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Sample records for bioconjugated inp quantum

  1. Imaging Pancreatic Cancer Using Bioconjugated InP Quantum Dots

    OpenAIRE

    Yong, Ken-Tye; Ding, Hong; Roy, Indrajit; Law, Wing-Cheung; Bergey, Earl J.; Maitra, Anirban; Prasad, Paras N.

    2009-01-01

    In this paper, we report the successful use of non-cadmium based quantum dots (QDs) as highly efficient and non-toxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulphide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in non-aqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjug...

  2. Spectroscopic behavior of bioconjugated quantum dots

    Science.gov (United States)

    Chornokur, G.; Ostapenko, S.; Emirov, Yu; Korsunska, N. E.; Sellers, T.; Phelan, C.

    2008-07-01

    We report on a short-wavelength, 'blue' spectral shift of the photoluminescence (PL) spectrum in CdSeTe/ZnS core/shell quantum dots (QDs) caused by bioconjugation with several monoclonal cancer-related antibodies (ABs). Scanning PL spectroscopy was performed on samples dried on solid substrates at various temperatures. The influence of the AB chemical origin on the PL spectral shift was observed. The QD-AB conjugation reaction was confirmed using the agarose gel electrophoresis technique. The spectral shift was strongly increased and the process facilitated when the samples were dried above room temperature. The PL spectroscopic mapping revealed a profile of the PL spectral shift across the dried QD-AB spot. A mechanism of the blue shift is attributed to changes in the QD electronic energy levels caused by a local stress applied to the bioconjugated QD.

  3. Fluorescence plate reader for quantum dot-protein bioconjugation analysis.

    Science.gov (United States)

    Carvalho, Kilmara H G; Brasil, Aluizio G; Cabral Filho, Paulo E; Tenório, Denise P L A; de Siqueira, Ana C A; Leite, Elisa S; Fontes, Adriana; Santos, Beate S

    2014-05-01

    We present here a new and alternative method that uses a Fluorescence Plate Reader in a different approach, not to study protein-protein interactions, but to evaluate the efficiency of the protein bioconjugation to quantum dots (QDs). The method is based on the QDs' native fluorescence and was successfully tested by employing two different QDs-proteins conjugation methodologies, one by promoting covalent binding and other by inducing adsorption processes. For testing, we used bioconjugates between carboxyl coated CdTe QDs and bovine serum albumin, concanavalin A lectin and anti-A antibody. Flow cytometry and fluorescence spectroscopy studies corroborated the results found by the Fluorescence Plate Reader assay. This kind of analysis is important because poor bioconjugation efficiency leads to unsuccessful applications of the fluorescent bioconjugates. We believe that our method presents the possibility of performing semi-quantitative and simultaneous analysis of different samples with accuracy taking the advantage of the high sensitivity of optical based measurements. PMID:24734547

  4. Bioconjugated silicon quantum dots from one-step green synthesis

    Science.gov (United States)

    Intartaglia, Romuald; Barchanski, Annette; Bagga, Komal; Genovese, Alessandro; Das, Gobind; Wagener, Philipp; di Fabrizio, Enzo; Diaspro, Alberto; Brandi, Fernando; Barcikowski, Stephan

    2012-02-01

    Biofunctionalized silicon quantum dots were prepared through a one step strategy avoiding the use of chemical precursors. UV-Vis spectroscopy, Raman spectroscopy and HAADF-STEM prove oligonucleotide conjugation to the surface of silicon nanoparticle with an average size of 4 nm. The nanoparticle size results from the size-quenching effect during in situ conjugation. Photoemissive properties, conjugation efficiency and stability of these pure colloids were studied and demonstrate the bio-application potential, e.g. for nucleic acid vector delivery with semiconducting, biocompatible nanoparticles.Biofunctionalized silicon quantum dots were prepared through a one step strategy avoiding the use of chemical precursors. UV-Vis spectroscopy, Raman spectroscopy and HAADF-STEM prove oligonucleotide conjugation to the surface of silicon nanoparticle with an average size of 4 nm. The nanoparticle size results from the size-quenching effect during in situ conjugation. Photoemissive properties, conjugation efficiency and stability of these pure colloids were studied and demonstrate the bio-application potential, e.g. for nucleic acid vector delivery with semiconducting, biocompatible nanoparticles. Electronic supplementary information (ESI) available: Experimental details of sample preparation, sample characterizations. Additional results of UV-vis, HAADF-STEM, Raman spectroscopy of bioconjugated silicon dots and ICP-OES of deionized water used for the synthesis are presented in Fig. S1, S3, S2, and S4 and Table S2, respectively. See DOI: 10.1039/c2nr11763k

  5. Multiphoton imaging of quantum dot bioconjugates in cultured cells following Nd:YLF laser excitation

    Science.gov (United States)

    Serrano, Elba E.; Knight, V. B.

    2005-04-01

    Quantum dot bioconjugates offer unprecedented opportunities for monitoring biological processes and molecular interactions in cells, tissues, and organs. We are interested in developing applications that permit investigation of physiological processes and cytoskeletal organization in live cells, and allow imaging of complex organs, such as the auditory and vestibular sensory structures of the inner ear. Multiphoton microscopy is a powerful technique for acquiring images from deep within a sample while reducing phototoxic effects of laser light exposure on cells. Previous studies have established that a solid-state Nd:YLF laser can be used to acquire two-photon and three-photon images from live cells while minimizing phototoxic side effects (Wokosin et al., 1996, Bioimaging, 4:208-214; Squirrell et al., 1999, Nature Biotechnology, 8:763-767). We present here the results of experiments using an all-solid-state Nd:YLF 1047 nm femtosecond laser (Microlase DPM1000) source to excite quantum dot bioconjugates. Cells were labeled with Qdot (Quantum Dot Corporation) bioconjugates or with Alexa Fluor (Molecular Probes) bioconjugates and then imaged with a BioRad 1024 confocal microscope configured for multiphoton imaging using internal or external (non-descanned) detectors. Results demonstrate that the Nd:YLF laser can be used to stimulate fluorescence emission of quantum dots and Alexa Fluor bioconjugates in cultured amphibian (Xenopus) and mammalian (rat, chinese hamster) cells. We conclude that the Nd:YLF laser is a viable excitation source that extends the applicability of quantum dots for investigation of biological processes using multiphoton microscopy.

  6. The influence of bio-conjugation on photoluminescence of CdSe/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Torchynska, Tetyana V. [ESFM Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional, México, D.F. 07738 (Mexico); Vorobiev, Yuri V. [Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV) Querétaro, Libramiento Norponiente 2000, Fracc. Real de Juriquilla, 76230 Querétaro (Mexico); Makhniy, Victor P. [Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky Str., 58012 Chernivtsi (Ukraine); Horley, Paul P., E-mail: paul.horley@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Chihuahua/Monterrey, 120 Avenida Miguel de Cervantes, 31109 Chihuahua (Mexico)

    2014-11-15

    We report a considerable blue shift in the luminescence spectra of CdSe/ZnS quantum dots conjugated to anti-interleukin-10 antibodies. This phenomenon can be explained theoretically by accounting for bio-conjugation as a process causing electrostatic interaction between a quantum dot and an antibody, which reduces effective volume of the dot core. To solve the Schrödinger equation for an exciton confined in the quantum dot, we use mirror boundary conditions that were successfully tested for different geometries of quantum wells.

  7. The influence of bio-conjugation on photoluminescence of CdSe/ZnS quantum dots

    International Nuclear Information System (INIS)

    We report a considerable blue shift in the luminescence spectra of CdSe/ZnS quantum dots conjugated to anti-interleukin-10 antibodies. This phenomenon can be explained theoretically by accounting for bio-conjugation as a process causing electrostatic interaction between a quantum dot and an antibody, which reduces effective volume of the dot core. To solve the Schrödinger equation for an exciton confined in the quantum dot, we use mirror boundary conditions that were successfully tested for different geometries of quantum wells

  8. Band Structure Modifications in Deformed InP Quantum Wires

    Directory of Open Access Journals (Sweden)

    V.V. Kuryliuk

    2014-11-01

    Full Text Available The work describes the features of the band structure of deformed InP nanowires with different diameters. It is shown that the bending of quantum wires is capable of creating local minima in the conduction and valence bands which are separated from the surface of the cylindrical wire. This result opens up new possibilities for controlling both the lifetime of photoexcited carriers by keeping them at these minima and the magnitude of the photovoltage in solar energy conversion devices based on quantum wires. The work lies within a common goal aiming to develop new methods of functionalization of nanostructured surfaces using mechanical deformations.

  9. Quantum beats in photoluminescence of InP quantum dots in electric field

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, V.; Ren, H.W.; Sugisaki, M. [ERATO, JST, Tsukuba (Japan). Single Quantum Dot Project; Fedorov, A.V. [Vavilov State Optical Inst., St. Petersburg (Russian Federation); Ignatiev, I.V.; Kozin, I.E. [ERATO, JST, Tsukuba (Japan). Single Quantum Dot Project; Sankt-Peterburgskij Univ. (Russian Federation). Research Inst. of Physics; Sugou, S. [ERATO, JST, Tsukuba (Japan). Single Quantum Dot Project; NEC Corp., Tsukuba (Japan). Opto-Electronics Research Labs.; Masumoto, Y. [ERATO, JST, Tsukuba (Japan). Single Quantum Dot Project; Tsukuba Univ., Sakura, Ibaraki (Japan). Inst. of Physics

    2001-03-08

    The photoluminescence (PL) kinetics of heterostructures with InP self-assembled quantum dots are studied under quasi-resonant pulse excitation in the presence of an external electric field. An oscillatory behavior of the PL kinetics is shown to arise due to quantum beats of the radiative states. A model of the coherent excitation of nonresonant PL is proposed. (orig.)

  10. Peculiarities of Raman scattering in bioconjugated CdSe/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Cano, A; Jimenez Sandoval, S; Vorobiev, Y; Rodriguez Melgarejo, F [CINVESTAV-IPN, Santiago de Queretaro, Queretaro 76230 (Mexico); Torchynska, T V [ESFM-Instituto Politecnico Nacional, Mexico DF 07738 (Mexico)

    2010-04-02

    The article presents the results of analysis of Raman scattering spectra of non-conjugated and bioconjugated CdSe/ZnS core-shell quantum dots (QDs). Commercial CdSe/ZnS QDs used covered by polymer are characterized by color emission with the maxima at 605-610 nm (2.03-2.05 eV). The bioconjugation process is performed to biomolecules-the antihuman Interleukin 10 (IL10) antibodies (mab). Raman scattering spectra measured at room temperature with excitation by a He-Ne laser line (632.8 nm) demonstrate two groups of peaks: (1) related to the Si substrate at 230-460, 522, 610, 670, 940-1040 cm{sup -1} and (2) to the PEG polymer on the QD surface in the range of 837-3320 cm{sup -1}. It is revealed that the CdSe/ZnS QD bioconjugation to the antihuman Interleukin 10 antibodies is accompanied with the dramatic changes in the intensity of the Raman lines of both types: the intensity of the Si related line increases six- or ten-fold, but the intensity of the polymer related line decreases ten-fold. The models explaining the mentioned effects in Raman scattering spectra have been discussed.

  11. Surface processes during purification of InP quantum dots

    Directory of Open Access Journals (Sweden)

    Natalia Mordvinova

    2014-08-01

    Full Text Available Recently, a new simple and fast method for the synthesis of InP quantum dots by using phosphine as phosphorous precursor and myristic acid as surface stabilizer was reported. Purification after synthesis is necessary to obtain samples with good optical properties. Two methods of purification were compared and the surface processes which occur during purification were studied. Traditional precipitation with acetone is accompanied by a small increase in photoluminescence. It occurs that during the purification the hydrolysis of the indium precursor takes place, which leads to a better surface passivation. The electrophoretic purification technique does not increase luminescence efficiency but yields very pure quantum dots in only a few minutes. Additionally, the formation of In(OH3 during the low temperature synthesis was explained. Purification of quantum dots is a very significant part of postsynthetical treatment that determines the properties of the material. But this subject is not sufficiently discussed in the literature. The paper is devoted to the processes that occur at the surface of quantum dots during purification. A new method of purification, electrophoresis, is investigated and described in particular.

  12. Multidentate Polymer Coatings for Compact and Homogeneous Quantum Dots with Efficient Bioconjugation.

    Science.gov (United States)

    Ma, Liang; Tu, Chunlai; Le, Phuong; Chitoor, Shweta; Lim, Sung Jun; Zahid, Mohammad U; Teng, Kai Wen; Ge, Pinghua; Selvin, Paul R; Smith, Andrew M

    2016-03-16

    Quantum dots are fluorescent nanoparticles used to detect and image proteins and nucleic acids. Compared with organic dyes and fluorescent proteins, these nanocrystals have enhanced brightness, photostability, and wavelength tunability, but their larger size limits their use. Recently, multidentate polymer coatings have yielded stable quantum dots with small hydrodynamic dimensions (≤10 nm) due to high-affinity, compact wrapping around the nanocrystal. However, this coating technology has not been widely adopted because the resulting particles are frequently heterogeneous and clustered, and conjugation to biological molecules is difficult to control. In this article we develop new polymeric ligands and optimize coating and bioconjugation methodologies for core/shell CdSe/CdxZn1-xS quantum dots to generate homogeneous and compact products. We demonstrate that "ligand stripping" to rapidly displace nonpolar ligands with hydroxide ions allows homogeneous assembly with multidentate polymers at high temperature. The resulting aqueous nanocrystals are 7-12 nm in hydrodynamic diameter, have quantum yields similar to those in organic solvents, and strongly resist nonspecific interactions due to short oligoethylene glycol surfaces. Compared with a host of other methods, this technique is superior for eliminating small aggregates identified through chromatographic and single-molecule analysis. We also demonstrate high-efficiency bioconjugation through azide-alkyne click chemistry and self-assembly with hexa-histidine-tagged proteins that eliminate the need for product purification. The conjugates retain specificity of the attached biomolecules and are exceptional probes for immunofluorescence and single-molecule dynamic imaging. These results are expected to enable broad utilization of compact, biofunctional quantum dots for studying crowded macromolecular environments such as the neuronal synapse and cellular cytoplasm. PMID:26863113

  13. Self-assembled quantum dot-bioconjugates: characterization and use for sensing proteolytic activity

    Science.gov (United States)

    Medintz, Igor L.; Pons, Thomas; Sapsford, Kim E.; Dawson, Philip E.; Mattoussi, Hedi

    2008-04-01

    We present a characterization of the metal-affinity driven self-assembly between luminescent CdSe-ZnS core-shell semiconductor quantum dots (QDs) and either peptides or proteins appended with various length terminal polyhistidine tags. We first monitor the kinetics of self-assembly between surface-immobilized QDs and proteins/peptides under flow conditions (immobilized). To accomplish this, the QDs were immobilized onto functionalized substrates and then exposed to dye-labeled peptides/proteins. By using evanescent wave excitation of the substrate, self-assembly was assessed by monitoring the time-dependent changes in the dye fluorescence. This configuration was complemented with experiments using freely diffusing QDs and proteins/peptides (solution-phase) via energy transfer between QDs and dye-labeled proteins/peptides. Cumulatively, these measurements allowed determination of kinetic parameters, including association and dissociation rates (k on and k off) and the binding constant (K d). We find that self-assembly is rapid with an equilibrium constant K d -1 in the low nM. We next demonstrate the importance of understanding this self-assembly by creating QD-peptide bioconjugates which we employ as substrates to monitor the cleavage activity of proteolytic enzymes. This confirms that metal-affinity interactions can provide QD-bioconjugates that are functional and stable.

  14. Synthesis, modification, bioconjugation of silica coated fluorescent quantum dots and their application for mycotoxin detection.

    Science.gov (United States)

    Goftman, Valentina V; Aubert, Tangi; Ginste, Dries Vande; Van Deun, Rik; Beloglazova, Natalia V; Hens, Zeger; De Saeger, Sarah; Goryacheva, Irina Yu

    2016-05-15

    To create bright and stable fluorescent biolabels for immunoassay detection of mycotoxin deoxynivalenol in food and feed, CdSe/CdS/ZnS core-shell quantum dots (QDs) were encapsulated in silica nanoparticles through a water-in-oil reverse microemulsion process. The optical properties and stability of the obtained silica coated QDs (QD@SiO2), modified with amino, carboxyl and epoxy groups and stabilized with polyethylene glycol fragments, were characterized in order to assess their bioapplicability. The developed co-condensation techniques allowed maintaining 80% of the initial fluorescent properties and yielded stable fluorescent labels that could be easily activated and bioconjugated. Further, the modified QD@SiO2 were efficiently conjugated with antibodies and applied as a novel label in a microtiter plate based immunoassay and a quantitative column-based rapid immunotest for deoxynivalenol detection with IC50 of 473 and 20 ng/ml, respectively. PMID:26745794

  15. Interface states and bio-conjugation of CdSe/ZnS core-shell quantum dots

    Science.gov (United States)

    Torchynska, T. V.

    2009-03-01

    The paper presents the results of photoluminescence (PL) and Raman scattering studies of non-conjugated and bio-conjugated CdSe/ZnS core-shell quantum dots (QDs). The commercial CdSe/ZnS QDs used are characterized by color emission with maxima at 605-610 nm (2.03-2.05 eV). PL spectra of non-conjugated QDs are the superposition of PL bands related to exciton emission in the CdSe core (2.03-2.05 eV) and to hot electron-hole emission via defect states at the CdSe/ZnS interface (2.37 and 2.68 eV). QD conjugation was performed with biomolecules—the antihuman interleukin 10 antibody (antihuman IL10). The PL spectra of bio-conjugated QDs have been changed dramatically: only one PL band related to exciton emission in the CdSe core was detected in bio-conjugated QDs. To explain this effect a model has been proposed which assumes that the QD bio-conjugation process is accompanied by the recharging of acceptor-like interface states at the CdSe/ZnS interface. A comparative analysis of normalized PL spectra of non-conjugated CdSe/ZnS QDs with different intensities of interface state PL has confirmed the proposed electron-hole recombination model in QDs.

  16. Tensile-strained GaAsN quantum dots on InP

    OpenAIRE

    Pohjola, P.; Hakkarainen, T.; Koskenvaara, H.; Sopanen, Markku; Lipsanen, Harri; Sainio, J.

    2007-01-01

    Self-assembled quantum dots are typically fabricated from compressive-strained material systems, e.g., InAs on GaAs. In this letter, self-assembled quantum dots from tensile-strained GaAsN on InP are demonstrated. GaAsN on InP has type-I band alignment. Stranski-Krastanov growth mode is not observed, but in situannealing of the uncapped samples results in the formation of islands. Photoluminescence spectra from the buried GaAsN show separate peaks due to a wetting layer and islands around the...

  17. Synthesis of colloidal InP nanocrystal quantum dots

    International Nuclear Information System (INIS)

    InP nano dots with the diameter of 4-10 nm were synthesized using sol-gel method. The nano dot dimensions were obtained using TEM, and we found the d(111) spacing to be 0.328 nm which agrees within 3% of the literature value. Prepared nanoparticles where characterized then by Raman spectroscopy and Xray diffraction. Performed measurements confirm good crystalline quality of obtained InP particles, which can be used as a basis for THz emitters, LED, and OLED displays. (authors)

  18. Self-assembled luminescent CdSe-ZnS quantum dot bioconjugates prepared using engineered poly-histidine terminated proteins

    International Nuclear Information System (INIS)

    We report a simple and versatile approach for the conjugation of luminescent CdSe-ZnS core-shell quantum dots (QDs) to proteins through coordination of engineered C-terminal oligohistidine sequences. Several histidine tail containing proteins were self-assembled onto the QD surface using this method. A recombinant antibody specific for the high explosive 2,4,6-trinitrotoluene (TNT) was conjugated to QDs through a carboxy terminal histidine tail and the bioconjugate used to detect TNT by competitive immunoassay. TNT was detected over the range of 10 μg/ml down to 41 ng/ml using the scFv conjugated to QDs. These results open up the possibility to conjugate luminescent QDs to a whole range of proteins to form QD bioconjugates that can be effectively used in bio-oriented applications, such as sensing, imaging, immunoassay and other diagnostics

  19. Modeling on the size dependent properties of InP quantum dots: a hybrid functional study

    International Nuclear Information System (INIS)

    Theoretical calculations based on density functional theory were performed to provide better understanding of the size dependent electronic properties of InP quantum dots (QDs). Using a hybrid functional approach, we suggest a reliable analytical equation to describe the change of energy band gap as a function of size. Synthesizing colloidal InP QDs with 2–4 nm diameter and measuring their optical properties was also carried out. It was found that the theoretical band gaps showed a linear dependence on the inverse size of QDs and gave energy band gaps almost identical to the experimental values. (paper)

  20. Synthesis and characterization of InP and InN colloidal quantum dots.

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.; Osinski, Marek (University of New Mexico, Albuquerque, New Mexico); Greenberg, Melisa (University of New Mexico, Albuquerque, New Mexico); Bunge, Scott D.; Chen, Weiliang (University of New Mexico, Albuquerque, New Mexico); Smolyakov, G. A. (University of New Mexico, Albuquerque, New Mexico); Pulford, B. N. (University of New Mexico, Albuquerque, New Mexico); Jiang, Ying-Bing (University of New Mexico, Albuquerque, New Mexico)

    2005-04-01

    InP quantum dots (QDs) with zinc blende structure and InN QDs with hexagonal structure were synthesized from appropriate organometallic precursors in a noncoordinating solvent using myristic acid as a ligand. The QDs were characterized by TEM, the associated energy dispersive spectroscopy (EDS), electron diffraction, and steady state UV-VIS optical absorption and photoluminescence spectroscopy. To our best knowledge, this paper reports synthesis of InN colloidal quantum dots for the first time.

  1. Effect of nuclear spins on the electron spin dynamics in negatively charged InP quantum dots

    OpenAIRE

    Ignatiev, I. V.; Verbin, S. Yu.; Gerlovin, I. Ya.; Maruyama, W.; Pal, B.; Masumoto, Y.

    2005-01-01

    Kinetics of polarized photoluminescence of the negatively charged InP quantum dots in weak magnetic field is studied experimentally. Effect of both the nuclear spin fluctuations and the dynamical nuclear polarization on the electron spin orientation is observed.

  2. Formation of quantum wires and dots on InP(001) by As/P exchange

    International Nuclear Information System (INIS)

    We report on the use of in situ scanning tunneling microscopy to study As/P exchange on InP(001) surfaces by molecular beam epitaxy. Results demonstrate that the exchange process can be controlled to selectively produce either quantum wires or quantum dots. 15 nm wide self-assembled nanowires are observed, and they are elongated along the dimer row direction of the InP(001)-2x4 surface with a length of over 1 μm and flat top 2x4 surfaces. In addition, when the nanowires are annealed with no arsenic overpressure, the surface reconstruction transforms from 2x4 to 4x2 and the nanowires transform into dots with a rectangular base and flat top. [copyright] 2001 American Institute of Physics

  3. The detection of platelet derived growth factor using decoupling of quencher-oligonucleotide from aptamer/quantum dot bioconjugates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gang-Il; Sung, Yun-Mo [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Kyung-Woo; Oh, Min-Kyu [Department of Chemical and Biological Engineering, Korea University, Seoul 136-713 (Korea, Republic of)], E-mail: mkoh@korea.ac.kr, E-mail: ymsung@korea.ac.kr

    2009-04-29

    High-sensitivity, high-specificity detection of platelet derived growth factor (PDGF)-BB was realized using the change in fluorescence resonance energy transfer (FRET) occurring between quantum dot (QD) donors and black hole quencher (BHQ) acceptors. CdSe/ZnS QD/mercaptoacetic acid (MAA)/PDGF aptamer bioconjugates were successfully synthesized using ligand exchange. Black hole quencher (BHQ)-bearing oligonucleotide molecules showing partial sequence matching to PDGF aptamer were attached to PDGF aptamers and photoluminescence (PL) quenching was obtained through FRET. By adding target PDGF-BB to the bioconjugates containing BHQs, PL recovery was detected due to detachment of BHQ-bearing oligonucleotide from the PDGF aptamer as a result of the difference in affinity to the PDGF aptamer. The detection limit of the sensor was {approx}0.4 nM and the linearity was maintained up to 1.6 nM in the PL intensity versus concentration curve. Measurement of PL recovery was suggested as a strong tool for high-sensitivity detection of PDGF-BB. Epidermal growth factor (EGF), the negative control molecule, did not contribute to PL recovery due to lack of binding affinity to the PDGF aptamers, which demonstrates the selectivity of the biosensor.

  4. Wide bandgap, strain-balanced quantum well tunnel junctions on InP substrates

    Science.gov (United States)

    Lumb, M. P.; Yakes, M. K.; González, M.; Bennett, M. F.; Schmieder, K. J.; Affouda, C. A.; Herrera, M.; Delgado, F. J.; Molina, S. I.; Walters, R. J.

    2016-05-01

    In this work, the electrical performance of strain-balanced quantum well tunnel junctions with varying designs is presented. Strain-balanced quantum well tunnel junctions comprising compressively strained InAlAs wells and tensile-strained InAlAs barriers were grown on InP substrates using solid-source molecular beam epitaxy. The use of InAlAs enables InP-based tunnel junction devices to be produced using wide bandgap layers, enabling high electrical performance with low absorption. The impact of well and barrier thickness on the electrical performance was investigated, in addition to the impact of Si and Be doping concentration. Finally, the impact of an InGaAs quantum well at the junction interface is presented, enabling a peak tunnel current density of 47.6 A/cm2 to be realized.

  5. Quantum confinement and ultrafast dephasing dynamics in InP nanocrystals

    International Nuclear Information System (INIS)

    The electronic level structure and dephasing dynamics of InP nanocrystals in the strong quantum-confinement regime are studied by two complementary techniques: nanosecond hole burning and the femtosecond three-pulse photon echo. Hole burning yields the homogeneous electronic level structure while the photon echo allows the extraction of the linewidth of the band-gap transition. The congestion of electronic levels observed close to the band-edge transition in the hole-burning experiments gives rise to a pulse-width-limited initial decay in the photon-echo signal. The level structure is calculated and assigned using a model which includes valence-band mixing. The homogeneous linewidth of the band-edge transition is approximately 5 meV at 20 K and is broadened considerably at higher temperatures. The temperature dependence of the linewidth is consistent with an intrinsic dephasing mechanism of coupling to low-frequency acoustic modes mediated by the deformation potential. Quantum-confinement effects in III-V semiconductor InP are compared to those of the prototypical CdSe II-VI semiconductor nanocrystal system. copyright 1997 The American Physical Society

  6. Semiquantitative fluorescence method for bioconjugation analysis.

    Science.gov (United States)

    Brasil, Aluízio G; Carvalho, Kilmara H G; Leite, Elisa S; Fontes, Adriana; Santos, Beate Saegesser

    2014-01-01

    Quantum dots (QDs) have been used as fluorescent probes in biological and medical fields such as bioimaging, bioanalytical, and immunofluorescence assays. For these applications, it is important to characterize the QD-protein bioconjugates. This chapter provides details on a versatile method to confirm quantum dot-protein conjugation including the required materials and instrumentation in order to perform the step-by-step semiquantitative analysis of the bioconjugation efficiency by using fluorescence plate readings. Although the protocols to confirm the QD-protein attachment shown here were developed for CdTe QDs coated with specific ligands and proteins, the principles are the same for other QDs-protein bioconjugates. PMID:25103803

  7. Cellular trafficking of quantum dot-ligand bioconjugates and their induction of changes in normal routing of unconjugated ligands

    DEFF Research Database (Denmark)

    Tekle, Christina; van Deurs, Bo; Sandvig, Kirsten; Iversen, Tore-Geir

    2008-01-01

    visualized in the Golgi apparatus. Importantly, we find that the endosomal accumulation of ricin:Qdots affects endosome-to-Golgi transport of both ricin and Shiga toxin: Transport of ricin was reduced whereas transport of Shiga toxin was increased. In conclusion, the data reveal that, although coupling of......:Qdots were internalized by clathrin-dependent endocytosis as fast as Tf, but their recycling was blocked. Unlike Shiga toxin, the Shiga:Qdot bioconjugate was not routed to the Golgi apparatus. The internalized ricin:Qdot bioconjugates localized to the same endosomes as ricin itself but could not be...

  8. Fabrication of InAs quantum dot stacked structure on InP(311)B substrate by digital embedding method

    Science.gov (United States)

    Akahane, Kouichi; Yamamoto, Naokatsu; Kawanishi, Tetsuya

    2015-12-01

    Self-assembled InAs quantum dots (QDs) grown on an InP(311)B substrate were embedded using lattice-matched InAlAs/InGaAs superlattice with the digital embedding method. The thickness of quantum wells and barriers of the superlattice varied from 2 to 16 monolayers. The six layer stacking structures were successfully grown without any degradation of the QD and superlattice structure. The cross-sections of QDs embedded within the superlattice were visualized by scanning transmission microscope. The emission wavelength of the QDs was measured by photoluminescence and could be changed by changing the thickness of the superlattice.

  9. Bioconjugation of luminescent silicon quantum dots to gadolinium ions for bioimaging applications

    Science.gov (United States)

    Erogbogbo, Folarin; Chang, Ching-Wen; May, Jasmine L.; Liu, Liwei; Kumar, Rajiv; Law, Wing-Cheung; Ding, Hong; Yong, Ken Tye; Roy, Indrajit; Sheshadri, Mukund; Swihart, Mark T.; Prasad, Paras N.

    2012-08-01

    Luminescent imaging agents and MRI contrast agents are desirable components in the rational design of multifunctional nanoconstructs for biological imaging applications. Luminescent biocompatible silicon quantum dots (SiQDs) and gadolinium chelates can be applied for fluorescence microscopy and MRI, respectively. Here, we report the first synthesis of a nanocomplex incorporating SiQDs and gadolinium ions (Gd3+) for biological applications. The nanoconstruct is composed of a PEGylated micelle, with hydrophobic SiQDs in its core, covalently bound to DOTA-chelated Gd3+. Dynamic light scattering reveals a radius of 85 nm for these nanoconstructs, which is consistent with the electron microscopy results depicting radii ranging from 25 to 60 nm. Cellular uptake of the probes verified that they maintain their optical properties within the intracellular environment. The magnetic resonance relaxivity of the nanoconstruct was 2.4 mM-1 s-1 (in terms of Gd3+ concentration), calculated to be around 6000 mM-1 s-1 per nanoconstruct. These desirable optical and relaxivity properties of the newly developed probe open the door for use of SiQDs in future multimodal applications such as tumour imaging.Luminescent imaging agents and MRI contrast agents are desirable components in the rational design of multifunctional nanoconstructs for biological imaging applications. Luminescent biocompatible silicon quantum dots (SiQDs) and gadolinium chelates can be applied for fluorescence microscopy and MRI, respectively. Here, we report the first synthesis of a nanocomplex incorporating SiQDs and gadolinium ions (Gd3+) for biological applications. The nanoconstruct is composed of a PEGylated micelle, with hydrophobic SiQDs in its core, covalently bound to DOTA-chelated Gd3+. Dynamic light scattering reveals a radius of 85 nm for these nanoconstructs, which is consistent with the electron microscopy results depicting radii ranging from 25 to 60 nm. Cellular uptake of the probes verified that they

  10. Assembly and intracellular delivery of quantum dot-fluorescent protein bioconjugates

    Science.gov (United States)

    Medintz, Igor L.; Pons, Thomas; Delehanty, James B.; Susumu, Kimihiro; Dawson, Philip E.; Mattoussi, Hedi

    2008-02-01

    We have previously assembled semiconductor quantum dot (QD)-based fluorescence resonance energy transfer (FRET) sensors that can specifically detect nutrients, explosives or enzymatic activity. These sensors utilized the inherent benefits of QDs as FRET donors to optimize signal transduction. In this report we functionalize QDs with the multi-subunit multi-chromophore b-phycoerythrin (b-PE) light harvesting complex using biotin-Streptavidin binding. FRET and gel electrophoretic analyses were used to characterize and confirm the QD-b-PE self-assembly. We found that immobilizing additional cell-penetrating peptides on the nanocrystal surface along with the b-PE was the key factor allowing the mixed surface QD-cargos to undergo endocytosis and intracellular delivery. Our findings on the intracellular uptake promoted by CPP were compared to those collected using microinjection technique, where QD-assemblies were delivered directly into the cytoplasm; this strategy allows bypassing of the endocytic uptake pathway. Intracellular delivery of multifunctional QD-fluorescent protein assemblies has potential applications for use in protein tracking, sensing and diagnostics.

  11. Monitoring Enzymatic Proteolysis Using Either Enzyme- or Substrate-Bioconjugated Quantum Dots.

    Science.gov (United States)

    Díaz, S A; Breger, J C; Medintz, I L

    2016-01-01

    Rational design of enzyme-nanoparticle hybrids is still in its infancy and the design is often inspired by potential access to many beneficial sensing properties such as increased stability, sensitivity, and even enhanced enzyme activities in specific cases. Deriving quantitative kinetic data from these constructs is not trivial, however, since the intrinsic design gives rise to unique properties that can influence the enzymatic assays that are central to the application of the hybrids. Here, we present two distinct assay methodologies for following the kinetic activity of composite enzyme-nanoparticle constructs. We utilize luminescent semiconductor nanocrystals or quantum dots (QDs) as the prototypical nanoparticulate platform for these sensing formats and target proteolytic enzyme activity as the main assay. The first assay is analogous to most current enzymatic assays and is designed to compare QD-enzyme constructs; this format is based on utilizing a fixed concentration of enzyme displayed on the QD and excess substrate in the solution, and the analysis utilizes data from initial velocities. The second assay is designed to analyze kinetics using a QD-substrate construct, in which the enzyme and QD interactions are short lived. Here, the nanoparticle-substrate concentration is held constant and exposed to increasing concentrations of the enzyme in solution. This later methodology is based on a fluorescent ratiometric signal that follows the entire progress curve of the enzyme reaction. A comparison of these two different assays of the series of enzyme-nanoparticle and substrate-nanoparticle constructs provides deeper insight into the enzyme kinetics of these hybrids, while still testing of individual variables within a given format, to allow for further optimization within each set. PMID:27112393

  12. Growing InGaAs quasi-quantum wires inside semi-rhombic shaped planar InP nanowires on exact (001) silicon

    Science.gov (United States)

    Han, Yu; Li, Qiang; Chang, Shih-Pang; Hsu, Wen-Da; Lau, Kei May

    2016-06-01

    We report InGaAs quasi-quantum wires embedded in planar InP nanowires grown on (001) silicon emitting in the 1550 nm communication band. An array of highly ordered InP nanowire with semi-rhombic cross-section was obtained in pre-defined silicon V-grooves through selective-area hetero-epitaxy. The 8% lattice mismatch between InP and Si was accommodated by an ultra-thin stacking disordered InP/GaAs nucleation layer. X-ray diffraction and transmission electron microscope characterizations suggest excellent crystalline quality of the nanowires. By exploiting the morphological evolution of the InP and a self-limiting growth process in the V-grooves, we grew embedded InGaAs quantum-wells and quasi-quantum-wires with tunable shape and position. Room temperature analysis reveals substantially improved photoluminescence in the quasi-quantum wires as compared to the quantum-well reference, due to the reduced intrusion defects and enhanced quantum confinement. These results show great promise for integration of III-V based long wavelength nanowire lasers on the well-established (001) Si platform.

  13. Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results.

    Science.gov (United States)

    Barettin, Daniele; De Angelis, Roberta; Prosposito, Paolo; Auf der Maur, Matthias; Casalboni, Mauro; Pecchia, Alessandro

    2014-05-16

    We report on numerical simulations of a zincblende InP surface quantum dot (QD) on In₀.₄₈Ga₀.₅₂ buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, [Formula: see text] bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband [Formula: see text] approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental

  14. Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results

    International Nuclear Information System (INIS)

    We report on numerical simulations of a zincblende InP surface quantum dot (QD) on In0.48Ga0.52P buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, k-vector ⋅ p-vector bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband k-vector ⋅ p-vector approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental

  15. Thermal conductivity of InAs quantum dot stacks using AlAs strain compensating layers on InP substrate

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Folliot, H., E-mail: herve.folliot@insa-rennes.fr [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Le Pouliquen, J.; Chevalier, N.; Rohel, T.; Paranthoeen, C.; Bertru, N. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Labbe, C. [CIMAP, CEA/UMR CNRS 6252/ENSICAEN/Universite de Caen Basse Normandie, 6, Boulevard Marechal Juin, 14050 Caen Cedex 4 (France); Letoublon, A.; Le Corre, A. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France)

    2012-06-25

    Highlights: Black-Right-Pointing-Pointer The thermal conductivity of InAs on InP (1 1 3)B quantum dots stacks is measured. Black-Right-Pointing-Pointer The growth of a close stack of 100 layers of InAs using AlAs strain compensating layers is presented. Black-Right-Pointing-Pointer New data on the thermal conductivity of InP n-doped susbtrate are given. - Abstract: The growth and thermal conductivity of InAs quantum dot (QD) stacks embedded in GaInAs matrix with AlAs compensating layers deposited on (1 1 3)B InP substrate are presented. The effect of the strain compensating AlAs layer is demonstrated through Atomic Force Microscopy (AFM) and X-ray diffraction structural analysis. The thermal conductivity (2.7 W/m K at 300 K) measured by the 3{omega} method reveals to be clearly reduced in comparison with a bulk InGaAs layer (5 W/m K). In addition, the thermal conductivity measurements of S doped InP substrates and the SiN insulating layer used in the 3{omega} method in the 20-200 Degree-Sign C range are also presented. An empirical law is proposed for the S doped InP substrate, which slightly differs from previously presented results.

  16. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    International Nuclear Information System (INIS)

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In0.48Ga0.52 P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k→·p→ bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots

  17. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    Energy Technology Data Exchange (ETDEWEB)

    Barettin, Daniele, E-mail: Daniele.Barettin@uniroma2.it; Auf der Maur, Matthias [Department of Electronic Engineering, University of Rome “Tor Vergata,” Via del Politecnico 1, 00133, Rome (Italy); De Angelis, Roberta; Prosposito, Paolo; Casalboni, Mauro [Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1 00133 Rome, Italy and INSTM, Unitá di ricerca dell' Universitá di Roma “Tor Vergata,” Via della Ricerca Scientifica 1, 00133, Rome (Italy); Pecchia, Alessandro [CNR-ISMN, via Salaria Km. 29.300, 00017 Monterotondo, Rome (Italy)

    2015-03-07

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In{sub 0.48}Ga{sub 0.52 }P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k{sup →}·p{sup →} bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots.

  18. Many-body pseudopotential theory of excitons in InP and CdSe quantum dots

    International Nuclear Information System (INIS)

    We present a pseudopotential approach to the calculation of the excitonic spectrum of semiconductor quantum dots. Starting from a many-body expansion of the exciton wave functions in terms of single-substitution Slater determinants constructed from pseudopotential single-particle wave functions, our method permits an accurate and detailed treatment of the intraconfiguration electron-hole Coulomb and exchange interactions, while correlation effects can be included in a controlled fashion by allowing interconfiguration coupling. We calculate the exciton fine structure of InP and CdSe nanocrystals in the strong-confinement regime. We find a different size dependence for the electron-hole exchange interaction than previously assumed (i.e., R-2 instead of R-3). Our calculated exciton fine structure is compared with recent experimental results obtained by size-selective optical spectroscopies. copyright 1999 The American Physical Society

  19. Bioconjugation of CdTe quantum dot for the detection of 2,4-dichlorophenoxyacetic acid by competitive fluoroimmunoassay based biosensor.

    Science.gov (United States)

    Vinayaka, A C; Basheer, S; Thakur, M S

    2009-02-15

    Quantum dots (QD) are semiconductor fluorescent nanoparticles, which can be made use of for environmental monitoring with high sensitivity. In view of the alarming levels of pesticides and herbicides being used in agriculture practices, there is a need for their rapid, sensitive and specific detection in food and environmental samples, as pesticides and herbicides are harmful to living beings even at trace levels. Present study was carried out to develop a reliable and rapid method for analysis and detection of 2,4-D (herbicide) using cadmium telluride quantum dot nanoparticle (CdTe QD). Fluoroimmunoassay based on the fluorescent property of quantum dot was used along with immunoassay to detect 2,4-D. CdTe capped with mercaptopropionic acid, was conjugated using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and a coupling reagent like N-hydroxysuccinimide (NHS) to alkaline phosphatase (ALP) which was in turn conjugated to 2,4-D molecule. Anti 2,4-D-IgG antibodies were immobilized in an immunoreactor column using Sepharose CL-4B as an inert matrix. The detection of 2,4-D was carried out by fluoroimmunoassay-based biosensor using competitive binding between conjugated 2,4-D-ALP-CdTe and free 2,4-D with immobilized anti 2,4-D antibodies in an immunoreactor column. It was possible to detect 2,4-D upto 250pgmL(-1). Present study also emphasizes on the resonance energy transfer between ALP and CdTe QD as a result of bioconjugation, which can be used for future biosensor development based on quantum dot-biomolecular interactions. PMID:18930650

  20. The role of strain-driven in migration in the growth of self-assembled InAs quantum dots on InP

    CERN Document Server

    Yoon, S H; Lee, T W; Hwang, H D; Yoon, E J; Kim, Y D

    1999-01-01

    Self-assembled InAs quantum dots (SAQDs) were grown on InP by metalorganic chemical vapor deposition. The amount of excess InAs and the aspect ratio of the SAQD increased with temperature and V/III ratio. It is explained that the As/P exchange reaction at the surface played an important role in the kinetics of SAQD formation. Insertion of a lattice-matched InGaAs buffer layer suppressed the excess InAs formation, and lowered the aspect ratio. Moreover, the dots formed on InGaAs buffer layers were faceted, whereas those on InP were hemispherical, confirming the effect of the As/P exchange reaction. The shape of InAs quantum dots on InGaAs buffer layers was a truncated pyramid with four [136] facets and base edges parallel to directions.

  1. Electrical properties of self-assembled InAs/InAlAs quantum dots on InP

    International Nuclear Information System (INIS)

    The characteristics of InAs self-assembled quantum dots (QDs) grown on InAlAs/InP (0 0 1) have been investigated by capacitance–voltage (C–V) measurements and deep-level transient spectroscopy (DLTS). The depth profile of the apparent electron concentration obtained by C–V measurements shows significant carrier accumulation around the position of the InAs QDs plane. In addition to the D1–D5 traps, which are commonly detected in InAlAs layers grown on InP by molecular beam epitaxy (MBE), DLTS investigations show three InAs-related levels located at about 76, 202 and 246 meV below the InAlAs conduction band edge. The applied field is found to significantly enhance tunnel emission processes as seen in the broadening of the peaks with increasing reverse bias. The results suggest that defects in the material barrier can enhance electron tunnelling through barriers

  2. 1.55 μm InAs quantum dot distribution on truncated InP pyramids and regrowth by selective area epitaxy

    International Nuclear Information System (INIS)

    Position and distribution control of 1.55-μm InAs quantum dots (QDs) on truncated InP pyramids grown by selective area Metal Organic Vapor Phase Epitaxy (MOVPE) is reported. The arrangement of the {103}, {115}, and (100) facets on the pyramid top surface is governed by the shape of the pyramid base and top surface area. This allows the precise position and distribution control of the QDs due to preferential nucleation on the {103} and {115} facets. With shrinking QD number upon reduced top surface area, sharp emission from single QDs is observed at 1.55 μm. Regrowth of a passive InP structure around the pyramids establishes submicrometer-scale active-passive integration for efficient microcavity QD nanolasers and single photon sources operating in the 1.55-μm telecom wavelength region and their implementation in photonic integrated circuits.

  3. Synthesis and enzymatic photo-activity of an O2 tolerant hydrogenase-CdSe@CdS quantum rod bioconjugate.

    Science.gov (United States)

    Hamon, C; Ciaccafava, A; Infossi, P; Puppo, R; Even-Hernandez, P; Lojou, E; Marchi, V

    2014-05-21

    This communication reports on the preparation of stable and photo-active nano-heterostructures composed of O2 tolerant [NiFe] hydrogenase extracted from the Aquifex aeolicus bacterium grafted onto hydrophilic CdSe/CdS quantum rods in view of the development of H2/O2 biofuel cells. The resulting complex is efficient towards H2 oxidation, displays good stability and new photosensitive properties. PMID:24468861

  4. Solubilization and Bio-conjugation of Quantum Dots and Bacterial Toxicity Assays by Growth Curve and Plate Count

    OpenAIRE

    Park, Soonhyang; Chibli, Hicham; Nadeau, Jay

    2012-01-01

    Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence1,2 3,4,5. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells6.

  5. Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties

    OpenAIRE

    Niko Hildebrandt; Blanco-Canosa, Juan B.; Dawson, Philip E.; Stewart, Michael H.; Kimihiro Susumu; W. Russ Algar; Frank Morgner; Igor L. Medintz; Daniel Geißler; Stefan Stufler

    2011-01-01

    Förster resonance energy transfer (FRET) from luminescent terbium complexes (LTC) as donors to semiconductor quantum dots (QDs) as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinic...

  6. An accurate description of quantum size effects in InP nanocrystallites over a wide range of sizes

    International Nuclear Information System (INIS)

    We obtain an effective parametrization of the bulk electronic structure of InP within the tight-binding scheme. Using these parameters, we calculate the electronic structure of InP clusters with the size ranging up to 7.5 nm. The calculated variations in the electronic structure as a function of the cluster size is found to be in excellent agreement with experimental results over the entire range of sizes, establishing the effectiveness and transferability of the obtained parameter strengths

  7. 基于元素磷源的InP量子点的制备%Synthesis of InP Quantum Dots with Elemental Phosphine Source

    Institute of Scientific and Technical Information of China (English)

    王彬彬; 王莉; 汪瑾; 蒋阳

    2012-01-01

    The InP quantum dots (QDs) were synthesized via a colloidal chemical method with white phosphorus (P4), indium acetate (In (Ac)3), stearic acid and 1-octadecene (ODE) as phosphorus source, indium source, surfactant and solvent, respectively. The structure, size and shape of the quantum dots were analyzed by XRD and TEM. The resulting InP QDs were also characterized by UV-Visible absorption and fluorescence spectroscopy. The title material exhibits well-resolved absorption and emission properties. Meanwhile, the InP QDs emit at 415~517 nm in the electromagnetic spectrum showing obvious quantum size effect.%以白磷作为磷源、醋酸铟为铟源、硬脂酸为表面包覆剂、十八烯为溶剂,采用胶体化学法合成了InP量子点.X射线衍射(XRD)和透射电子显微镜(TEM)分析测试显示InP量子点属于立方闪锌矿结构,并且是直径约为5 nm的球状纳米晶.紫外可见光谱和荧光光谱分析表明,InP量子点表现出明显的激子吸收和带边发射特征,荧光发射光谱在415~517 nm范围内连续可调,呈现明显的量子尺寸效应.

