated enhanced CO 2 conversion performance as compared with that of pristine TiO 2 NPs due to the strong electron trapping capability of the rGO nanosheets.

  5. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    International Nuclear Information System (INIS)

    Koparanova, N.; Simov, S.

    1985-01-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more. (author)

  6. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    Energy Technology Data Exchange (ETDEWEB)

    Koparanova, N.; Simov, S. (Bylgarska Akademiya na Naukite, Sofia. Inst. po Fizika na Tvyrdoto Tyalo); Genchev, D. (Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Metchenov, G. (Research Inst. of Criminalistics and Criminology, Sofia (Bulgaria))

    1985-02-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more.

  7. Enhanced Ethanol Gas Sensing Properties of SnO2-Core/ZnO-Shell Nanostructures

    Directory of Open Access Journals (Sweden)

    T. Tharsika

    2014-08-01

    Full Text Available An inexpensive single-step carbon-assisted thermal evaporation method for the growth of SnO2-core/ZnO-shell nanostructures is described, and the ethanol sensing properties are presented. The structure and phases of the grown nanostructures are investigated by field-emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM and X-ray diffraction (XRD techniques. XRD analysis indicates that the core-shell nanostructures have good crystallinity. At a lower growth duration of 15 min, only SnO2 nanowires with a rectangular cross-section are observed, while the ZnO shell is observed when the growth time is increased to 30 min. Core-shell hierarchical nanostructures are present for a growth time exceeding 60 min. The growth mechanism for SnO2-core/ZnO-shell nanowires and hierarchical nanostructures are also discussed. The sensitivity of the synthesized SnO2-core/ZnO-shell nanostructures towards ethanol sensing is investigated. Results show that the SnO2-core/ZnO-shell nanostructures deposited at 90 min exhibit enhanced sensitivity to ethanol. The sensitivity of SnO2-core/ZnO-shell nanostructures towards 20 ppm ethanol gas at 400 °C is about ~5-times that of SnO2 nanowires. This improvement in ethanol gas response is attributed to high active sensing sites and the synergistic effect of the encapsulation of SnO2 by ZnO nanostructures.

  8. Ultrasonic spray pyrolysis growth of ZnO and ZnO:Al nanostructured films: Application to photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Kenanakis, G., E-mail: gkenanak@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology – Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Katsarakis, N. [Institute of Electronic Structure and Laser, Foundation for Research and Technology – Hellas, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece)

    2014-12-15

    Highlights: • Al–ZnO thin films and nanostructures were obtained by ultrasonic spray pyrolysis. • The texture and morphology of the samples depend on the deposition parameters. • The photocatalytic degradation of stearic acid was studied upon UV-A irradiation. - Abstract: Pure and Al-doped ZnO (Al = 1, 3, 5%) nanostructured thin films were grown at 400 °C on glass substrates by ultrasonic spray pyrolysis, a simple, environmental-friendly and inexpensive method, using aqueous solutions as precursors. The structural and morphological characteristics of the samples depend drastically on deposition parameters; ZnO nanostructured films, nanopetals and nanorods were systematically obtained by simply varying the precursor solution and/or the spraying time. Transmittance measurements have shown that all samples are transparent in the visible wavelength region. Finally, the photocatalytic properties of the samples were investigated against the degradation of stearic acid under UV-A light illumination (365 nm); both pure and Al-doped ZnO nanostructured thin films show good photocatalytic activity regarding the degradation of stearic acid, due to their good crystallinity and large surface area.

  9. Superhydrophilic nanostructure

    Science.gov (United States)

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  10. Ultratough CVD single crystal diamond and three dimensional growth thereof

    Science.gov (United States)

    Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

    2009-09-29

    The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

  11. Growth of 2-amino-5-chlorobenzophenone single crystal by ...

    Indian Academy of Sciences (India)

    Abstract. Organic single crystals of 2-amino-5-chlorobenzophenone (2A5CB) were grown by Microtube Czochral- ski method using Microtube as a seed. The grown crystals were characterized by single crystal and powder X-ray diffraction. The functional groups of the grown crystal were found using Fourier transform ...

  12. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    Administrator

    Organic compound; growth from solution; characterization; nonlinear optical materials. 1. Introduction. Organic nonlinear optical (NLO) materials have attracted much attention due to their potential applications in telecommunication, optical switching, optical frequency conversion, THz generation, electro-optical and inte-.

  13. Growth and characterization of propyl-para-hydroxybenzoate single ...

    Indian Academy of Sciences (India)

    Author Affiliations. N Karunagaran1 P Ramasamy1 R Perumal Ramasamy2. Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110, India; Department of Physics, Anna University, Chennai 600 025, India ...

  14. Single-crystal growth of ceria-based materials

    International Nuclear Information System (INIS)

    Ulbrich, Gregor

    2015-01-01

    In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

  15. Nanostructured superconductors

    National Research Council Canada - National Science Library

    Moshchalkov, V. V; Fritzsche, Joachim

    2011-01-01

    ... through nanostructuring and for developing a variety of novel fluxonics devices based on vortex manipulation. Nanostructuring can, in fact, create such conditions for the flux pinning by arrays of nanofabricated antidots or magnetic dots, which could maximize the second important superconducting critical parameter (critical current) up to its theoretical limit ...

  16. Evolution of Zinc Oxide Nanostructures Grown on Graphene by Ultrasonic Spray Pyrolysis and Its Statistical Growth Modelling

    Science.gov (United States)

    Ali, Amgad Ahmed; Hashim, Abdul Manaf

    2015-11-01

    The evolution of zinc oxide nanostructures grown on graphene by alcohol-assisted ultrasonic spray pyrolysis was investigated. The evolution of structures is strongly depended on pyrolysis parameters, i.e., precursor molarity, precursor flow rate, precursor injection/deposition time, and substrate temperature. Field-effect scanning electron microscope analysis, energy dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy were used to investigate the properties of the synthesized nanostructures and to provide evidence for the structural changes according to the changes in the pyrolysis parameters. The optimum parameters to achieve maximum density and well-defined hexagonally shaped nanorods were a precursor molarity of 0.2 M, an injection flow rate of 6 ml/min, an injection time of 10 min, and a substrate temperature of 250-355 °C. Based on the experimental results, the response surface methodology (RSM) was used to model and optimize the independent pyrolysis parameters using the Box-Behnken design. Here, the responses, i.e., the nanostructure density, size, and shape factor, are evaluated. All of the computations were performed using the Design-Expert software package. Analysis of variance (ANOVA) was used to evaluate the results of the model and to determine the significant values for the independent pyrolysis parameters. The evolution of zinc oxide (ZnO) structures are well explained by the developed modelling which confirms that RSM is a reliable tool for the modelling and optimization of the pyrolysis parameters and prediction of nanostructure sizes and shapes.

  17. Financial development and corporate growth in the EU single market

    Czech Academy of Sciences Publication Activity Database

    Bena, J.; Jurajda, Štěpán

    2011-01-01

    Roč. 78, č. 311 (2011), s. 401-428 ISSN 0013-0427 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : financial development * corporate growth * access to financial markets Subject RIV: AH - Economics Impact factor: 1.152, year: 2011

  18. Identification of single nucleotide polymorphism of growth hormone ...

    African Journals Online (AJOL)

    Yurnalis

    The pupose of this study was to identify genetic polymorphisms of bovine growth hormone gene exon. 4, and intron 4 in local cattle breeds in West Sumatera Province of Indonesia. DNA was isolated from 60 blood samples and polymerase chain reaction (PCR) product of GH5 fragment (366 bp) were directly sequenced.

  19. Investigation of grain competitive growth during directional solidification of single-crystal nickel-based superalloys

    International Nuclear Information System (INIS)

    Zhao, Xinbao; Liu, Lin; Zhang, Jun

    2015-01-01

    Grain competitive growth of nickel-based single-crystal superalloys during directional solidification was investigated. A detailed characterization of bi-crystals' competitive growth was performed to explore the competitive grain evolution. It was found that high withdrawal rate improved the efficiency of grain competitive growth. The overgrowth rate was increased when the misorientation increased. Four patterns of grain competitive growth with differently oriented dispositions were characterized. The results indicated that the positive branching of the dendrites played a significant role in the competitive growth process. The effect of crystal orientation and heat flow on the competitive growth can be attributed to the blocking mechanism between the adjacent grains. (orig.)

  20. Variation in growth of infants with a single ventricle.

    Science.gov (United States)

    Anderson, Jeffrey B; Iyer, Srikant B; Schidlow, David N; Williams, Richard; Varadarajan, Kartik; Horsley, Megan; Slicker, Julie; Pratt, Jesse; King, Eileen; Lannon, Carole

    2012-07-01

    The study goal was to evaluate interstage growth variation among sites participating in the National Pediatric Cardiology Quality Improvement Collaborative registry caring for infants with hypoplastic left heart syndrome and to identify nutritional practices common among sites achieving best growth outcomes. This was a retrospective analysis of infants in the registry who had presented due to their superior cavopulmonary connection (SCPC) and whose surgical site had enrolled ≥ 4 eligible patients in the registry. The primary outcome variable was weight-for-age z-score (WAZ) change between Norwood discharge and presentation for SCPC (interstage period). Blinded, structured interviews were performed with each site regarding site-specific nutritional practices. Practices common among sites with positive interstage WAZ changes were identified. Sixteen centers enrolled 132 infants from December 2008 through December 2010. Median age at SCPC was 5 months (2.6-12.6), and median interstage WAZ change was -0.29 (-3.2 to 2.3). Significant variation in WAZ changes among sites was demonstrated (P < .001). Sites that used standard feeding evaluation prior to Norwood discharge and that closely monitored for specific weight gain/loss red flags in the interstage period demonstrated significantly better patient growth than those that did not use these practices (P = .002). Considerable variation exists in interstage growth among patients receiving care at these 16 surgical sites. Standardization of interstage nutritional management with focus on best nutritional practices may lead to improved growth in this high-risk population of infants. Copyright © 2012 Mosby, Inc. All rights reserved.

  1. Evaluation of yeast single cell protein (SCP) diets on growth ...

    African Journals Online (AJOL)

    An investigation was carried out on the possibility of replacing fishmeal with graded levels of yeast single cell protein (SCP; 10, 20, 30, 40 and 50%) in ... that the 50% yeast SCP fed fish had the highest percentage of body protein (55.35%), but with a lower amount of fat at the end of the feeding trial compared to the control.

  2. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    menon, especially those involved in the gel technique. With an aim of controlling nucleation and improving the size, in the present study, we have grown pure calcium tartrate tetrahydrate single crystals using calcium formate mixed with formic acid as the supernatant solution. The grown crystals have been characterized by ...

  3. Evaluation of yeast single cell protein (SCP) diets on growth ...

    African Journals Online (AJOL)

    Jane

    An investigation was carried out on the possibility of replacing fishmeal with graded levels of yeast single cell protein (SCP; 10, 20, 30, 40 and 50%) in isonitrogenous feed formulations (30% protein) in the diet of Oreochromis niloticus fingerlings for a period of 12 weeks. The control diet had fishmeal as the primary protein ...

  4. Single Nucleotide Polymorphisms in Growth Hormone Gene and Their Association with Growth Traits in Siniperca chuatsi (Basilewsky

    Directory of Open Access Journals (Sweden)

    Changxu Tian

    2014-04-01

    Full Text Available Growth hormone (GH has been considered as a candidate gene for growth traits in fish. In this study, polymorphisms of the GH gene were evaluated for associations with growth traits in 282 Siniperca chuatsi individuals. Using directly sequencing, four single nucleotide polymorphisms (SNPs were identified in GH gene, with two mutations in intron 4 (g.4940A>C, g.4948A>T, one mutation in exon 5 (g.5045T>C and one in intron 5 (g.5234T>G. Notably, three of them were significantly associated with growth performance, particularly for g.4940A>C which was highly correlated with all the four growth traits. In conclusion, our results demonstrated that these SNPs in GH gene could influence growth performance of S.chuatsi and could be used for marker-assisted selection (MAS in this species.

  5. Assembly of Complex Nano-Structure from Single Atoms —Chemical Identification, Manipulation and Assembly by AFM—

    Science.gov (United States)

    Morita, Seizo; Sugimoto, Yoshiaki; Ooyabu, Noriaki; Custance, Óscar; Abe, Masayuki; Pou, Pablo; Jelinek, Pavel; Pérez, Rubén

    An atomic force microscope (AFM) under noncontact and nearcontact regions operated at room-temperature (RT) in ultrahigh vacuum, is used as a tool for topography-based atomic discrimination and atomic-interchange manipulations of two intermixed atomic species on semiconductor surfaces. Noncontact AFM topography based site-specific force curves provide the chemical covalent bonding forces between the tip apex and the atoms at the surface. Here, we introduced an example related to topography-based atomic discrimination using selected Sn and Si adatoms in Sn/Si(111)-(√3 ×√3 ) surface. Recently, under nearcontact region, we found a lateral atom-interchange manipulation phenomenon at RT in Sn/Ge(111)-c(2×8) intermixed sample. This phenomenon can interchange an embedded Sn atom with a neighbor Ge atom at RT. Using the vector scan method under nearcontact region, we constructed “Atom Inlay”, that is, atom letters “Sn” consisted of 19 Sn atoms embedded in Ge(111)-c(2×8) substrate. Using these methods, now we can assemble compound semiconductor nanostructures atom-by-atom.

  6. Controlling Fundamental Fluctuations for Reproducible Growth of Large Single-Crystal Graphene.

    Science.gov (United States)

    Guo, Wei; Wu, Bin; Wang, Shuai; Liu, Yunqi

    2018-02-27

    The controlled growth of graphene by the chemical vapor deposition method is vital for its various applications; however, the reproducibility remains a great challenge. Here, using single-crystal graphene growth on a Cu surface as a model system, we demonstrate that a trace amount of H 2 O and O 2 impurity gases in the reaction chamber is key for the large fluctuation of graphene growth. By precisely controlling their parts per million level concentrations, centimeter-sized single-crystal graphene is obtained in a reliable manner with a maximum growth rate up to 190 μm min -1 . The roles of oxidants are elucidated as an effective modulator for both graphene nucleation density and growth rate. This control is more fundamental for reliable growth of graphene beyond previous findings and is expected to be useful for the growth of various 2D materials that are also sensitive to trace oxidant impurities.

  7. Alkali-etching growth of nest-like Ag@mTiO2 hierarchical nanostructures and their potential applications.

    Science.gov (United States)

    Zhang, Zongnan; Zhang, Haijiao

    2017-06-01

    Porous nanomaterials have attracted extensive interests in adsorption, catalysis, biosensors, and biomedicine due to their high surface area, well-defined pore structure and tunable pore size. However, how to obtain porous nanomaterials of desirable component and unique structure with multifunctionalities and synergetic properties is still a great challenge. In this work, a novel nest-like Ag@mTiO 2 hierarchical nanostructure with Ag nanoparticle as the core and a mesoporous crystalline TiO 2 as the protective shell was successfully prepared by layer-by-layer assembly technique and alkali-etching hydrothermal route. By simply changing the conditions of alkali etching, different nanostructures could be obtained, such as core-shell or rattle type. In the process, the thickness of coating silica layer and TiO 2 shell both played important roles for the formation of desired nanostructures. The as-prepared products had a large specific surface area of 301m 2 /g and a tailored TiO 2 outer shell. Raman spectra results showed perfect SERS signal of the tags enhanced and remained good stability even after one month. Doxycycline (Doxy) was chosen to evaluate their drug loading and controlled release properties. The results indicated that the obtained Ag@mTiO 2 nanoparticles exhibited good biocompatibility and excellent drug-loading capacity. Consequently, they are also expected to serve as ideal candidates for more potential applications including photocatalysis, drug controlled release, biosensor and cell imaging, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Gelatin Nanostructured Lipid Carriers Incorporating Nerve Growth Factor Inhibit Endoplasmic Reticulum Stress-Induced Apoptosis and Improve Recovery in Spinal Cord Injury.

    Science.gov (United States)

    Zhu, Si-Pin; Wang, Zhou-Guang; Zhao, Ying-Zheng; Wu, Jiang; Shi, Hong-Xue; Ye, Li-Bing; Wu, Fen-Zan; Cheng, Yi; Zhang, Hong-Yu; He, Songbin; Wei, Xiaojie; Fu, Xiao-Bing; Li, Xiao-Kun; Xu, Hua-Zi; Xiao, Jian

    2016-09-01

    Clinical translation of growth factor therapies faces multiple challenges; the most significant one is the short half-life of the naked protein. Gelatin nanostructured lipid carriers (GNLs) had previously been used to encapsulate the basic fibroblast growth factor to enhance the functional recovery in hemiparkinsonian rats. In this research, we comparatively study the enhanced therapy between nerve growth factor (NGF) loaded GNLs (NGF-GNLs) and NGF only in spinal cord injury (SCI). The effects of NGF-GNLs and NGF only were tested by the Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test, and footprint analysis. Western blot analysis and immunofluorescent staining were further performed to identify the expression of ER stress-related proteins, neuron-specific marker neuronal nuclei (NeuN), and growth-associated protein 43 (GAP43). Correlated downstream signals Akt/GSK-3β and ERK1/2 were also analyzed with or without inhibitors. Results showed that NGF-GNLs, compared to NGF only, enhanced the neuroprotection effect in SCI rats. The ER stress-induced apoptosis response proteins CHOP, GRP78 and caspase-12 inhibited by NGF-GNL treatment were more obvious. Meanwhile, NGF-GNLs in the recovery of SCI are related to the inhibition of ER stress-induced cell death via the activation of downstream signals PI3K/Akt/GSK-3β and ERK1/2.

  9. Surface growth mechanisms and structural faulting in the growth of large single and spherulitic titanosilicate ETS-4 crystals

    Science.gov (United States)

    Miraglia, Peter Q.; Yilmaz, Bilge; Warzywoda, Juliusz; Sacco, Albert

    2004-10-01

    Morphological, surface and crystallographic analyses of titanosilicate ETS-4 products, with diverse habits ranging from spherulitic particles composed of submicron crystallites to large single crystals, are presented. Pole figures revealed that crystal surfaces with a-, b- and c- axes corresponded to , and directions, respectively. Thus, technologically important 8-membered ring pores and titania chains in ETS-4 run along the b-axis of single crystals and terminate at the smallest crystal face. Height of the spiral growth steps observed on {1 0 0} and {0 0 1} surfaces corresponded to the interplanar spacings associated with their crystallographic orientation, and is equivalent to the thickness of building units that form the ETS-4 framework. Data suggest that the more viscous synthesis mixtures, with a large driving force for growth, increased the two- and three-dimensional nucleation, while limiting the transport of nutrients to the growth surface. These conditions increase the tendency for stacking fault formation on {1 0 0} surfaces and small angle branching, which eventually results in spherulitic growth. The growth of high quality ETS-4 single crystals (from less viscous synthesis mixtures) occurred at lower surface nucleation rates. Data suggest that these high quality, large crystals grew due to one-dimensional nucleation at spiral hillocks, and indicate that under these conditions un-faulted growth is preferred.

  10. Localization microscopy of DNA in situ using Vybrant{sup ®} DyeCycle™ Violet fluorescent probe: A new approach to study nuclear nanostructure at single molecule resolution

    Energy Technology Data Exchange (ETDEWEB)

    Żurek-Biesiada, Dominika [Laboratory of Cell Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków (Poland); Szczurek, Aleksander T. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Prakash, Kirti [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Institute for Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg (Germany); Mohana, Giriram K. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Lee, Hyun-Keun [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany); Roignant, Jean-Yves [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Birk, Udo J. [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany); Dobrucki, Jurek W., E-mail: jerzy.dobrucki@uj.edu.pl [Laboratory of Cell Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków (Poland); Cremer, Christoph, E-mail: c.cremer@imb-mainz.de [Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz (Germany); Institute for Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg (Germany); Department of Physics, University of Mainz (JGU), Staudingerweg 7, 55128 Mainz (Germany)

    2016-05-01

    Higher order chromatin structure is not only required to compact and spatially arrange long chromatids within a nucleus, but have also important functional roles, including control of gene expression and DNA processing. However, studies of chromatin nanostructures cannot be performed using conventional widefield and confocal microscopy because of the limited optical resolution. Various methods of superresolution microscopy have been described to overcome this difficulty, like structured illumination and single molecule localization microscopy. We report here that the standard DNA dye Vybrant{sup ®} DyeCycle™ Violet can be used to provide single molecule localization microscopy (SMLM) images of DNA in nuclei of fixed mammalian cells. This SMLM method enabled optical isolation and localization of large numbers of DNA-bound molecules, usually in excess of 10{sup 6} signals in one cell nucleus. The technique yielded high-quality images of nuclear DNA density, revealing subdiffraction chromatin structures of the size in the order of 100 nm; the interchromatin compartment was visualized at unprecedented optical resolution. The approach offers several advantages over previously described high resolution DNA imaging methods, including high specificity, an ability to record images using a single wavelength excitation, and a higher density of single molecule signals than reported in previous SMLM studies. The method is compatible with DNA/multicolor SMLM imaging which employs simple staining methods suited also for conventional optical microscopy. - Highlights: • Super-resolution imaging of nuclear DNA with Vybrant Violet and blue excitation. • 90nm resolution images of DNA structures in optically thick eukaryotic nuclei. • Enhanced resolution confirms the existence of DNA-free regions inside the nucleus. • Optimized imaging conditions enable multicolor super-resolution imaging.

  11. GROWTH RATE DISTRIBUTION OF BORAX SINGLE CRYSTALS ON THE (001 FACE UNDER VARIOUS FLOW RATES

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax single crystals from aqueous solutions at various flow rates in the (001 direction were measured using in situ cell method. From the growth rate data obtained, the growth rate distribution of borax crystals was investigated using Minitab Software and SPSS Software at relative supersaturation of 0807 and temperature of 25 °C. The result shows that normal, gamma, and log-normal distribution give a reasonably good fit to GRD. However, there is no correlation between growth rate distribution and flow rate of solution.   Keywords: growth rate dispersion (GRD, borax, flow rate

  12. Growth of single T cells and single thymocytes in a high cloning efficiency filler-cell free microculture system.

    Science.gov (United States)

    Chen, W F; Ewing, T; Scollay, R; Shortman, K

    1988-01-01

    A high cloning-efficiency microculture system is described in which single T cells, stimulated to divide by phorbol ester and calcium ionophore, grow rapidly under the influence of purified growth factors in the absence of other cells. The kinetics of clonal growth has been monitored over a five day period by phase-contrast microscopy. Mature peripheral T cells, and mature subpopulations from the thymus, responded with a cloning efficiency over 80%; they required IL-2 as a minimum but several other factors enhanced growth. Ly2+L3T4- thymocytes (mean doubling time 10.4 hr) grew more rapidly than Ly2-L3T4+ thymocytes (mean doubling time 15.2 hr). Early (Ly2-L3T4-) thymocytes responded with a cloning efficiency of 60%; their efficient growth was dependent on both IL-1 and IL-2. The typical Ly2+L3T4+ cortical thymocyte did not grow under these conditions.

  13. A Review on the Low-Dimensional and Hybridized Nanostructured Diamond Films

    Directory of Open Access Journals (Sweden)

    Hongdong Li

    2015-01-01

    Full Text Available In the last decade, besides the breakthrough of high-rate growth of chemical vapor deposited single-crystal diamonds, numerous nanostructured diamond films have been rapidly developed in the research fields of the diamond-based sciences and industrial applications. The low-dimensional diamonds of two-dimensional atomic-thick nanofilms and nanostructural diamond on the surface of bulk diamond films have been theoretically and experimentally investigated. In addition, the diamond-related hybrid nanostructures of n-type oxide/p-type diamond and n-type nitride/p-type diamond, having high performance physical and chemical properties, are proposed for further applications. In this review, we first briefly introduce the three categories of diamond nanostructures and then outline the current advances in these topics, including their design, fabrication, characterization, and properties. Finally, we address the remaining challenges in the research field and the future activities.

  14. Silicon-embedded copper nanostructure network for high energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tianyue

    2018-01-23

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  15. Silicon-embedded copper nanostructure network for high energy storage

    Science.gov (United States)

    Yu, Tianyue

    2016-03-15

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  16. Suppressing Lithium Dendrite Growth with a Single-Component Coating.

    Science.gov (United States)

    Liu, Haodong; Zhou, Hongyao; Lee, Byoung-Sun; Xing, Xing; Gonzalez, Matthew; Liu, Ping

    2017-09-13

    A single-component coating was formed on lithium (Li) metal in a lithium iodide/organic carbonate [dimethyl carbonate (DMC) and ethylene carbonate (EC)] electrolyte. LiI chemically reacts with DMC to form lithium methyl carbonate (LMC), which precipitates and forms the chemically homogeneous coating layer on the Li surface. This coating layer is shown to enable dendrite-free Li cycling in a symmetric Li∥Li cell even at a current density of 3 mA cm -2 . Adding EC to DMC modulates the formation of LMC, resulting in a stable coating layer that is essential for long-term Li cycling stability. Furthermore, the coating can enable dendrite-free cycling after being transferred to common LiPF 6 /carbonate electrolytes, which are compatible with metal oxide cathodes.

  17. Phase diagram of interfacial growth modes by vapor deposition and its application for ZnO nanostructures

    Science.gov (United States)

    Shu, Da-Jun; Xiong, Xiang; Liu, Ming; Wang, Mu

    2017-09-01

    Interfacial growth from vapor has been extensively studied. However, a straightforward picture of the growth mode under different growth conditions is still lacking. In this paper, we develop a comprehensive interfacial growth theory based on the stochastic approach. Using a critical interisland separation, we construct a general phase diagram of the growth modes. It has been revealed that if the Ehrlich-Schwoebel barrier EES is smaller than a critical value, the interfacial growth proceeds in a layer-by-layer (LBL) mode at any deposition rate. However, if EES is larger than the critical value, LBL growth occurs only at very small or very large deposition rates relative to the intralayer hopping rate, and multilayer (ML) growth occurs at a moderate deposition rate. Experiments with zinc oxide growth by chemical vapor deposition have been designed to qualitatively demonstrate the theoretical model. By changing the flux of the carrier gas (nitrogen gas) in chemical vapor deposition, we realize LBL, ML, and then reentrance of LBL homoepitaxial growth of ZnO successively. Moreover, we find that surface kinetics of ZnO is suppressed by decreasing oxygen partial pressure by comparing the experimental observations and theoretical models, which is supported by our recent first-principles calculations. Since the influence of the substrate and the growth species on growth can approximately be represented by binding energy and surface kinetics, we suggest that the phase diagram is essential for interfacial growth of different materials by vapor deposition.

  18. Growth and study of barium oxalate single crystals in agar gel

    Indian Academy of Sciences (India)

    Unknown

    In the present work, agar–agar gel (Brezina and Harvan- kova 1991; Agrawal et al 1999) was preferentially used for the growth of crystals by single and double diffusion tech- niques. A test tube having 25 cm in length and 2⋅5 cm in dia- meter was employed. In single diffusion, hot aqueous agar gel and oxalic acid solution ...

  19. A structurally based analytic model of growth and biomass dynamics in single species stands of conifers

    Science.gov (United States)

    Robin J. Tausch

    2015-01-01

    A theoretically based analytic model of plant growth in single species conifer communities based on the species fully occupying a site and fully using the site resources is introduced. Model derivations result in a single equation simultaneously describes changes over both, different site conditions (or resources available), and over time for each variable for each...

  20. Mechanical design of DNA nanostructures.

    Science.gov (United States)

    Castro, Carlos E; Su, Hai-Jun; Marras, Alexander E; Zhou, Lifeng; Johnson, Joshua

    2015-04-14

    Structural DNA nanotechnology is a rapidly emerging field that has demonstrated great potential for applications such as single molecule sensing, drug delivery, and templating molecular components. As the applications of DNA nanotechnology expand, a consideration of their mechanical behavior is becoming essential to understand how these structures will respond to physical interactions. This review considers three major avenues of recent progress in this area: (1) measuring and designing mechanical properties of DNA nanostructures, (2) designing complex nanostructures based on imposed mechanical stresses, and (3) designing and controlling structurally dynamic nanostructures. This work has laid the foundation for mechanically active nanomachines that can generate, transmit, and respond to physical cues in molecular systems.

  1. The growth of single crystals of Ni-W alloy under conditions of high temperature gradient

    International Nuclear Information System (INIS)

    Azhazha, V.M.; Gorbenko, Yu.V.; Kovtun, G.P.; Ladygin, A.N.; Malykhin, D.G.; Rudycheva, T.Yu.; Sverdlov, V.Ya.; Shcherban', A.P.; Zhemanyuk, P.D.; Klochikhin, V.V.

    2004-01-01

    The structure of single crystals of the NV-4 nickel alloy containing 32-36 wt % W is investigated. The temperature gradient at the crystallization front and the velocity of the crystallization front are the variable parameters of directional crystallization. The degrees of structural perfection of the single crystals grown under different conditions are compared. The crystallization parameters providing growth of single crystals that have high structural perfection and can be successfully used as seeds for the growth of single-crystal blades are determined. Typical defects formed upon directional crystallization of single crystals of the Ni-W (35 wt %) alloy are examined. The studied defects are classified, and the factors responsible for the disturbance of the single-crystal structure are analyzed

  2. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank

    2012-01-01

    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  3. Controlled growth of epitaxial CeO2 thin films with self-organized nanostructure by chemical solution method

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude

    2013-01-01

    a fluorite structure but exhibits an alternative in-plane texture with eight fold symmetry on the surface. According to phase and texture stability studies, these off-stoichiometric phases gradually transform back to fully oxidized CeO2 with a 45° rotated cube texture during storage in ambient air. Moreover......Chemical solution deposition is a versatile technique to grow oxide thin films with self-organized nanostructures. Morphology and crystallographic orientation control of CeO2 thin films grown on technical NiW substrates by a chemical solution deposition method are achieved in this work. Based......, the morphology of the CeO2 thin films is controlled by precisely regulating the film thickness and crystallization temperature. A temperature-induced transition from the commonly observed granular grain to an atomically flat surface is found in the CeO2–NiW constitution. Cross-sectional transmission electron...

  4. Electrochemical growth of high-aspect ratio nanostructured silver chloride on silver and its application to miniaturized reference electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Safari, S; Selvaganapathy, P R [Department of Mechanical Engineering, McMaster University, Hamilton, ON, L8S 4L7 (Canada); Derardja, A [Faculty of Science and Engineering, University of Batna (Algeria); Deen, M J, E-mail: selvaga@mcmaster.ca, E-mail: jamal@mcmaster.ca [Electrical and Computer Engineering, McMaster University, Hamilton, ON, L8S 4L8 (Canada)

    2011-08-05

    The sensitivity of many biological and chemical sensors is critically dependent on the stability of the potential of the reference electrode being used. The stability of a reference electrode's potential is highly influenced by the properties of its surface. In this paper, for the first time, the formation of nanosheets of silver chloride on silver wire is observed and controlled using high anodic constant potential (>0.5 V) and pulsed electrodeposition. The resulting nanostructured morphology substantially improves the electrode's potential stability in comparison with the conventional globular surface structure. The increased stability is attributed to the increase in the surface area of the silver chloride produced by the nanosheet formation.

  5. Tunable top-down fabrication and functional surface coating of single-crystal titanium dioxide nanostructures and nanoparticles

    NARCIS (Netherlands)

    Dekker, N.H.; Ha, S.; Janissen, R.; Ussembayev, Y.; van Oene, M.M.; Solano Hermosilla, B.P.

    2016-01-01

    Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and

  6. Plasma enhanced chemical vapor deposition of metalboride interfacial layers as diffusion barriers for nanostructured diamond growth on cobalt containing alloys CoCrMo and WC-Co

    Science.gov (United States)

    Johnston, Jamin M.

    This work is a compilation of theory, finite element modeling and experimental research related to the use of microwave plasma enhanced chemical vapor deposition (MPECVD) of diborane to create metal-boride surface coatings on CoCrMo and WC-Co, including the subsequent growth of nanostructured diamond (NSD). Motivation for this research stems from the need for wear resistant coatings on industrial materials, which require improved wear resistance and product lifetime to remain competitive and satisfy growing demand. Nanostructured diamond coatings are a promising solution to material wear but cannot be directly applied to cobalt containing substrates due to graphite nucleation. Unfortunately, conventional pre-treatment methods, such as acid etching, render the substrate too brittle. Thus, the use of boron in a MPECVD process is explored to create robust interlayers which inhibit carbon-cobalt interaction. Furthermore, modeling of the MPECVD process, through the COMSOL MultiphysicsRTM platform, is performed to provide insight into plasma-surface interactions using the simulation of a real-world apparatus. Experimental investigation of MPECVD boriding and NSD deposition was conducted at surface temperatures from 700 to 1100 °C. Several well-adhered metal-boride surface layers were formed: consisting of CoB, CrB, WCoB, CoB and/or W2CoB2. Many of the interlayers were shown to be effective diffusion barriers against elemental cobalt for improving nucleation and adhesion of NSD coatings; diamond on W2CoB2 was well adhered. However, predominantly WCoB and CoB phase interlayers suffered from diamond film delamination. Metal-boride and NSD surfaces were evaluated using glancing-angle x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), cross-sectional scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), micro-Raman spectroscopy, nanoindentation, scratch testing and epoxy pull testing. COMSOL MultiphysicsRTM was used to construct a

  7. Optoelectronic properties of semiconductor nanostructures

    Science.gov (United States)

    Maher, Kristin Nicole

    Semiconductor nanostructures have unique optical and electronic properties that have inspired research into their technological applications and basic science. This thesis presents approaches to the fabrication and characterization of optoelectronic devices incorporating individual semiconductor nanostructures. Nanowires of the II-VI semiconductors CdSe and CdS were synthesized using nanoparticle-catalysed solution-liquid-solid growth. Single-component nanowires and heterostructure nanowires with axial compositional modulation were generated using this method. Individual nanowires and nanocrystals were then incorporated into devices with a three-terminal field-effect transistor geometry. An experimental platform was developed which allows for simultaneous electrical characterization of devices and measurement of their optical properties. This setup enables the measurement of spatially and spectrally resolved electroluminescence (EL) and photoluminescence (PL) from individual nanostructures and nanostructure devices. It also allows the measurement of photon coincidence histograms for emitted light and the acquisition of photocurrent images via laser scanning microscopy. Electroluminescence was observed from individual CdSe nanocrystals contacted by gold electrodes. Concomitant transport measurements at low temperature showed clear evidence of Coulomb blockade at low bias voltage, with light only emitted from devices exhibiting asymmetric tunnel couplings between the nanocrystal and electrodes. Combined analyses of the data indicate that the resistances of the tunnel barriers are bias voltage dependent and that light emission results from the inelastic scattering of tunneling electrons. Three-terminal devices incorporating individual CdSe nanoNvires exhibited EL localized near the positively-biased electrode. Characterization of these devices by scanning photocurrent microscopy (SPCM) and Kelvin probe microscopy (KPM) indicates that while there are n-type Schottky

  8. Metal chalcogenide nanostructures for renewable energy applications

    CERN Document Server

    Qurashi, Ahsanulhaq

    2014-01-01

    This first ever reference book that focuses on metal chalcogenide semiconductor nanostructures for renewable energy applications encapsulates the state-of-the-art in multidisciplinary research on the metal chalcogenide semiconductor nanostructures (nanocrystals, nanoparticles, nanorods, nanowires,  nanobelts, nanoflowers, nanoribbons and more).  The properties and synthesis of a class of nanomaterials is essential to renewable energy manufacturing and this book focuses on the synthesis of metal chalcogendie nanostructures, their growth mechanism, optical, electrical, and other important prop

  9. Interface debond crack growth in tension–tension cyclic loading of single fiber polymer composites

    DEFF Research Database (Denmark)

    Pupurs, Andrejs; Goutianos, Stergios; Brøndsted, Povl

    2013-01-01

    Fiber/matrix interface debond crack growth from a fiber break is defined as one of the key mechanisms of fatigue damage in unidirectional composites. Considering debond as an interface crack its growth in cyclic loading is analyzed utilizing a power law, where the debond growth rate is a power...... for glass fiber/epoxy single fiber composites. Analytical method in the steady-state growth region and FEM for short debonds are combined for calculating the strain energy release rate of the growing debond crack. Interface failure parameters in fatigue are determined by fitting the modeling...