  8. Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties

    Directory of Open Access Journals (Sweden)

    Niko Hildebrandt

    2011-10-01

    Full Text Available Förster resonance energy transfer (FRET from luminescent terbium complexes (LTC as donors to semiconductor quantum dots (QDs as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma.

  9. Bio-conjugated luminescent quantum dots of doped ZnS: a cyto-friendly system for targeted cancer imaging

    International Nuclear Information System (INIS)

    A heavy-metal-free luminescent quantum dot (QD) based on doped zinc sulfide (ZnS), conjugated with a cancer-targeting ligand, folic acid (FA), is presented as a promising bio-friendly system for targeted cancer imaging. Doped QDs were prepared by a simple aqueous method at room temperature. X-ray diffraction and transmission electron microscopy studies showed the formation of monodisperse QDs of average size ∼4 nm with cubic (sphalerite) crystal structure. Doping of the QDs with metals (Al3+), transition metals (Cu+, Mn2+) and halides (F-) resulted in multi-color emission with dopant-specific color tunability ranging from blue (480 nm) to red (622 nm). Luminescent centers in doped QDs could be excited using bio-friendly visible light >400 nm by directly populating the dopant centers, leading to bright emission. The cytotoxicity of bare and FA conjugated QDs was tested in vitro using normal lung fibroblast cell line (L929), folate-receptor-positive (FR+) nasopharyngeal epidermoid carcinoma cell line (KB), and FR-negative (FR-) lung cancer cell line (A549). Both bare and FA-conjugated ZnS QDs elicited no apparent toxicity even at high concentrations of ∼100 μM and 48 h of incubation. In contrast, CdS QDs prepared under identical conditions showed relatively high toxicity even at low concentrations of ∼0.1 μM and 24 h of incubation. Interaction of FA-QDs with different cell lines showed highly specific attachment of QDs in the FR+ cancer cell line, leaving others unaffected. The bright and stable luminescence of the QDs could be used to image both single cancer cells and colonies of cancer cells without affecting their metabolic activity and morphology. Thus, this study presents, for the first time, the use of non-toxic, Cd-, Te-, Se-, Pb- and Hg-free luminescent QDs for targeted cancer imaging.

  10. Bio-conjugated luminescent quantum dots of doped ZnS: a cyto-friendly system for targeted cancer imaging

    Science.gov (United States)

    Manzoor, Koyakutty; Johny, Seby; Thomas, Deepa; Setua, Sonali; Menon, Deepthy; Nair, Shantikumar

    2009-02-01

    A heavy-metal-free luminescent quantum dot (QD) based on doped zinc sulfide (ZnS), conjugated with a cancer-targeting ligand, folic acid (FA), is presented as a promising bio-friendly system for targeted cancer imaging. Doped QDs were prepared by a simple aqueous method at room temperature. X-ray diffraction and transmission electron microscopy studies showed the formation of monodisperse QDs of average size ~4 nm with cubic (sphalerite) crystal structure. Doping of the QDs with metals (Al3+), transition metals (Cu+, Mn2+) and halides (F-) resulted in multi-color emission with dopant-specific color tunability ranging from blue (480 nm) to red (622 nm). Luminescent centers in doped QDs could be excited using bio-friendly visible light >400 nm by directly populating the dopant centers, leading to bright emission. The cytotoxicity of bare and FA conjugated QDs was tested in vitro using normal lung fibroblast cell line (L929), folate-receptor-positive (FR+) nasopharyngeal epidermoid carcinoma cell line (KB), and FR-negative (FR-) lung cancer cell line (A549). Both bare and FA-conjugated ZnS QDs elicited no apparent toxicity even at high concentrations of ~100 µM and 48 h of incubation. In contrast, CdS QDs prepared under identical conditions showed relatively high toxicity even at low concentrations of ~0.1 µM and 24 h of incubation. Interaction of FA-QDs with different cell lines showed highly specific attachment of QDs in the FR+ cancer cell line, leaving others unaffected. The bright and stable luminescence of the QDs could be used to image both single cancer cells and colonies of cancer cells without affecting their metabolic activity and morphology. Thus, this study presents, for the first time, the use of non-toxic, Cd-, Te-, Se-, Pb- and Hg-free luminescent QDs for targeted cancer imaging.

  11. Ultra-broadband Superradiant Pulses from Femtosecond Laser Pumped InP based Quantum Well Laser Diode

    Science.gov (United States)

    Liu, Jingjing

    Laser techniques, such as gain / Q switching, mode-locking, have successfully overcome the energy restriction of gain clamping in the stead-state operated lasers, and allowed the generation of giant pulses with short pulse durations. However, gain saturation further limits the amount of stored energy in a gain medium, and therefore limits the possible maximum pulse energy obtained by laser techniques. Here we circumvent both gain clamping and the capacity limitation of energy storage by operating the double-quantum-well laser diode chips on ultrafast gain-switching model using femtosecond (fs) laser pulses as the optical pump. The advantage of our pumping approach is that the fs pulse can instantly produce a very large number of carriers, and therefore enable the formation of non-equilibrium coherent e-h BCS-like condensate state in a large energy region from the lowest QW subband edges to the highest subband and then obtain the ultra-broadband superradiant pulses. Superradiance (SR) or the coherent spontaneous emission is not a new quantum optics phenomenon, which has been proposed in 1954 by R. Dicke, even earlier than the invention of laser. It is famous as by its ultrashort duration, high peak power, high coherence and high timing jitter. Recently, femtosecond SR pulses have been generated from semiconductors. This investigation has revived both theoretical and experimental studies of SR emission. In this thesis, we have demonstrated the generation of intense, delayed SR pulses from the InP based double quantum well laser diode at room temperature. The 1040 nm femtosecond laser was applied as the optical pumping source, and when the pump power is high enough, the cooperative recombination of e-h pairs from higher order quantum energy levels can occur to generate SR bursts earlier than the cooperative emission from the lower quantum energy levels. Then, ultra-broadband TM polarized SR pulses have been firstly generated at room temperature. Our experiments also

  12. A quantum entropy source on an InP photonic integrated circuit for random number generation

    CERN Document Server

    Abellan, Carlos; Domenech, David; Muñoz, Pascual; Capmany, Jose; Longhi, Stefano; Mitchell, Morgan W; Pruneri, Valerio

    2016-01-01

    Random number generators are essential to ensure performance in information technologies, including cryptography, stochastic simulations and massive data processing. The quality of random numbers ultimately determines the security and privacy that can be achieved, while the speed at which they can be generated poses limits to the utilisation of the available resources. In this work we propose and demonstrate a quantum entropy source for random number generation on an indium phosphide photonic integrated circuit made possible by a new design using two-laser interference and heterodyne detection. The resulting device offers high-speed operation with unprecedented security guarantees and reduced form factor. It is also compatible with complementary metal-oxide semiconductor technology, opening the path to its integration in computation and communication electronic cards, which is particularly relevant for the intensive migration of information processing and storage tasks from local premises to cloud data centre...

  13. Photovoltaic conversion of visible spectrum by GaP capped InP quantum dots grown on Si (100) by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Growth of GaP capped strained InP quantum dots was carried out by metal organic chemical vapor deposition technique on Si (100) substrates to explore an alternative material system for photovoltaic conversion. Studies on reflectance spectroscopy show higher absorption of visible photons compared to scattering. Smooth and defect free interface provides low dark current with high rectification ratio. A solar cell made of five periods of quantum dots is found to provide a conversion efficiency of 4.18% with an open circuit voltage and short circuit current density of 0.52 V and 13.64 mA/cm2, respectively, under AM 1.5 solar radiation

  14. Characterization of multienzyme-antibody-carbon nanotube bioconjugates for immunosensors.

    Science.gov (United States)

    Jensen, Gary C; Yu, Xin; Gong, Joseph D; Munge, Bernard; Bhirde, Ashwin; Kim, Sang N; Papadimitrakopoulos, Fotios; Rusling, James F

    2009-01-01

    Characterization studies of a multi-enzyme-antibody-carbon nanotube bioconjugate designed for the amplification of electrochemical immunosensing are described. Secondary antibodies for prostate specific antigen (PSA) were covalently linked to highly carboxylated multi-walled carbon nanotube (CNT) along with multiple horseradish peroxidase (HRP) enzyme labels. These bioconjugates provide ultra-sensitive amperometric detection of PSA on a single-wall carbon nanotube forest sandwich immunosensor platform. A single layer of HRP on the surface of the CNT was suggested by images from atomic force microscopy (AFM) and transmission electron microscopy (TEM). HRP on the bioconjugate surface was visualized by confocal microscopy using in-situ HRP-catalyzed polymerization yielding a fluorescent product, and HRP activity was estimated in a conventional assay. Binding of quantum-dot labeled PSA to antibodies on the bioconjugate was used for visualization by TEM. Combining TEM and enzyme activity results gave estimates of approximately 82 HRPs and 30 +/- 15 secondary antibodies per 100 nm of antibody-HRP-CNT bioconjugate. PMID:19441303

  15. Epitaxial grown InP quantum dots on a GaAs buffer realized on GaP/Si(001) templates

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, Walter; Wiesner, Michael; Koroknay, Elisabeth; Paul, Matthias; Jetter, Michael; Michler, Peter [Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen und Research Center SCoPE, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

    2013-07-01

    The increasing necessity of higher computational capacity and security in the information technology requires originally technical solutions, which today's standard microelectronics, as their technical limits are close, can't provide anymore. One way out offers the integration of III-V semiconductor photonics with low-dimensional structures in current CMOS technology, enabling on-chip quantum optical applications, like quantum cryptography or quantum computing. Challenges in the heteroepitaxy of III-V semiconductors and silicon are the mismatches in material properties of the both systems. Defects, like dislocations and anti-phase domains (APDs), inhibit the monolithic integration of III-V semiconductor on Si. We present the growth of a thin GaAs buffer on CMOS-compatible oriented Si(001) by metal-organic vapor-phase epitaxy. To circumvent the forming APDs in the GaAs buffer a GaP on Si template (provided by NAsP{sub III/V} GmbH) was used. The dislocation density was then reduced by integrating several layers of InAs quantum dots in the GaAs buffer to bend the threading misfit dislocations. On top of this structure we grew InP quantum dots embedded in a Al{sub x}Ga{sub 1-x}InP composition and investigated the photoluminescence properties.

  16. Lyophilization of Semiconducting Polymer Dot Bioconjugates

    OpenAIRE

    Sun, Wei; Ye, Fangmao; Gallina, Maria E.; Yu, Jiangbo; Wu, Changfeng; Chiu, Daniel T.

    2013-01-01

    Semiconducting polymer dot (Pdot) bioconjugates are a new class of ultrabright fluorescent probes. Here, we report a procedure for lyophilizing Pdot bioconjugates so that they successfully retain their optical properties, colloidal stability, and cell-targeting capability during storage. We found that when Pdot bioconjugates were lyophilized in the presence of 10% sucrose, the rehydrated Pdot bioconjugates did not show any signs of aggregation and exhibited the same hydrodynamic diameters as ...

  17. Effect of band alignment on photoluminescence and carrier escape from InP surface quantum dots grown by metalorganic chemical vapor deposition on Si

    International Nuclear Information System (INIS)

    A detailed analysis of photoluminescence (PL) from InP quantum dots (QDs) grown on Si has been carried out to understand the effect of substrate/host material in the luminescence and carrier escape process from the surface quantum dots. Such studies are required for the development of monolithically integrated next generation III-V QD based optoelectronics with fully developed Si microelectronics. The samples were grown by atmospheric pressure metalorganic chemical vapor deposition technique, and the PL measurements were made in the temperature range 10–80 K. The distribution of the dot diameter as well as the dot height has been investigated from atomic force microscopy. The origin of the photoluminescence has been explained theoretically. The band alignment of InP/Si heterostructure has been determined, and it is found be type II in nature. The positions of the conduction band minimum of Si and the 1st excited state in the conduction band of InP QDs have been estimated to understand the carrier escape phenomenon. A blue shift with a temperature co-efficient of 0.19 meV/K of the PL emission peak has been found as a result of competitive effect of different physical processes like quantum confinement, strain, and surface states. The corresponding effect of blue shift by quantum confinement and strain as well as the red shift by the surface states in the PL peaks has been studied. The origin of the luminescence in this heterojunction is found to be due to the recombination of free excitons, bound excitons, and a transition from the 1st electron excited state in the conduction band (e1) to the heavy hole band (hh1). Monotonic decrease in the PL intensity due to increase of thermally escaped carriers with temperature has been observed. The change in barrier height by the photogenerated electric-field enhanced the capture of the carriers by the surface states rather than their accumulation in the QD excited state. From an analysis of the dependence of the PL

  18. Spectral and carrier transfer characteristics of 1.55 -μ m InAs /InP coupled-quantum-dot lasers

    Science.gov (United States)

    Lin, Zhiyuan; Wang, Zhuoran; Yuan, Guohui

    2015-07-01

    To explore the spectral and carrier transfer characteristics of 1.55 -μ m InAs /InP coupled-quantum-dot lasers (CQDLs), we develop a probabilistically coupled multipopulation rate equation model (PCMPREM) involving intradot and interdot relaxation, inhomogeneous broadening, and homogeneous broadening. After solving the PCMPREM with the fourth-order Runge-Kutta method, a simultaneous quadruple lasing spectrum is observed and explained by both the carrier competition theory and coupled theory. An analysis of the results shows that the coupling strength between different subbands changes with different current injections, giving a systematic understanding of the operation of CQDLs systems. With a lower threshold, the CQDL has a much broader output range of more than 105.3 nm around 1.55 μ m , which is 7.8 times greater than the uncoupled QDL, indicating that CQDLs can be excellent light sources for not only long-haul ultrahigh capacity optical communications, but also on-chip photonics integrated circuits with low power consumption.

  19. Study of ethanolamine surface treatment on the metal-oxide electron transport layer in inverted InP quantum dot light-emitting diodes

    Science.gov (United States)

    Jang, Ilwan; Kim, Jiwan; Park, Chang Jun; Ippen, Christian; Greco, Tonino; Oh, Min Suk; Lee, Jeongno; Kim, Won Keun; Wedel, Armin; Han, Chul Jong; Park, Sung Kyu

    2015-11-01

    The present work shows the effect of ethanolamine surface treatment on inverted InP quantum dot light-emitting diodes (QD-LEDs) with inorganic metal oxide layers. In the inverted structure of ITO/ZnO/InP QDs/CBP/MoO3/Al, a sol-gel derived ZnO film was used as an electron transport layer (ETL) and MoO3 was used as a hole injection layer (HIL). First, ethanolamine was treated as a surface modifier on top of the ZnO electron transport layer. The optical performance of the QD-LED device was improved by the ethanolamine surface treatment. Second, low temperature annealing (<200°C) was performed on the ZnO sol-gel electron transport layer, followed by an investigation of the effect of the ZnO annealing temperature. The efficiency of the inverted QD-LEDs was significantly enhanced (more than 3-fold) by optimization of the ZnO annealing temperature. [Figure not available: see fulltext.

  20. Towards a monolithically integrated III–V laser on silicon: optimization of multi-quantum well growth on InP on Si

    International Nuclear Information System (INIS)

    High-quality InGaAsP/InP multi-quantum wells (MQWs) on the isolated areas of indium phosphide on silicon necessary for realizing a monolithically integrated silicon laser is achieved. Indium phosphide layer on silicon, the pre-requisite for the growth of quantum wells is achieved via nano-epitaxial lateral overgrowth (NELOG) technique from a defective seed indium phosphide layer on silicon. This technique makes use of epitaxial lateral overgrowth (ELOG) from closely spaced (1 µm) e-beam lithography-patterned nano-sized openings (∼300 nm) by low-pressure hydride vapor phase epitaxy. A silicon dioxide mask with carefully designed opening patterns and thickness with respect to the opening width is used to block the defects propagating from the indium phosphide seed layer by the so-called necking effect. Growth conditions are optimized to obtain smooth surface morphology even after coalescence of laterally grown indium phosphide from adjacent openings. Surface morphology and optical properties of the NELOG indium phosphide layer are studied using atomic force microscopy, cathodoluminescence and room temperature µ-photoluminescence (µ-PL) measurements. Metal organic vapor phase epitaxial growth of InGaAsP/InP MQWs on the NELOG indium phosphide is conducted. The mask patterns to avoid loading effect that can cause excessive well/barrier thickness and composition change with respect to the targeted values is optimized. Cross-sectional transmission electron microscope studies show that the coalesced NELOG InP on Si is defect-free. PL measurement results indicate the good material quality of the grown MQWs. Microdisk (MD) cavities are fabricated from the MQWs on ELOG layer. PL spectra reveal the existence of resonant modes arising out of these MD cavities. A mode solver using finite difference method indicates the pertinent steps that should be adopted to realize lasing. (invited paper)

  1. Highly strained InAs quantum wells on InP substrates for mid-IR emission

    Science.gov (United States)

    Kim, Sangho; Kirch, Jeremy; Mawst, Luke

    2010-04-01

    Optical emission characteristics of indium arsenide (InAs) quantum wells were studied using organometallic vapor phase epitaxy (OMVPE). Low growth temperature (DQW) in a separate confinement hetero-structure (SCH) structure.

  2. When is an INP not an INP?

    Science.gov (United States)

    Simpson, Emma; Connolly, Paul; McFiggans, Gordon

    2016-04-01

    Processes such as precipitation and radiation depend on the concentration and size of different hydrometeors within clouds therefore it is important to accurately predict them in weather and climate models. A large fraction of clouds present in our atmosphere are mixed phase; contain both liquid and ice particles. The number of drops and ice crystals present in mixed phase clouds strongly depends on the size distribution of aerosols. Cloud condensation nuclei (CCN), a subset of atmospheric aerosol particles, are required for liquid drops to form in the atmosphere. These particles are ubiquitous in the atmosphere. To nucleate ice particles in mixed phase clouds ice nucleating particles (INP) are required. These particles are rarer than CCN. Here we investigate the case where CCN and INPs are in direct competition with each other for water vapour within a cloud. Focusing on the immersion and condensation modes of freezing (where an INP must be immersed within a liquid drop before it can freeze) we show that the presence of CCN can suppress the formation of ice. CCN are more hydrophilic than IN and as such are better able to compete for water vapour than, typically insoluble, INPs. Therefore water is more likely to condense onto a CCN than INP, leaving the INP without enough condensed water on it to be able to freeze in the immersion or condensation mode. The magnitude of this suppression effect strongly depends on a currently unconstrained quantity. Here we refer to this quantity as the critical mass of condensed water required for freezing, Mwc. Mwc is the threshold amount of water that must be condensed onto a INP before it can freeze in the immersion or condensation mode. Using the detailed cloud parcel model, Aerosol-Cloud-Precipiation-Interaction Model (ACPIM), developed at the University of Manchester we show that if only a small amount of water is required for freezing there is little suppression effect and if a large amount of water is required there is a

  3. Photoabsorption and resonance energy transfer phenomenon in CdTe-protein bioconjugates: an insight into QD-biomolecular interactions.

    Science.gov (United States)

    Vinayaka, Aaydha C; Thakur, Munna S

    2011-05-18

    Luminescent quantum dots (QDs) possess unique photophysical properties, which are advantageous in the development of new generation robust fluorescent probes based on Forster resonance energy transfer (FRET) phenomena. Bioconjugation of these QDs with biomolecules create hybrid materials having unique photophysical properties along with biological activity. The present study is aimed at characterizing QD bioconjugates in terms of optical behavior. Colloidal CdTe QDs capped with 3-mercaptopropionic acid (MPA) were conjugated to different proteins by the carbodiimide protocol using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and a coupling reagent like N-hydroxysuccinimide (NHS). The photoabsorption of these QD-protein bioconjugates demonstrated an effective coupling of electronic orbitals of constituents. A linear variation in absorbance of bioconjugates at 330 nm proportionate to conjugation suggests a covalent attachment as confirmed by gel electrophoresis. A red shift in the fluorescence of bovine serum albumin (BSA) due to conjugation inferred a decrease in Stokes shift and solvent polarization effects on protein. A proportionate quenching in BSA fluorescence followed by an enhancement of QD fluorescence point toward nonradiative dipolar interactions. Further, reduction in photobleaching of BSA suggests QD-biomolecular interactions. Bioconjugation has significantly influenced the photoabsorption spectrum of QD bioconjugates suggesting the formation of a possible protein shell on the surface of QD. The experimental result suggests that these bioconjugates can be considered nanoparticle (NP) superstructures for the development of a new generation of robust nanoprobes. PMID:21452896

  4. Droplet epitaxial growth of highly symmetric quantum dots emitting at telecommunication wavelengths on InP(111)A

    International Nuclear Information System (INIS)

    We demonstrate the formation of InAs quantum dots (QDs) on InAlAs/InP(111)A by means of droplet epitaxy. The C3v symmetry of the (111)A substrate enabled us to realize highly symmetric QDs that are free from lateral elongations. The QDs exhibit a disk-like truncated shape with an atomically flat top surface. Photoluminescence signals show broad-band spectra at telecommunication wavelengths of 1.3 and 1.5 μm. Strong luminescence signals are retained up to room temperature. Thus, our QDs are potentially useful for realizing an entangled photon-pair source that is compatible with current telecommunication fiber networks

  5. Composition-dependent trap distributions in CdSe and InP quantum dots probed using photoluminescence blinking dynamics

    Science.gov (United States)

    Chung, Heejae; Cho, Kyung-Sang; Koh, Weon-Kyu; Kim, Dongho; Kim, Jiwon

    2016-07-01

    Although Group II-VI quantum dots (QDs) have attracted much attention due to their wide range of applications in QD-based devices, the presence of toxic ions in II-VI QDs raises environmental concerns. To fulfill the demands of nontoxic QDs, synthetic routes for III-V QDs have been developed. However, only a few comparative analyses on optical properties of III-V QDs have been performed. In this study, the composition-related energetic trap distributions have been explored by using three different types of core/multishell QDs: CdSe-CdS (CdSe/CdS/ZnS), InP-ZnSe (InP/ZnSe/ZnS), and InP-GaP (InP/GaP/ZnS). It was shown that CdSe-CdS QDs have much larger trap densities than InP-shell QDs at higher energy states (at least 1Eg (band gap energy) above the lowest conduction band edge) based on probability density plots and Auger ionization efficiencies which are determined by analyses of photoluminescence blinking dynamics. This result suggests that the composition of encapsulated QDs is closely associated with the charge trapping processes, and also provides an insight into the development of more environmentally friendly QD-based devices.Although Group II-VI quantum dots (QDs) have attracted much attention due to their wide range of applications in QD-based devices, the presence of toxic ions in II-VI QDs raises environmental concerns. To fulfill the demands of nontoxic QDs, synthetic routes for III-V QDs have been developed. However, only a few comparative analyses on optical properties of III-V QDs have been performed. In this study, the composition-related energetic trap distributions have been explored by using three different types of core/multishell QDs: CdSe-CdS (CdSe/CdS/ZnS), InP-ZnSe (InP/ZnSe/ZnS), and InP-GaP (InP/GaP/ZnS). It was shown that CdSe-CdS QDs have much larger trap densities than InP-shell QDs at higher energy states (at least 1Eg (band gap energy) above the lowest conduction band edge) based on probability density plots and Auger ionization

  6. Cytotoxicity assessment of functionalized CdSe, CdTe and InP quantum dots in two human cancer cell models

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing [Institute of Gerontology and Geriatrics & Beijing Key Lab of Aging and Geriatrics, Chinese PLA General Hospital, Beijing 100853 (China); Hu, Rui [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, Jianwei [Institute of Gerontology and Geriatrics & Beijing Key Lab of Aging and Geriatrics, Chinese PLA General Hospital, Beijing 100853 (China); Zhang, Butian; Wang, Yucheng [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, Xin [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Law, Wing-Cheung [Department of Industrial and System Engineering, The Hang Kong Polytechnic University, Hung Hom (Hong Kong); Liu, Liwei [School of Science, Changchun University of Science and Technology, Changchun 130022 (China); Ye, Ling, E-mail: lye_301@163.com [Institute of Gerontology and Geriatrics & Beijing Key Lab of Aging and Geriatrics, Chinese PLA General Hospital, Beijing 100853 (China); Yong, Ken-Tye, E-mail: ktyong@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2015-12-01

    The toxicity of quantum dots (QDs) has been extensively studied over the past decade. Some common factors that originate the QD toxicity include releasing of heavy metal ions from degraded QDs and the generation of reactive oxygen species on the QD surface. In addition to these factors, we should also carefully examine other potential QD toxicity causes that will play crucial roles in impacting the overall biological system. In this contribution, we have performed cytotoxicity assessment of four types of QD formulations in two different human cancer cell models. The four types of QD formulations, namely, mercaptopropionic acid modified CdSe/CdS/ZnS QDs (CdSe-MPA), PEGylated phospholipid encapsulated CdSe/CdS/ZnS QDs (CdSe-Phos), PEGylated phospholipid encapsulated InP/ZnS QDs (InP-Phos) and Pluronic F127 encapsulated CdTe/ZnS QDs (CdTe-F127), are representatives for the commonly used QD formulations in biomedical applications. Both the core materials and the surface modifications have been taken into consideration as the key factors for the cytotoxicity assessment. Through side-by-side comparison and careful evaluations, we have found that the toxicity of QDs does not solely depend on a single factor in initiating the toxicity in biological system but rather it depends on a combination of elements from the particle formulations. More importantly, our toxicity assessment shows different cytotoxicity trend for all the prepared formulations tested on gastric adenocarcinoma (BGC-823) and neuroblastoma (SH-SY5Y) cell lines. We have further proposed that the cellular uptake of these nanocrystals plays an important role in determining the final faith of the toxicity impact of the formulation. The result here suggests that the toxicity of QDs is rather complex and it cannot be generalized under a few assumptions reported previously. We suggest that one have to evaluate the QD toxicity on a case to case basis and this indicates that standard procedures and comprehensive

  7. Cytotoxicity assessment of functionalized CdSe, CdTe and InP quantum dots in two human cancer cell models

    International Nuclear Information System (INIS)

    The toxicity of quantum dots (QDs) has been extensively studied over the past decade. Some common factors that originate the QD toxicity include releasing of heavy metal ions from degraded QDs and the generation of reactive oxygen species on the QD surface. In addition to these factors, we should also carefully examine other potential QD toxicity causes that will play crucial roles in impacting the overall biological system. In this contribution, we have performed cytotoxicity assessment of four types of QD formulations in two different human cancer cell models. The four types of QD formulations, namely, mercaptopropionic acid modified CdSe/CdS/ZnS QDs (CdSe-MPA), PEGylated phospholipid encapsulated CdSe/CdS/ZnS QDs (CdSe-Phos), PEGylated phospholipid encapsulated InP/ZnS QDs (InP-Phos) and Pluronic F127 encapsulated CdTe/ZnS QDs (CdTe-F127), are representatives for the commonly used QD formulations in biomedical applications. Both the core materials and the surface modifications have been taken into consideration as the key factors for the cytotoxicity assessment. Through side-by-side comparison and careful evaluations, we have found that the toxicity of QDs does not solely depend on a single factor in initiating the toxicity in biological system but rather it depends on a combination of elements from the particle formulations. More importantly, our toxicity assessment shows different cytotoxicity trend for all the prepared formulations tested on gastric adenocarcinoma (BGC-823) and neuroblastoma (SH-SY5Y) cell lines. We have further proposed that the cellular uptake of these nanocrystals plays an important role in determining the final faith of the toxicity impact of the formulation. The result here suggests that the toxicity of QDs is rather complex and it cannot be generalized under a few assumptions reported previously. We suggest that one have to evaluate the QD toxicity on a case to case basis and this indicates that standard procedures and comprehensive

  8. InAs quantum wire induced composition modulation in an In0.53Ga0.37Al0.10As barrier layer grown on an InP substrate

    International Nuclear Information System (INIS)

    Composition modulations are observed by transmission electron microscopy in In0.53Ga0.37Al0.10As barrier layers that overgrow both single- and multilayer InAs quantum wire structures grown on an InP substrate. Indium-rich (gallium-deficient) regions were observed in the region of the barrier layer lying directly above individual quantum wires, while indium-deficient (gallium-rich) regions were detected in the barrier above the gaps between adjacent underlying quantum wires. The magnitude of such modulation was typically 7% (atomic percent) for both indium and gallium as estimated from the energy dispersive x-ray analysis. The origin of such composition modulations was determined by modeling the chemical potential distribution for indium and gallium on the growth front of the barrier layer at the initial capping stage of the quantum wires with finite element simulations. It is found that the number and positions of the indium-rich regions are determined by the combined effects of strain and surface energy distributions on the barrier material capping the quantum wires. Moreover the estimated magnitudes of the composition modulation for both indium and gallium from the finite element models are in good agreement with the experimental observations. This method provides a simple way to understand the origin of, and to estimate the magnitude of the quantum wire-induced composition modulation in the barrier layer.

  9. Linkable thiocarbamoylbenzamidines as ligands for bioconjugation of Rhenium and Technetium

    International Nuclear Information System (INIS)

    Bioconjugation reactions with Rhenium and Technetium are of high importance for the development of novel radiopharmaceuticals for nuclear medicine. In this thesis the possibilities for bioconjugation using linkable Thiocarmbamoylbenzamidines as ligands for the complexation of Rhenium and Technetium were examined.

  10. Bioconjugation of antibodies to horseradish peroxidase (hrp)

    Science.gov (United States)

    The bioconjugation of an antibody to an enzymatic reporter such as horseradish peroxidase (HRP) affords an effective mechanism by which immunoassay detection of a target antigen can be achieved. The use of heterobifunctional cross—linkers to covalently link antibodies to HRP provides a simple and c...

  11. Organometallic palladium reagents for cysteine bioconjugation

    Science.gov (United States)

    Vinogradova, Ekaterina V.; Zhang, Chi; Spokoyny, Alexander M.; Pentelute, Bradley L.; Buchwald, Stephen L.

    2015-10-01

    Reactions based on transition metals have found wide use in organic synthesis, in particular for the functionalization of small molecules. However, there are very few reports of using transition-metal-based reactions to modify complex biomolecules, which is due to the need for stringent reaction conditions (for example, aqueous media, low temperature and mild pH) and the existence of multiple reactive functional groups found in biomolecules. Here we report that palladium(II) complexes can be used for efficient and highly selective cysteine conjugation (bioconjugation) reactions that are rapid and robust under a range of bio-compatible reaction conditions. The straightforward synthesis of the palladium reagents from diverse and easily accessible aryl halide and trifluoromethanesulfonate precursors makes the method highly practical, providing access to a large structural space for protein modification. The resulting aryl bioconjugates are stable towards acids, bases, oxidants and external thiol nucleophiles. The broad utility of the bioconjugation platform was further corroborated by the synthesis of new classes of stapled peptides and antibody-drug conjugates. These palladium complexes show potential as benchtop reagents for diverse bioconjugation applications.

  12. Quantum Dots for Biophotonics

    OpenAIRE

    Ken-Tye Yong

    2012-01-01

    This theme issue provides an excellent collection of reviews and original research articles on the study of various bioconjugated quantum dot formulations for diagnostics and therapy applications using biophotonic imaging and sensing approaches.

  13. Bioconjugation and stabilisation of biomolecules in biosensors.

    Science.gov (United States)

    Liébana, Susana; Drago, Guido A

    2016-06-30

    Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein-polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies. PMID:27365036

  14. Structural and electrical properties of quantum wells with nanoscale InAs inserts in InyAl1−yAs/InxGa1−xAs heterostructures on InP substrates

    International Nuclear Information System (INIS)

    A complex study of the effect ofintroduction of nanoscale InAs inserts of different thicknesses into an In0.53Ga0.47As quantum well on the electrical properties and structural features of In0.50Al0.50As/In0.53Ga0.47As/In0.50Al0.50As nanoheterostructures with bilateral δ-Si doping grown on InP substrates has been performed. The layers of nanoheterostructures with a weak lattice mismatch are found to be equally (cube-on-cube) oriented. The introduction of a nanoscale InAs insert leads to an increase in mobility. At an insert thickness of about 1.8 nm, the effect of increasing mobility is saturated due to structural deterioration. The segregation of the second (apparently, wurtzite) phase is revealed; this process, as well as the formation of other defects in the nanoheterostructure layers, is due to local strains caused by variations of the indium content in the layers.

  15. Electronic structure, morphology and emission polarization of enhanced symmetry InAs quantum-dot-like structures grown on InP substrates by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Maryński, A.; Sĕk, G.; Musiał, A.; Andrzejewski, J.; Misiewicz, J. [Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland); Gilfert, C.; Reithmaier, J. P. [Technische Physik, Institute of Nanostructure Technology and Analytics, CINSaT, University of Kassel, Heinrich Plett-Str. 40, D-34132 Kassel (Germany); Capua, A.; Karni, O.; Gready, D.; Eisenstein, G. [Department of Electrical Engineering, Technion, Haifa 32000 (Israel); Atiya, G.; Kaplan, W. D. [Department of Materials Science and Engineering, Technion, Haifa 32000 (Israel); Kölling, S. [Fraunhofer Institute for Photonic Microsystems, Center for Nanoelectronic Technologies, Königsbrücker Straße 180, D-01099 Dresden (Germany)

    2013-09-07

    The optical and structural properties of a new kind of InAs/InGaAlAs/InP quantum dot (QD)-like objects grown by molecular beam epitaxy have been investigated. These nanostructures were found to have significantly more symmetrical shapes compared to the commonly obtained dash-like geometries typical of this material system. The enhanced symmetry has been achieved due to the use of an As{sub 2} source and the consequent shorter migration length of the indium atoms. Structural studies based on a combination of scanning transmission electron microscopy (STEM) and atom probe tomography (APT) provided detailed information on both the structure and composition distribution within an individual nanostructure. However, it was not possible to determine the lateral aspect ratio from STEM or APT. To verify the in-plane geometry, electronic structure calculations, including the energy levels and transition oscillator strength for the QDs have been performed using an eight-band k·p model and realistic system parameters. The results of calculations were compared to measured polarization-resolved photoluminescence data. On the basis of measured degree of linear polarization of the surface emission, the in-plane shape of the QDs has been assessed proving a substantial increase in lateral symmetry. This results in quantum-dot rather than quantum-dash like properties, consistent with expectations based on the growth conditions and the structural data.

  16. Influence of poly(vinyl alcohol) degree of hydrolysis in the production of quantum dots for bioconjugation; Influencia do grau de hidrolise do poli(alcool vinilico) na obtencao de pontos quanticos para bioconjugacao

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Quantum dots, also known as semiconducting nanoparticle, are promising zero-dimensional advanced materials because of their nanoscale size and their quantum confinement properties. One of the fastest moving and most exciting interfaces of nanotechnology is the use of QDs in medicine, cell, and molecular biology, especially as biological detectors. In the case of these applications, it is crucial QDs synthesis based on aqueous routes and biocompatible stabilizers. In this sense, the main goal of this study was to obtain cadmium sulfide quantum dots from aqueous route using poly(vinyl alcohol), PVA, as capping agent, evaluating the influence of polymer degree of hydrolysis in nanoparticle formation and stabilization. UV-Vis spectroscopy was used to detect quantum dots production and size. The results have shown that PVA degree of hydrolysis is a crucial parameter to be controlled in order to obtain semiconducting nanoparticles in aqueous media for conjugation with biomolecules such as immunoglobulins, proteins, DNS, and oligonucleotides. (author)

  17. Staudinger ligation as a method for bioconjugation.

    Science.gov (United States)

    van Berkel, Sander S; van Eldijk, Mark B; van Hest, Jan C M

    2011-09-12

    In 1919 the German chemist Hermann Staudinger was the first to describe the reaction between an azide and a phosphine. It was not until recently, however, that Bertozzi and co-workers recognized the potential of this reaction as a method for bioconjugation and transformed it into the so-called Staudinger ligation. The bio-orthogonal character of both the azide and the phosphine functions has resulted in the Staudinger ligation finding numerous applications in various complex biological systems. For example, the Staudinger ligation has been utilized to label glycans, lipids, DNA, and proteins. Moreover, the Staudinger ligation has been used as a synthetic method to construct glycopeptides, microarrays, and functional biopolymers. In the emerging field of bio-orthogonal ligation strategies, the Staudinger ligation has set a high standard to which most of the new techniques are often compared. This Review summarizes recent developments and new applications of the Staudinger ligation. PMID:21887733

  18. Colloidal InP nanocrystal

    International Nuclear Information System (INIS)

    Full text: InP nanodots with the diameter of 4-10 nm were synthesized using sol-gel method. The nanodot dimensions were obtained using TEM, and we found the d(111) spacing to be 0.328nm which agrees within 3% of the literature value. Prepared nanoparticles where characterized then by Raman spectroscopy and X-ray diffraction. Performed measurements confirm good crystalline quality of obtained InP particles, which can be used as a basis for THz emitters, LED, and OLED displays. The synthesis of InP semiconductor nanodots was performed in a round-bottom three-neck flask equipped with a magnetic stirrer and heater with temperature control unit. The Na3P was obtained as a result of reaction of sodium and white phosphorous (similar as for GaP nanodots). The reaction mixture turned dark during synthesis due to the formation of Na3P suspension. The subsequent synthesis of indium phosphide nanodots was carried out by rapid injection of a suspension of sodium phosphide, maintained at room-temperature into a high stirred solution of indium chloride heated 150 degrees Celsius under N2 atmosphere. InCl3 + Na3P → InP + 3NaCl. The reaction mixture was then maintained at the fixed temperature for 2 h and then promptly cooled to room temperature using an ice-water bath. A solution containing 50% of ethanol and 50% of distilled water was used to dissolve the sodium chloride precipitated at the same time with the InP nanoparticles.

  19. Characterization of Multienzyme-Antibody-Carbon Nanotube Bioconjugates for Immunosensors

    OpenAIRE

    Jensen, Gary C.; Yu, Xin; Gong, Joseph D.; Munge, Bernard; Bhirde, Ashwin; Kim, Sang N.; Papadimitrakopoulos, Fotios; Rusling, James F.

    2009-01-01

    Characterization studies of a multi-enzyme-antibody-carbon nanotube bioconjugate designed for the amplification of electrochemical immunosensing are described. Secondary antibodies for prostate specific antigen (PSA) were covalently linked to highly carboxylated multi-walled carbon nanotube (CNT) along with multiple horseradish peroxidase (HRP) enzyme labels. These bioconjugates provide ultra-sensitive amperometric detection of PSA on a single-wall carbon nanotube forest sandwich immunosensor...

  20. Fabrication and complete characterization of polarization insensitive 1310 nm InGaAsP InP quantum-well semiconductor optical amplifiers

    Science.gov (United States)

    Jin, Jinyan; Tian, Decheng; Shi, Jing; Li, Tongning

    2004-01-01

    Polarization insensitive 1310 nm InGaAsP-InP multi-quantum-well (MQW) semiconductor optical amplifiers (SOAs), with 7° tilted ridge waveguide and buried-window end facets, have been fabricated and fully characterized on chip and module level. SOAs chips with an optimized complex strained MQW active region exhibited less than 1 dB polarization dependence of amplified spontaneous power in the drive current range of 50-200 mA. The amplifier module, having a residual facet reflectivity of 2.8 × 10-5, achieved 25 dB fibre-to-fibre unsaturated gain, for both transverse electric and transverse magnetic polarization states, 11.2 dBm saturation output power, and 7.6 dB noise figure at 1310 nm. The polarization dependence of gain was less than 0.6 dB in the 3 dB gain bandwidth of 56 nm. Coupling efficiency played a significant role in the gain, saturation output power and noise figure of a SOA module. Spot-size-converter integrated SOAs with buried heterostructures are expected to exhibit further improved performances.

  1. CNPq/INPE-LANDSAT system

    Science.gov (United States)

    Debarrosaguirre, J. L.

    1985-01-01

    The current status of the Brazilian LANDSAT facilities operated by Instituto de Pesquisas Espaciais (INPE) and the results achieved during the period from October 1, 1984 to August 31, 1985 are presented. INPE's Receiving Station at Cuiaba, MT, operates normally the two tracking and receiving systems it has installed, the old one (1973) for Band S and the new one (February 1983) for dual S- and X-band. Both MSS and TM recording capabilities are functional. Support to the NASA Backup Plan for MSS data also remains active. Routine recordings are being made for LANDSAT-5 only, for both MSS and TM. Originally, MSS was recorded over the full acquisition range. However, since December, 1984, due to further reduction of operational expenses, both instruments are being recorded over Brazilian territory only.

  2. 8-band and 14-band kp modeling of electronic band structure and material gain in Ga(In)AsBi quantum wells grown on GaAs and InP substrates

    International Nuclear Information System (INIS)

    The electronic band structure and material gain have been calculated for GaAsBi/GaAs quantum wells (QWs) with various bismuth concentrations (Bi ≤ 15%) within the 8-band and 14-band kp models. The 14-band kp model was obtained by extending the standard 8-band kp Hamiltonian by the valence band anticrossing (VBAC) Hamiltonian, which is widely used to describe Bi-related changes in the electronic band structure of dilute bismides. It has been shown that in the range of low carrier concentrations n < 5 × 1018 cm−3, material gain spectra calculated within 8- and 14-band kp Hamiltonians are similar. It means that the 8-band kp model can be used to calculate material gain in dilute bismides QWs. Therefore, it can be applied to analyze QWs containing new dilute bismides for which the VBAC parameters are unknown. Thus, the energy gap and electron effective mass for Bi-containing materials are used instead of VBAC parameters. The electronic band structure and material gain have been calculated for 8 nm wide GaInAsBi QWs on GaAs and InP substrates with various compositions. In these QWs, Bi concentration was varied from 0% to 5% and indium concentration was tuned in order to keep the same compressive strain (ε = 2%) in QW region. For GaInAsBi/GaAs QW with 5% Bi, gain peak was determined to be at about 1.5 μm. It means that it can be possible to achieve emission at telecommunication windows (i.e., 1.3 μm and 1.55 μm) for GaAs-based lasers containing GaInAsBi/GaAs QWs. For GaInAsBi/Ga0.47In0.53As/InP QWs with 5% Bi, gain peak is predicted to be at about 4.0 μm, i.e., at the wavelengths that are not available in current InP-based lasers

  3. Photoconductivity relaxation in nanostructured InP

    International Nuclear Information System (INIS)

    We show that long-duration-photoconductivity decay (LDPCD) and persistent photoconductivity (PPC) in porous InP structures produced by anodization of InP substrates can be controlled through the control of their morphology. Particularly, the PPC inherent at low temperatures to porous InP layers with the thickness of skeleton walls comparable with pore diameters is quenched in structures consisting of ultrathin walls produced at high anodization voltages. (authors)

  4. Bioconjugation of oligonucleotides for treating liver fibrosis.

    Science.gov (United States)

    Ye, Zhaoyang; Houssein, Houssam S Hajj; Mahato, Ram I

    2007-01-01

    Liver fibrosis results from chronic liver injury due to hepatitis B and C, excessive alcohol ingestion, and metal ion overload. Fibrosis culminates in cirrhosis and results in liver failure. Therefore, a potent antifibrotic therapy is urgently needed to reverse scarring and eliminate progression to cirrhosis. Although activated hepatic stellate cells (HSCs) remain the principle cell type responsible for liver fibrosis, perivascular fibroblasts of portal and central veins as well as periductular fibroblasts are other sources of fibrogenic cells. This review will critically discuss various treatment strategies for liver fibrosis, including prevention of liver injury, reduction of inflammation, inhibition of HSC activation, degradation of scar matrix, and inhibition of aberrant collagen synthesis. Oligonucleotides (ODNs) are short, single-stranded nucleic acids, which disrupt expression of target protein by binding to complementary mRNA or forming triplex with genomic DNA. Triplex forming oligonucleotides (TFOs) provide an attractive strategy for treating liver fibrosis. A series of TFOs have been developed for inhibiting the transcription of alpha1(I) collagen gene, which opens a new area for antifibrotic drugs. There will be in-depth discussion on the use of TFOs and how different bioconjugation strategies can be utilized for their site-specific delivery to HSCs or hepatocytes for enhanced antifibrotic activities. Various insights developed in individual strategy and the need for multipronged approaches will also be discussed. PMID:18154454

  5. Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry.

    Science.gov (United States)

    Mason, Alexander F; Thordarson, Pall

    2016-01-01

    The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation. We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers. PMID:27501061

  6. InP based lasers and optical amplifiers with wire-/dot-like active regions

    DEFF Research Database (Denmark)

    Reithmaier, J. P.; Somers, A.; Deubert, S.; Schwertberger, R.; Kaiser, W.; Forchel, A.; Calligaro, M.; Resneau, P.; Parillaud, O.; Bansropun, S.; Krakowski, M.; Alizon, R.; Hadass, D.; Bilenca, A.; Dery, H.; Mikhelashvili, V.; Eisenstein, G.; Gioannini, M.; Montrosset, I.; Berg, Tommy Winther; Poel, Mike van der; Mørk, Jesper; Tromborg, Bjarne

    2005-01-01

    Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 - 1.65 mm. In a brief overview different technological approaches will be ...

  7. Optical trends in InP polytypic superlattices

    Science.gov (United States)

    Sipahi, Guilherme; de Campos, Tiago; de Faria Junior, Paulo Eduardo

    2015-03-01

    Recent advances in growth techniques have allowed the fabrication of semiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases. Although the optical characterization of these polytypic structures is well reported in the literature, a deeper theoretical understanding of how crystal phase mixing and quantum confinement change the output linear light polarization is still needed. Here, we theoretically investigate the effects of these polytypic homojunctions on the interband absorption of an InP superlattice. Using a single 8x8 k.p Hamiltonian that describes both crystal phases together with the effects of quantum and optical confinement we where able to explain the recent optical exeperimental results carried on polytypic InP. In summary, we have shown how the interplay of crystal phase mixing and quantum confinement can be used for light polarization engineering in polytypic homojunctions. FAPESP (No. 2011/19333-4, No. 2012/05618-0 and No. 2013/23393-8) and CNPq (No. 138457/2011-5, No. 246549/2012-2 and No. 149904/2013-4)

  8. Design and fabrication of InP micro-ring resonant detectors

    Institute of Scientific and Technical Information of China (English)

    辛海明; 黄永清; 陈海波; 黄辉; 任晓敏; 周星光

    2009-01-01

    The quantum efficiency and the transient response of the InP semiconductor micro-ring resonant detector are analyzed to get the optimum design parameters.Then the side coupling micro-ring resonant is fabricated using the InP semiconductor material based on the parameters.The micro-ring resonant cavity has the raius of 80 μm,waveguide width of 3 μm and the coupler gap of 1 μm.The test results show that the FSR is 0.75 nm,and the FWHM is 0.5 nm,which are consistent with the theoretical calculation results.

  9. Photoluminescence study of as-grown vertically standing wurtzite InP nanowire ensembles

    International Nuclear Information System (INIS)

    We demonstrate a method that enables the study of photoluminescence of as-grown nanowires on a native substrate by non-destructively suppressing the contribution of substrate photoluminescence. This is achieved by using polarized photo-excitation and photoluminescence and by making an appropriate choice of incident angle of both excitation beam and photoluminescence collection direction. Using TE-polarized excitation at a wavelength of 488 nm at an incident angle of ∼70° we suppress the InP substrate photoluminescence relative to that of the InP nanowires by about 80 times. Consequently, the photoluminescence originating from the nanowires becomes comparable to and easily distinguishable from the substrate photoluminescence. The measured photoluminescence, which peaks at photon energies of ∼1.35 eV and ∼1.49 eV, corresponds to the InP substrate with zinc-blende crystal structure and to the InP nanowires with wurtzite crystal structure, respectively. The photoluminescence quantum yield of the nanowires was found to be ∼20 times lower than that of the InP substrate. The nanowires, grown vertically in a random ensemble, neither exhibit substantial emission polarization selectivity to the axis of the nanowires nor follow excitation polarization preferences observed previously for a single nanowire. (paper)

  10. Recyclable thermoresponsive polymer-cellulase bioconjugates for biomass depolymerization.

    Science.gov (United States)

    Mackenzie, Katherine J; Francis, Matthew B

    2013-01-01

    Here we report the construction and characterization of a recoverable, thermoresponsive polymer-endoglucanase bioconjugate that matches the activity of unmodified enzymes on insoluble cellulose substrates. Two copolymers exhibiting a thermoresponsive lower critical solution temperature (LCST) were created through the copolymerization of an aminooxy-bearing methacrylamide with N-isopropylacrylamide (NIPAm) or N-isopropylmethacrylamide (NIPMa). The aminooxy group provided a handle through which the LCST was adjusted through small-molecule quenching. This allowed materials with LCSTs ranging from 20.9 to 60.5 °C to be readily obtained after polymerization. The thermostable endoglucanase EGPh from the hypothermophilic Pyrococcus horikoshii was transaminated with pyridoxal-5'-phosphate to produce a ketone-bearing protein, which was then site-selectively modified through oxime linkage with benzylalkoxyamine or 5 kDa-poly(ethylene glycol)-alkoxyamine. These modified proteins showed activity comparable to the controls when assayed on an insoluble cellulosic substrate. Two polymer bioconjugates were then constructed using transaminated EGPh and the aminooxy-bearing copolymers. After 12 h, both bioconjugates produced an equivalent amount of free reducing sugars as the unmodified control using insoluble cellulose as a substrate. The recycling ability of the NIPAm copolymer-EGPh conjugate was determined through three rounds of activity, maintaining over 60% activity after two cycles of reuse and affording significantly more soluble carbohydrates than unmodified enzyme alone. When assayed on acid-pretreated Miscanthus, this bioconjugate increased the amount of reducing sugars by 2.8-fold over three rounds of activity. The synthetic strategy of this bioconjugate allows the LCST of the material to be changed readily from a common stock of copolymer and the method of attachment is applicable to a variety of proteins, enabling the same approach to be amenable to thermophile

  11. Synthesis of Bioconjugate Sesterterpenoids with Phospholipids and Polyunsaturated Fatty Acids.

    Science.gov (United States)

    Gil-Mesón, Ana; Roncero, Alejandro M; Tobal, Ignacio E; Basabe, Pilar; Díez, David; Mollinedo, Faustino; Marcos, Isidro S

    2015-01-01

    A series of sesterterpenoid bioconjugates with phospholipids and polyunsaturated fatty acids (PUFAs) have been synthesized for biological activity testing as antiproliferative agents in several cancer cell lines. Different substitution analogues of the original lipidic ether edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) are obtained varying the sesterterpenoid in position 1 or 2 of the glycerol or a phosphocholine or PUFA unit in position 3. Simple bioconjugates of sesterterpenoids and eicosapentaenoic acid (EPA) have been obtained too. All synthetic derivatives were tested against the human tumour cell lines HeLa (cervix) and MCF-7 (breast). Some compounds showed good IC50 (0.3 and 0.2 μM) values against these cell lines. PMID:26729084

  12. Synthesis of Bioconjugate Sesterterpenoids with Phospholipids and Polyunsaturated Fatty Acids

    Directory of Open Access Journals (Sweden)

    Ana Gil-Mesón

    2015-12-01

    Full Text Available A series of sesterterpenoid bioconjugates with phospholipids and polyunsaturated fatty acids (PUFAs have been synthesized for biological activity testing as antiproliferative agents in several cancer cell lines. Different substitution analogues of the original lipidic ether edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine are obtained varying the sesterterpenoid in position 1 or 2 of the glycerol or a phosphocholine or PUFA unit in position 3. Simple bioconjugates of sesterterpenoids and eicosapentaenoic acid (EPA have been obtained too. All synthetic derivatives were tested against the human tumour cell lines HeLa (cervix and MCF-7 (breast. Some compounds showed good IC50 (0.3 and 0.2 μM values against these cell lines.

  13. Recyclable Thermoresponsive Polymer-Cellulase Bioconjugates for Biomass Depolymerization

    OpenAIRE

    Mackenzie, Katherine J.; Francis, Matthew B.

    2012-01-01

    Here we report the construction and characterization of a recoverable, thermoresponsive polymer-endoglucanase bioconjugate that matches the activity of unmodified enzymes on insoluble cellulose substrates. Two copolymers exhibiting a thermoresponsive lower critical solution temperature (LCST) were created through the copolymerization of an aminooxy-bearing methacrylamide with N-isopropylacrylamide (NIPAm) or N-isopropylmethacrylamide (NIPMa). The aminooxy group provided a handle through which...

  14. Bio-Conjugated Polycaprolactone Membranes: A Novel Wound Dressing

    OpenAIRE

    Cai, Elijah Zhengyang; Teo, Erin Yiling; Jing, Lim; Koh, Yun Pei; Qian, Tan Si; Wen, Feng; Lee, James Wai Kit; Hing, Eileen Chor Hoong; Yap, Yan Lin; Lee, Hanjing; Lee, Chuen Neng; Teoh, Swee-Hin; Lim,Jane; Lim, Thiam Chye

    2014-01-01

    Background The combination of polycaprolactone and hyaluronic acid creates an ideal environment for wound healing. Hyaluronic acid maintains a moist wound environment and accelerates the in-growth of granulation tissue. Polycaprolactone has excellent mechanical strength, limits inflammation and is biocompatible. This study evaluates the safety and efficacy of bio-conjugated polycaprolactone membranes (BPM) as a wound dressing. Methods 16 New Zealand white rabbits were sedated and local anaest...

  15. Segregation of antimony in InP in MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Weeke, Stefan

    2008-07-01

    In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

  16. Transition metal bioconjugates with an organometallic link between the metal and the biomolecular scaffold

    OpenAIRE

    Monney, Angèle; Albrecht, Martin

    2013-01-01

    This overview compiles recent advances in the synthesis and application of organometallic bioconjugates that comprise a metal–carbon linkage between the metal and the biomolecular scaffold. This specific area of bioorganometallic chemistry has been spurred by the discovery of naturally occurring bioorganometallic compounds and afforded organometallic bioconjugates from transition metals binding to amino acids, nucleic acids and other biomolecules. These artificial bioorganometallic compounds ...

  17. InP based lasers and optical amplifiers with wire-/dot-like active regions

    International Nuclear Information System (INIS)

    Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire-/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 and 1.65 μm. In a brief overview different technological approaches will be discussed, while in the main part the current status and recent results of quantum-dash lasers are reported. This includes topics like dash formation and material growth, device performance of lasers and optical amplifiers, static and dynamic properties and fundamental material and device modelling

  18. Application of Quantum-Dot Conjugates for Detection and Subspecies Differentiation of Vibrio cholerae by Optical Methods

    Science.gov (United States)

    Erohin, P. S.; Utkin, D. V.; Kouklev, V. E.; Ossina, N. A.; Miheeva, E. A.; Alenkina, T. V.

    2016-03-01

    The application of bioconjugates of specific antibodies and CdSe quantum dots to identify two serovariants of Vibrio cholerae using fluorescence microscopy and optical spectroscopy is considered. It is found that a mixture of different bioconjugates with different emission maxima can be used without affecting the specificity of the method. Different V. cholerae serovariants are colored differently in fl uorescence microscopy (bright green and bright yellow), thereby allowing subspecies differentiation. The absorption spectrum of the bacterial suspension changed with homologous antigens in the sample and did not change with heterologous antigens. It is shown that the quantum-dot bioconjugates can serve as an alternative to the traditional fluorescence and agglutination diagnostics.

  19. Unusual nanostructures of “lattice matched” InP on AlInAs

    International Nuclear Information System (INIS)

    We show that the morphology of the initial monolayers of InP on Al0.48In0.52As grown by metalorganic vapor-phase epitaxy does not follow the expected layer-by-layer growth mode of lattice-matched systems, but instead develops a number of low-dimensional structures, e.g., quantum dots and wires. We discuss how the macroscopically strain-free heteroepitaxy might be strongly affected by local phase separation/alloying-induced strain and that the preferred aggregation of adatom species on the substrate surface and reduced wettability of InP on AlInAs surfaces might be the cause of the unusual (step) organization and morphology

  20. Thermal diffusion in nanostructured porous InP

    Indian Academy of Sciences (India)

    R Srinivasan; K Ramachandran

    2008-11-01

    Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL. Thermal properties studied by photoacoustic (PA) spectroscopy revealed one order decrease in thermal conductivity of porous InP compared to the bulk. Further it is shown that the thermal conductivity of porous InP decreases with decrease in size of the particles.

  1. Enhanced bandgap blue-shift due to group V intermixing in InGaAsP multiple quantum well laser structures induced by low temperature grown InP

    Czech Academy of Sciences Publication Activity Database

    Lee, A. S. W.; MacKenzie, M.; Thompson, D. A.; Buršík, Jiří; Robinson, B. J.; Weatherly, G. C.

    2001-01-01

    Roč. 78, č. 21 (2001), s. 3199-3201. ISSN 0003-6951 Institutional research plan: CEZ:AV0Z2041904 Keywords : quantum well * band-gap * intermixing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.849, year: 2001

  2. Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles

    DEFF Research Database (Denmark)

    León, John Jairo Castillo; Bertel, Linda; Páez-Mozo, Edgar;

    2013-01-01

    In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic...... at 4°C prolongs the stability of folic acid-gold nanoparticle suspensions to up to 26 days. Ultraviolet visible and Fourier transform infrared spectroscopy showed a surface plasmon band of around 534nm and fluorescence spectroscopy exhibited a quenching effect on gold nanoparticles in the...... fluorescence emission of folic acid and thus confirmed the conjugation of folic acid to the surface of gold nanoparticles. In this study we demonstrate the use of a photochemistry method to obtain folic acid-gold nanoparticles in a simple and rapid way without the use of surfactants and long reaction times...

  3. Biodistribution imaging of a paclitaxel-hyaluronan bioconjugate

    Energy Technology Data Exchange (ETDEWEB)

    Banzato, Alessandra; Rondina, Maria [Department of Oncology and Surgical Sciences, University of Padua, I-35128 Padova (Italy); Melendez-Alafort, Laura; Zangoni, Elena; Nadali, Anna [Department of Pharmaceutical Sciences, University of Padua, Padova (Italy); Renier, Davide [Fidia Farmaceutici, Abano Terme (Italy); Moschini, Giuliano [Department of Physics, University of Padua, Padova (Italy); Mazzi, Ulderico [Department of Pharmaceutical Sciences, University of Padua, Padova (Italy); Zanovello, Paola [Department of Oncology and Surgical Sciences, University of Padua, I-35128 Padova (Italy); Istituto Oncologico Veneto, IOV-IRCCS, Padova (Italy); Rosato, Antonio [Department of Oncology and Surgical Sciences, University of Padua, I-35128 Padova (Italy); Istituto Oncologico Veneto, IOV-IRCCS, Padova (Italy)], E-mail: antonio.rosato@unipd.it

    2009-07-15

    Introduction: Gamma-ray detectors represent sensitive and noninvasive instruments to evaluate in vivo the metabolic trapping of radiopharmaceuticals. This study aimed to assess the imaging biodistribution of a [{sup 99m}Tc]-radiolabelled new prototype bioconjugate composed of paclitaxel linked to hyaluronan (ONCOFID-P). Methods: A small gamma camera providing high-resolution images was employed. Imaging of biodistribution following intravenous, intraperitoneal, intravesical and oral administration was carried out for a 2-h period in anesthetized mice receiving [{sup 99m}Tc]ONCOFID-P. At the end of the observation time, radioactivity in organs was directly measured. As a control, groups of mice were treated with free [{sup 3}H]paclitaxel given according to the same administration routes, and organ biodistribution of the drug was assessed after 2 h. Results: Intravenous inoculation of [{sup 99m}Tc]ONCOFID-P was followed by a rapid and strong liver uptake. In fact, almost 80% of the imaging signal was detected in this organ 10 min after injection and such value remained constant thereafter, thus indicating that the bioconjugate given through the intravenous route could be well suited to targeting primary or metastatic liver neoplasias. Imaging of the bladder, abdomen and gastrointestinal tract after local administration disclosed that the radiolabelled compound remained confined to the cavities, suggesting a potential regional application for transitional bladder cell carcinomas, ovarian cancers and gastric tumors, respectively. Free [{sup 3}H]paclitaxel biodistribution profoundly differed from that of [{sup 99m}Tc]ONCOFID-P. Conclusions: Conjugation of drugs with polymers results in new chemical entities characterized by a modified biodistribution pattern. Therefore, preclinical studies based on imaging analysis of such new compounds can suggest novel therapeutic applications.

  4. Optimal activation of carboxyl-superparamagnetic iron oxide nanoparticles bioconjugated with antibody using orthogonal array design.

    Science.gov (United States)

    Liu, Lin; Zhang, Xiaoqang; Zhang, Yu; Pu, Yuepu; Yin, Lihong; Tang, Meng; Liu, Hui

    2013-12-01

    This study aims to bioconjugate anti-EMMPRIN monoclonal antibody on the surface of carboxyl-SPIO nanoparticles and to optimize the activated conditions of bioconjugation. Anti-EMMPRIN monoclonal antibody bioconjugated carboxyl-SPIO nanoparticles were performed through a coupling strategy of EDC and sulfo-NHS. The procedure was comprised of two steps by activation of carboxyl-SPIO nanoparticles and conjugation with monoclonal antibody. The optimal activated parameters of bioconjugation were evaluated by single factor design and orthogonal array design. SDS-PAGE analysis and Bradford assay was used for testing and verifying the efficiency of activated conditions obtained from orthogonal array. The results show that pH value, temperature and reaction time were important factors that influence bioconjugated efficiency. The activated parameters with pH value 6.2, temperature 25 degrees C and reaction time 30 min were obviously optimal for activation of carboxyl-SPIO nanoparticles and conjugation with monoclonal EMMPEIN antibody. This coupling strategy for anti-EMMPRIN mAb bioconjugated on SPIO nanoparticles was efficient, and may be further applied in the fields of medical or biological practices. PMID:24266206

  5. Bioconjugates of PAMAM dendrimers with trans-retinal, pyridoxal, and pyridoxal phosphate

    Directory of Open Access Journals (Sweden)

    Filipowicz A

    2012-09-01

    Full Text Available A Filipowicz, S WołowiecDepartment of Cosmetology, University of Information Technology and Management in Rzeszów, Rzeszów, PolandBackground: Bioconjugates of a polyamidoamine (PAMAM G3 dendrimer and an aldehyde were synthesized as carriers for vitamins A and B6, and the bioavailability of these vitamins for skin nutrition was investigated.Methods: Nuclear magnetic resonance (NMR and ultraviolet-visible methods were used to characterize the structure of the bioconjugates and for monitoring release of pyridoxal (Pyr and pyridoxal phosphate (PLP from these bioconjugates in vitro. A skin model permeation of bioconjugates was also studied in a Franz chamber.Results: A transdermal G3 PAMAM dendrimer was used to synthesize bioconjugates with trans-retinal (Ret, pyridoxal (Pyr, or PLP. These nanomolecules, containing up to four covalently linked Ret, Pyr, or PLP (G34Ret, G34Pyr, and G34PLP, were able to permeate the skin, as demonstrated in vitro using a model skin membrane. PLP and Pyr bound to a macromolecular vehicle were active cofactors for glutamic pyruvic transaminase, as shown by 1H NMR spectral monitoring of the progress of the L-alanine + α-ketoglutarate → glutamic acid + pyruvic acid reaction.Conclusion: PAMAM-PLP, PAMAM-Pyr, and PAMAM-Ret bioconjugates are able to permeate the skin. PLP and Pyr are available as cofactors for glutamic pyruvic transaminase.Keywords: PAMAM, trans-retinal, pyridoxal phosphate, pyridoxal, transamination

  6. Bandgap Engineering of InP QDs Through Shell Thickness and Composition

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, Allison M. [Los Alamos National Laboratory; Mangum, Benjamin D. [Los Alamos National Laboratory; Piryatinski, Andrei [Los Alamos National Laboratory; Park, Young-Shin [Los Alamos National Laboratory; Htoon, Han [Los Alamos National Laboratory; Hollingsworth, Jennifer A. [Los Alamos National Laboratory

    2012-06-21

    Fields as diverse as biological imaging and telecommunications utilize the unique photophysical and electronic properties of nanocrystal quantum dots (NQDs). The development of new NQD compositions promises material properties optimized for specific applications, while addressing material toxicity. Indium phosphide (InP) offers a 'green' alternative to the traditional cadmium-based NQDs, but suffers from extreme susceptibility to oxidation. Coating InP cores with more stable shell materials significantly improves nanocrystal resistance to oxidation and photostability. We have investigated several new InP-based core-shell compositions, correlating our results with theoretical predictions of their optical and electronic properties. Specifically, we can tailor the InP core-shell QDs to a type-I, quasi-type-II, or type-II bandgap structure with emission wavelengths ranging from 500-1300 nm depending on the shell material used (ZnS, ZnSe, CdS, or CdSe) and the thickness of the shell. Single molecule microscopy assessments of photobleaching and blinking are used to correlate NQD properties with shell thickness.

  7. 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.)

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

    International Nuclear Information System (INIS)

    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.)

  9. Analytical bioconjugates, aptamers, enable specific quantitative detection of Listeria monocytogenes.

    Science.gov (United States)

    Lee, Sang-Hee; Ahn, Ji-Young; Lee, Kyeong-Ah; Um, Hyun-Ju; Sekhon, Simranjeet Singh; Sun Park, Tae; Min, Jiho; Kim, Yang-Hoon

    2015-06-15

    As a major human pathogen in the Listeria genus, Listeria monocytogenes causes the bacterial disease listeriosis, which is a serious infection caused by eating food contaminated with the bacteria. We have developed an aptamer-based sandwich assay (ABSA) platform that demonstrates a promising potential for use in pathogen detection using aptamers as analytical bioconjugates. The whole-bacteria SELEX (WB-SELEX) strategy was adopted to generate aptamers with high affinity and specificity against live L. monocytogenes. Of the 35 aptamer candidates tested, LMCA2 and LMCA26 reacted to L. monocytogenes with high binding, and were consequently chosen as sensing probes. The ABSA platform can significantly enhance the sensitivity by employing a very specific aptamer pair for the sandwich complex. The ABSA platform exhibited a linear response over a wide concentration range of L. monocytogenes from 20 to 2×10(6) CFU per mL and was closely correlated with the following relationship: y=9533.3x+1542.3 (R(2)=0.99). Our proposed ABSA platform also provided excellent specificity for the tests to distinguish L. monocytogenes from other Listeria species and other bacterial genera (3 Listeria spp., 4 Salmonella spp., 2 Vibrio spp., 3 Escherichia coli and 3 Shigella spp.). Improvements in the sensitivity and specificity have not only facilitated the reliable detection of L. monocytogenes at extremely low concentrations, but also allowed for the development of a 96-well plate-based routine assay platform for multivalent diagnostics. PMID:25590973

  10. High brightness InP micropillars grown on silicon with Fermi level splitting larger than 1 eV.

    Science.gov (United States)

    Tran, Thai-Truong D; Sun, Hao; Ng, Kar Wei; Ren, Fan; Li, Kun; Lu, Fanglu; Yablonovitch, Eli; Chang-Hasnain, Constance J

    2014-06-11

    The growth of III-V nanowires on silicon is a promising approach for low-cost, large-scale III-V photovoltaics. However, performances of III-V nanowire solar cells have not yet been as good as their bulk counterparts, as nanostructured light absorbers are fundamentally challenged by enhanced minority carriers surface recombination rates. The resulting nonradiative losses lead to significant reductions in the external spontaneous emission quantum yield, which, in turn, manifest as penalties in the open-circuit voltage. In this work, calibrated photoluminescence measurements are utilized to construct equivalent voltage-current characteristics relating illumination intensities to Fermi level splitting ΔF inside InP microillars. Under 1 sun, we show that splitting can exceed ΔF ∼ 0.90 eV in undoped pillars. This value can be increased to values of ΔF ∼ 0.95 eV by cleaning pillar surfaces in acidic etchants. Pillars with nanotextured surfaces can yield splitting of ΔF ∼ 0.90 eV, even though they exhibit high densities of stacking faults. Finally, by introducing n-dopants, ΔF of 1.07 eV can be achieved due to a wider bandgap energy in n-doped wurzite InP, the higher brightness of doped materials, and the extraordinarily low surface recombination velocity of InP. This is the highest reported value for InP materials grown on a silicon substrate. These results provide further evidence that InP micropillars on silicon could be a promising material for low-cost, large-scale solar cells with high efficiency. PMID:24841253

  11. InP nanopore arrays for photoelectrochemical hydrogen generation

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Zhang, Bin; Zhu, Changqing; Wang, Faze; Song, Jingnan; Zhong, Miao; Ma, Li; Shen, Wenzhong

    2016-02-01

    We report a facile and large-scale fabrication of highly ordered one-dimensional (1D) indium phosphide (InP) nanopore arrays (NPs) and their application as photoelectrodes for photoelectrochemical (PEC) hydrogen production. These InP NPs exhibit superior PEC performance due to their excellent light-trapping characteristics, high-quality 1D conducting channels and large surface areas. The photocurrent density of optimized InP NPs is 8.9 times higher than that of planar counterpart at an applied potential of +0.3 V versus RHE under AM 1.5G illumination (100 mW cm-2). In addition, the onset potential of InP NPs exhibits 105 mV of cathodic shift relative to planar control. The superior performance of the nanoporous samples is further explained by Mott-Schottky and electrochemical impedance spectroscopy ananlysis.

  12. Lightweight InP Solar Cells for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation in this Phase I SBIR is the development of a technology which will enable the manufacture of a lightweight, low cost, InP based compound...

  13. Lightweight InP Solar Cells for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation in this Phase II SBIR is the development of a technology which will enable the manufacture of a lightweight, low cost, high radiation resistance InP...

  14. InP Heterojunction Bipolar Transistor Amplifiers to 255 GHz

    Science.gov (United States)

    Radisic, Vesna; Sawdai, Donald; Scott, Dennis; Deal, William; Dang, Linh; Li, Danny; Cavus, Abdullah; To, Richard; Lai, Richard

    2009-01-01

    Two single-stage InP heterojunction bipolar transistor (HBT) amplifiers operate at 184 and 255 GHz, using Northrop Grumman Corporation s InP HBT MMIC (monolithic microwave integrated circuit) technology. At the time of this reporting, these are reported to be the highest HBT amplifiers ever created. The purpose of the amplifier design is to evaluate the technology capability for high-frequency designs and verify the model for future development work.

  15. Electroluminescence of quantum-dash-based quantum cascade laser structures

    International Nuclear Information System (INIS)

    We developed two mid-infrared quantum cascade structures based on InAs quantum dashes. The dashes were embedded either in AlInGaAs lattice-matched to InP or in tensile-strained AlInAs. The devices emit between 7 and 11 μm and are a step forward in the development of quantum cascade lasers based on 3-D confined active regions.

  16. Deep level defects in high temperature annealed InP

    Institute of Scientific and Technical Information of China (English)

    DONG; Zhiyuan; ZHAO; Youwen; ZENG; Yiping; DUAN; Manlong

    2004-01-01

    Deep level defects in high temperature annealed semi-conducting InP have been studied by deep level transient spectroscopy (DLTS). There is obvious difference in the deep defects between as-grown InP, InP annealed in phosphorus ambient and iron phosphide ambient, as far as their quantity and concentration are concerned. Only two defects at 0.24 and 0.64 eV can be detected in InP annealed iniron phosphide ambient,while defects at 0.24, 0.42, 0.54 and 0.64 eV have been detected in InP annealed in phosphorus ambient, in contrast to two defects at 0.49 and 0.64 eV or one defect at 0.13eV in as-grown InP. A defect suppression phenomenon related to iron diffusion process has been observed. The formation mechanism and the nature of the defects have been discussed.

  17. Multivalent hyaluronic acid bioconjugates improve sFlt-1 activity in vitro.

    Science.gov (United States)

    Altiok, Eda I; Santiago-Ortiz, Jorge L; Svedlund, Felicia L; Zbinden, Aline; Jha, Amit K; Bhatnagar, Deepika; Loskill, Peter; Jackson, Wesley M; Schaffer, David V; Healy, Kevin E

    2016-07-01

    Anti-VEGF drugs that are used in conjunction with laser ablation to treat patients with diabetic retinopathy suffer from short half-lives in the vitreous of the eye resulting in the need for frequent intravitreal injections. To improve the intravitreal half-life of anti-VEGF drugs, such as the VEGF decoy receptor sFlt-1, we developed multivalent bioconjugates of sFlt-1 grafted to linear hyaluronic acid (HyA) chains termed mvsFlt. Using size exclusion chromatography with multiangle light scattering (SEC-MALS), SDS-PAGE, and dynamic light scattering (DLS), we characterized the mvsFlt with a focus on the molecular weight contribution of protein and HyA components to the overall bioconjugate size. We found that mvsFlt activity was independent of HyA conjugation using a sandwich ELISA and in vitro angiogenesis assays including cell survival, migration and tube formation. Using an in vitro model of the vitreous with crosslinked HyA gels, we demonstrated that larger mvsFlt bioconjugates showed slowed release and mobility in these hydrogels compared to low molecular weight mvsFlt and unconjugated sFlt-1. Finally, we used an enzyme specific to sFlt-1 to show that conjugation to HyA shields sFlt-1 from protein degradation. Taken together, our findings suggest that mvsFlt bioconjugates retain VEGF binding affinity, shield sFlt-1 from enzymatic degradation, and their movement in hydrogel networks (in vitro model of the vitreous) is controlled by both bioconjugate size and hydrogel network mesh size. These results suggest that a strategy of multivalent conjugation could substantially improve drug residence time in the eye and potentially improve therapeutics for the treatment of diabetic retinopathy. PMID:27086270

  18. The Invasion and Reproductive Toxicity of QDs-Transferrin Bioconjugates on Preantral Follicle in vitro

    Directory of Open Access Journals (Sweden)

    Gaixia Xu, Suxia Lin, Wing-Cheung Law, Indrajit Roy, Xiaotan Lin, Shujiang Mei, Hanwu Ma, Siping Chen, Hanben Niu, Xiaomei Wang

    2012-01-01

    Full Text Available The toxicity of QD has been extensively studied over the past decade. However, the potential toxicity of QDs impedes its use for clinical research. In this work, we established a preantral follicle in vitro culture system to investigate the effects of QD-Transferrin (QDs-Tf bioconjugates on follicle development and oocyte maturation. The preantral follicles were cultured and exposed to CdTe/ZnTe QDs-Tf bioconjugates with various concentrations and the reproductive toxicity was assessed at different time points post-treatment. The invasion of QDs-Tf for oocytes was verified by laser scanning confocal microscope. Steroid production was evaluated by immunoassay. C-band Giemsa staining was performed to observe the chromosome abnormality of oocytes. The results showed that the QDs-Tf bioconjugates could permeate into granulosa cells and theca cells, but not into oocyte. There are no obvious changes of oocyte diameter, the mucification of cumulus-oocyte-complexes and the occurrence of aneulpoidy as compared with the control group. However, delay in the antrum formation and decrease in the ratio of oocytes with first polar body were observed in QDs-Tf-treated groups. The matured oocytes with first polar body decreased significantly by ~16% (from 79.6±10 % to 63±2.9 % when the concentration of QDs-Tf bioconjugates exceeded 2.89 nmol·L-1 (P < 0.05. Our results implied that the CdTe/ZnTe QDs-Tf bioconjugates were reproductive toxic for follicle development, and thus also revealed that this in vitro culture system of preantral follicle is a highly sensitive tool for study on the reproductive toxicity of nanoparticles.

  19. Long-Term INP Measurements within the BACCHUS project

    Science.gov (United States)

    Schrod, Jann; Bingemer, Heinz; Curtius, Joachim

    2016-04-01

    The European research project BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) studies the interactions between aerosols, clouds and the climate system, and tries to reconstruct pre-industrial aerosol and cloud conditions from data collected in pristine environments. The number concentration of Ice Nucleating Particles (INP) is an important, yet scarcely known parameter. As a partner of Work package 1 of BACCHUS we began in September 2014 to operate a globally spanned network of four INP sampling stations, which is the first of its kind. The stations are located at the ATTO observatory in the Brazilian Rainforest, the Caribbean Sea (Martinique), the Zeppelin Observatory at Svalbard in the Arctic, and in central Europe (Germany). Samples are collected routinely every day or every few days by electrostatic precipitation of aerosol particles onto Si substrates. The samples are stored in petri-slides, and shipped to our laboratory in Frankfurt, Germany. The number of ice nucleating particles on the substrate is analyzed in the isothermal static diffusion chamber FRIDGE by growing ice on the INP and photographing and counting the crystals. The measurements in the temperature range from -20°C to -30°C and relative humidities of 100-135% (with respect to ice) address primarily the deposition/condensation nucleation modes. Here we present INP and supporting aerosol data from this novel INP network for the first time.

  20. Electron guns and collectors developed at INP for electron cooling devices

    Energy Technology Data Exchange (ETDEWEB)

    Sharapa, A.N.; Shemyakin, A.V. [Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-09-01

    Institute of Nuclear Physics (INP) has a rich experience in designing electron guns and collectors for electron cooling devices. This paper is a review of the experience of several INP research groups in this field. Some results obtained at INP for systems without a guiding magnetic field are also discussed.

  1. Nanophotonic resonators for InP solar cells.

    Science.gov (United States)

    Goldman, Daniel A; Murray, Joseph; Munday, Jeremy N

    2016-05-16

    We describe high efficiency thin-film InP solar cells that utilize a periodic array of TiO2 nanocylinders. These nanophotonic resonators are found to reduce the solar-weighted average reflectivity of an InP solar cell to ~1.3%, outperforming the best double-layer antireflection coatings. The coupling between Mie scattering resonances and thin-film interference effects accurately describes the optical enhancement provided by the nanocylinders. The spectrally resolved reflectivity and J-V characteristics of the device under AM1.5G illumination are determined via coupled optical and electrical simulations, resulting in a predicted power conversion efficiency > 23%. We conclude that the nanostructured coating reduces reflection without negatively affecting the electronic properties of the InP solar cell by separating the nanostructured optical components from the active layer of the device. PMID:27409965

  2. Particle detectors based on semiconducting InP epitaxial layers

    OpenAIRE

    Yatskiv, R. (Roman); Grym, J.; Žďánský, K. (Karel)

    2011-01-01

    In this work, we present study of electrical properties and detection performance of two types of InP detector structures: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type ...

  3. Palladium nanoparticles on InP for hydrogen detection

    Directory of Open Access Journals (Sweden)

    Zdansky Karel

    2011-01-01

    Full Text Available Abstract Layers of palladium (Pd nanoparticles on indium phosphide (InP were prepared by electrophoretic deposition from the colloid solution of Pd nanoparticles. Layers prepared by an opposite polarity of deposition showed different physical and morphological properties. Particles in solution are separated and, after deposition onto the InP surface, they form small aggregates. The size of the aggregates is dependent on the time of deposition. If the aggregates are small, the layer has no lateral conductance. Forward and reverse I-V characteristics showed a high rectification ratio with a high Schottky barrier height. The response of the structure on the presence of hydrogen was monitored.

  4. Quantum

    CERN Document Server

    Al-Khalili, Jim

    2003-01-01

    In this lively look at quantum science, a physicist takes you on an entertaining and enlightening journey through the basics of subatomic physics. Along the way, he examines the paradox of quantum mechanics--beautifully mathematical in theory but confoundingly unpredictable in the real world. Marvel at the Dual Slit experiment as a tiny atom passes through two separate openings at the same time. Ponder the peculiar communication of quantum particles, which can remain in touch no matter how far apart. Join the genius jewel thief as he carries out a quantum measurement on a diamond without ever touching the object in question. Baffle yourself with the bizzareness of quantum tunneling, the equivalent of traveling partway up a hill, only to disappear then reappear traveling down the opposite side. With its clean, colorful layout and conversational tone, this text will hook you into the conundrum that is quantum mechanics.

  5. Detection of biomolecules and bioconjugates by monitoring rotated grating-coupled surface plasmon resonance

    CERN Document Server

    Szalai, Aniko; Somogyi, Aniko; Szenes, Andras; Banhelyi, Balazs; Csapo, Edit; Dekany, Imre; Csendes, Tibor; Csete, Maria

    2016-01-01

    Plasmonic biosensing chips were prepared by fabricating wavelength-scaled dielectric-metal interfacial gratings on thin polycarbonate films covered bimetal layers via two-beam interference laser lithography. Lysozyme (LYZ) biomolecules and gold nanoparticle (AuNP-LYZ) bioconjugates with 1:5 mass ratio were seeded onto the biochip surfaces. Surface plasmon resonance spectroscopy was performed before and after biomolecule seeding in a modified Kretschmann-arrangement by varying the azimuthal and polar angles to optimize the conditions for rotated grating-coupling. The shift of secondary and primary resonance peaks originating from rotated grating-coupling phenomenon was monitored to detect the biomolecule and bioconjugate adherence. Numerical calculations were performed to reproduce the measured reflectance spectra and the resonance peak shifts caused by different biocoverings. Comparison of measurements and calculations proved that monitoring the narrower secondary peaks under optimal rotated-grating coupling ...

  6. Recent developments in atom transfer radical polymerization initiators for development of polymer-protein bioconjugates

    Directory of Open Access Journals (Sweden)

    AKHILESH KUMAR SHAKYA

    2013-01-01

    Full Text Available One of the major challenges in modern synthetic polymer chemistry is to synthesize end defined polymers of different end functionality with predetermined uniform molecular weight. End functionalized polymers/copolymers basically in block and grafting form are having several potential applications in biomedical areas in the form of surface modifications, coatings, adhesives, and in order to increase the biocompatibility of polymeric blends. Among the existing controlled radical polymerization (CRP methods for synthesis of these functional polymers, the atom transfer radical polymerization (ATRP is one of the powerful techniques. The functional groups in these polymers can be easily introduced at the chain ends through functionalized ATRP initiators. A number of ATRP initiators have been developed in polymer science to develop defined polymer-protein bioconjugates. This critical review basically focuses on different types of ATRP initiators and their mechanisms used in the synthesis of polymer-protein bioconjugates.

  7. Synthetic routes toward functional block copolymers and bioconjugates via RAFT polymerization

    OpenAIRE

    Wiss, Kerstin T.

    2010-01-01

    Synthetic Routes toward Functional Block Copolymers and Bioconjugates via RAFT PolymerizationrnSynthesewege für funktionelle Blockcopolymere und Biohybride über RAFT PolymerisationrnDissertation von Dipl.-Chem. Kerstin T. WissrnIm Rahmen dieser Arbeit wurden effiziente Methoden für die Funktionalisierung beider Polymerkettenenden für Polymer- und Bioanbindung von Polymeren entwickelt, die mittels „Reversible Addition-Fragmentation Chain Transfer“ (RAFT) Polymerisation hergestellt wurden. Zu d...

  8. Growing Applications of “Click Chemistry” for Bioconjugation in Contemporary Biomedical Research

    OpenAIRE

    Nwe, Kido; Martin W. Brechbiel

    2009-01-01

    This update summarizes the growing application of “click” chemistry in diverse areas such as bioconjugation, drug discovery, materials science, and radiochemistry. This update also discusses click chemistry reactions that proceed rapidly with high selectivity, specificity, and yield. Two important characteristics make click chemistry so attractive for assembling compounds, reagents, and biomolecules for preclinical and clinical applications. First, click reactions are bio-orthogonal; neither ...

  9. Potentiometric Urea Biosensor Based on an Immobilised Fullerene-Urease Bio-Conjugate

    OpenAIRE

    Kasra Saeedfar; Lee Yook Heng; Tan Ling Ling; Majid Rezayi

    2013-01-01

    A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease) bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate) (PnBA) membrane entrapped with a hydrogen...

  10. Investigation of helium implantation induced blistering in InP

    International Nuclear Information System (INIS)

    Four-inch InP wafers were implanted with 100 keV helium ions with a dose of 5x1016 cm-2 and subsequently annealed in air in the temperature range of 225-400deg. C in order to determine the blistering kinetics of these wafers. An Arrhenius plot of the blistering time as a function of reciprocal temperature revealed two different activation energies for the formation of surface blisters in InP. The activation energy was found to be 0.30 eV in the higher temperature regime of 300-400 deg. C and 0.74 eV in the lower temperature regime of 225-300 deg. C. The implantation induced damage was analyzed by cross-sectional transmission electron microscopy, which revealed a band of defects extending from 400-700 nm from the surface of InP. The damage band was found to be decorated with a large number of nanovoids having diameters between 2 and 5 nm. These nanovoids served as precursors for the formation of microcracks inside InP upon annealing, which led to the formation of surface blisters

  11. InP solar cell with window layer

    Science.gov (United States)

    Jain, Raj K. (Inventor); Landis, Geoffrey A. (Inventor)

    1994-01-01

    The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

  12. 1990's annual report of INPE's Plasma Associated Laboratory

    International Nuclear Information System (INIS)

    This is the 1990's annual report of INPE's Plasma Associated Laboratory it contains information on current research developed at the laboratory including quiescent plasma, magnetized plasma, plasma centrifuge, plasma and radiation (gyrotron), ionic propulsion, and toroidal plasma. (A.C.A.S.)

  13. Growth and properties of InP single crystals

    Science.gov (United States)

    Dun-fu, Fang; Xiang-xi, Wang; Yong-quan, Xu; Li-tong, Tan

    1984-04-01

    InP single crystals with various dopants including S, Sn, Zn and Fe have been grown successfully by the Czochralski method under high pressure with liquid encapsulation. It is found that by carefully adjusting the thermal symmetry of the heating field and by further improving the quality of the polycrystals and by dehydrating B 2O 3, twin-free InP crystals can be obtained even with a shoulder angle of up to 54°, and defects caused by thermal decomposition appear on the surface of the crystals during pulling. Furthermore, a comparison of the crystal perfection and uniformity between S-doped and Sn-doped InP crystals shows that the quality of the former is better than that of the latter. Dislocation-free Zn-doped p-InP single crystals without precipitates have also been easily obtained when the carrier concentration is greater than 2×10 18 cm -3 and the diameter less than 30 mm. By controlling the iron content, semi-insulating thermally stable single crystals of InP doped with ⩽0.03 wt% of Fe without precipitates and with a homogeneous resistivity can be produced.

  14. c-Myc inhibits TP53INP1 expression via promoter methylation in esophageal carcinoma

    International Nuclear Information System (INIS)

    Research highlights: → TP53INP1 expression is down-regulated in esophageal carcinoma and is associated with CGI-131 methylation. → Inhibition of CGI-131 methylation upregulates TP53INP1 expression in ESCC cell lines. → Ectopic expression of TP53INP1 inhibits growth of ESCC cells by inducing apoptosis and inhibiting cell cycle progression. → c-Myc binds to the promoter of TP53INP1 in vivo and vitro and recruits DNMT3A to TP53INP1 promoter for CGI-131 methylation. -- Abstract: Tumor protein p53-induced nuclear protein 1 (TP53INP1) is a well known stress-induced protein that plays a role in both cell cycle arrest and p53-mediated apoptosis. Loss of TP53INP1 expression has been reported in human melanoma, breast carcinoma, and gastric cancer. However, TP53INP1 expression and its regulatory mechanism in esophageal squamous cell carcinoma (ESCC) remain unclear. Our findings are in agreement with previous reports in that the expression of TP53INP1 was downregulated in 28% (10/36 cases) of ESCC lesions, and this was accompanied by significant promoter methylation. Overexpression of TP53INP1 induced G1 cell cycle arrest and increased apoptosis in ESCC cell lines (EC-1, EC-109, EC-9706). Furthermore, our study showed that the oncoprotein c-Myc bound to the core promoter of TP53INP1 and recruited DNA methyltransferase 3A to methylate the local promoter region, leading to the inhibition of TP53INP1 expression. Our findings revealed that TP53INP1 is a tumor suppressor in ESCC and that c-Myc-mediated DNA methylation-associated silencing of TP53INP1 contributed to the pathogenesis of human ESCC.

  15. Gelatin-nanogold bioconjugates as effective plasmonic platforms for SERS detection and tagging.

    Science.gov (United States)

    Suarasan, Sorina; Focsan, Monica; Maniu, Dana; Astilean, Simion

    2013-03-01

    It is well known that standard citrate-reduced gold nanoparticles (AuNPs) are unstable at high ionic strength solution, which limits their applications in the biomedical field. In this work we present an environmentally friendly approach for the stabilization of citrate-reduced AuNPs in aqueous solution. Specifically, the stability of the AuNPs against salt-induced aggregation was greatly improved in the presence of gelatin biopolymer and stabilization of individual or small assemblies of nanoparticles can be controlled by the amount of gelatin. Furthermore, the gelatin-nanogold bioconjugates were demonstrated to be operational as highly sensitive surface-enhanced Raman scattering (SERS) active substrate for the detection of Rose Bengal fluorophore in solution at very low concentration. The results suggest that such bioconjugates can be successfully employed not only for detection of analytes, but more interestingly for building SERS-active tags in view of imaging purpose. The stabilization of bioconjugates was analyzed by localized surface plasmon resonance spectroscopy (LSPR), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta-potential, and the chemical interaction of gelatin with AuNPs was inferred from Fourier transform infrared spectroscopy (FT-IR). PMID:23261569

  16. In vitro cytotoxicity of the ternary PAMAM G3–pyridoxal–biotin bioconjugate

    Directory of Open Access Journals (Sweden)

    Uram Ł

    2013-12-01

    Full Text Available Łukasz Uram, Magdalena Szuster, Krzysztof Gargasz, Aleksandra Filipowicz, Elżbieta Wałajtys-Rode, Stanisław Wołowiec Cosmetology Department, University of Information Technology and Management in Rzeszów, Rzeszów, Poland Abstract: A third-generation polyamidoamine dendrimer (PAMAM G3 was used as a macromolecular carrier for pyridoxal and biotin. The binary covalent bioconjugate of G3, with nine molecules of biotin per one molecule of G3 (G39B, and the ternary covalent bioconjugate of G3, with nine biotin and ten pyridoxal molecules (G39B10P, were synthesized. The biotin and pyridoxal residues of the bioconjugate were available for carboxylase and transaminase enzymes, as demonstrated in the conversion of pyruvate to oxaloacetate and alanine to pyruvate, respectively, by in vitro monitoring of the reactions, using 1H nuclear magnetic resonance spectroscopy. The toxicity of the ternary bioconjugate (BC-PAMAM was studied in vitro on BJ human normal skin fibroblasts and human squamous cell carcinoma (SCC-15 cell cultures in comparison with PAMAM G3, using three cytotoxicity assays (XTT, neutral red, and crystal violet and an estimation of apoptosis by confocal microscopy detection. The tests have shown that BC-PAMAM has significantly lower cytotoxicity compared with PAMAM. Nonconjugated PAMAM was not cytotoxic at concentrations up to 5 µM (NR and 10 µM (XTT, and BC-PAMAM was not cytotoxic up to 50 µM (both assays for both cell lines. It has been also found that normal fibroblasts were more sensitive than SCC to both PAMAM and BC-PAMAM. The effect of PAMAM and BC-PAMAM on the initiation of apoptosis (PAMAM in fibroblasts at 5 µM and BC-PAMAM at 10 µM in both cell lines corresponded with cytotoxicity assays for both cell lines. We concluded that normal fibroblasts are more sensitive to the cytotoxic effects of the PAMAM G3 dendrimer and that modification of its surface cationic groups by substitution with biologically active molecules

  17. Spontaneous emission control of single quantum dots in bottom-up nanowire waveguides

    NARCIS (Netherlands)

    Bulgarini, G.; Reimer, M.E.; Zehender, T.; Hocevar, M.; Bakkers, E.P.A.M.; Kouwenhoven, L.P.; Zwiller, V.