  10. Factors affecting growth in infants with single ventricle physiology: a report from the Pediatric Heart Network Infant Single Ventricle Trial.

    Science.gov (United States)

    Williams, Richard V; Zak, Victor; Ravishankar, Chitra; Altmann, Karen; Anderson, Jeffrey; Atz, Andrew M; Dunbar-Masterson, Carolyn; Ghanayem, Nancy; Lambert, Linda; Lurito, Karen; Medoff-Cooper, Barbara; Margossian, Renee; Pemberton, Victoria L; Russell, Jennifer; Stylianou, Mario; Hsu, Daphne

    2011-12-01

    To describe growth patterns in infants with single ventricle physiology and determine factors influencing growth. Data from 230 subjects enrolled in the Pediatric Heart Network Infant Single Ventricle Enalapril Trial were used to assess factors influencing change in weight-for-age z-score (z) from study enrollment (0.7 ± 0.4 months) to pre-superior cavopulmonary connection (SCPC; 5.1 ± 1.8 months, period 1) and pre-SCPC to final study visit (14.1 ± 0.9 months, period 2). Predictor variables included patient characteristics, feeding regimen, clinical center, and medical factors during neonatal (period 1) and SCPC hospitalizations (period 2). Univariate regression analysis was performed, followed by backward stepwise regression and bootstrapping reliability to inform a final multivariable model. Weights were available for 197 of 230 subjects for period 1 and 173 of 197 subjects for period 2. For period 1, greater gestational age, younger age at study enrollment, tube feeding at neonatal hospitalization discharge, and clinical center were associated with a greater negative z (poorer growth) in multivariable modeling (adjusted R(2) = 0.39, P SCPC and greater daily caloric intake were associated with greater positive z (better growth; R(2) = 0.10, P = .002). Aggressive nutritional support and earlier SCPC are modifiable factors associated with a favorable change in weight-for-age z-score. Copyright © 2011 Mosby, Inc. All rights reserved.

  11. Factors Impacting Growth in Infants with Single Ventricle Physiology: A Report from Pediatric Heart Network Infant Single Ventricle Trial

    Science.gov (United States)

    Williams, Richard V.; Zak, Victor; Ravishankar, Chitra; Altmann, Karen; Anderson, Jeffrey; Atz, Andrew M.; Dunbar-Masterson, Carolyn; Ghanayem, Nancy; Lambert, Linda; Lurito, Karen; Medoff-Cooper, Barbara; Margossian, Renee; Pemberton, Victoria L.; Russell, Jennifer; Stylianou, Mario; Hsu, Daphne

    2011-01-01

    Objectives To describe growth patterns in infants with single ventricle physiology and determine factors influencing growth. Study design Data from 230 subjects enrolled in the Pediatric Heart Network Infant Single Ventricle Enalapril Trial were used to assess factors influencing change in weight-for-age z-score (Δz) from study enrollment (0.7 ± 0.4 months) to pre-superior cavopulmonary connection (SCPC) (5.1 ± 1.8 months, period 1), and pre-SCPC to final study visit (14.1 ± 0.9 months, period 2). Predictor variables included patient characteristics, feeding regimen, clinical center, and medical factors during neonatal (period 1) and SCPC hospitalizations (period 2). Univariate regression analysis was performed, followed by backward stepwise regression and bootstrapping reliability to inform a final multivariable model. Results Weights were available for 197/230 subjects for period 1 and 173/197 for period 2. For period 1, greater gestational age, younger age at study enrollment, tube feeding at neonatal discharge, and clinical center were associated with a greater negative Δz (poorer growth) in multivariable modeling (adjusted R2 = 0.39, p SCPC and greater daily caloric intake were associated with greater positive Δz (better growth) (R2 = 0.10, p = 0.002). Conclusions Aggressive nutritional support and earlier SCPC are modifiable factors associated with a favorable change in weight-for-age z-score. PMID:21784436

  12. Relaxation in magnetic nanostructures

    International Nuclear Information System (INIS)

    Novak, M.A.; Folly, W.S.D.; Sinnecker, J.P.; Soriano, S.

    2005-01-01

    Nanostructured magnetic materials present a wide range of magnetic relaxation phenomena. One problem in studying nanomagnetic granular materials is the strong dependence of the relaxation with the anisotropy barrier which, even for systems with narrow size distributions, brings difficulties in the analysis of the experimental data. Molecular magnetism, with the chemists' bottom-up approach to build molecular nanostructures, provides this field with some beautiful model systems, well ordered crystals of single molecule magnets, single molecule chains, molecular magnetic multilayers and others novelties to appear. Most of these systems present slow relaxation and the study of these well-characterized nanomaterials may elucidate many features that are difficult to grasp in the non molecular materials

  13. Single nucleotide polymorphisms in intron 1 and intron 2 of Larimichthys crocea growth hormone gene are correlated with growth traits

    Science.gov (United States)

    Ni, Jing; You, Feng; Xu, Jianhe; Xu, Dongdong; Wen, Aiyun; Wu, Zhihao; Xu, Yongli; Zhang, Peijun

    2012-03-01

    The growth hormone gene ( GH) affects animal growth and is a potential target for genetic studies of variation related to growth traits. In this study, we analyzed single nucleotide polymorphisms (SNPs) in GH intron regions and their associations with growth traits in large yellow croaker, Larimichthys crocea, from Zhejiang and Fujian stocks. The results of PCR-single strand conformation polymorphism showed two haplotypes of intron 1, named AA and AB genotypes, in Zhejiang stock. AB exhibited an SNP at position 196 (G→A) that was negatively correlated with body height and positively correlated with standard length/body height ( P≤0.05). Two different genotypes, CC and CD, were identified in intron 2 in Fujian stock, with CD showing an SNP at position 692 (T→C). The CD genotype had a significantly positive correlation with both weight and total length ( P≤0.01). These basic data highlight the potential for using GH as a genetic marker of fish growth in marker assisted selection.

  14. Chirality-Dependent Vapor-Phase Epitaxial Growth and Termination of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Liu, Bilu; Liu, Jia; Zhou, Chongwu; USC nanolab Team

    2014-03-01

    Chirality-pure single-wall carbon nanotubes are highly desired for both fundamental study and many of their technological applications. Recently, we have shown that chirality-pure short nanotubes can be used as seeds for vapor-phase epitaxial cloning growth, opening up a new route toward chirality-controlled carbon nanotube synthesis. Nevertheless, the yield of vapor-phase epitaxial growth is rather limited at the present stage, due to the lack of mechanistic understanding of the process. Here we report chirality-dependent growth kinetics and termination mechanism for the vapor-phase epitaxial growth of seven single- chirality nanotubes of (9, 1), (6, 5), (8, 3), (7, 6), (10, 2), (6, 6), and (7, 7), covering near zigzag, medium chiral angle, and near armchair semiconductors, as well as armchair metallic nanotubes. Our results reveal that the growth rates of nanotubes increase with their chiral angles while the active lifetimes of the growth hold opposite trend. Consequently, the chirality distribution of a nanotube ensemble is jointly determined by both growth rates and lifetimes. These results correlate nanotube structures and properties with their growth behaviors and deepen our understanding of chirality-controlled growth of nanotubes.

  15. Single-Cell Microfluidics to Study the Effects of Genome Deletion on Bacterial Growth Behavior.

    Science.gov (United States)

    Yuan, Xiaofei; Couto, Jillian M; Glidle, Andrew; Song, Yanqing; Sloan, William; Yin, Huabing

    2017-12-15

    By directly monitoring single cell growth in a microfluidic platform, we interrogated genome-deletion effects in Escherichia coli strains. We compared the growth dynamics of a wild type strain with a clean genome strain, and their derived mutants at the single-cell level. A decreased average growth rate and extended average lag time were found for the clean genome strain, compared to those of the wild type strain. Direct correlation between the growth rate and lag time of individual cells showed that the clean genome population was more heterogeneous. Cell culturability (the ratio of growing cells to the sum of growing and nongrowing cells) of the clean genome population was also lower. Interestingly, after the random mutations induced by a glucose starvation treatment, for the clean genome population mutants that had survived the competition of chemostat culture, each parameter markedly improved (i.e., the average growth rate and cell culturability increased, and the lag time and heterogeneity decreased). However, this effect was not seen in the wild type strain; the wild type mutants cultured in a chemostat retained a high diversity of growth phenotypes. These results suggest that quasi-essential genes that were deleted in the clean genome might be required to retain a diversity of growth characteristics at the individual cell level under environmental stress. These observations highlight that single-cell microfluidics can reveal subtle individual cellular responses, enabling in-depth understanding of the population.

  16. Synthesis of One Dimensional Gold Nanostructures

    Directory of Open Access Journals (Sweden)

    Hongchen Li

    2010-01-01

    Full Text Available Gold nanostructures with shapes of rod, dumbbells, and dog bone have been fabricated by an improved seed-mediated method. It is found that the pH change (the addition of HNO3 or HCl and the presence of Ag+ ions have a great influence on the growth process and aspect ratios of these Au nanocrystals. UV-Vis-NIR absorption spectra for the Au colloidal show that the transverse plasmon absorption band locates at ~520 nm, while the longitudinal plasmon absorption band shifts in a wide spectra region of 750–1100 nm. The obtained Au nanostructures have been investigated by transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray diffractometer. Based on the characterizations and FDTD simulations, most of the obtained Au nanorods are single crystals, possessing an octagonal cross-section bounded by {110} and {100} faces. One model for the anisotropic growth has been proposed. It is found that slow kinetics favor the formation of single-crystalline Au nanorods.

  17. Controllable growth of Prussian blue nanostructures on carboxylic group-functionalized carbon nanofibers and its application for glucose biosensing

    International Nuclear Information System (INIS)

    Wang Li; Ye Yinjian; Zhu Haozhi; Song Yonghai; He Shuijian; Xu Fugang; Hou Haoqing

    2012-01-01

    Glucose detection is very important in biological analysis, clinical diagnosis and the food industry, and especially for the routine monitoring of diabetes. This work presents an electrochemical approach to the detection of glucose based on Prussian blue (PB) nanostructures/carboxylic group-functionalized carbon nanofiber (FCNF) nanocomposites. The hybrid nanocomposites were constructed by growing PB onto the FCNFs. The obtained PB–FCNF nanocomposites were characterized by scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy. The mechanism of formation of PB–FCNF nanocomposites was investigated and is discussed in detail. The PB–FCNF modified glassy carbon electrode (PB–FCNF/GCE) shows good electrocatalysis toward the reduction of H 2 O 2 , a product from the reduction of O 2 followed by glucose oxidase (GOD) catalysis of the oxidation of glucose to gluconic acid. Further immobilizing GOD on the PB–FCNF/GCE, an amperometric glucose biosensor was achieved by monitoring the generated H 2 O 2 under a relatively negative potential. The resulting glucose biosensor exhibited a rapid response of 5 s, a low detection limit of 0.5 μM, a wide linear range of 0.02–12 mM, a high sensitivity of 35.94 μA cm −2 mM −1 , as well as good stability, repeatability and selectivity. The sensor might be promising for practical application. (paper)

  18. Solid state single crystal growth of three-dimensional faceted LaFeAsO crystals

    Science.gov (United States)

    Kappenberger, Rhea; Aswartham, Saicharan; Scaravaggi, Francesco; Blum, Christian G. F.; Sturza, Mihai I.; Wolter, Anja U. B.; Wurmehl, Sabine; Büchner, Bernd

    2018-02-01

    Solid state single crystal growth (SSCG) is a crystal growth technique where crystals are grown from a polycrystalline matrix. Here, we present single crystals of the iron pnictide LaFeAsO grown via SSCG using NaAs as a liquid phase to aid crystallization. The size of the as-grown crystals are up to 2 × 3 × 0.4 mm3. Typical for this method, but very uncommon for crystals of the pnictide superconductors and especially for the oxypnictides, the crystals show pronounced facets caused by considerable growth in c direction. The crystals were characterized regarding their composition, structure, magnetic, and thermodynamic properties. This sets the stage for further measurements for which single crystals are crucial such as any c axis and reciprocal space dependent measurements.

  19. Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

    International Nuclear Information System (INIS)

    Givargizov, E. I.

    2006-01-01

    The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology-fabrication of single-crystal whisker probes for atomic force microscopy

  20. Nanostructures based on quantum dots for application in promising methods of single- and multiphoton imaging and diagnostics

    Science.gov (United States)

    Nabiev, I. R.

    2017-01-01

    Molecules recognizing biomarkers of diseases (monoclonal antibodies (monoABs)) are often too large for biomedical applications, and the conditions that are used to bind them with nanolabels lead to disordered orientation of monoABs with respect to the nanoparticle surface. Extremely small nanoprobes, designed via oriented conjugation of quantum dots (QDs) with single-domain antibodies (sdABs) derived from the immunoglobulin of llama and produced in the E. coli culture, have a hydrodynamic diameter less than 12 nm and contain equally oriented sdAB molecules on the surface of each QD. These nanoprobes exhibit excellent specificity and sensitivity in quantitative determination of a small number of cells expressing biomarkers. In addition, the higher diffusion coefficient of sdABs makes it possible to perform immunohistochemical analysis in bulk tissue, inaccessible for conventional monoABs. The necessary conditions for implementing high-quality immunofluorescence diagnostics are a high specificity of labeling and clear differences between the fluorescence of nanoprobes and the autofluorescence of tissues. Multiphoton micros-copy with excitation in the near-IR spectral range, which is remote from the range of tissue autofluorescence excitation, makes it possible to solve this problem and image deep layers in biological tissues. The two-photon absorption cross sections of CdSe/ZnS QDs conjugated with sdABs exceed the corresponding values for organic fluorophores by several orders of magnitude. These nanoprobes provide clear discrimination between the regions of tumor and normal tissues with a ratio of the sdAB fluorescence to the tissue autofluorescence upon two-photon excitation exceeding that in the case of single-photon excitation by a factor of more than 40. The data obtained indicate that the sdAB-QD conjugates used as labels provide the same, or even better, quality as the "gold standard" of immunohistochemical diagnostics. The developed nanoprobes are expected to

  1. The Way towards Ultrafast Growth of Single-Crystal Graphene on Copper.

    Science.gov (United States)

    Zhang, Zhihong; Xu, Xiaozhi; Qiu, Lu; Wang, Shaoxin; Wu, Tianwei; Ding, Feng; Peng, Hailin; Liu, Kaihui

    2017-09-01

    The exceptional properties of graphene make it a promising candidate in the development of next-generation electronic, optoelectronic, photonic and photovoltaic devices. A holy grail in graphene research is the synthesis of large-sized single-crystal graphene, in which the absence of grain boundaries guarantees its excellent intrinsic properties and high performance in the devices. Nowadays, most attention has been drawn to the suppression of nucleation density by using low feeding gas during the growth process to allow only one nucleus to grow with enough space. However, because the nucleation is a random event and new nuclei are likely to form in the very long growth process, it is difficult to achieve industrial-level wafer-scale or beyond (e.g. 30 cm in diameter) single-crystal graphene. Another possible way to obtain large single-crystal graphene is to realize ultrafast growth, where once a nucleus forms, it grows up so quickly before new nuclei form. Therefore ultrafast growth provides a new direction for the synthesis of large single-crystal graphene, and is also of great significance to realize large-scale production of graphene films (fast growth is more time-efficient and cost-effective), which is likely to accelerate various graphene applications in industry.

  2. Somatic growth in 94 single ventricle children -- comparing systemic right and left ventricle patients

    DEFF Research Database (Denmark)

    Hessel, Trine witzner; Greisen, Gorm; Idorn, Lars

    2013-01-01

    We sought to compare and assess growth in single ventricle children with a systemic right or left ventricle in five time periods: at birth, before neonatal surgery, before the Glenn anastomosis and finally before and after the Fontan operation to 11 years of age.......We sought to compare and assess growth in single ventricle children with a systemic right or left ventricle in five time periods: at birth, before neonatal surgery, before the Glenn anastomosis and finally before and after the Fontan operation to 11 years of age....

  3. Chemical etching of copper foils for single-layer graphene growth by chemical vapor deposition

    Science.gov (United States)

    Yoshihara, Naoki; Noda, Masaru

    2017-10-01

    Chemical etching on copper surface is essential as a pre-treatment for single-layer graphene growth by chemical vapor deposition (CVD). Here, we investigated the effect of chemical etching treatment on copper foils for single-layer graphene CVD growth. The chemical etching conditions, such as the type of chemical etchants and the treatment time, were found to strongly influence the graphene domain size. Moreover, a drastic change in the layer structure of graphene sheets, which was attributed to the surface morphology of the etched copper foil, was confirmed by graphene transmittance and Raman mapping measurements.

  4. Single-step in-situ synthesis and optical properties of ZnSe nanostructured dielectric nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Chirantan; Rahaman Molla, Atiar; Tarafder, Anal; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in [CSIR-Central Glass and Ceramic Research Institute, Glass Science and Technology Section, Glass Division, 196, Raja S. C. Mullick Road, 700032 Kolkata (India); Kr Mishra, Manish; De, Goutam [CSIR-Central Glass and Ceramic Research Institute, Nano-Structured Materials Division, 196, Raja S. C. Mullick Road, 700032 Kolkata (India); Goswami, Madhumita; Kothiyal, G. P. [Glass and Advanced Ceramics Division, Bhaba Atomic Research Centre, Trombay, 400085 Mumbai (India)

    2014-04-07

    This work provides the evidence of visible red photoluminescent light emission from ZnSe nanocrystals (NCs) grown within a dielectric (borosilicate glass) matrix synthesized by a single step in-situ technique for the first time and the NC sizes were controlled by varying only the concentration of ZnSe in glass matrix. The ZnSe NCs were investigated by UV-Vis optical absorption spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM). The sizes of the ZnSe NCs estimated from the TEM images are found to alter in the range of 2–53 nm. Their smaller sizes of the NCs were also calculated by using the optical absorption spectra and the effective mass approximation model. The band gap enlargements both for carrier and exciton confinements were evaluated and found to be changed in the range of 0–1.0 eV. The Raman spectroscopic studies showed blue shifted Raman peaks of ZnSe at 295 and 315 cm{sup −1} indicating phonon confinement effect as well as compressive stress effect on the surface atoms of the NCs. Red photoluminescence in ZnSe-glass nanocomposite reveals a broad multiple-peak structure due to overlapping of emission from NC size related electron-hole recombination (∼707 nm) and emissions from defects to traps, which were formed due to Se and Zn vacancies signifying potential application in photonics.

  5. Mimicking both petal and lotus effects on a single silicon substrate by tuning the wettability of nanostructured surfaces.

    Science.gov (United States)

    Dawood, M K; Zheng, H; Liew, T H; Leong, K C; Foo, Y L; Rajagopalan, R; Khan, S A; Choi, W K

    2011-04-05

    We describe a new method of fabricating large-area, highly scalable, "hybrid" superhydrophobic surfaces on silicon (Si) substrates with tunable, spatially selective adhesion behavior by controlling the morphologies of Si nanowire arrays. Gold (Au) nanoparticles were deposited on Si by glancing-angle deposition, followed by metal-assisted chemical etching of Si to form Si nanowire arrays. These surfaces were chemically modified and rendered hydrophobic by fluorosilane deposition. Au nanoparticles with different size distributions resulted in the synthesis of Si nanowires with very different morphologies (i.e., clumped and straight nanowire surfaces). The difference in nanowire morphology is attributed to capillary force-induced nanocohesion, which is due to the difference in nanowire porosity. The clumped nanowire surface demonstrated the lotus effect, and the straighter nanowires demonstrated the ability to pin water droplets while maintaining large contact angles (i.e., the petal effect). The high contact angles in both cases are explained by invoking the Cassie-Baxter wetting state. The high adhesion behavior of the straight nanowire surface may be explained by a combination of attractive van der Waals forces and capillary adhesion. We demonstrate the spatial patterning of both low- and high-adhesion superhydrophobicity on the same substrate by the simultaneous synthesis of clumped and straight silicon nanowires. The demonstration of hybrid superhydrophobic surfaces with spatially selective, tunable adhesion behavior on single substrates paves the way for future applications in microfluidic channels, substrates for biologically and chemically based analysis and detection where it is necessary to analyze a particular droplet in a defined location on a surface, and as a platform to study in situ chemical mixing and interfacial reactions of liquid pearls.

  6. Percentage of different aluminum doping influence the morphological and optical properties of ZnO nanostructured growth for sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R., E-mail: ruziana12@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia); Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: Zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: hafiz-030@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, Salman A. H., E-mail: dr.salman@alrokayan.com; Khan, Haseeb A., E-mail: khan-haseeb@yahoo.com [Department of Biochemistry, College of Science, King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia)

    2016-07-06

    In this work, Zinc Oxide (ZnO) with different aluminum (Al) doping percentage was synthesis by sol gel immersion method. Al doped ZnO at various doping percentage from 1, 2, 3, 4 and 5. It was found that with different Al percentage influence the morphological and optical properties of ZnO growth. Field Emission Scanning Electron Microscope (FESEM) image showed the use of different Al doping causes the difference in geometry and size of ZnO nanorods growth. Based on UV-Vis spectroscopy, the transmittance at 1% Al doping has the highest spectrum.

  7. Percentage of different aluminum doping influence the morphological and optical properties of ZnO nanostructured growth for sensor application

    International Nuclear Information System (INIS)

    Mohamed, R.; Ismail, A. S.; Khusaimi, Z.; Mamat, M. H.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-01-01

    In this work, Zinc Oxide (ZnO) with different aluminum (Al) doping percentage was synthesis by sol gel immersion method. Al doped ZnO at various doping percentage from 1, 2, 3, 4 and 5. It was found that with different Al percentage influence the morphological and optical properties of ZnO growth. Field Emission Scanning Electron Microscope (FESEM) image showed the use of different Al doping causes the difference in geometry and size of ZnO nanorods growth. Based on UV-Vis spectroscopy, the transmittance at 1% Al doping has the highest spectrum.

  8. Growth and microtopographic study of CuInSe{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Sanjaysinh M.; Chaki, Sunil, E-mail: sunilchaki@yahoo.co.in; Deshpande, M. P. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat - 388120 (India); Tailor, J. P. [Applied Physics Department, S.V.N.I.T., Surat, Gujarat - 395007 (India)

    2016-05-23

    The CuInSe{sub 2} single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe{sub 2} single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe{sub 2} single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

  9. Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Silambarasan, A.; Rajesh, P., E-mail: rajeshp@ssn.edu.in; Ramasamy, P. [Center for Crystal Growth, SSN College of Engineering, Kalavakkam-603110 (India)

    2015-06-24

    The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

  10. Growth Asymmetry, Head Circumference, and Neurodevelopmental Outcomes in Infants with Single Ventricles.

    Science.gov (United States)

    Miller, Thomas A; Zak, Victor; Shrader, Peter; Ravishankar, Chitra; Pemberton, Victoria L; Newburger, Jane W; Shillingford, Amanda J; Dagincourt, Nicholas; Cnota, James F; Lambert, Linda M; Sananes, Renee; Richmond, Marc E; Hsu, Daphne T; Miller, Stephen G; Zyblewski, Sinai C; Williams, Richard V

    2016-01-01

    To assess the variability in asymmetric growth and its association with neurodevelopment in infants with single ventricle (SV). We analyzed weight-for-age z-score minus head circumference-for-age z-score (HCAZ), relative head growth (cm/kg), along with individual growth variables in subjects prospectively enrolled in the Infant Single Ventricle Trial. Associations between growth indices and scores on the Psychomotor Developmental Index (PDI) and Mental Developmental Index (MDI) of the Bayley Scales of Infant Development-II (BSID-II) at 14 months were assessed. Of the 230 subjects enrolled in the Infant Single Ventricle trial, complete growth data and BSID-II scores were available in 168 (73%). Across the cohort, indices of asymmetric growth varied widely at enrollment and before superior cavopulmonary connection (SCPC) surgery. BSID-II scores were not associated with these asymmetry indices. In bivariate analyses, greater pre-SCPC HCAZ correlated with higher MDI (r = 0.21; P = .006) and PDI (r = 0.38; P SCPC with higher PDI (r = 0.15; P = .049). In multivariable modeling, pre-SCPC HCAZ was an independent predictor of PDI (P = .03), but not MDI. In infants with SV, growth asymmetry was not associated with neurodevelopment at 14 months, but pre-SCPC HCAZ was associated with PDI. Asymmetric growth, important in other high-risk infants, is not a brain-sparing adaptation in infants with SV. Clinicaltrials.gov: NCT00113087. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Controllable growth and optical properties of InP and InP/InAs nanostructures on the sidewalls of GaAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xin; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-12-07

    The growth and optical properties of InP and InP/InAs nanostructures on GaAs nanowires are investigated. InP quantum well and quantum dots (QDs) are formed on the sidewalls of GaAs nanowires successively with increasing the deposition time of InP. The GaAs/InP nanowire heterostructure exhibits a type-II band alignment. The wavelength of the InP quantum well is in the range of 857–892 nm at 77 K, which means that the quantum well is nearly fully strained. The InP quantum dot, which has a bow-shaped cross section, exhibits dislocation-free pure zinc blende structure. Stranski-Krastanow InAs quantum dots are subsequently formed on the GaAs/InP nanowire core-shell structure. The InAs quantum dots are distributed over the middle part of the nanowire, indicating that the In atoms contributing to the quantum dots mainly come from the vapor rather than the substrate. The longest emission wavelength obtained from the InAs QDs is 1039 nm at 77 K. The linewidth is as narrow as 46.3 meV, which is much narrower than those on planar InP substrates and wurtzite InP nanowires, suggesting high-crystal-quality, phase-purity, and size-uniformity of quantum dots.

  12. Controllable growth and optical properties of InP and InP/InAs nanostructures on the sidewalls of GaAs nanowires

    International Nuclear Information System (INIS)

    Yan, Xin; Zhang, Xia; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin

    2014-01-01

    The growth and optical properties of InP and InP/InAs nanostructures on GaAs nanowires are investigated. InP quantum well and quantum dots (QDs) are formed on the sidewalls of GaAs nanowires successively with increasing the deposition time of InP. The GaAs/InP nanowire heterostructure exhibits a type-II band alignment. The wavelength of the InP quantum well is in the range of 857–892 nm at 77 K, which means that the quantum well is nearly fully strained. The InP quantum dot, which has a bow-shaped cross section, exhibits dislocation-free pure zinc blende structure. Stranski-Krastanow InAs quantum dots are subsequently formed on the GaAs/InP nanowire core-shell structure. The InAs quantum dots are distributed over the middle part of the nanowire, indicating that the In atoms contributing to the quantum dots mainly come from the vapor rather than the substrate. The longest emission wavelength obtained from the InAs QDs is 1039 nm at 77 K. The linewidth is as narrow as 46.3 meV, which is much narrower than those on planar InP substrates and wurtzite InP nanowires, suggesting high-crystal-quality, phase-purity, and size-uniformity of quantum dots

  13. Vortices and nanostructured superconductors

    CERN Document Server

    2017-01-01

    This book provides expert coverage of modern and novel aspects of the study of vortex matter, dynamics, and pinning in nanostructured and multi-component superconductors. Vortex matter in superconducting materials is a field of enormous beauty and intellectual challenge, which began with the theoretical prediction of vortices by A. Abrikosov (Nobel Laureate). Vortices, vortex dynamics, and pinning are key features in many of today’s human endeavors: from the huge superconducting accelerating magnets and detectors at the Large Hadron Collider at CERN, which opened new windows of knowledge on the universe, to the tiny superconducting transceivers using Rapid Single Flux Quanta, which have opened a revolutionary means of communication. In recent years, two new features have added to the intrinsic beauty and complexity of the subject: nanostructured/nanoengineered superconductors, and the discovery of a range of new materials showing multi-component (multi-gap) superconductivity. In this book, leading researche...

  14. Investigation on the bulk growth of α-LiIO 3 single crystals and the ...

    Indian Academy of Sciences (India)

    2017-07-26

    Jul 26, 2017 ... Herein, we investigate to grow bulk size good quality crystals of α-LiIO3 based on the observed problems during its crystallization process. A systematic investigation was carried out to find the effect of pH on solubility, crystal growth, structural, surface and laser damage properties of α-LiIO3 single crystals.

  15. Single-cell screening of photosynthetic growth and lactate production by cyanobacteria

    NARCIS (Netherlands)

    Hammar, P.; Angermayr, S.A.; Sjostrom, S.L.; van der Meer, J.; Hellingwerf, K.J.; Hudson, E.P.; Joensson, H.N.

    2015-01-01

    BACKGROUND: Photosynthetic cyanobacteria are attractive for a range of biotechnological applications including biofuel production. However, due to slow growth, screening of mutant libraries using microtiter plates is not feasible. RESULTS: We present a method for high-throughput, single-cell

  16. Fatigue de-bond growth in adhesively bonded single lap joints

    Indian Academy of Sciences (India)

    life of adhesively bonded joints under both constant and variable amplitude fatigue loads. Keywords. ... This involves three stages such as crack initiation, crack propagation and final fail- ure. During crack ... growth rate curve was determined with this data and used for fatigue life prediction of single-lap joint specimens.

  17. Ultrafast growth of single-crystal graphene assisted by a continuous oxygen supply

    Science.gov (United States)

    Xu, Xiaozhi; Zhang, Zhihong; Qiu, Lu; Zhuang, Jianing; Zhang, Liang; Wang, Huan; Liao, Chongnan; Song, Huading; Qiao, Ruixi; Gao, Peng; Hu, Zonghai; Liao, Lei; Liao, Zhimin; Yu, Dapeng; Wang, Enge; Ding, Feng; Peng, Hailin; Liu, Kaihui

    2016-11-01

    Graphene has a range of unique physical properties and could be of use in the development of a variety of electronic, photonic and photovoltaic devices. For most applications, large-area high-quality graphene films are required and chemical vapour deposition (CVD) synthesis of graphene on copper surfaces has been of particular interest due to its simplicity and cost effectiveness. However, the rates of growth for graphene by CVD on copper are less than 0.4 μm s-1, and therefore the synthesis of large, single-crystal graphene domains takes at least a few hours. Here, we show that single-crystal graphene can be grown on copper foils with a growth rate of 60 μm s-1. Our high growth rate is achieved by placing the copper foil above an oxide substrate with a gap of ∼15 μm between them. The oxide substrate provides a continuous supply of oxygen to the surface of the copper catalyst during the CVD growth, which significantly lowers the energy barrier to the decomposition of the carbon feedstock and increases the growth rate. With this approach, we are able to grow single-crystal graphene domains with a lateral size of 0.3 mm in just 5 s.

  18. Single vacancy defects diffusion at the initial stage of graphene growth: A first-principles study

    International Nuclear Information System (INIS)

    Du, H.B.; Jia, Y.; Sun, Q.; Guo, Z.X.

    2015-01-01

    The migration of a single vacancy (SV) defect in graphene fragment (GF) has been investigated by density functional theory (DFT). The results revealed that a single vacancy defect is easy to migrate to the GF edge. The interaction between an SV and a five-numbered ring at the edge results in two neighboring five-membered rings finally, while the interaction between an SV and a seven-membered ring defect at the edge of the GF leads to a five-numbered ring and a neighbor seven-numbered ring. Our findings shed light upon understanding of the growth process of the graphene grain boundary. - Highlights: • The migration of single vacancy in graphene fragment. • The interaction between single vacancy and five- or seven-membered ring. • The possible reason why it is difficult to find single vacancy inside graphene

  19. Raman spectral dynamics of single cells in the early stages of growth factor stimulation.

    Science.gov (United States)

    Takanezawa, Sota; Morita, Shin-ichi; Ozaki, Yukihiro; Sako, Yasushi

    2015-05-05

    Cell fates change dynamically in response to various extracellular signals, including growth factors that stimulate differentiation and proliferation. The processes underlying cell-fate decisions are complex and often include large cell-to-cell variations, even within a clonal population in the same environment. To understand the origins of these cell-to-cell variations, we must detect the internal dynamics of single cells that reflect their changing chemical milieu. In this study, we used the Raman spectra of single cells to trace their internal dynamics during the early stages of growth factor stimulation. This method allows nondestructive and inclusive time-series analyses of chemical compositions of the same single cells. Applying a Gaussian mixture model to the major principal components of the single-cell Raman spectra, we detected the dynamics of the chemical states in MCF-7 cancer-derived cells in the absence and presence of differentiation and proliferation factors. The dynamics displayed characteristic variations according to the functions of the growth factors. In the differentiation pathway, the chemical composition changed directionally between multiple states, including both reversible and irreversible state transitions. In contrast, in the proliferation pathway, the chemical composition was homogenized into a single state. The differentiation factor also stimulated fluctuations in the chemical composition, whereas the proliferation factor did not. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. On the design and fabrication of nanostructures and devices

    Science.gov (United States)

    Wei, Wei

    Nanotechnology is emerging into a new frontier in science and technology with potential impact on every aspect of human life. One of the major breakthroughs in today's nanotechnology is the discovery and preparation of new classes of nanomaterials and nanostructures. A large number of nanomaterials and nanostructures are synthesized and characterized with either new or profoundly enhanced properties or phenomena. However, there are several major challenges ahead need to be overcome before any substantial benefits can be brought to the market. One of the challenges that we need to address today is how to effectively integrate useful nanomaterials and nanostrucrures into functional devices and systems. Our mother nature gives us a classic example of how living organisms are built. Starting from a single cell, through its division and growth, it can self-assemble and become functional tissues and organs. Similar self-assemble approach has been adopted as a nano-fabrication technique to assemble nanomaterials and nanostructures into functional nanodevices. This technique has advantages of high precision and nanometer scale resolution. However, it requires a lot of effort to construct a single device and since the properties of individual nanostructures can be different, the fabricated devices may have different properties. In this dissertation, we design and fabricate nanostructures and devices using novel microfabrication techniques. In the first part of the dissertation, the design and fabrication of a variety of nanostructures, such as metal nanowires array, polymer nanowells, and nanostructured surfaces are discussed. In the second part, carbon nanotubes as a novel material has been explored as an example to demonstrate the integration of nanomaterials with novel microfabrication techniques to form a functional device. First, a resistive heating technique is developed to grow carbon nanotubes in localized regions, such as a nichrome heating coil. Then, MEMS micro

  1. SrZnO nanostructures grown on templated Al2O3 substrates by pulsed laser deposition

    Science.gov (United States)

    Labis, Joselito P.; Alanazi, Anwar Q.; Albrithen, Hamad A.; El-Toni, Ahmed Mohamed; Hezam, Mahmoud; Elafifi, Hussein Elsayed; Abaza, Osama M.

    2017-09-01

    The parameters of pulsed laser deposition (PLD) have been optimized to design different nanostructures of Strontium-alloyed zinc oxide (SrZnO). In this work, SrZnO nanostructures are grown on Al2O3 substrates via two-step templating/seeding approach. In the temperature range between 300 - 750 oC and O2 background pressures between 0.01 and 10 Torr, the growth conditions have been tailored to grow unique pointed leaf-like- and pitted olive-like nanostructures. Prior to the growth of the nanostructures, a thin SrZnO layer that serves as seed layer/template is first deposited on the Al2O3 substrates at ˜300oC and background oxygen pressure of 10 mTorr. The optical properties of the nanostructures were examined by UV/Vis spectroscopy and photoluminescence (PL), while the structures/morphologies were examined by SEM, TEM, and XRD. The alloyed SrZnO nanostructures, grown by ablating ZnO targets with 5, 10, 25% SrO contents, have in common a single-crystal hexagonal nanostructure with (0002) preferential orientation and have shown remarkable changes in the morphological and optical properties of the materials. To date, this is the only reported work on optimization of laser ablation parameters to design novel SrZnO nanostructures in the 5-25% alloying range, as most related Sr-doped ZnO studies were done below 7% doping. Although the physical properties of ZnO are modified via Sr doping, the mechanism remains unclear. The PLD-grown SrZnO nanostructures were directly grown onto the Al2O3 substrates; thus making these nanomaterials very promising for potential applications in biosensors, love-wave filters, solar cells, and ultrasonic oscillators.