    2012-01-01

    Nanowire waveguides with controlled shape are promising for engineering the collection efficiency of quantum light sources. We investigate the exciton lifetime in individual InAsP quantum dots, perfectly positioned on-axis of InP nanowire waveguides. We demonstrate control over the quantum dot spont

  18. The X-ray response of InP

    Energy Technology Data Exchange (ETDEWEB)

    Owens, Alan E-mail: aowens@astro.estec.esa.nl; Bavdaz, M.; Gostilo, V.; Gryaznov, D.; Loupilov, A.; Peacock, A.; Sipila, H

    2002-07-21

    We present the results of X-ray measurements on a prototype InP detector. The device was fabricated from Fe-doped bulk material of size 3x3x0.18 mm{sup 3}. X-ray measurements have been carried out using a number of radioactive and fluorescent target sources. The detector energy response function was found to be linear over the energy range 5.9-88 keV with an average rms non-linearity of 0.7%, consistent with statistics. At a detector temperature of -60 deg. C, the FWHM energy resolution under full-area illumination was 2.5 at 5.9 keV rising to 12 at 88 keV. Analysis of the energy resolution function indicates that poor charge transport presently limits the performance of InP detectors.

  19. The X-ray response of InP

    International Nuclear Information System (INIS)

    We present the results of X-ray measurements on a prototype InP detector. The device was fabricated from Fe-doped bulk material of size 3x3x0.18 mm3. X-ray measurements have been carried out using a number of radioactive and fluorescent target sources. The detector energy response function was found to be linear over the energy range 5.9-88 keV with an average rms non-linearity of 0.7%, consistent with statistics. At a detector temperature of -60 deg. C, the FWHM energy resolution under full-area illumination was 2.5 at 5.9 keV rising to 12 at 88 keV. Analysis of the energy resolution function indicates that poor charge transport presently limits the performance of InP detectors

  20. Annealing effect on InP vertical porous arrays

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    InP vertical porous arrays were produced using electrochemical etching at room temperature.The as-etched InP samples were annealed in an ultra high vacuum camber.Cross-sectional analysis of the porous layer was conducted using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).Annealing in vacuum was found to meliorate the structural quality of the porous layer.EDX results showed the composition change of the porous InP.By controlling the annealing process parameters,the content ratio of phosphorus (P) to indium (In) is tuneable.Raman property of the samples was also investigated at room temperature.Compared with the sample without annealing treatment,Raman spectrum from the annealed sample showed red-shifted LO and TO peaks together with sharpened LO peak and shortened TO peak.

  1. A single crystalline InP nanowire photodetector

    Science.gov (United States)

    Yan, Xin; Li, Bang; Wu, Yao; Zhang, Xia; Ren, Xiaomin

    2016-08-01

    Single crystalline nanowires are critical for achieving high-responsivity, high-speed, and low-noise nanoscale photodetectors. Here, we report a metal-semiconductor-metal photodetector based on a single crystalline InP nanowire. The nanowires are grown by a self-catalyzed method and exhibit stacking-fault-free zinc blende crystal structure. The nanowire exhibits a typical n-type semiconductor property and shows a low room temperature dark current of several hundred pA at moderate biases. A photoresponsivity of 6.8 A/W is obtained at a laser power density of 0.2 mW/cm2. This work demonstrates that single crystalline InP nanowires are good candidates for future optoelectronic device applications.

  2. Defining capabilities of Si and InP photonics.

    Energy Technology Data Exchange (ETDEWEB)

    Vawter, Gregory Allen

    2010-05-01

    Monolithic photonic integrated circuits (PICs) have a long history reaching back more than 40 years. During that time, and particularly in the past 15 years, the technology has matured and the application space grown to span sophisticated tunable diode lasers, 40 Gb/s electrical-to-optical signal converters with complex data formats, wavelength multiplexors and routers, as well as chemical/biological sensors. Most of this activity has centered in recent years on optical circuits built on either Silicon or InP substrates. This talk will review the three classes of PIC and highlight the unique strengths, and weaknesses, of PICs based on Silicon and InP substrates. Examples will be provided from recent R&D activity.

  3. Electron Spin Relaxation in Intrinsic Bulk InP Semiconductor

    CERN Document Server

    Ma, Hong; Wang, Lihua; Ma, Guohong

    2010-01-01

    Electron spin dynamics is studied by time resolved pump probe reflectivity (TRPPR) technique using the co- and counter-circularly polarized femtosecond pulses in intrinsic bulk Indium Phosphide (InP) crystal at room temperature and 70 K. The reflectivity change from bleaching into absorption enhancement is observed with increasing pump photon energy. This phenomenon can be explained in terms of the spin sensitive band filling and band gap renormalization effects. Although electron spin relaxation process at room temperature is much faster than that at 70K, carrier density dependence of electron spin relaxation shows similar tendency. With increasing carrier density, the electron spin relaxation time increases initially and then decreases after reaching a maximum value. Our experimental results agree well with the recent theoretical prediction and D'yakonov-Perel' mechanism is considered as a dominating contribution to the electron spin relaxation in intrinsic bulk InP semiconductor.

  4. Brittle-to-ductile transition temperature in InP

    Energy Technology Data Exchange (ETDEWEB)

    Bayu-Aji, Leonardus B. [School of Education, Universitas Pelita Harapan, M. H. Thamrin Boulevard, 15811 Tangerang (Indonesia); Pirouz, P. [Department of Materials Science and Engineering, Case Western Reserve University, 44106 Cleveland, Ohio (United States)

    2010-05-15

    Deformation experiments were conducted on monocrystalline InP by 4-point bend tests as well as by conventional and depth-sensing indentation (DSI) tests. Temperature ranges where the material exhibited a brittle or a ductile behavior were investigated with particular focus on the transition from one deformation mode to the other. The 4-point bend tests show that InP exhibits a sharp brittle-to-ductile transition (BDT) temperature within 5 between 350 and 355 C at a strain rate of 2.9 x 10{sup -5} s{sup -1}. The indentation BDT (IBDT) temperature is found to be significantly lower at {proportional_to}250 C. The difference of nearly 100 C between the two techniques is attributed to the hydrostatic component of the indentation stress field that suppresses fracture and shifts the transition to a lower temperature. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  5. Azimuthally polarized cathodoluminescence from InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Brenny, B. J. M.; Osorio, C. I.; Polman, A., E-mail: polman@amolf.nl [Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands); Dam, D. van [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Gómez Rivas, J. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); FOM Institute DIFFER, P.O. Box 6336, 5600 HH Eindhoven (Netherlands)

    2015-11-16

    We determine the angle and polarization dependent emission from 1.75 µm and 2.50 µm long InP nanowires by using cathodoluminescence polarimetry. We excite the vertical wires using a 5 keV electron beam, and find that the 880 nm bandgap emission shows azimuthally polarized rings, with the number of rings depending on the wire height. The data agree well with a model in which spontaneous emission from the wire emitted into the far field interferes with emission reflected off the substrate. From the model, the depth range from which the emission is generated is found to be up to 400 nm below the top surface of the wires, well beyond the extent of the primary electron cloud. This enables a probe of the carrier diffusion length in the InP nanowires.

  6. Study of discharge in quiescent plasma machine of the INPE

    International Nuclear Information System (INIS)

    Measurements of principal plasma parameters produced by quiescent plasma machine of the Instituto de Pesquisas Espaciais (INPE) for current of 500 mA and several values of pressure and discharge power are presented. A qualitative interpretation for obtained results is done and a simple model for plasma density is compared with experimental values. The conditions of cathode operation are also investigated. (M.C.K.)

  7. Indium and phosphorus vacancies and antisites in InP

    OpenAIRE

    Seitsonen, A. P.; Virkkunen, R.; Puska, Martti J.; Nieminen, Risto M.

    1994-01-01

    We present an extensive study of the structure and energetics of monovacancies and antisites in InP. Using a first-principles approach, the different charge states of indium and phosphorus vacancies and antisites are examined. The lattice distortions around the defects are derived fully self-consistently with respect to both electronic and ionic degrees of freedom. Jahn-Teller relaxations, defect-induced one-electron energy levels, and ionization potentials in the band gap are discussed. From...

  8. Bioconjugation of neutral protease on silk fibroin nanoparticles and application in the controllable hydrolysis of sericin.

    Science.gov (United States)

    Zhu, Lin; Hu, Ren-Ping; Wang, Hai-Yan; Wang, Yuan-Jing; Zhang, Yu-Qing

    2011-09-28

    Bombyx mori silk fibroin is a protein-based macromolecular biopolymer with remarkable biocompatibility. Silk fiber was degummed and subjected to a series of treatments, including dissolution and dialysis, to yield an aqueous solution of silk fibroin, which was introduced rapidly into excess acetone to produce crystalline silk fibroin nanoparticles (SFNs). The SFNs were conjugated covalently with a neutral protease (NP) using glutaraldehyde as the cross-linking reagent. The objective of this study was to determine the optimal conditions for biosynthesis of the SFN-NP bioconjugates. First, SFN-NP was obtained by covalent cross-linking of SFN and NP at an SFN/NP ratio of 5-8 mg:1 IU with 0.75% glutaraldehyde for 6 h at 25 °C. When adding 50 IU of the enzyme, the residual activity of biological conjugates was increased to 31.45%. Studies on the enzyme activity of SFN-NP and its kinetics showed that the stability of SFN-NP bioconjugates was greater than that of the free enzyme, the optimum reactive temperature range was increased by 5-10 °C, and the optimum pH value range was increased to 6.5-8.0. Furthermore, the thermal stability was improved to some extent. A controlled hydrolysis test using the poorly water-soluble protein sericin as a substrate and SFN-NP as the enzyme showed that the longer the reaction time (within 1 h), the smaller the molecular mass (<30 kDa) is of the sericin peptide produced. The SFN-NP bioconjugate is easily recovered by centrifugation and can be used repeatedly. The highly efficient processing technology and the use of SFN as a novel vector for a protease has great potential for research and the development of food processing. PMID:21846144

  9. Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

    International Nuclear Information System (INIS)

    A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV–Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets’ surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50–100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high

  10. TP53inp1 Gene Is Implicated in Early Radiation Response in Human Fibroblast Cells

    Directory of Open Access Journals (Sweden)

    Nikolett Sándor

    2015-10-01

    Full Text Available Tumor protein 53-induced nuclear protein-1 (TP53inp1 is expressed by activation via p53 and p73. The purpose of our study was to investigate the role of TP53inp1 in response of fibroblasts to ionizing radiation. γ-Ray radiation dose-dependently induces the expression of TP53inp1 in human immortalized fibroblast (F11hT cells. Stable silencing of TP53inp1 was done via lentiviral transfection of shRNA in F11hT cells. After irradiation the clonogenic survival of TP53inp1 knockdown (F11hT-shTP cells was compared to cells transfected with non-targeting (NT shRNA. Radiation-induced senescence was measured by SA-β-Gal staining and autophagy was detected by Acridine Orange dye and microtubule-associated protein-1 light chain 3 (LC3B immunostaining. The expression of TP53inp1, GDF-15, and CDKN1A and alterations in radiation induced mitochondrial DNA deletions were evaluated by qPCR. TP53inp1 was required for radiation (IR induced maximal elevation of CDKN1A and GDF-15 expressions. Mitochondrial DNA deletions were increased and autophagy was deregulated following irradiation in the absence of TP53inp1. Finally, we showed that silencing of TP53inp1 enhances the radiation sensitivity of fibroblast cells. These data suggest functional roles for TP53inp1 in radiation-induced autophagy and survival. Taken together, we suppose that silencing of TP53inp1 leads radiation induced autophagy impairment and induces accumulation of damaged mitochondria in primary human fibroblasts.

  11. Bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles as novel tumor targeting carriers

    International Nuclear Information System (INIS)

    In this study, we have developed a novel carrier, micelle-type bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles (NPs), for the detection and treatment of pancreatic cancer. These NPs contained 4-arm-PEG as corona, and PLGA as core, the particle surface was conjugated with cyclo(arginine-glycine-aspartate) (cRGD) as ligand for in vivo tumor targeting. The hydrodynamic size of the NPs was determined to be 150-180 nm and the critical micellar concentration (CMC) was estimated to be 10.5 mg l-1. Our in vitro study shows that these NPs by themselves had negligible cytotoxicity to human pancreatic cancer (Panc-1) and human glioblastoma (U87) cell lines. Near infrared (NIR) microscopy and flow cytometry demonstrated that the cRGD conjugated PLGA-4-arm-PEG polymeric NPs were taken up more efficiently by U87MG glioma cells, over-expressing the αvβ3 integrin, when compared with the non-targeted NPs. Whole body imaging showed that the cRGD conjugated PLGA-4-arm-PEG branched polymeric NPs had the highest accumulation in the pancreatic tumor site of mice at 48 h post-injection. Physical, hematological, and pathological assays indicated low in vivo toxicity of this NP formulation. These studies on the ability of these bioconjugated PLGA-4-arm-PEG polymeric NPs suggest that the prepared polymeric NPs may serve as a promising platform for detection and targeted drug delivery for pancreatic cancer.

  12. Overview of the main methods used to combine proteins with nanosystems: absorption, bioconjugation, and encapsulation

    Directory of Open Access Journals (Sweden)

    Mariagrazia Di Marco

    2009-12-01

    Full Text Available Mariagrazia Di Marco1, Shaharum Shamsuddin2, Khairunisak Abdul Razak3, Azlan Abdul Aziz4, Corinne Devaux1, Elsa Borghi1, Laurent Levy1, Claudia Sadun51Nanobiotix, Paris, France; 2School of Health Sciences, Health Campus Universiti Sains Malaysia, Kelantan, Malaysia; 3School of Materials and Mineral Resources Engineering, Engineering Campus, 4School of Physics, Universiti Sains Malaysia, Penang, Malaysia; 5Department of Chemistry, Sapienza, University of Rome, Rome, ItalyAbstract: The latest development of protein engineering allows the production of proteins having desired properties and large potential markets, but the clinical advances of therapeutical proteins are still limited by their fragility. Nanotechnology could provide optimal vectors able to protect from degradation therapeutical biomolecules such as proteins, enzymes or specific polypeptides. On the other hand, some proteins can be also used as active ligands to help nanoparticles loaded with chemotherapeutic or other drugs to reach particular sites in the body. The aim of this review is to provide an overall picture of the general aspects of the most successful approaches used to combine proteins with nanosystems. This combination is mainly achieved by absorption, bioconjugation and encapsulation. Interactions of nanoparticles with biomolecules and caveats related to protein denaturation are also pointed out. A clear understanding of nanoparticle-protein interactions could make possible the design of precise and versatile hybrid nanosystems. This could further allow control of their pharmacokinetics as well as activity, and safety.Keywords: nanoparticles, drug delivery, proteins, polypeptides, absorption, bioconjugation, encapsulation

  13. High-Yield Growth and Characterization of ⟨100⟩ InP p-n Diode Nanowires.

    Science.gov (United States)

    Cavalli, Alessandro; Wang, Jia; Esmaeil Zadeh, Iman; Reimer, Michael E; Verheijen, Marcel A; Soini, Martin; Plissard, Sebastien R; Zwiller, Val; Haverkort, Jos E M; Bakkers, Erik P A M

    2016-05-11

    Semiconductor nanowires are nanoscale structures holding promise in many fields such as optoelectronics, quantum computing, and thermoelectrics. Nanowires are usually grown vertically on (111)-oriented substrates, while (100) is the standard in semiconductor technology. The ability to grow and to control impurity doping of ⟨100⟩ nanowires is crucial for integration. Here, we discuss doping of single-crystalline ⟨100⟩ nanowires, and the structural and optoelectronic properties of p-n junctions based on ⟨100⟩ InP nanowires. We describe a novel approach to achieve low resistance electrical contacts to nanowires via a gradual interface based on p-doped InAsP. As a first demonstration in optoelectronic devices, we realize a single nanowire light emitting diode in a ⟨100⟩-oriented InP nanowire p-n junction. To obtain high vertical yield, which is necessary for future applications, we investigate the effect of the introduction of dopants on the nanowire growth. PMID:27045232

  14. Coupled optical and electrical study of thin-film InGaAs photodetector integrated with surface InP Mie resonators

    Science.gov (United States)

    Fu, Dong; Liu, Jietao; Song, Jiakun; Yu, Hailong; Zhang, Zuyin; Wang, Wenbo; Xu, Yun; Song, Guofeng; Wei, Xin

    2016-03-01

    High-index dielectric and semiconductor nanostructures with characteristics of low absorption loss and artificially controlled scattering properties have grasped an increasing attention for improving the performance of thin-film photovoltaic devices. In this work, combined optical and electrical simulations were performed for thin-film InP/In0.53Ga0.47As/InP hetero-junction photodetector with periodically arranged InP nano-cylinders in the in-coupling configuration. It is found that the carefully designed InP nano-cylinders possess strongly substrate-coupled Mie resonances and can effectively couple incident light into the guided mode, both of which significantly increase optical absorption. Further study from the electrical aspects shows that enhancement of external quantum efficiency is as high as 82% and 83% in the configurations with the optimized nano-cylinders and the optimized period, respectively. Moreover, we demonstrate that the integration of InP nano-cylinders does not degrade the electrical performance, since the surface recombination is effectively suppressed by separating the absorber layer where carriers generate and the air/semiconductor interface. The comprehensive modeling including optical and electrical perspectives provides a more practical description for device performance than the optical-only simulation and is expected to advance the design of thin-film absorber layer based optoelectronic devices for fast response and high efficiency.

  15. All-optical signal processing using InP photonic-crystal nanocavity switches

    DEFF Research Database (Denmark)

    Yu, Yi; Vukovic, Dragana; Heuck, Mikkel;

    2014-01-01

    In this paper, we present recent progress in experimental characterization of InP photonic-crystal nanocavity switches. Pump-probe measurements on an InP PhC H0 cavity show large-contrast ultrafast switching at low pulse energy. At large pulse energies, a large resonance shift passing across the ...

  16. InP HEMT Integrated Circuits for Submillimeter Wave Radiometers in Earth Remote Sensing

    Science.gov (United States)

    Deal, William R.; Chattopadhyay, Goutam

    2012-01-01

    The operating frequency of InP integrated circuits has pushed well into the Submillimeter Wave frequency band, with amplification reported as high as 670 GHz. This paper provides an overview of current performance and potential application of InP HEMT to Submillimeter Wave radiometers for earth remote sensing.

  17. Growth of semi-insulating InP through nuclear doping

    International Nuclear Information System (INIS)

    Full text : Semi-insulating semiconductors are widely used in so-called dielectronics. Dielectric devices have quick response, good frequency characteristics, a low noise level, low sensitivity to temperature changes, etc. One of the most promising semiconductor materials is InP. At present annealing and doping are commonly used techniques to grow semi-insulating InP. The aim of this work was to grow semi-insulating InP through nuclear doping (by irradiation with gamma-quanta). InP single crystals were obtained by Czochralski method. Specimens were irradiated with doses of 10kGr at room temperature. Electrical conductivity and Hall effect were measured before and after irradiation in the temperature range 77 to 320K. After irradiation reduction in electrical conductivity was observed. This fact can be associated with formation of M-centers in positively threefold charged states of vacancy and antisite defects. Under irradiation first Ini interstitial atoms and phosphorus vacancies form. Further, the Ini atoms occupy the phosphorus vacancies. As a result there appear InP antiste defects, which along with indium vacancies form VInInp+ Inp++ complexes of the acceptor type. These complexes turn out to be traps for charge carriers and electrical conductivity of irradiated InP are sharply reduced to semi-insulating specimens

  18. All-optical signal processing using InP photonic-crystal nanocavity switches

    DEFF Research Database (Denmark)

    Yu, Yi; Vukovic, Dragana; Heuck, Mikkel; Peucheret, Christophe; Oxenløwe, Leif Katsuo; Yvind, Kresten; Mørk, Jesper

    2014-01-01

    In this paper, we present recent progress in experimental characterization of InP photonic-crystal nanocavity switches. Pump-probe measurements on an InP PhC H0 cavity show large-contrast ultrafast switching at low pulse energy. At large pulse energies, a large resonance shift passing across the...

  19. Spectroscopic properties of colloidal indium phosphide quantum wires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin-Wang; Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry; Gibbons, Patrick C.; Wang, Lin-Wang; Janes, David B.; Buhro, William E.

    2008-07-11

    Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photo-oxidation, without a significant influence on quantum-wire photoluminescence. However, photo-oxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation, and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.

  20. Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

    Directory of Open Access Journals (Sweden)

    Jeyran eShahbazi

    2013-05-01

    Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

  1. Synthesis of Aldehyde-Linked Nucleotides and DNA and Their Bioconjugations with Lysine and Peptides through Reductive Amination

    Czech Academy of Sciences Publication Activity Database

    Raindlová, Veronika; Pohl, Radek; Hocek, Michal

    2012-01-01

    Roč. 18, č. 13 (2012), s. 4080-4087. ISSN 0947-6539 R&D Projects: GA ČR GA203/09/0317 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleotides * aldehydes * DNA * reductive amination * bioconjugations Subject RIV: CC - Organic Chemistry Impact factor: 5.831, year: 2012

  2. Design, synthesis, and evaluation of cisplatin-containing EGFR targeting bioconjugates as potential therapeutic agents for brain tumors

    Science.gov (United States)

    Barth, Rolf F; Wu, Gong; Meisen, W Hans; Nakkula, Robin J; Yang, Weilian; Huo, Tianyao; Kellough, David A; Kaumaya, Pravin; Turro, Claudia; Agius, Lawrence M; Kaur, Balveen

    2016-01-01

    The aim of this study was to evaluate four different platinated bioconjugates containing a cisplatin (cis-diamminedichloroplatinum [cis-DDP]) fragment and epidermal growth factor receptor (EGFR)-targeting moieties as potential therapeutic agents for the treatment of brain tumors using a human EGFR-expressing transfectant of the F98 rat glioma (F98EGFR) to assess their efficacy. The first two bioconjugates employed the monoclonal antibody cetuximab (C225 or Erbitux®) as the targeting moiety, and the second two used genetically engineered EGF peptides. C225-G5-Pt was produced by reacting cis-DDP with a fifth-generation polyamidoamine dendrimer (G5) and then linking it to C225 by means of two heterobifunctional reagents. The second bioconjugate (C225-PG-Pt) employed the same methodology except that polyglutamic acid was used as the carrier. The third and fourth bioconjugates used two different EGF peptides, PEP382 and PEP455, with direct coordination to the Pt center of the cis-DDP fragment. In vivo studies with C225-G5-Pt failed to demonstrate therapeutic activity following intracerebral (ic) convection-enhanced delivery (CED) to F98EGFR glioma-bearing rats. The second bioconjugate, C225-PG-Pt, failed to show in vitro cytotoxicity. Furthermore, because of its high molecular weight, we decided that lower molecular weight peptides might provide better targeting and microdistribution within the tumor. Both PEP382-Pt and PEP455-Pt bioconjugates were cytotoxic in vitro and, based on this, a pilot study was initiated using PEP455-Pt. The end point for this study was tumor size at 6 weeks following tumor cell implantation and 4 weeks following ic CED of PEP455-Pt to F98 glioma-bearing rats. Neuropathologic examination revealed that five of seven rats were either tumor-free or only had microscopic tumors at 42 days following tumor implantation compared to a mean survival time of 20.5 and 26.3 days for untreated controls. In conclusion, we have succeeded in reformatting the

  3. Gate tunable monolayer MoS{sub 2}/InP heterostructure solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shisheng, E-mail: shishenglin@zju.edu.cn; Wang, Peng; Li, Xiaoqiang; Wu, Zhiqian; Xu, Zhijuan; Zhang, Shengjiao; Xu, Wenli [College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China)

    2015-10-12

    We demonstrate monolayer molybdenum disulfide (MoS{sub 2})/indium phosphide (InP) van der Waals heterostructure with remarkable photovoltaic response. Furthermore, benefiting from the atomically thin and semiconductor nature of MoS{sub 2}, we have designed the gate tunable MoS{sub 2}/InP heterostructure. Applied with a top gate voltage, the Fermi level of MoS{sub 2} is effectively tuned, and the barrier height at the MoS{sub 2}/InP heterojunction correspondingly changes. The power conversion efficiency of MoS{sub 2}/InP solar cells has reached a value of 7.1% under AM 1.5G illumination with a gate voltage of +6 V. The tunable MoS{sub 2}/InP heterostructure may be promising for highly efficient solar cells.

  4. Particle detectors based on InP Schottky diodes

    International Nuclear Information System (INIS)

    A study of electrical properties and detection performance of Indium Phosphide detector structures with Schottky contacts prepared on high purity p-type InP was performed. Schottky barrier detectors were prepared by vacuum evaporation of Pd on p-type epitaxial layers grown on Zn-doped p-type substrates. The detection performance of the detectors was characterized by the measurement of pulse-height spectra with alpha particles emitted from 241Am source at room temperature. The influence of the quality of p-type epitaxial layers on the charge-collection efficiency and energy resolution in the full-width half-maximum is discussed.

  5. Phosphorus vacancy in InP: A negative- U center

    OpenAIRE

    Alatalo, M.; Nieminen, Risto M.; Puska, Martti J.; Seitsonen, A. P.; Virkkunen, R.

    1993-01-01

    Using first-principles simulations, we identify the phosphorous vacancy in InP as a negative-U center. The deep levels associated with this defect are in the upper half of the band gap, and the charge state changes directly from positive to negative as the Fermi level is raised: the vacancy captures two electrons rather than one. We also obtain the relaxed structures and formation energies for the In and P vacancies as a function of both electron and atomic chemical potentials. Peer reviewed

  6. Radiation material science at the INP AS RUz

    International Nuclear Information System (INIS)

    Among the critical technologies, determining the national priority of USA and Russia the first place is taken by manufacturing new materials. It means synthesis and production of materials for electronics (micro- and nano-) and photonics, ceramics and nano-ceramics, composites, metals and alloys with particular properties, super-hard materials, bio-compatible materials, catalysts and membranes. Radiation solid state physics gave birth of many radiation technologies for obtaining unique new or modified materials. In the table lists the experimental results recently obtained at the INP AS RUz. The studies are supported by grants of STCU and Uzbekistan Center of Science and Technology

  7. Micro-Raman and micro-photoluminescence study of bio-conjugated core–shell CdSe/ZnS nanocrystals

    International Nuclear Information System (INIS)

    The micro-Raman and micro-photoluminescence spectra of non-conjugated and conjugated with antibody against S6K2 commercial CdSe/ZnS quantum dots (QDs) were investigated under different excitation wavelengths and at different temperatures. In the photoluminescence (PL) spectra, the additional PL band shifted on 0.6–0.65 eV to higher energies from the CdSe/ZnS QD exciton PL band is revealed. The relative intensity of this band is found to be several times larger in bio-conjugated QDs, than in the non-conjugated ones. The characteristics of both PL bands (the PL intensity, spectral position and half-width of the PL band) vary similarly under continuous laser light irradiation, storage of the QD samples in the atmospheric ambience as well as during the temperature change. In the Raman spectra recorded under excitation resonant with the high-energy PL band, the additional Raman peaks at about 300 cm−1 and 600 cm−1, which are close to the frequency of LO and 2LO phonons of bulk CdS, are found. It is proposed that alloyed QDs with chemical composition close to CdS are responsible for the additional high-energy PL band. The possible reasons for the formation of the alloyed QDs are discussed

  8. Micro-Raman and micro-photoluminescence study of bio-conjugated core–shell CdSe/ZnS nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Borkovska, L., E-mail: bork@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics of NASU, pr. Nauky 41, 03028 Kyiv (Ukraine); Korsunska, N.; Stara, T.; Kolomys, O.; Strelchuk, V. [V. Lashkaryov Institute of Semiconductor Physics of NASU, pr. Nauky 41, 03028 Kyiv (Ukraine); Rachkov, O. [The Institute of Molecular Biology and Genetics of NASU, Zabolotnogo Str. 150, 03680 Kyiv (Ukraine); Kryvko, A. [Instituto Politécnico Nacional – ESIME, Av. IPN, Ed. Z4, U.P.A.L.M., 07738 Mexico D.F. (Mexico)

    2014-11-15

    The micro-Raman and micro-photoluminescence spectra of non-conjugated and conjugated with antibody against S6K2 commercial CdSe/ZnS quantum dots (QDs) were investigated under different excitation wavelengths and at different temperatures. In the photoluminescence (PL) spectra, the additional PL band shifted on 0.6–0.65 eV to higher energies from the CdSe/ZnS QD exciton PL band is revealed. The relative intensity of this band is found to be several times larger in bio-conjugated QDs, than in the non-conjugated ones. The characteristics of both PL bands (the PL intensity, spectral position and half-width of the PL band) vary similarly under continuous laser light irradiation, storage of the QD samples in the atmospheric ambience as well as during the temperature change. In the Raman spectra recorded under excitation resonant with the high-energy PL band, the additional Raman peaks at about 300 cm{sup −1} and 600 cm{sup −1}, which are close to the frequency of LO and 2LO phonons of bulk CdS, are found. It is proposed that alloyed QDs with chemical composition close to CdS are responsible for the additional high-energy PL band. The possible reasons for the formation of the alloyed QDs are discussed.

  9. Design, Synthesis and Applications of Hyaluronic Acid-Paclitaxel Bioconjugatesâ€

    Directory of Open Access Journals (Sweden)

    Rinaldo Marini Bettolo

    2008-02-01

    Full Text Available Paclitaxel (1a, a well known antitumor agent adopted mainly for the treatmentof breast and ovarian cancer, suffers from significant disadvantages such as low solubility,certain toxicity and specific drug-resistance of some tumor cells. To overcome theseproblems extensive research has been carried out. Among the various proposed strategies,the conjugation of paclitaxel (1a to a biocompatible polymer, such as hyaluronic acid(HA, 2, has also been considered. Coupling a bioactive compound to a biocompatiblepolymer offers, in general, many advantages such as better drug solubilization, betterstabilization, specific localization and controlled release. Hereafter the design, synthesisand applications of hyaluronic acid-paclitaxel bioconjugates are reviewed. An overview ofHA-paclitaxel combinations is also given.

  10. Stable Poly(methacrylic acid Brush Decorated Silica Nano-Particles by ARGET ATRP for Bioconjugation

    Directory of Open Access Journals (Sweden)

    Marcello Iacono

    2015-08-01

    Full Text Available The synthesis of polymer brush decorated silica nano-particles is demonstrated by activator regeneration by electron transfer atom transfer radical polymerization (ARGET ATRP grafting of poly(tert-butyl methacrylate. ATRP initiator decorated silica nano-particles were obtained using a novel trimethylsiloxane derivatised ATRP initiator obtained by click chemistry. Comparison of de-grafted polymers with polymer obtained from a sacrificial initiator demonstrated good agreement up to 55% monomer conversion. Subsequent mild deprotection of the tert-butyl ester groups using phosphoric acid yielded highly colloidal and pH stable hydrophilic nano-particles comprising approximately 50% methacrylic acid groups. The successful bio-conjugation was achieved by immobilization of Horseradish Peroxidase to the polymer brush decorated nano-particles and the enzyme activity demonstrated in a conversion of o-phenylene diamine dihydrochloride assay.

  11. PRINT: A Protein Bioconjugation Method with Exquisite N-terminal Specificity

    Science.gov (United States)

    Sur, Surojit; Qiao, Yuan; Fries, Anja; O'Meally, Robert N.; Cole, Robert N.; Kinzler, Kenneth W.; Vogelstein, Bert; Zhou, Shibin

    2015-12-01

    Chemical conjugation is commonly used to enhance the pharmacokinetics, biodistribution, and potency of protein therapeutics, but often leads to non-specific modification or loss of bioactivity. Here, we present a simple, versatile and widely applicable method that allows exquisite N-terminal specific modification of proteins. Combining reversible side-chain blocking and protease mediated cleavage of a commonly used HIS tag appended to a protein, we generate with high yield and purity exquisitely site specific and selective bio-conjugates of TNF-α by using amine reactive NHS ester chemistry. We confirm the N terminal selectivity and specificity using mass spectral analyses and show near complete retention of the biological activity of our model protein both in vitro and in vivo murine models. We believe that this methodology would be applicable to a variety of potentially therapeutic proteins and the specificity afforded by this technique would allow for rapid generation of novel biologics.

  12. Bioconjugation of lipase and cholesterol oxidase with graphene or graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Rubens A.; Souza, Michele L.; Bloisi, Georgia D.; Corio, Paolo; Petri, Denise F. S., E-mail: dfsp@iq.usp.br [Universidade de São Paulo, Instituto de Química (Brazil)

    2015-04-15

    The catalytic behavior of lipase and cholesterol oxidase (ChOx) in the absence and in the presence of graphene (G) or graphene oxide (GO) was investigated at 24 ± 1 °C and pH 6.5. GO flat sheets (0.5–2 μm) were ∼2-nm thick, while G formed aggregates. The maximum reaction velocity (V{sub max}) values and turnover numbers (k{sub cat}) determined for reactions catalyzed by physical mixtures of lipase (at 0.01 g l{sup −1}) or ChOx (at 0.03 g l{sup −1}) and G (0.012 g l{sup −1}) increased six-fold or doubled, respectively, in comparison to neat enzymes. Circular dichroism (CD) and photoluminescence (PL) spectroscopic measurements revealed the preservation of native secondary structures of enzymes and bioconjugation driven by hydrophobic interaction and energy transfer (redshift) between lipase or ChOx and G, corroborating with the enhanced catalytic behavior. On the other hand, the interactions between GO, which has hydrophilic moieties on the basal plane, and ChOx caused enzyme deactivation, as evidenced by the absence of typical CD signal. At low GO concentration (<0.012 g l{sup −1}), bioconjugates of lipases with GO led to V{sub max} and k{sub cat} values four-fold lower than their counterparts with G, but the GO hydrophilic groups probably favored the affinity for the substrate, because the Michaelis constant (K{sub m}) values decreased in comparison to that of neat lipase. Upon increasing the GO concentration, lipases lost secondary structure and the typical lipase PL bands disappeared.

  13. Bioconjugation of lipase and cholesterol oxidase with graphene or graphene oxide

    International Nuclear Information System (INIS)

    The catalytic behavior of lipase and cholesterol oxidase (ChOx) in the absence and in the presence of graphene (G) or graphene oxide (GO) was investigated at 24 ± 1 °C and pH 6.5. GO flat sheets (0.5–2 μm) were ∼2-nm thick, while G formed aggregates. The maximum reaction velocity (Vmax) values and turnover numbers (kcat) determined for reactions catalyzed by physical mixtures of lipase (at 0.01 g l−1) or ChOx (at 0.03 g l−1) and G (0.012 g l−1) increased six-fold or doubled, respectively, in comparison to neat enzymes. Circular dichroism (CD) and photoluminescence (PL) spectroscopic measurements revealed the preservation of native secondary structures of enzymes and bioconjugation driven by hydrophobic interaction and energy transfer (redshift) between lipase or ChOx and G, corroborating with the enhanced catalytic behavior. On the other hand, the interactions between GO, which has hydrophilic moieties on the basal plane, and ChOx caused enzyme deactivation, as evidenced by the absence of typical CD signal. At low GO concentration (<0.012 g l−1), bioconjugates of lipases with GO led to Vmax and kcat values four-fold lower than their counterparts with G, but the GO hydrophilic groups probably favored the affinity for the substrate, because the Michaelis constant (Km) values decreased in comparison to that of neat lipase. Upon increasing the GO concentration, lipases lost secondary structure and the typical lipase PL bands disappeared

  14. Potentiometric Urea Biosensor Based on an Immobilised Fullerene-Urease Bio-Conjugate

    Directory of Open Access Journals (Sweden)

    Kasra Saeedfar

    2013-12-01

    Full Text Available A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate (PnBA membrane entrapped with a hydrogen ionophore. This pH-selective membrane is intended to function as a potentiometric urea biosensor with the deposition of C60-urease on the PnBA membrane. Various parameters for fullerene modification and urease immobilization were investigated. The optimal pH and concentration of the phosphate buffer for the urea biosensor were 7.0 and 0.5 mM, respectively. The linear response range of the biosensor was from 2.31 × 10−3 M to 8.28 × 10−5 M. The biosensor’s sensitivity was 59.67 ± 0.91 mV/decade, which is close to the theoretical value. Common cations such as Na+, K+, Ca2+, Mg2+ and NH4+ showed no obvious interference with the urea biosensor’s response. The use of a fullerene-urease bio-conjugate and an acrylic membrane with good adhesion prevented the leaching of urease enzyme and thus increased the stability of the urea biosensor for up to 140 days.

  15. Radiation damage in InP single crystals and solar cells

    International Nuclear Information System (INIS)

    This paper shows that InP solar cell is more radiation resistant than Si and GaAs solar cells. 60Co γ-ray irradiation damage in InP solar cells was examined. Changes in minority carrier diffusion length and carrier concentration in irradiated InP single crystals were also investigated by electron beam induced current and capacitance-voltage methods for solar cells. A high carrier concentration p-InP substrate has lower concentration damage. Thus, an InP solar cell with a higher carrier concentration substrate has superior radiation resistance. Experimental results for radiation damage in InP solar cells were in satisfactory agreement with theoretical values, calculated from changes in minority carrier diffusion length and carrier concentration due to irradiation. Numerical analysis suggests that an InP solar cell with a higher carrier concentration substrate and a shallower junction should be relatively more radiation resistant. Annealing behavior for radiation damage in InP was also examined

  16. Growth of polycrystalline InP thin films by the pulsed laser deposition technique

    International Nuclear Information System (INIS)

    The growth of polycrystalline InP films on glass substrates by the pulsed laser deposition technique is reported. Optimal growth conditions as high vacuum and relatively low substrate temperature were necessary to obtain stoichiometric InP layers. Structural and morphological characterizations of the samples are shown. X-ray diffraction shows that the stoichiometric InP films were face-centered cubic with preferred orientation of the crystallites over the (111) plane and mean grain size of about 60 nm. We also discuss the consequences of adverse growth conditions as bad vacuum and high substrate temperature on the film stoichiometry

  17. Growth of polycrystalline InP thin films by the pulsed laser deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Iribarren, A. [Instituto de Materiales y Reactivos, Universidad de La Habana, Zapata y G, Vedado, Plaza, Havana 10400 (Cuba)]. E-mail: augusto@fisica.uh.cu; Castro-Rodriguez, R. [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310, Merida Yucatan (Mexico); Ponce-Cabrera, L. [CICATA-IPN, Altamira, Km. 14.5 Carretera Tampico-Puerto Industrial, Altamira 89600, Tamps. (Mexico); Pena, J.L. [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310, Merida Yucatan (Mexico)

    2006-07-03

    The growth of polycrystalline InP films on glass substrates by the pulsed laser deposition technique is reported. Optimal growth conditions as high vacuum and relatively low substrate temperature were necessary to obtain stoichiometric InP layers. Structural and morphological characterizations of the samples are shown. X-ray diffraction shows that the stoichiometric InP films were face-centered cubic with preferred orientation of the crystallites over the (111) plane and mean grain size of about 60 nm. We also discuss the consequences of adverse growth conditions as bad vacuum and high substrate temperature on the film stoichiometry.

  18. Radiation resistance of InP solar cells under light illumination

    International Nuclear Information System (INIS)

    The demonstration of superior radiation resistance of InP solar cells during solar cell operation is reported. High-energy electron irradiation effects on InP n+-p junction solar cells under light illumination are compared with those under dark conditions. The InP solar cells under light illumination are found to have less degradation in solar cell properties. This is explained by minority-carrier injection enhanced annealing of radiation-induced defects, analyzed using deep level transient spectroscopy, in the p-InP layer

  19. High performance 1689-nm quantum well diode lasers

    Institute of Scientific and Technical Information of China (English)

    Yupeng Duan; Tao Lin; Cuiluan Wang; Feng Chong; Xiaoyu Ma

    2007-01-01

    @@ 1689-nm diode lasers used in medical apparatus have been fabricated and characterized. The lasers had pnpn InP current confinement structure, and the active region consisted of 5 pairs of InGaAs quantum wells and InGaAsP barriers.

  20. Polymersomes prepared from thermoresponsive fluorescent protein-polymer bioconjugates: capture of and report on drug and protein payloads.

    Science.gov (United States)

    Wong, Chin Ken; Laos, Alistair J; Soeriyadi, Alexander H; Wiedenmann, Jörg; Curmi, Paul M G; Gooding, J Justin; Marquis, Christopher P; Stenzel, Martina H; Thordarson, Pall

    2015-04-27

    Polymersomes provide a good platform for targeted drug delivery and the creation of complex (bio)catalytically active systems for research in synthetic biology. To realize these applications requires both spatial control over the encapsulation components in these polymersomes and a means to report where the components are in the polymersomes. To address these twin challenges, we synthesized the protein-polymer bioconjugate PNIPAM-b-amilFP497 composed of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and a green-fluorescent protein variant (amilFP497). Above 37 °C, this bioconjugate forms polymersomes that can (co-)encapsulate the fluorescent drug doxorubicin and the fluorescent light-harvesting protein phycoerythrin 545 (PE545). Using fluorescence lifetime imaging microscopy and Förster resonance energy transfer (FLIM-FRET), we can distinguish the co-encapsulated PE545 protein inside the polymersome membrane while doxorubicin is found both in the polymersome core and membrane. PMID:25736460

  1. Particle detectors based on semiconducting InP epitaxial layers

    Science.gov (United States)

    Yatskiv, R.; Grym, J.; Zdansky, K.

    2011-01-01

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature.

  2. Particle detectors based on semiconducting InP epitaxial layers

    Energy Technology Data Exchange (ETDEWEB)

    Yatskiv, R; Grym, J; Zdansky, K, E-mail: yatskiv@ufe.cz [Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Praha 8 (Czech Republic)

    2011-01-15

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 10{sup 14} cm{sup -3} grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from {sup 241}Am source at room temperature.

  3. Particle detectors based on semiconducting InP epitaxial layers

    International Nuclear Information System (INIS)

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature.

  4. Study of discharge in the quiescent plasma machine of INPE

    International Nuclear Information System (INIS)

    Measurements of main plasma parameters produced in the quiescent plasma machine of INPE for several pressure and discharge potential values, and current of 500 m A are presented. The density varies form 108 cm-3 to 1010 cm-3 and the average electron energy is between 1 eV and 10 eV. The electron energy distribution is non-Maxwellian corresponding to one population of high energy primary electrons and two populations of electron with temperature below 10 eV. The plasma potential varies from 1 V to 3 V in relation to the anode, but decrease fastly to negative values when the pressures becomes near to 10-3 Pa. Qualitative interpretations are given and a simple model for plasma density is compared with experimental values. Conditions of cathode operation are also investigated. (M.C.K.)

  5. Preliminary design of the INPE's Solar Vector Magnetograph

    CERN Document Server

    Vieira, L E A; Lago, A Dal; Wrasse, C; Echer, E; Guarnieri, F L; Cardoso, F Reis; Guerrero, G; Costa, J Rezende; Palacios, J; Balmaceda, L; Alves, L Ribeiro; da Silva, L; Costa, L L; Sampaio, M; Soares, M C Rabello; Barbosa, M; Domingues, M; Rigozo, N; Mendes, O; Jauer, P; Dallaqua, R; Branco, R H; Stekel, T; Gonzalez, W; Kabata, W

    2016-01-01

    We describe the preliminary design of a magnetograph and visible-light imager instrument to study the solar dynamo processes through observations of the solar surface magnetic field distribution. The instrument will provide measurements of the vector magnetic field and of the line-of-sight velocity in the solar photosphere. As the magnetic field anchored at the solar surface produces most of the structures and energetic events in the upper solar atmosphere and significantly influences the heliosphere, the development of this instrument plays an important role in reaching the scientific goals of The Atmospheric and Space Science Coordination (CEA) at the Brazilian National Institute for Space Research (INPE). In particular, the CEA's space weather program will benefit most from the development of this technology. We expect that this project will be the starting point to establish a strong research program on Solar Physics in Brazil. Our main aim is acquiring progressively the know-how to build state-of-art sol...

  6. Experimental studies on the surface confined quiescent plasma at INPE

    International Nuclear Information System (INIS)

    Quiescent plasma machines are being used in several experiments at the Associated Plasma Laboratory in INPE. The research activities comprises particle simulation studies on ion acoustic double Layers, and studies on the plasma production and loss in surface confined magnetic multidipole thermionic discharges. Recent results from these studies have shown a non-maxwellian plasma formed in most of the discharge conditions. The plasma leakage through the multidipole fields shows an anomalous diffusion process driven by ion acoustic turbulence in the magnetic sheath. The information derived from these studies are being used in the construction and characterization of ion sources for shallow ion implantation in semiconductors, in ion thruster for space propulsion and in the development of powerful ion sources for future use in neutral beam injection systems. (author)

  7. Ultra-Fast Low Energy Switching Using an InP Photonic Crystal H0 Nanocavity

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel;

    2013-01-01

    Pump-probe measurements on InP photonic crystal H0 nanocavities show large-contrast ultrafast switching at low pulse energy. For large pulse energies, high-frequency carrier density oscillations are induced, leading to pulsesplitting....

  8. INPE LANDSAT-D thematic mapper computer compatible tape format specification

    Science.gov (United States)

    Parada, N. D. J. (Principal Investigator); Desouza, R. C. M.

    1982-01-01

    The format of the computer compatible tapes (CCT) which contain Thematic Mapper (TM) imagery data acquired from the LANDSAT D and D Prime satellites by the INSTITUTO DE PERSQUISAS ESPACIALS (CNPq-INPE/BRAZIL) is defined.

  9. Extended Wavelength InP Based Avalanche Diodes for MWIR Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For this NASA STTR program, we propose to develop a novel superlattice-based near infrared to midwave infrared avalanche photodetector (APD) grown on InP substrates...

  10. Structural analysis of erbium {delta}-doped InP by OMVPE with RBS-channeling

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, Junji; Takeda, Hitoshi; Matsubara, Naoki; Tabuchi, Masao; Fujiwara, Yasufumi; Morita, Kenji; Takeda, Yoshikazu [Nagoya Univ. (Japan). School of Engineering

    1997-03-01

    We have determined the lattice location of Er in InP {delta}-doped by OMVPE with RBS-channeling. Er concentrations along the <001> and <011> directions are same as random yields, while a significant flux peaking effect is seen for the <111> direction. These data suggest that Er atoms occupy the site equivalent to the hexahedral site in InP lattice. (author)

  11. Exciton dynamics in near-surface InGaN quantum wells coupled to colloidal nanocrystals

    DEFF Research Database (Denmark)

    Kopylov, Oleksii; Shirazi, Roza; Yvind, Kresten;

    2013-01-01

    We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN.......We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN....