  2. SrZnO nanostructures grown on templated Al2O3 substrates by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    Joselito P. Labis

    2017-09-01

    Full Text Available The parameters of pulsed laser deposition (PLD have been optimized to design different nanostructures of Strontium-alloyed zinc oxide (SrZnO. In this work, SrZnO nanostructures are grown on Al2O3 substrates via two-step templating/seeding approach. In the temperature range between 300 - 750 oC and O2 background pressures between 0.01 and 10 Torr, the growth conditions have been tailored to grow unique pointed leaf-like- and pitted olive-like nanostructures. Prior to the growth of the nanostructures, a thin SrZnO layer that serves as seed layer/template is first deposited on the Al2O3 substrates at ∼300oC and background oxygen pressure of 10 mTorr. The optical properties of the nanostructures were examined by UV/Vis spectroscopy and photoluminescence (PL, while the structures/morphologies were examined by SEM, TEM, and XRD. The alloyed SrZnO nanostructures, grown by ablating ZnO targets with 5, 10, 25% SrO contents, have in common a single-crystal hexagonal nanostructure with (0002 preferential orientation and have shown remarkable changes in the morphological and optical properties of the materials. To date, this is the only reported work on optimization of laser ablation parameters to design novel SrZnO nanostructures in the 5-25% alloying range, as most related Sr-doped ZnO studies were done below 7% doping. Although the physical properties of ZnO are modified via Sr doping, the mechanism remains unclear. The PLD-grown SrZnO nanostructures were directly grown onto the Al2O3 substrates; thus making these nanomaterials very promising for potential applications in biosensors, love-wave filters, solar cells, and ultrasonic oscillators.

  3. Continuous growth of single-wall carbon nanotubes using chemical vapor deposition

    Science.gov (United States)

    Grigorian, Leonid [Raymond, OH; Hornyak, Louis [Evergreen, CO; Dillon, Anne C [Boulder, CO; Heben, Michael J [Denver, CO

    2008-10-07

    The invention relates to a chemical vapor deposition process for the continuous growth of a carbon single-wall nanotube where a carbon-containing gas composition is contacted with a porous membrane and decomposed in the presence of a catalyst to grow single-wall carbon nanotube material. A pressure differential exists across the porous membrane such that the pressure on one side of the membrane is less than that on the other side of the membrane. The single-wall carbon nanotube growth may occur predominately on the low-pressure side of the membrane or, in a different embodiment of the invention, may occur predominately in between the catalyst and the membrane. The invention also relates to an apparatus used with the carbon vapor deposition process.

  4. Growth and Characteristics of Bulk Single Crystals Grown from Solution on Earth and in Microgravity

    Science.gov (United States)

    Aggarwal, M. D.; Batra, A. K.; Lal, R. B.; Penn, Benjamin G.; Frazier, Donald O.

    2011-01-01

    The growth of crystals has been of interest to physicists and engineers for a long time because of their unique properties. Single crystals are utilized in such diverse applications as pharmaceuticals, computers, infrared detectors, frequency measurements, piezoelectric devices, a variety of high technology devices and sensors. Solution crystal growth is one of the important techniques to grow a variety of crystals when the material decomposes at the melting point and a suitable solvent is available to make a saturated solution at a desired temperature. In this chapter an attempt is made to give some fundamentals of growing crystals from solution including improved designs of various crystallizers. Since the same solution crystal growth technique could not be used in microgravity, authors had proposed a new cooled sting technique to grow crystals in space. Authors? experiences of conducting two space shuttle experiments relating to solution crystal growth are also detailed in this work. The complexity of these solution growth experiments to grow crystals in space are discussed. These happen to be some of the early experiments performed in space, and various lessons learned are described. A brief discussion of protein crystal growth that also shares basic principles of solution growth technique is given along with some flight hardware information for its growth in microgravity.

  5. Unidirectional growth and characterization of L-arginine monohydrochloride monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India); Babu, R. Ramesh, E-mail: rampap2k@yahoo.co.in [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India); Bhagavannarayana, G. [Materials Characterization Division, National Physical Laboratory, New Delhi 110 012 (India); Ramamurthi, K. [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India)

    2011-10-17

    Highlights: {yields} L-Arginine monohydrochloride monohydrate (LAHCl) single crystal was grown successfully by unidirectional solution growth method for the first time. {yields} High crystalline perfection was observed for UDS grown crystal compared to CS grown crystal. {yields} The optical transparency and mechanical stability are high for UDS grown LAHCl single crystal. {yields} Optical birefringence measurement on this material. {yields} The piezoelectric resonance frequencies observation - first time observation on this material. - Abstract: L-Arginine monohydrochloride monohydrate (LAHCl) single crystals were grown successfully by conventional and unidirectional solution growth methods. The crystalline perfection of grown crystals was analyzed by high-resolution X-ray diffraction. The linear optical transmittance, mechanical stability of conventional and unidirectional grown LAHCl single crystals were analyzed and compared along (0 0 1) plane. The refractive index and birefringence of LAHCl single crystals were also measured using He-Ne laser source. From the dielectric studies, piezoelectric resonance frequencies were observed in kHz frequency range for both conventional and unidirectional grown LAHCl single crystals along (0 0 1) plane.

  6. Nanostructure Neutron Converter Layer Development

    Science.gov (United States)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  7. Single-crystal growth of Group IVB and VB carbides by the floating-zone method

    International Nuclear Information System (INIS)

    Finch, C.B.; Chang, Y.K.; Abraham, M.M.

    1989-02-01

    The floating-zone method for the growth of Group IVB and VB carbides is described and reviewed. We have systematically investigated the technique and confirmed the growth of large single crystals of TiC/sub 0.95/, ZrC/sub 0.93/, ZrC/sub 0.98/, VC/sub 0.80/, NbC/sub 0.95/, TaC/sub 0.89/. Optimal growth conditions were in the 0.5-2.0 cm/h range under 8-12 atm helium. Good crystal growth results were achieved with hot-pressed starting rods of 90-95% density, using a ''double pancake'' induction coil and a 200-kHz/100- kW rf power supply. 36 refs., 5 figs., 3 tabs

  8. Prepubertal growth and single nucleotide polymorphism analysis of the growth hormone gene of low birth weight Holstein calves

    OpenAIRE

    Ro, Younghye; Choi, Woojae; Kim, Hoyung; Jang, Hojin; Lee, Hoseon; Lee, Yoonseok; Kim, Danil

    2018-01-01

    Holstein calves weighing less than 20 kg at birth have been noted in Korea. Due to insufficient information, we raised small calves with age-matched normal birth weight Holstein calves and determined body weights before puberty. In addition, 3 single nucleotide polymorphisms (SNPs) of the growth hormone (GH) gene were analyzed. Up to 10 months of age, low birth weight calves were smaller than normal weight calves. In exon 5 of the GH gene, SNP genotype variation was detected in some small cal...

  9. Synthesis of nanostructures in nanowires using sequential catalyst reactions

    Science.gov (United States)

    Panciera, F.; Chou, Y.-C.; Reuter, M.C.; Zakharov, D.; Stach, E.A.; Hofmann, S.; Ross, F.M.

    2016-01-01

    Nanowire growth by the vapor-liquid-solid process enables a high level of control over nanowire composition, diameter, growth direction, branching and kinking, periodic twinning, and crystal structure. The tremendous impact of VLS-grown nanowires is due to this structural versatility, generating applications ranging from solid state lighting and single photon sources to thermoelectric devices. Here we show that the morphology of these nanostructures can be further tailored by using the liquid droplets that catalyze nanowire growth as a “mixing bowl”, in which growth materials are sequentially supplied to nucleate new phases. Growing within the liquid, these phases adopt the shape of faceted nanocrystals that are then incorporated into the nanowires by further growth. We demonstrate this concept by epitaxially incorporating metal silicide nanocrystals into Si nanowires with defect-free interfaces, and discuss how this process can be generalized to create complex nanowire-based heterostructures. PMID:26168344

  10. Tree Height Growth Measurement with Single-Scan Airborne, Static Terrestrial and Mobile Laser Scanning

    Directory of Open Access Journals (Sweden)

    Yi Lin

    2012-09-01

    Full Text Available This study explores the feasibility of applying single-scan airborne, static terrestrial and mobile laser scanning for improving the accuracy of tree height growth measurement. Specifically, compared to the traditional works on forest growth inventory with airborne laser scanning, two issues are regarded: “Can the new technique characterize the height growth for each individual tree?” and “Can this technique refine the minimum growth-discernable temporal interval further?” To solve these two puzzles, the sampling principles of the three laser scanning modes were first examined, and their error sources against the task of tree-top capturing were also analyzed. Next, the three-year growths of 58 Nordic maple trees (Crimson King for test were intermittently surveyed with one type of laser scanning each time and then analyzed by statistics. The evaluations show that the height growth of each individual tree still cannot be reliably characterized even by single-scan terrestrial laser scanning, and statistical analysis is necessary in this scenario. After Gaussian regression, it is found that the minimum temporal interval with distinguishable tree height growths can be refined into one month based on terrestrial laser scanning, far better than the two years deduced in the previous works based on airborne laser scanning. The associated mean growth was detected to be about 0.12 m. Moreover, the parameter of tree height generally under-estimated by airborne and even mobile laser scanning can be relatively revised by means of introducing static terrestrial laser scanning data. Overall, the effectiveness of the proposed technique is primarily validated.

  11. Ignition and growth modeling of detonation reaction zone experiments on single crystals of PETN and HMX

    Science.gov (United States)

    White, Bradley W.; Tarver, Craig M.

    2017-01-01

    It has long been known that detonating single crystals of solid explosives have much larger failure diameters than those of heterogeneous charges of the same explosive pressed or cast to 98 - 99% theoretical maximum density (TMD). In 1957, Holland et al. demonstrated that PETN single crystals have failure diameters of about 8 mm, whereas heterogeneous PETN charges have failure diameters of less than 0.5 mm. Recently, Fedorov et al. quantitatively determined nanosecond time resolved detonation reaction zone profiles of single crystals of PETN and HMX by measuring the interface particle velocity histories of the detonating crystals and LiF windows using a PDV system. The measured reaction zone time durations for PETN and HMX single crystal detonations were approximately 100 and 260 nanoseconds, respectively. These experiments provided the necessary data to develop Ignition and Growth (I&G) reactive flow model parameters for the single crystal detonation reaction zones. Using these parameters, the calculated unconfined failure diameter of a PETN single crystal was 7.5 +/- 0.5 mm, close to the 8 mm experimental value. The calculated failure diameter of an unconfined HMX single crystal was 15 +/- 1 mm. The unconfined failure diameter of an HMX single crystal has not yet been determined precisely, but Fedorov et al. detonated 14 mm diameter crystals confined by detonating a HMX-based plastic bonded explosive (PBX) without initially overdriving the HMX crystals.

  12. Sublimation growth of nonpolar AlN single crystals and defect characterization

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Issei; Arakawa, Satoshi; Tanizaki, Keisuke; Miyanaga, Michimasa; Yamamoto, Yoshiyuki [Sumitomo Electric Industries, Ltd., 1-1-1 Koyakita, Itami, Hyogo 664-0016 (Japan)

    2010-07-15

    Sublimation growth of nonpolar AlN single crystals was investigated. The crystals were prepared in two methods: By slicing along the m -plane from c -plane-grown thick crystals, and by heteroepitaxial growth on m -plane SiC substrates. Defects of the crystals were observed by high-resolution transmission electron microscope. Dislocation density in AlN/SiC (0001) decreased significantly at about 1.5 {mu}m above the interface, while stacking faults initiated from the interface toward the growth surface in AlN/SiC (1-100). With increasing crystal thickness, the dislocation density decreases up to 5 x 10{sup 4}/cm{sup 2} at the thickness of 10 mm. In the AlN single crystal grown on SiC (0001), it is noteworthy that the dislocations are localized around the AlN/SiC interface and that far fewer dislocations occur near the growth surface. High-crystallinity AlN thick single crystals could be grown on SiC (0001) substrates. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. The Impact of Single Amino Acids on Growth and Volatile Aroma Production by Saccharomyces cerevisiae Strains

    Directory of Open Access Journals (Sweden)

    Samantha Fairbairn

    2017-12-01

    Full Text Available Nitrogen availability and utilization by Saccharomyces cerevisiae significantly influence fermentation kinetics and the production of volatile compounds important for wine aroma. Amino acids are the most important nitrogen source and have been classified based on how well they support growth. This study evaluated the effect of single amino acids on growth kinetics and major volatile production of two phenotypically different commercial wine yeast strains in synthetic grape must. Four growth parameters, lag phase, maximum growth rate, total biomass formation and time to complete fermentation were evaluated. In contrast with previous findings, in fermentative conditions, phenylalanine and valine supported growth well and asparagine supported it poorly. The four parameters showed good correlations for most amino acid treatments, with some notable exceptions. Single amino acid treatments resulted in the predictable production of aromatic compounds, with a linear correlation between amino acid concentration and the concentration of aromatic compounds that are directly derived from these amino acids. With the increased complexity of nitrogen sources, linear correlations were lost and aroma production became unpredictable. However, even in complex medium minor changes in amino acid concentration continued to directly impact the formation of aromatic compounds, suggesting that the relative concentration of individual amino acids remains a predictor of aromatic outputs, independently of the complexity of metabolic interactions between carbon and nitrogen metabolism and between amino acid degradation and utilization pathways.

  14. Synthesis and growth of single crystals of PrCl3

    International Nuclear Information System (INIS)

    Pei, Jen Shieh.

    1984-01-01

    An efficient method for growth of high optical quality single crystals of PrCl 3 . The method consists in careful drying of the hydrated chloride, PrCl 3 . 7H 2 O, with a protective atmosphere of anhydrous HCl and Ar. A subsequent growth was done by the zone melting technique. The hydrated chloride had prepared from dissolution of the oxide Pr 6 O 11 in hydrochloric acid. The grown crystals had characterized fluorescence and x-ray diffraction measurements. (Author) [pt

  15. Visualizing the growth dynamics of individual single-wall carbon nanotubes

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Zhang, Lili; He, Maoshuai

    In order to meet the increasing demand of faster and more flexible electronics and optical devices and at the same time decrease the use of the critical metals, carbon based devices are in fast development. Single walled carbon nanotube (SWCNT) based electronics is a way of addressing...... around the studied sample at elevated temperature gives a unique way of monitoring gas-solid interactions such as CNT growth. Here we show the direct experimental evidence on the growth dynamics of SW-CNTs from Co/MgO catalysts using CO as carbon source inside the environmental TEM. The evolution...

  16. Many-particle theory of optical properties in low-dimensional nanostructures. Dynamics in single-walled carbon nanotubes and semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Malic, Ermin

    2008-09-02

    This work focuses on the theoretical investigation of optical properties of low-dimensional nanostructures, specifically single-walled carbon nanotubes (CNTs) and self-assembled InAs/GaAs quantum dots (QDs). The density-matrix formalism is applied to explain recent experimental results and to give insight into the underlying physics. A microscopic calculation of the absorption coefficient and the Rayleigh scattering cross section is performed by a novel approach combining the density-matrix formalism with the tight-binding wave functions. The calculated spectra of metallic nanotubes show a double-peaked structure resulting from the trigonal warping effect. The intensity ratios of the four lowest-lying transitions in both absorption and Rayleigh spectra can be explained by the different behavior of the optical matrix elements along the high-symmetry lines K-{gamma} and K-M. The Rayleigh line shape is predicted to be asymmetric, with an enhanced cross section for lower photon energies arising from non-resonant contributions of the optical susceptibility. Furthermore, the Coulomb interaction is shown to be maximal when the momentum transfer is low. For intersubband processes with a perpendicular momentum transfer, the coupling strength is reduced to less than 5%. The chirality and diameter dependence of the excitonic binding energy and the transition frequency are presented in Kataura plots. Furthermore, the influence of the surrounding environment on the optical properties of CNTs is investigated. Extending the confinement to all three spatial dimensions, semiconductor Bloch equation are derived to describe the dynamics in QD semiconductor lasers and amplifiers. A detailed microscopic analysis of the nonlinear turn-on dynamics of electrically pumped InAs/GaAs QD lasers is performed, showing the generation of relaxation oscillations on a nanosecond time scale in both the photon and charge carrier density. The theory predicts a strong damping of relaxation oscillations

  17. Many-particle theory of optical properties in low-dimensional nanostructures. Dynamics in single-walled carbon nanotubes and semiconductor quantum dots

    International Nuclear Information System (INIS)

    Malic, Ermin

    2008-01-01

    This work focuses on the theoretical investigation of optical properties of low-dimensional nanostructures, specifically single-walled carbon nanotubes (CNTs) and self-assembled InAs/GaAs quantum dots (QDs). The density-matrix formalism is applied to explain recent experimental results and to give insight into the underlying physics. A microscopic calculation of the absorption coefficient and the Rayleigh scattering cross section is performed by a novel approach combining the density-matrix formalism with the tight-binding wave functions. The calculated spectra of metallic nanotubes show a double-peaked structure resulting from the trigonal warping effect. The intensity ratios of the four lowest-lying transitions in both absorption and Rayleigh spectra can be explained by the different behavior of the optical matrix elements along the high-symmetry lines K-Γ and K-M. The Rayleigh line shape is predicted to be asymmetric, with an enhanced cross section for lower photon energies arising from non-resonant contributions of the optical susceptibility. Furthermore, the Coulomb interaction is shown to be maximal when the momentum transfer is low. For intersubband processes with a perpendicular momentum transfer, the coupling strength is reduced to less than 5%. The chirality and diameter dependence of the excitonic binding energy and the transition frequency are presented in Kataura plots. Furthermore, the influence of the surrounding environment on the optical properties of CNTs is investigated. Extending the confinement to all three spatial dimensions, semiconductor Bloch equation are derived to describe the dynamics in QD semiconductor lasers and amplifiers. A detailed microscopic analysis of the nonlinear turn-on dynamics of electrically pumped InAs/GaAs QD lasers is performed, showing the generation of relaxation oscillations on a nanosecond time scale in both the photon and charge carrier density. The theory predicts a strong damping of relaxation oscillations

  18. Growth and characterization of 2-methylquinolinium L-malate single crystal

    Science.gov (United States)

    Bharathi, M. Divya; Ahila, G.; Mohana, J.; Anbalagan, G.

    2017-05-01

    An organic nonlinear optical single crystal, 2-methylquinolinium L-malate (MLM) was grown from ethanol solvent using slow evaporation solution growth technique. The single crystal X-ray diffraction studies confirmed that the crystal belongs to the monoclinic system with the non-centrosymmetric space group P21. The crystal is transparent in the entire visible region. The second harmonic generation efficiency of the grown crystal has been obtained by the Kurtz-Perry powder technique. The laser damage threshold value 5.58 GW/cm2 indicates that this crystal can be used for high-power laser applications.

  19. One-dimensional Si-in-Si(001) template for single-atom wire growth

    Science.gov (United States)

    Owen, J. H. G.; Bianco, F.; Köster, S. A.; Mazur, D.; Bowler, D. R.; Renner, Ch.

    2010-08-01

    Single atom metallic wires of arbitrary length are of immense technological and scientific interest. We present atomic-resolution scanning tunneling microscope data of a silicon-only template, which modeling predicts to enable the self-organized growth of isolated micrometer long surface and subsurface single-atom chains. It consists of a one-dimensional, defect-free Si reconstruction four dimers wide—the Haiku core—formed by hydrogenation of self-assembled Bi-nanolines on Si(001) terraces, independent of any step edges. We discuss the potential of this Si-in-Si template as an appealing alternative to vicinal surfaces for nanoscale patterning.

  20. Method for single crystal growth of photovoltaic perovskite material and devices

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinsong; Dong, Qingfeng

    2017-11-07

    Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container, also including at least one small perovskite single crystal, and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows, in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate. For example, a top portion of the substrate external to the solution may be cooled.

  1. Government Should Subsidize, Not Tax, Marriage: Social Policies Have Influenced the Rate of Growth in Single-Parent Families

    Science.gov (United States)

    Peterson, Paul E.

    2015-01-01

    Based upon reflections from the Moynihan report of 1965, this author notes that the root causes of the growth in single-parent families have yet to be well identified, making it difficult to figure out where to go next. However, from 1965 onward, social policies have influenced the rate of growth in single-parent families. What is needed is a…

  2. Nanopattern formation using localized plasma for growth of single-standing carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Javadi, Mohammad; Abdi, Yaser, E-mail: y.abdi@ut.ac.ir [University of Tehran, Nanophysics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

    2017-01-15

    We report a novel method for formation of self-organized single-standing carbon nanotubes by customizing a plasma-based process. The growth of carbon nanotubes by plasma-enhanced chemical vapor deposition provides suitable grounds to utilize plasma–solid interactions for nanopatterning. The bulk plasma is utilized to fabricate carbon nanotubes on the prepatterned Ni catalyst which in turn can confine the plasma to the growth region. The plasma localization leads to a dielectrophoretic force exerted on Ni atoms and can be engineered in order to grow a specific pattern of self-organized single-standing carbon nanotubes. Numerical simulations based on the plasma localization and dielectrophoretic force confirmed the experimental results. This method provides a simple and cost-effective approach to obtain nanopatterned arrays of carbon nanotubes which can be used for fabrication of photonic and phononic crystals, self-gated field emission-based transistors and displays.

  3. Nonlinear growth of a single neoclassical MHD tearing mode in a tokamak

    International Nuclear Information System (INIS)

    Qu, W.X.; Callen, J.D.

    1985-10-01

    The nonlinear evolution equation for the growth of a single neoclassical MHD tearing mode is derived from the usual resistive MHD equations with neoclassical effects included. For the case Δ' > 0 where the usual resistive MHD modes are unstable, in nonlinear neoclassical MHD there is an intermediate time regime in which the island width w grows only as t/sup 1/2/. However, eventually the neoclassical MHD tearing modes are found to enter the usual resistive MHD Rutherford regime where w infinity t. Physically, the neoclassical MHD bootstrap current effects modify the linear and early nonlinear growth of tearing modes. However, eventually the magnetic islands flatten the pressure gradient within the island to remove these effects and return, at long times, to the usual quasilinear picture for the nonlinear evolution of a single resistive MHD tearing mode

  4. Single-cell screening of photosynthetic growth and lactate production by cyanobacteria

    DEFF Research Database (Denmark)

    Hammar, Petter; Angermayr, S. Andreas; Sjostrom, Staffan L.

    2015-01-01

    Background: Photosynthetic cyanobacteria are attractive for a range of biotechnological applications including biofuel production. However, due to slow growth, screening of mutant libraries using microtiter plates is not feasible.Results: We present a method for high-throughput, single......-cell analysis and sorting of genetically engineered l-lactate-producing strains of Synechocystis sp. PCC6803. A microfluidic device is used to encapsulate single cells in picoliter droplets, assay the droplets for L-lactate production, and sort strains with high productivity. We demonstrate the separation...... of low- and high-producing reference strains, as well as enrichment of a more productive L-lactate-synthesizing population after UV-induced mutagenesis. The droplet platform also revealed population heterogeneity in photosynthetic growth and lactate production, as well as the presence of metabolically...

  5. Growth of methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals

    Science.gov (United States)

    Perigaud, A.; Nicolau, Y. F.

    1986-12-01

    Methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals, 1 cm in diameter and 7 cm in length have been grown by a travelling-heater-Bridgman method in polyethylene tubes introduced into glass ampoules, at a growth rate of 1.5-6 mm/day. The starting material was synthesised and purified by recrystallization from methanol and by vacuum evaporation to a purity of 99.994%. The period of growth, and hence the length of the crystal, is limited due to melt decomposition and polycondensation. The b-axis of the crystals is always oriented at about 72° to the ampoule axis. Good quality single crystals have been obtained giving a FWHM of the Cu Kα (040) rocking curve of about 1'.

  6. Production of fullerenic nanostructures in flames

    Science.gov (United States)

    Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das

    1999-01-01

    A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

  7. Combined effect of viscosity and vorticity on single mode Rayleigh-Taylor instability bubble growth

    International Nuclear Information System (INIS)

    Banerjee, Rahul; Mandal, Labakanta; Roy, S.; Khan, M.; Gupta, M. R.

    2011-01-01

    The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh-Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it.

  8. Single-chain vascular endothelial growth factor variant with antagonist activity

    DEFF Research Database (Denmark)

    Boesen, Thomas P; Soni, Bobby; Schwartz, Thue W

    2002-01-01

    receptor molecules and inducing dimerization. By mixing two vascular endothelial growth factor monomers, each with different substitutions, heterodimers with only one active receptor binding site have previously been prepared. These heterodimers bind the receptor molecule but are unable to induce...... dimerization and activation. However, preparation of heterodimers is cumbersome, involving separate expression of different monomers, refolding the mixture, and separating heterodimers from homodimers. Here we show that a fully functional ligand can efficiently be expressed as a single protein chain containing...

  9. Growth of Ce-Doped LSO Single Crystals by Stockbarger-Bridgman Modified Crystallization Method

    International Nuclear Information System (INIS)

    Namtalishvili, M.; Sanadze, T.; Basharuli, N.; Magalashvili, P.; Mikaberidze, A.; Razmadze, Z.; Gabeskiria, M.

    2006-01-01

    The modified Stockbarger-Bridgman method was suggested for the growth of optically perfect LSO:Ce single crystals. Our investigations have shown that the most perfect crystals are grown by by the horizontally directed crystallization. In this case the elements of directional crystallyzation are combined with the zone melting. Crystallization is carried out in the conditions of sufficiently developed mirror of meltin. As a result in this case the chemical purity of grown crystals increases. (author)

  10. Influence of vacuum degree on growth of Bi2Te3 single crystal

    Science.gov (United States)

    Tang, Yan-Kun; Zhao, Wen-Juan; Zhu, Hua-Qiang; Huang, Yong-Chao; Cao, Wei-Wei; Yang, Qian; Yao, Xiao-Yan; Zhai, Ya; Dong, Shuai

    2015-07-01

    Bi2Te3 single crystals were prepared by the solid-state reaction method. The effect of the vacuum on the growth of Bi2Te3 single crystals was studied with varying the oxygen content by controlling the air pressure in the silica tube. High quality Bi2Te3 single crystals have been obtained and there is no influence on the growth by an extremely small amount of oxygen in a high vacuum at 1.0 × 10-3 Pa. As the air pressure is increased at 1.0 × 10-2 Pa, oxygen only mainly impacts on the growth of the surface for the prepared samples. Micron-sized rod-like structure and flower-like clusters are observed on the surface. For the samples prepared at 1.0 × 10-1 Pa, x-ray diffraction data show that the yellow part on the surface is Bi2TeO5, while the Bi2Te3 single crystal is still the major phase as the inside part. More interestingly, various crystal morphologies are observed by scanning electron microscope for Bi2Te3 near the boundary between Bi2Te3 and Bi2TeO5. Possible growth mechanisms for Bi2Te3 with different morphologies are discussed in detail. Project supported by the National Natural Science Foundation of China (Grant Nos. 10904013 and 11274060), the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK2009260 and BK20141329), and the Scientific Research Staring Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China.

  11. Control of the structural parameters in the (Zn – Zn16Ti single crystal growth

    Directory of Open Access Journals (Sweden)

    W. Wołczyński

    2011-10-01

    Full Text Available The (Zn - single crystal was obtained by means of the Bridgman system. Several growth rates were applied during the experiment. The graphite crucible was used in order to perform the solidification process. The unidirectional solidification occurred with the presence of the moving temperature field. The thermal gradient was positive so that the constrained growth of the single crystal was ensured. The (Zn single crystal was doped with small addition of titanium and copper. The titanium formed an intermetallic compound Zn16-Ti. The copper was solved in the solid solution (Zn. The precipitates of (Zn and Zn16-Ti formed a stripes localized cyclically along the single crystal length. The intermetallic compound Zn16-Ti strengthened the (Zn single crystal. The structural transitions were observed in the stripes with the increasing solidification rate. Within the first range of the solidification rates ( the irregular L-shape rod-like intermetalliccompoundwas revealed. At the- threshold growth rate branches disappear continuously till the growth rate equal to. At the same range of growth rates the regular lamellar eutectic structure (Zn – Zn16-Ti appeared continuously and it existed exclusively till the second threshold growth rate equal to. Above the second threshold growth rate the regular rod-like eutectic structure was formed, only. Thegeneral theory for the stationary eutectic solidification was developed. According to this theory the eutectic structure localized within the stripes is formed under stationary state. Therefore, the criterion of the minimum entropy production defines well the stationary solidification. The entropy production was calculated for the regular rod-like eutectic structure formation and for the regular lamellar eutectic structure formation. It was postulated that the observed structure are subjected to the competition. That is why the structural transitionwere observed at therevealedthreshold growth rates.Moreover, it was

  12. Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light.

    Science.gov (United States)

    Ooi, Amanda; Wong, Aloysius; Ng, Tien Khee; Marondedze, Claudius; Gehring, Christoph; Ooi, Boon S

    2016-09-23

    Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.

  13. Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light

    KAUST Repository

    Ooi, Amanda Siok Lee

    2016-09-23

    Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.

  14. Vibrio cholerae biofilm growth program and architecture revealed by single-cell live imaging.

    Science.gov (United States)

    Yan, Jing; Sharo, Andrew G; Stone, Howard A; Wingreen, Ned S; Bassler, Bonnie L

    2016-09-06

    Biofilms are surface-associated bacterial communities that are crucial in nature and during infection. Despite extensive work to identify biofilm components and to discover how they are regulated, little is known about biofilm structure at the level of individual cells. Here, we use state-of-the-art microscopy techniques to enable live single-cell resolution imaging of a Vibrio cholerae biofilm as it develops from one single founder cell to a mature biofilm of 10,000 cells, and to discover the forces underpinning the architectural evolution. Mutagenesis, matrix labeling, and simulations demonstrate that surface adhesion-mediated compression causes V. cholerae biofilms to transition from a 2D branched morphology to a dense, ordered 3D cluster. We discover that directional proliferation of rod-shaped bacteria plays a dominant role in shaping the biofilm architecture in V. cholerae biofilms, and this growth pattern is controlled by a single gene, rbmA Competition analyses reveal that the dense growth mode has the advantage of providing the biofilm with superior mechanical properties. Our single-cell technology can broadly link genes to biofilm fine structure and provides a route to assessing cell-to-cell heterogeneity in response to external stimuli.

  15. Single crystal growth and optical properties of a transparent perovskite oxide LaInO3

    Science.gov (United States)

    Jang, Dong Hyun; Lee, Woong-Jhae; Sohn, Egon; Kim, Hyung Joon; Seo, Dongmin; Park, Ju-Young; Choi, E. J.; Kim, Kee Hoon

    2017-03-01

    Transparent LaInO3 single crystals have been grown using the optical floating zone method. Optimal growth, resulting in the highest optical transparency and best crystallinity, has been found at a growth speed of 15 mm/h and an O2 gas pressure of 10 bar. Under these conditions, single crystals as large as ˜4 × 4 mm2 have been obtained. Chemical compositions and structural analyses reveal that the resulting LaInO3 single crystal is stoichiometric without any impurity phase and forms an orthorhombic perovskite structure. Optical transmission spectra exhibit multiple optical transitions in a wide spectral range (0.5-4.2 eV). Although the main optical absorption occurs at ˜4.13 eV, weak absorption starts to develop from ˜1.4 eV, in agreement with an activation energy of ˜0.7 eV derived from electrical resistivity measurements. The dielectric constant ɛ is found to be 23.7 at room temperature. This LaInO3 single crystal can be used as a transparent perovskite substrate for growing oxide semiconductors with lattice constants close to ˜4.12 Å, such as doped BaSnO3.

  16. Chirality-Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and Scalable Production

    Science.gov (United States)

    2016-09-15

    AFRL-AFOSR-VA-TR-2016-0319 Chirality-Controlled Growth of Single -Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and...controlled growth of single -wall carbon nanotubes using vapor phase epitaxy: mechanistic understanding and scalable production FA9550-14-1-0115 Zhou...controlled synthesis of single -wall carbon nanotubes. Firstly, we have successfully demonstrated a vapor-phase-epitaxy-analogous general strategy for

  17. Nanostructuring of Solar Cell Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    Solar energy is by far the most abundant renewable energy source available, but the levelized cost of solar energy is still not competitive with that of fossil fuels. Therefore there is a need to improve the power conversion effciency of solar cells without adding to the production cost. The main...... objective of this PhD thesis is to develop nanostructured silicon (Si) solar cells with higher power conversion efficiency using only scalable and cost-efficient production methods. The nanostructures, known as 'black silicon', are fabricated by single-step, maskless reactive ion etching and used as front...... texturing of different Si solar cells. Theoretically the nanostructure topology may be described as a graded refractive index in a mean-field approximation between air and Si. The optical properties of the developed black Si were simulated and experimentally measured. Total AM1.5G-weighted average...

  18. Single Nanoparticle Plasmonic Sensors

    Directory of Open Access Journals (Sweden)

    Manish Sriram

    2015-10-01

    Full Text Available The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed.

  19. Tribology. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts.

    Science.gov (United States)

    Gosvami, N N; Bares, J A; Mangolini, F; Konicek, A R; Yablon, D G; Carpick, R W

    2015-04-03

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation. Copyright © 2015, American Association for the Advancement of Science.

  20. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.; Boehly, T.R.; Bradley, D.K.; Smalyuk, V.A.; Ofer, D.; McKenty, P.W.; Glendinning, S.G.; Kalantar, D.H.; Watt, R.G.; Gobby, P.L.; Willi, O.; Taylor, R.J.

    1997-01-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%endash 7% over a 600-μm-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-μm and 60-μm wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-μm-thick polystyrene foam buffer layer resulted in reduced growth of the 31-μm perturbation and essentially unchanged growth for the 60-μm case when compared to targets without foam. copyright 1997 American Institute of Physics

  1. Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, M. Anwar [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511 (Japan); Tanaka, Isao [Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511 (Japan); Tanaka, Takaho; Khan, A. Ullah [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Mori, Takao, E-mail: MORI.Takao@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8671 (Japan)

    2016-01-15

    We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].

  2. Melt growth and properties of bulk BaSnO3 single crystals

    Science.gov (United States)

    Galazka, Z.; Uecker, R.; Irmscher, K.; Klimm, D.; Bertram, R.; Kwasniewski, A.; Naumann, M.; Schewski, R.; Pietsch, M.; Juda, U.; Fiedler, A.; Albrecht, M.; Ganschow, S.; Markurt, T.; Guguschev, C.; Bickermann, M.

    2017-02-01

    We present the first-time growth of bulk BaSnO3 single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO3 amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g). X ray powder diffraction identified only the BaSnO3 perovskite phase, while narrow rocking curves having a full width at half maximum of 26 arcsec and etch pit densities below 106 cm-2 confirm a high degree of structural perfection of the single crystals. In this respect they surpass the structural properties of those single crystals that were reported in the literature. The electrical conductivity of nominally undoped crystals depends on the growth conditions and ranges from insulating to medium n-type conductivity. After post-growth annealing in an oxidizing atmosphere undoped crystals are generally insulating. Doping the crystals with lanthanum during growth results in a high n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an electron concentration of 3.3  ×  1019 cm-3 and an electron mobility of 219 cm2 V-1 s-1. Based on optical absorption measurements we determined an energy of 3.17  ±  0.04 eV at 5 K and of 2.99  ±  0.04 eV at 297 K for the indirect band gap of BaSnO3.

  3. Review on one-dimensional nanostructures prepared by electrospinning and atomic layer deposition

    International Nuclear Information System (INIS)

    Szilágyi, Imre Miklós; Nagy, Dávidné

    2014-01-01

    This paper reviews the various lD nanostructures, which were prepared by electrospinning and atomic layer deposition (ALD). On the one hand, electrospinning served to make sacrificial polymer templates for the ALD growth; and thus various single or multilayer inorganic nanotubes were obtained. On the other hand, polymer, polymer/inorganic or inorganic nanowire templates were produced by electrospinning. By a consecutive ALD reaction various core/shell nanowires were synthesized

  4. Novel single nucleotide polymorphisms in candidate genes for growth in tilapia ( Oreochromis niloticus

    Directory of Open Access Journals (Sweden)

    Breidy Lizeth Cuevas-Rodríguez

    2016-06-01

    Full Text Available ABSTRACT The objective of the present work was to identify and validate single nucleotide variations located in candidate genes to growth traits in tilapia (Oreochromis niloticus. Two transitions were identified in the promoter region of the growth hormone gene (GH; eight nucleotide changes were identified in introns and promoter region of the IGF-I gene; and a transition (T/C was identified in the Myogenin gene (MyoG. The highest genotypic frequency (0.8 for GHpA1 and MyoG was found in the GG and TT homozygous individuals, while the highest frequency (0.9 for GHpB1 was observed in the CT heterozygous fish. There was no genotypic frequency in the CC homozygous tilapia for the GHpB1 and MyoG markers. Based on their allelic frequencies, validation as novel single nucleotide polymorphisms (SNP of those variations located at O. niloticus GH and MyoG genes was possible. These new markers will allow their association with growth traits in tilapia to be exploited in order to determine their potential use as assisted-selection markers.

  5. Single-Mode Deceleration Stage Rayleigh-Taylor Instability Growth in Cylindrical Implosions

    Science.gov (United States)

    Sauppe, J. P.; Palaniyappan, S.; Bradley, P. A.; Batha, S. H.; Loomis, E. N.; Kline, J. L.; Srinivasan, B.; Bose, A.; Malka, E.; Shvarts, D.

    2017-10-01

    We present design calculations demonstrating the feasibility of measuring single-mode deceleration stage Rayleigh-Taylor instability (RTI) growth at a factor of four convergence. RTI growth rates are modified as a result of convergence [Bell LA-1321, 1951], and cylindrical targets are considered here, as they allow direct diagnostic access along the interface. The 2D computations, performed with the radiation-hydrodynamics code xRAGE [Gittings et al., CSD 2008] utilizing a new laser ray-tracing package, predict growth factors of 6 to 10 for mode 10 and 4 to 6 for mode 4, both of high interest in evaluating inertial confinement fusion capsule degradation mechanisms [Bose et al., this conference]. These results compare favorably to a linear theory [Epstein, PoP 2004] and to a buoyancy-drag model [Srebro et al., LPB 2003], which accounts for the linear and non-linear stages. Synthetic radiographs, produced by combining 2D computations of axial and transverse cross-sections, indicate this growth will be observable, and these will be compared to experimental data obtained at the OMEGA laser facility. Work performed by Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the National Nuclear Security Administration of the U.S. Department of Energy. (LA-UR-17-25608).

  6. Growth kinetics of protein single crystals in the gel acupuncture technique

    Science.gov (United States)

    García-Ruiz, Juan Manuel; Moreno, Abel

    1997-07-01

    The growth of single crystals of tetragonal HEW lysozyme and thaumatin I into glass capillaries was monitored by time lapse video-microscopy. The crystals were obtained by unidirectional transport of the precipitating agent through capillaries of internal diameter ranging from 0.2 to 1.2 mm, using the gel acupuncture technique. For crystals growing from true protein solutions, the measured average growth rates varies with capillary diameter from 1.7 to 3.7 Å/s for thaumatin and from 2.8 to 22 Å/s for lysozyme. The measured average growth rates for crystals growing into gelled protein solutions were 1.8 Å/s for thaumatin and 2.5 Å/s for lysozyme. The trend in the variation of the growth rate with time is similar and suggests that, for capillaries with internal radius lower than 0.8 mm, diffusion dominates the global mass transport control. However, the existence of convection rolls near the crystal-solution interface and close to zones with high density gradient cannot be discarded.

  7. Synthesis, growth, structure determination and optical properties of chalcone derivative single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Karthi, S., E-mail: girijaeaswaradas@gmail.com; Girija, E. K., E-mail: girijaeaswaradas@gmail.com [Department of Physics, Periyar University, Salem - 636011 (India)

    2014-04-24

    Acquiring large nonlinear optical (NLO) efficient organic material is essential for the development of optoelectronics and photonic devices. Chalcone is the donor - Π - acceptor - Π - donor (D-Π-A-Π-D) type conjugated molecule with appreciable hyperpolarizability of potential interest in NLO applications. The addition of vinyl and electron donor groups in the chalcone molecule may enhance the second harmonic generation (SHG) efficiency. Here we report the synthesis, crystal growth and characterization of a chalcone derivative 1-(4-methylphenyl)-5-(4-methoxyphenyl)-penta-2,4-dien-1-one (MPMPP). The MPMPP crystal was grown by slow evaporation solution growth technique from acetone. The grown crystal structure was studied by single crystal X-ray diffraction. The SHG efficiency of the grown crystal was determined by Kurtz and Perry method.

  8. Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

    Directory of Open Access Journals (Sweden)

    Qian Yong

    2009-01-01

    Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

  9. Reactivity of cycloparaphenylenes: Studying the possible growth of single-walled carbon nanotubes with DFT methods

    Science.gov (United States)

    Reche-Tamayo, M.; Pérez-Guardiola, A.; Pérez-Jiménez, A. J.; Sancho-García, J. C.

    2018-04-01

    We perform a theoretical study on a set of carbon nanorings (CycloParaPhenylenes or CPP) envisioned as molecular templates for the selective synthesis of carbon nanotubes. The shape of these precursors, originating from bending n phenylene units in para position until forming the corresponding nanoring [n]CPP, may drive the growth of armchair single-walled nanotubes. This kinetic and thermodynamic study covers a set of molecules with different diameters, analyzing the exothermicity and the reaction path of a CPP-based radicaloid mechanism. The methodology employed is based on validated density functionals for mechanistic studies, shedding light on the viability of this synthetic pathway.

  10. Thin films of metal oxides on metal single crystals: Structure and growth by scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Galloway, H.C.

    1995-12-01

    Detailed studies of the growth and structure of thin films of metal oxides grown on metal single crystal surfaces using Scanning Tunneling Microscopy (STM) are presented. The oxide overlayer systems studied are iron oxide and titanium oxide on the Pt(III) surface. The complexity of the metal oxides and large lattice mismatches often lead to surface structures with large unit cells. These are particularly suited to a local real space technique such as scanning tunneling microscopy. In particular, the symmetry that is directly observed with the STM elucidates the relationship of the oxide overlayers to the substrate as well as distinguishing, the structures of different oxides

  11. Growth and characterization of 2-Methylimidazolium D-tartrate single crystal

    Science.gov (United States)

    Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.

    2011-03-01

    Single crystal of 2-Methylimidazolium D-tartrate (2MImdT; C8N2O6H12) has been grown by slow evaporation solution growth technique at room temperature using mixed solvents of ethanol and deionized water. Single crystal X-ray diffraction study confirms that 2-Methylimidazolium D-tartrate belongs to monoclinic crystal system with non-centrosymmetric space group P21. The Fourier transform infrared spectrum of 2-Methylimidazolium D-tartrate reveals the presence of methyl and carboxyl functional groups in the compound. The mechanical properties of 2MImdT crystal were studied. The theoretical factor group analysis predicts 168 optical modes in the title compound. The dielectric behavior of 2MImdT crystals was studied at different frequencies and temperatures. Decomposition and melting point of 2MImdT were found using thermal measurements. SHG behavior of the title compound was demonstrated using Q-switched Nd:YAG laser.

  12. Three-Dimensional ZnO Hierarchical Nanostructures: Solution Phase Synthesis and Applications

    Directory of Open Access Journals (Sweden)

    Xiaoliang Wang

    2017-11-01

    Full Text Available Zinc oxide (ZnO nanostructures have been studied extensively in the past 20 years due to their novel electronic, photonic, mechanical and electrochemical properties. Recently, more attention has been paid to assemble nanoscale building blocks into three-dimensional (3D complex hierarchical structures, which not only inherit the excellent properties of the single building blocks but also provide potential applications in the bottom-up fabrication of functional devices. This review article focuses on 3D ZnO hierarchical nanostructures, and summarizes major advances in the solution phase synthesis, applications in environment, and electrical/electrochemical devices. We present the principles and growth mechanisms of ZnO nanostructures via different solution methods, with an emphasis on rational control of the morphology and assembly. We then discuss the applications of 3D ZnO hierarchical nanostructures in photocatalysis, field emission, electrochemical sensor, and lithium ion batteries. Throughout the discussion, the relationship between the device performance and the microstructures of 3D ZnO hierarchical nanostructures will be highlighted. This review concludes with a personal perspective on the current challenges and future research.

  13. Properties of NiO nanostructured growth using thermal dry oxidation of nickel metal thin film for hydrogen gas sensing at room temperature

    Science.gov (United States)

    Abubakar, Dauda; Ahmed, Naser M.; Mahmud, Shahrom; Algadri, Natheer A.

    2017-07-01

    A highly qualitative NiO nanostructure was synthesized using thermal dry oxidation of metallic Ni thin films on ITO/glass using the RF sputtering technique. The deposited nickel thin films were oxidized in air ambient at 550 °C inside a furnace. The structural and surface morphologies, and the electrical and gas sensing properties of the NiO nanostructure were examined. An x-ray diffraction analysis demonstrated that the NiO nanostructure has a cubic structure with orientation of the most intense peak at (2 0 0), and shows good crystalline quality. Finite-element scanning electron microscopy and energy dispersive x-ray spectroscopy results revealed O and Ni present in the treated samples, indicating a pure NiO nanostructure composition obtained with high porosity. The electrical properties of the oxidize Ni thin films showed a p-type NiO thin film semiconductor. A hydrogen gas sensing measurement was made at different operating temperatures and different gas concentrations with a detection limit of 30 ppm concentration. The sensor device shows great sensing properties with an excellent sensitivity (310%) at room temperature, which decreases with an increase in the operating temperature. Superfast response and recovery times of 6 and 0.5 s, respectively, were observed with the device at 150 °C operating temperature.

  14. Quantitative super-resolution single molecule microscopy dataset of YFP-tagged growth factor receptors.

    Science.gov (United States)

    Lukeš, Tomáš; Pospíšil, Jakub; Fliegel, Karel; Lasser, Theo; Hagen, Guy M

    2018-01-19

    Super-resolution single molecule localization microscopy (SMLM) is a method for achieving resolution beyond the classical limit in optical microscopes (approx. 200 nm laterally). Yellow fluorescent protein (YFP) has been used for super-resolution single molecule localization microscopy, but less frequently than other fluorescent probes. Working with YFP in SMLM is a challenge because a lower number of photons are emitted per molecule compared to organic dyes which are more commonly used. Publically available experimental data can facilitate development of new data analysis algorithms. Four complete, freely available single molecule super-resolution microscopy datasets on YFP-tagged growth factor receptors expressed in a human cell line are presented including both raw and analyzed data. We report methods for sample preparation, for data acquisition, and for data analysis, as well as examples of the acquired images. We also analyzed the SMLM data sets using a different method: super-resolution optical fluctuation imaging (SOFI). The two modes of analysis offer complementary information about the sample. A fifth single molecule super-resolution microscopy dataset acquired with the dye Alexa 532 is included for comparison purposes. This dataset has potential for extensive reuse. Complete raw data from SMLM experiments has typically not been published. The YFP data exhibits low signal to noise ratios, making data analysis a challenge. These data sets will be useful to investigators developing their own algorithms for SMLM, SOFI, and related methods. The data will also be useful for researchers investigating growth factor receptors such as ErbB3. © The Author(s) 2018. Published by Oxford University Press.

  15. Growth of high-crystalline, single-layer hexagonal boron nitride on recyclable platinum foil.

    Science.gov (United States)

    Kim, Gwangwoo; Jang, A-Rang; Jeong, Hu Young; Lee, Zonghoon; Kang, Dae Joon; Shin, Hyeon Suk

    2013-04-10

    Hexagonal boron nitride (h-BN) is gaining significant attention as a two-dimensional dielectric material, along with graphene and other such materials. Herein, we demonstrate the growth of highly crystalline, single-layer h-BN on Pt foil through a low-pressure chemical vapor deposition method that allowed h-BN to be grown over a wide area (8 × 25 mm(2)). An electrochemical bubbling-based method was used to transfer the grown h-BN layer from the Pt foil onto an arbitrary substrate. This allowed the Pt foil, which was not consumed during the process, to be recycled repeatedly. The UV-visible absorption spectrum of the single-layer h-BN suggested an optical band gap of 6.06 eV, while a high-resolution transmission electron microscopy image of the same showed the presence of distinct hexagonal arrays of B and N atoms, which were indicative of the highly crystalline nature and single-atom thickness of the h-BN layer. This method of growing single-layer h-BN over large areas was also compatible with use of a sapphire substrate.

  16. Seeded growth of boron arsenide single crystals with high thermal conductivity

    Science.gov (United States)

    Tian, Fei; Song, Bai; Lv, Bing; Sun, Jingying; Huyan, Shuyuan; Wu, Qi; Mao, Jun; Ni, Yizhou; Ding, Zhiwei; Huberman, Samuel; Liu, Te-Huan; Chen, Gang; Chen, Shuo; Chu, Ching-Wu; Ren, Zhifeng

    2018-01-01

    Materials with high thermal conductivities are crucial to effectively cooling high-power-density electronic and optoelectronic devices. Recently, zinc-blende boron arsenide (BAs) has been predicted to have a very high thermal conductivity of over 2000 W m-1 K-1 at room temperature by first-principles calculations, rendering it a close competitor for diamond which holds the highest thermal conductivity among bulk materials. Experimental demonstration, however, has proved extremely challenging, especially in the preparation of large high quality single crystals. Although BAs crystals have been previously grown by chemical vapor transport (CVT), the growth process relies on spontaneous nucleation and results in small crystals with multiple grains and various defects. Here, we report a controllable CVT synthesis of large single BAs crystals (400-600 μm) by using carefully selected tiny BAs single crystals as seeds. We have obtained BAs single crystals with a thermal conductivity of 351 ± 21 W m-1 K-1 at room temperature, which is almost twice as conductive as previously reported BAs crystals. Further improvement along this direction is very likely.

  17. Single-cell analysis of growth and cell division of the anaerobe Desulfovibrio vulgaris Hildenborough

    Directory of Open Access Journals (Sweden)

    Anouchka eFievet

    2015-12-01

    Full Text Available Recent years have seen significant progress in understanding basic bacterial cell cycle properties such as cell growth and cell division. While characterization and regulation of bacterial cell cycle is quite well documented in the case of fast growing aerobic model organisms, no data has been so far reported for anaerobic bacteria. This lack of information in anaerobic microorganisms can mainly be explained by the absence of molecular and cellular tools such as single cell microscopy and fluorescent probes usable for anaerobes and essential to study cellular events and/or subcellular localization of the actors involved in cell cycle.In this study, single-cell microscopy has been adapted to study for the first time, in real time, the cell cycle of a bacterial anaerobe, Desulfovibrio vulgaris Hildenborough (DvH. This single-cell analysis provides mechanistic insights into the cell division cycle of DvH, which seems to be governed by the recently discussed so-called incremental model that generates remarkably homogeneous cell sizes. Furthermore, cell division was reversibly blocked during oxygen exposure. This may constitute a strategy for anaerobic cells to cope with transient exposure to oxygen that they may encounter in their natural environment, thereby contributing to their aerotolerance. This study lays the foundation for the first molecular, single-cell assay that will address factors that cannot otherwise be resolved in bulk assays and that will allow visualization of a wide range of molecular mechanisms within living anaerobic cells.

  18. Growth of zinc oxide nanostructures

    Indian Academy of Sciences (India)

    temperature of 400◦C by unbalanced magnetron sputtering and PLD techniques. Alternately a simple chemical route .... Zn layer was very critical and nanowhiskers did not form when the thicknesses was more than 20 nm. Furthermore, the ... crystallites are much smaller than incident λ. Also this mode is present between.

  19. Growth of zinc oxide nanostructures

    Indian Academy of Sciences (India)

    Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer ZnO(50 nm)/Zn(20 nm)/ZnO(2 m) structure on a polished stainless steel (SS) substrate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 m length was observed after a ...

  20. Growth of zinc oxide nanostructures

    Indian Academy of Sciences (India)

    Abstract. Zinc oxide (ZnO) nanowhiskers have been prepared using a multilayer. ZnO(50 nm)/Zn(20 nm)/ZnO(2 µm) structure on a polished stainless steel (SS) sub- strate by high rate magnetron sputtering. The formation of uniformly distributed ZnO nanowhiskers with about 20 nm dia. and 2 to 5 µm length was observed ...

  1. Growth of ZrSiO4 single crystal by flux method

    International Nuclear Information System (INIS)

    Ushio, Masumi; Nishitani, Yoshinari

    1982-01-01

    ZrSiO 4 single crystals were grown from the Na 2 O.3 V 2 O 5 fluxed melt at constant soaking temperatures of 900 0 C and 1000 0 C for periods up to 1710h, using the natural zircon seeds. Temperature difference between the seed and nutrient was 0.5 -- 5 0 C. A solubility curve of the natural zircon in Na 2 O.3 V 2 O 5 was determined. It was found that about 5.7g of the natural crystal dissolved in Na 2 O.3 V 2 O 5 in 48h at 1000 0 C and about 7.5g at 1200 0 C. .the maximum growth weight was about 0.35 2 g under conditions of the temperature difference of 2 0 C and the soaking for 1205h at 1000 0 C. The grown crystal was initially bounded with the c-, m-, p-, a-planes and very small planes consisting of the u- and x-, and finally bounded with the m- and p-planes. The observed linear growth rates of planes of ZrSiO 4 single crystals were in the following order:a(100) > c(001) > p(111) > m(110). The growth rates of a- and m-planes were about 5 -- 7 x 10 -4 mm/h and 0.9 -- 1.0 x 10 -4 mm/h, respectively. The growth hillocks of rounded triangular shape and elliptic shape extended to the direction of c-axis, were observed on the p- and m-planes, respectively. The observed step distence of the spiral and the step height were about 0.97 5 μm and 0.17 2 μm, respectively. The observed linear rate of advance of the step on the m-plane was about 0.4 0 -- 1.2 x 10 -8 cm/s. A linear growth rate of the m-plane was then calculated to be 0.2 5 -- 0.7 1 x 10 -4 mm/h by the BCF theory, which agreed in order of magnitude with the observes growth rate of the m-plabe. (author)

  2. ZnO nanostructures and their applications

    CERN Document Server

    Xiaowei, Sun

    2011-01-01

    This book focuses on the various functional properties and potential applications of one-dimensional ZnO nanostructures, from basic principles to our most recent discoveries. It comprises experimental analysis of various properties of ZnO nanostructures, preparation techniques, research methods, and some promising applications. The areas of focus include ZnO-based gas/biochemical sensing devices, field emitters, solar cells, light-emitting diodes, e-papers, and single-nanowire-based transistors.

  3. Single and combined toxicity of copper and cadmium to H. vulgare growth and heavy metal bioaccumulation

    Directory of Open Access Journals (Sweden)

    Žaltauskaitė J.

    2013-04-01

    Full Text Available The single and combined effects of copper (Cu and cadmium (Cd (0.1-10 mg L−1 in spring barley (Hordeum vulgare L. plants grown in hydroponics are investigated. The aim of the study was to investigate the interactive effect of the binary mixture of Cu and Cd to the growth of H. vulgare and accumulation of these metals by the plants. Single and combined metal treatment led to major effects in the growth of roots and shoots and dry weight of barley. Exposure to metals altered the content of photosynthetic pigments and caused lipid peroxidation. It was observed that combined effects of heavy metals to plants are endpoint and concentration depending. The binary mixture Cu+Cd exhibited additive or less than additive interaction for dry weight, root length and shoot height. Analysis of tissue metal concentrations showed that Cu and Cd were mainly accumulated in the roots and the combination of Cu+Cd had less than additive response of metal bioaccumulation in the leaves and roots.

  4. Multiple growths of epitaxial lift-off solar cells from a single InP substrate

    International Nuclear Information System (INIS)

    Lee, Kyusang; Shiu, Kuen-Ting; Zimmerman, Jeramy D.; Forrest, Stephen R.; Renshaw, Christopher K.

    2010-01-01

    We demonstrate multiple growths of flexible, thin-film indium tin oxide-InP Schottky-barrier solar cells on a single InP wafer via epitaxial lift-off (ELO). Layers that protect the InP parent wafer surface during the ELO process are subsequently removed by selective wet-chemical etching, with the active solar cell layers transferred to a thin, flexible plastic host substrate by cold welding at room temperature. The first- and second-growth solar cells exhibit no performance degradation under simulated Atmospheric Mass 1.5 Global (AM 1.5G) illumination, and have a power conversion efficiency of η p =14.4±0.4% and η p =14.8±0.2%, respectively. The current-voltage characteristics for the solar cells and atomic force microscope images of the substrate indicate that the parent wafer is undamaged, and is suitable for reuse after ELO and the protection-layer removal processes. X-ray photoelectron spectroscopy, reflection high-energy electron diffraction observation, and three-dimensional surface profiling show a surface that is comparable or improved to the original epiready wafer following ELO. Wafer reuse over multiple cycles suggests that high-efficiency; single-crystal thin-film solar cells may provide a practical path to low-cost solar-to-electrical energy conversion.

  5. Terminating DNA Tile Assembly with Nanostructured Caps.

    Science.gov (United States)

    Agrawal, Deepak K; Jiang, Ruoyu; Reinhart, Seth; Mohammed, Abdul M; Jorgenson, Tyler D; Schulman, Rebecca

    2017-10-24

    Precise control over the nucleation, growth, and termination of self-assembly processes is a fundamental tool for controlling product yield and assembly dynamics. Mechanisms for altering these processes programmatically could allow the use of simple components to self-assemble complex final products or to design processes allowing for dynamic assembly or reconfiguration. Here we use DNA tile self-assembly to develop general design principles for building complexes that can bind to a growing biomolecular assembly and terminate its growth by systematically characterizing how different DNA origami nanostructures interact with the growing ends of DNA tile nanotubes. We find that nanostructures that present binding interfaces for all of the binding sites on a growing facet can bind selectively to growing ends and stop growth when these interfaces are presented on either a rigid or floppy scaffold. In contrast, nucleation of nanotubes requires the presentation of binding sites in an arrangement that matches the shape of the structure's facet. As a result, it is possible to build nanostructures that can terminate the growth of existing nanotubes but cannot nucleate a new structure. The resulting design principles for constructing structures that direct nucleation and termination of the growth of one-dimensional nanostructures can also serve as a starting point for programmatically directing two- and three-dimensional crystallization processes using nanostructure design.

  6. A robust seeding technique for the growth of single grain (RE)BCO and (RE)BCO–Ag bulk superconductors

    Science.gov (United States)

    Namburi, Devendra K.; Shi, Yunhua; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

    2018-04-01

    Bulk, single grains of RE–Ba–Cu–O [(RE)BCO] high temperature superconductors have significant potential for a wide range of applications, including trapped field magnets, energy storage flywheels, superconducting mixers and magnetic separators. One of the main challenges in the production of these materials by the so-called top seeded melt growth technique is the reliable seeding of large, single grains, which are required for high field applications. A chemically aggressive liquid phase comprising of BaCuO2 and CuO is generated during the single grain growth process, which comes into direct contact with the seed crystal either instantaneously or via infiltration through a buffer pellet, if employed in the process. This can cause either partial or complete melting of the seed, leading subsequently to growth failure. Here, the underlying mechanisms of seed crystal melting and the role of seed porosity in the single grain growth process are investigated. We identify seed porosity as a key limitation in the reliable and successful fabrication of large grain (RE)BCO bulk superconductors for the first time, and propose the use of Mg-doped NdBCO generic seeds fabricated via the infiltration growth technique to reduce the effects of seed porosity on the melt growth process. Finally, we demonstrate that the use of such seeds leads to better resistance to melting during the single grain growth process, and therefore to a more reliable fabrication technique.

  7. Synthesis of PbI(2) single-layered inorganic nanotubes encapsulated within carbon nanotubes.

    Science.gov (United States)

    Cabana, Laura; Ballesteros, Belén; Batista, Eudar; Magén, César; Arenal, Raúl; Oró-Solé, Judith; Rurali, Riccardo; Tobias, Gerard

    2014-04-02

    The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. The role of the vascular endothelial growth factor/vascular endothelial growth factor receptors axis mediated angiogenesis in curcumin-loaded nanostructured lipid carriers induced human HepG2 cells apoptosis

    Directory of Open Access Journals (Sweden)

    Fengling Wang

    2015-01-01

    Full Text Available Background: Curcumin (diferuloylmethane, the active constituent of turmeric extract has potent anti-cancer properties have been demonstrated in hepatocellular carcinoma (HCC. However, its underlying molecular mechanism of therapeutic effects remains unclear. Vascular endothelial growth factor (VEGF and its receptors (VEGFRs have crucial roles in tumor angiogenesis. Purpose: The goal of this study was to investigate the role of the VEGF/VEGFRs mediated angiogenesis during the proliferation and apoptosis of human HepG2 hepatoma cell line and the effect of curcumin-loaded nanostructured lipid carriers (Cur-NLC. Materials and Methods: The proliferation of HepG2 cells was determined by methyl thiazolyl tetrazolium after exposure to Cur-NLC and native curcumin. Apoptosis was quantified by flow cytometry with annexin V-fluorescein isothiocyanate and propidium iodide staining. Cellular internalization of Cur-NLC was observed by fluorescent microscope. The level of VEGF was detected by enzyme-linked immunosorbent assay kits. The expression of VEGFRs was quantified by Western blotting. Results: Cur-NLC was more effective in inhibiting the proliferation and enhancing the apoptosis of HepG2 cells than native curcumin. Fluorescent microscope analysis showed that HepG2 cells internalized Cur-NLC more effectively than native curcumin. Furthermore, Cur-NLC down-regulated the level of VEGF and the expression of VEGFR-2, but had a slight effect on VEGFR-1. Conclusion: These results clearly demonstrated that Cur-NLC was more effective in anti-cancer activity than the free form of curcumin. These studies demonstrate for the 1 st time that Cur-NLC exerts an antitumor effect on HepG2 cells by modulating VEGF/VEGFRs signaling pathway.

  9. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R.; Yakobson, Boris I.; McCarty, Kevin F.; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S.

    2016-02-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional 'surface-limited' growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to -100 meV at a displacement field of 0.9 V nm-1.

  10. Sexual dimorphism and identification of single nucleotide polymorphism of growth hormone gene in muscovy duck

    Directory of Open Access Journals (Sweden)

    I. Ismoyowati

    2017-08-01

    Full Text Available This research was aimed to investigate the different growth and to identify growth hormone gene polymorphism in Muscovy ducks. Two hundred Muscovy day-old ducks consisting of white-plumed male and female duck, black and white-plumed male and female ducks. Body weight was recorded weekly and the obtained data were subject to T test. Primer design used the Custal X Program based on a database from the GeneBank Cairina moschata GH gene, partial cds (AB158762. Primer base sequence of GH gene was forward/Sequence: 5’-CTGGGGTTGTTTAGCTTGGA-3’ and reverse/Sequence: 5’-TAAACCTTCCCTGGCACAAC-3’. The DNA sequences were aligned by using the BioEdit version 7.7 for identification of the single nucleotide polymorphism. The result showed that male Muscovy duck produced higher an average body weight gain and more relative growth than those of females. The highest body weight gain was at three weeks old, and then it started to decrease at four weeks old. The sequencing PCR product obtained nucleotide polymorphism. AA genotype was observed at 136 t of black female Muscovy duck, CC in black and white male Muscovy duck, and white female Muscovy duck. Conclusively, a body weight gain of 3-week-old male Muscovy ducks was higher than that of females and GH gene polymorphism was observed in Muscovy ducks.

  11. Growth and characterization of CdTe single crystals for radiation detectors

    CERN Document Server

    Funaki, M; Satoh, K; Ohno, R

    1999-01-01

    To improve the productivity of CdTe radiation detectors, the crystal growth by traveling heater method (THM) as well as the quality of the fabricated detectors were investigated. In the THM growth, optimization of the solvent volume was found to be essential because it affects the shape of the growth interface. The use of the slightly tilted seed from B was also effective to limit the generation of twins having different directions. Single-crystal (1 1 1) wafers, larger than 30x30 mm sup 2 were successfully obtained from a grown crystal of 50 mm diameter. Pt/CdTe/Pt detectors of dimensions 4x4x2 mm sup 3 , fabricated from the whole crystal ingot, showed an energy resolution (FWHM of 122 keV peak from a sup 5 sup 7 Co source) between 6% and 8%. Similarly, Pt/CdTe/In detectors of dimensions 2x2x0.5 mm sup 3 showed a resolution better than 3%. These characteristics encourage the practical applications of various types of CdTe detectors.

  12. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    International Nuclear Information System (INIS)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-01-01

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  13. PREFACE: Self-organized nanostructures

    Science.gov (United States)

    Rousset, Sylvie; Ortega, Enrique

    2006-04-01

    the EUROCORES SONS Programme under the auspices of the European Science Foundation and the VI Framework Programme of the European Community. It was also funded by CNRS `formation permanente'. Major topics relevant to self-organization are covered in these papers. The first two papers deal with the physics of self-organized nucleation and growth. Both metal and semiconductor templates are investigated. The paper by Meyer zu Heringdorf focuses on the mesoscopic patterns formed by the Au-induced faceting of vicinal Si (001). Repain et al describe how uniform and long-range ordered nanostructures are built on a surface by using nucleation on a point-defect array. Electronic properties of such self-organized systems are reviewed by Mugarza and Ortega. The next three papers deal with molecules and self-organization. In the paper presented by Kröger, molecules are deposited on vicinal Au surfaces and are studied by STM. A very active field in self-organized nanostructures is the chemical route for nanoparticle synthesis. The paper by Piléni deals with self-organization of inorganic crystals produced by evaporation of a solution, also called colloids. Their physical properties are also treated. Gacoin et al illustrate chemical synthesis, including the template approach, using organized mesoporous silica films for the production of semiconductor or metal arrays of particles. An alternative method is developed in the paper by Allongue and Maroun which is the electrochemical method of building arrays of nanostructures. Ultimately, self-organization is a very interdisciplinary field. There is also an attempt in this issue to present some of the challenges using biology. The paper by Belamie et al deals with the self-assembly of biological macromolecules, such as chitin and collagen. Finally, Molodtsov and co-workers describe how a biological template can be used in order to achieve novel materials made of hybrid metallo-organic nanostructures.

  14. Irradiation-Induced Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Birtcher, R.C.; Ewing, R.C.; Matzke, Hj.; Meldrum, A.; Newcomer, P.P.; Wang, L.M.; Wang, S.X.; Weber, W.J.

    1999-08-09

    This paper summarizes the results of the studies of the irradiation-induced formation of nanostructures, where the injected interstitials from the source of irradiation are not major components of the nanophase. This phenomena has been observed by in situ transmission electron microscopy (TEM) in a number of intermetallic compounds and ceramics during high-energy electron or ion irradiations when the ions completely penetrate through the specimen. Beginning with single crystals, electron or ion irradiation in a certain temperature range may result in nanostructures composed of amorphous domains and nanocrystals with either the original composition and crystal structure or new nanophases formed by decomposition of the target material. The phenomenon has also been observed in natural materials which have suffered irradiation from the decay of constituent radioactive elements and in nuclear reactor fuels which have been irradiated by fission neutrons and other fission products. The mechanisms involved in the process of this nanophase formation are discussed in terms of the evolution of displacement cascades, radiation-induced defect accumulation, radiation-induced segregation and phase decomposition, as well as the competition between irradiation-induced amorphization and recrystallization.

  15. Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

    NARCIS (Netherlands)

    Liszka, B.; Lenferink, Aufrid T.M.; Otto, Cornelis

    2016-01-01

    The growth of single, self- nucleated calcium carbonate crystals on a polysulfone (PSU) film was investigated with high resolution, time lapse Raman imaging. The Raman images were acquired on the interface of the polymer with the crystal. The growth of crystals could thus be followed in time. PSU is

  16. Shape evolution of nanostructures by thermal and ion beam processing. Modeling and atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Roentzsch, L.

    2007-07-01

    Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc

  17. Shape evolution of nanostructures by thermal and ion beam processing. Modeling and atomistic simulations

    International Nuclear Information System (INIS)

    Roentzsch, L.

    2007-01-01

    Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc

  18. Growth of tourmaline single crystals containing transition metal elements in hydrothermal solutions

    Science.gov (United States)

    Setkova, Tatiana; Shapovalov, Yury; Balitsky, Vladimir

    2011-03-01

    Interest in the growth of tourmaline single crystals is based on the promising piezoelectric and pyroelectric properties of this material compared to quartz crystals currently in use. Moreover, synthetic tourmaline can be used as a substitute for the natural stone in the jewelry industry similar to other synthetic analogues of gemstones. Single crystals of colored Co-, Ni-, Fe-, (Ni,Cr)-, (Ni,Fe)-, and (Co,Ni,Cr)-containing tourmalines with concentration of transition metal elements up to 16 wt% on a seed have been grown from complex boron-containing hydrothermal solutions at a range of temperatures 400-750 °C and pressures 100 MPa. Experiments were conducted under conditions of a thermal gradient in titanium and chromium-nickel autoclaves. Tourmaline growth on a seed crystal occurs only if separate tourmaline-forming components (monocrystalline corundum and quartz bars) are used as charge. All tourmalines specified above grow in analogous (+) direction of the optical axis with a speed of 0.05 mm/day by faces of the trigonal pyramid, except tourmalines containing chromium. They grow in analogous (+0001) direction with a speed 0.05 mm/day, and in antilogous (-0001) direction with a speed of 0.01 mm/day by faces of the trigonal pyramid and in prism direction with a speed of 0.001 mm/day. Along with the large single crystals, a great amount of finest (30-150 μm in size) tourmaline crystals was formed during the runs by spontaneous nucleation both on the surface of the seed crystals and in the charge.

  19. Flux Growth of Heavy Fermion LiV2O4 Single Crystals

    Science.gov (United States)

    Das, S.; Zong, X.; Niazi, A.; Johnston, D. C.

    2007-03-01

    The spinel-structure compound LiV2O4 is a rare d- electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior. In addition, it is known that small concentrations (< 1 mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report growth at 950--1030 ^oC of 1 mm^3 size octahedron-shaped LiV2O4 single crystals using a self- flux technique. The magnetic susceptibility of the as-grown crystals shows a Curie-like upturn at low temperatures arising from 0.5 mol% magnetic defects within the spinel structure. After annealing at 700 ^oC, the Curie-like upturn (and magnetic defects) disappeared in some crystals, thus revealing the known intrinsic nearly temperature-independent behavior below ˜20 K@. Preliminary heat capacity measurements on as-grown crystals containing magnetic defects showed a high linear specific heat coefficient γ = 450 mJ/ (mole K^2) at 1.8 K@. Additional electronic tranport, magnetic and thermal measurements on both as-grown and annealed crystals will be presented.

  20. Growth, structural and magnetic characterization of Al-substituted barium hexaferrite single crystals

    International Nuclear Information System (INIS)

    Vinnik, D.A.; Zherebtsov, D.A.; Mashkovtseva, L.S.; Nemrava, S.; Bischoff, M.; Perov, N.S.; Semisalova, A.S.; Krivtsov, I.V.; Isaenko, L.I.; Mikhailov, G.G.; Niewa, R.