  12. Exciton dynamics in near-surface InGaN quantum wells coupled to colloidal nanocrystals

    DEFF Research Database (Denmark)

    Kopylov, Oleksii; Shirazi, Roza; Yvind, Kresten; Kardynal, Beata

    We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN.......We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN....

  13. Fluorescent cholesterol sensing using enzyme-modified CdSe/ZnS quantum dots

    International Nuclear Information System (INIS)

    CdSe/ZnS quantum dot nanocrystals with wurtzite structure were synthesized using trioctylphosphine oxide (TOPO) templates. For biological applications, the capping surfactants, TOPO were replaced with mercaptoacetic acid (MAA). The carboxylic groups in MAA were activated by esterification of n-hydroxysulfo-succinimide (sulfo-NHS) catalyzed by water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), namely through the EDC/NHS coupling reaction. MAA not only provided water solubility to CdSe/ZnS quantum dots but also acted as a linker between cholesterol oxidase (COx) and the quantum dots due to its carboxyl group. The CdSe/ZnS–COx bioconjugates showed sensitive and linear decrease in the photoluminescence (PL) peak intensity with cholesterol concentration up to 9 mM. The PL intensity variation was elucidated based upon collisional quenching by hydrogen peroxide generated from the enzymatic oxidation reaction between COx and cholesterol. This collisional quenching mechanism was confirmed by monitoring the response of bovine serum albumin-modified CdSe/ZnS bioconjugates to cholesterol molecules. Furthermore, the bioconjugates showed specificity to cholesterol molecules due to selective enzymatic oxidation reaction by COx. A simple quantum dot-based optical biosensor is proposed for precision cholesterol detection.

  14. Fluorescent cholesterol sensing using enzyme-modified CdSe/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Eun [Korea University, Department of Materials Science and Engineering (Korea, Republic of); Kim, Tae Geun [Korea University, Department of Electronic Engineering (Korea, Republic of); Sung, Yun-Mo, E-mail: ymsung@korea.ac.kr [Korea University, Department of Materials Science and Engineering (Korea, Republic of)

    2012-10-15

    CdSe/ZnS quantum dot nanocrystals with wurtzite structure were synthesized using trioctylphosphine oxide (TOPO) templates. For biological applications, the capping surfactants, TOPO were replaced with mercaptoacetic acid (MAA). The carboxylic groups in MAA were activated by esterification of n-hydroxysulfo-succinimide (sulfo-NHS) catalyzed by water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), namely through the EDC/NHS coupling reaction. MAA not only provided water solubility to CdSe/ZnS quantum dots but also acted as a linker between cholesterol oxidase (COx) and the quantum dots due to its carboxyl group. The CdSe/ZnS-COx bioconjugates showed sensitive and linear decrease in the photoluminescence (PL) peak intensity with cholesterol concentration up to 9 mM. The PL intensity variation was elucidated based upon collisional quenching by hydrogen peroxide generated from the enzymatic oxidation reaction between COx and cholesterol. This collisional quenching mechanism was confirmed by monitoring the response of bovine serum albumin-modified CdSe/ZnS bioconjugates to cholesterol molecules. Furthermore, the bioconjugates showed specificity to cholesterol molecules due to selective enzymatic oxidation reaction by COx. A simple quantum dot-based optical biosensor is proposed for precision cholesterol detection.

  15. Design, synthesis, and evaluation of cisplatin-containing EGFR targeting bioconjugates as potential therapeutic agents for brain tumors

    Directory of Open Access Journals (Sweden)

    Barth RF

    2016-05-01

    Full Text Available Rolf F Barth,1 Gong Wu,1 W Hans Meisen,2 Robin J Nakkula,1 Weilian Yang,1 Tianyao Huo,1 David A Kellough,1 Pravin Kaumaya,3–5 Claudia Turro,6 Lawrence M Agius,7 Balveen Kaur2 1Department of Pathology, 2Department of Neurological Surgery, 3Department of Obstetrics and Gynecology, 4Department of Molecular and Cellular Biochemistry, 5Department of Microbiology, 6Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA; 7Department of Pathology, Mater Dei Hospital, University of Malta Medical School, Msida, Malta Abstract: The aim of this study was to evaluate four different platinated bioconjugates containing a cisplatin (cis-diamminedichloroplatinum [cis-DDP] fragment and epidermal growth factor receptor (EGFR-targeting moieties as potential therapeutic agents for the treatment of brain tumors using a human EGFR-expressing transfectant of the F98 rat glioma (F98EGFR to assess their efficacy. The first two bioconjugates employed the monoclonal antibody cetuximab (C225 or Erbitux® as the targeting moiety, and the second two used genetically engineered EGF peptides. C225-G5-Pt was produced by reacting cis-DDP with a fifth-generation polyamidoamine dendrimer (G5 and then linking it to C225 by means of two heterobifunctional reagents. The second bioconjugate (C225-PG-Pt employed the same methodology except that polyglutamic acid was used as the carrier. The third and fourth bioconjugates used two different EGF peptides, PEP382 and PEP455, with direct coordination to the Pt center of the cis-DDP fragment. In vivo studies with C225-G5-Pt failed to demonstrate therapeutic activity following intracerebral (ic convection-enhanced delivery (CED to F98EGFR glioma-bearing rats. The second bioconjugate, C225-PG-Pt, failed to show in vitro cytotoxicity. Furthermore, because of its high molecular weight, we decided that lower molecular weight peptides might provide better targeting and microdistribution within the tumor. Both PEP

  16. A Synthetic Carbohydrate Conjugate Vaccine Candidate against Shigellosis: Improved Bioconjugation and Impact of Alum on Immunogenicity.

    Science.gov (United States)

    van der Put, Robert M F; Kim, Tae Hee; Guerreiro, Catherine; Thouron, Françoise; Hoogerhout, Peter; Sansonetti, Philippe J; Westdijk, Janny; Stork, Michiel; Phalipon, Armelle; Mulard, Laurence A

    2016-04-20

    Conjugation chemistry is among the most important parameters governing the efficacy of glycoconjugate vaccines. High robustness is required to ensure high yields and batch to batch reproducibility. Herein, we have established a robust bioconjugation protocol based on the thiol-maleimide addition. Major variables were determined and acceptable margins were investigated for a synthetic pentadecasaccharide-tetanus toxoid conjugate, which is a promising vaccine candidate against Shigella flexneri serotype 2a infection. The optimized process is applicable to any thiol-equipped hapten and provides an efficient control of the hapten:carrier ratio. Moreover, comparison of four S. flexneri 2a glycoconjugates only differing by their pentadecasaccharide:tetanus toxoid ratio confirmed preliminary findings indicating that hapten loading is critical for immunogenicity with an optimal ratio here in the range of 17 ± 5. In addition, the powerful influence of alum on the immunogenicity of a Shigella synthetic carbohydrate-based conjugate vaccine candidate is demonstrated for the first time, with a strong anti-S. flexneri 2a antibody response sustained for more than one year. PMID:26918643

  17. Design of Novel Relaxase Substrates Based on Rolling Circle Replicases for Bioconjugation to DNA Nanostructures

    Science.gov (United States)

    Sagredo, Sandra; de la Cruz, Fernando; Moncalián, Gabriel

    2016-01-01

    During bacterial conjugation and rolling circle replication, HUH endonucleases, respectively known as relaxases and replicases, form a covalent bond with ssDNA when they cleave their target sequence (nic site). Both protein families show structural similarity but limited amino acid identity. Moreover, the organization of the inverted repeat (IR) and the loop that shape the nic site differs in both proteins. Arguably, replicases cleave their target site more efficiently, while relaxases exert more biochemical control over the process. Here we show that engineering a relaxase target by mimicking the replicase target, results in enhanced formation of protein-DNA covalent complexes. Three widely different relaxases, which belong to MOBF, MOBQ and MOBP families, can properly cleave DNA sequences with permuted target sequences. Collaterally, the secondary structure that the permuted targets acquired within a supercoiled plasmid DNA resulted in poor conjugation frequencies underlying the importance of relaxase accessory proteins in conjugative DNA processing. Our results reveal that relaxase and replicase targets can be interchangeable in vitro. The new Rep substrates provide new bioconjugation tools for the design of sophisticated DNA-protein nanostructures. PMID:27027740

  18. Creation and suppression of point defects through a kick-out substitution process of Fe in InP

    OpenAIRE

    Fung, S; Zhao, YW; Dong, HW; Chen, YH; Zhang, YH; Jiao, JH; Zhao, JQ; Lin, LY

    2002-01-01

    Indium antisite defect In P-related photoluminescence has been observed in Fe-diffused semi-insulating (SI) InP. Compared to annealed undoped or Fe-predoped SI InP, there are fewer defects in SI InP obtained by long-duration, high-temperature Fe diffusion. The suppression of the formation of point defects in Fe-diffused SI InP can be explained in terms of the complete occupation by Fe at indium vacancy. The In P defect is enhanced by the indium interstitial that is caused by the kick out of I...

  19. Spontaneous emission control of single quantum dots in bottom-up nanowire waveguides

    OpenAIRE

    Bulgarini, Gabriele; Reimer, Michael E.; Zehender, Tilman; Hocevar, Moïra; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.; Zwiller, Valery

    2012-01-01

    Nanowire waveguides with controlled shape are promising for engineering the collection efficiency of quantum light sources. We investigate the exciton lifetime in individual InAsP quantum dots, perfectly positioned on-axis of InP nanowire waveguides. We demonstrate control over the quantum dot spontaneous emission by varying the nanowire diameter in e-beam patterned arrays, which modifies the coupling efficiency of the emitter to the fundamental waveguide mode. The spontaneous emission rate i...

  20. Extracellular biosynthesis of gadolinium oxide (Gd2O3 nanoparticles, their biodistribution and bioconjugation with the chemically modified anticancer drug taxol

    Directory of Open Access Journals (Sweden)

    Shadab Ali Khan

    2014-03-01

    Full Text Available As a part of our programme to develop nanobioconjugates for the treatment of cancer, we first synthesized extracellular, protein-capped, highly stable and well-dispersed gadolinium oxide (Gd2O3 nanoparticles by using thermophilic fungus Humicola sp. The biodistribution of the nanoparticles in rats was checked by radiolabelling with Tc-99m. Finally, these nanoparticles were bioconjugated with the chemically modified anticancer drug taxol with the aim of characterizing the role of this bioconjugate in the treatment of cancer. The biosynthesized Gd2O3 nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM, X-ray diffraction (XRD and X-ray photoemission spectroscopy (XPS. The Gd2O3–taxol bioconjugate was confirmed by UV–vis spectroscopy and fluorescence microscopy and was purified by using high performance liquid chromatography (HPLC.

  1. Mode Competition in Dual-Mode Quantum Dots Semiconductor Microlaser

    OpenAIRE

    Chusseau, Laurent; Philippe, Fabrice; Viktorovitch, Pierre; Letartre, Xavier

    2013-01-01

    This paper describes the modeling of quantum dots lasers with the aim of assessing the conditions for stable cw dual-mode operation when the mode separation lies in the THz range. Several possible models suited for InAs quantum dots in InP barriers are analytically evaluated, in particular quantum dots electrically coupled through a direct exchange of excitation by the wetting layer or quantum dots optically coupled through the homogeneous broadening of their optical gain. A stable dual-mode ...

  2. Opto-spintronics in InP using ferromagnetic tunnel spin filters

    International Nuclear Information System (INIS)

    We demonstrate opto-spintronics using Fe-doped Indium Phosphide (InP). The method is based on optical orientation of InP conduction electron spins which are electrically detected in planar InP/oxide/Ni tunnel spin filters. We separate the optical excitation from electrical detection, avoiding thus additional interactions of photons with the ferromagnet. Interface engineering provides a surface iron accumulation and semiconducting Fe:In2O3 in the oxide tunnel barrier. The spin filtering effect switches to positive or negative asymmetry, depending on the Fe concentration in Fex:InP. With respect to the Fe-like electronic structure of these oxides, we can explain the opposite spin selection mechanisms as interface effects. In the temperature region where the InP mobility peaks, we find a maximum of spin-dependent asymmetry of ∼9% in semi-insulating Fe:InP (001), and show the electrical spin detection in hyperpolarized InP also at room temperature. Such robust electronic spin detection in an InP nanodevice is planned to complement dynamic nuclear polarization experiments. (fast track communication)

  3. Aminophosphines: A Double Role in the Synthesis of Colloidal Indium Phosphide Quantum Dots.

    Science.gov (United States)

    Tessier, Mickael D; De Nolf, Kim; Dupont, Dorian; Sinnaeve, Davy; De Roo, Jonathan; Hens, Zeger

    2016-05-11

    Aminophosphines have recently emerged as economical, easy-to-implement precursors for making InP nanocrystals, which stand out as alternative Cd-free quantum dots for optoelectronic applications. Here, we present a complete investigation of the chemical reactions leading to InP formation starting from InCl3 and tris(dialkylamino)phosphines. Using nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction, we demonstrate that injection of the aminophosphine in the reaction mixture is followed by a transamination with oleylamine, the solvent of the reaction. In addition, mass spectrometry and NMR indicate that the formation of InP concurs with that of tetra(oleylamino)phosphonium chloride. The chemical yield of the InP formation agrees with this 4 P(+III) → P(-III) + 3 P(+V) disproportionation reaction occurring, since full conversion of the In precursor was only attained for a 4:1 P/In ratio. Hence it underlines the double role of the aminophosphine as both precursor and reducing agent. These new insights will guide further optimization of high quality InP quantum dots and might lead to the extension of synthetic protocols toward other pnictide nanocrystals. PMID:27111735

  4. Synthesis, formation mechanism and electric property of hollow InP nanospheres

    International Nuclear Information System (INIS)

    Hollow InP nanospheres with the diameters of 700-800 nm and a shell thickness of about 100 nm have been synthesized via a solvothermal reaction of InCl3 with NH4F, red phosphorus and KBH4 in ethylenediamine-ethylene glycol solution at 220 C for 24 h and subsequent HCl treatment. The hollow nanospheres are constructed from nanoparticles with a cubic structure and the sizes of 35 to 40 nm. The hollow InP nanospheres were formed by the cooperative action of H2 bubble templates and InOHF2 limitation. Electric property of the as-synthesized hollow InP nanospheres has been investigated, and the hollow nanospheres could serve as ideal functional components for photoelectronic devices. (orig.)

  5. Electron irradiation damage in N+-P InP solar cells

    International Nuclear Information System (INIS)

    Electron (1 MeV) irradiation damage in shallow n+-p InP solar cells has been studied. An n+-p junction was formed by thermal diffusion of sulphur into a p-type substrate. Minority carrier diffusion length and carrier concentration studies were carried out for defects induced by electron irradiation in InP solar cells. It has been found that the InP solar cell has a higher resistance to radiation degradation than a GaAs solar cell. A cell using a high carrier concentration (order of 1018 cm-3) substrate is more radiation resistant than that with a low carrier concentration (1015 about 1016 cm-3) substrate. Electron irradiation damage dynamics during annealing have also been studied. Damage recovery starts from as low as 700C

  6. Label swapper device for spectral amplitude coded optical packet networks monolithically integrated on InP.

    Science.gov (United States)

    Muñoz, P; García-Olcina, R; Habib, C; Chen, L R; Leijtens, X J M; de Vries, T; Robbins, D; Capmany, J

    2011-07-01

    In this paper the design, fabrication and experimental characterization of an spectral amplitude coded (SAC) optical label swapper monolithically integrated on Indium Phosphide (InP) is presented. The device has a footprint of 4.8x1.5 mm2 and is able to perform label swapping operations required in SAC at a speed of 155 Mbps. The device was manufactured in InP using a multiple purpose generic integration scheme. Compared to previous SAC label swapper demonstrations, using discrete component assembly, this label swapper chip operates two order of magnitudes faster. PMID:21747509

  7. A symbolically defined InP double heterojunction bipolar transistor large-signal model

    Institute of Scientific and Technical Information of China (English)

    Cao Yuxiong; Jin Zhi; Ge Ji; Su Yongbo; Liu Xinyu

    2009-01-01

    A self-built accurate and flexible large-signal model based on an analysis of the characteristics of InP double heterojunction bipolar transistors (DHBTs) is implemented as a seven-port symbolically defined device (SDD)in Agilent ADS. The model accounts for most physical phenomena incluaing the self-heating effect, Kirk effect, soft knee effect, base collector capacitance and collector transit time. The validity and the accuracy of the large-signal model are assessed by comparing the simulation with the measurement of DC, multi-bias small signal S parameters for InP DHBTs.

  8. Conductivity of nanoporous InP membranes investigated using terahertz spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merchant, S K E; Lloyd-Hughes, J; Parkinson, P; Herz, L M; Johnston, M B [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Sirbu, L; Tiginyanu, I M [National Centre for Materials Study and Testing, Technical University of Moldova, and Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, MD-2004 (Moldova, Republic of)], E-mail: s.merchant@physics.ox.ac.uk, E-mail: m.johnston@physics.ox.ac.uk

    2008-10-01

    We have investigated the terahertz conductivity of extrinsic and photoexcited electrons in nanoporous indium phosphide (InP) at different pore densities and orientations. The form of electronic transport in the film was found to differ significantly from that for bulk InP. While photo-generated electrons showed Drude-like transport, the behaviour for extrinsic electrons deviated significantly from the Drude model. Time-resolved photoconductivity measurements found that carrier recombination was slow, with lifetimes exceeding 1 ns for all porosities and orientations. When considered together, these findings suggest that the surfaces created by the nanopores strongly alter the dynamics of both extrinsic and photoexcited electrons.

  9. Self-assembly structure formation on patterned InP surfaces

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Self-assembly of polystyrene spheres guided by patterned n-type InP substrates has been investigated. InP surfaces were patterned using a variety of methods including wet chemical etching,sputter coating,thermal evaporation,and photo lithography. The self-assembly of polystyrene spheres depended on the appearance of patterns and was affected by the deposition techniques (sputter coating and thermal evaporation) of Au micro-squares. SEM and AFM were used to characterize the surface morphologies.

  10. Effect of substrate orientation on the catalyst-free growth of InP nanowires

    International Nuclear Information System (INIS)

    We report the fabrication of self-catalysed InP nanowires on (111)B, (111)A, (110), and (001) InP substrates. Indium droplets, deposited in situ using metalorganic vapour phase epitaxy, are used as seeds for nanowire growth. The preferential nanowire growth direction is always on (111)B (111)A, and (110) oriented substrates. On (111)A substrates some initial growth in the [111]A direction is observed before kinking into one of the available B directions. The nanowires are optically active at room temperature. On (001) substrates no nanowire growth off the substrate is observed. However, growth still takes place in the two possible equivalent B azimuthal directions

  11. Saturation broadening effect in an InP photonic-crystal nanocavity switch

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel;

    2014-01-01

    Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA.......Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA....

  12. Design procedure for millimeter-wave InP DHBT stacked power amplifiers

    DEFF Research Database (Denmark)

    Squartecchia, Michele; Johansen, Tom Keinicke; Midili, Virginio

    2015-01-01

    The stacked-transistor concept for power amplifiers (PA) has been investigated in this work. Specifically, this architecture has been applied in the design of millimeter-wave monolithic microwave integrated circuits (MMICs) using indium phosphide (InP) double heterojunction bipolar transistors...... gives 13.1 dBm of output power, 10.1 dB of gain and 13 % of PAE. To the best of the authors' knowledge, this is the first investigation of multi-level stacked PAs based on InP HBT technology....

  13. Beyond G-band : a 235 GHz InP MMIC amplifier

    Science.gov (United States)

    Dawson, Douglas; Samoska, Lorene; Fung, A. K.; Lee, Karen; Lai, Richard; Grundbacher, Ronald; Liu, Po-Hsin; Raja, Rohit

    2005-01-01

    We present results on an InP monolithic millimeter- wave integrated circuit (MMIC) amplifier having 10-dB gain at 235 GHz. We designed this circuit and fabricated the chip in Northrop Grumman Space Technology's (NGST) 0.07- m InP high electron mobility transistor (HEMT) process. Using a WR3 (220-325 GHz) waveguide vector network analyzer system interfaced to waveguide wafer probes, we measured this chip on-wafer for -parameters. To our knowledge, this is the first time a WR3 waveguide on-wafer measurement system has been used to measure gain in a MMIC amplifier above 230 GHz.

  14. AFM observation of OMVPE-grown ErP on InP substrates using a new organometal tris(ethylcyclopentadienyl)erbium (Er(EtCp)3)

    International Nuclear Information System (INIS)

    ErP has been grown on InP(0 0 1) substrates by organometallic vapor phase epitaxy (OMVPE) using a new liquid organic Er source: tris(ethylcyclopentadienyl)erbium (Er(EtCp)3). Morphological change of an ErP layer on InP(0 0 1) is investigated together with that of an overgrown capping InP layer. Optimum growth condition of InP causes islanding on over-monolayer-ErP. A relatively low overgrowth temperature of InP is a key factor for attaining complete capping coverage on ErP

  15. AFM observation of OMVPE-grown ErP on InP substrates using a new organometal tris(ethylcyclopentadienyl)erbium (Er(EtCp){sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Akane, T.; Jinno, S.; Yang, Y.; Kuno, T.; Hirata, T.; Isogai, Y.; Watanabe, N.; Fujiwara, Y.; Nakamura, A.; Takeda, Y

    2003-06-30

    ErP has been grown on InP(0 0 1) substrates by organometallic vapor phase epitaxy (OMVPE) using a new liquid organic Er source: tris(ethylcyclopentadienyl)erbium (Er(EtCp){sub 3}). Morphological change of an ErP layer on InP(0 0 1) is investigated together with that of an overgrown capping InP layer. Optimum growth condition of InP causes islanding on over-monolayer-ErP. A relatively low overgrowth temperature of InP is a key factor for attaining complete capping coverage on ErP.

  16. Structural and electrical properties of metamorphic nanoheterostructures with a high InAs content (37–100%) grown on GaAs and InP substrates

    International Nuclear Information System (INIS)

    A complex study of the structural and electrical properties of nanoheterostructures containing a metamorphic barrier with a high InAs content (37–100%) in the active region have been performed by the Van der Pauw and X-ray diffraction methods. All peaks observed in the rocking curves for the samples studied (throughout the entire structure) have been revealed and identified. It is shown that, having properly chosen the design of the metamorphic buffer and the compositional gradient in it, one can obtain mobilities and concentrations of the 2D electron gas in the InxGa1−xAs quantum well in the heterostructures formed on GaAs substrates that are comparable with the corresponding values for the nanoheterostructures grown on InP substrates. It is established that the mobility and concentration of 2D electron gas depend both on the metamorphic barrier design and on the structural quality of heterostructure as a whole.

  17. Electric field effect on the emission rate of H4F and H4S hole traps in InP

    International Nuclear Information System (INIS)

    The electric field effect on the emission rate enhancement of the H4F and H4S hole trap in highly Zn-doped InP has been examined using the deep level transient spectroscopy (DLTS) and double correlation DLTS (DDLTS). The DLTS and DDLTS results have been found to be in good agreement for low and intermediate electric fields, but they disagree for large field effect. Comparing our emission data with the theory, we have found that H4F obeys the quantum model of phonon-assisted tunneling while H4S follows the Poole-Frenkel model employing a three-dimensional screening coulombic potential. Our results show that the H4S defect can be attributed to a charged (Vp - Zn) complex. (author)

  18. Electric field effect on the emission rate of H4F and H4S hole traps in InP

    Science.gov (United States)

    Darwich, R.; Alek, B.

    2009-05-01

    The electric field effect on the emission rate enhancement of the H4F and H4S hole trap in highly Zn-doped InP has been examined using the deep level transient spectroscopy (DLTS) and double correlation DLTS (DDLTS). The DLTS and DDLTS results have been found to be in good agreement for low and intermediate electric fields, but they disagree for large field effect. Comparing our emission data with the theory, we have found that H4F obeys the quantum model of phonon-assisted tunneling, while H4S follows the Poole-Frenkel model employing a three-dimensional screening Coulombic potential. Our results show that the H4S defect can be attributed to a charged (Vp-Zn ) complex.

  19. Bioconjugation of trypsin onto gold nanoparticles: Effect of surface chemistry on bioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Hinterwirth, Helmut; Lindner, Wolfgang [Department of Analytical Chemistry, University of Vienna, Waehringerstrasse 38, 1090 Vienna (Austria); Laemmerhofer, Michael, E-mail: michael.laemmerhofer@uni-tuebingen.de [Department of Analytical Chemistry, University of Vienna, Waehringerstrasse 38, 1090 Vienna (Austria)

    2012-07-06

    Highlights: Black-Right-Pointing-Pointer Size and spacer affect bioactivity of nanoparticulate trypsin reactor. Black-Right-Pointing-Pointer Increase of GNP's size increases activity of bound trypsin. Black-Right-Pointing-Pointer Increase of spacer length increases amount and activity of immobilized enzyme by factor 6. Black-Right-Pointing-Pointer Decrease of digestion time up to less than 1 h when trypsin immobilized onto GNPs. Black-Right-Pointing-Pointer Reduced auto-digestion compared to trypsin in-solution. - Abstract: The systematic study of activity, long-time stability and auto-digestion of trypsin immobilized onto gold nanoparticles (GNPs) is described in this paper and compared to trypsin in-solution. Thereby, the influence of GNP's size and immobilization chemistry by various linkers differing in lipophilicity/hydrophilicity and spacer lengths was investigated with regard to the bioactivity of the conjugated enzyme. GNPs with different sizes were prepared by reduction and simultaneous stabilization with trisodium citrate and characterized by UV/vis spectra, dynamic light scattering (DLS), {zeta}-potential measurements and transmission electron microscopy (TEM). GNPs were derivatized by self-assembling of bifunctional thiol reagents on the nanoparticle (NP) surface via dative thiol-gold bond yielding a carboxylic acid functionalized surface. Trypsin was either attached directly via hydrophobic and ionic interactions onto the citrate stabilized GNPs or immobilized via EDC/NHS bioconjugation onto the carboxylic functionalized GNPs, respectively. The amount of bound trypsin was quantified by measuring the absorbance at 280 nm. The activity of bound enzyme and its Michaelis Menten kinetic parameter K{sub m} and v{sub max} were measured by the standard chromogenic substrate N{sub {alpha}}-Benzoyl-DL-arginine 4-nitroanilide hydrochloride (BApNA). Finally, digestion of a standard protein mixture with the trypsin-conjugated NPs followed by analysis with

  20. Bioconjugation of trypsin onto gold nanoparticles: Effect of surface chemistry on bioactivity

    International Nuclear Information System (INIS)

    Highlights: ► Size and spacer affect bioactivity of nanoparticulate trypsin reactor. ► Increase of GNP's size increases activity of bound trypsin. ► Increase of spacer length increases amount and activity of immobilized enzyme by factor 6. ► Decrease of digestion time up to less than 1 h when trypsin immobilized onto GNPs. ► Reduced auto-digestion compared to trypsin in-solution. - Abstract: The systematic study of activity, long-time stability and auto-digestion of trypsin immobilized onto gold nanoparticles (GNPs) is described in this paper and compared to trypsin in-solution. Thereby, the influence of GNP's size and immobilization chemistry by various linkers differing in lipophilicity/hydrophilicity and spacer lengths was investigated with regard to the bioactivity of the conjugated enzyme. GNPs with different sizes were prepared by reduction and simultaneous stabilization with trisodium citrate and characterized by UV/vis spectra, dynamic light scattering (DLS), ζ-potential measurements and transmission electron microscopy (TEM). GNPs were derivatized by self-assembling of bifunctional thiol reagents on the nanoparticle (NP) surface via dative thiol-gold bond yielding a carboxylic acid functionalized surface. Trypsin was either attached directly via hydrophobic and ionic interactions onto the citrate stabilized GNPs or immobilized via EDC/NHS bioconjugation onto the carboxylic functionalized GNPs, respectively. The amount of bound trypsin was quantified by measuring the absorbance at 280 nm. The activity of bound enzyme and its Michaelis Menten kinetic parameter Km and vmax were measured by the standard chromogenic substrate Nα-Benzoyl-DL-arginine 4-nitroanilide hydrochloride (BApNA). Finally, digestion of a standard protein mixture with the trypsin-conjugated NPs followed by analysis with LC–ESI-MS and successful MASCOT search demonstrated the applicability of the new heterogenous nano-structured biocatalyst. It could be shown that the amount of

  1. Bioconjugated lanthanide luminescent helicates as multilabels for lab-on-a-chip detection of cancer biomarkers.

    Science.gov (United States)

    Fernández-Moreira, Vanesa; Song, Bo; Sivagnanam, Venkataragavalu; Chauvin, Anne-Sophie; Vandevyver, Caroline D B; Gijs, Martin; Hemmilä, Ilkka; Lehr, Hans-Anton; Bünzli, Jean-Claude G

    2010-01-01

    The lanthanide binuclear helicate [Eu(2)(L(C2(CO(2)H)))(3)] is coupled to avidin to yield a luminescent bioconjugate EuB1 (Q = 9.3%, tau((5)D(0)) = 2.17 ms). MALDI/TOF mass spectrometry confirms the covalent binding of the Eu chelate and UV-visible spectroscopy allows one to determine a luminophore/protein ratio equal to 3.2. Bio-affinity assays involving the recognition of a mucin-like protein expressed on human breast cancer MCF-7 cells by a biotinylated monoclonal antibody 5D10 to which EuB1 is attached via avidin-biotin coupling demonstrate that (i) avidin activity is little affected by the coupling reaction and (ii) detection limits obtained by time-resolved (TR) luminescence with EuB1 and a commercial Eu-avidin conjugate are one order of magnitude lower than those of an organic conjugate (FITC-streptavidin). In the second part of the paper, conditions for growing MCF-7 cells in 100-200 microm wide microchannels engraved in PDMS are established; we demonstrate that EuB1 can be applied as effectively on this lab-on-a-chip device for the detection of tumour-associated antigens as on MCF-7 cells grown in normal culture vials. In order to exploit the versatility of the ligand used for self-assembling [Ln(2)(L(C2(CO(2)H)))(3)] helicates, which sensitizes the luminescence of both Eu(III) and Tb(III) ions, a dual on-chip assay is proposed in which estrogen receptors (ERs) and human epidermal growth factor receptors (Her2/neu) can be simultaneously detected on human breast cancer tissue sections. The Ln helicates are coupled to two secondary antibodies: ERs are visualized by red-emitting EuB4 using goat anti-mouse IgG and Her2/neu receptors by green-emitting TbB5 using goat anti-rabbit IgG. The fact that the assay is more than 6 times faster and requires 5 times less reactants than conventional immunohistochemical assays provides essential advantages over conventional immunohistochemistry for future clinical biomarker detection. PMID:20024180

  2. Protein expression profile of HT-29 human colon cancer cells after treatment with a cytotoxic daunorubicin-GnRH-III derivative bioconjugate.

    Directory of Open Access Journals (Sweden)

    Verena Natalie Schreier

    Full Text Available Targeted delivery of chemotherapeutic agents is a new approach for the treatment of cancer, which provides increased selectivity and decreased systemic toxicity. We have recently developed a promising drug delivery system, in which the anticancer drug daunorubicin (Dau was attached via oxime bond to a gonadotropin-releasing hormone-III (GnRH-III derivative used as a targeting moiety (Glp-His-Trp-Lys(Ac-His-Asp-Trp-Lys(Da  = Aoa-Pro-Gly-NH2; Glp = pyroglutamic acid, Ac = acetyl; Aoa = aminooxyacetyl. This bioconjugate exerted in vitro cytostatic/cytotoxic effect on human breast, prostate and colon cancer cells, as well as significant in vivo tumor growth inhibitory effect on colon carcinoma bearing mice. In our previous studies, H-Lys(Dau = Aoa-OH was identified as the smallest metabolite produced in the presence of rat liver lysosomal homogenate, which was able to bind to DNA in vitro. To get a deeper insight into the mechanism of action of the bioconjugate, changes in the protein expression profile of HT-29 human colon cancer cells after treatment with the bioconjugate or free daunorubicin were investigated by mass spectrometry-based proteomics. Our results indicate that several metabolism-related proteins, molecular chaperons and proteins involved in signaling are differently expressed after targeted chemotherapeutic treatment, leading to the conclusion that the bioconjugate exerts its cytotoxic action by interfering with multiple intracellular processes.

  3. Room temperature continuous wave operation of quantum cascade lasers with 12.5% wall plug efficiency

    International Nuclear Information System (INIS)

    An InP based quantum cascade laser heterostructure emitting at 4.6 μm was grown with gas-source molecular beam epitaxy. The wafer was processed into a conventional double-channel ridge waveguide geometry with ridge widths of 19.7 and 10.6 μm without semi-insulating InP regrowth. An uncoated, narrow ridge device with a 4.8 mm cavity length was epilayer down bonded to a diamond submount and exhibits 2.5 W maximum output power with a wall plug efficiency of 12.5% at room temperature in continuous wave operation

  4. Small- and large-signal modeling of InP HBTs in transferred-substrate technology

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas; Kraemer, Tomas; Weimann, Nils; Schnieder, Frank; Krozer, Viktor; Heinrich, Wolfgang

    In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a...

  5. An InP HBT sub-harmonic mixer for E-band wireless communication

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Krozer, Viktor

    This paper reports on a novel balanced HBT subharmonic mixer (SHM) for E-band wireless communication. An LO spiral type Marchand balun is integrated with the SHM. The SHM has been fabricated in a InP double heterojunction bipolar transistor (DHBT) circuit-oriented technology with fT /fmax = 180GHz...

  6. Status and future directions of InP solar cell research

    Science.gov (United States)

    Jain, R. K.; Weinberg, I.

    1992-01-01

    An overview of the current status and future directions of InP space solar cell research is provided. The scope of the paper does not allow us to discuss other recent major developments in InP cell modeling, contacts, and characterization, or developments in other solar cell materials. Solar cells made from InP and related materials are not expected to be used in the near future for terrestrial applications, but significant Air-Mass1.5 (AM1.5) cell efficiencies are given for comparison. This paper deals with the developments in single-junction cells, multijunction tandem cells, and space flight testing, including radiation effects. Concentrator InP solar cells are also discussed, since they offer the possibility of simultaneous thermal and current injection annealing. These cells also promise cost effectiveness and the concentrator elements may provide cells with extra protection from space radiation. The concluding section addresses the steps to be taken in the future and provides guidelines for further research and development.

  7. Embossed Bragg Gratings Based on Organically Modified Silane Waveguides in InP.

    Science.gov (United States)

    Liu, J; Lam, Y L; Chan, Y C; Zhou, Y; Ooi, B S; Tan, G; Yao, J

    2000-09-20

    Considering the large variety of applications for optical glass waveguide gratings, the effective production method of embossing for micropatterning, and the unique advantages of InP-based materials, we expect that hybridization of embossed optical glass waveguide gratings and InP substrates will inevitably lead to new applications in integrated optics. We present our preliminary results of research toward the development of solgel-derived glass waveguide gratings made by embossing on InP. Theoretically, the dependence of the stop-band FWHM and transmission contrast of the grating filter on the grating length, and the relationship between the Bragg grating's reflective wavelength and the dopant concentration in the solgel waveguide, are obtained. Experimentally, using organically modified silane, we solve the problem of mismatching of SiO(2) and InP, and successfully fabricate an embossed glass grating with a second-order Bragg reflection wavelength of 1580 nm and a FWHM of 0.7 nm fabricated upon a solgel waveguide on an InP substrate. PMID:18350088

  8. X-ray diffraction analysis of multilayer porous InP(001) structure

    Czech Academy of Sciences Publication Activity Database

    Lomov, A. A.; Punegov, V. I.; Vasil'ev, A. L.; Nohavica, Dušan; Gladkov, Petar; Kartsev, A. A.; Novikov, D. V.

    2010-01-01

    Roč. 55, č. 2 (2010), s. 182-190. ISSN 1063-7745 Institutional research plan: CEZ:AV0Z20670512 Keywords : silicon layers * INP Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.644, year: 2010

  9. An InP HBT sub-harmonic mixer for E-band wireless communication

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Krozer, Viktor

    2010-01-01

    This paper reports on a novel balanced HBT subharmonic mixer (SHM) for E-band wireless communication. An LO spiral type Marchand balun is integrated with the SHM. The SHM has been fabricated in a InP double heterojunction bipolar transistor (DHBT) circuit-oriented technology with fT /fmax = 180GHz...

  10. Patterning poly(maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) copolymer bioconjugates for controlled release of drugs.

    Science.gov (United States)

    Nita, Loredana E; Chiriac, Aurica P; Mititelu-Tartau, Liliana; Stoleru, Elena; Doroftei, Florica; Diaconu, Alina

    2015-09-30

    Owing to the special characteristics and abilities polymeric networks have received special interest for a range of biomedical applications especially for drug delivery systems. This study was devoted to preparation of new polymeric compounds based on maleic anhydride and 3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane copolymer (poly maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) (PMAU) patterned as a network for bioconjugation and tested as drug carrier systems. The PMAU copolymer was improved in its functionality by opening the maleic anhydride ring with different amounts of erythritol, which is free of side effects in regular use and a multifunctional compound, and also confers antioxidant character for the new compounds. The new polymeric matrices were loaded with acetaminophen, codeine and their fixed dose combinations. The investigation demonstrated the capability of the new structures to be used as polymer networks for linking bioactive compounds and to perform controlled delivery. The physico-chemical investigations--Fourier transform infrared spectroscopy (FTIR) spectra, contact angle, zeta potential (ZP - z, PMAU and its derivatives samples loaded with medicines present decreased values of zeta potential attesting the bioconjugate formation and as well their stability), and hydrodynamic radius, near infrared chemical imaging evaluation (new specific bands being registered for bio-conjugate with acetaminophen around of 1150-1200 nm and 1700 nm, and also between 1150 and 1200 nm in case of the codeine bio-conjugate), scanning electron microscopy (SEM) studies, X-ray diffraction analysis--evidenced the formation of the bioconjugates in relation to the chemical composition of the polymer matrices, while in vitro release study and in vivo tests confirm the capacity for drug delivery of the prepared bioactive systems. PMID:26220652

  11. Controlled ultraviolet resonance energy transfer between bovine serum albumin donors and cadmium sulfide quantum dots acceptors

    Science.gov (United States)

    Ghali, Mohsen; El-Kemary, Maged; Ramadan, Mahmoud

    2015-08-01

    We report on Förester resonance nergy transfer (FRET) within a bioconjugated system composed of cadmium sulfide (CdS) quantum dots (QDs) and transport protein bovine serum albumin (BSA). The optical properties of these two elements of the bioconjugate were exploited to produce FRET in the ultraviolet (UV) region with a maximum efficiency of 22% from BSA donors to QD acceptors. In contrast to previous studies, which were limited to FRET in the visible light, we used 2.6 nm CdS QDs because they emit light with a shorter wavelength (∼370 nm) that facilitates the UV-FRET process. UV-FRET was controlled by tuning the spectral overlap between BSA and CdS QDs.

  12. 19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact

    OpenAIRE

    Yin, Xingtian; Battaglia, Corsin; Lin, Yongjing; Chen, Kevin; Hettick, Mark; Zheng, Maxwell; Chen, Cheng-Ying; Kiriya, Daisuke; Javey, Ali

    2014-01-01

    We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO2 deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-w...

  13. Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters

    Directory of Open Access Journals (Sweden)

    R. E. Mamouri

    2015-12-01

    Full Text Available We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN and ice nucleating particle (INP number concentrations can be estimated. We show that height profiles of number concentrations of aerosol particles with radius > 50 nm (APC50, reservoir of favorable CCN and with radius > 250 nm (APC250, reservoir of favorable INP, as well as profiles of the aerosol particle surface area concentration (ASC, used in INP parameterization can be retrieved from lidar-derived aerosol extinction coefficients (AEC with relative uncertainties of a factor of around 2 (APC50, and of about 25–50 % (APC250, ASC. Of key importance is the potential of polarization lidar to identify mineral dust particles and to distinguish and separate the aerosol properties of basic aerosol types such as mineral dust and continental pollution (haze, smoke. We investigate the relationship between AEC and APC50, APC250, and ASC for the main lidar wavelengths of 355, 532 and 1064 nm and main aerosol types (dust, pollution, marine. Our study is based on multiyear Aerosol Robotic Network (AERONET photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures of continental pollution, mineral dust, and marine aerosol. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple relationship between APC50 and the CCN-reservoir particles (APCCCN and published INP parameterization schemes (with APC250 and ASC as input we finally compute APCCCN and INP concentration profiles. We apply the full methodology to a lidar observation of a heavy dust outbreak crossing Cyprus with dust up to 8 km height and to a case during which anthropogenic pollution dominated.

  14. Tuning the Lattice Parameter of InxZnyP for Highly Luminescent Lattice-Matched Core/Shell Quantum Dots.

    Science.gov (United States)

    Pietra, Francesca; De Trizio, Luca; Hoekstra, Anne W; Renaud, Nicolas; Prato, Mirko; Grozema, Ferdinand C; Baesjou, Patrick J; Koole, Rolf; Manna, Liberato; Houtepen, Arjan J

    2016-04-26

    Colloidal quantum dots (QDs) show great promise as LED phosphors due to their tunable narrow-band emission and ability to produce high-quality white light. Currently, the most suitable QDs for lighting applications are based on cadmium, which presents a toxicity problem for consumer applications. The most promising cadmium-free candidate QDs are based on InP, but their quality lags much behind that of cadmium based QDs. This is not only because the synthesis of InP QDs is more challenging than that of Cd-based QDs, but also because the large lattice parameter of InP makes it difficult to grow an epitaxial, defect-free shell on top of such material. Here, we propose a viable approach to overcome this problem by alloying InP nanocrystals with Zn(2+) ions, which enables the synthesis of InxZnyP alloy QDs having lattice constant that can be tuned from 5.93 Å (pure InP QDs) down to 5.39 Å by simply varying the concentration of the Zn precursor. This lattice engineering allows for subsequent strain-free, epitaxial growth of a ZnSezS1-z shell with lattice parameters matching that of the core. We demonstrate, for a wide range of core and shell compositions (i.e., varying x, y, and z), that the photoluminescence quantum yield is maximal (up to 60%) when lattice mismatch is minimal. PMID:27065247

  15. Click-generated triazole based ferrocene-carbohydrate bioconjugates: A highly selective multisignalling probe for Cu(II) ions

    Indian Academy of Sciences (India)

    Arunabha Thakur; Sinjinee Sardar; Sundargopal Ghosh

    2012-11-01

    Two Cu2+-specific colorimetric sensors, based on ferrocene-carbohydrate bioconjugates, 2, C46H56O20N6Fe and 3, C28H33O10N3Fe were designed and synthesized in good yields. Both the compounds, 2 and 3, behave as very selective and sensitive chromogenic and electrochemical chemosensor for Cu2+ ion in aqueous environment (CH3CN/H2O (2:8, /). The analytical detection limit (ADL) for receptor 2 was 7.5 × 10−7 M. The considerable changes in their absorption spectra of 2 and 3 are accompanied by the appearance of a new low energy (LE) peak at 630 nm (2: = 1600 M-1 cm-1 and 3: 822 M-1 cm-1). This is further accompanied by a strong colour change from yellow to dark green that allows the prospective for `naked eye’ detection of Cu2+ ion.

  16. Synthesis and characterization of dual-functionalized core-shell fluorescent microspheres for bioconjugation and cellular delivery.

    Directory of Open Access Journals (Sweden)

    Jonathan M Behrendt

    Full Text Available The efficient transport of micron-sized beads into cells, via a non-endocytosis mediated mechanism, has only recently been described. As such there is considerable scope for optimization and exploitation of this procedure to enable imaging and sensing applications to be realized. Herein, we report the design, synthesis and characterization of fluorescent microsphere-based cellular delivery agents that can also carry biological cargoes. These core-shell polymer microspheres possess two distinct chemical environments; the core is hydrophobic and can be labeled with fluorescent dye, to permit visual tracking of the microsphere during and after cellular delivery, whilst the outer shell renders the external surfaces of the microspheres hydrophilic, thus facilitating both bioconjugation and cellular compatibility. Cross-linked core particles were prepared in a dispersion polymerization reaction employing styrene, divinylbenzene and a thiol-functionalized co-monomer. These core particles were then shelled in a seeded emulsion polymerization reaction, employing styrene, divinylbenzene and methacrylic acid, to generate orthogonally functionalized core-shell microspheres which were internally labeled via the core thiol moieties through reaction with a thiol reactive dye (DY630-maleimide. Following internal labeling, bioconjugation of green fluorescent protein (GFP to their carboxyl-functionalized surfaces was successfully accomplished using standard coupling protocols. The resultant dual-labeled microspheres were visualized by both of the fully resolvable fluorescence emissions of their cores (DY630 and shells (GFP. In vitro cellular uptake of these microspheres by HeLa cells was demonstrated conventionally by fluorescence-based flow cytometry, whilst MTT assays demonstrated that 92% of HeLa cells remained viable after uptake. Due to their size and surface functionalities, these far-red-labeled microspheres are ideal candidates for in vitro, cellular

  17. Voltammetric Study and Determination of Phenylephrine Hydrochloride at INP-Nafion-Modified CPE Sensor Employing Differential Pulse Voltammetry

    Directory of Open Access Journals (Sweden)

    Zeinab Pourghobadi

    2014-03-01

    Full Text Available In this study, describes the voltammetric oxidation and determination of phenylephrine (PHE hydrochloride at a new chemically modified electrode. Iron nanoparticle (INPs was dispersed in Nafion solution to obtain a INP-Nafion-modified CPE for the voltammetric analysis of PHE .The electrochemical behaviour of PHE on INP-Nafion-modified CPE was studied, using cyclic voltammetry as a diagnostic technique. The effects of amount of INPs-Nafion dispersion, pH, and scan rate on the response of modified electrode for the oxidation of PHE were investigated. Using differential pulse voltammetry (DPV, the modified electrode indicated a dynamic linear range for quantitative determination of PHE in the range of 5 μM−130 μM, and the detection limit was estimated to be 0.76 μM. The method was developed for the determination of PHE in pharmaceutical samples with satisfactory results.