    2014-01-01

    Highlights: • Growth of large Al-substituted crystals BaFe 12−x Al x O 19. • Al-content controllable by flux composition. • Crystallographic site preference of Al unraveled. • Magnetic characterization depending on Al-content. - Abstract: Large single crystals of aluminum-substituted M-type barium hexaferrite BaFe 12−x Al x O 19 were obtained from carbonate flux. The Al content in the crystals can be controlled via the Al content of the flux up to x = 1.1 according to single crystal X-ray structure refinements. Al shows a distinct preference to substitute Fe on crystallographic sites with high coordination numbers by oxygen atoms, whereas no significant amounts of Al can be found on a tetrahedrally coordinated site. An increasing amount of the aluminum dopant results in a monotonous reduction of the Curie temperature from 440 to 415 °C and the saturation magnetization at room temperature from 68 to 57 emu/g for single crystal and from 61 to 53 emu/g for powder samples

  1. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics

  2. Growth and detachment of single hydrogen bubbles in a magnetohydrodynamic shear flow

    Science.gov (United States)

    Baczyzmalski, Dominik; Karnbach, Franziska; Mutschke, Gerd; Yang, Xuegeng; Eckert, Kerstin; Uhlemann, Margitta; Cierpka, Christian

    2017-09-01

    This study investigates the effect of a magnetohydrodynamic (MHD) shear flow on the growth and detachment of single sub-millimeter-sized hydrogen gas bubbles. These bubbles were electrolytically generated at a horizontal Pt microelectrode (100 μ m in diameter) in an acidic environment (1 M H2SO4 ). The inherent electric field was superimposed by a homogeneous electrode-parallel magnetic field of up to 700 mT to generate Lorentz forces in the electrolyte, which drive the MHD flow. The growth and motion of the hydrogen bubble was analyzed by microscopic high-speed imaging and measurements of the electric current, while particle tracking velocimetry (μ PTV ) and particle image velocimetry (μ PIV ) were applied to measure the surrounding electrolyte flow. In addition, numerical flow simulations were performed based on the experimental conditions. The results show a significant reduction of the bubble growth time and detachment diameter with increasing magnetic induction, which is known to improve the efficiency of water electrolysis. In order to gain further insight into the bubble detachment mechanism, an analysis of the forces acting on the bubble was performed. The strong MHD-induced drag force causes the bubble to slowly slide away from the center of the microelectrode before its detachment. This motion increases the active electrode area and enhances the bubble growth rate. The results further indicate that at large current densities the coalescence of tiny bubbles formed at the foot of the main bubble might play an important role for the bubble detachment. Moreover, the occurrence of Marangoni stresses at the gas-liquid interface is discussed.

  3. A novel nano-structured GaAs solar cell

    Science.gov (United States)

    Liang, Dong; Gu, Anjia; Huo, Yijie; Yan, Jingzhou; Li, Shuang; Garnett, Erik; Pickett, Evan; Kang, Yangsen; Tan, Meiyueh; Cerruto, Antonio Xavier; Zhu, Jia; Hsu, Ching-Mei; Yao, Yan; Riaziat, Majid; Cui, Yi; Harris, James S.

    2011-03-01

    In this presentation, we will demonstrate a novel solar cell with nano-structured dense arrays of single crystal GaAs conformally grown on nanopillar templates with wafer-scale uniformity. The template is prepared via plasma enhanced etching with a monolayer of Si O2 nanospheres as a mask followed by wet chemical etching. The GaAs p-n junction with an AlGaAs passivation window layer is grown via metal-organic chemical vapor deposition (MOCVD). The rectangular shape of the nano single crystal GaAs reveals anisotropic lateral growth rates of GaAs along (011) and (01 1 directions, which can be engineered by tuning the As H3 flow and temperature during growth. Optical absorption measurements show the outstanding light trapping properties of the nano-structured cell, which agree with the simulation results. I-V characteristics show an efficiency of 1.67% for the nano GaAs solar cell, which is 15% higher than its planar control cell with the same thickness of 200nm. The efficiency is the highest among all the large area GaAs nanowire core-shell solar cells reported in literature by 2010.

  4. Translation effects on vertical Bridgman growth and optical, mechanical and surface analysis of 2-phenylphenol single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sadhasivam, S., E-mail: sadha.phy1@gmail.com [Department of Physics, Center for Crystal Growth, SSN College of Engineering, Tamil Nadu, India-603 110 (India); Perumal, Rajesh Narayana

    2016-05-06

    2-phenylphenol optical crystals were grown in cone ampoules using vertical Bridgman technique. Single crystal of 2-phenylphenol with 150 mm length has been grown. The inclination on the conical part of the ampoule reduces the growth defects in the 2-phenylphenol single crystal. The lattice parameters and structure studied using single crystal X-ray diffraction method. 2-phenylphenol single crystal belongs to orthorhombic space group Fdd2. The micro translation rate affects crystal growth of 2-phenylphenol crystal was studied. The translation rate dependent defects present in the crystal were investigated by transmittance, indentation and etching characterizations. The dislocation induced indentation crack lengths variations were studied. Etch pits and striations observed for the selective etchants furnish significant information on growth aspects and degree of defect present in the crystal.

  5. Sulfated glycopeptide nanostructures for multipotent protein activation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungsoo S.; Fyrner, Timmy; Chen, Feng; Álvarez, Zaida; Sleep, Eduard; Chun, Danielle S.; Weiner, Joseph A.; Cook, Ralph W.; Freshman, Ryan D.; Schallmo, Michael S.; Katchko, Karina M.; Schneider, Andrew D.; Smith, Justin T.; Yun, Chawon; Singh, Gurmit; Hashmi, Sohaib Z.; McClendon, Mark T.; Yu, Zhilin; Stock, Stuart R.; Hsu, Wellington K.; Hsu, Erin L.; Stupp , Samuel I. (NWU)

    2017-06-19

    Biological systems have evolved to utilize numerous proteins with capacity to bind polysaccharides for the purpose of optimizing their function. A well-known subset of these proteins with binding domains for the highly diverse sulfated polysaccharides are important growth factors involved in biological development and tissue repair. We report here on supramolecular sulfated glycopeptide nanostructures, which display a trisulfated monosaccharide on their surfaces and bind five critical proteins with different polysaccharide-binding domains. Binding does not disrupt the filamentous shape of the nanostructures or their internal β-sheet backbone, but must involve accessible adaptive configurations to interact with such different proteins. The glycopeptide nanostructures amplified signalling of bone morphogenetic protein 2 significantly more than the natural sulfated polysaccharide heparin, and promoted regeneration of bone in the spine with a protein dose that is 100-fold lower than that required in the animal model. These highly bioactive nanostructures may enable many therapies in the future involving proteins.

  6. Sea-urchin-like ZnO nanostructures on Si by oxidation of Zn metal powders: Structural and optical properties

    Science.gov (United States)

    Umar, A.; Kim, S. H.; Hahn, Y. B.

    2006-01-01

    High-density sea-urchin-like ZnO nanostructures were grown on Si(100) substrates by the oxidation of metallic Zn powders at a low growth temperature without the use of any catalyst or additives. The morphological studies indicated that the grown structures are uniformly dispersed on the substrate and exhibited a sea-urchin-like shape consisting of several thousands of nanorods in one array, each ZnO nanorod of these structures having the diameter of 20-50 nm with the length of 2-4 μm. The high-resolution transmission electron microscopy and selected area electron diffraction patterns showed that the prepared sea-urchin-like ZnO nanostructures were single crystalline with wurtzite hexagonal structure and preferably grown along the [0001] direction. Room temperature Raman scattering and photoluminescence studies found that the as-grown nanostructures have good crystal quality with the hexagonal wurtzite phase.

  7. Single crystal cupric oxide nanowires: Length- and density-controlled growth and gas-sensing characteristics

    Science.gov (United States)

    Duc, Le Duy; Le, Dang Thi Thanh; Duy, Nguyen Van; Hoa, Nguyen Duc; Hieu, Nguyen Van

    2014-04-01

    Nanowire structured p-type CuO semiconductor is a promising material for gas-sensing applications because of its unique electrical and optical properties. In this study, we demonstrate the length and density controlled synthesis of single crystal CuO nanowires (CuO NWs) by a simple and convenient thermal oxidation of high-purity copper foils in ambient atmosphere. The density and length of the CuO NWs are controlled by varying the oxidation temperature and heating duration to investigate their growth mechanism. As-synthesized materials are characterized by different techniques, such as X-ray diffraction, field emission-scanning electron microscopy, and high-resolution transmission electron microscopy. The gas-sensing characteristics of the CuO NWs are tested using hydrogen and ethanol gases. The results show that the CuO NWs could potentially sense hydrogen and ethanol gases given a working temperature of 400 °C.

  8. Some technological procedures and equipment for hydrothermal growth of single crystals

    International Nuclear Information System (INIS)

    Popolitov, V.I.; Lobachev, A.N.; Shapiro, A.Y.

    1986-01-01

    The authors have designed, installed and tested a quartz reactor with 200 cm 3 volume in order to directly observe the process of dissolution of solid ingredients, and the synthesis and seeded growth of crystals. The reactor is illustrated. Two C-A thermocouples were used during the experiments to measure the temperature distribution along the outer wall of the reactor in the upper and lower zone. A method is described that was used to grow pyro-and feroelectric single crystals from the ABO 4 group (A-Sb 3+ , Bi 3+ ; B-Nb 5+ , Ta 5+ , Sb 5+ ), and in particular SbSbO 4 , SbNbO 4 , and SbTaO 4

  9. Growth and characterization of single-crystal CVD diamond for radiation detection applications

    International Nuclear Information System (INIS)

    Tranchant, N.

    2008-01-01

    This work aimed at the study of the synthesis of single crystal diamond using the Microwave enhanced Chemical Vapour Deposition technique (MPCVD). The work enabled the development and optimisation of the growth conditions, from the study of the crystalline quality, of the material purity, and of its electronic properties. The assessment of the transport properties was the most determinant: the use of the time of flight (TOF) technique has enabled the measurement of the carrier mobilities and of their kinetic properties as a function of the temperature. When coupled with collected charge efficiency measurements, the work led to remarkable carrier mobility values obtained in the synthesised crystals (3000 cm 2 .V-1.s -1 ). Prepared samples were mounted as detection devices and used successfully in real conditions for the monitoring of ultra-fast pulses, as well as for neutron fluency monitoring, and for medical dosimeters for radiotherapy applications. (author)

  10. Chiral-Selective Growth of Single-Walled Carbon Nanotubes on Lattice-Mismatched Epitaxial Cobalt Nanoparticles

    DEFF Research Database (Denmark)

    He, Maoshuai; Jiang, Hua; Liu, Bilu

    2013-01-01

    Controlling chirality in growth of single-walled carbon nanotubes (SWNTs) is important for exploiting their practical applications. For long it has been conceptually conceived that the structural control of SWNTs is potentially achievable by fabricating nanoparticle catalysts with proper structures......-resolution environmental transmission electron microscope at a low CO pressure was recorded. We achieved highly preferential growth of semiconducting SWNTs (~90%) with an exceptionally large population of (6, 5) tubes (53%) in an ambient CO atmosphere. Particularly, we also demonstrated high enrichment in (7, 6) and (9, 4......) at a low growth temperature. These findings open new perspectives both for structural control of SWNTs and for elucidating the growth mechanisms....

  11. Theoretical studies on lattice-oriented growth of single-walled carbon nanotubes on sapphire

    Science.gov (United States)

    Li, Zhengwei; Meng, Xianhong; Xiao, Jianliang

    2017-09-01

    Due to their excellent mechanical and electrical properties, single-walled carbon nanotubes (SWNTs) can find broad applications in many areas, such as field-effect transistors, logic circuits, sensors and flexible electronics. High-density, horizontally aligned arrays of SWNTs are essential for high performance electronics. Many experimental studies have demonstrated that chemical vapor deposition growth of nanotubes on crystalline substrates such as sapphire offers a promising route to achieve such dense, perfectly aligned arrays. In this work, a theoretical study is performed to quantitatively understand the van der Waals interactions between SWNTs and sapphire substrates. The energetically preferred alignment directions of SWNTs on A-, R- and M-planes and the random alignment on the C-plane predicted by this study are all in good agreement with experiments. It is also shown that smaller SWNTs have better alignment than larger SWNTs due to their stronger interaction with sapphire substrate. The strong vdW interactions along preferred alignment directions can be intuitively explained by the nanoscale ‘grooves’ formed by atomic lattice structures on the surface of sapphire. This study provides important insights to the controlled growth of nanotubes and potentially other nanomaterials.

  12. Growth and characterization of Tm-doped Y 2O 3 single crystals

    Science.gov (United States)

    Mun, J. H.; Jouini, A.; Novoselov, A.; Guyot, Y.; Yoshikawa, A.; Ohta, H.; Shibata, H.; Waseda, Y.; Boulon, G.; Fukuda, T.

    2007-07-01

    The rare-earth sesquioxides (RE2O3, RE = Lu, Y and Sc) are promising host materials for solid-state lasers due to their low phonon energy and high thermal conductivity. On the other hand, Tm3+ and Yb3+ are preferable activators for advanced laser diode pumped solid-state lasers. In addition to that, Tm-doped materials can be used for eye-safe lasers application. Tm-doped Y2O3 single crystals were grown using the micro-pulling-down method. Crystals were transparent with gray and blue colors of 4.2 mm in diameter and 13-20 mm in length. The crystallinity was characterized using X-ray rocking curve analysis. Tm-doped Y2O3 single crystals have a good compositional homogeneity along the growth axis and their thermal conductivity was calculated from the measurements of thermal diffusivity, heat capacity and density. We have also recorded absorption, fluorescence spectra and measured fluorescence lifetimes as a function of the Tm content, we have found a very attractive fluorescence around the eye-safe wavelength of 1.9 mm which corresponds to a 3F4 → 3H6 transition of Tm3+.

  13. Synthesis, growth and characterization of L-Phenylalaninium methanesulfonate nonlinear optical single crystal

    Science.gov (United States)

    Mangaiyarkarasi, K.; Ravichandran, A. T.; Anitha, K.; Manivel, A.

    2018-03-01

    The titled compound, L-Phenylalaninium methanesulfonate (LPA-MS) was synthesized and grown into single crystals by slow solvent evaporation solution growth technique in aqueous solution containing equimolar concentrations of L-phenylalanine and methanesulfonic acid at room temperature. The grown crystals were subjected to single crystal X-ray diffraction studies. It crystallizes in the monoclinic crystal structure with P21 space group and the unit cell parameters are a = 5.312 (10) Å, b = 8.883 (2) Å and c = 25.830 (7) Å. The functional groups of the LPA-MS crystal were confirmed with FT-IR and FT-Raman analysis. The carbon-hydrogen skeleton was confirmed with 1H NMR and 13C NMR analysis. TG-DTG and DSC studies were carried out to determine the thermal stability of the crystals. The optical transparency ranges were studied through UV-vis-spectroscopy and the crystal was found to be transparent in the visible region. The second Harmonic generation (SHG) efficiency of the grown LPA-MS crystal was measured by the Kurtz-Perry powder technique. The dipolar nature of the L-phenylalaninium methanesulfonate and the presence of the intermolecular hydrogen bonding between the molecules are the vital factors responsible for the existence of SHG activity in the crystal.

  14. Production of organic-semiconductor nanostructures by solid-phase wetting. Guided growth, molecular data storage, and local coadsorption; Erzeugung organischer Halbleiter-Nanostrukturen durch Festphasenbenetzung. Gefuehrtes Wachstum, molekulare Datenspeicherung und lokale Koadsorption

    Energy Technology Data Exchange (ETDEWEB)

    Trixler, Frank

    2007-09-10

    The present thesis treats questions from the interdisciplinary field of nanosciences by studies by means of scanning tunneling microscopy and computer chemistry. The main part of this thesis is the presentation of a novel structure formation process on molecular level. The presented model describes this process by nanocrystals, which show - suspended in a matrix - in contact with a crystal surface a behaviour, which is in spite present solid-state properties (crystalline order) similar to the behaviour of liquid drops in the wetting of surfaces. Starting from this the technological potential of this new process is made accessible.: 1.) Adsorbate structures of a series of organic semiconductors are described for the first time. By this it is additionally shown that by supramolecular solid-phase wetting unsolvable semiconductor molecules can be very simply and under environmental conditions orderedly adsorbed. 2.) An explanation model is developed, by which the hitherto not understandable molecular data storage by means of PTCDA molecules can be theoretically explained and extended to further molecules. 3.) The development of a nanofabrication concept is presented, which allows a local control of the growth of nanostructures. The advance against a classical molecule-for-molecule performed nanostructuration lies therein that by the tip of a scanning tunneling microscope solely the information of growth directions is locally to be brought into the system, the actual formation of the structures however takes place by independently running and by this qualitatively and timely highly efficient growth processes. 4.) A procedure is presented, which allows a local adsorption of molecules to ordered layers within a layer of other molecules and by this makes possible the formation of heterogeneous adsorbate layers.

  15. Plasmonic Nanostructures for Biosensor Applications

    Science.gov (United States)

    Gadde, Akshitha

    Improving the sensitivity of existing biosensors is an active research topic that cuts across several disciplines, including engineering and biology. Optical biosensors are the one of the most diverse class of biosensors which can be broadly categorized into two types based on the detection scheme: label-based and label-free detection. In label-based detection, the target bio-molecules are labeled with dyes or tags that fluoresce upon excitation, indicating the presence of target molecules. Label-based detection is highly-sensitive, capable of single molecule detection depending on the detector type used. One method of improving the sensitivity of label-based fluorescence detection is by enhancement of the emission of the labels by coupling them with metal nanostructures. This approach is referred as plasmon-enhanced fluorescence (PEF). PEF is achieved by increasing the electric field around the nano metal structures through plasmonics. This increased electric field improves the enhancement from the fluorophores which in turn improves the photon emission from the fluorophores which, in turn, improves the limit of detection. Biosensors taking advantage of the plasmonic properties of metal films and nanostructures have emerged an alternative, low-cost, high sensitivity method for detecting labeled DNA. Localized surface plasmon resonance (LSPR) sensors employing noble metal nanostructures have recently attracted considerable attention as a new class of plasmonic nanosensors. In this work, the design, fabrication and characterization of plasmonic nanostructures is carried out. Finite difference time domain (FDTD) simulations were performed using software from Lumerical Inc. to design a novel LSPR structure that exhibit resonance overlapping with the absorption and emission wavelengths of quantum dots (QD). Simulations of a composite Au/SiO2 nanopillars on silicon substrate were performed using FDTD software to show peak plasmonic enhancement at QD emission wavelength

  16. Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications

    Science.gov (United States)

    Sun, Enwei; Cao, Wenwu

    2014-01-01

    In the past decade, domain engineered relaxor-PT ferroelectric single crystals, including (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT), (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) and (1-x-y)Pb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-xPbTiO3 (PIN-PMN-PT), with compositions near the morphotropic phase boundary (MPB) have triggered a revolution in electromechanical devices owing to their giant piezoelectric properties and ultra-high electromechanical coupling factors. Compared to traditional PbZr1-xTixO3 (PZT) ceramics, the piezoelectric coefficient d33 is increased by a factor of 5 and the electromechanical coupling factor k33 is increased from 90%. Many emerging rich physical phenomena, such as charged domain walls, multi-phase coexistence, domain pattern symmetries, etc., have posed challenging fundamental questions for scientists. The superior electromechanical properties of these domain engineered single crystals have prompted the design of a new generation electromechanical devices, including sensors, transducers, actuators and other electromechanical devices, with greatly improved performance. It took less than 7 years from the discovery of larger size PMN-PT single crystals to the commercial production of the high-end ultrasonic imaging probe “PureWave”. The speed of development is unprecedented, and the research collaboration between academia and industrial engineers on this topic is truly intriguing. It is also exciting to see that these relaxor-PT single crystals are being used to replace traditional PZT piezoceramics in many new fields outside of medical imaging. The new ternary PIN-PMN-PT single crystals, particularly the ones with Mn-doping, have laid a solid foundation for innovations in high power acoustic projectors and ultrasonic motors, hinting another revolution in underwater SONARs and miniature actuation devices. This article intends to provide a comprehensive review on the development of relaxor-PT single crystals, spanning material discovery, crystal growth

  17. Development of n- and p-type Doped Perovskite Single Crystals Using Solid-State Single Crystal Growth (SSCG) Technique

    Science.gov (United States)

    2017-10-09

    tried. Among them “n- and p-type doped” BaTiO3 single crystals have been successfully fabricated . And their bi- crystals containing a twin or twist...boundary are also fabricated using diffusion bonding process of two single crystal plates. These results demonstrate that the SSCG (solid-state...or Bridgman method have critical limitations; high production cost and compositional inhomogeneity throughout the crystal. These limitations result

  18. Characterization of Plant Growth under Single-Wavelength Laser Light Using the Model Plant Arabidopsis Thaliana

    KAUST Repository

    Ooi, Amanda

    2016-12-01

    Indoor horticulture offers a promising solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available lighting is suboptimal, therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. Lasers are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Besides, laser beams can be tailored to match the absorption profiles of different plants. We have developed a prototype laser growth chamber and demonstrate that laser-grown plants can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteomic data show that the singlewavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture. Furthermore, stomatal movement partly determines the plant productivity and stress management. Abscisic acid (ABA) induces stomatal closure by promoting net K+-efflux from guard cells through outwardrectifying K+ (K+ out) channels to regulate plant water homeostasis. Here, we show that the Arabidopsis thaliana guard cell outward-rectifying K+ (ATGORK) channel is a direct target for ABA in the regulation of stomatal aperture and hence gas exchange and transpiration. Addition of (±)-ABA, but not the biologically inactive (−)-isomer, increases K+ out channel activity in Vicia faba guard cell protoplast. A similar ABA

  19. Nanostructured Biomaterials and Their Applications

    Directory of Open Access Journals (Sweden)

    Kirsten Parratt

    2013-05-01

    Full Text Available Some of the most important advances in the life sciences have come from transitioning to thinking of materials and their properties on the nanoscale rather than the macro or even microscale. Improvements in imaging technology have allowed us to see nanofeatures that directly impact chemical and mechanical properties of natural and man-made materials. Now that these can be imaged and quantified, substantial advances have been made in the fields of biomimetics, tissue engineering, and drug delivery. For the first time, scientists can determine the importance of nanograins and nanoasperities in nacre, direct the nucleation of apatite and the growth of cells on nanostructured scaffolds, and pass drugs tethered to nanoparticles through the blood-brain barrier. This review examines some of the most interesting materials whose nanostructure and hierarchical organization have been shown to correlate directly with favorable properties and their resulting applications.

  20. Magnetic Nanostructures

    OpenAIRE

    Bennemann, K. H.

    2010-01-01

    Characteristic results of magnetism in small particles and thin films are presented. As a consequence of the reduced atomic coordination in small clusters and thin films the electronic states and density of states modify. Thus magnetic moments and magnetization are affected. In tunnel junctions interplay of magnetism, spin currents and superconductivity are of particular interest. Results are given for single transition metal clusters, cluster ensembles, thin films and tunnel systems. Interes...

  1. Templates for integrated nanofiber growth

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de

    interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. In-situ growth constitutes a very promising strategy for integrating functional nanostructures into device platforms due to the possibility of parallel......-crystalline substrates, such as muscovite mica, on which long, mutually parallel nanofibers are self-assembled upon vapor deposition of the organic material under high vacuum conditions. However, the lack of ability to further process these substrates and for integration of such fragile nanostructures with the necessary......, high-volume integration. Besides such single-crystalline templates, the nanofibers can also be grown on non-crystalline gold surfaces, on which the orientation of the nanofibers can be manipulated by structuring the gold surface prior to p6P deposition. In this work, a novel method for in-situ growth...

  2. Advanced Magnetic Nanostructures

    CERN Document Server

    Sellmyer, David

    2006-01-01

    Advanced Magnetic Nanostructures is devoted to the fabrication, characterization, experimental investigation, theoretical understanding, and utilization of advanced magnetic nanostructures. Focus is on various types of 'bottom-up' and 'top-down' artificial nanostructures, as contrasted to naturally occurring magnetic nanostructures, such as iron-oxide inclusions in magnetic rocks, and to structures such as perfect thin films. Chapter 1 is an introduction into some basic concepts, such as the definitions of basic magnetic quantities. Chapters 2-4 are devoted to the theory of magnetic nanostructures, Chapter 5 deals with the characterization of the structures, and Chapters 6-10 are devoted to specific systems. Applications of advanced magnetic nanostructures are discussed in Chapters11-15 and, finally, the appendix lists and briefly discusses magnetic properties of typical starting materials. Industrial and academic researchers in magnetism and related areas such as nanotechnology, materials science, and theore...

  3. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  4. Structural defect induced peak splitting in gold-copper bimetallic nanorods during growth by single particle spectroscopy.

    Science.gov (United States)

    Thota, Sravan; Chen, Shutang; Zhou, Yadong; Zhang, Yong; Zou, Shengli; Zhao, Jing

    2015-09-21

    A single particle level study of bimetallic nanoparticle growth provides valuable information that is usually hidden in ensemble measurements, helping to improve the understanding of a reaction mechanism and overcome the synthetic challenges. In this study, we use single particle spectroscopy to monitor the changes in the scattering spectra of Au-Cu alloy nanorods during growth. We found that the unique features of the single particle scattering spectra were due to atomic level geometric defects in the nanorods. Electrodynamics simulations have demonstrated that small structural defects of a few atomic layers split the scattering peaks, giving rise to higher order modes, which do not exist in defect-free rods of similar geometry. The study shows that single particle scattering technique is as sensitive as high-resolution electron microscopy in revealing atomic level structural defects.

  5. Synthesis and single crystal growth of perovskite semiconductor CsPbBr3

    Science.gov (United States)

    Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Chen, Zheng; He, Jianle; Zhang, Sen; Chen, Cheng; Luo, Wei

    2018-02-01

    As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has attracted significant attention in recent years. The direct band gap semiconductor CsPbBr3 has a wide band gap of 2.25 eV and high average atomic number (Cs: 55, Pb: 82 and Br: 35), which meet most of the requirements for detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response. However, the growth of large volume CsPbBr3 single crystals remains a challenge. In this paper, the synthesis of CsPbBr3 polycrystalline powders by a chemical co-precipitation method was investigated and the optimum synthesis conditions were obtained. A large CsPbBr3 single crystal of 8 mm diameter and 60 mm length was obtained by a creative electronic dynamic gradient (EDG) method. X-ray diffraction (XRD) patterns and X-ray rocking curve showed that the CsPbBr3 crystal preferentially oriented in the (1 1 0) direction and had a low dislocation density and small residual stress in the crystal. The IR and UV-Vis transmittance and temperature-dependent photoluminescence (PL) spectra showed the crystal had a good basic optical performance. The almost linear current-voltage (I-V) curves implied good ohmic contact between the electrodes and crystal surfaces. The resistivity of the crystal was calculated 109-1010 Ω cm. The above results showed that the quality of the obtained crystal had met the demand of optoelectronic applications.

  6. Nanostructured Materials for Magnetoelectronics

    CERN Document Server

    Mikailzade, Faik

    2013-01-01

    This book provides an up-to-date review of nanometer-scale magnetism and focuses on the investigation of the basic properties of magnetic nanostructures. It describes a wide range of physical aspects together with theoretical and experimental methods. A broad overview of the latest developments in this emerging and fascinating field of nanostructured materials is given with emphasis on the practical understanding and operation of submicron devices based on nanostructured magnetic materials.

  7. Single nanowire resistive nano-heater for highly localized thermo-chemical reactions: localized hierarchical heterojunction nanowire growth.

    Science.gov (United States)

    Yeo, Junyeob; Kim, Gunho; Hong, Sukjoon; Lee, Jinhwan; Kwon, Jinhyeong; Lee, Habeom; Park, Heeseung; Manoroktul, Wanit; Lee, Ming-Tsang; Lee, Bong Jae; Grigoropoulos, Costas P; Ko, Seung Hwan

    2014-12-29

    A single nanowire resistive nano-heater (RNH) is fabricated, and it is demonstrated that the RNH can induce highly localized temperature fields, which can trigger highly localized thermo-chemical reactions to grow hierarchical nanowires directly at the desired specific spot such as ZnO nanowire branch growth on a single Ag nanowire. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Growth rate anisotropy and absorption studies on β-BaB 2O 4 single crystals grown by the top-seeded solution growth technique

    Science.gov (United States)

    Bhatt, Rajeev; Ganesamoorthy, S.; Bhaumik, Indranil; Karnal, A. K.; Wadhawan, V. K.

    2007-03-01

    Beta barium borate (β-BaB2O4; BBO) single crystals have been grown from Na2O flux by the TSSG technique and the observed growth rate anisotropy is reported. The symmetrical conoscopic interference pattern on the c-cut plate confirmed strain-free and optical homogeneity of the crystals. The observed growth habits of as-grown crystals are explained using crystal growth theories. The relative growth rate along different crystallographic directions of BBO can be described by R[100] = R[010] > R[001]. The absorption measurements show a nearly 9 nm shift in fundamental absorption edges in X and Z cut samples. Band gap energies measured were 6.45 and 6.2 eV along the X and Z directions, respectively. The absorption spectra near the fundamental absorption edges (AE) follow Urbach's rule.

  9. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures

    DEFF Research Database (Denmark)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-01-01

    . 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different......A stochastic model was developed for simultaneous growth of low numbers of Listeria monocytogenes and populations of lactic acid bacteria from the aroma producing cultures applied in cottage cheese. During more than two years, different batches of cottage cheese with aroma culture were analysed...

  10. Growth and characterization of 2-amino-4-picolinium 4-aminobenzoate single crystals

    Science.gov (United States)

    Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.

    2010-04-01

    The organic material of 2-amino-4-picolinium 4-aminobenzoate (C 6H 9N 2+·C 7H 6NO 2-) was synthesized and grown as single crystals at room temperature by slow evaporation solution growth technique in the constant temperature bath (±0.01 °C) using ethanol as solvent. The grown crystals were characterized by XRD and FT-IR spectral analyses. The melting point, density, UV-visible spectral studies were carried out for the grown crystals. The theoretical factor group analysis predicts 372 internal modes of vibration and optical modes in the grown title compound. The second harmonic generation (SHG) output of 2-amino-4-picolinium 4-aminobenzoate was recorded by Kurtz-Perry powder technique and it is found to be 355 mV at a given pulse energy of 1.45 mJ/s and for urea the SHG output was 525 mV. The dielectric behaviour of 2-amino-4-picolinium 4-aminobenzoate was investigated with different frequencies and temperatures.

  11. Electrochemical deposition of copper on single-crystal gallium nitride(0001) electrode: nucleation and growth mechanism

    International Nuclear Information System (INIS)

    Zhao, Yu; Deng, Feng-Xiang; Hu, Li-Feng; Liu, Yong-Qiang; Pan, Ge-Bo

    2014-01-01

    Highlights: • The nucleation and growth of Cu electrodeposition on n-GaN was explored. • The Cu deposition commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ . • The deposition process was quasi-reversible and mass transfer limited. • The deposition occurred on the conduction band of n-GaN. - Abstract: The electrodeposition of Cu on n-type single-crystal GaN(0001) electrode from sulfate solution was investigated by electrochemical techniques and scanning electron microscopy. It was found that Cu deposition on GaN(0001) commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ and was quasi-reversible and mass transfer limited. On the basis of Tafel plot, a low exchange current density of ∼ 2.3 × 10 −6 mA cm −2 was calculated. This was mainly due to the limited free electrons in the conduction band of GaN. In addition, the current transient measurements revealed that the deposition process followed the progressive nucleation in 0.5 M H 2 SO 4 + 5 mM CuSO 4 . The instantaneous nucleation was observed only at the large applied potential of −1.1 V

  12. Large-size TlBr single crystal growth and defect study

    Science.gov (United States)

    Zhang, Mingzhi; Zheng, Zhiping; Chen, Zheng; Zhang, Sen; Luo, Wei; Fu, Qiuyun

    2018-04-01

    Thallium bromide (TlBr) is an attractive semiconductor material for fabrication of radiation detectors due to its high photon stopping power originating from its high atomic number, wide band gap and high resistivity. In this paper the vertical Bridgman method was used for crystal growth and TlBr single crystals with diameter of 15 mm were grown. X-ray diffraction (XRD) was used to identify phase and orientation. Electron backscatter diffraction (EBSD) was used to investigate crystal microstructure and crystallographic orientation. The optical and electric performance of the crystal was characterized by infrared (IR) transmittance spectra and I-V measurement. The types of point defects in the crystals were investigated by thermally stimulated current (TSC) spectra and positron annihilation spectroscopy (PAS). Four types of defects, with ionization energy of each defect fitting as follows: 0.1308, 0.1540, 0.3822 and 0.538 eV, were confirmed from the TSC result. The PAS result showed that there were Tl vacancies in the crystal.

  13. Taguchi analysis of parameters for small-diameter single wall carbon nanotube growth

    Directory of Open Access Journals (Sweden)

    DaeJin Kang

    2017-09-01

    Full Text Available Small diameter single wall carbon nanotubes are desirable for various physical and electrical properties of carbon nanotubes. Here, we report the sensitivities of parameters and the optimal conditions for small diameter carbon nanotube growth by chemical vapor deposition (CVD. These results were obtained using the Taguchi method, which is commonly used to find the optimal parameters of various processes. The possible parameter ranges given by the experimental equipment and laboratory conditions, we attempted several times to determine the proper ranges, using photoluminescence (PL imaging to determine the exact positions of suspended carbon nanotubes on the quartz substrates after synthesis. The diameters of the carbon nanotubes were then determined from the radial breathing modes (RBM using Raman spectroscopy with a 785nm wavelength laser. Among the 4 major parameters listed above, we concluded that the temperature was the most significant parameter in determining carbon nanotube diameter, hydrogen flow rate was the second most significant, the ethanol and argon gas flow rate was the third, and finally time was the least significant factor.

  14. Growth Termination and Multiple Nucleation of Single-Wall Carbon Nanotubes Evidenced by in Situ Transmission Electron Microscopy

    DEFF Research Database (Denmark)

    Zhang, Lili; He, Maoshuai; Hansen, Thomas Willum

    2017-01-01

    In order to controllably grow single-wall carbon nanotubes (SWCNTs), a better understanding of the growth processes and how they are influenced by external parameters such as catalyst and gaseous environment is required. Here, we present direct evidence of growth termination of individual SWCNTs...... and successive growth of additional SWCNTs on Co catalyst particles supported on MgO by means of environmental transmission electron microscopy. Such in situ observations reveal the plethora of solid carbon formations at the local scale while it is happening and thereby elucidate the multitude of configurations...... resulting from identical external synthesis conditions, which should be considered in the quest for controlled SWCNT growth. Using CO and a mixture of and H2 as carbon sources, we show that the growth of SWCNTs terminates with a reduced tube−catalyst adhesion strength. Two main reasons for the cessation...

  15. Nanostructured layers of thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Jeffrey J.; Lynch, Jared; Coates, Nelson; Forster, Jason; Sahu, Ayaskanta; Chabinyc, Michael; Russ, Boris

    2018-01-30

    This disclosure provides systems, methods, and apparatus related to thermoelectric materials. In one aspect, a method includes providing a plurality of nanostructures. The plurality of nanostructures comprise a thermoelectric material, with each nanostructure of the plurality of nanostructures having first ligands disposed on a surface of the nanostructure. The plurality of nanostructures is mixed with a solution containing second ligands and a ligand exchange process occurs in which the first ligands disposed on the plurality of nanostructures are replaced with the second ligands. The plurality of nanostructures is deposited on a substrate to form a layer. The layer is thermally annealed.

  16. Fabrication, structural characterization and photoluminescence of Q-1D semiconductor ZnS hierarchical nanostructures.

    Science.gov (United States)

    Zhang, Jun; Yang, Yongdong; Jiang, Feihong; Li, Jianping; Xu, Baolong; Wang, Xichang; Wang, Shumei

    2006-05-28

    Quasi-one-dimensional semiconductor ZnS hierarchical nanostructures have been fabricated by thermal evaporation of a mixture of ZnS nanopowders and Sn powders. Sn nanoparticles are located at or close to the tips of the nanowires (or nanoneedles) and served as the catalyst for quasi-one-dimensional ZnS nanostructure growth by a vapour-liquid-solid mechanism. The morphology and microstructure of the ZnS hierarchical nanostructures were measured by scanning electron microscopy and high-resolution transmission electron microscopy. The results show that a large number of ZnS nanoneedles were formed on the outer shells of a long and straight ZnS axial nanowire. The ZnS axial nanowires grow along the [001] direction, and ZnS nanoneedles are aligned over the surface of the ZnS nanowire in the radial direction. The room temperature photoluminescence spectrum exhibits a UV weak emission centred at 337 nm and one blue emission centred at 436 nm from the as-synthesized single-crystalline semiconductor ZnS hierarchical nanostructures.