  18. Model of defect formation in annealed undoped and Fe-doped liquid encapsulated Czochralski InP

    OpenAIRE

    S Fung; Beling, CD; Youwen, Zhao; Xiaoliang, Xu; Min, Gong; Niefeng, Sun; Tongnian, Sun; Xudong, Chen; Ronggui, Zhang; Silin, Liu

    1998-01-01

    Infrared absorption spectroscopy measurements indicate high concentration of hydrogen indium vacancy complex VInH4 in undoped and Fe-doped liquid encapsulated Czochralski (LEC) InP. Annealed undoped and Fe-doped semi-insulating (SI) InP are studied by room temperature Hall effect measurement and photocurrent spectroscopy. The results show that a mid gap donor defect and some shallow intrinsic defects are formed by high temperature annealing. This mid gap defect is shown to be phosphorus antis...

  19. Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters

    Science.gov (United States)

    Mamouri, Rodanthi-Elisavet; Ansmann, Albert

    2016-05-01

    We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of particle number concentrations n50, dry considering dry aerosol particles with radius > 50 nm (reservoir of CCN in the case of marine and continental non-desert aerosols), n100, dry (particles with dry radius > 100 nm, reservoir of desert dust CCN), and of n250, dry (particles with dry radius > 250 nm, reservoir of favorable INP), as well as profiles of the particle surface area concentration sdry (used in INP parameterizations) can be retrieved from lidar-derived aerosol extinction coefficients σ with relative uncertainties of a factor of 1.5-2 in the case of n50, dry and n100, dry and of about 25-50 % in the case of n250, dry and sdry. Of key importance is the potential of polarization lidar to distinguish and separate the optical properties of desert aerosols from non-desert aerosol such as continental and marine particles. We investigate the relationship between σ, measured at ambient atmospheric conditions, and n50, dry for marine and continental aerosols, n100, dry for desert dust particles, and n250, dry and sdry for three aerosol types (desert, non-desert continental, marine) and for the main lidar wavelengths of 355, 532, and 1064 nm. Our study is based on multiyear Aerosol Robotic Network (AERONET) photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple CCN parameterization (with n50, dry or n100, dry as input) and available INP parameterization schemes (with n250, dry and sdry as input) we finally compute

  20. Future coordinated researches by ANL (USA), INP AS RUz and INP NNC RKaz on the nuclear reactions and astrophysics

    International Nuclear Information System (INIS)

    should be peripheral and one-step mechanism of the particle transfer should dominate. In addition, the first excited states of outgoing 12C or 16O particles lie rather high (4.44 and 6.05 MeV respectively), so the interference of their excited states with the low lying states of final nuclei B will not take place. The reactions A(3He,d)B (ε3He→d+p=5.49 MeV) and A(t,d)B (ε3H→d+n=6.257 MeV) can be used also, but the energy of proton separation is somewhat more. The alpha transfer reactions A(6Li,d)B, A(7Li,t)B and A(7Be,3He)B is supposed to be used for obtaining ANCs B→ A+α because the projectiles are nuclei with weakly bound α - cluster. The possibility of implementation such experiments on ATLAS (ANL, USA) and U-150M (INP, Kazakhstan) accelerators is discussed

  1. On the usage of classical nucleation theory in quantification of the impact of bacterial INP on weather and climate

    Science.gov (United States)

    Sahyoun, Maher; Wex, Heike; Gosewinkel, Ulrich; Šantl-Temkiv, Tina; Nielsen, Niels W.; Finster, Kai; Sørensen, Jens H.; Stratmann, Frank; Korsholm, Ulrik S.

    2016-08-01

    Bacterial ice-nucleating particles (INP) are present in the atmosphere and efficient in heterogeneous ice-nucleation at temperatures up to -2 °C in mixed-phase clouds. However, due to their low emission rates, their climatic impact was considered insignificant in previous modeling studies. In view of uncertainties about the actual atmospheric emission rates and concentrations of bacterial INP, it is important to re-investigate the threshold fraction of cloud droplets containing bacterial INP for a pronounced effect on ice-nucleation, by using a suitable parameterization that describes the ice-nucleation process by bacterial INP properly. Therefore, we compared two heterogeneous ice-nucleation rate parameterizations, denoted CH08 and HOO10 herein, both of which are based on classical-nucleation-theory and measurements, and use similar equations, but different parameters, to an empirical parameterization, denoted HAR13 herein, which considers implicitly the number of bacterial INP. All parameterizations were used to calculate the ice-nucleation probability offline. HAR13 and HOO10 were implemented and tested in a one-dimensional version of a weather-forecast-model in two meteorological cases. Ice-nucleation-probabilities based on HAR13 and CH08 were similar, in spite of their different derivation, and were higher than those based on HOO10. This study shows the importance of the method of parameterization and of the input variable, number of bacterial INP, for accurately assessing their role in meteorological and climatic processes.

  2. Fabrication and optical characterization of large scale membrane containing InP/AlGaInP quantum dots

    Science.gov (United States)

    Niederbracht, H.; Hargart, F.; Schwartz, M.; Koroknay, E.; Kessler, C. A.; Jetter, M.; Michler, P.

    2015-06-01

    Single-photon sources with a high extraction efficiency are a prerequisite for applications in quantum communication and quantum computation schemes. One promising approach is the fabrication of a quantum dot containing membrane structure in combination with a solid immersion lens and a metal mirror. We have fabricated an 80 nm thin semiconductor membrane with incorporated InP quantum dots in an AlGaInP double hetero barrier via complete substrate removal. In addition, a gold layer was deposited on one side of the membrane acting as a mirror. The optical characterization shows in detail that the unique properties of the quantum dots are preserved in the membrane structure.

  3. Site-Controlled Growth of Single InP QDs

    International Nuclear Information System (INIS)

    The MOVPE growth of InP/GaInP quantum dots (QDs) on GaAs substrate “defects” formed by a focused beam of Ga+ ions is studied. It is shown that ordered arrays of QDs with a density of 0.25 (μm)−2 can be obtained in the InP/GaInP system. It is demonstrated that effective luminescence can be obtained by using two QD sheets separated by a GaAs/GaInP buffer layer

  4. Downstream etching of GaAs and InP using molecular chlorine and chlorine radicals

    International Nuclear Information System (INIS)

    The temperature dependent etching of GaAs and InP using both molecular and remote plasma activated Cl2 and HCl is examined. GaAs etches nearly three times faster in a remotely generated Cl2 plasma than in a molecular Cl2 environment with plasma off. The temperature dependance from room temperature to 250 degrees C is similar for both cases. Significant etch rates of GaAs are observed for HCl remotely generated plasma even at room temperature (∼1000 Angstrom/min). Although the etch rate for InP below 150 degrees C is quite low for either Cl2 or HCl, the relatively fast, temperature independent etch rate above this temperature is comparable to that of GaAs. The results are compared to RIE and a thermodynamic model

  5. X-ray diffraction analysis of multilayer porous InP(001) structure

    International Nuclear Information System (INIS)

    Multilayer structures composed of four porous bilayers have been studied by high-resolution X-ray diffraction using synchrotron radiation, and the photoluminescence of these structures has been investigated at 4 K. The porous structures were formed by anodic oxidation of InP(001) substrates in aqueous HCl solution. The structural parameters of the sublayers were varied by changing the electrochemical etching mode (potentiostatic/galvanostatic). The X-ray scattering intensity maps near the InP 004 reflection are obtained. A model for scattering from such systems is proposed based on the statistical dynamical diffraction theory. Theoretical scattering maps have been fitted to the experimental ones. It is shown that a mathematical analysis of the scattering intensity maps makes it possible to determine the structural parameters of sublayers. The reconstructed parameters (thickness, strain, and porosity of sublayers and the shape and arrangement of pores) are in satisfactory agreement with the scanning electron microscopy data.

  6. Some features of solar cells with vertical p-n junctions in InP

    International Nuclear Information System (INIS)

    Numeral calculation performed and graphic distribution were given of not equilibrium charge carriers along depth in p- and n-regions of p-n junction in InP at different significance of surface recombination velocity of not equilibrium carriers and at maximum significance of absorption recombination coefficient . At this case is considered lighted surface of diode by radiation falling parallel plane of p-n junction. The optimum size of individual diodes in solar cells battery were defined for achievement of maximum separate coefficient of not equilibrium charge carriers of p-n junctions. The region of spectral sensibilities for solar cells battery with the vertical p-n junctions on InP are estimated and discussed some way of it expanding

  7. Evolution of InP surfaces under low fluence pulsed UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Musaev, O.R. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)], E-mail: musaevo@umkc.edu; Kwon, O.S.; Wrobel, J.M.; Zhu, D.-M.; Kruger, M.B. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)

    2008-07-15

    An InP wafer was irradiated in air by a series of UV pulses from a nitrogen laser with fluences of 120 mJ/cm{sup 2} and 80 mJ/cm{sup 2}. These fluences are below the single-pulse ablation threshold of InP. Over the studied region the distribution of the radiation intensity was uniform. The number of pulses varied from 50 to 6000. The evolution of the surface morphology and structure was characterized by atomic force microscopy, optical microscopy and Raman spectroscopy. The relationship between mound size and the number of pulses starts out following a power law, but saturates for a sufficiently high number of pulses. The crossover point is a function of fluence. A similar relation exists for the surface roughness. Raman spectroscopic investigations showed little change in local crystalline structure of the processed surface layer.

  8. Growth of semiconductor alloy InGaPBi on InP by molecular beam epitaxy

    International Nuclear Information System (INIS)

    We report the first successful growth of InGaPBi single crystals on InP substrate with Bi concentration far beyond the doping level by gas source molecular beam epitaxy. The InGaPBi thin films reveal excellent surface and structural qualities, making it a promising new III–V compound family member for heterostructures. The strain can be tuned between tensile and compressive by adjusting Ga and Bi compositions. The maximum achieved Bi concentration is 2.2 ± 0.4% confirmed by Rutherford backscattering spectroscopy. Room temperature photoluminescence shows strong and broad light emission at energy levels much smaller than the InP bandgap. (paper)

  9. Effects of Be doping on InP nanowire growth mechanisms

    International Nuclear Information System (INIS)

    Be-doped InP nanowires were grown by the gold-assisted vapour-liquid-solid mechanism in a gas source molecular beam epitaxy system. The InP nanowire length versus diameter [L(D)] dependence revealed an unexpected transition with increasing Be dopant concentration. At Be dopant concentration below ∼1018 cm−3, nanowires exhibited the usual inverse L(D) relationship, indicating a diffusion-limited growth regime. However, as dopant concentration increased, the nanowire growth rate was suppressed for small diameters, resulting in an unusual L(D) dependence that increased before saturating in height at about 400 nm. The cause of this may be a change in the droplet chemical potential, introducing a barrier to island nucleation. We propose a model accounting for the limitations of diffusion length and monolayer nucleation to explain this behaviour.

  10. Chemically prepared well-ordered InP(0 0 1) surfaces

    Science.gov (United States)

    Tereshchenko, O. E.; Paget, D.; Chiaradia, P.; Placidi, E.; Bonnet, J. E.; Wiame, F.; Taleb-Ibrahimi, A.

    2006-08-01

    In the present work HCl-isopropanol treated and vacuum annealed InP(0 0 1) surfaces were studied by means of low-energy electron diffraction (LEED), soft X-ray photoemission (SXPS), and reflectance anisotropy (RAS) spectroscopies. The treatment removes the natural oxide and leaves on the surface a physisorbed overlayer containing InCl x and phosphorus. Annealing at 230 °C induces desorption of InCl x overlayer and reveals a P-rich (2 × 1) surface. Subsequent annealing at higher temperature induces In-rich (2 × 4) surface. The structural properties of chemically prepared InP(0 0 1) surfaces were found to be similar to those obtained by decapping of As/P-capped epitaxial layers.

  11. Effect of substrate orientation on the catalyst-free growth of InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Mattila, M [Micro and Nanotechnology Laboratory, Helsinki University of Technology, Micronova, PO Box 3500, FIN-02015 TKK (Finland); Hakkarainen, T [Micro and Nanotechnology Laboratory, Helsinki University of Technology, Micronova, PO Box 3500, FIN-02015 TKK (Finland); Jiang, H [VTT Biotechnology, PO Box 1000, FIN-02044 VTT (Finland); Kauppinen, E I [VTT Biotechnology, PO Box 1000, FIN-02044 VTT (Finland); Lipsanen, H [Micro and Nanotechnology Laboratory, Helsinki University of Technology, Micronova, PO Box 3500, FIN-02015 TKK (Finland)

    2007-04-18

    We report the fabrication of self-catalysed InP nanowires on (111)B, (111)A, (110), and (001) InP substrates. Indium droplets, deposited in situ using metalorganic vapour phase epitaxy, are used as seeds for nanowire growth. The preferential nanowire growth direction is always <111> on (111)B (111)A, and (110) oriented substrates. On (111)A substrates some initial growth in the [111]A direction is observed before kinking into one of the available <111>B directions. The nanowires are optically active at room temperature. On (001) substrates no nanowire growth off the substrate is observed. However, growth still takes place in the two possible equivalent <111>B azimuthal directions.

  12. Heat treatment effect on p type Zn doped InP substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dhouib, A.; Maloumbi, B.; Martinez, C. and others

    1987-10-01

    During the process of elaboration of n/sup +//p InP photodiodes for solar energy conversion, we have observed that the 700 C sulfur diffusion into Zn doped InP substrates strongly modifies the electrical and photoelectrical properties of these substrates. A simple annealing at the same temperature produces nearly equivalent effects. The most relevant modification is a strong, depth independent hole density increase (more than one order of magnitude). A degradation of the photoelectrical parameters: diffusion length L and carrier lifetime tau has also been detected near the surface of the heat treated substrates. The deep traps measured from deep level transient spectroscopy (DLTS) are not typical of the heat treatment.

  13. Relaxation processes under microindentation of InP crystals subjected to scratching deformation

    International Nuclear Information System (INIS)

    The elastic strain relaxation was estimated by the use of the method of acoustic emission signal registration under microindentation. The coefficient K for the estimation of relaxation degree under unloading was introduced. The preliminary strain degree of InP single crystals and accordingly the internal stresses were varied by the scratching method as well as by the testing temperature (293-723 K) and storage of predeformed crystals at room temperature. It was shown that the relaxation processes are determined by the stress defect structure state and are the predeformation temperature function. These processes are tightly related to the internal strain stress, characterizing the start state of InP single crystals. (authors)

  14. Hydrogen sensors based on electrophoretically deposited Pd nanoparticles onto InP

    OpenAIRE

    Piksová Kateřina; Grym Jan; Procházková Olga; Yatskiv Roman

    2011-01-01

    Abstract Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed. We demonstrate that the substrate pre-deposition treatment and the deposition conditions can extensively influence the morphology of the deposited palladium nanoparticle films. Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning. More...

  15. X-ray photoemission investigation of excimer laser induced etching of InP

    International Nuclear Information System (INIS)

    ArF excimer laser induced etching of InP in various etch gases (HBr, HCl, Cl2) is discussed with regard to its spatial resolution capability. X-ray photoemission spectra and large-area etch rate measurements published before lead to fundamental understanding and interpretation of the characteristics of etched test structures. HBr and HCl require gas phase photodissociation. Cl2, in contrast, has the advantage to react spontaneously

  16. High-efficiency ultrasmall polarization converter in InP membrane.

    Science.gov (United States)

    Pello, Josselin; van der Tol, Jos; Keyvaninia, Shahram; van Veldhoven, René; Ambrosius, Huub; Roelkens, Gunther; Smit, Meint

    2012-09-01

    An ultrasmall (polarization converter in InP membrane is fabricated and characterized. The device relies on the beating between the two eigenmodes of chemically etched triangular waveguides. Measurements show a very high polarization conversion efficiency of >99% with insertion losses of <-1.2  dB at a wavelength of 1.53 μm. Furthermore, our design is found to be broadband and tolerant to dimension variations. PMID:22940999

  17. Design and fabrication of an InP arrayed waveguide grating for monolithic PICs

    Institute of Scientific and Technical Information of China (English)

    Pan Pan; An Junming; Wang Liangliang; Wu Yuanda; Wang Yue; Hu Xiongwei

    2012-01-01

    A 10-channel,200 GHz channel spacing InP arrayed waveguide grating was designed,and the deep ridge waveguide design makes it polarization independent.Under the technologies of molecular beam epitaxy,lithography,and induced coupler plasma etching,the chip was fabricated in our laboratory.The test results show that the insertion loss is about 8 dB,and the crosstalk is less than-17 dB.

  18. Phosphorous vacancy nearest-neighbor hopping involved instabilities in InP MIS capacitors

    International Nuclear Information System (INIS)

    The drain current of an InP MISFET is often observed to decrease as a function of time after the application of a positive gate bias which involves an accumulation of electrons in the channel. Various models have been proposed for this drain current drift (DCD) phenomena. In this study, the authors have employed variable-temperature bias-stress measurements of InP MIS capacitors in order to determine the dominant DCD mechanisms from an analysis of the activation energy of the flatband shift. There are two advantages inherent in bias-stress measurements of MIS capacitors compared to DCD measurements of InP MISFETs. First, fabrication of the MIS capacitor requires very few processing steps compared to that of a MISFET so that the interface chemistry can be precisely controlled and the electrical instabilities may be correlated to the interface chemistry. Two distinct activation energies at 45meV and 1.2eV were obtained from variable-temperature bias-stress measurements over a temperature range of 100 - 350K. The 45meV activation energy dominates the flatband shift at low temperatures and is consistent with thermally activated tunneling of electrons from the InP conduction band into a discrete trap in the native oxide. The 1.2eV activation energy is that predicted for phosphorus vacancy nearest-neighbor hopping (PVNNH) in which the channel electrons are captured by shallow acceptors which are created by the hopping of an In atom into a phosphorus vacancy. The estimated fraction of the flatband shift in these particular samples at room temperature due to PVNNH is approximately 20%

  19. Stability investigation for InP DHBT mm‐wave power amplifier

    DEFF Research Database (Denmark)

    Yan, Lei; Johansen, Tom Keinicke; Kammersgaard, Jacob

    2013-01-01

    In this article, we discuss stability issues for mm‐wave monolithic integrated power amplifiers using InP double heterojunction bipolar transistor (DHBT) technology targeting E‐band applications at 71–76 GHz and 81–86 GHz. Different stability detection methods based on the classical two‐port K‐Δs...... Periodicals, Inc. Int J RF and Microwave CAE 23: 662–674, 2013....

  20. Schottky Barriers Based on Nanoporous InP with Gold Nanoparticles.

    Science.gov (United States)

    Barlas, Tetyana; Dmitruk, Mykola; Kotova, Nataliya; Mamykin, Sergii

    2016-12-01

    Schottky barrier structures based on nanoporous InP with inclusion of Au nanoparticles and evaporated semitransparent Au film have been made. The spectra of short-circuit photocurrent in the visible range and current-voltage characteristics have been measured. Prepared structures are characterized by increased photocurrent due to the microrelief interface and surface plasmon excitation in gold nanoparticles as well as increased surface recombination especially in the short wavelength region. PMID:27075341

  1. Observation of edge-facets in InP crystals grown by LEC method

    Science.gov (United States)

    Shibata, Masatomo; Sasaki, Yukio; Inada, Tomoki; Kuma, Shoji

    1990-05-01

    The growth of edge-facets on InP crystals has been investigated using microscopy. The solid/liquid interface in the region of edge-facets was found to have a knife-edged shape, while that of a region without facets had a smooth shape. The irregular patterns of edge-facets point to instability in the growth at the periphery of a crystal, and this instability is found to be related to the generation of twins.

  2. Site-specific bioconjugation of a murine dihydrofolate reductase enzyme by copper(I-catalyzed azide-alkyne cycloaddition with retained activity.

    Directory of Open Access Journals (Sweden)

    Sung In Lim

    Full Text Available Cu(I-catalyzed azide-alkyne cycloaddition (CuAAC is an efficient reaction linking an azido and an alkynyl group in the presence of copper catalyst. Incorporation of a non-natural amino acid (NAA containing either an azido or an alkynyl group into a protein allows site-specific bioconjugation in mild conditions via CuAAC. Despite its great potential, bioconjugation of an enzyme has been hampered by several issues including low yield, poor solubility of a ligand, and protein structural/functional perturbation by CuAAC components. In the present study, we incorporated an alkyne-bearing NAA into an enzyme, murine dihydrofolate reductase (mDHFR, in high cell density cultivation of Escherichia coli, and performed CuAAC conjugation with fluorescent azide dyes to evaluate enzyme compatibility of various CuAAC conditions comprising combination of commercially available Cu(I-chelating ligands and reductants. The condensed culture improves the protein yield 19-fold based on the same amount of non-natural amino acid, and the enzyme incubation under the optimized reaction condition did not lead to any activity loss but allowed a fast and high-yield bioconjugation. Using the established conditions, a biotin-azide spacer was efficiently conjugated to mDHFR with retained activity leading to the site-specific immobilization of the biotin-conjugated mDHFR on a streptavidin-coated plate. These results demonstrate that the combination of reactive non-natural amino acid incorporation and the optimized CuAAC can be used to bioconjugate enzymes with retained enzymatic activity.

  3. The electrochemical capacitance-voltage characterization of InP based p-i-n structures

    Science.gov (United States)

    Wang, Li-wei; Lu, Yi-dan; Xu, Jin-tong; Li, Xiang-yang

    2013-09-01

    Electrochemical Capacitance-Voltage (EC-V) profiling is currently one of the most often used methods for majority carrier concentration depth profiling of semiconductors. The experiments of EC-V profiling on InP based structures were conducted by Wafer Profiler CVP21, and there are two problems in the experiments of InP based p-i-n structures : a)the experimental results of EC-V profiling of i layer were not in line with the theoretically data after the EC-V profiling of p layer, which can be measured within the error range; b) The measurements of etching depth were not very accurate. In this paper, we made comparative experiments on InP based n-i-n structures, and find out a method to deal with the first problem: firstly etch p layer before EC-V profiling, so we can gain a relatively accurate result of EC-V profiling of i layer. Besides, use back contacts instead of front contacts to do the EC-V profiling according to the instruction book of the Wafer Profiler CVP21. Then the author tried to infer the reason that results in the first problem theoretically. Meanwhile we can calibrate the etching depth through Profile-system and Scanning Probe Microscope (SPM). And there are two possible reasons which result in the second problem: the defects of the semiconductors and the electrolyte we used to etch the semiconductors.

  4. The X-ray response of InP: Part B, synchrotron radiation measurements

    CERN Document Server

    Owens, A; Bavdaz, M; Brammertz, G; Dubecky, F; Gostilo, V; Gryaznov, D; Haack, N; Krumrey, M; Loupilov, A

    2002-01-01

    In this, the second part of a detailed study into the X-ray response of InP, we present results of a series of X-ray measurements on a 3.142 mm sup 2 x180 mu m thick semi-insulating InP detector at the BESSY II and HASYLAB synchrotron radiation research facilities. Photon metrology was carried out at energies ranging from 8 to 100 keV. Additional measurements were made using radioactive and fluorescent target sources. At -60 deg. C, under full-area illumination, the FWHM energy resolution was 2.4 keV at 5.9 keV rising to 8.5 keV at 59.54 keV. Under pencil-beam illumination, the measured resolutions were generally less, being 2 keV FWHM at 8 keV rising approximately linearly to 5 keV at 100 keV. Analysis of the energy resolution function indicates that poor charge transport presently limit the performance of InP detectors and specifically hole trapping. This is borne out by the observed low-energy tailing of the pulse height spectra at intermediate and high energies. At very low count rates, it was found that ...

  5. Structure of InP single crystals irradiated with reactor neutrons

    International Nuclear Information System (INIS)

    The structural characteristics of InP single crystals have been investigated depending on the radiation effects produced by fast neutrons and the full spectrum of the reactor neutrons and subsequent heat treatment procedures. The lattice parameter of InP single crystals decreases under neutron irradiation as opposed to other III-V semiconductor compounds. Fast neutrons make the main contribution to the change of the lattice parameter. A thermal neutron component initiates the formation of Sn atoms in the material, but does not influence the change of the lattice parameter significantly. Heat treatment of the irradiated samples up to 600 deg. C causes annealing of the radiation defects and recovery of the lattice parameter. With increasing neutron fluences, the lattice parameter becomes even higher than before irradiation. The data analysis proves the following assumption: anti-site defects PIn mainly contribute to the lattice parameter decrease during neutron irradiation of InP. In this case, anti-site imperfections produce an effect similar to that of vacancy defects

  6. Ab-Initio Calculations of Electronic Properties of InP and GaP

    Science.gov (United States)

    Malozovsky, Y.; Franklin, L.; Ekuma, E. C.; Zhao, G. L.; Bagayoko, D.

    2013-06-01

    We present results from ab-initio, self-consistent local density approximation (LDA) calculations of electronic and related properties of zinc blende indium phosphide (InP) and gallium phosphide (GaP). We employed a LDA potential and implemented the linear combination of atomic orbitals (LCAO) formalism. This implementation followed the Bagayoko, Zhao and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). This method searches for the optimal basis set that yields the minima of the occupied energies. This search entails increases of the size of the basis set and the related modifications of angular symmetry and of radial orbitals. Our calculated, direct band gap of 1.398 eV (1.40 eV), at the Γ point, is in excellent agreement with experimental values, for InP, and our preliminary result for the indirect gap of GaP is 2.135 eV, from the Γ to X high symmetry points. We have also calculated electron and hole effective masses for both InP and GaP. These calculated properties also agree with experimental findings. We conclude that the BZW-EF method could be employed in calculations of electronic properties of high-Tc superconducting materials to explain their complex properties.

  7. Emission variation in infrared (CdSeTe)/ZnS quantum dots conjugated to antibodies

    International Nuclear Information System (INIS)

    The paper presents the photoluminescence (PL) and Raman scattering investigations of infrared CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) in nonconjugated states and after the conjugation to the anti-papilloma virus antibodies (Ab). The Raman scattering study has shown that the CdSeTe core includes two layers with different material compositions such as: CdSe0.5Te0.5 and CdSe0.7Te0.3. PL spectra of nonconjugated CdSeTe/ZnS QDs are characterized by two Gaussian shape PL bands related to exciton emission in the CdSeTe core and in intermediate layer at the core/shell interface. PL spectra of bioconjugated QDs have changed essentially: the main PL band related to the core emission shifts into high energy and become asymmetric. The energy diagram of double core/shell CdSeTe/ZnS QDs has been analyzed to explain the PL spectrum of nonconjugated QDs and its transformation at the bioconjugation to the papiloma virus antibodies. It is shown that the PL spectrum transformation in bioconjugated QDs can be a powerful technique for biology and medicine

  8. Emission variation in infrared (CdSeTe)/ZnS quantum dots conjugated to antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo Gómez, J.A. [UPIITA – Instituto Politécnico Nacional, México D. F. 07320, México (Mexico); Casas Espinola, J.L., E-mail: jlcasas@esfm.ipn.mx [ESFM – Instituto Politécnico Nacional, México D. F. 07738, México (Mexico); Douda, J. [UPIITA – Instituto Politécnico Nacional, México D. F. 07320, México (Mexico)

    2014-11-15

    The paper presents the photoluminescence (PL) and Raman scattering investigations of infrared CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) in nonconjugated states and after the conjugation to the anti-papilloma virus antibodies (Ab). The Raman scattering study has shown that the CdSeTe core includes two layers with different material compositions such as: CdSe{sub 0.5}Te{sub 0.5} and CdSe{sub 0.7}Te{sub 0.3}. PL spectra of nonconjugated CdSeTe/ZnS QDs are characterized by two Gaussian shape PL bands related to exciton emission in the CdSeTe core and in intermediate layer at the core/shell interface. PL spectra of bioconjugated QDs have changed essentially: the main PL band related to the core emission shifts into high energy and become asymmetric. The energy diagram of double core/shell CdSeTe/ZnS QDs has been analyzed to explain the PL spectrum of nonconjugated QDs and its transformation at the bioconjugation to the papiloma virus antibodies. It is shown that the PL spectrum transformation in bioconjugated QDs can be a powerful technique for biology and medicine.

  9. Synthesis and characterization of antigenic influenza A M2e protein peptide-poly(acrylic) acid bioconjugate and determination of toxicity in vitro.

    Science.gov (United States)

    Kilinc, Yasemin Budama; Akdeste, Zeynep Mustafaeva; Koc, Rabia Cakir; Bagirova, Melahat; Allahverdiyev, Adil

    2014-01-01

    The influenza A virus is a critical public health problem that causes epidemics and pandemics, and occurs widely all over the world. Various vaccines against the virus have not provided a solution to the problem. Different approaches, particularly M2e peptide-based vaccines, are available for developing universal vaccines against influenza A. However, it is important to select a suitable carrier to obtain an effective vaccine. Accordingly, studies on the usage of various carriers are ongoing. Particularly, polymer-based carriers have gained importance due to both drug delivery and adjuvant effects. Therefore, bioconjugate of the M2e protein peptide from the influenza A virus covalent bonded with poly(acrylic) acid was synthesized in our study for the first time. The characterization was performed using size-exclusion chromatography and fluorescence spectroscopy; subsequently, it was found that the bioconjugate of the examined lower doses (0.05 and 0.5 mg/ml) have no toxic effects on human cell lines. These results suggest that, in the future, the poly(acrylic) acid bioconjugate of the M2e peptide should be studied in vivo for universal vaccine development against the influenza A virus. PMID:25482080

  10. CdSe/ZnS quantum dots with interface states as biosensors

    Science.gov (United States)

    Torchynska, T. V.

    2011-10-01

    The paper presents the brief review of published results as well as the original study of photoluminescence (PL) and Raman scattering of core-shell CdSe/ZnS quantum dots (QDs) with radiative interface states. First commercially available CdSe/ZnS QDs with emission at 525 nm (2.36 eV), 565 nm (2.20 eV), 605 nm (2.05 eV) and 640 nm (1.96 eV) covered by PEG polymer have been compared in nonconjugated states. PL spectra of nonconjugated QDs are characterized by a superposition of PL bands related to exciton emission in CdSe cores and to hot electron-hole emission via high energy states (2.00, 2.20, 2.37, 2.75 and 3.04 eV). The high energy states were studded using QDs of different sizes and at different temperatures. It is shown that these PL bands related to interface states. Then the CdSe/ZnS QDs with the color emission 525nm and 605 nm have been conjugated with bio-molecules - ovarian cancer (OC 125) and anti Interleukin 10 (IL-10) antibodies, respectively. It is revealed that the PL spectrum of bioconjugated QDs has changed dramatically with essential decreasing the hot electron-hole recombination flow via interface states. The variation of PL spectra at the bioconjugation is explained on the base of electrostatic interaction and re-charging of QD interface states. The Raman scattering study of nonconjugated and bioconjugated QDs has shown that mentioned antibodies are characterized by the dipole moment that provokes the surface enhance Raman scattering effect in bioconjugated QD samples as well.

  11. InP tunnel junction for InGaAs/InP tandem solar cells

    Science.gov (United States)

    Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

    1995-10-01

    Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

  12. InP based QCL in MBE production machine

    Science.gov (United States)

    Garcia, Michel; Vermersch, Francois Julien; Marcadet, Xavier; Bansropun, Shailendra; Carras, Mathieu; Wilk, Arnaud; Chaix, Christine; Sirtori, Carlo

    2006-02-01

    Quantum Cascade Lasers (QCL), emitting between 5 and 9 μm, have been realised with a view to achieving QCLs fabrication on a production scale. The growth of the structures was carried out in a multi-wafer RIBER 49 system (13 x 2" platen), and the processing sequence involved an Inductively Coupled Plasma (ICP) step for homogeneity and reproducibility purposes. To validate the approach used, a first batch of lasers, emitting around 9μm, based on a design already published [1], has been realised. State of the art performance on these devices (J th = 4.2 kA cm -2, η = 304 mW A -1, P max = 690 mW) has been achieved. A second set of strained balanced structures, emitting around 5.4μm, has been demonstrated, working in pulsed operation at room temperature(J th = 3.9 kA cm -2, η = 362 mW A -1, P max = 420 mW).

  13. Defects in mitophagy promote redox-driven metabolic syndrome in the absence of TP53INP1.

    Science.gov (United States)

    Seillier, Marion; Pouyet, Laurent; N'Guessan, Prudence; Nollet, Marie; Capo, Florence; Guillaumond, Fabienne; Peyta, Laure; Dumas, Jean-François; Varrault, Annie; Bertrand, Gyslaine; Bonnafous, Stéphanie; Tran, Albert; Meur, Gargi; Marchetti, Piero; Ravier, Magalie A; Dalle, Stéphane; Gual, Philippe; Muller, Dany; Rutter, Guy A; Servais, Stéphane; Iovanna, Juan L; Carrier, Alice

    2015-06-01

    The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D). T2D is characterized by insulin resistance resulting from both environmental and genetic factors. A genome-wide association study (GWAS) published in 2010 identified TP53INP1 as a new T2D susceptibility locus, but a pathological mechanism was not identified. In this work, we show that mice lacking TP53INP1 are prone to redox-driven obesity and insulin resistance. Furthermore, we demonstrate that the reactive oxygen species increase in TP53INP1-deficient cells results from accumulation of defective mitochondria associated with impaired PINK/PARKIN mitophagy. This chronic oxidative stress also favors accumulation of lipid droplets. Taken together, our data provide evidence that the GWAS-identified TP53INP1 gene prevents metabolic syndrome, through a mechanism involving prevention of oxidative stress by mitochondrial homeostasis regulation. In conclusion, this study highlights TP53INP1 as a molecular regulator of redox-driven metabolic syndrome and provides a new preclinical mouse model for metabolic syndrome clinical research. PMID:25828351

  14. Enhanced Biosensor Platforms for Detecting the Atherosclerotic Biomarker VCAM1 Based on Bioconjugation with Uniformly Oriented VCAM1-Targeting Nanobodies

    Directory of Open Access Journals (Sweden)

    Duy Tien Ta

    2016-07-01

    Full Text Available Surface bioconjugation of biomolecules has gained enormous attention for developing advanced biomaterials including biosensors. While conventional immobilization (by physisorption or covalent couplings using the functional groups of the endogenous amino acids usually results in surfaces with low activity, reproducibility and reusability, the application of methods that allow for a covalent and uniformly oriented coupling can circumvent these limitations. In this study, the nanobody targeting Vascular Cell Adhesion Molecule-1 (NbVCAM1, an atherosclerotic biomarker, is engineered with a C-terminal alkyne function via Expressed Protein Ligation (EPL. Conjugation of this nanobody to azidified silicon wafers and Biacore™ C1 sensor chips is achieved via Copper(I-catalyzed azide-alkyne cycloaddition (CuAAC “click” chemistry to detect VCAM1 binding via ellipsometry and surface plasmon resonance (SPR, respectively. The resulting surfaces, covered with uniformly oriented nanobodies, clearly show an increased antigen binding affinity, sensitivity, detection limit, quantitation limit and reusability as compared to surfaces prepared by random conjugation. These findings demonstrate the added value of a combined EPL and CuAAC approach as it results in strong control over the surface orientation of the nanobodies and an improved detecting power of their targets—a must for the development of advanced miniaturized, multi-biomarker biosensor platforms.

  15. Controlled Release of Damascone from Poly(styrene-co-maleic anhydride-based Bioconjugates in Functional Perfumery

    Directory of Open Access Journals (Sweden)

    Andreas Herrmann

    2013-02-01

    Full Text Available Poly(styrene-co-maleic anhydrides were modified with poly(propylene oxide (PO-co-ethylene oxide (EO side chains (Jeffamine® with different EO/PO molar ratios, varying between 0.11 and 3.60. These copolymers were then further functionalized with a β-mercapto ketone of δ-damascone. The obtained poly(maleic acid monoamide-based β-mercapto ketones were then studied as delivery systems for the controlled release of δ-damascone by retro 1,4-addition. The release of δ-damascone, a volatile, bioactive molecule of the family of rose ketones, was studied by dynamic headspace analysis above a cotton surface after deposition of a cationic surfactant containing fabric softening formulation, as a function of the ethylene oxide (EO/propylene oxide (PO molar ratio of the grafted copolymer side chains. The polarity of the EO/PO side chain influenced the release efficiency of the damascone in a typical fabric softening application. PO-rich copolymers and the corresponding poly(styrene-co-maleic anhydride without Jeffamine® side chains were found to be less efficient for the desired fragrance release than the corresponding bioconjugate with a EO/PO ratio of 3.60 in the side chain. This copolymer conjugate seemed to represent a suitable balance between hydrophilicity and hydrophobicity to favor the release of the δ-damascone and to improve the deposition of the conjugate from an aqueous environment onto a cotton surface.

  16. Enhanced Biosensor Platforms for Detecting the Atherosclerotic Biomarker VCAM1 Based on Bioconjugation with Uniformly Oriented VCAM1-Targeting Nanobodies.

    Science.gov (United States)

    Ta, Duy Tien; Guedens, Wanda; Vranken, Tom; Vanschoenbeek, Katrijn; Steen Redeker, Erik; Michiels, Luc; Adriaensens, Peter

    2016-01-01

    Surface bioconjugation of biomolecules has gained enormous attention for developing advanced biomaterials including biosensors. While conventional immobilization (by physisorption or covalent couplings using the functional groups of the endogenous amino acids) usually results in surfaces with low activity, reproducibility and reusability, the application of methods that allow for a covalent and uniformly oriented coupling can circumvent these limitations. In this study, the nanobody targeting Vascular Cell Adhesion Molecule-1 (NbVCAM1), an atherosclerotic biomarker, is engineered with a C-terminal alkyne function via Expressed Protein Ligation (EPL). Conjugation of this nanobody to azidified silicon wafers and Biacore™ C1 sensor chips is achieved via Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry to detect VCAM1 binding via ellipsometry and surface plasmon resonance (SPR), respectively. The resulting surfaces, covered with uniformly oriented nanobodies, clearly show an increased antigen binding affinity, sensitivity, detection limit, quantitation limit and reusability as compared to surfaces prepared by random conjugation. These findings demonstrate the added value of a combined EPL and CuAAC approach as it results in strong control over the surface orientation of the nanobodies and an improved detecting power of their targets-a must for the development of advanced miniaturized, multi-biomarker biosensor platforms. PMID:27399790

  17. Biomimetic approach to the formation of gold nanoparticle/silica core/shell structures and subsequent bioconjugation

    International Nuclear Information System (INIS)

    The encapsulation of individual nanoparticles has gained great attention as a method for both stabilizing nanoparticles and tailoring their surface properties. In particular, the encapsulation of nanoparticles with silica shells is advantageous for bioconjugation and applications to (nano)biotechnology. Herein we report a method for constructing gold nanoparticle (AuNP)/silica core/shell hybrid structures by biomimetic silicification of silicic acids. The procedure consists of surface-initiated, atom transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from AuNPs and biomimetic polycondensation of silicic acids by using poly(DMAEMA) as a synthetic counterpart for silaffins that are found in diatoms. The resulting AuNP/silica hybrids were characterized by Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy, UV-vis spectroscopy and transmission electron microscopy. In addition, the immobilization of biological ligands onto the hybrids was investigated for potential applications to biotechnology. As a model ligand, biotin was attached onto the AuNP/silica hybrids through substitution reaction and Michael addition reaction, and the attachment was confirmed by fluorescence microscopy after complexation with fluorescein-conjugated streptavidin

  18. Studies on semiconductors based on InP with sub-ps response times; Untersuchungen an auf InP basierenden Halbleitern mit sub-ps Responsezeiten

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, K.

    2007-06-28

    The present work describes investigation of new material concepts accomplished using molecular-beam-epitaxy (MBE) growth for application in ultra-fast photonic components. Nominally undoped and Be doped GaInAs/AlInAs multiple-quantumwell structures (MQW) were grown by MBE at growth temperatures down to 100 C (LT-MBE) on semi-insulating InP substrates. Crystalline, electric and optical properties of as-grown and annealed structures were investigated. Energy states near the conduction band of GaInAs determine the electrical and optical properties of LT-MQWs. The dynamics of charge carrier relaxation was studied by means of pump and probe experiments. Measurements of the differential transmission when excited by an additional cw laser and measurements utilizing two closely sequenced pump pulses support the capability of Be doped as-grown (annealed) LT GaInAs/AlInAs MQW structures for use in optical switches at switching frequencies in the 1 Tbit/s (250 Gbit/s) range. The voltage-induced change of interband transmission of InP based quantumcascade-lasers (QCL) during pulsed mode operation was analyzed by means of 8 band k.p calculations. The impacts of varying charge carrier distributions and of electrically heated samples can be neglected compared to the dominating effect of the electrical field on the interband transmission. The impact of MBE growth parameters on the interface quality of AlAsSb/ GaInAs heterostructures were determined by means of Hall measurements, temperature- and intensity-dependent PL measurements and spectral measurements of the interband- and intersubband-absorption. The impact of In segregation and Sb diffusion on the intersubband absorption was analyzed on the basis of bandstructure calculations. Intersubband transitions at wavelengths of about 1.8 {mu}m (1.55 {mu}m) were successfully achieved in MQW (coupled QW) structures. (orig.)

  19. Photoluminescence of double core/shell infrared (CdSeTe)/ZnS quantum dots conjugated to Pseudo rabies virus antibodies

    Science.gov (United States)

    Torchynska, T. V.; Casas Espinola, J. L.; Jaramillo Gómez, J. A.; Douda, J.; Gazarian, K.

    2013-06-01

    Double core CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) have been studied by photoluminescence (PL) and Raman scattering methods in the non-conjugated state and after the conjugation to the Pseudo rabies virus (PRV) antibodies. The transformation of PL spectra, stimulated by the electric charge of antibodies, has been detected for the bioconjugated QDs. Raman scattering spectra are investigated with the aim to reveal the CdSeTe core compositions. The double core QD energy diagrams were designed that help to analyze the PL spectra and their transformation at the bioconjugation. It is revealed that the interface in double core QDs has the type II quantum well character that permits to explain the near IR optical transition (1.60 eV) in the double core QDs. It is shown that the essential transformation of PL spectra is useful for the study of QD bioconjugation with specific antibodies and can be a powerful technique in early medical diagnostics.

  20. Studies of zinc-blende type MnAs thin films grown on InP(001) substrates by XRD

    Science.gov (United States)

    Oomae, H.; Irizawa, S.; Jinbo, Y.; Toyota, H.; Kambayashi, T.; Uchitomi, N.

    2013-09-01

    The detailed crystalline structure of molecular beam epitaxially grown MnAs thin films on InP(001) substrate has been investigated using high resolution X-ray diffraction techniques. Reciprocal space mapping of the MnAs/InP(001) samples indicates that the MnAs has a cubic zinc-blende (zb) structure with the epitaxial relationship zb-MnAs[110]|InP[110]. The lattice constant of zb-MnAs is ˜6.06 Å. The MnAs lattice is relaxed and is mosaic-like likely due to large lattice mismatch between the film and InP substrate. The isotropic nature of the magnetic properties supported our conjecture that the MnAs epitaxial film under study has indeed a cubic structure.

  1. Control of morphology and crystal purity of InP nanowires by variation of phosphine flux during selective area MOMBE

    International Nuclear Information System (INIS)

    We present experimental results showing how the growth rate, morphology and crystal structure of Au-catalyzed InP nanowires (NWs) fabricated by selective area metal organic molecular beam epitaxy can be tuned by the growth parameters: temperature and phosphine flux. The InP NWs with 20–65 nm diameters are grown at temperatures of 420 and 480 °C with the PH3 flow varying from 1 to 9 sccm. The NW tapering is suppressed at a higher temperature, while pure wurtzite crystal structure is preferred at higher phosphine flows. Therefore, by combining high temperature and high phosphine flux, we are able to fabricate non-tapered and stacking fault-free InP NWs with the quality that other methods rarely achieve. We also develop a model for NW growth and crystal structure which explains fairly well the observed experimental tendencies. (paper)

  2. Electronic properties of InP (001)/HfO2 (001) interface: Band offsets and oxygen dependence

    International Nuclear Information System (INIS)

    Using ab-initio methods, atomic structures and electronic properties of InP (001)/HfO2 (001) interface are studied within the framework of density functional theory. We examine the InP/HfO2 model interface electronic structures under varying oxidation conditions. The effects of indium and phosphorous concentrations on interfacial bonding, defect states, band offsets, and the thermodynamic stability at the interface are also investigated. The origin of interfacial gap states in InP (001)/HfO2 (001) interface are proposed, mainly from the P-rich oxides, which is validated by our experimental work. This highlights the importance of surface passivation prior to high-κ deposition based on the in situ spectroscopic results of atomic layer deposition of HfO2 on InP

  3. Quantitative strain mapping of InAs/InP quantum dots with 1 nm spatial resolution using dark field electron holography

    DEFF Research Database (Denmark)

    Cooper, David; Rouviere, Jean-Luc; Béché, Armand;

    2011-01-01

    The optical properties of semiconductor quantum dots are greatly influenced by their strain state. Dark field electron holography has been used to measure the strain in InAs quantum dots grown in InP with a spatial resolution of 1 nm. A strain value of 5.4%60.1% has been determined which is consi......The optical properties of semiconductor quantum dots are greatly influenced by their strain state. Dark field electron holography has been used to measure the strain in InAs quantum dots grown in InP with a spatial resolution of 1 nm. A strain value of 5.4%60.1% has been determined which...... is consistent with both measurements made by geometrical phase analysis of high angle annular dark field scanning transmission electron microscopy images and with simulations....

  4. Quantum Permanents and Quantum Hafnians

    OpenAIRE

    Jing, Naihuan; Jian ZHANG

    2015-01-01

    Analogous to the quantum general linear group, a quantum group is investigated on which the quantum determinant is shown to be equal to the quantum permanent. The quantum Hafnian is then computed by a closely related quantum permanent. Similarly the quantum Pfaffian is proved to be identical to the quantum Hafnian on the quantum algebra.