  17. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures.

    Science.gov (United States)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-07-02

    A stochastic model was developed for simultaneous growth of low numbers of Listeria monocytogenes and populations of lactic acid bacteria from the aroma producing cultures applied in cottage cheese. During more than two years, different batches of cottage cheese with aroma culture were analysed for pH, lactic acid concentration and initial concentration of lactic acid bacteria. These data and bootstrap sampling were used to represent product variability in the stochastic model. Lag time data were estimated from observed growth data (lactic acid bacteria) and from literature on L. monocytogenes single cells. These lag time data were expressed as relative lag times and included in growth models. A stochastic model was developed from an existing deterministic growth model including the effect of five environmental factors and inter-bacterial interaction [Østergaard, N.B, Eklöw, A and Dalgaard, P. 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different stress levels, was simulated. The simulated growth was subsequently compared to growth of low concentrations (0.4-1.0 CFU/g) of L. monocytogenes in cottage cheese, exposed to similar stresses, and in general a good agreement was observed. In addition, growth simulations were performed using population relative lag time distributions for L. monocytogenes as reported in literature. Comparably good predictions were obtained as for the simulations performed using lag time data for individual cells of L. monocytogenes. Therefore, when lag time data for individual cells are not available, it was suggested that relative lag time distributions for L. monocytogenes can be used as a qualified default assumption when simulating growth of low concentrations of L. monocytogenes. Copyright

  18. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    OpenAIRE

    Fang, Hui

    2012-01-01

    By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  19. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    Directory of Open Access Journals (Sweden)

    Hui Fang

    2012-01-01

    Full Text Available By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  20. Study on shaped single crystal growth and scintillating properties of Bi-doped rare-earth garnets

    Czech Academy of Sciences Publication Activity Database

    Novoselov, A.; Yoshikawa, A.; Nikl, Martin; Solovieva, Natalia; Fukuda, T.

    2005-01-01

    Roč. 40, 4/5 (2005), s. 419-423 ISSN 0232-1300 R&D Projects: GA MŠk(CZ) 1P04ME716 Institutional research plan: CEZ:AV0Z10100521 Keywords : garnet * shaped single crystal growth * luminescent properties * Bi 3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.833, year: 2005

  1. Effects of seed geometry on the crystal growth and the magnetic properties of single grain REBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hwi Joo; Lee, Hee Gyoun [Korea Polytechnic University, Siheung (Korea, Republic of); Park, Soon Dong; Jun, Bung Hyack; Kim, Chan Joong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-09-15

    This study presents that the orientation and the geometry of seed affect on the growth behavior of melt processed single grain REBCO bulk superconductor and its magnetic properties. The effects of seed geometry have been investigated for thin 30mm x 30mm rectangular powder compacts. Single grain REBCO bulk superconductors have been grown successfully by a top seed melt growth method for 8-mm thick vertical thin REBCO slab. Asymmetric structures have been developed at the front surface and at the rear surface of the specimen. Higher magnetic properties have been obtained for the specimen that c-axis is normal to the specimen surface. The relationships between microstructure, grain growth and magnetic properties have been discussed.

  2. Numerical and experimental study of a solid pellet feed continuous Czochralski growth process for silicon single crystals

    Science.gov (United States)

    Anselmo, A.; Prasad, V.; Koziol, J.; Gupta, K. P.

    1993-07-01

    A polysilicon pellets (≅1 mm diameter) feed continuous Czochralski (CCZ) growth process for silicon single crystals is proposed and investigated. Experiments in an industrial puller (14-18 inch diameter crucible) successfully demonstrate the feasibility of this process. The advantages of the proposed scheme are: a steady state growth process, a low aspect ratio melt, uniformity of heat addition and a growth apparatus with single crucible and no baffle(s). The addition of dopant with the solid charge will allow a better control of oxygen concentration leading to crystals of uniform properties and better quality. This paper presents theoretical results on melting of fully and partially immersed silicon spheres and numerical solutions on temperature and flow fields in low aspect ration melts with and without the addition of solid pellets. The theoretical and experimental results obtained thus far show a great promise for the proposed scheme.

  3. Structure and Growth Control of Organic–Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong

    2016-01-01

    Recently, organic–inorganic halide perovskites have sparked tremendous research interest because of their ground‐breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light‐emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high‐quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three‐dimensional large sized single crystals, two‐dimensional nanoplates, one‐dimensional nanowires, to zero‐dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high‐performance (opto)electronic devices. PMID:27812463

  4. Structure and Growth Control of Organic-Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals.

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong; Liang, Ziqi

    2016-04-01

    Recently, organic-inorganic halide perovskites have sparked tremendous research interest because of their ground-breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light-emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high-quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three-dimensional large sized single crystals, two-dimensional nanoplates, one-dimensional nanowires, to zero-dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high-performance (opto)electronic devices.

  5. Growth of large aluminum nitride single crystals with thermal-gradient control

    Science.gov (United States)

    Bondokov, Robert T; Rao, Shailaja P; Gibb, Shawn Robert; Schowalter, Leo J

    2015-05-12

    In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.

  6. Growth of single - crystals of Pb1-x Snx Te by vapor phase transport with the formation of a liquid/solid growth interface

    International Nuclear Information System (INIS)

    An, C.Y.; Bandeira, I.N.

    1985-01-01

    Due to segregation effects single-crystals of Pb 1-x Sn x Te growth by Bridgman techniques have an inhomogeneous composition profile. A vapor phase transport growth process has been developed in order to reduce convective flows. This is due to the very thin melt layer in front of the crystal, that makes convective flows small and solute mixing in the melt very low. By this process single-crystals with 60mm length by 15 mm diameter and a high degree of homogeneity have been grown. A process for determination of the exact composition profile by measurements of the crystal density, for isomorphous alloys of the type A 1-x B x , is also shown. (Author) [pt

  7. Single-cell analysis of S. cerevisiae growth recovery after a sublethal heat-stress applied during an alcoholic fermentation.

    Science.gov (United States)

    Tibayrenc, Pierre; Preziosi-Belloy, Laurence; Ghommidh, Charles

    2011-06-01

    Interest in bioethanol production has experienced a resurgence in the last few years. Poor temperature control in industrial fermentation tanks exposes the yeast cells used for this production to intermittent heat stress which impairs fermentation efficiency. Therefore, there is a need for yeast strains with improved tolerance, able to recover from such temperature variations. Accordingly, this paper reports the development of methods for the characterization of Saccharomyces cerevisiae growth recovery after a sublethal heat stress. Single-cell measurements were carried out in order to detect cell-to-cell variability. Alcoholic batch fermentations were performed on a defined medium in a 2 l instrumented bioreactor. A rapid temperature shift from 33 to 43 °C was applied when ethanol concentration reached 50 g l⁻¹. Samples were collected at different times after the temperature shift. Single cell growth capability, lag-time and initial growth rate were determined by monitoring the growth of a statistically significant number of cells after agar medium plating. The rapid temperature shift resulted in an immediate arrest of growth and triggered a progressive loss of cultivability from 100 to 0.0001% within 8 h. Heat-injured cells were able to recover their growth capability on agar medium after a lag phase. Lag-time was longer and more widely distributed as the time of heat exposure increased. Thus, lag-time distribution gives an insight into strain sensitivity to heat-stress, and could be helpful for the selection of yeast strains of technological interest.

  8. Method to deterministically study photonic nanostructures in different experimental instruments

    NARCIS (Netherlands)

    Husken, B.H.; Woldering, L.A.; Blum, Christian; Tjerkstra, R.W.; Vos, Willem L.

    2009-01-01

    We describe an experimental method to recover a single, deterministically fabricated nanostructure in various experimental instruments without the use of artificially fabricated markers, with the aim to study photonic structures. Therefore, a detailed map of the spatial surroundings of the

  9. Effect of temperature gradient in the solution on spiral growth of YBa2Cu3O7-x bulk single crystals

    International Nuclear Information System (INIS)

    Kanamori, Y.; Shiohara, Y.

    1996-01-01

    Bulk single crystals of Y123 are required to clarify the superconductivity phenomena and develop electronic devices using unique superconductive properties. Only the Solute Rich Liquid endash Crystal Pulling (SRL-CP) method has succeeded in continuous growth of the Y123 single crystal. In this paper, we investigated the growth of Y123 single crystals under different temperature gradients in the solution in order to understand the growth mechanism of Y123. It was revealed that Y123 single crystals grow with a spiral growth mode, which is in good agreement with the BCF theory. copyright 1996 Materials Research Society

  10. Single nucleotide polymorphism of the growth hormone (GH encoding gene in inbred and outbred domestic rabbits

    Directory of Open Access Journals (Sweden)

    Deyana Gencheva Hristova

    2018-03-01

    Full Text Available Taking into consideration that the growth hormone (GH gene in rabbits is a candidate for meat production, understanding the genetic diversity and variation in this locus is of particular relevance. The present study comprised 86 rabbits (Oryctolagus cuniculus divided into 3 groups: New Zealand White (NZW outbred rabbits; first-generation inbred rabbits (F1 and second-generation inbred rabbits (F2. They were analysed by polymerase chain reaction-based restriction fragment length polymorphism method. A 231 bp fragment of the polymorphic site of the GH gene was digested with Bsh1236 restriction enzyme. Single nucleotide polymorphisms for the studied GH locus corresponding to 3 genotypes were detected in the studied rabbit populations: CC, CT and TT. In the synthetic inbred F1 and F2 populations, the frequency of the heterozygous genotype CT was 0.696 and 0.609, respectively, while for the homozygous CC genotype the frequency was lower (0.043 and 0.000, and respective values for the homozygous TT genotype were 0.261 and 0.391. This presumed a preponderance of the T allele (0.609 and 0.696 over the C allele (0.391 and 0.304 in these groups. In outbred rabbits, the allele frequencies were 0.613 (allele C and 0.387 (allele Т; consequently, the frequency of the homozygous CC genotype was higher than that of the homozygous TT genotype (0.300 vs. 0.075. Observed heterozygosity for the GH gene was higher than expected, and the result was therefore a negative inbreeding coefficient (Fis=–0.317 for outbred NZW rabbits; –0.460 for inbred F1 and –0.438 for inbred F2, indicating a sufficient number of heterozygous forms in all studied groups of rabbits. The application of narrow inbreeding by breeding full sibs in the synthetic population did not cause a rapid increase in homozygosity.

  11. CAFFEINE ATTENUATES ACUTE GROWTH HORMONE RESPONSE TO A SINGLE BOUT OF RESISTANCE EXERCISE

    Directory of Open Access Journals (Sweden)

    Bo-Hun Wu

    2010-06-01

    Full Text Available The purpose of this study was to investigate the effects of caffeine consume on substrate metabolism and acute hormonal responses to a single bout of resistance exercise (RE. Ten resistance-trained men participated in this study. All subjects performed one repetition maximum (1RM test and then performed two protocols: caffeine (CAF, 6 mg·kg-1 and control (CON in counter balanced order. Subjects performed RE (8 exercises, 3 sets of 10 repetitions at 75% of 1RM after caffeine or placebo ingestion one hour prior to RE. Blood samples collected prior to treatment ingestion (pre-60, immediately prior to RE (pre-exe, and 0, 15, 30 min post to RE (P0, P15, P30 for analysis of insulin, testosterone, cortisol, growth hormone, glucose, free fatty acid and lactic acid. Each experiment was separated by seven days. In this study, statistical analysis of a two-way analysis of variance (treatment by time with repeated measures was applied. After ingesting caffeine, the concentrations of free fatty acid (pre- exe, P0, P15, P30 in CAF were significantly higher than CON (p < 0.05. Additionally, the responses of GH (P0, P15, P30 in CAF were significantly lower than CON (p < 0.05, whereas the concentrations of insulin, testosterone and cortisol were not different between CAF and CON (p < 0.05 after RE. The results of this study indicated that caffeine ingestion prior to RE might attenuate the response of GH. This effect might be caused by the elevation in blood FFA concentration at the beginning of RE

  12. A theoretical model describing the one-dimensional growth of single crystals on free sustained substrates

    Science.gov (United States)

    Ye, Ziran; Wang, Ke; Lu, Chenxi; Jin, Ying; Sui, Chenghua; Yan, Bo; Gao, Fan; Cai, Pinggen; Lv, Bin; Li, Yun; Chen, Naibo; Sun, Guofang; Xu, Fengyun; Ye, Gaoxiang

    2018-03-01

    We develop a theoretical model that interprets the growth mechanism of zinc (Zn) crystal nanorods on a liquid substrate by thermal evaporation. During deposition, Zn atoms diffuse randomly on an isotropic and quasi-free sustained substrate, the nucleation of the atoms results in the primary nanorod (or seed crystal) growth. Subsequently, a characteristic one-dimensional atomic aggregation is proposed, which leads to the accelerating growth of the crystal nanorod along its preferential growth direction until the growth terminates. The theoretical results are in good agreement with the experimental findings.

  13. Hydrogen adsorption in carbon nanostructures compared

    NARCIS (Netherlands)

    Schimmel, H.G.; Nijkamp, M.G.; Kearley, G.J.; Rivera, A.; de Jong, K.P.; Mulder, F.M.

    2004-01-01

    Recent reports continue to suggest high hydrogen storage capacities for some carbon nanostructures due to a stronger interaction between hydrogen and carbon. Here the interaction of hydrogen with activated charcoal, carbon nanofibers, single walled carbon nanotubes (SWNT), and electron beam ‘opened’

  14. Multiscale modelling of nanostructures

    International Nuclear Information System (INIS)

    Vvedensky, Dimitri D

    2004-01-01

    Most materials phenomena are manifestations of processes that are operative over a vast range of length and time scales. A complete understanding of the behaviour of materials thereby requires theoretical and computational tools that span the atomic-scale detail of first-principles methods and the more coarse-grained description provided by continuum equations. Recent efforts have focused on combining traditional methodologies-density functional theory, molecular dynamics, Monte Carlo methods and continuum descriptions-within a unified multiscale framework. This review covers the techniques that have been developed to model various aspects of materials behaviour with the ultimate aim of systematically coupling the atomistic to the continuum descriptions. The approaches described typically have been motivated by particular applications but can often be applied in wider contexts. The self-assembly of quantum dot ensembles will be used as a case study for the issues that arise and the methods used for all nanostructures. Although quantum dots can be obtained with all the standard growth methods and for a variety of material systems, their appearance is a quite selective process, involving the competition between equilibrium and kinetic effects, and the interplay between atomistic and long-range interactions. Most theoretical models have addressed particular aspects of the ordering kinetics of quantum dot ensembles, with far fewer attempts at a comprehensive synthesis of this inherently multiscale phenomenon. We conclude with an assessment of the current status of multiscale modelling strategies and highlight the main outstanding issues. (topical review)

  15. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution.......Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... The growth mechanisms as well as the roles of different components in the catalyst were studied in situ using environmental transmission electron microscopy and infrared spectroscopy. On the basis of the understanding of carbon nanotube growth mechanisms, an MgO-supported FeCu catalyst was prepared...

  16. Phonon engineering for nanostructures.

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, Sylvie (Stanford University); Friedmann, Thomas Aquinas; Sullivan, John Patrick; Peebles, Diane Elaine; Hurley, David H. (Idaho National Laboratory); Shinde, Subhash L.; Piekos, Edward Stanley; Emerson, John Allen

    2010-01-01

    Understanding the physics of phonon transport at small length scales is increasingly important for basic research in nanoelectronics, optoelectronics, nanomechanics, and thermoelectrics. We conducted several studies to develop an understanding of phonon behavior in very small structures. This report describes the modeling, experimental, and fabrication activities used to explore phonon transport across and along material interfaces and through nanopatterned structures. Toward the understanding of phonon transport across interfaces, we computed the Kapitza conductance for {Sigma}29(001) and {Sigma}3(111) interfaces in silicon, fabricated the interfaces in single-crystal silicon substrates, and used picosecond laser pulses to image the thermal waves crossing the interfaces. Toward the understanding of phonon transport along interfaces, we designed and fabricated a unique differential test structure that can measure the proportion of specular to diffuse thermal phonon scattering from silicon surfaces. Phonon-scale simulation of the test ligaments, as well as continuum scale modeling of the complete experiment, confirmed its sensitivity to surface scattering. To further our understanding of phonon transport through nanostructures, we fabricated microscale-patterned structures in diamond thin films.

  17. Nuclear spins in nanostructures

    International Nuclear Information System (INIS)

    Coish, W.A.; Baugh, J.

    2009-01-01

    We review recent theoretical and experimental advances toward understanding the effects of nuclear spins in confined nanostructures. These systems, which include quantum dots, defect centers, and molecular magnets, are particularly interesting for their importance in quantum information processing devices, which aim to coherently manipulate single electron spins with high precision. On one hand, interactions between confined electron spins and a nuclear-spin environment provide a decoherence source for the electron, and on the other, a strong effective magnetic field that can be used to execute local coherent rotations. A great deal of effort has been directed toward understanding the details of the relevant decoherence processes and to find new methods to manipulate the coupled electron-nuclear system. A sequence of spectacular new results have provided understanding of spin-bath decoherence, nuclear spin diffusion, and preparation of the nuclear state through dynamic polarization and more general manipulation of the nuclear-spin density matrix through ''state narrowing.'' These results demonstrate the richness of this physical system and promise many new mysteries for the future. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Direct growth of NiCo2O4 nanostructures on conductive substrates with enhanced electrocatalytic activity and stability for methanol oxidation.

    Science.gov (United States)

    Qian, Lei; Gu, Li; Yang, Li; Yuan, Hongyan; Xiao, Dan

    2013-08-21

    In this report, NiCo2O4 nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo2O4 on stainless steel (SS) had a high surface area (119 m(2) g(-1)) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo2O4 showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co3O4 synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity, large surface area of NiCo2O4 and the fast ion/electron transport in the electrode and at the electrolyte-electrode interface. This is important for further development of high performance non-platinum electrocatalysts for application in direct methanol fuel cells.

  19. Mg-catalyzed autoclave synthesis of aligned silicon carbide nanostructures.

    Science.gov (United States)

    Xi, Guangcheng; Liu, Yankuan; Liu, Xiaoyan; Wang, Xiaoqing; Qian, Yitai

    2006-07-27

    In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature (600 degrees C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as-synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/microm, respectively.

  20. Nanowires, nanostructures and devices fabricated therefrom

    Science.gov (United States)

    Majumdar, Arun; Shakouri, Ali; Sands, Timothy D.; Yang, Peidong; Mao, Samuel S.; Russo, Richard E.; Feick, Henning; Weber, Eicke R.; Kind, Hannes; Huang, Michael; Yan, Haoquan; Wu, Yiying; Fan, Rong

    2005-04-19

    One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as "nanowires", include single-crystalline homostructures as well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire (LOHN) and a coaxial heterostructure nanowire (COHN).

  1. Computational analysis of heat transfer, thermal stress and dislocation density during resistively Czochralski growth of germanium single crystal

    Science.gov (United States)

    Tavakoli, Mohammad Hossein; Renani, Elahe Kabiri; Honarmandnia, Mohtaram; Ezheiyan, Mahdi

    2018-02-01

    In this paper, a set of numerical simulations of fluid flow, temperature gradient, thermal stress and dislocation density for a Czochralski setup used to grow IR optical-grade Ge single crystal have been done for different stages of the growth process. A two-dimensional steady state finite element method has been applied for all calculations. The obtained numerical results reveal that the thermal field, thermal stress and dislocation structure are mainly dependent on the crystal height, heat radiation and gas flow in the growth system.

  2. Growth and PhysioChemical Properties of Second-Order Nonlinear Optical L-Threonine Single Crystals

    Directory of Open Access Journals (Sweden)

    G. Ramesh Kumar

    2009-01-01

    Full Text Available The present aim of the paper is to grow and to study the various properties of L-threonine amino acid single crystal in various aspects. Crystal growth of L-threonine single crystals has been carried out with the help of crystallization kinetics. pH and deuteration effects on the properties of the grown crystals have been studied and the results presented in a lucid manner. The various second-order NLO parameters were evaluated using anharmonic oscillator model. Particle and ion irradiation effects on structural, optical, and surface properties of the crystals have also been studied in detail.

  3. Crystal growth, structure analysis and characterisation of 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sankari, R. Siva, E-mail: sivasankari.sh@act.edu.in [Department of Physics, Agni College of Technology, Thalambur, Chennai-603103 (India); Perumal, Rajesh Narayana [Department of Physics, SSN College of Engineering, Kalavakkam, Chennai-603110 (India)

    2014-04-24

    Single crystal of dielectric material 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid has been grown by slow evaporation solution growth method. The grown crystal was harvested in 25 days. The crystal structure was analyzed by Single crystal X - ray diffraction. UV-vis-NIR analysis was performed to examine the optical property of the grown crystal. The thermal property of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The dielectric measurements were carried out and the dielectric constant was calculated and plotted at all frequencies.

  4. Growth and study of barium oxalate single crystals in agar gel

    Indian Academy of Sciences (India)

    Unknown

    by X-ray powder diffractometry, infrared spectroscopy, thermogravimetric and differential thermal analysis. An attempt is ... Quality. Transparent, opaque. Opaque. Size. 17 × 4 × 2, 4 × 3 × 2 and 4 mm diameter 4 mm diameter. Figure 1. Dendritic growth of barium oxalate. interstitial and spherulitic growth well inside the gel on.

  5. Synthesis of In2O3 nanostructures with different morphologies as potential supercapacitor electrode materials

    Science.gov (United States)

    Tuzluca, Fatma Nur; Yesilbag, Yasar Ozkan; Ertugrul, Mehmet

    2018-01-01

    In this study performed using a chemical vapor deposition (CVD) system, one-dimensional (1-D) single crystal indium oxide (In2O3) nanotowers, nanobouqets, nanocones, and nanowires were investigated as a candidate for a supercapacitor electrode material. These nanostructures were grown via Vapor-Liquid-Solid (VLS) and Vapor-Solid (VS) mechanisms according to temperature differences (1000-600 °C). The morphologies, growth mechanisms and crystal structures of these 1-D single crystal In2O3 nanostructures were defined by Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Diffraction (XRD) and Raman Spectroscopy analyses. The elemental analyses of the nanostructures were carried out by energy dispersive X-Ray Spectroscopy (EDS); they gave photoluminescence (PL) spectra with 3.39, 2.65, and 1.95 eV band gap values, corresponding to 365 nm, 467 nm, and 633 wavelengths, respectively. The electrochemical performances of these 1-D single crystal In2O3 nanostructures in an aqueous electrolyte solution (1 M Na2SO4) were determined by Cyclic Voltammetry (CV), Galvanostatic Charge Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) analyses. According to GCD measurements at 0.04 mA cm-2 current density, areal capacitance values were 10.1 mF cm-2 and 6.7 mF cm-2 for nanotowers, 12.5 mF cm-2 for nanobouquets, 4.9 mF cm-2 for nanocones, and 16.6 mF cm-2 for nanowires. The highest areal capacitance value was observed in In2O3 nanowires, which retained 66.8% of their initial areal capacitance after a 10000 charge-discharge cycle, indicating excellent cycle stability.

  6. Enhanced structural stability of DNA origami nanostructures by graphene encapsulation

    International Nuclear Information System (INIS)

    Matković, Aleksandar; Vasić, Borislav; Pešić, Jelena; Gajić, Radoš; Prinz, Julia; Bald, Ilko; Milosavljević, Aleksandar R

    2016-01-01

    We demonstrate that a single-layer graphene replicates the shape of DNA origami nanostructures very well. It can be employed as a protective layer for the enhancement of structural stability of DNA origami nanostructures. Using the AFM based manipulation, we show that the normal force required to damage graphene encapsulated DNA origami nanostructures is over an order of magnitude greater than for the unprotected ones. In addition, we show that graphene encapsulation offers protection to the DNA origami nanostructures against prolonged exposure to deionized water, and multiple immersions. Through these results we demonstrate that graphene encapsulated DNA origami nanostructures are strong enough to sustain various solution phase processing, lithography and transfer steps, thus extending the limits of DNA-mediated bottom-up fabrication. (paper)

  7. Surface nanostructuring by ion-induced localized plasma expansion in zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    El-Said, A. S., E-mail: elsaid@kfupm.edu.sa, E-mail: a.s.el-said@hzdr.de [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden (Germany); Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Centre for Theoretical Physics, British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); Djebli, M. [Theoretical Physics Laboratory, Faculty of Physics USTHB, B.P. 32 Bab Ezzour, 16079 Algiers (Algeria)

    2014-06-09

    Creation of hillock-like nanostructures on the surface of zinc oxide single crystals by irradiation with slow highly charged ions is reported. At constant kinetic energy, the nanostructures were only observed after irradiation with ions of potential energies above a threshold between 19.1 keV and 23.3 keV. The size of the nanostructures increases as a function of potential energy. A plasma expansion approach is used to explain the nanostructures creation. The calculations showed that the surface nanostructures became taller with the increase of ionic temperature. The influence of charged cluster formation and the relevance of their polarity are discussed.

  8. Study on ECR dry etching and selective MBE growth of AlGaN/GaN for fabrication of quantum nanostructures on GaN (0001) substrates

    International Nuclear Information System (INIS)

    Oikawa, Takeshi; Ishikawa, Fumitaro; Sato, Taketomo; Hashizume, Tamotsu; Hasegawa, Hideki

    2005-01-01

    This paper attempts to form AlGaN/GaN quantum wire (QWR) network structures on patterned GaN (0001) substrates by selective molecular beam epitaxy (MBE) growth. Substrate patterns were prepared along - and -directions by electron cyclotron resonance assisted reactive-ion beam etching (ECR-RIBE) process. Selective growth was possible for both directions in the case of GaN growth, but only in the -direction in the case of AlGaN growth. A hexagonal QWR network was successfully grown on a hexagonal mesa pattern by combining the -direction and two other equivalent directions. AFM observation confirmed excellent surface morphology of the grown network. A clear cathodoluminescence (CL) peak coming from the embedded AlGaN/GaN QWR structure was clearly identified

  9. Growth and study of some gel grown group II single crystals of iodate

    Indian Academy of Sciences (India)

    Unknown

    Page 1 ... Abstract. Single crystals of calcium iodate and barium iodate were grown by simple gel technique by single diffusion method. The optimum conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of the reactants etc. Crystals having ...

  10. Quantum Dot-Based Hybrid Nanostructures and Energy Transfer on the Nanoscale for Single- and Multi-Photon Imaging and Cancer Diagnostics

    Science.gov (United States)

    Nabiev, Igor

    2017-01-01

    An ideal single-photon (1P) or multiphoton fluorescent nanoprobe should combine a nanocrystal with the largest possible 1P or two-photon (2P) absorption cross section and the smallest possible highly specific recognition molecules conjugated with the nanoparticle in an oriented manner. However, the conditions used for conjugation of typical recognition molecules (conventional antibodies, Abs) with nanoparticles often provoke their unfolding and/or yield nanoprobes with irregular orientation of Abs on the nanoparticle surface. Conjugation of smaller Ab fragments, such as single-domain antibodies (sdAbs), with quantum dots (QDs) in an oriented manner can be considered as an attractive approach to engineering of ultrasmall diagnostic nanoprobes. QDs conjugated to 13-kDa sdAbs derived from camelid IgG or streptavidin have been used as efficient 1P or 2P excitation probes for imaging of cancer markers. The 2P absorption cross sections (TPACSs) for some conjugates are higher than 49,000 GM (Goeppert-Mayer units), which is close to the theoretical value calculated for CdSe QDs and considerably exceeds that of organic dyes. A further step in advanced QD-based cancer diagnostics has been made through implementation of efficient FRET-based imaging with 2P excitation, which has been demonstrated for double immunostaining complexes formed on the surface of cancer cells from sdAb-QD conjugates (donor) and a combination of monoclonal Abs and secondary antibodies labeled with the AlexaFluor dye (acceptor). The proposed approach permits obtaining an exceptional contrast of 2P imaging of cancer biomarkers without any contribution of cell and tissue autofluorescence in the recorded images.

  11. Quantum Dot-Based Hybrid Nanostructures and Energy Transfer on the Nanoscale for Single- and Multi-Photon Imaging and Cancer Diagnostics

    International Nuclear Information System (INIS)

    Nabiev, Igor

    2017-01-01

    An ideal single-photon (1P) or multiphoton fluorescent nanoprobe should combine a nanocrystal with the largest possible 1P or two-photon (2P) absorption cross section and the smallest possible highly specific recognition molecules conjugated with the nanoparticle in an oriented manner. However, the conditions used for conjugation of typical recognition molecules (conventional antibodies, Abs) with nanoparticles often provoke their unfolding and/or yield nanoprobes with irregular orientation of Abs on the nanoparticle surface. Conjugation of smaller Ab fragments, such as single-domain antibodies (sdAbs), with quantum dots (QDs) in an oriented manner can be considered as an attractive approach to engineering of ultrasmall diagnostic nanoprobes. QDs conjugated to 13-kDa sdAbs derived from camelid IgG or streptavidin have been used as efficient 1P or 2P excitation probes for imaging of cancer markers. The 2P absorption cross sections (TPACSs) for some conjugates are higher than 49,000 GM (Goeppert–Mayer units), which is close to the theoretical value calculated for CdSe QDs and considerably exceeds that of organic dyes. A further step in advanced QD-based cancer diagnostics has been made through implementation of efficient FRET-based imaging with 2P excitation, which has been demonstrated for double immunostaining complexes formed on the surface of cancer cells from sdAb–QD conjugates (donor) and a combination of monoclonal Abs and secondary antibodies labeled with the AlexaFluor dye (acceptor). The proposed approach permits obtaining an exceptional contrast of 2P imaging of cancer biomarkers without any contribution of cell and tissue autofluorescence in the recorded images. (paper)

  12. The crystalline quality distribution in CdZnTe single crystal correlated to the interface shape during growth

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, M.; Rotter, S.; Gafni, G. (Soreq Nuclear Research Center, Yavne (Israel)); Roth, M. (School of Applied Science and Technology, Hebrew Univ. of Jerusalem (Israel))

    1992-02-01

    Crystalline quality of CdZnTe single crystals grown by the vertical gradient freeze (VGF) method has been evaluated using the double crystal rocking curve (DCRC) analysis and etch pits density (EPD) measurements. The full width at half maximum (HWHM) values of the DCRCs vary within 40% while the EPD values range from 2 to 8 x 10{sup 4} cm{sup -2} along the crystal growth axis. Best results are obtained for the central part of the crystals, where the growth interface exhibits a nearly planar shape. The results obtained have been used for practical implications with regard to the use of CdZnTe crystals as a substrate material for HgCdTe thin films growth. (orig.).

  13. Sputtering an exterior metal coating on copper enclosure for large-scale growth of single-crystalline graphene

    DEFF Research Database (Denmark)

    Luo, Birong; Caridad, José M; Whelan, Patrick Rebsdorf

    2017-01-01

    We show the suppression of nucleation density in chemical vapor deposited graphene through the use of a sputtered metal coating on the exterior of a copper catalyst enclosure, resulting in the growth of sub-centimeter scale single crystal graphene domains and complete elimination of multilayer...... growth. The sputtered coating suppresses nucleation density by acting as both a diffusion barrier and as a sink for excess carbon during the growth, reducing the carbon concentration in the interior of the enclosure. Field effect mobility of hBN-templated devices fabricated from graphene domains grown...... in this way show room temperature carrier mobilities of 12 000 cm2 V−1 s−1 and an absence of weak localization at low temperature. These results indicate a very low concentration of line and point defects in the grown films, which is further supported by Raman and transmission electron microscopic...

  14. Injection moulding antireflective nanostructures

    DEFF Research Database (Denmark)

    Christiansen, Alexander Bruun; Clausen, Jeppe Sandvik; Mortensen, N. Asger

    We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used in an inject......We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used...... in an injection moulding process, to fabricate the antireflective surfaces. The cycle-time was 35 s. The injection moulded structures had a height of 125 nm, and the visible spectrum reflectance of injection moulded black polypropylene surfaces was reduced from 4.5±0.5% to 2.5±0.5%. The gradient of the refractive...

  15. Self-assembled nanostructures

    CERN Document Server

    Zhang, Jin Z; Liu, Jun; Chen, Shaowei; Liu, Gang-yu

    2003-01-01

    Nanostructures refer to materials that have relevant dimensions on the nanometer length scales and reside in the mesoscopic regime between isolated atoms and molecules in bulk matter. These materials have unique physical properties that are distinctly different from bulk materials. Self-Assembled Nanostructures provides systematic coverage of basic nanomaterials science including materials assembly and synthesis, characterization, and application. Suitable for both beginners and experts, it balances the chemistry aspects of nanomaterials with physical principles. It also highlights nanomaterial-based architectures including assembled or self-assembled systems. Filled with in-depth discussion of important applications of nano-architectures as well as potential applications ranging from physical to chemical and biological systems, Self-Assembled Nanostructures is the essential reference or text for scientists involved with nanostructures.

  16. Nanostructured CNx (0

    NARCIS (Netherlands)

    Bongiorno, G; Blomqvist, M; Piseri, P; Milani, P; Lenardi, C; Ducati, C; Caruso, T; Rudolf, P; Wachtmeister, S; Csillag, S; Coronel, E

    Nanostructured CNx thin films were prepared by supersonic cluster beam deposition (SCBD) and systematically characterized by transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The

  17. Synthesis, characterization and luminescence properties of zinc oxide nanostructures

    Science.gov (United States)

    Khan, Aurangzeb

    Zinc oxide (ZnO) represents an important semiconductor material due to its wideband gap (3.37 eV at room temperature), large exciton binding energy (60 meV), high optical gain, and luminescence as well as piezoelectric properties [1]. From the 1960s, ZnO thin films have been extensively studied because of their applications as sensors, transducers and catalysts [2]. Since a few decades, one-dimensional nanostructures have become the focus point in nanoscience and nanotechnology. Nanostructures are considered to have unique physical, chemical, catalytic and optical properties that are profoundly different from their bulk counterparts. Since the discovery of carbon nanotubes (CNTs) in 1991, a string of research activities led to the growth and characterization of nanostructures of various materials including semiconductors such as Si, Ge and also compound semiconductors such as InP, GaAs, GaN and ZnO. ZnO is a versatile material and has shown potential for the synthesis of various types of nanostructures such as nanocombs, nanorings, nanohelices/nanosprings, nanobelts, nanowires and nanocages under specific growth conditions and probably has the richest family of nanostructures among all materials, both in structure and properties. This dissertation presents the synthesis, characterization and luminescence properties of ZnO nanostructures with the development of a PVD system. The nanostructures of ZnO are synthesized on various kinds of substrates such as Silicon, Sapphire and Alumina. We have synthesized a large family of nanostructures such as nanowires, nanorods, nanobelts, aligned nanorods, nanosheets, nanospheres, nanocombs, microspheres, hexagons etc. The nanostructures are then characterized by SEM, EDX, TEM, HRTEM, XRD, Raman Spectroscopy, PL and CL. From the characterization of the materials, we observed that these nanostructures are of good crystalline quality. PL and CL spectra reveal that all the nanostructures emit a ˜380 nm (UV) usually called the near

  18. Progress and Prospect of the Growth of Wide-Band-Gap Group III Nitrides: Development of the Growth Method for Single-Crystal Bulk GaN

    Science.gov (United States)

    Amano, Hiroshi

    2013-05-01

    Thin films of III-V compound semiconductors such as GaAs and InP can be grown on native substrates, whereas such growth was difficult for group III nitride semiconductors. Despite this drawback, scientists have gradually become able to use the functions of group III nitride semiconductors by growing their thin films on non-native substrates such as sapphire and Si substrates. With the continuously increasing demand for the conservation and generation of energy, bulk substrates of group III nitride semiconductors are highly expected to maximize their potential. In this report, I review the current status of the growth methods for bulk GaN single crystals used for substrates as well as summarize the characteristics of blue light-emitting diodes (LEDs), heterojunction field-effect transistors (HFETs), and photovoltaic cells on GaN substrates.