  5. Hydrogen passivation of N(+)-P and P(+)-N heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, Basab; Davis, William C.; Ringel, Steve A.; Hoffman, Richard, Jr.

    1996-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n-p and p-n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)-p and p(+)-n heteroepitaxial InP cell structures from as-grown values of 5-7 x 10(exp 14) cm(exp -3), down to 3-5 x 10(exp 12) cm(exp -3). All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. One to five analysis indicated a subsequent approximately 100 fold decrease in reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)-n structures. In addition to being passivated, dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  6. Hydrogen Passivation of N(+)P and P(+)N Heteroepitaxial InP Solar Cell Structures

    Science.gov (United States)

    Chatterjee, B.; Davis, W. C.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n(+)p and p(+)n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)p and p(+)n heteroepitaxial InP cell structures from as-grown values of 5 - 7 x 10(exp 14)/cc, down to 3 - 5 x 10(exp 12)/cc. All dopants were successfully reactivated by a 400 C, 5 minute anneal With no detectable activation of deep levels. I-V analysis indicated a subsequent approx. 100 fold decrease In reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)n structures. ln addition to being passivated,dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  7. Hydrogen sensors based on electrophoretically deposited Pd nanoparticles onto InP

    Science.gov (United States)

    Grym, Jan; Procházková, Olga; Yatskiv, Roman; Piksová, Kateřina

    2011-05-01

    Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed. We demonstrate that the substrate pre-deposition treatment and the deposition conditions can extensively influence the morphology of the deposited palladium nanoparticle films. Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning. Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

  8. Hydrogen sensors based on electrophoretically deposited Pd nanoparticles onto InP

    Directory of Open Access Journals (Sweden)

    Piksová Kateřina

    2011-01-01

    Full Text Available Abstract Electrophoretic deposition of palladium nanoparticles prepared by the reverse micelle technique onto InP substrates is addressed. We demonstrate that the substrate pre-deposition treatment and the deposition conditions can extensively influence the morphology of the deposited palladium nanoparticle films. Schottky diodes based on these films show notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi level pinning. Moreover, electrical characteristics of these diodes are exceptionally sensitive to the exposure to gas mixtures with small hydrogen content.

  9. Schottky barriers based on metal nanoparticles deposited on InP epitaxial layers

    International Nuclear Information System (INIS)

    Fabrication of high-quality Schottky barriers on InP epitaxial layers prepared by liquid-phase epitaxy from rare-earth treated melts is reported. The Schottky structures are based on metal nanoparticles and a graphite layer deposited from colloidal solutions onto epitaxial layers with varying carrier concentration. The structures have notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi-level pinning. Electrical characteristics of these diodes are shown to be extremely sensitive to the exposure of gas mixtures with small hydrogen content. (paper)

  10. Schottky barriers based on metal nanoparticles deposited on InP epitaxial layers

    Science.gov (United States)

    Grym, Jan; Yatskiv, Roman

    2013-04-01

    Fabrication of high-quality Schottky barriers on InP epitaxial layers prepared by liquid-phase epitaxy from rare-earth treated melts is reported. The Schottky structures are based on metal nanoparticles and a graphite layer deposited from colloidal solutions onto epitaxial layers with varying carrier concentration. The structures have notably high values of the barrier height and of the rectification ratio giving evidence of a small degree of the Fermi-level pinning. Electrical characteristics of these diodes are shown to be extremely sensitive to the exposure of gas mixtures with small hydrogen content.

  11. Enhanced Eshelby Twist on Thin Wurtzite InP Nanowires and Measurement of Local Crystal Rotation

    Science.gov (United States)

    Tizei, L. H. G.; Craven, A. J.; Zagonel, L. F.; Tencé, M.; Stéphan, O.; Chiaramonte, T.; Cotta, M. A.; Ugarte, D.

    2011-11-01

    We have performed a detailed study of the lattice distortions of InP wurtzite nanowires containing an axial screw dislocation. Eshelby predicted that this kind of system should show a crystal rotation due to the dislocation induced torque. We have measured the twisting rate and the dislocation Burgers vector on individual wires, revealing that nanowires with a 10-nm radius have a twist up to 100% larger than estimated from elasticity theory. The strain induced by the deformation has a Mexican-hat-like geometry, which may create a tube-like potential well for carriers.

  12. Influence of Grain Size on Electrical and Optical Properties of InP Films

    Institute of Scientific and Technical Information of China (English)

    Mustafa (O)ztas

    2008-01-01

    InP film samples were prepared by spray pyrolysis technique using aqueous solutions of lnCl3 and Na2HPO4,which were atomized with compressed air as carrier gas onto glass substrates at 500℃ with different thicknesses of the films. It is found that the resistivity of the polycrystalline films strongly depends on the grain size. It is observed that the grain size of the films increase with the decrease of the energy band gap and strain of the film.The changes observed in the energy band gap and strain related to the film grain size of the films are discussed in detail.

  13. Nuclear geophysics in space and atmospheric research at INPE/BRAZIl

    Science.gov (United States)

    Nordemann, D. J. R.; Pereira, E. B.; Marinho, E. V. A.; Sircillineto, F.

    1986-05-01

    In recent years, INPE's research in Nuclear Geophysics has developed in fields of interest to the Institute, the scientific community and the society in general. In the space research field a contribution has been made to the history of meteorite falls on our planet and its possible collision with large meteorites, which may have been the cause of important effects such as biological extinction and extraterrestrial matter gathering. In atmospheric research, spatial and temporal variations of radon measurements in the lower atmosphere permit correlations from micrometeorology to mesoscale phenomena, related to the dynamics of air masses.

  14. Nuclear geophysics in space and atmospheric reserch at INPE/BRAZIl

    International Nuclear Information System (INIS)

    During the last years, INPE's research in Nuclear Geophysics has developed in fields of interest to the Institute, the scientific community and the society in general. In the space research field it may be considered as a contribution to the history of meteorite falls in our planet or possible collision with big meteorites which may have been the cause of important effects such as biological extinction and extraterrestrial matter gathering. In the atmospheric research field, spatial and temporal variations of radon measurements in the lower atmosphere allow correlations from micrometeorology to worlwide scale through mesoscale, in the interpretation of phenomena which deal with the dynamics of air masses. (Author)

  15. Frequency stability of InP HBT over 0.2 to 220 GHz

    Science.gov (United States)

    Zhijiang, Zhou; Kun, Ren; Jun, Liu; Wei, Cheng; Haiyan, Lu; Lingling, Sun

    2015-02-01

    The frequency stabilities of InP DHBTs in a broadband over 1 to 220 GHz are investigated. A hybrid π-topology small-signal model is used to accurately capture the parasitics of devices. The model parameters are extracted from measurements analytically. The investigation results show that the excellent agreement between the measured and simulated data is obtained in the frequency range 200 MHz to 220 GHz. The dominant parameters of the π-topology model, bias conditions and emitter area have significant effects on the stability factor K. The HBT model can be unconditionally stable by reasonable selection of the proper bias condition and the physical layout of the device.

  16. InP/(Al,Ga)InP quantum dots on GaAs- and Si-substrates for single-photon generation at elevated temperatures

    OpenAIRE

    Bommer, Moritz

    2013-01-01

    This work concentrates on optical investigation on single-photon generation for applications in communications, quantum cryptography, and quantum computing. Single-photon sources for commercial devices require robustness in their working conditions, e.g. temperature, pressure, etc. as well as high output rates and emission directionality. From the many possibilities of generating single-photons like single-atoms, parametric down-conversion, nitrogen vacancy centers in diamond etc., InP quantu...

  17. Growth and characterization of InP/In0.48Ga0.52P quantum dots optimized for single-photon emission

    International Nuclear Information System (INIS)

    In this work the growth of self-assembled InP/InGaP quantum dots, as well as their optical and structural properties are presented and discussed. The QDs were grown on In0.48Ga0.52P, lattice matched to GaAs. Self-assembled InP quantum dots are grown using gas-source molecular beam epitaxy over a wide range of InP deposition rates, using an ultra-low growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/μm2 is realized. The resulting isolated InP quantum dots are individually characterized without the need for lithographical patterning and masks on the substrate. Both excitonic and biexcitonic emissions are observed from single dots, appearing as doublets with a fine-structure splitting of 320 μeV. Hanbury Brown-Twiss correlation measurements for the excitonic emission under cw excitation show anti-bunching behavior with an autocorrelation value of g(2)(0)=0.2. This system is applicable as a single-photon source for applications such as quantum cryptography. The formation of well-ordered chains of InP quantum dots on GaAs (001) substrates by using self-organized In0.48Ga0.52P surface undulations as a template is also demonstrated. The ordering requires neither stacked layers of quantum dots nor substrate misorientation. The structures are investigated by polarization-dependent photoluminescence together with transmission electron microscopy. Luminescence from the In0.48Ga0.52P matrix is polarized in one crystallographic direction due to anisotropic strain arising from a lateral compositional modulation. The photoluminescence measurements show enhanced linear polarization in the alignment direction of quantum dots. A polarization degree of 66% is observed. The optical anisotropy is achieved with a straightforward heterostructure, requiring only a single layer of QDs.

  18. Bioconjugated gold nanoparticles enhance cellular uptake: A proof of concept study for siRNA delivery in prostate cancer cells.

    Science.gov (United States)

    Guo, Jianfeng; O'Driscoll, Caitriona M; Holmes, Justin D; Rahme, Kamil

    2016-07-25

    The chemistry of gold nanoparticles (AuNPs) facilitates surface modifications and thus these bioengineered NPs have been investigated as a means of delivering a variety of therapeutic cargos to treat cancer. In this study we have developed AuNPs conjugated with targeting ligands to enhance cell-specific uptake in prostate cancer cells, with a purpose of providing efficient non-viral gene delivery systems in the treatment of prostate cancer. As a consequence, two novel AuNPs were synthesised namely AuNPs-PEG-Tf (negatively charged AuNPs with the transferrin targeting ligands) and AuNPs-PEI-FA (positively charged AuNPs with the folate-receptor targeting ligands). Both bioconjugated AuNPs demonstrated low cytotoxicity in prostate cancer cells. The attachment of the targeting ligand Tf to AuNPs successfully achieved receptor-mediated cellular uptake in PC-3 cells, a prostate cancer cell line highly expressing Tf receptors. The AuNPs-PEI-FA effectively complexed small interfering RNA (siRNA) through electrostatic interaction. At the cellular level the AuNPs-PEI-FA specifically delivered siRNA into LNCaP cells, a prostate cancer cell line overexpressing prostate specific membrane antigen (PSMA, exhibits a hydrolase enzymic activity with a folate substrate). Following endolysosomal escape the AuNPs-PEI-FA.siRNA formulation produced enhanced endogenous gene silencing compared to the non-targeted formulation. Our results suggest both formulations have potential as non-viral gene delivery vectors in the treatment of prostate cancer. PMID:27188645

  19. Growth of SiO2 on InP substrate by liquid phase deposition

    International Nuclear Information System (INIS)

    We have grown silicon dioxide (SiO2) on indium phosphorous (InP) substrate by liquid phase deposition (LPD) method. With inserting InP wafer in the treatment solution composed of SiO2 saturated hydrofluorosilicic acid (H2SiF6), 0.1 M boric acid (H3BO3) and 1.74 M diluted hydrochloric acid (HCl), the maximum deposition rate and refractive index for the as-grown LPD-SiO2 film were about 187.5 A/h and 1.495 under the constant growth temperature of 40 deg. C. The secondary ion mass spectroscope (SIMS) and energy dispersive X-ray (EDX) confirmed that the elements of silicon, oxygen, and chloride were found in the as-grown LPD-SiO2 film. On the other hand, the effects of treatment solution incorporated with the hydrogen peroxide (H2O2) that can regulate the concentration of OH- ion were also shown in this article. The experimental results represented that the deposition rate decreases with increasing the concentration of hydrogen peroxide due to the reduced concentration of SiO2 saturated H2SiF6 in treatment solution.

  20. Annealing of irradiated n+p InP buried homojunctions

    Science.gov (United States)

    Walters, Robert J.; Summers, Geoffrey P.; Timmons, M. L.; Venkatasubramanian, R.; Hancock, J. A.; Hills, J. S.

    1994-01-01

    At the last SPRAT conference, the Naval Research Laboratory (NRL) presented results from two experiments. One studied n+p diffused junction (DJ) InP solar cells, and the other studied n+p shallow homojunction (SHJ) InP mesa diodes grown by metalorganic chemical vapor deposition (MOCVD). The former work showed that a DJ solar cell in which the maximum power P(sub max) had been degraded by nearly 80 percent under irradiation recovered completely under short circuit illumination at 450K. The recovery was accompanied by the removal of all but one of the radiation-induced defect levels. The latter work, on the other hand, showed that the radiation-induced defects in the SHJ diodes did not anneal until the temperature reached 650K. These results suggest that an irradiated DJ solar cell, under illumination, will anneal at a temperature 200K lower than an irradiated SHJ cell. This is an unexpected result considering the similarity of the devices. The goal of the present research is to explain this different behavior. This paper investigates two points which arose from the previous studies. The first point is that the DJ cells were annealed under illumination while the SHJ diodes were annealed without bias. The second point investigated here is that the emitters of the DJ and SHJ devices were significantly different.

  1. The effect of process conditions on the performance of epitaxial InP solar cells

    Science.gov (United States)

    Borrego, J. M.; Ghandi, S. K.

    1991-01-01

    Indium phosphide solar cells have a higher resistance to electron irradiation than Si or GaAs cells of comparable junction depth. As a result, there is much interest in the use of this material for space applications. Cells of this material were made in bulk InP by a number of techniques, including ion implantation, direct diffusion in sealed ampoules, and by open tube diffusion. However, it is generally considered that the epitaxial approach will be superior to all of these techniques. The epitaxy of InP is considerably more difficult than that of gallium arsenide, for a number of reasons. Perhaps the most important is the fact that the native oxides of Indium are extremely difficult to remove, as compared to that of Gallium. In addition, thermal treatments for the desorption of these oxides often result in the formation of phosphorus vacancies and free indium on the surface. Thus, inadequate sample preparation before epitaxy, poor reactor cleaning procedures, or poor transition procedures between the growth of successive layers, all give rise to trap phenomena and to high interface recombination velocities. Moreover, the lifetime of the grown material is dominated by the occurrence of native defects, so that it is a strong function of growth parameters. These problems are of special interest to the fabrication of solar cells, where long life-time, combined with the absence of traps, is highly desirable. A study of this problem is described using a non-invasive diagnostic technique which was developed.

  2. Structural, electronic, and magnetic properties of Mn-Doped InP nanowire

    Science.gov (United States)

    Srivastava, Pankaj; Kumar, Avaneesh; Jaiswal, Neeraj K.

    2016-04-01

    In the present work, we investigate structural stability, electronic and magnetic properties of InP nanowire (NW) oriented along (111) direction and doped with Mn using first-principles calculations. Structural analysis revealed that incorporation of Mn atom in NW geometry results in strong reconstructions of surface atoms relative to core atoms. For single Mn-doped NW, partially filled d orbital of Mn atom results in magnetic semiconducting behavior due to non-degenerate electronic band-gap (∼0.1 eV). We have further considered the effect of Mn-Mn coupling on the electronic/magnetic properties of InP NW. Anti-ferromagnetic coupling state is observed as most favorable state based on total energy calculations. A half-metallic ferromagnetic coupling is also observed in case of Mn-pair doped at sub-surface of NW. The present results predict that the system doped with Mn pair between surface and core region are energetically more favorable than others.

  3. Investigation on optical absorption properties of electrochemically formed porous InP using photoelectric conversion devices

    International Nuclear Information System (INIS)

    We investigated the optical absorption properties of InP porous structures formed by the electrochemical process using photoelectric conversion (PC) devices formed on p–n junction substrates. The photocurrent measurements revealed that the current from PC devices changed in response to the incident light power and the thickness of the top layer on the p–n interface. Since the photocarriers contributing to the observed photocurrents are excited by the photons reaching the p–n interface through the top layer, the photocurrents give us information on the optical absorption properties of the top layer. The photocurrents observed on a porous device with a porous structure in the top layer were lower than that of a non-porous device, indicating that the absorption properties of InP were enhanced after the formation of porous structures. This phenomenon can be explained in terms of absorption coefficient, α, increased by the light scattering and the sub-bandgap absorption in the porous layer.

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

    International Nuclear Information System (INIS)

    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 ηp=14.4±0.4% and ηp=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. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot

    DEFF Research Database (Denmark)

    Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal; Patriarche, Gilles; Harmand, Jean-Christophe; Akopian, Nika; Zwiller, Val

    2016-01-01

    unprecedented potential to be controlled with atomic layer accuracy without random alloying. We show for the first time that crystal phase quantum dots are a source of pure single-photons and cascaded photon-pairs from type II transitions with excellent optical properties in terms of intensity and line width......We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer....... We notice that the emission spectra consist often of two peaks close in energy, which we explain with a comprehensive theory showing that the symmetry of the system plays a crucial role for the hole levels forming hybridized orbitals. Our results state that crystal phase quantum dots have promising...

  6. Quantum dots in biomedical applications: advances and challenges

    Science.gov (United States)

    Cinteza, Ludmila Otilia

    2010-09-01

    In the past two decades, nanotechnology has made great progress in generating novel materials with superior properties. Quantum dots (QDs) are an example of such materials. With unique optical properties, they have proven to be useful in a wide range of applications in life sciences, especially as a better alternative to overcome the shortcomings of conventional fluorophores. Current progress in the synthesis of biocompatible QDs allows for the possibility of producing a large variety of semiconductor nanocrystals in terms of size, surface functionality, bioconjugation, and targeting facilities. Strategies to enhance the water-dispersibility and biocompatibility of these nanoparticles have been developed, involving various encapsulation techniques and surface functionalization. The major obstacle in the clinical use of QDs remains their toxicity, and the systematic investigation on harmful effects of QDs both to humans and to the environment has become critical. Many examples of the experimental use of QDs prove their far-reaching potential for the study of intracellular processes at the molecular level, high resolution cellular imaging, and in vivo observation of cell trafficking. Biosensing methods based on QD bioconjugates proved to be successful in rapid detection of pathogens, and significant improvements are expected in early cancer diagnostic, non-conventional therapy of cancer and neurodegenerative diseases.

  7. Quantum Erasure: Quantum Interference Revisited

    OpenAIRE

    Walborn, Stephen P.; Cunha, Marcelo O Terra; Pádua, Sebastião; Monken, Carlos H.

    2005-01-01

    Recent experiments in quantum optics have shed light on the foundations of quantum physics. Quantum erasers - modified quantum interference experiments - show that quantum entanglement is responsible for the complementarity principle.

  8. Submicron InP DHBT technology for high-speed high-swing mixed-signal ICs

    DEFF Research Database (Denmark)

    Godin, Jean; Nodjiadjim, V.; Riet, Muriel; Berdaguer, Pierre; Drisse, O.; Derouin, Eric; Konczykowska, Agnieszka; Moulu, Jean; Dupuy, Jean-Yves; Jorge, Fellipe; Gentner, Jean-Louis; Krozer, Viktor; Johansen, Tom Keinicke; Scavennec, Andre

    2008-01-01

    We report on the development of a submicron InP DHBT technology, optimized for the fabrication of 50-GHz-clock mixed signal ICs. In-depth study of device geometry and structure has allowed to get the needed performances and yield. Special attention has been paid to critical thermal behavior...

  9. Enrichment of InP crystal surface by indium as a result of selective material evaporation under pulsed laser irradiation

    International Nuclear Information System (INIS)

    Laser irradiation flux threshold density under which local melting-like changes on InP, GaAs and InAs crystals surface were established. Conclusion was made that changes are due to compounds decomposition under beam heating of surface to temperatures lower than compound melting point

  10. High detection performance of particle detectors based on SI InP doped with Ti and Zn

    Czech Academy of Sciences Publication Activity Database

    Gorodynskyy, Vladyslav; Yatskiv, Roman; Žďánský, Karel; Pekárek, Ladislav

    2008-01-01

    Roč. 55, č. 5 (2008), s. 2785-2788. ISSN 0018-9499 R&D Projects: GA AV ČR KAN400670651 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z20670512 Keywords : radiation detection * InP * crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.518, year: 2008

  11. Electronic properties of pure and p-type doped hexagonal sheets and zigzag nanoribbons of InP

    International Nuclear Information System (INIS)

    Unlike graphene, a hexagonal InP sheet (HInPS) cannot be obtained by mechanical exfoliation from the native bulk InP, which crystallizes in the zinc blende structure under ambient conditions. However, by ab initio density functional theory calculations we found that a slightly buckled HInPS is stable both in pristine form and when doped with Zn atoms; the same occurred for hydrogen-passivated zigzag InP nanoribbons (ZInPNRs), quasi-one-dimensional versions of the quasi-two-dimensional material. We investigated the electronic properties of both nanostructures, in the latter case also in the presence of an external transverse electric field, and the results are compared with those of hypothetical planar HInPS and ZInPNRs. The band gaps of planar ZInPNRs were found to be tunable by the choice of strength of this field, and to show an asymmetric behavior under weak electric fields, by which the gap can either be increased or decreased depending on their direction; however, this effect is absent from slightly buckled ZInPNRs. The binding energies of the acceptor impurity states of Zn-doped HInPS and ZInPNRs were found to be similar and much larger than that of Zn-doped bulk InP. These latter findings show that the reduction of the dimensionality of these materials limits the presence of free carriers. (paper)

  12. A high conversion-gain Q-band InP DHBT subharmonic mixer using LO frequency doubler

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor;

    2008-01-01

    (DHBT) technology using coplanar waveguide structures. To the best of our knowledge, this is the first demonstration of an SHM using InP DHBT technology at millimeter-wave frequencies. The measured results demonstrate a conversion gain of 10.3 dB at 45 GHz with an LO power of only 1 mW. The fundamental...

  13. Hydrogen passivation of n+p and p+n heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, B.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    High-efficiency, heteroepitaxial (HE) InP solar cells, grown on GaAs, Si or Ge substrates, are desirable for their mechanically strong, light-weight and radiation-hard properties. However, dislocations, caused by lattice mismatch, currently limit the performance of the HE cells. This occurs through shunting paths across the active photovoltaic junction and by the formation of deep levels. In previous work we have demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of dislocations in specially designed HE InP test structures. In this work, we present the first report of successful hydrogen passivation in actual InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in HE n+n InP cell structures from as-grown values of approximately 10(exp 15)/cm(exp -3), down to 1-2 x 10(exp 13)/cm(exp -3). The deep levels in the p-type base region of the cell structure match those of our earlier p-type test structures, which were attributed to dislocations or related point defect complexes. All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. I-V analysis indicated a subsequent approximately 10 fold decrease in reverse leakage current at -1 volt reverse bias, and no change in the forward biased series resistance of the cell structure which indicates complete reactivation of the n+ emitter. Furthermore, electrochemical C-V profiling indicates greatly enhanced passivation depth, and hence hydrogen diffusion, for heteroepitaxial structures when compared with identically processed homoepitaxial n+p InP structures. An analysis of hydrogen diffusion in dislocated InP will be discussed, along with comparisons of passivation effectiveness for n+p versus p+n heteroepitaxial cell configurations. Preliminary hydrogen

  14. Modulational instability of electrostatic acoustic waves in an electron-hole semiconductor quantum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yunliang, E-mail: ylwang@ustb.edu.cn; Lü, Xiaoxia [Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)

    2014-02-15

    The modulational instability of quantum electrostatic acoustic waves in electron-hole quantum semiconductor plasmas is investigated using the quantum hydrodynamic model, from which a modified nonlinear Schrödinger equation with damping effects is derived using the reductive perturbation method. Here, we consider the combined effects of quantum recoil, quantum degenerate pressures, as well as the exchange-correlation effect standing for the electrons (holes) spin. The modulational instability for different semiconductors (GaAs, GaSb, and InP) is discussed. The collision between electron (hole) and phonon is also investigated. The permitted maximum time for modulational instability and the damping features of quantum envelope solitary wave are all determined by the collision. The approximate solitary solution with damping effects is presented in weak collision limit. The damping properties were discussed by numerical method.

  15. Modulational instability of electrostatic acoustic waves in an electron-hole semiconductor quantum plasma

    International Nuclear Information System (INIS)

    The modulational instability of quantum electrostatic acoustic waves in electron-hole quantum semiconductor plasmas is investigated using the quantum hydrodynamic model, from which a modified nonlinear Schrödinger equation with damping effects is derived using the reductive perturbation method. Here, we consider the combined effects of quantum recoil, quantum degenerate pressures, as well as the exchange-correlation effect standing for the electrons (holes) spin. The modulational instability for different semiconductors (GaAs, GaSb, and InP) is discussed. The collision between electron (hole) and phonon is also investigated. The permitted maximum time for modulational instability and the damping features of quantum envelope solitary wave are all determined by the collision. The approximate solitary solution with damping effects is presented in weak collision limit. The damping properties were discussed by numerical method

  16. AES, EELS and TRIM simulation method study of InP(100 subjected to Ar+, He+ and H+ ions bombardment.

    Directory of Open Access Journals (Sweden)

    Abidri B.

    2012-06-01

    Full Text Available Auger Electron Spectroscopy (AES and Electron Energy Loss Spectroscopy (EELS have been performed in order to investigate the InP(100 surface subjected to ions bombardment. The InP(100 surface is always contaminated by carbon and oxygen revealed by C-KLL and O-KLL AES spectra recorded just after introduction of the sample in the UHV spectrometer chamber. The usually cleaning process of the surface is the bombardment by argon ions. However, even at low energy of ions beam (300 eV indium clusters and phosphorus vacancies are usually formed on the surface. The aim of our study is to compare the behaviour of the surface when submitted to He+ or H+ ions bombardment. The helium ions accelerated at 500V voltage and for 45 mn allow removing contaminants but induces damaged and no stoichiometric surface. The proton ions were accelerated at low energy of 500 eV to bombard the InP surface at room temperature. The proton ions broke the In-P chemical bonds to induce the formation of In metal islands. Such a chemical reactivity between hydrogen and phosphorus led to form chemical species such as PH and PH3, which desorbed from the surface. The chemical susceptibly and the small size of H+ advantaged their diffusion into bulk. Since the experimental methods alone were not able to give us with accuracy the disturbed depth of the target by these ions. We associate to the AES and EELS spectroscopies, the TRIM (Transport and Range of Ions in Matter simulation method in order to show the mechanism of interaction between Ar+, He+ or H+ ions and InP and determine the disturbed depth of the target by argon, helium or proton ions.

  17. AES, EELS and TRIM simulation method study of InP(100) subjected to Ar+, He+ and H+ ions bombardment.

    Science.gov (United States)

    Ghaffour, M.; Abdellaoui, A.; Bouslama, M.; Ouerdane, A.; Abidri, B.

    2012-06-01

    Auger Electron Spectroscopy (AES) and Electron Energy Loss Spectroscopy (EELS) have been performed in order to investigate the InP(100) surface subjected to ions bombardment. The InP(100) surface is always contaminated by carbon and oxygen revealed by C-KLL and O-KLL AES spectra recorded just after introduction of the sample in the UHV spectrometer chamber. The usually cleaning process of the surface is the bombardment by argon ions. However, even at low energy of ions beam (300 eV) indium clusters and phosphorus vacancies are usually formed on the surface. The aim of our study is to compare the behaviour of the surface when submitted to He+ or H+ ions bombardment. The helium ions accelerated at 500V voltage and for 45 mn allow removing contaminants but induces damaged and no stoichiometric surface. The proton ions were accelerated at low energy of 500 eV to bombard the InP surface at room temperature. The proton ions broke the In-P chemical bonds to induce the formation of In metal islands. Such a chemical reactivity between hydrogen and phosphorus led to form chemical species such as PH and PH3, which desorbed from the surface. The chemical susceptibly and the small size of H+ advantaged their diffusion into bulk. Since the experimental methods alone were not able to give us with accuracy the disturbed depth of the target by these ions. We associate to the AES and EELS spectroscopies, the TRIM (Transport and Range of Ions in Matter) simulation method in order to show the mechanism of interaction between Ar+, He+ or H+ ions and InP and determine the disturbed depth of the target by argon, helium or proton ions.

  18. Fabrication and optical properties of type-II InP/InAs nanowire/quantum-dot heterostructures

    International Nuclear Information System (INIS)

    The growth and optical properties of InAs quantum dots on a pure zinc blende InP nanowire are investigated. The quantum dots are formed in Stranski-Krastanov mode and exhibit pure zinc blende crystal structure. A substantial blueshift of the dots peak with a cube-root dependence on the excitation power is observed, suggesting a type-II band alignment. The peak position of dots initially red-shifts and then blue-shifts with increasing temperature, which is attributed to the carrier redistribution among the quantum dots. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Fabrication and optical properties of type-II InP/InAs nanowire/quantum-dot heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xin; Zhang, Xia; Li, Junshuai; Wu, Yao; Li, Bang; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing, 100876 (China)

    2016-02-15

    The growth and optical properties of InAs quantum dots on a pure zinc blende InP nanowire are investigated. The quantum dots are formed in Stranski-Krastanov mode and exhibit pure zinc blende crystal structure. A substantial blueshift of the dots peak with a cube-root dependence on the excitation power is observed, suggesting a type-II band alignment. The peak position of dots initially red-shifts and then blue-shifts with increasing temperature, which is attributed to the carrier redistribution among the quantum dots. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Transforming quantum operations: quantum supermaps

    OpenAIRE

    Chiribella, G.; D'Ariano, G. M.; Perinotti, P.

    2008-01-01

    We introduce the concept of quantum supermap, describing the most general transformation that maps an input quantum operation into an output quantum operation. Since quantum operations include as special cases quantum states, effects, and measurements, quantum supermaps describe all possible transformations between elementary quantum objects (quantum systems as well as quantum devices). After giving the axiomatic definition of supermap, we prove a realization theorem, which shows that any sup...

  1. Quantum correlation via quantum coherence

    OpenAIRE

    Yu, Chang-shui; Zhang, Yang; Zhao, Haiqing

    2014-01-01

    Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes ...

  2. Electron-beam-induced dislocations in GaAs and InP single crystals

    International Nuclear Information System (INIS)

    Dislocations have been induced in GaAs and InP single crystals by the electron beam exposure in a scanning electron microscope, with neither a mechanical bending nor a special pretreatment of the specimens. The generation and movement of the dislocations were not dependent upon the electron beam energy, crystal orientation, dopant nature, or doping level, but only on the electron beam current; a beam current of (1--2)x10-6 A was found to be the threshold for the dislocation release. By increasing the beam current up to 5x10-6 A, As or P losses from the specimen surface have been evidenced. In GaAs (001)-oriented crystals, the dislocations were found to be of pure edge type with the Burgers vector normal to the sample surface. A climb process, involving As or P vacancy migration, has been assumed to be the physical mechanism responsible for the dislocation origin

  3. Radiation hardening of InP solar cells for space applications

    International Nuclear Information System (INIS)

    The aim of this work is to develop a radiation resistant thin InP-based solar cells for space applications on more mechanically resistant, lighter, and cheaper substrates. In this paper, we present the development of a p+/nn+ InP-based solar cell structures with very thin emitter and base layers. A thin emitter helps to increase the collection of carriers generated by high energy incident photons from the solar spectrum. The use of a thin n base structure should improve the radiation resistance of this already radiation resistant technology. A remarkable improvement of high energy photons response is shown for InP solar cells with emitters 400 A thick

  4. Small- and large-signal modeling of InP HBTs in transferred-substrate technology

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas;

    2014-01-01

    In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a...... direct parameter extraction methodology dedicated to III–V based HBTs. It is shown that the modeling of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small......-signal model structure are employed as a starting point for the extraction of a large-signal model. The developed large-signal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies....

  5. Modeling of InP HBTs in Transferred-Substrate Technology for Millimeter-Wave Applications

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas;

    2013-01-01

    In this paper, the modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. At first, a direct parameter extraction methodology dedicated to III-V based HBTs is employed to determine the small-signal equivalent circuit parameters from...... measured S-parameters. It is shown that the model prediction of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small-signal model structure are employed as a starting...... point for the extraction of a large-signal model. The developed largesignal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies (77 GHz)....

  6. Determining the base resistance of InP HBTs: An evaluation of methods and structures

    Science.gov (United States)

    Nardmann, Tobias; Krause, Julia; Pawlak, Andreas; Schroter, Michael

    2016-09-01

    Many different methods can be found in the literature for determining both the internal and external base series resistance based on single transistor terminal characteristics. Those methods are not equally reliable or applicable for all technologies, device sizes and speeds. In this review, the most common methods are evaluated regarding their suitability for InP heterojunction bipolar transistors (HBTs) based on both measured and simulated data. Using data generated by a sophisticated physics-based compact model allows an evaluation of the extraction method precision by comparing the extracted parameter value to its known value. Based on these simulations, this study provides insight into the limitations of the applied methods, causes for errors and possible error mitigation. In addition to extraction methods based on just transistor terminal characteristics, test structures for separately determining the components of the base resistance from sheet and specific contact resistances are discussed and applied to serve as reference for the experimental evaluation.

  7. Effects of pressure on deep levels in semiconductors: The MFe center in InP

    International Nuclear Information System (INIS)

    This work investigated the effects of hydrostatic pressure on the properties and bistability of the scientifically challenging and technologically important deep MFe center in iron (Fe)-doped, n-type indium phosphide (InP). When occupied by electrons, the center can be reversibly placed in either of two configurations, termed A and B, by the proper choice of electric biasing conditions and temperature. Pressure has a very large influence on the balance between these two configurations, favoring A over B. Above 8 kbar essentially only the A configuration is observed. This result, along with detailed studies of the effects of pressure on the energetics of the two configurations and on the kinetics of the B→A transformation, provide important new insights about the nature of the two configurations and their associated deep levels. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Radiation-hard, high efficiency InP solar cell and panel development

    International Nuclear Information System (INIS)

    Indium phosphide solar cells with efficiencies over 19% (Air mass zero, 25 degrees C) and area of 4 cm2 have been made and incorporated into prototype panels. The panels will be tested in space to confirm the high radiation resistance expected from InP solar cells, which makes the material attractive for space use, particularly in high-radiation orbits. Laboratory testing indicated an end-of-life efficiency of 15.5% after 1015 1 MeV electrons, and 12% after 1016. These cells are made by metalorganic chemical vapor deposition, and have a shallow homojunction structure. The manufacturing process is amendable to scale-up to larger volumes; more than 200 cells were produced in the laboratory operation. Cell performance, radiation degradation, annealing behavior, and results of deep level transient spectroscopy studies are presented in this paper

  9. Channeling investigations of MeV Zn implanted InP

    Science.gov (United States)

    Kling, A.; Krause, H.; Flagmeyer, R.-H.; Vogt, J.; Butz, T.

    1995-03-01

    The high-energy Zn + ion implantation of InP is a promising method for the formation of buried p-type conducting layers. Defect properties and inclusion mechanism of zinc implanted samples with energies of 1.2 and 2.5 MeV to doses of 5 × 10 14-5 × 10 15 cm -2 at a temperature of 200°C were investigated with ion beam methods, XTEM and SNMS to some extent. Also the influence of rapid thermal annealing on the structural properties was studied. After implantation we found no evidence for amorphization or extended defects but point-like defects. During annealing the surface region recovered nearly completely while in depth the point-like defects agglomerated in dislocation loops. Further we observed a remarkable redistribution of the Zn atoms due to annealing.

  10. Scientific and technical progress in high-energy astrophysics at INPE

    International Nuclear Information System (INIS)

    The recent advances in high-energy Astrophysics pertains to the study of compact objects in galactic nuclei, binary systems and pulsars. These aspects are best understood by the study of the emissions in X- and gamma rays of these objects through the temporal variation in flux and spectrum. The Southern Hemisphere offers some of the unique objects for investigations such as galactic center, the Vela pulsar etc. For high temporal and spectra resolution studies two telescopes 'GeLi' and 'Pulsar' were designed and constructed. To support these scientific activities, a program in balloon launching and data acquisition facilities has been developed since 1971. The 'Balloon Launching Center' of INPE has capacity to launch balloons of -850,000 m3 with payloads weighting about 1,000 Kg. Taking advantage of these facilities, project 'Bantar', with the goal to measure the atmospheric gamma-ray radiation in the Antartic Region, is under progress. (Author)

  11. Locally measuring the adhesion of InP directly bonded on sub-100 nm patterned Si

    Science.gov (United States)

    Pantzas, K.; Le Bourhis, E.; Patriarche, G.; Troadec, D.; Beaudoin, G.; Itawi, A.; Sagnes, I.; Talneau, A.

    2016-03-01

    A nano-scale analogue to the double cantilever experiment that combines instrumented nano-indentation and atomic force microscopy is used to precisely and locally measure the adhesion of InP bonded on sub-100 nm patterned Si using oxide-free or oxide-mediated bonding. Surface-bonding energies of 0.548 and 0.628 J m-2, respectively, are reported. These energies correspond in turn to 51% and 57% of the surface bonding energy measured in unpatterned regions on the same samples, i.e. the proportion of unetched Si surface in the patterned areas. The results show that bonding on patterned surfaces can be as robust as on unpatterned surfaces, provided care is taken with the post-patterning surface preparation process and, therefore, open the path towards innovative designs that include patterns embedded in the Si guiding layer of hybrid III-V/Si photonic integrated circuits.

  12. Si Incorporation in InP Nanowires Grown by Au-Assisted Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Lorenzo Rigutti

    2009-01-01

    Full Text Available We report on the growth, structural characterization, and conductivity studies of Si-doped InP nanowires grown by Au-assisted molecular beam epitaxy. It is shown that Si doping reduces the mean diffusion length of adatoms on the lateral nanowire surface and consequently reduces the nanowire growth rate and promotes lateral growth. A resistivity as low as 5.1±0.3×10−5 Ω⋅cm is measured for highly doped nanowires. Two dopant incorporation mechanisms are discussed: incorporation via catalyst particle and direct incorporation on the nanowire sidewalls. The first mechanism is shown to be less efficient than the second one, resulting in inhomogeneous radial dopant distribution.

  13. Identification of vacancy type defects in low and high energy nitrogen ion implanted InP

    International Nuclear Information System (INIS)

    Depth resolved positron annihilation measurements were carried out on 85 keV and 1 MeV nitrogen ion implanted InP samples. The defect sensitive S-parameter and R-parameter values for the low energy implantations confirm the presence of monovacancies up to a dose of 1015 cm-2 and coexistence of monovacancies and divacancies for 1016 cm-2 dose sample. Corroborative glancing incidence x-ray diffraction measurements on the highest dose sample revealed that the sample is amorphized. For high energy implantation, it is found that vacancy-defects are present right from the near-surface region and these defects are identified to be monovancancies, based on the observed S- and R-parameters. A comparison of the results for the low and high energy implantations is made

  14. Frequency stability of InP HBT over 0.2 to 220 GHz

    International Nuclear Information System (INIS)

    The frequency stabilities of InP DHBTs in a broadband over 1 to 220 GHz are investigated. A hybrid π-topology small-signal model is used to accurately capture the parasitics of devices. The model parameters are extracted from measurements analytically. The investigation results show that the excellent agreement between the measured and simulated data is obtained in the frequency range 200 MHz to 220 GHz. The dominant parameters of the π-topology model, bias conditions and emitter area have significant effects on the stability factor K. The HBT model can be unconditionally stable by reasonable selection of the proper bias condition and the physical layout of the device. (semiconductor devices)

  15. A 20-GHz ultra-high-speed InP DHBT comparator

    International Nuclear Information System (INIS)

    An ultra-high-speed, master-slave voltage comparator circuit is designed and fabricated using InP/GaInAs double heterojunction bipolar transistor technology with a current gain cutoff frequency of 170 GHz. The complete chip die, including bondpads, is 0.75 × 1.04 mm2. It consumes 440 mW from a single −4 V power supply, excluding the clock part. 77 DHBTs have been used in the monolithic comparator. A full Nyquist test has been performed up to 20 GHz, with the input sensitivity varying from 6 mV at 10 GHz to 16 mV at 20 GHz. To our knowledge, this is the first InP based integrated circuit including more than 70 DHBTs, and it achieves the highest sampling rate found on the mainland of China. (semiconductor integrated circuits)

  16. A 20-GHz ultra-high-speed InP DHBT comparator

    Institute of Scientific and Technical Information of China (English)

    Huang Zhenxing; Zhou Lei; Su Yongbo; Jin Zhi

    2012-01-01

    An ultra-high-speed,master-slave voltage comparator circuit is designed and fabricated using InP/GaInAs double heterojunction bipolar transistor technology with a current gain cutoff frcquency of 170 GHz,The complete chip die,including bondpads,is 0.75 × 1.04 mm2.It consumes 440 mW from a single -4 V power supply,excluding the clock part.77 DHBTs have been used in the monolithic comparator.A full Nyquist test has been performed up to 20 GHz,with the input sensitivity varying from 6 mV at 10 GHz to 16 mV at 20 GHz.To our knowledge,this is the first InP based integrated circuit including more than 70 DHBTs,and it achieves the highest sampling rate found on the mainland of China.

  17. Studies on semiconductors based on InP with sub-ps response times

    International Nuclear Information System (INIS)

    The present work describes investigation of new material concepts accomplished using molecular-beam-epitaxy (MBE) growth for application in ultra-fast photonic components. Nominally undoped and Be doped GaInAs/AlInAs multiple-quantumwell structures (MQW) were grown by MBE at growth temperatures down to 100 C (LT-MBE) on semi-insulating InP substrates. Crystalline, electric and optical properties of as-grown and annealed structures were investigated. Energy states near the conduction band of GaInAs determine the electrical and optical properties of LT-MQWs. The dynamics of charge carrier relaxation was studied by means of pump and probe experiments. Measurements of the differential transmission when excited by an additional cw laser and measurements utilizing two closely sequenced pump pulses support the capability of Be doped as-grown (annealed) LT GaInAs/AlInAs MQW structures for use in optical switches at switching frequencies in the 1 Tbit/s (250 Gbit/s) range. The voltage-induced change of interband transmission of InP based quantumcascade-lasers (QCL) during pulsed mode operation was analyzed by means of 8 band k.p calculations. The impacts of varying charge carrier distributions and of electrically heated samples can be neglected compared to the dominating effect of the electrical field on the interband transmission. The impact of MBE growth parameters on the interface quality of AlAsSb/ GaInAs heterostructures were determined by means of Hall measurements, temperature- and intensity-dependent PL measurements and spectral measurements of the interband- and intersubband-absorption. The impact of In segregation and Sb diffusion on the intersubband absorption was analyzed on the basis of bandstructure calculations. Intersubband transitions at wavelengths of about 1.8 μm (1.55 μm) were successfully achieved in MQW (coupled QW) structures. (orig.)

  18. Coherent quantum cascade laser micro-stripe arrays

    Directory of Open Access Journals (Sweden)

    G. M. de Naurois

    2011-09-01

    Full Text Available We have fabricated InP-based coherent quantum cascade laser micro-stripe arrays. Phase-locking is provided by evanescent coupling between adjacent stripes. Stripes are buried into semi-insulating iron doped InP. Lasing at room temperature is obtained at 8.4μm for stripe arrays comprising up to 16 emitters. Pure supermode emission is demonstrated via farfield measurements and simulations. The farfield pattern shows a dual-lobe emission, corroborating the predicted phase-locked antisymmetric supermode emission.

  19. Coherent quantum cascade laser micro-stripe arrays

    OpenAIRE

    G. M. de Naurois; Carras, M.; B. Simozrag; O. Patard; Alexandre, F.; X. Marcadet

    2011-01-01

    We have fabricated InP-based coherent quantum cascade laser micro-stripe arrays. Phase-locking is provided by evanescent coupling between adjacent stripes. Stripes are buried into semi-insulating iron doped InP. Lasing at room temperature is obtained at 8.4μm for stripe arrays comprising up to 16 emitters. Pure supermode emission is demonstrated via farfield measurements and simulations. The farfield pattern shows a dual-lobe emission, corroborating the predicted phase-locked antisymmetric su...

  20. Synthesis and Evaluation of Nanogold Bioconjugated with Trastuzumab as a Drug for Human Breast Cancer Cell Line

    International Nuclear Information System (INIS)

    carboxyl group by adding 1-ethyl-3-(3-dimethyl aminopropyl) Carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS) using cross-linking reaction. 2- Bioconjugation i.e.,binding the modified GNPs with the anti-Her2/neu antibody (Trastuzumab). All the above productswere characterized by using UV-Vis spectroscopy, FTIR, and zeta nanosizertechniques. Part III: Application of the abovenovel products (three types GNPs, biofunctionalized GNPs and bioconjugated GNPs, as well astrastuzumab alone) on human breast cancer cell line (SK-BR-3) and on an isolated fraction of whole blood, peripheral blood mononuclear cells (PBMCs) in vitro. The evaluation was done by cytotoxicity assay, viability assay using inverted and light microscopy, and ELISA-reader. Part IV: In clinical characterization of the disease two tumor marker [cancer antigen (CA15-3) and carcinoembryonic antigen (CEA)] were investigated as well as, sex steroid hormones (estradiol, progesterone, and testosterone ), lipid profile and total proteins in sera of (100) Iraqi women with breast cancer classified to two groups depending on their Her2/neuimmunohistochemistry status (group I (positive) and group II (negative)) patients were recruited Al-Amal Hospital in Baghdad city during the period from the beginning of June -2013 to end of Dec.-2013. Their ages ranged from (27-70) years with irregular of menstrual cycle because taking of hormonal therapy. The results were compared with (40) blood samples from apparently healthy women as control group. Results revealed a highly significant increase (p<0.001) in the levels of CA15-3 and decrease in CEA. The three sex steroid hormonesrevealed significant increase (p<0.001) in the patients group compared to the control group. Lipid profile and total proteins were significantly decreased (p<0.05) in negative Her2/neu group and increased in positive Her2/neu, except triglyceride. It was concluded that there was a positive associations between CA15-3 and CEA as well as between CA

  1. Quaternary Barrier InGaAs/AlInGaAs Terahertz Quantum Cascade Laser

    International Nuclear Information System (INIS)

    Full text: We report on properties of a quaternary barrier InGaAs/AlInGaAs terahertz quantum cascade laser grown on Fe doped InP substrate. The active layer was designed using a scheme based on bound-to-continuum four quantum wells. Al composition of 17% in the AlInGaAs barriers was used. Ridge laser devices with double metal Au-Au waveguide emitted at 3.4 THz with a threshold current density of 590 A/cm2 at 10 K. The maximum operation temperature was 130 K. (author)

  2. Effect of III-V on insulator structure on quantum well intermixing

    Science.gov (United States)

    Takashima, Seiya; Ikku, Yuki; Takenaka, Mitsuru; Takagi, Shinichi

    2016-04-01

    To achieve the monolithic active/passive integration on the III-V CMOS photonics platform, quantum well intermixing (QWI) on III-V on insulator (III-V-OI) is studied for fabricating multi-bandgap III-V-OI wafers. By optimizing the QWI condition for a 250-nm-thick III-V layer, which contains a five-layer InGaAsP-based multi-quantum well (MQW) with 80-nm-thick indium phosphide (InP) cladding layers, we have successfully achieved a photoluminescence (PL) peak shift of over 100 nm on the III-V-OI wafer. We have also found that the progress of QWI on the III-V-OI wafer is slower than that on the InP bulk wafer regardless of the buried oxide (BOX) thickness, bonding interface materials, and handle wafers. We have also found that the progress of QWI on the III-V-OI wafer is slower than that on the InP bulk wafer regardless of the buried oxide (BOX) thickness, bonding interface materials, and bulk support wafers on which the III-V-OI structure is formed (handle wafers). By comparing between the measured PL shift and simulated diffusions of phosphorus vacancies and interstitials during QWI, we have found that the slow QWI progress in the III-V-OI wafer is probably attributed to the enhanced recombination of vacancies and interstitials by the diffusion blocking of vacancies and interstitials at the BOX interface.