  19. Crystal growth and scintillation properties of Lu substituted CeBr.sub.3./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Ito, T.; Yokota, Y.; Kurosawa, S.; Král, Robert; Kamada, K.; Pejchal, Jan; Ohashi, Y.; Yoshikawa, A.

    2016-01-01

    Roč. 452, Oct (2016), s. 65-68 ISSN 0022-0248. [American Conference on Crystal Growth and Epitaxy /20./ (ACCGE) / 17th Biennial Workshop on Organometallic Vapor Phase Epitaxy (OMVPE) / 2nd 2D Electronic Materials Symposium. Big Sky, MT, 02.08.2015-07.08.2015] Institutional support: RVO:68378271 Keywords : radiation * halides * scintillator materials * crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.751, year: 2016

  20. Formation of gallium arsenide nanostructures in Pyrex glass.

    Science.gov (United States)

    Howlader, Matiar M R; Zhang, Fangfang; Deen, M Jamal

    2013-08-09

    In this paper, we report on a simple, low-cost process to grow GaAs nanostructures of a few nm diameter and ∼50 nm height in Pyrex glass wafers. These nanostructures were grown by sequential plasma activation of GaAs and Pyrex glass surfaces using a low-temperature hybrid plasma bonding technology in air. Raman analyses of the activated surfaces show gallium oxide and arsenic oxide, as well as suppressed non-bridging oxygen with aluminate and boroxol chains in glass. The flow of alkaline ions toward the cathode and the replacement of alkaline ions by Ga and As ions in glass result in the growth of GaAs nanostructures in nanopores/nanoscratches in glass. These nanopores/nanoscratches are believed to be the origin of the growth of the nanostructures. It was found that the length of the GaAs nanostructures may be controlled by an electrostatic force. Cross-sectional observation of the bonded interface using high-resolution transmission electron microscopy confirms the existence of the nanostructures. A possible application of the nanostructures in glass is a filtration system for biomolecules.

  1. Crystal growth and scintillation properties of Pr-doped SrI2 single crystals

    Science.gov (United States)

    Yokota, Yuui; Ito, Tomoki; Yoshino, Masao; Yamaji, Akihiro; Ohashi, Yuji; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2018-04-01

    Pr-doped SrI2 (Pr:SrI2) single crystals with various Pr concentrations were grown by the halide-micro-pulling-down (H-μ-PD) method, and the scintillation properties were investigated. Pr1%:SrI2 single crystal with high transparency could be grown by the H-μ-PD method while Pr2, 3 and 5%:SrI2 single crystals included some cracks and opaque parts. In the photoluminescence spectrum of the Pr1%:SrI2 single crystal, an emission peak originated from the Pr3+ ion was observed around 435 nm while the radioluminescence spectra showed an emission peak around 535 nm for the undoped SrI2 and Pr:SrI2 single crystals. Light yields of Pr1, 2, 3 and 5%:SrI2 single crystals under γ-ray irradiation were 7700, 8700, 7200 and 6700 photons/MeV, respectively. Decay times of Pr1 and 2%:SrI2 single crystals under γ-ray irradiation were 55.9 and 35.0 ns of the fast decay component, and 435 and 408 ns of the slow decay component, respectively.

  2. Growth and characterization of lead-free (K,Na)NbO3-based piezoelectric single crystals

    International Nuclear Information System (INIS)

    Liu, Hairui

    2016-01-01

    Lead-free piezoelectric materials have received increasing attention in the last decade, driven by environmental issues and health concerns. Of considerable interest is the (K,Na)NbO 3 (KNN)-based system, which possesses a relatively high Curie temperature and good piezoelectric properties. Abundant publications on KNN-based polycrystalline ceramics increased the interest in studying their single-crystalline form, based on two major concerns. The first concern refers to the negative role of grain interactions on the electromechanical response. The second concern deals with domain engineering. The relationship between external electric field direction, crystallographic orientation, and spontaneous polarization vectors for a specific structure can be more readily established in single crystals and thus offers a pathway for an in-depth understanding of fundamental mechanism and potential applications. The exciting enhancement of both piezoelectric and ferroelectric response in lead-based single crystals also encourages the further exploration of KNN-based piezoelectric crystals, as they possess the same perovskite structure. The main goal of this thesis is to find possible approaches for improved electromechanical properties in KNN-based piezoelectric single crystals. In Chapter 2, the current development of KNN-based single crystals as piezoelectrics is reviewed, following a short introduction of fundamental knowledge on piezoelectrics and ferroelectrics. Both submerged-seed solution growth and top-seeded solution growth techniques were employed to produce single crystals, as described detailed in Chapter 3. Emphasis is subsequently placed on issues of the crystal growth process, effective methods to enhance electrical properties, and crystallographic orientation-dependent electrical properties in Li-, Ta-, and/or Sb-substituted KNN single crystals. The main conclusions from the crystal growth aspect are presented in Chapter 4 and can be summarized as follows: (i

  3. Single crystal growth and X-ray structure analysis of non-peripheral octahexyl phthalocyanine

    Science.gov (United States)

    Ohmori, Masashi; Nakano, Chika; Higashi, Takuya; Miyano, Tetsuya; Tohnai, Norimitsu; Fujii, Akihiko; Ozaki, Masanori

    2016-07-01

    The single-crystal structure of metal-free non-peripheral octahexyl-substituted phthalocyanine (C6PcH2) has been investigated by single-crystal X-ray structure analysis. Two types of C6PcH2 single crystal, bulk and needle crystals, were separately grown by controlling the recrystallization conditions. The structures of the two types of crystal were determined, and were found to be completely different, that is, C6PcH2 exhibits structural polymorphism. It has been clarified that the C6PcH2 microcrystals in thin films used in previously reported electronic devices have the needle structure.

  4. Ultrasensitive electrochemical detection of microRNA-21 combining layered nanostructure of oxidized single-walled carbon nanotubes and nanodiamonds by hybridization chain reaction.

    Science.gov (United States)

    Liu, Lingzhi; Song, Chao; Zhang, Zhang; Yang, Juan; Zhou, Lili; Zhang, Xing; Xie, Guoming

    2015-08-15

    Measurement of microRNA (miRNA) levels in body fluids is a crucial tool for the early diagnosis and prognosis of cancers. In this study, we developed an electrochemical assay to detect miRNA-21 by fabricating the electrode with layer-by-layer assembly of oxidized single-walled carbon nanotubes and nanodiamonds. Tetrahedron-structured probes with free-standing probe on the top served as receptors to hybridize with target miRNA directly. The probes were immobilized on the deposited gold nanoparticles through a well-established strong Au-S bond. The electrochemical signal was mainly derived from an ultrasensitive pattern by combining hybridization chain reaction with DNA-functionalized AuNPs, which provided DNAzyme to catalyze H2O2 reduction. Differential pulse voltammetry was applied to record the electrochemical signals, which was increased linearly with the target miRNA-21, and the linear detection range was 10 fM to 1.0 nM. The limit of detection reached 1.95 fM (S/N=3), and the proposed biosensor exhibited good reproducibility and stability, as well as high sensitivity. Hence, this biosensor has a promising potential in clinical application. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Seed crystal in growth of KDP single crystal for optical harmonic generation

    International Nuclear Information System (INIS)

    Shimomura, Osamu

    1985-01-01

    As for the crystal growth of KDP for optical harmonic generation, the employment of (101) seed crystal plate could reduce crystal growth period in comparison with the employment of conventional (001) seed crystal plate except the case of low phase matching angle. This paper describes seed crystal in the case of types I and II of phase matching, evaluation of minimum crystal volume to cut necessary volume crystal plate for optical harmonic generation in the case of types I and II for (001) and (101) crystal plates, results and discussion of numerical analysis of KDP crystal growth for the above-mentioned cases and experimental results of actual KDP crystal growth. It was clarified from these examinations that the use of a (101) crystal plate as a seed showed faster crystal growth regardless of theta m, a phase matching angle. It was also shown that the minimum crystal volume to cut the necessary volume crystal for optical harmonic generation became less by employing a (101) crystal plate than employing a (001) crystal in the case of high phase matching angle, namely theta m > 23.7 0 for type I and theta m > 11.6 0 for type II. Example calculations showed that 54.4 % of crystal growth period for type I and 33.8 % of that for type II was needed for the (101) seed crystal plate in comparison with the case of the (001) seed crystal plate. It was speculated that this conclusion might be applicable also for DKDP or ADP crystals growth. (Takagi, S.)

  6. Structural and optical properties of Cd2+ ion on the growth of sulphamic acid single crystals

    Science.gov (United States)

    Rajyalakshmi, S.; Rao, Valluru Srinivasa; Reddy, P. V. S. S. S. N.; Krishna, V. Y. Rama; Samatha, K.; Rao, K. Ramachandra

    2016-05-01

    Transparent single crystals of Cadmium doped Sulphamic acid (SA) was grown by Conventional slow evaporation solution technique (SEST) which had the size of 13 × 8 × 7 mm3. The grown single crystals have been characterized using single crystal X-ray diffraction UV-visible Spectral studies and Second harmonic generation (SHG) efficiency and the results were discussed. The lattice parameters of the grown Cd2+ ion doped SA crystal are confirmed by single crystal X-ray diffraction and belong to orthorhombic system. Optical transmittance of the crystal was recorded using UV-vis NIR spectrophotometer with its lower cut off wavelength around 259nm. SHG measurements indicate that the SHG efficiency of the grown Cd2+ ion doped SA crystal at a fundamental wavelength of 1064 nm is approximately equal to KDP.

  7. Growth and Characterization of PDMS-Stamped Halide Perovskite Single Microcrystals

    NARCIS (Netherlands)

    Khoram, P.; Brittman, S.; Dzik, W.I.; Reek, J.N.H.; Garneett, E.C.

    2016-01-01

    Recently, halide perovskites have attracted considerable attention for optoelectronic applications, but further progress in this field requires a thorough understanding of the fundamental properties of these materials. Studying perovskites in their single-crystalline form provides a model system for

  8. Normal Growth in PKU Patients Under Low-Protein Diet in a Single-Center Cross-Sectional Study.

    Science.gov (United States)

    Matic, Jana; Zeltner, Nina A; Häberle, Johannes

    2018-02-25

    Dietary phenylalanine restriction in phenylketonuria (PKU) patients is usually mandatory in order to prevent cognitive impairment. The influence of a low-protein diet on growth has raised concerns in families and caregivers. This paper aims to investigate the growth in PKU patients treated with a low-protein diet including supplementation of amino acids and other nutrients according to standard protocols.We performed a single-center, cross-sectional study on growth in pediatric PKU patients (n = 51) treated with low-protein diet over a 20-month period. Height of healthy siblings (n = 44) and target height, calculated based on parents' height, served as controls.No statistically significant differences were found comparing mean height z-scores between patients and siblings (p = 0.261). Patients PKU patients treated with low-protein diet can achieve normal growth with patients making up the leeway after puberty. While prepubertal patients were shorter than expected based on their target height, older patients were within their expected target height. This study indicates that current practice of low-protein diet in PKU patients allows normal growth.

  9. Growth Temperature Dependence of Morphology of GaN Single Crystals in the Na-Li-Ca Flux Method

    Science.gov (United States)

    Wu, Xi; Hao, Hangfei; Li, Zhenrong; Fan, Shiji; Xu, Zhuo

    2018-02-01

    In this paper, the effect of growth temperature on the morphology and transparency of the GaN crystals obtained by the Li-Ca-added Na Flux method was studied. Addition of Li-Ca was attempted to control the growth habit and further improve transparency of GaN crystals. The samples with wurtzite structure of GaN were confirmed by the x-ray powder diffraction analysis. GaN single crystal with maximum size of about 6 mm was grown at 750°C. As the growth temperature was increased from 700°C to 850°C, the morphology of the crystals changed from pyramid to prism, and their surfaces became smooth. It was found that high growth temperature was beneficial to obtain a transparent crystal, but the evaporation of sodium would suppress its further growth. The E 2 (high) mode in the Raman spectra was at 568 cm-1, and the full-width at half-maximum values of this peak for the crystals obtained at 700°C, 750°C, 800°C, and 850°C were 7.5 cm-1, 10.3 cm-1, 4.4 cm-1, and 4.0 cm-1, respectively. It indicates that all the crystals are stress free and the transparent crystal grown at high temperature has high structural quality or low impurity concentrations.

  10. Inhibition of microbial growth on air cathodes of single chamber microbial fuel cells by incorporating enrofloxacin into the catalyst layer.

    Science.gov (United States)

    Liu, Weifeng; Cheng, Shaoan; Sun, Dan; Huang, Haobin; Chen, Jie; Cen, Kefa

    2015-10-15

    The inevitable growth of aerobic bacteria on the surface of air cathodes is an important factor reducing the performance stability of air cathode single-chamber membrane-free microbial fuel cells (MFCs). Thus searching for effective methods to inhibit the cathodic microbial growth is critical for the practical application of MFCs. In this study, enrofloxacin (ENR), a broad spectrum fluoroquinolone antibiotic, was incorporated into the catalyst layer of activated carbon air cathodes (ACACs) to inhibit the cathodic microbial growth. The biomass content on ACACs was substantially reduced by 60.2% with ENR treatment after 91 days of MFCs operation. As a result of the inhibited microbial growth, the oxygen reduction catalytic performance of the ENR treated ACACs was much stable compared to the fast performance decline of the untreated control. Consequently, a quite stable electricity production was obtained for the MFCs with the ENR treated ACACs, in contrast with a 22.5% decrease in maximum power density of the MFCs with the untreated cathode. ENR treatment of ACACs showed minimal effects on the anode performance. These results indicate that incorporating antibiotics into ACACs should be a simple and effective strategy to inhibit the microbial growth and improve the long-term stability of the performance of air cathode and the electricity production of MFCs. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Single-Step Seeded-Growth of Graphene Nanoribbons (GNRs) via Plasma-Enhanced Chemical Vapor Deposition (PECVD)

    Science.gov (United States)

    Hsu, C.-C.; Yang, K.; Tseng, W.-S.; Li, Yiliang; Li, Yilun; Tour, J. M.; Yeh, N.-C.

    One of the main challenges in the fabrication of GNRs is achieving large-scale low-cost production with high quality. Current techniques, including lithography and unzipped carbon nanotubes, are not suitable for mass production. We have recently developed a single-step PECVD growth process of high-quality graphene sheets without any active heating. By adding some substituted aromatic as seeding molecules, we are able to rapidly grow GNRs vertically on various transition-metal substrates. The morphology and electrical properties of the GNRs are dependent on the growth parameters such as the growth time, gas flow and species of the seeding molecules. On the other hand, all GNRs exhibit strong infrared and optical absorption. From studies of the Raman spectra, scanning electron microscopic images, and x-ray/ultraviolet photoelectron spectra of these GNRs as functions of the growth parameters, we propose a model for the growth mechanism. Our findings suggest that our approach opens up a pathway to large-scale, inexpensive production of GNRs for applications to supercapacitors and solar cells. This work was supported by the Grubstake Award and NSF through IQIM at Caltech.

  12. Vicinal surfaces for functional nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tegenkamp, Christoph [Institut fuer Festkoerperphysik, Gottfried Wilhelm Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)], E-mail: tegenkamp@fkp.uni-hannover.de

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF{sub 2}, MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  13. Low-dimensional II-VI oxide-based semiconductor nanostructure photodetectors for light sensing

    Science.gov (United States)

    Yu, Jae Su; Ko, Yeong Hwan; Nagaraju, Goli

    2015-01-01

    Low-dimensional II-VI oxide-based semiconductor nanostructure photodetectors for light sensing are described. Depending on the absorption edge and energy bandgap of the nanostructured materials, the detection wavelength range can be controlled. The physical properties of the fabricated nanostructures are investigated. The p-n junction property of n-ZnO and p-CuO nanostructures is obtained. This growth of the ZnO nanorod arrays on CuO nanostructures may be useful for photodetection applications. The NiO/ZnO nanostructures are also synthesized. Metal-semiconductor-metal (MSM) type photodetectors are fabricated by integrating the oxide-based (i.e., ZnO and CuO) semiconductor nanostructures. Using the solution-based ZnO seed layer, the UV MSM type photodetectors with the vertically-aligned ZnO nanorod arrays are also fabricated. Their photoresponse characteristics are evaluated in a specific spectral range.

  14. Novel Single Nucleotide Polymorphisms of the Insulin-Like Growth Factor-I Gene and Their Associations with Growth Traits in Common Carp (Cyprinus carpio L.

    Directory of Open Access Journals (Sweden)

    Xiu Feng

    2014-12-01

    Full Text Available Insulin-like growth factor-I (IGF-I plays an important role in the growth and development of vertebrates. To study polymorphisms of IGF-I, we screened a total of 4555 bp of genomic sequences in four exons and partial introns for the discovery of single nucleotide polymorphism (SNP in common carp (Cyprinus carpio. Three SNPs (g.3759T>G, g.7627T>A and g.7722T>C in intron 2 and a nonsynonymous SNP (g.7892C>T in exon 3 were identified in a pilot population including random parents and their progenies. 289 progenies were further genotyped for studying possible associations between genotypes or combined genotypes and growth traits. The results showed that the locus g.7627T>A was significantly associated with body weight and body length, and fish with genotype AA had a mean body weight 5.9% higher than those with genotype TT. No significant associations were observed between genotypes of other loci and growth traits. However, when both g.7627T>A and g.7722T>C were considered, the combined genotype TT/TT was extremely associated with the lowest values of body length and body weight and the highest K value in comparison with other diplotypes (p < 0.01. These results suggest that genotype AA at g.7627T>A and its combined genotypes with alleles from another locus have positive effects on growth traits, which would be a candidate molecular marker for further studies in marker-assisted selection in common carp.

  15. Effects of Pratylenchus vulnus and Xiphinema index singly and combined on vine growth of Vitis vinifera.

    Science.gov (United States)

    Pinochet, J; Raski, D J; Goheen, A C

    1976-10-01

    Inoculation of 'Thompson Seedless' grapevines with 500 Xiphinerna index or 1,000 Pratylenchus vulnus alone or in combination suppressed vine shoot and root growth under greenhouse conditions. Pratytenchus vulnus caused greater stunting of roots than X. index. Each nematode species inhibited top growth about equally. Concomitant inoculations caused greater stunting of tops and roots than did inoculations of either nematode species alone. Differences in growth between inoculated and control plants increased with exposure time. Pratylenchus vulnus competed with and gradually superseded in numbers an established population of X. index. Both species reproduced on 'Thompson Seedless' roots, but P. vulnus increased to a much higher level than did X. index. The increase of P. vulnus, together with extensive damage, proves its pathogenicity to grapevines.

  16. Hydrothermal synthesis and influence of later heat treatment on the structural evolution, optical and electrical properties of nanostructured α-MoO3 single crystals

    Science.gov (United States)

    Badr, A. M.; El-Anssary, E. H.; Elshaikh, H. A.; Afify, H. H.

    2017-12-01

    In the current study, α-MoO3 nanocrystals were successfully synthesized from ammonium heptamolybdate tetrahydrate using a simple hydrothermal route. The influence of calcination temperature on the structural, optical and electrical properties was systematically investigated for the MoO3 powder products. The XRD results were analyzed for these powders, revealing the formation of a mixed phase (β- and α-MoO3) at calcination temperatures ranging from 350 °C–450 °C, and hence a residual monoclinic phase still exists in the samples at the calcination temperature of 450 °C. Subsequently, the mixed phase was completely converted to a pure single phase of α-MoO3 at a calcination temperature of 500 °C. The optical properties of the MoO3 powders were investigated using the transformed diffuse reflectance technique according to Kubelka–Munk theory. For such a powder product, the results of the optical measurements demonstrated the realization of indirect and direct allowed transitions at the spectral ranges 3.31–3.91 eV and 3.66–4.27 eV, respectively. The indirect- and direct-allowed band-gaps of the MoO3 products were found to increase from 2.69–3.12 eV and from 3.43–3.64 eV, respectively, by increasing the calcination temperature from 350 °C–600 °C. The MoO3 powders calcined at different temperatures were converted into five dense tablets for performing the electrical measurements. These measurements were carried out at different working temperatures using a system operating under high vacuum conditions. The results revealed that the dc-conductivity of such a tablet typically increases by more than five orders of magnitude with an increase in the working temperature from 77–300 K. These results also demonstrated a high dependence of dc-conductivity on the calcination temperature for the MoO3 products. The dc-conductivity as a function of the operating temperature revealed the presence of at least three different electrical conduction

  17. Single crystal growth and neutron study of Bi-2212 high temperature superconductor

    International Nuclear Information System (INIS)

    Gu, G.D.; Miles, P.A.; Russell, G. J.; Ivanov, A.; Koshizuka, N.; Kennedy, S.J.

    1999-01-01

    Full text: Many physical properties of the cuprate high temperature superconductors appear to defy the conventional (one-electron) theory of metals. The neutron diffraction and inelastic neutron scattering of the high T c single crystals can provides incisive information about collective magnetic excitations which is required to guide the development of new theories incorporating strong electron correlations. For lack of the suitably large single crystals, inelastic neutron scattering measurements have thus far proven possible for only two of the many families of high temperature superconductors, La 2-x Sr x CuO 4 and YBa 2 Cu 3 O x . While the magnetic pronounced differences that have hampered a unified description of the spin dynamics in the cuprates. In particular, a sharp resonant spin excitation dominates the spectrum in the superconducting state of YBa 2 Cu 3 0 x , but is not found in La 2-x Sr x CuO 4 . We have successfully grown large size Bi-2212 single crystals up to 10*5*1.2 mm 3 by floating zone method, and have studied neutron diffraction and neutron scattering in the single crystals. The Neutron diffraction of the single crystals shows that the crystals are high quality. Here we report the discovery of a magnetic resonance peak in the superconducting state of a third high temperature superconductor of Bi-2212 single crystal by modern neutron optics. The discovery provides evidence of the generality of this unusual phenomenon among the cuprates and greatly extends the empirical basis for its theoretical description. The magnetic resonance peak in Bi-2212 single crystals rules out the possibility or chemical parameters peculiar to YBCO superconductor. Rather, it is an intrinsic feature of the copper oxides whose explanation must be in an integral part of any theory of high temperature superconductivity

  18. Hydrothermal growth of beryl single crystals and morphology of their singular faces

    International Nuclear Information System (INIS)

    Dem'yanets, L.N.; Ivanov-Shits, A.K.; Gajnutdinov, R.V.

    2006-01-01

    The surface morphology of the best developed faces of emerald and red beryl monocrystals grown from high-temperature hydrothermal solutions has been studied by atomic force microscopy. The results attest to dislocation-mediated layer-by-layer growth of the faces. Using experimentally determined growth front profiles, the fractal dimensions D Fp and D Fa of the faces are evaluated to be 1.1-1.4. These values indicate that the surfaces studied have a fractal character and can be investigated using elements of fractal theory [ru

  19. A novel low-temperature chemical solution route for straight and dendrite-like ZnO nanostructures

    International Nuclear Information System (INIS)

    Zhang Hui; Du Ning; Wu Jianbo; Ma, Xiangyang; Yang Deren; Zhang Xiaobin; Yang Zhiqing

    2007-01-01

    The straight and dendrite-like growths of ZnO have been completely and simply controlled by the status of ZnO seed instead of surfactant, template, oriented attachment, and ZnO buffer layer on the substrate in the chemical reaction synthesis of ZnO nanostructures. The monodisperse ZnO seeds, which are prepared by in situ quickly injecting the cool mixed zinc acetate and potassium hydrate ethanol solution into the hot matrix aqueous solution of zinc nitrate hydrate and diethylenetriamine at 95 deg. C, improve the straight growth and lots of uniform, straight, and single-crystalline ZnO nanorods with about 20-30 nm in diameter and 300 nm in length are achieved. While, the aggregated ZnO seeds, which are prepared by dropwise adding potassium hydrate ethanol solution into zinc acetate ethanol solution at 60 deg. C for 3 h, result in the dendrite-like growth and the bur-like ZnO nanostructures consisting of hundreds of nanorods with about 30-50 nm in diameter and several micrometers in length are formed. Furthermore, the approach presented here provides a simple, low-cost, environmental-friendly and high efficiency route to synthesize the high quality ZnO nanorods and bur-like ZnO nanostructures

  20. Formation of novel assembled silver nanostructures from polyglycol solution

    International Nuclear Information System (INIS)

    Zhang Jie; Liu Ke; Dai Zhihui; Feng Yuying; Bao Jianchun; Mo Xiangyin

    2006-01-01

    This paper described a simple and mild chemical reduction approach to prepare novel silver nanostructures with different morphologies. Dendritic silver nanostructure was obtained by a fast reduction reaction using hydrazine as a reducing agent in aqueous solution of polyglycol, while both the zigzag and linear Ag nanostructures were slowly assembled using polyglycol as a reducing agent. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and field emission scanning electron microscopy (FE-SEM) were used to characterize the obtained silver nanostructures. Fourier transform infrared absorption (FT-IR) spectra were recorded to show that there exists a certain coordination of the oxygen atoms in the polyglycol with Ag + ions in aqueous solution of the AgNO 3 /polyglycol. Furthermore, the examination of the morphologies of the products obtained at different stages of the reaction of Ag + ions with polyglycol revealed that such a coordination is of utmost importance for the formation of the silver nanostructures, namely polyglycol provided lots of active sites for the coordination, nucleation, growth and serves as backbones for directing the assembly of the metal particles formed. The formation mechanism of the dendritic silver nanostructure was called a coordination-reduction-nucleation-growth-fractal growth process. The strong surface plasmon absorption bands at 470 nm for the zigzag silver and at 405 nm for the dendritic silver were found

  1. Growth and Neurodevelopmental Outcomes of Extremely Low Birth Weight Infants: A Single Center’s Experience

    Directory of Open Access Journals (Sweden)

    Yung-Chieh Lin

    2011-12-01

    Conclusion: ELBW infants have a high incidence of growth and developmental delay at corrected age of 2 years, particularly in male infants or those with BW less than 750 g. This study reveals that ELBW infants require well predischarge planning and postdischarge follow-up.

  2. Investigation on the bulk growth of α-LiIO 3 single crystals and the ...

    Indian Academy of Sciences (India)

    2017-07-26

    Jul 26, 2017 ... (a) Solubility of LiIO3 in aqueous solvent, (b) spurious crystals at the bottom of the growth vessel and (c) the harvested spurious crystals. ..... 20. Small spot. 25. 8–9. Big spot with crack parts of the grown crystal. As LiIO3 is an indirect bandgap material, the optical bandgap (Eg) has been estimated from the.

  3. Growth of compact arrays of optical quality single crystalline ZnO ...

    Indian Academy of Sciences (India)

    Wintec

    relative concentration, 1) and again decreases for higher values of seed particle densities (up to relative concentra- tion, 10 has been shown). Much higher value of I(002)/I(101) for 5 h grown nanorod arrays compared to 3.5 h grown rods is expected for obvious reason since longer growth time results in better alignment.

  4. In situ monitoring of single-wall carbon nanotube laser assisted growth

    NARCIS (Netherlands)

    Haluška, M.; Bellouard, Y.; Burgt, Y. van de; Dietzel, A.H.

    2010-01-01

    Laser assisted catalytic chemical vapor deposition has recently emerged as an attractive method for locally growing carbon nanotubes (CNTs) in a cold wall reactor. So far, reported laser assisted CNT growth has been carried out without insitu process monitoring. This has made it difficult to control

  5. Growth of n-alkane films on a single-crystal substrate

    DEFF Research Database (Denmark)

    Wu, Z. U.; Ehrlich, S. N.; Matthies, B.

    2001-01-01

    The structure and growth mode of alkane films (n-C/sub n/H/sub 2n+2/; n=4, 6, 7) adsorbed on a Ag(111) surface have been investigated by synchrotron X-ray scattering. New models are proposed for the butane (n=4) and hexane (n=6) monolayer and butane bilayer structures. Specular reflectivity scans...

  6. Growth and study of barium oxalate single crystals in agar gel

    Indian Academy of Sciences (India)

    Barium oxalate was grown in agar gel at ambient temperature. The effect of various parameters like gel concentration, gel setting time and concentration of the reactants on the growth of these crystals was studied. Prismatic platy shaped spherulites and dendrites were obtained. The grown crystals were characterized by ...

  7. Multispectral absorptance from large-diameter InAsSb nanowire arrays in a single epitaxial growth on silicon

    Science.gov (United States)

    Robson, Mitchell; Azizur-Rahman, Khalifa M.; Parent, Daniel; Wojdylo, Peter; Thompson, David A.; LaPierre, Ray R.

    2017-12-01

    Vertical III-V nanowires are capable of resonant absorption at specific wavelengths by tuning the nanowire diameter, thereby exceeding the absorption of equivalent thin films. These properties may be exploited to fabricate multispectral infrared (IR) photodetectors, directly integrated with Si, without the need for spectral filters or vertical stacking of heterostructures as required in thin film devices. In this study, multiple InAsSb nanowire arrays were grown simultaneously on Si by molecular beam epitaxy with nanowire diameter controlled by the nanowire period (spacing between nanowires). This is the first such study of patterned InAsSb nanowires where control of nanowire diameter and multispectral absorption are demonstrated. The antimony flux was used to control axial and radial growth rates using a selective-area catalyst-free growth method, achieving large diameters, spanning 440–520 nm, which are necessary for optimum IR absorption. Fourier transform IR spectroscopy revealed IR absorptance peaks due to the HE11 resonance of the nanowire arrays in agreement with optical simulations. Due to the dependence of the HE11 resonance absorption on nanowire diameter, multispectral absorption was demonstrated in a single material system and a single epitaxial growth step without the need for bandgap tuning. This work demonstrates the potential of InAsSb nanowires for multispectral photodetectors and sensor arrays in the short-wavelength IR region.

  8. Three-dimensional oriented attachment growth of single-crystal pre-perovskite PbTiO3 hollowed fibers

    KAUST Repository

    Zhao, Ruoyu

    2017-12-11

    Hollowed single-crystal pre-perovskite PbTiO fibers (PP-PTF) were successfully synthesized via a polyvinyl alcohol (PVA) assisted hydrothermal process. The as-prepared PP-PTF were characterized to be 0.3-1 μm in diameter and tens of micrometers in length by adjusting the concentration of PVA to 0.8 g L. Microstructure characterization of the samples at different reaction times revealed that PP-PTF were formed via a three-dimensional (3D) hierarchical oriented attachment (OA) growth process. The initial growth units were determined to be single-crystal pre-perovskite PbTiO fibers with a diameter of 10-20 nm. Zeta potential measurement suggested that the main driving force of the OA process is the surface electrostatic force, which is induced by the incompletely bonded Pb and O atomic layers on the surface of the {110} plane. Moreover, molecular dynamics simulations have been employed to reveal a stable configuration of the initial pre-perovskite PbTiO growth units, agreeing well with the experimental results.

  9. Growth of optical-quality anthracene crystals doped with dibenzoterrylene for controlled single photon production

    Energy Technology Data Exchange (ETDEWEB)

    Major, Kyle D., E-mail: kyle.major11@imperial.ac.uk; Lien, Yu-Hung; Polisseni, Claudio; Grandi, Samuele; Kho, Kiang Wei; Clark, Alex S.; Hwang, J.; Hinds, E. A., E-mail: ed.hinds@imperial.ac.uk [Centre for Cold Matter, Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2015-08-15

    Dibenzoterrylene (DBT) molecules within a crystalline anthracene matrix show promise as quantum emitters for controlled, single photon production. We present the design and construction of a chamber in which we reproducibly grow doped anthracene crystals of optical quality that are several mm across and a few μm thick. We demonstrate control of the DBT concentration over the range 6–300 parts per trillion and show that these DBT molecules are stable single-photon emitters. We interpret our data with a simple model that provides some information on the vapour pressure of DBT.

  10. Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

    International Nuclear Information System (INIS)

    Prakash, J. Thomas Joseph; Kumararaman, S.

    2008-01-01

    Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV-vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications

  11. Cavity Pull Rod: Device to Promote Single Crystal Growth from the Melt

    Science.gov (United States)

    Goldsby, Jon (Inventor)

    2017-01-01

    A pull rod for use in producing a single crystal from a molten alloy is provided that includes an elongated rod having a first end and a second end, a first cavity defined at the first end and a second cavity defined at the first end and in communication with the first cavity. The first cavity receives the molten alloy and the second cavity vents a gas from the molten alloy to thereby template a single crystal when the pull rod is dipped into and extracted from the molten alloy.

  12. Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam (India); Baby, C. [Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai (India); Gopalakrishnan, R. [Crystal Research Lab, Department of Physics, Anna University, Chennai (India)

    2016-09-15

    Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

  13. Freestanding nanostructures via reactive ion beam angled etching

    Directory of Open Access Journals (Sweden)

    Haig A. Atikian

    2017-05-01

    Full Text Available Freestanding nanostructures play an important role in optical and mechanical devices for classical and quantum applications. Here, we use reactive ion beam angled etching to fabricate optical resonators in bulk polycrystalline and single crystal diamond. Reported quality factors are approximately 30 000 and 286 000, respectively. The devices show uniformity across 25 mm samples, a significant improvement over comparable techniques yielding freestanding nanostructures.

  14. Synthesis and characterization of hybrid nanostructures

    Directory of Open Access Journals (Sweden)

    Taleb Mokari

    2011-05-01

    Full Text Available There has been significant interest in the development of multicomponent nanocrystals formed by the assembly of two or more different materials with control over size, shape, composition, and spatial orientation. In particular, the selective growth of metals on the tips of semiconductor nanorods and wires can act to couple the electrical and optical properties of semiconductors with the unique properties of various metals. Here, we outline our progress on the solution-phase synthesis of metal-semiconductor heterojunctions formed by the growth of Au, Pt, or other binary catalytic metal systems on metal (Cd, Pb, Cu-chalcogenide nanostructures. We show the ability to grow the metal on various shapes (spherical, rods, hexagonal prisms, and wires. Furthermore, manipulating the composition of the metal nanoparticles is also shown, where PtNi and PtCo alloys are our main focus. The magnetic and electrical properties of the developed hybrid nanostructures are shown.

  15. Magnetic anisotropy of (Ge,Mn) nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Jain, A; Jamet, M; Barski, A; Devillers, T; Yu, I-S; Porret, C; Gambarelli, S; Maurel, V; Desfonds, G; Jacquot, J F, E-mail: abhinav.jain@cea.fr [Institut Nanosciences et Cryogenie, CEA-UJF, F-38054, Grenoble (France)

    2011-04-01

    We present a correlation between structural and magnetic properties of different (Ge,Mn) nanostructures grown on Ge(001) and Ge(111) substrates. Thin films of Ge{sub 1-x}Mn{sub x} were grown by low temperature molecular beam epitaxy to favor the out-of-equilibrium growth. Depending on the growth conditions crystalline or amorphous (Ge,Mn) nanocolumns have been observed on Ge(001) substrates. The magnetic properties were probed by superconducting quantum interference device (SQUID), vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR). With the help of these complementary techniques (SQUID and EPR), magnetic anisotropy in these nanostructures has been investigated and different anisotropy constants were calculated.

  16. Selective Functionalization of Tailored Nanostructures

    NARCIS (Netherlands)

    Slingenbergh, Winand; Boer, Sanne K. de; Cordes, Thorben; Browne, Wesley R.; Feringa, Ben L.; Hoogenboom, Jacob P.; Hosson, Jeff Th.M. De; Dorp, Willem F. van

    2012-01-01

    The controlled positioning of nanostructures with active molecular components is of importance throughout nanoscience and nanotechnology. We present a novel three-step method to produce nanostructures that are selectively decorated with functional molecules. We use fluorophores and nanoparticles to

  17. Growth of Single- and Bilayer ZnO on Au(111) and Interaction with Copper

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xingyi; Yao, Kun; Sun, Keju; Li, Wei-Xue; Lee, Junseok; Matranga, Christopher

    2013-05-02

    The stoichiometric single- and bi-layer ZnO(0001) have been prepared by reactive deposition of Zn on Au(111) and studied in detail with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. Both single- and bi-layer ZnO(0001) adopt a planar, graphite-like structure similar to freestanding ZnO(0001) due to the weak van der Waals interactions dominating their adhesion with the Au(111) substrate. At higher temperature, the single-layer ZnO(0001) converts gradually to bi-layer ZnO(0001) due to the twice stronger interaction between two ZnO layers than the interfacial adhesion of ZnO with Au substrate. It is found that Cu atoms on the surface of bi-layer ZnO(0001) are mobile with a diffusion barrier of 0.31 eV, and likely to agglomerate and form nanosized particles at low coverages; while Cu atoms tend to penetrate a single layer of ZnO(0001) with a barrier of 0.10 eV, resulting in a Cu free surface.

  18. Nanostructured materials in potentiometry.

    Science.gov (United States)

    Düzgün, Ali; Zelada-Guillén, Gustavo A; Crespo, Gastón A; Macho, Santiago; Riu, Jordi; Rius, F Xavier

    2011-01-01

    Potentiometry is a very simple electrochemical technique with extraordinary analytical capabilities. It is also well known that nanostructured materials display properties which they do not show in the bulk phase. The combination of the two fields of potentiometry and nanomaterials is therefore a promising area of research and development. In this report, we explain the fundamentals of potentiometric devices that incorporate nanostructured materials and we highlight the advantages and drawbacks of combining nanomaterials and potentiometry. The paper provides an overview of the role of nanostructured materials in the two commonest potentiometric sensors: field-effect transistors and ion-selective electrodes. Additionally, we provide a few recent examples of new potentiometric sensors that are based on receptors immobilized directly onto the nanostructured material surface. Moreover, we summarize the use of potentiometry to analyze processes involving nanostructured materials and the prospects that the use of nanopores offer to potentiometry. Finally, we discuss several difficulties that currently hinder developments in the field and some future trends that will extend potentiometry into new analytical areas such as biology and medicine.

  19. Micromachining with Nanostructured Cutting Tools

    CERN Document Server

    Jackson, Mark J

    2013-01-01

    The purpose of the brief is to explain how nanostructured tools can be used to machine materials at the microscale.  The aims of the brief are to explain to readers how to apply nanostructured tools to micromachining applications. This book describes the application of nanostructured tools to machining engineering materials and includes methods for calculating basic features of micromachining. It explains the nature of contact between tools and work pieces to build a solid understanding of how nanostructured tools are made.

  20. Atomic mechanism for the growth of wafer-scale single-crystal graphene: theoretical perspective and scanning tunneling microscopy investigations

    Science.gov (United States)

    Niu, Tianchao; Zhang, Jialin; Chen, Wei

    2017-12-01

    Chemical vapor deposition (CVD) is the most promising approach for producing low-cost, high-quality, and large area graphene. Revealing the graphene growth mechanism at the atomic-scale is of great importance for realizing single crystal graphene (SCG) over wafer scale. Density functional theoretical (DFT) calculations are playing an increasingly important role in revealing the structure of the most stable carbon species, understanding the evolution processes, and disclosing the active sites. Scanning tunneling microscopy (STM) is a powerful surface characterization tool to illustrate the real space distribution and atomic structures of growth intermediates during the CVD process. Combining them together can provide valuable information to improve the atomically controlled growth of SCG. Starting from a basic concept of the substrate effect on realizing SCG, this review covers the progress made in theoretical investigations on various carbon species during graphene growth on different transition metal substrates, in the STM study of the structural intermediates on transition metal surfaces, and in synthesizing graphene nanoribbons with atomic-precise width and edge structure, ending with a perspective on the future development of 2D materials beyond graphene.

  1. On-line study of growth kinetics of single hyphae of Aspergillus oryzae in a flow-through cell

    DEFF Research Database (Denmark)

    Christiansen, Torben; Spohr, Anders Bendsen; Nielsen, Jens Bredal

    1999-01-01

    Using image analysis the growth kinetics of the single hyphae of the filamentous fungus Aspergillus oryzae has been determined on-line in a flow-through cell at different glucose concentrations in the range from 26 mg L-1 to 20 g L-1. The tip extension rate of the individual hyphae can be described...... with saturation type kinetics with respect to the length of the hyphae. The maximum tip extension rate is constant for all hyphae measured at the same glucose concentration, whereas the saturation constant for the hyphae varies significantly between the hyphae even within the same hyphal element. When apical...... branching occurs, it is observed that the tip extension rate decreases temporarily. The number of branches formed on a hypha is proportional to the length of the hypha that exceeds a certain minimum length required to support the growth of a new branch. The observed kinetics has been used to simulate...

  2. Single-walled carbon nanotubes: a nano-specific enhancer of cellular growth in LB culture

    International Nuclear Information System (INIS)

    Zhao Jinming; Yang Xiafeng; Zhao Yun; Huang Qing; Li Jiang; Lu Min

    2012-01-01

    We conducted a study to characterize the antimicrobial properties of SWNTs to B.subtilis in a saline solution or in a LB culture. Dimensions and the antibacterial ability of SWNTs in a saline solution were different from those in a LB culture. Transmission and scanning electron microscopes were used to characterize the SWNTs structure with and without LB culture. The antibacterial ability of SWNTs was affected by the environment of bacterial growth. The antibacterial mechanism of SWNTs was studied,too. (authors)

  3. Growth and optical properties of RE-doped ternary rubidium lead chloride single crystals

    Czech Academy of Sciences Publication Activity Database

    Král, Robert; Nitsch, Karel; Babin, Vladimir; Šulc, J.; Jelínková, H.; Yokota, Y.; Yoshikawa, A.; Nikl, Martin

    2013-01-01

    Roč. 36, č. 2 (2013), s. 214-220 ISSN 0925- 3467 R&D Projects: GA MŠk LH12150 Institutional support: RVO:68378271 Keywords : rubidium lead chloride * crystal growth * micro-pulling-down method * rare earth doping * luminescence Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.075, year: 2013 http://www.sciencedirect.com/science/article/pii/S0925346713004710

  4. Superhydrophobic multi-scale ZnO nanostructures fabricated by chemical vapor deposition method.

    Science.gov (United States)

    Zhou, Ming; Feng, Chengheng; Wu, Chunxia; Ma, Weiwei; Cai, Lan

    2009-07-01

    The ZnO nanostructures were synthesized on Si(100) substrates by chemical vapor deposition (CVD) method. Different Morphologies of ZnO nanostructures, such as nanoparticle film, micro-pillar and micro-nano multi-structure, were obtained with different conditions. The results of XRD and TEM showed the good quality of ZnO crystal growth. Selected area electron diffraction analysis indicates the individual nano-wire is single crystal. The wettability of ZnO was studied by contact angle admeasuring apparatus. We found that the wettability can be changed from hydrophobic to super-hydrophobic when the structure changed from smooth particle film to single micro-pillar, nano-wire and micro-nano multi-scale structure. Compared with the particle film with contact angle (CA) of 90.7 degrees, the CA of single scale microstructure and sparse micro-nano multi-scale structure is 130-140 degrees, 140-150 degrees respectively. But when the surface is dense micro-nano multi-scale structure such as nano-lawn, the CA can reach to 168.2 degrees . The results indicate that microstructure of surface is very important to the surface wettability. The wettability on the micro-nano multi-structure is better than single-scale structure, and that of dense micro-nano multi-structure is better than sparse multi-structure.

  5. Heteroepitaxial Growth of GaN Nanostructures via Metalorganic Vapor Phase Epitaxy on Sapphire and Silicon using Graphene as Buffer Layer

    OpenAIRE

    Heilmann, Martin

    2017-01-01

    Modern high efficient optoelectronic devices, such as blue light emitting diodes or laser diodes in Blu-ray player, are based on the compound semiconductor GaN. Through its additional field of application as high frequency and high power transistors GaN could in the future even outshine Si as the most important semiconducting material. The lack of large area and cost-effective GaN substrates makes a growth of the aforementioned device structures on non-native substrates (e.g. sapphire) necess...

  6. Single crystal growth and electronic structure of TlPbI{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Khyzhun, O.Y., E-mail: khyzhun@ipms.kiev.ua [Frantsevych Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3 Krzhyzhanivsky Street, 03142 Kyiv (Ukraine); Fochuk, P.M. [Yuriy Fedkovich Chernivtsi National University, 2 Kotsyubynskogo Street, 58012 Chernivtsi (Ukraine); Kityk, I.V. [Faculty of Electrical Engineering, Czestochowa University of Technology, Armii Krajowej 17, PL-42-217 Czestochowa (Poland); Piasecki, M. [Institute of Physics, J.Dlugosz University Częstochowa, Armii Krajowej 13/15, Częstochowa (Poland); Levkovets, S.I. [Department of Inorganic and Physical Chemistry, Eastern European National University, 13 Voli Avenue, 43025 Lutsk (Ukraine); Fedorchuk, A.O. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska Street, 79010 Lviv (Ukraine); Parasyuk, O.V. [Department of Inorganic and Physical Chemistry, Eastern European National University, 13 Voli Avenue, 43025 Lutsk (Ukraine)

    2016-04-01

    High-quality inclusion-free TlPbI{sub 3} single crystals have been grown using Bridgman–Stockbarger method. The electronic structure of TlPbI{sub 3} is studied by using the possibilities of X-ray photoelectron spectroscopy (XPS). For the TlPbI{sub 3} crystal, XPS core-level and valence-band spectra for both pristine and Ar{sup +} ion-bombarded surfaces are recorded. The present XPS data indicate that the TlPbI{sub 3} single crystal surface is somewhat sensitive with respect to Ar{sup +} ion-bombardment. In particular, the XPS measurements reveal that thallium and lead atoms are in the formal valence +1 and +2, respectively, on the pristine TlPbI{sub 3} single crystal surface. Further, the 3.0 keV Ar{sup +} ion-bombardment of the surface induces partial transformation of lead ions to lower valence state, namely Pb{sup 0}; however, no partial loss of iodine atoms belonging to TlI{sub 8} polyhedra occurs due to the Ar{sup +} ion-bombardment of the TlPbI{sub 3} surface because after such a treatment thallium remains exclusively in the formal valence +1. The present XPS results indicate that low hygroscopicity is characteristic of the TlPbI{sub 3} single crystal surface. Photoinduced birefringence profiles in TlPbI{sub 3} are explored. - Highlights: • High-quality TlPbI{sub 3} single crystals have been grown by Bridgman–Stockbarger method. • Electronic structure of TlPbI{sub 3} is studied by the XPS method. • XPS data reveal low hygroscopicity of TlPbI{sub 3} surface. • TlPbI{sub 3} single crystal surface is sensitive with respect to Ar{sup +} ion-bombardment. • Photoinduced birefringence profiles in TlPbI{sub 3} are explored.

  7. Growth of large size lithium niobate single crystals of high quality by tilting-mirror-type floating zone method

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Abdur Razzaque, E-mail: razzaque_ru2000@yahoo.com [Department of Physics, University of Rajshahi (Bangladesh)

    2016-05-15

    Large size high quality LiNbO{sub 3} single crystals were grown successfully by tilting-mirror-type floating zone (TMFZ) technique. The grown crystals were characterized by X-ray diffraction, etch pits density measurement, Impedance analysis, Vibrating sample magnetometry (VSM) and UV-Visible spectrometry. The effect of mirror tilting during growth on the structural, electrical, optical properties and defect density of the LiNbO{sub 3} crystals were investigated. It was found that the defect density in the crystals reduced for tilting the mirror in the TMFZ method. The chemical analysis revealed that the grown crystals were of high quality with uniform composition. The single crystals grown by TMFZ method contains no low-angle grain boundaries, indicating that they can be used for high efficiency optoelectronic devices. (author)

  8. Nanostructured electronic and magnetic materials

    Indian Academy of Sciences (India)

    Research and development in nanostructured materials is one of the most intensely studied areas in science. As a result of concerted R & D efforts, nanostructured electronic and magnetic materials have achieved commercial success. Specific examples of novel industrially important nanostructured electronic and magnetic ...

  9. Controlled growth and electrical characterization of bent single-walled carbon nanotubes

    Science.gov (United States)

    Huang, Jun; Choi, Won Bong

    2008-12-01

    The frequency of appearance and curvature of zigzag shaped single-walled carbon nanotubes (SWNTs) are tailored by adjusting the gas flow rate, and changing the gas flow direction with respect to the step-edges on a single-crystal quartz substrate. The electrical resistance of SWNTs is found to increase with the number of bends. The resistance in SWNT segments with sharp curvature is observed to be 10-880 kΩ µm-1 higher than that in segments with smooth curvature. The increment in resistance may be attributed to the introduction of topological defects and heterojunctions at the curved part. Our results suggest the possibility of growing SWNTs with multiple-bend geometry in a simple one-step process and modulating the conductance of SWNTs by controlling the number of bends and the curvature of bends.

  10. Growth and characterization of organometallic L-alanine cadmium chloride single crystal by slow evaporation technique

    International Nuclear Information System (INIS)

    Bright, K.C.; Freeda, T.H.

    2010-01-01

    Single crystals of L-alanine cadmium chloride (LACC), an organometallic nonlinear optical material, have been grown by the slow evaporation technique. The grown crystals were subjected to various characterization techniques, such as single crystal and powder XRD, FTIR, UV-vis and TGA-DTA. The mechanical properties of the crystals show that this material belongs to the category of hard materials. Second harmonic generation was confirmed by the Kurtz and Perry powder technique. Electrical parameters, such as dielectric constant, dielectric loss, ac and dc conductivity and their corresponding activation energies have been studied. The low dielectric constant and dielectric loss suggest that this material is a good candidate for micro-electronic applications.

  11. Growth of niobium single crystals by pulling from a melt on a pedestal. II

    International Nuclear Information System (INIS)

    Naramoto, H.; Kamada, K.

    1975-01-01

    The following improvements were made in growing niobium single crystals by pulling from a melt in a pedestal heated by electron beam bombardment: (1) use of single crystalline seed; (2) rotation of the seed crystal as well as the pedestal; and (3) reduction of the pulling rate down to about 0.15 mm/min. The perfection of these crystals were assessed by taking both projection and section topographs under both the thick crystal case and thin crystal case. In the former case, diffusion of defect-images, which might overlook the grown-in dislocations, was critically examined. As a result of these measurements it was established that the niobium crystals are free from any grown-in dislocations. No propagation of dislocations from the seed to the grown crystal was observed. (Auth.)

  12. Thermographic analyses of the growth of Cd1-xZnxTe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kopach, O.V.; Bolotnikov, A.; Shcherbak, Larysa P.; Fochuk, Petro M.; and James, Ralph B.

    2010-08-01

    Bulk Cd1-xZnxTe (0single crystals for gamma-ray detectors are grown mainly from near-stoichiometric melts. We discuss the influence of the thermal pre-history of the melts (superheating, thermo-cycling, and cooling rate) on various physical properties based on our thermographic analyses, electrical conductivity and viscosity measurements. Increasing the Zn content causes non-monotonic dependencies in the quality of the crystals structure.

  13. Effect of zinc acetate addition on crystal growth, structural, optical, thermal properties of glycine single crystals

    Directory of Open Access Journals (Sweden)

    S. Anbu Chudar Azhagan

    2017-05-01

    Full Text Available In the present study, γ-glycine has been crystallized by using zinc acetate dihydrate as an additive for the first time by slow solvent evaporation method. The second harmonic conversion efficiency of γ-glycine crystal was determined using Kurtz and Perry powder technique and was found to be 3.66 times greater than that of standard inorganic material potassium dihydrogen phosphate (KDP. The analytical grade chemicals of glycine and zinc acetate dihydrate were taken in six different molar ratios: 1:0.2, 1:0.4, 1:0.6, 1:0.7, 1:0.8, and 1:0.9 respectively to find out the γ-polymorph of glycine. The lower molar concentration of zinc acetate yield only α-polymorph where as the higher molar concentration of zinc acetate inhibits the γ-polymorph of glycine which was confirmed by single crystal XRD and powder XRD studies. Inductively coupled plasma optical emission spectrometry (ICP-OES was carried out to quantify the concentration of zinc element in the grown glycine single crystals. The concentration of zinc element in the presence of grown γ-glycine single crystal is found to be 0.73 ppm. UV–Visible–NIR transmittance spectra were recorded for the samples to analyse the transparency in visible and near infrared region (NIR. The optical band gap Eg was estimated for γ-glycine single crystal using UV–Visible–NIR study. Functional groups present in the samples were identified by FTIR spectroscopic analysis. Differential scanning calorimetry technique was employed to determine the phase transition, thermal stability and melting point of the grown crystal.

  14. Growth and characterisation of single crystals of ternary chalcogenides for laser applications

    NARCIS (Netherlands)

    Isaenko, L.; Yelisseyev, A.; Zondy, J. J.; Knippels, G.; Thenot, I.; Lobanov, S.

    2001-01-01

    Bulk single crystals up to 20 mm in diameter and 40 mm long for LiInS2 and up to 10 mm, 20 mm, respectively, for LiInSe2 have been grown. Their colour changed from colourless to rose for the first one and from yellow to dark red for the other All crystals have wurtzite-type lattice (Pna2(1) space

  15. Single Crystal Growth and Magnetic Properties of Ferromagnetic URhGe2

    International Nuclear Information System (INIS)

    Matsuda, T.D.; Haga, Y.; Tokiwa, Y.; Galatanu, A.; Yamamoto, E.; Okubo, T.; Onuki, Y.

    2003-01-01

    We have successfully grown a single crystal of uranium intermetallic compound URhGe 2 . The temperature dependence of electrical resistivity shows highly anisotropic behavior. Two anomalies, which correspond to the magnetic ordering temperatures, were observed in the resistivity, magnetic susceptibility and specific heat measurements at T M1 30 K and T M2 =25 K. The magnetic susceptibility also shows a large uniaxial anisotropy with a magnetic easy-axis along the [010] direction. (author)

  16. single crystal growth, x-ray structure analysis, optical band gap

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... Hg...Hgand Cl...Cl interactions are stabilizing the structures in 3D pattern. UV-vis absorption spectra illustrate the change in opticalband gap from 3.01eVto 3.42eV on replacing the metal halide group.Raman and Hyper-Raman tensors calculations were performed based on single crystal X-ray data and the ...

  17. Growth of ultra radiation hard NaBi(WO4)2 single crystal

    International Nuclear Information System (INIS)

    Govind Singh, S.; Tyagi, Mohit; Singh, Awadh K.; Sangeeta

    2009-01-01

    Single crystals of undoped NaBi(WO 4 ) 2 were grown under different condition by Czochralski technique. Radiation hardness of the crystals was studied by irradiating them up to 10''5 and 10''6 Gy dose at a fast rate (2 Gy/sec) using 60 Co as a gamma source. Transmission spectra of the crystal samples were recorded and analyzed. It is found that crystal grown from recrystalized charge shows very good optical quality and excellent radiation hardness. (author)

  18. Growth and characterization of 4-chloro-3-nitrobenzophenone single crystals using vertical Bridgman technique

    Energy Technology Data Exchange (ETDEWEB)

    Aravinth, K., E-mail: anandcgc@gmail.com; Babu, G. Anandha, E-mail: anandcgc@gmail.com; Ramasamy, P., E-mail: anandcgc@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam -603110, Tamilnadu (India)

    2014-04-24

    4-chloro-3-nitrobenzophenone (4C3N) has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The micro hardness measurements were used to analyze the mechanical property of the grown crystal.

  19. On the compliant behaviour of free-standing Si nanostructures on Si(001) for Ge nanoheteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, Grzegorz

    2012-04-24

    Selective chemical vapor deposition Ge heteroepitaxy approaches for high quality Ge nanostructure growth with reasonable thermal budget must be developed for local Ge photonic module integration. A promising vision is offered by the compliant substrate effects within nanometer scale Ge/Si heteroepitaxial structures. Here, in contrast to the classical Ge deposition on bulk Si substrates, the thermal and lattice mismatch strain energy accumulated in the Ge epilayer is partially shifted to the free-standing Si nanostructure. This strain partitioning phenomenon is at the very heart of the nanoheteroepitaxy theory (NHE) and, if strain energy levels are correctly balanced, offers the vision to grow defect-free nanostructures of lattice mismatched semiconductors on Si. In case of the Ge/Si heterosystem with a lattice mismatch of 4.2%, the strain partitioning phenomenon is expected to be triggered when free-standing Si nanopillars with the width of 50 nm and below are used. In order to experimentally verify NHE with its compliant substrate effects, a set of free-standing Ge/Si nanostructures with diameter ranging from 150 to 50 nm were fabricated and investigated. The main limitation corresponds to a simultaneous detection of (a) the strain partitioning phenomenon between Ge and Si and (b) the absence of defects on the nano-scale. In this respect, synchrotron-based grazing incidence X-ray diffraction was applied to study the epitaxial relationship, defect and strain characteristics with high resolution and sensitivity in a non-destructive way. Raman spectroscopy supported by finite element method calculations were used to investigate the strain distribution within a single Ge/Si nanostructure. Special focus was devoted to transmission electron microscopy to determine the quality of the Ge epilayer. It was found, that although high quality Ge nanoclusters can be achieved by thermal annealing on Si pillars bigger than 50 nm in width, no proof of strain partitioning

  20. Growth and characterization of Sm3+ doped cerium oxalate single crystals

    Directory of Open Access Journals (Sweden)

    Minu Mary C

    2016-07-01

    Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

  1. Chiral Inorganic Nanostructures.

    Science.gov (United States)

    Ma, Wei; Xu, Liguang; de Moura, André F; Wu, Xiaoling; Kuang, Hua; Xu, Chuanlai; Kotov, Nicholas A

    2017-06-28

    The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of individual nanoparticles (NPs) and their assemblies and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others. Multiple chiral geometries were observed with characteristic scales from ångströms to microns. Uniquely high values of chiral anisotropy factors that spurred the development of the field and differentiate it from chiral structures studied before, are now well understood; they originate from strong resonances of incident electromagnetic waves with plasmonic and excitonic states typical for metals and semiconductors. At the same time, distinct similarities with chiral supramolecular and biological systems also emerged. They can be seen in the synthesis and separation methods, chemical properties of individual NPs, geometries of the nanoparticle assemblies, and interactions with biological membranes. Their analysis can help us understand in greater depth the role of chiral asymmetry in nature inclusive of both earth and space. Consideration of both differences and similarities between chiral inorganic, organic, and biological nanostructures will also accelerate the development of technologies based on chiroplasmonic and chiroexcitonic effects. This review will cover both experiment and theory of chiral nanostructures starting with the origin and multiple components of mirror asymmetry of individual NPs and their assemblies. We shall consider four different types of chirality in nanostructures and related physical, chemical, and

  2. Monitoring the formation of inorganic fullerene-like MoS{sub 2} nanostructures by laser ablation in liquid environments

    Energy Technology Data Exchange (ETDEWEB)

    Compagnini, Giuseppe, E-mail: gcompagnini@unict.it [Dipartimento di Scienze Chimiche, Universita di Catania, Viale A.Doria 6, 95125, Catania (Italy); Sinatra, Marco G.; Messina, Gabriele C.; Patane, Giacomo [Dipartimento di Scienze Chimiche, Universita di Catania, Viale A.Doria 6, 95125, Catania (Italy); Scalese, Silvia [Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, Zona industriale VIII, Strada n.5, 95121, Catania (Italy); Puglisi, Orazio [Dipartimento di Scienze Chimiche, Universita di Catania, Viale A.Doria 6, 95125, Catania (Italy)

    2012-05-15

    Laser ablation of solid targets in liquid media is emerging as a simple, clean and reproducible way to generate a large number of intriguing nanometric structures with peculiar properties. In this work we present some results on the formation of MoS{sub 2} fullerene-like nanoparticles (10-15 nm diameter) obtained by the ablation of crystalline targets in water. Such a top-down approach can be considered greener than standard sulphidization reactions and represents an intriguing single step procedure. The generation of the MoS{sub 2} nanostructures is in competition with that of oxide clusters and strongly depends on the oxidative environment created by the plasma plume. The size, shape and crystalline phase of the obtained nanoparticles are studied by microscopy while X-Ray Photoelectron Spectroscopy is used to investigate the chemical state of produced nanostructures and to propose mechanisms for their growth.

  3. Nanostructured piezoelectric energy harvesters

    CERN Document Server

    Briscoe, Joe

    2014-01-01

    This book covers a range of devices that use piezoelectricity to convert mechanical deformation into electrical energy and relates their output capabilities to a range of potential applications. Starting with a description of the fundamental principles and properties of piezo- and ferroelectric materials, where applications of bulk materials are well established, the book shows how nanostructures of these materials are being developed for energy harvesting applications. The authors show how a nanostructured device can be produced, and put in context some of the approaches that are being invest

  4. Direct atomic force microscopy observation of DNA tile crystal growth at the single-molecule level.

    Science.gov (United States)

    Evans, Constantine G; Hariadi, Rizal F; Winfree, Erik

    2012-06-27

    While the theoretical implications of models of DNA tile self-assembly have been extensively researched and such models have been used to design DNA tile systems for use in experiments, there has been little research testing the fundamental assumptions of those models. In this paper, we use direct observation of individual tile attachments and detachments of two DNA tile systems on a mica surface imaged with an atomic force microscope (AFM) to compile statistics of tile attachments and detachments. We show that these statistics fit the widely used kinetic Tile Assembly Model and demonstrate AFM movies as a viable technique for directly investigating DNA tile systems during growth rather than after assembly.

  5. Steady-state crack growth in single crystals under Mode I loading

    DEFF Research Database (Denmark)

    Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2017-01-01

    at the crack tip predicted by Rice [Rice J.R., 1987. Tensile crack tip fields in elastic-ideally plastic crystals. Mech. Mater. 6, pp. 317–335] for quasi-static crack growth are confirmed through the numerical simulations and highly refined details are revealed. Through a detailed study, it is demonstrated...... monotonically increases the crack tip shielding, whereas the opposite behaviour is observed at high velocities. This observation leads to the existence of a characteristic velocity at which the crack tip shielding becomes independent of the rate-sensitivity....

  6. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  7. Czochralski growth and scintillation properties of Ce: (Gd, Y,Lu) .sub.3./sub. (Al,Ga).sub.5./sub.O.sub.12./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Kamada, K.; Průša, Petr; Nikl, Martin; Blažek, K.; Endo, T.; Tsutsumi, K.; Kurosawa, S.; Yokota, Y.; Yoshikawa, A.

    2014-01-01

    Roč. 61, č. 1 (2014), 293-296 ISSN 0018-9499 Institutional support: RVO:68378271 Keywords : oxides * scintillator materials * scintillators * single crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2014

  8. Thin metal nanostructures: synthesis, properties and applications

    OpenAIRE

    Fan, Zhanxi; Huang, Xiao; Tan, Chaoliang; Zhang, Hua

    2014-01-01

    Two-dimensional nanomaterials, especially graphene and single- or few-layer transition metal dichalcogenide nanosheets, have attracted great research interest in recent years due to their distinctive physical, chemical and electronic properties as well as their great potentials for a broad range of applications. Recently, great efforts have also been devoted to the controlled synthesis of thin nanostructures of metals, one of the most studied traditional materials, for various applications. I...

  9. Binary DNA Nanostructures for Data Encryption

    OpenAIRE

    Halvorsen, Ken; Wong, Wesley P.

    2012-01-01

    We present a simple and secure system for encrypting and decrypting information using DNA self-assembly. Binary data is encoded in the geometry of DNA nanostructures with two distinct conformations. Removing or leaving out a single component reduces these structures to an encrypted solution of ssDNA, whereas adding back this missing "decryption key" causes the spontaneous formation of the message through self-assembly, enabling rapid read out via gel electrophoresis. Applications include auth...

  10. Binary DNA nanostructures for data encryption.

    Science.gov (United States)

    Halvorsen, Ken; Wong, Wesley P

    2012-01-01

    We present a simple and secure system for encrypting and decrypting information using DNA self-assembly. Binary data is encoded in the geometry of DNA nanostructures with two distinct conformations. Removing or leaving out a single component reduces these structures to an encrypted solution of ssDNA, whereas adding back this missing "decryption key" causes the spontaneous formation of the message through self-assembly, enabling rapid read out via gel electrophoresis. Applications include authentication, secure messaging, and barcoding.

  11. Preparation of 1D nanostructures using biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Pruneanu, Stela; Olenic, Liliana; Kacso, Irina [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Tudoran, Lucian Barbu [Babes-Bolyai University, Electron Microscopy Center, 1 Mihail Kogalniceanu, 400006 Cluj-Napoca (Romania); Al-Said, Said A Farha; Hassanien, Reda; Houlton, Andrew; Horrocks, Benjamin R, E-mail: stela.pruneanu@itim-cj.r [School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom)

    2009-08-01

    In this paper we have shown that one-dimensional (1D) particle arrays can be obtained using biomolecules, like DNA or amino-acids. Nano-arrays of silver and gold were prepared in a single-step synthesis, by exploiting the binding abilities of {lambda}-DNA and L-Arginine. The morphology and optical properties of these nanostructures were investigated using AFM, TEM and UV-Vis absorption spectroscopy.

  12. Modeling of dopant segregation in sapphire single crystal fibre growth by Micro-Pulling-Down method

    Science.gov (United States)

    Wenjia, Su; Duffar, Thierry; Nehari, Abdeljelil; Kononets, Valerii; Lebbou, Kheirreddine

    2017-09-01

    Experiments and numerical simulations are conducted in order to study the causes and solutions for the Ti inhomogeneity problem in Ti doped sapphire Micro-Pulling-Down (μ-PD) growth. The measurement and modeling of the thermal and flow fields, electromagnetic field, Ti concentration in the molten zone and along the fibre axis are compared. For the mean Ti concentration along the fibre and temperature along the iridium crucible, the modeling results are consistent with experiments. Results showed that for high pulling rate, the mass transfer in the capillary is dominated by convection. Marangoni convection is strong in the meniscus due to the large temperature gradient, which has great impact on the Ti distribution for different fibre radii. For high pulling rate, Ti concentration increases quickly from the seed along the fibre axis, and reaches a constant value after about 0.5-2 mm. Radial segregation is high for large diameter fibres. The constant Ti concentration along the fibre axis is increasing when increasing the fibre radius from 0.2 to 0.6 mm. For 0.8 mm, it decreases due to the change of the vortex. At low growth rate, the transport in the capillary is diffusive, back to the crucible, which leads to a Scheil-like Ti distribution, in full agreement with the experimental results.

  13. Steady-State Crack Growth in Rate-Sensitive Single Crystals

    DEFF Research Database (Denmark)

    Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2016-01-01

    The characteristics of the active plastic zone surrounding a crack growingin a single crystal (FCC, BCC, and HCP) at constant velocity is investigated for ModeI loading under plane strain assumptions. The framework builds upon a steady-state relation bringing the desired solution out in a frame...... translating with the crack tip. In the study, the shielding of the crack tip that follows from plastic slip is investigated by adopting the SSV-model. High resolution plots of the plastic zones are obtained and a detailed study confirms the existence of analytically determined velocity discontinuities from...

  14. Growth of single-wall carbon nanotubes by chemical vapor deposition for electrical devices

    OpenAIRE

    Furer, Jürg

    2006-01-01

    Carbon emerges in di®erent forms. Diamond and graphite have been well known mate- rials for centuries. Moreover fullerenes and nanotubes were discovered only a few years ago. H. W. Kroto et al. depicted the fullerenes in 1985 [1]. A few years later, in 1991, S. Iijima described carbon nanotubes (CNTs) for the ¯rst time [2] (Figure 1.1). CNTs have a close relation to graphite, since a single-wall carbon nanotube is like a rolled-up graphite mono layer. However a nanotube has wi...

  15. Stress induced growth of Sn nanowires in a single step by sputtering method

    Science.gov (United States)

    Yadav, A.; Patel, N.; Miotello, A.; Kothari, D. C.

    2015-06-01

    Sn nanowires in aluminum film have been synthesized in a single step by co-sputtering of Al and Sn targets. Due to immiscibility of Sn and Al, co-sputtering leads to generation of stress in the composite film. In order to attain thermodynamic equilibrium, Sn separates from Al and diffuses towards the grain boundaries. External perturbation due to ambient atmosphere leads to corrosion at the grain boundaries forming pits which provide path for Sn to evolve. Owing to this, extrusion of Sn nanowires from Al film occurs to release the residual stress in the film.

  16. Single crystal growth and physical properties in UPd 2(Al 1- xGa x) 3

    Science.gov (United States)

    Aso, Naofumi; Sato, Noriaki; Komatsubara, Takemi

    1999-01-01

    Measurements of specific heat, electrical resistivity and magnetization for single crystalline samples of UPd 2(Al 1- xGa x) 3 for Ga concentrations of x⩽0.2 are presented for the first time. As the gallium atom is substituted for the aluminum, the superconducting transition temperature Tc indicates a rapid decrease and the antiferromagnetic transition temperature TN reduces gradually. We found an entropy released at TN to decrease with the increase of x, suggesting that the increase of spin fluctuations is responsible for the reduction of TN. We also discuss the x-dependence of the magnetic susceptibility.

  17. Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

    Science.gov (United States)

    Karthigha, S.; Krishnamoorthi, C.

    2018-03-01

    An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

  18. Epitaxial growth of fcc-CoxNi100-x thin films on MgO(110) single-crystal substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Nukaga, Yuri; Sato, Yoichi; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-01-01

    Co x Ni 100-x (x=100, 80, 20, 0 at. %) epitaxial thin films were prepared on MgO(110) single-crystal substrates heated at 300 deg. C by ultrahigh vacuum molecular beam epitaxy. The growth mechanism is discussed based on lattice strain and crystallographic defects. CoNi(110) single-crystal films with a fcc structure are obtained for all compositions. Co x Ni 100-x film growth follows the Volmer-Weber mode. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of the Co x Ni 100-x films are in agreement within ±0.5% with the values of the respective bulk Co x Ni 100-x crystals, suggesting that the strain in the film is very small. High-resolution cross-sectional transmission microscopy shows that an atomically sharp boundary is formed between a Co(110) fcc film and a MgO(110) substrate, where periodical misfit dislocations are preferentially introduced in the film at the Co/MgO interface. The presence of such periodical misfit dislocations relieves the strain caused by the lattice mismatch between the film and the substrate.

  19. Graphene directed architecture of fine engineered nanostructures with electrochemical applications

    DEFF Research Database (Denmark)

    Hou, Chengyi; Zhang, Minwei; Halder, Arnab

    2017-01-01

    . In this review, we aim to highlight some recent efforts devoted to rational design, assembly and fine engineering of electrochemically active nanostructures using graphene or/and its derivatives as soft templates for controlled synthesis and directed growth. We organize the contents according to the chemically...... classified nanostructures, including metallic nanostructures, self-assembled organic and supramolecular structures, and fine engineered metal oxides. In these cases, graphene templates either sacrificed during templating synthesis or retained as support for final products. We also discuss remained challenges...... and future perspective in the graphene-templating design and synthesis of various materials. Overall, this review could offer crucial insights into the nanoscale engineering of new nanostructures using graphene as a soft template and their potential applications in electrochemical science and technology. We...

  20. Single-domain antibodies that compete with the natural ligand fibroblast growth factor block the internalization of the fibroblast growth factor receptor 1

    International Nuclear Information System (INIS)

    Highlights: → Recombinant antibodies for FGFR1 were isolated from a llama naive library in VHH format. → These antibodies compete with the natural ligand FGF-2 for the same epitope on FGFR1. → The antibody competition inhibits the FGF-2-dependent internalization of FGFR1. -- Abstract: Single-domain antibodies in VHH format specific for fibroblast growth factor receptor 1 (FGFR1) were isolated from a phage-display llama naive library. In particular, phage elution in the presence of the natural receptor ligand fibroblast growth factor (FGF) allowed for the identification of recombinant antibodies that compete with FGF for the same region on the receptor surface. These antibodies posses a relatively low affinity for FGFR1 and were never identified when unspecific elution conditions favoring highly affine binders were applied to panning procedures. Two populations of competitive antibodies were identified that labeled specifically the receptor-expressing cells in immunofluorescence and recognize distinct epitopes. Antibodies from both populations effectively prevented FGF-dependent internalization and nuclear accumulation of the receptor in cultured cells. This achievement indicates that these antibodies have a capacity to modulate the receptor physiology and, therefore, constitute powerful reagents for basic research and a potential lead for therapeutic applications.