  3. Quantum Instantons and Quantum Chaos

    OpenAIRE

    Jirari, H.; Kröger, H.; Luo, X. Q.; Moriarty, K. J. M.; Rubin, S. G.

    1999-01-01

    Based on a closed form expression for the path integral of quantum transition amplitudes, we suggest rigorous definitions of both, quantum instantons and quantum chaos. As an example we compute the quantum instanton of the double well potential.

  4. Quantum metrology

    International Nuclear Information System (INIS)

    The statistical error is ineluctable in any measurement. Quantum techniques, especially with the development of quantum information, can help us squeeze the statistical error and enhance the precision of measurement. In a quantum system, there are some quantum parameters, such as the quantum state, quantum operator, and quantum dimension, which have no classical counterparts. So quantum metrology deals with not only the traditional parameters, but also the quantum parameters. Quantum metrology includes two important parts: measuring the physical parameters with a precision beating the classical physics limit and measuring the quantum parameters precisely. In this review, we will introduce how quantum characters (e.g., squeezed state and quantum entanglement) yield a higher precision, what the research areas are scientists most interesting in, and what the development status of quantum metrology and its perspectives are. (topical review - quantum information)

  5. Quantum Computation and Quantum Information

    OpenAIRE

    Wang, Yazhen

    2012-01-01

    Quantum computation and quantum information are of great current interest in computer science, mathematics, physical sciences and engineering. They will likely lead to a new wave of technological innovations in communication, computation and cryptography. As the theory of quantum physics is fundamentally stochastic, randomness and uncertainty are deeply rooted in quantum computation, quantum simulation and quantum information. Consequently quantum algorithms are random in nature, and quantum ...

  6. Fluorescence of quantum dots on e-beam patterned and DNA origami substrates

    Science.gov (United States)

    Corrigan, Timothy D.; Kessinger, Matthew; Kidd, Jesse; Neff, David; Rahman, Masudur; Norton, Michael L.

    2015-05-01

    Attachment of quantum dots or fluorescent molecules to gold nanoparticles has a variety of optical labeling and sensory applications. In this study, we use both e-beam lithography and DNA origami to examine the fluorescence enhancement of fluorescent molecules and quantum dots with a systematic approach to understanding the contribution of gold nanoparticle size and interparticle spacing. The unique design of our patterns allows us to study the effects of size and spacing of the gold nanoparticles on the enhancement of fluorescence in one quick study with constant conditions - removing undesirable effects such as differences in concentration of quantum dots or other chemistry differences that plague multiple experiments. We also discuss the fluorescence and bonding of CdSe/ZnS quantum dots to both gold as well as DNA for use in self assembled DNA constructs. Specifically, bioconjugated CdSe/ZnS core/shell quantum dots were synthesized and functionalized with MPA using both traditional ligand exchange as well as newly developed in situ functionalization techniques used to increase the quantum yield of the quantum dots. We will present fluorescent images showing results of optimal size and spacing for fluorescence as well as demonstrating attachment chemistry of the quantum dots.

  7. Self-catalyzed growth of pure zinc blende 〈110〉 InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-13

    We demonstrate the self-catalyzed vapor-liquid-solid growth of 〈110〉 InP nanowires (NWs) by metal organic chemical vapor deposition. The 〈110〉 InP nanowire is formed via a spontaneous kinking from the original 〈111〉 growth direction, which is attributed to instabilities at the liquid/solid interface caused by a fast In incorporation into the droplet. The NW length before kinking has a nearly linear relationship with the diameter, offering a way to control the NW morphology for different applications. The 〈110〉 nanowire exhibits pure zinc blende crystal structure and a narrower emission linewidth in comparison with a typical 〈111〉 nanowire, demonstrating its potential applications in high-performance electronic and photonic devices.

  8. Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

    Institute of Scientific and Technical Information of China (English)

    HUANG Lei; SUN Bo; YAO Jian-quan; WANG Peng

    2008-01-01

    The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied.In collinear phase-matching,the optimum phase-matching wave bands of these two crystals are calculated.The optimum phase-matching wave bands in GaAs and InP are 0.95~1.38 μm and 0.7~0.96 μm respectively.The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed.The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed.It can serve for the following experiments as a theoretical evidence and a reference aswell.

  9. The LANDSAT system operated in Brazil by CNPq/INPE - results obtained in the area of mapping and future perspectives

    Science.gov (United States)

    Dejesusparada, N. (Principal Investigator); Barbosa, M. N.

    1981-01-01

    The LANDSAT system, operated in the country by CNPg/INPE since 1973, systematically acquires, produces, and distributes both multispectral and panchromatic images obtained through remote sensing satellites to thousands of researchers and technicians involved in the natural resources survey. To cooperate in the solution of national problems, CNPq/INPE is developing efforts in the area of manipulation of those images with the objective of making them useful as planimetric bases for the simple revision of already published maps or for its utilization as basic material in regions not yet reliability mapped. The results obtained from performed tests are presented and the existing limitations are discussed. The new system purchased to handle data from the next series of LANDSAT as well as from MAPSAT and SPOT which will be in operation within the 80's decade, and are designed not only for natural resources survey but also for the solution of cartographic problems.

  10. Self-catalyzed growth of pure zinc blende 〈110〉 InP nanowires

    International Nuclear Information System (INIS)

    We demonstrate the self-catalyzed vapor-liquid-solid growth of 〈110〉 InP nanowires (NWs) by metal organic chemical vapor deposition. The 〈110〉 InP nanowire is formed via a spontaneous kinking from the original 〈111〉 growth direction, which is attributed to instabilities at the liquid/solid interface caused by a fast In incorporation into the droplet. The NW length before kinking has a nearly linear relationship with the diameter, offering a way to control the NW morphology for different applications. The 〈110〉 nanowire exhibits pure zinc blende crystal structure and a narrower emission linewidth in comparison with a typical 〈111〉 nanowire, demonstrating its potential applications in high-performance electronic and photonic devices

  11. InAs nanostructures on InP (001) substrate with the insertion of a superthin AlAs layer

    Institute of Scientific and Technical Information of China (English)

    L(U) Xiao-jing; WU Ju; XU Bo; ZENG Yi-ping; WANG Biao-qiang; WANG Zhan-guo

    2007-01-01

    An AlAs layer of two or three monolayers was inserted beneath the strained InAs layer in the fabrication of InAs nanostructure on the In0.53Ga0.47As and In0.52Al0.48As buffer layer lattice-matched to InP(001) substrate using mo-lecular beam epitaxy. The effects of AlAs insertion on the InAs nanostructures were investigated and discussed.

  12. Validity of bioconjugated silica nanoparticles in comparison with direct smear, culture, and polymerase chain reaction for detection of Mycobacterium tuberculosis in sputum specimens

    Directory of Open Access Journals (Sweden)

    Ekrami A

    2011-11-01

    Full Text Available Alireza Ekrami1, Ali Reza Samarbaf-Zadeh2, Azar Khosravi1, Behrooz Zargar3, Mohamad Alavi1, Mansor Amin2, Alireza Kiasat3 1Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, 2Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, 3Department of Chemistry, School of Science, Shahid Chamran University, Ahvaz, Iran Background: Tuberculosis is a public health problem worldwide, and new easy to perform diagnostic methods with high accuracy are necessary for optimal control of the disease. Recently, fluorescent silica nanoparticles (FSNP has attracted immense interest for the detection of pathogenic microorganisms. The aim of this study was to detect Mycobacterium tuberculosis in clinical samples using bioconjugated FSNP compared with microscopic examination, polymerase chain reaction (PCR, nested PCR, and culture as the gold standard. Methods: In total, 152 sputum specimens were obtained from patients who were suspected to have pulmonary tuberculosis. All samples were examined by the four techniques described. Results: The assay showed 97.1% sensitivity (95% confidence interval [CI] 91–99.2 and 91.35% specificity (CI 78.3–97.1. Furthermore, assays using variable bacterial concentrations indicated that 100 colony forming units/mL of M. tuberculosis could be detected. There were no differences between the results obtained from two types of mouse monoclonal antibody against Hsp-65 and 16 KDa antigens. Conclusion: We performed this assay in a large number of clinical samples to confirm the diagnostic specificity and sensitivity of the test and can recommend its application for diagnosis of M. tuberculosis. We believe that this method is more convenient for routine diagnosis of M. tuberculosis in sputum and will be more easily applicable in the field, and with sufficient sensitivity. Keywords: Mycobacterium tuberculosis, fluorescent silica nanoparticles

  13. Recent improvements in detection performances of radiation detectors based on bulk semi-insulating InP

    CERN Document Server

    Dubecky, F; Necas, V; Sekacova, M; Fornari, R; Gombia, E; Bohácek, P; Krempasky, M; Pelfer, P G

    2002-01-01

    In this work, bulk semi-insulating (SI) InP wafers of four various producers have been used for the fabrication of radiation detectors. The tested detectors were prepared starting from the different materials in just one run in order to be sure that their performances were not influenced by technological processes. On one type of material various electrode technologies were used with the aim to analyze their role on the detector performances. The fabricated detectors were tested for detection performance by the sup 2 sup 4 sup 1 Am and sup 5 sup 7 Co gamma-ray sources at below room temperature. The best detector was calibrated and tested also using sup 1 sup 3 sup 3 Ba and sup 1 sup 3 sup 7 Cs gamma sources. The best detector gives an energy resolution of 7 keV FWHM and a charge collection efficiency (CCE) of 82% (59.5 keV photopeak) at a temperature of 216 K. According to our knowledge, these results are the best which have been obtained with InP radiation detectors till now. The operation of SI InP detector...

  14. Ab-initio Calculations of Electronic Properties of AlP, GaP and InP

    Science.gov (United States)

    Malozovsky, Yuriy; Saliev, Azizjon; Franklin, Lashaunda; Ekuma, Chinedu; Zhao, Guang-Lin; Bagayoko, Diola

    2014-03-01

    We present results from ab-initio, self consistent local density approximation (LDA) calculations of electronic and related properties of zinc blende aluminum, gallium and indium phosphides (AlP, GaP & InP). We employed a local density approximation (LDA) potential and implemented the linear combination of atomic orbitals (LCAO) formalism. This implementation followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Our calculated, indirect band gap of 2.56 eV for AlP, and of 2.14 eV for GaP, from Γ to X, are in excellent agreement with experimental values. Our calculated direct band gap of 1.40 eV, at Γ -point for InP is also in excellent agreement with experimental value. We also report calculated electron and hole effective masses for AlP, GaP and InP and total (DOS) and partial (pDOS) densities of states. This research is funded in part by the National Science Foundation (NSF) and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR] and NSF HRD-1002541, the US Department of Energy - National, Nuclear Security Administration (NNSA) (Award No. DE-NA0001861), LaSPACE, and LONI-SUBR.

  15. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  16. Quantum Simulation

    OpenAIRE

    Georgescu, I. M.; Ashhab, S.; Nori, Franco

    2013-01-01

    Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry and cosmology. Quantum simulat...

  17. Quantum Coins

    CERN Document Server

    Mosca, Michele

    2009-01-01

    One of the earliest cryptographic applications of quantum information was to create quantum digital cash that could not be counterfeited. In this paper, we describe a new type of quantum money: quantum coins, where all coins of the same denomination are represented by identical quantum states. We state desirable security properties such as anonymity and unforgeability and propose two candidate quantum coin schemes: one using black box operations, and another using blind quantum computation.

  18. Characterization of the S. cerevisiae inp51 mutant links phosphatidylinositol 4,5-bisphosphate levels with lipid content, membrane fluidity and cold growth.

    Science.gov (United States)

    Córcoles-Sáez, Isaac; Hernández, Maria Luisa; Martínez-Rivas, Jose Manuel; Prieto, Jose A; Randez-Gil, Francisca

    2016-03-01

    Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and its derivatives diphosphoinositol phosphates (DPIPs) play key signaling and regulatory roles. However, a direct function of these molecules in lipid and membrane homeostasis remains obscure. Here, we have studied the cold tolerance phenotype of yeast cells lacking the Inp51-mediated phosphoinositide-5-phosphatase. Genetic and biochemical approaches showed that increased metabolism of PI(4,5)P2 reduces the activity of the Pho85 kinase by increasing the levels of the DPIP isomer 1-IP7. This effect was key in the cold tolerance phenotype. Indeed, pho85 mutant cells grew better than the wild-type at 15 °C, and lack of this kinase abolished the inp51-mediated cold phenotype. Remarkably, reduced Pho85 function by loss of Inp51 affected the activity of the Pho85-regulated target Pah1, the yeast phosphatidate phosphatase. Cells lacking Inp51 showed reduced Pah1 abundance, derepression of an INO1-lacZ reporter, decreased content of triacylglycerides and elevated levels of phosphatidate, hallmarks of the pah1 mutant. However, the inp51 phenotype was not associated to low Pah1 activity since deletion of PAH1 caused cold sensitivity. In addition, the inp51 mutant exhibited features not shared by pah1, including a 40%-reduction in total lipid content and decreased membrane fluidity. These changes may influence the activity of membrane-anchored and/or associated proteins since deletion of INP51 slows down the transit to the vacuole of the fluorescent dye FM4-64. In conclusion, our work supports a model in which changes in the PI(4,5)P2 pool affect the 1-IP7 levels modulating the activity of Pho85, Pah1 and likely additional Pho85-controlled targets, and regulate lipid composition and membrane properties. PMID:26724696

  19. TiO{sub 2} as gate oxide on enhancement-mode N-channel sulfur-treated InP MOSFET

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.K.; Yen, C.F. [National Sun Yat-sen Univ., Taiwan (China). Dept. of Electrical Engineering

    2010-07-01

    This presentation discussed the use of titanium dioxide (TiO{sub 2}) in fuel cells as cathodes and catalysts, with particular reference to the feasibility of using TiO{sub 2} as the gate oxide in a MOSFET to make the integration more compact. An experiment was conducted aimed at fabricating an enhancement-mode n-channel sulfur-treated indium phosphide (InP) MOSFET with liquid phase deposition (LPD)-TiO{sub 2} as gate oxide. The TiO-2 film prepared by LPD on ammonium sulfide treated InP showed good electrical characteristics. The leakage currents can reach 2.1 x 10{sup -7} and 7.4 x 10{sup -7} A/cm{sup 2} at {+-}0.5 MV/cm. The fabricated enhancement-mode n-channel InP MOSFET exhibited the transconductance of 43 mS/mm and the electron field mobility of 348 cm{sup 2}/V s. The transconductance of MOSFET was higher with higher dielectric constant TiO{sub 2} as the gate oxide. Treatment of (NH{sub 4})2Sx prevented InP from oxidizing after cleaning and improved the interface properties of the MOS structure. Amorphous TiO{sub 2} film prepared by LPD can be deposited on InP substrate at near room temperature and can prevent the leakage current from the grain boundaries of polycrystalline structure. In this study, Zn doped p-type InP was used as the substrate. After cleaning and sulfidation, the InP was ready for MOSFET process. An aqueous solution of H{sub 2}TiF{sub 6} was used as the TiO{sub 2} deposition solution. It was concluded that the LPD-TiO2/S-InP capacitor had lower leakage current, higher k value, and lower Dit. 4 refs., 6 figs.

  20. Quantum Genetics, Quantum Automata and Quantum Computation

    OpenAIRE

    Baianu, Professor I. C.

    2004-01-01

    The concepts of quantum automata and quantum computation are studied in the context of quantum genetics and genetic networks with nonlinear dynamics. In a previous publication (Baianu,1971a) the formal concept of quantum automaton was introduced and its possible implications for genetic and metabolic activities in living cells and organisms were considered. This was followed by a report on quantum and abstract, symbolic computation based on the theory of categories, functors and natural trans...

  1. Ordered 1-D and 2-D InAs/InP quantum dot arrays at telecom wavelength

    International Nuclear Information System (INIS)

    Lateral one-dimensional (1-D) and two-dimensional (2-D) InAs/InP quantum dot (QD) arrangements are created by the concept of self-organized anisotropic strain engineering of InAs/InGaAsP superlattice (SL) templates on InP (100) and (311)B substrates by chemical-beam epitaxy (CBE). The SL templates comprise several-periods of an InAs QD layer plus a thin cap layer, post-growth annealing, and a separation layer. QDs order on top of the templates due to local strain recognition. Distinct preferential In adatom surface migration during annealing and substrate miscut lead to linear QD arrays along [001] for InP (100) substrates and a periodic square lattice aligned ±450 off [-233] for InP (311)B substrates. Optimization of the growth parameters balances In desorption and leads to well-separated and highly uniform QD arrays. Importantly, strong photoluminescence (PL) of defect-free InAs QD arrays is observed with the wavelength tuned into the 1.55-μim telecom region at room temperature through the insertion of GaAs interlayer beneath the QDs. Finally, the concept of self-organized anisotropic strain engineering for QD ordering is extended for formation of more complex architectures by combining it with step-engineering on shallow- and deep-patterned substrates. On the sidewall areas, the steps generated by the artificial patterns play the major role in determination of the In adatom surface migration during annealing, altering the QD arrays direction away from [001] on stripe-patterned InP (100) substrates. On the contrary, the sidewalls on patterned InP (311)B are faceted, not affecting the orientation of the 2-D InAs QD arrays.

  2. Quantum memory Quantum memory

    Science.gov (United States)

    Le Gouët, Jean-Louis; Moiseev, Sergey

    2012-06-01

    Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The

  3. Quantum Distinction: Quantum Distinctiones!

    Directory of Open Access Journals (Sweden)

    Dainis ZEPS

    2009-07-01

    Full Text Available How many distinctions, in Latin, quantum distinctions have? We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking should be equated with subject of physics (that of nature. For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinction may be considered as freedom of motion.

  4. Phosphazene like film formation on InP in liquid ammonia (223 K)

    International Nuclear Information System (INIS)

    An anodic photo-galvanostatic treatment at low current density (1 μA·cm−2) is carried out on n-InP semiconductor in liquid ammonia (223 K). The gradual chemical evolution of the surface is studied as a function of the anodic charge. Proof and reproducibility of the chemical transformation of the surface are clearly evidenced by X-ray photoelectron spectroscopy (XPS) analyses. Like by cyclic voltammetry, the perfect coverage of the InP surface by a thin phosphazene like film is also revealed by XPS data. However, a low anodic charge (≈ 0.5 mC·cm−2) is required by photo-galvanostatic treatment while a higher anodic charge (≈ 7 mC·cm−2) is involved by cyclic voltammetry. The excess of charge could be related to ammonia oxidation during the formation of the passivating film. This result proves the electrochemical oxidation of the solvent as a determinant step of the mechanism film formation. - Highlights: ► Cyclic voltammetry and galvanostatic modes on n-InP in liquid ammonia (223 K). ► A thin film growth is reached by photo-anodic polarization. ► The same phosphazene like film is evidenced by X-ray photoelectron spectroscopy. ► An excess of charge is observed by cyclic voltammetry. ► An electrochemical oxidation step of the solvent is assumed

  5. Improved Power Conversion Efficiency of InP Solar Cells Using Organic Window Layers

    Energy Technology Data Exchange (ETDEWEB)

    Li, N; Lee, K.; Renshaw, C. K.; Xiao, X.; Forrest, Stephen R.

    2011-01-01

    We employ the organic semiconductor 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) as a nanometer thick window layer for p-InP/indium tin oxide (ITO) Schottky barrierdiodesolar cells. The power conversion efficiency is enhanced compared to ITO/InP cells lacking the PTCDA window layer, primarily due to neutralizing InP surface state charges via hole injection from the PTCDA. This leads to an increased ITO/p-InP Schottky barrier height, and hence to an increased open circuit voltage. The power conversion efficiency of the cells increases from 13.2±0.5% for the ITO/InP cell to 15.4±0.4% for the ITO/4 nm PTCDA/p-InP cell under 1 sun, AM1.5G simulated solar illumination. The PTCDA window layer is also shown to contribute to the photocurrent by light absorption followed by exciton dissociation at the organic/inorganic semiconductor interface.

  6. Surface and subsurface damages in nanoindentation tests of compound semiconductor InP

    International Nuclear Information System (INIS)

    Nanoindentation tests were conducted on single-crystal indium phosphide (InP) using a Vickers indenter and a spherical indenter over a wide load range. The resulting indents were examined using scanning electron microscopy, cross-sectional transmission electron microscopy and selected area diffraction. Effects of the indenter type and indentation load on the surface cracking behavior, load–displacement characteristics and subsurface damage were investigated. The results showed that the cracking behavior and critical load for crack generation depends strongly on the indenter geometry and orientation. Pop-in events occur during loading in the case of the spherical indenter, but not in the case of the Vickers indenter. It was demonstrated that dislocations dominate the deformation mechanism, and no phase transformation occurs. The indenter contact immediately causes a high-density dislocation region, below which extend slip bands. The stress field of the indented zone was simulated by the finite element method, and the stress concentration regions corresponded to the high-density dislocation regions

  7. Bombardment-induced ripple topography on GaAs and InP

    International Nuclear Information System (INIS)

    Bombardment-induced ripples have possible application in nano-technology as nano-wires. This paper reviews some of the published experimental data of ripple formation on GaAs and InP resulting from noble gas, oxygen, nitrogen and cesium ion bombardment. The dependences of the ripples and their corresponding wavelengths on substrate temperature, areic dose and (to a lesser extent) angle of incidence were considered. The experimental results were tested against the predictions of the Bradley-Harper theory [J. Vac. Sci. Technol. A 6 (1988) 2390]. Surprisingly good agreement was obtained between the experimental data and this theory. This is probably due to the amorphisation of the substrates under ion bombardment and, thereby, minimising the effect of crystallographic-orientated self-diffusion on metals, and of energy barriers (Ehrlich-Schwoebel barriers) to interlayer surface diffusion. From the data of MacLaren et al. [J. Vac. Sci. Technol. A 10 (1992) 469], the activation energy for surface self-diffusion of GaAs in the temperature range 60-100 deg. C was determined as 0.26 eV

  8. Surface photovoltage studies of n-type and p-type InP

    Science.gov (United States)

    Thurgate, S. M.; Blight, K.; Laceusta, T. D.

    1994-05-01

    Surface photovoltage spectroscopy (SPV) was used to study the initial stages of oxidation of single crystal InP(110) in an attempt to understand the nature and origin of the surface states that develop. Distinct surface states were seen to develop on n-type as the surface was exposed to oxygen. A surface state, associated with cleavage damage, was also observed on p-type. A detailed fit to the experimental data was made by using a model of the dependence of surface charge on photon energy. This was used to unfold the position and intensity of the states. States trailing into the band gap from the bulk bands were seen on both n- and p-types. The analysis also indicated that pairs of isolated states, a donor and an acceptor state, were produced. On p-type, these were present on the clean, cleaved surface while they developed with oxygen exposure on n-type. These states are consistent with the point defect states proposed by the unified defect model. The time response of the SPV signal was also recorded for these surfaces. They were analysed by careful fitting to a model describing the charging and discharging characteristics. This revealed that the midgap state on n-type had a fast and a slow component.

  9. Doping evaluation of InP nanowires for tandem junction solar cells

    Science.gov (United States)

    Lindelöw, F.; Heurlin, M.; Otnes, G.; Dagytė, V.; Lindgren, D.; Hultin, O.; Storm, K.; Samuelson, L.; Borgström, M.

    2016-02-01

    In order to push the development of nanowire-based solar cells further using optimized nanowire diameter and pitch, a doping evaluation of the nanowire geometry is necessary. We report on a doping evaluation of n-type InP nanowires with diameters optimized for light absorption, grown by the use of metal-organic vapor phase epitaxy in particle-assisted growth mode using tetraethyltin (TESn) as the dopant precursor. The charge carrier concentration was evaluated using four-probe resistivity measurements and spatially resolved Hall measurements. In order to reach the highest possible nanowire doping level, we set the TESn molar fraction at a high constant value throughout growth and varied the trimethylindium (TMIn) molar fraction for different runs. Analysis shows that the charge carrier concentration in nanowires grown with the highest TMIn molar fraction (not leading to kinking nanowires) results in a low carrier concentration of approximately 1016 cm-3. By decreasing the molar fraction of TMIn, effectively increasing the IV/III ratio, the carrier concentration increases up to a level of about 1019 cm-3, where it seems to saturate. Axial carrier concentration gradients along the nanowires are found, which can be correlated to a combination of changes in the nanowire growth rate, measured in situ by optical reflectometry, and polytypism of the nanowires observed in transmission electron microscopy.

  10. Quantum stochastics

    CERN Document Server

    Chang, Mou-Hsiung

    2015-01-01

    The classical probability theory initiated by Kolmogorov and its quantum counterpart, pioneered by von Neumann, were created at about the same time in the 1930s, but development of the quantum theory has trailed far behind. Although highly appealing, the quantum theory has a steep learning curve, requiring tools from both probability and analysis and a facility for combining the two viewpoints. This book is a systematic, self-contained account of the core of quantum probability and quantum stochastic processes for graduate students and researchers. The only assumed background is knowledge of the basic theory of Hilbert spaces, bounded linear operators, and classical Markov processes. From there, the book introduces additional tools from analysis, and then builds the quantum probability framework needed to support applications to quantum control and quantum information and communication. These include quantum noise, quantum stochastic calculus, stochastic quantum differential equations, quantum Markov semigrou...

  11. Quantum cryptography

    OpenAIRE

    Gisin, Nicolas; Ribordy, Grégoire; Tittel, Wolfgang; Zbinden, Hugo

    2002-01-01

    Quantum cryptography could well be the first application of quantum mechanics at the single-quantum level. The rapid progress in both theory and experiment in recent years is reviewed, with emphasis on open questions and technological issues.

  12. InAs/InGaAsP Quantum Dots Emitting at 1.5 μm for Applications in Lasers

    DEFF Research Database (Denmark)

    Semenova, Elizaveta; Kulkova, Irina; Kadkhodazadeh, Shima; Schubert, Martin; Dunin-Borkowski, Rafal E.; Yvind, Kresten

    2011-01-01

    In this work the epitaxial growth of InAs quantum dots (QDs) in an InGaAsP matrix on an InP wafer is described. A new approach to shift the emission wavelength to the 1.5μm region using deposition of a thin GaAs capping layer on top of the QDs is suggested and exploited. Laser structures based on 5...

  13. Quantum Malware

    OpenAIRE

    Wu, Lian-Ao; Lidar, Daniel A.

    2005-01-01

    When quantum communication networks proliferate they will likely be subject to a new type of attack: by hackers, virus makers, and other malicious intruders. Here we introduce the concept of "quantum malware" to describe such human-made intrusions. We offer a simple solution for storage of quantum information in a manner which protects quantum networks from quantum malware. This solution involves swapping the quantum information at random times between the network and isolated, distributed an...

  14. Quantum Communication

    OpenAIRE

    Gisin, Nicolas; Thew, Rob

    2007-01-01

    Quantum communication, and indeed quantum information in general, has changed the way we think about quantum physics. In 1984 and 1991, the first protocol for quantum cryptography and the first application of quantum non-locality, respectively, attracted a diverse field of researchers in theoretical and experimental physics, mathematics and computer science. Since then we have seen a fundamental shift in how we understand information when it is encoded in quantum systems. We review the curren...

  15. Quantum Thermodynamics

    OpenAIRE

    Ronnie Kosloff

    2013-01-01

    Quantum thermodynamics addresses the emergence of thermodynamic laws from quantum mechanics. The viewpoint advocated is based on the intimate connection of quantum thermodynamics with the theory of open quantum systems. Quantum mechanics inserts dynamics into thermodynamics, giving a sound foundation to finite-time-thermodynamics. The emergence of the 0-law, I-law, II-law and III-law of thermodynamics from quantum considerations is presented. The emphasis is on consistency between the two the...

  16. SEM and XPS studies of nanohole arrays on InP(1 0 0) surfaces created by coupling AAO templates and low energy Ar + ion sputtering

    Science.gov (United States)

    Robert-Goumet, C.; Monier, G.; Zefack, B.; Chelda, S.; Bideux, L.; Gruzza, B.; Awitor, O. K.

    2009-10-01

    The aim of the present study is to demonstrate the feasibility to form well-ordered nanoholes on InP(1 0 0) surfaces by low Ar + ion sputtering process in UHV conditions from anodized aluminum oxide (AAO) templates. This process is a promising approach in creating ordered arrays of surface nanostructures with controllable size and morphology. To follow the Ar + ion sputtering effects on the AAO/InP surfaces, X-ray photoelectron spectroscopy (XPS) was used to determine the different surface species. In 4d and P 2p core level spectra were recorded on different InP(1 0 0) surfaces after ions bombardment. XPS results showed the presence of metallic indium on both smooth InP(1 0 0) and AAO/InP(1 0 0) surfaces. Finally, we showed that this experiment led to the formation of metallic In dropplets about 10 nm in diameter on nanoholes patterned InP surface while the as-received InP(1 0 0) surface generated metallic In about 60 nm in diameter.

  17. Self-Catalyzed Growth and Characterization of In(As)P Nanowires on InP(111)B Using Metal-Organic Chemical Vapor Deposition

    Science.gov (United States)

    Park, Jeung Hun; Pozuelo, Marta; Setiawan, Bunga P. D.; Chung, Choong-Heui

    2016-04-01

    We report the growth of vertical -oriented InAs x P1- x (0.11 ≤ x ≤ 0.27) nanowires via metal-organic chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates at 375 °C. Trimethylindium, tertiarybutylphosphine, and tertiarybutylarsine are used as the precursors, corresponding to P/In and As/In molar ratios of 29 and 0.01, respectively. The as-grown nanowire growth morphologies, crystallinity, composition, and optical characteristics are determined using a combination of scanning and transmission electron microscopies, electron diffraction, and X-ray photoelectron, energy dispersive X-ray, and Raman spectroscopies. We find that the InAs x P1- x nanowires are tapered with narrow tops, wider bases, and In-rich In-As alloy tips, characteristic of vapor-liquid-solid process. The wires exhibit a mixture of zinc blende and wurtzite crystal structures and a high density of structural defects such as stacking faults and twins. Our results suggest that the incorporation of As into InP wires decreases with increasing substrate temperature. The Raman spectra obtained from the In(As)P nanowires reveal a red-shift and lower intensity of longitudinal optical mode relative to both InP nanowires and InP(111)B bulk, due to the incorporation of As into the InP matrix.

  18. Self-Catalyzed Growth and Characterization of In(As)P Nanowires on InP(111)B Using Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Park, Jeung Hun; Pozuelo, Marta; Setiawan, Bunga P D; Chung, Choong-Heui

    2016-12-01

    We report the growth of vertical -oriented InAs x P1-x (0.11 ≤ x ≤ 0.27) nanowires via metal-organic chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates at 375 °C. Trimethylindium, tertiarybutylphosphine, and tertiarybutylarsine are used as the precursors, corresponding to P/In and As/In molar ratios of 29 and 0.01, respectively. The as-grown nanowire growth morphologies, crystallinity, composition, and optical characteristics are determined using a combination of scanning and transmission electron microscopies, electron diffraction, and X-ray photoelectron, energy dispersive X-ray, and Raman spectroscopies. We find that the InAs x P1-x nanowires are tapered with narrow tops, wider bases, and In-rich In-As alloy tips, characteristic of vapor-liquid-solid process. The wires exhibit a mixture of zinc blende and wurtzite crystal structures and a high density of structural defects such as stacking faults and twins. Our results suggest that the incorporation of As into InP wires decreases with increasing substrate temperature. The Raman spectra obtained from the In(As)P nanowires reveal a red-shift and lower intensity of longitudinal optical mode relative to both InP nanowires and InP(111)B bulk, due to the incorporation of As into the InP matrix. PMID:27094822

  19. Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

    OpenAIRE

    Natalia E. Mordvinova; Vinokurov, Alexander A; Lebedev, Oleg I.; Kuznetsova, Tatiana A.; Dorofeev, Sergey G.

    2015-01-01

    Zinc-doped InP(Zn) colloidal quantum dots (QDs) with narrow size distribution and low defect concentration were grown for the first time via a novel phosphine synthetic route and over a wide range of Zn doping. We report the influence of Zn on the optical properties of the obtained quantum dots. We propose a mechanism for the introduction of Zn in the QDs and show that the incorporation of Zn atoms into the InP lattice leads to the formation of Zn acceptor levels and a luminescence tail in th...

  20. Quantum dots

    CERN Document Server

    Borovitskaya, Elena

    2002-01-01

    In this book, leading experts on quantum dot theory and technology provide comprehensive reviews of all aspects of quantum dot systems. The following topics are covered: (1) energy states in quantum dots, including the effects of strain and many-body effects; (2) self-assembly and self-ordering of quantum dots in semiconductor systems; (3) growth, structures, and optical properties of III-nitride quantum dots; (4) quantum dot lasers. Contents: Low-Dimensional Systems (E Borovitskaya & M S Shur); Energy States in Quantum Dots (A J Williamson); Self-Organized Quantum Dots (A R Woll et al.); Grow

  1. Beyond quantum

    CERN Document Server

    Khrennikov, Andrei

    2014-01-01

    The present wave of interest in quantum foundations is caused by the tremendous development of quantum information science and its applications to quantum computing and quantum communication. It has become clear that some of the difficulties encountered in realizations of quantum information processing have roots at the very fundamental level. To solve such problems, quantum theory has to be reconsidered. This book is devoted to the analysis of the probabilistic structure of quantum theory, probing the limits of classical probabilistic representation of quantum phenomena.

  2. Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

    OpenAIRE

    Kröger, H.

    2003-01-01

    We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

  3. Overcoming power broadening of the quantum dot emission in a pure wurtzite nanowire

    Science.gov (United States)

    Reimer, M. E.; Bulgarini, G.; Fognini, A.; Heeres, R. W.; Witek, B. J.; Versteegh, M. A. M.; Rubino, A.; Braun, T.; Kamp, M.; Höfling, S.; Dalacu, D.; Lapointe, J.; Poole, P. J.; Zwiller, V.

    2016-05-01

    One of the key challenges in developing quantum networks is to generate single photons with high brightness, purity, and long temporal coherence. Semiconductor quantum dots potentially satisfy these requirements; however, due to imperfections in the surrounding material, the coherence generally degrades with increasing excitation power yielding a broader emission spectrum. Here we overcome this power-broadening regime and demonstrate an enhanced coherence at exciton saturation where the detected count rates are highest. We detect single-photon count rates of 460 000 counts per second under pulsed laser excitation while maintaining a single-photon purity greater than 99%. Importantly, the enhanced coherence is attained with quantum dots in ultraclean wurtzite InP nanowires, where the surrounding charge traps are filled by exciting above the wurtzite InP nanowire band gap. By raising the excitation intensity, the number of possible charge configurations in the quantum dot environment is reduced, resulting in a narrower emission spectrum. Via Monte Carlo simulations we explain the observed narrowing of the emission spectrum with increasing power. Cooling down the sample to 300 mK, we further enhance the single-photon coherence twofold as compared to operation at 4.5 K, resulting in a homogeneous coherence time, T2, of 1.2 ns, and two-photon interference visibility as high as 83% under strong temporal postselection (˜5 % without temporal postselection).

  4. Biofunctional quantum dots as fluorescence probe for cell-specific targeting.

    Science.gov (United States)

    Ag, Didem; Bongartz, Rebecca; Dogan, Leyla Eral; Seleci, Muharrem; Walter, Johanna-G; Demirkol, Dilek Odaci; Stahl, Frank; Ozcelik, Serdar; Timur, Suna; Scheper, Thomas

    2014-02-01

    We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies. PMID:24176888

  5. Quantum Optics with Quantum Gases

    OpenAIRE

    Mekhov, Igor B.; Ritsch, Helmut

    2009-01-01

    Quantum optics with quantum gases represents a new field, where the quantum nature of both light and ultracold matter plays equally important role. Only very recently this ultimate quantum limit of light-matter interaction became feasible experimentally. In traditional quantum optics, the cold atoms are considered classically, whereas, in quantum atom optics, the light is used as an essentially classical axillary tool. On the one hand, the quantization of optical trapping potentials can signi...

  6. Fabrication and optical characterization of large scale membrane containing InP/AlGaInP quantum dots.

    Science.gov (United States)

    Niederbracht, H; Hargart, F; Schwartz, M; Koroknay, E; Kessler, C A; Jetter, M; Michler, P

    2015-06-12

    Single-photon sources with a high extraction efficiency are a prerequisite for applications in quantum communication and quantum computation schemes. One promising approach is the fabrication of a quantum dot containing membrane structure in combination with a solid immersion lens and a metal mirror. We have fabricated an 80 nm thin semiconductor membrane with incorporated InP quantum dots in an AlGaInP double hetero barrier via complete substrate removal. In addition, a gold layer was deposited on one side of the membrane acting as a mirror. The optical characterization shows in detail that the unique properties of the quantum dots are preserved in the membrane structure. PMID:25994204

  7. Intraband relaxation time in wurtzite InGaN quantum-well lasers and comparison with experiment

    CERN Document Server

    Park, S H

    1999-01-01

    The intraband relaxation time for wurtzite (WZ) 3.5-nm In sub 0 sub . sub 1 sub 5 Ga sub 0 sub . sub 8 sub 5 N/In sub 0 sub . sub 0 sub 2 Ga sub 0 sub . sub 9 sub 8 N quantum well (QW) lasers is investigated theoretically. The results are also compared with those obtained from fitting the experimental data with a non-Markovian gain model with many-body effects. An intraband relaxation time of 25 fs is obtained from the comparison with experiment, which is in reasonably good agreement with the calculated value of 20 fs at the subband edge. These values are significantly shorter than those (40 - 100 sf) reported for zinc-blende crystals, such as InP and GaAs. This is because the hole effective masses of GaN are larger than those of GaAs and InP.

  8. Catalyst-free growth of InP nanowires on patterned Si (001) substrate by using GaAs buffer layer

    Science.gov (United States)

    Li, Shiyan; Zhou, Xuliang; Kong, Xiangting; Li, Mengke; Mi, Junping; Pan, Jiaoqing

    2016-04-01

    The catalyst-free metal organic vapor phase epitaxial growth of InP nanowires on silicon (001) substrate is investigated using selectively grown GaAs buffer layers in V-shaped trenches. A yield up to 70% of nanowires is self-aligned in uncommon directions under the optimized growth conditions. The evolution mechanism of self-aligned directions for nanowires is discussed and demonstrated. Using this growth method, we can achieve branched and direction switched InP nanowires by varying the V/III ratio in situ. The structure of the nanowires is characterized by scanning electron microscope and transmission electron microscopy measurements. The crystal structure of the InP nanowires is stacking-faults-free wurtzite with its c axis perpendicular to the nanowire axis.

  9. Quantum Chaos and Quantum Computers

    CERN Document Server

    Shepelyansky, D L

    2001-01-01

    The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer without any external decoherence. The onset of quantum chaos leads to quantum computer hardware melting, strong quantum entropy growth and destruction of computer operability. The time scales for development of quantum chaos and ergodicity are determined. In spite the fact that this phenomenon is rather dangerous for quantum computing it is shown that the quantum chaos border for inter-qubit coupling is exponentially larger than the energy level spacing between quantum computer eigenstates and drops only linearly with the number of qubits n. As a result the ideal multi-qubit structure of the computer remains rather robust against imperfections. This opens a broad parameter region for a possible realization of quantum computer. The obtained results are...

  10. Thin-Film Solar Cells with InP Absorber Layers Directly Grown on Nonepitaxial Metal Substrates

    KAUST Repository

    Zheng, Maxwell

    2015-08-25

    The design and performance of solar cells based on InP grown by the nonepitaxial thin-film vapor-liquid-solid (TF-VLS) growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and indium tin oxide transparent top electrode. An ex situ p-doping process for TF-VLS grown InP is introduced. Properties of the cells such as optoelectronic uniformity and electrical behavior of grain boundaries are examined. The power conversion efficiency of first generation cells reaches 12.1% under simulated 1 sun illumination with open-circuit voltage (VOC) of 692 mV, short-circuit current (JSC) of 26.9 mA cm-2, and fill factor (FF) of 65%. The FF of the cell is limited by the series resistances in the device, including the top contact, which can be mitigated in the future through device optimization. The highest measured VOC under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP. The design and performance of solar cells based on indium phosphide (InP) grown by the nonepitaxial thin-film vapor-liquid-solid growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and an indium tin oxide transparent top electrode. The highest measured open circuit voltage (VOC) under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP.

  11. Quantum matter

    International Nuclear Information System (INIS)

    The following topics are dealt with: Artificial atoms and molecules, tailored from solids, fractional flux quanta, molecular magnets, controlled interaction in quantum gases, the theory of quantum correlations in mott matter, cold gases, and mesoscopic systems, Bose-Einstein condensates on the chip, on the route to the quantum computer, a quantum computer in diamond. (HSI)

  12. Nitridation of InP(1 0 0) substrates studied by XPS spectroscopy and electrical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Talbi, A. [Laboratoire de Microelectronique Appliquee Universite Djillali Liabes de Sidi Bel Abbes 22000 (Algeria)]. E-mail: talbi_a02@yahoo.fr; Benamara, Z. [Laboratoire de Microelectronique Appliquee Universite Djillali Liabes de Sidi Bel Abbes 22000 (Algeria); Akkal, B. [Laboratoire de Microelectronique Appliquee Universite Djillali Liabes de Sidi Bel Abbes 22000 (Algeria); Gruzza, B. [Laboratoire des Sciences des Materiaux Pour l' Electronique et d' Automatique, Universite Blaise Pascal de Clermont II, Les Cezeaux, 63177 Aubiere Cedex (France); Bideux, L. [Laboratoire des Sciences des Materiaux Pour l' Electronique et d' Automatique, Universite Blaise Pascal de Clermont II, Les Cezeaux, 63177 Aubiere Cedex (France); Robert, C. [Laboratoire des Sciences des Materiaux Pour l' Electronique et d' Automatique, Universite Blaise Pascal de Clermont II, Les Cezeaux, 63177 Aubiere Cedex (France); Varenne, C. [Laboratoire des Sciences des Materiaux Pour l' Electronique et d' Automatique, Universite Blaise Pascal de Clermont II, Les Cezeaux, 63177 Aubiere Cedex (France); Chami, N. [Laboratoire de Microelectronique Appliquee Universite Djillali Liabes de Sidi Bel Abbes 22000 (Algeria)

    2006-11-15

    The nitrides of group III metals as InN are very important materials in optoelectronic (light-emitting diodes and laser diodes) and microelectronic areas. It is essential for the realisation of such devices to grow high quality nitride single crystals. In this paper, the nitridation of InP(1 0 0) surfaces has been studied in situ using X-ray photoelectron spectroscopy (XPS). After ionic cleaning by Ar{sup +} ions, metallic indium crystallites are created and the nitridation of the substrates is performed using a plasma glow discharge cell reaction with these indium clusters. We used the In{sub 4d} and P{sub 2p} core levels to monitor the chemical state of the surface and the coverage of the present species. We observed the creation of InN and PN bonds while the In-In metallic bonds decrease. This confirms the reaction between indium clusters and nitrogen species. A theoretical model based on stacked layers allows us to assert that we have produced almost two monolayers of indium nitride. In order to determine the quality of the elaborated nitride films and the electrical properties of the InN/InP interface we have used the I(V) electrical method. Analysis of the measured characteristics at room temperature allows the determination of the electrical parameters. The saturation current I {sub s}, the ideality factor {eta}, and the serial resistance R {sub s} are evaluated to 1.92 x 10{sup -6} A, 3.07 and 375 {omega}, respectively. The barrier height is determined at room temperature and is equal to 0.547 eV.

  13. Deterministic control of the quantum properties of single indium arsenide artificial atoms with indium phosphide nanoscale architectures

    Science.gov (United States)

    Kim, Danny

    This thesis presents optical spectra of single InAs quantum dots on InP with an unprecedented signal-to-noise ratio and spectral resolution that has facilitated comprehensive characterization and made a significant contribution to their understanding. InAs quantum dots on InP are the leading contenders for a variety of quantum electrooptic devices that require wavelengths in the 1.5 mum range, most notably triggered single/entangled photon sources for quantum key distribution. As of yet, spectroscopic data for InAs on InP has only provided proof of emission, but no high quality data has been available, preventing any conclusive understanding of their properties. The work presented in this thesis dramatically improves upon previous reports by key optimizations at each experimental stage: growth, processing, and optical setup. The spectra clearly resolve, for the first time, the structure within the s-shell and p-shell, with fine resolution, allowing quantitative evaluation of exciton complexes such as trions, biexcitons, and triplet states. By measuring numerous dots, the behavioral trends of these species with respect to dot geometry is deduced. Also, for the first time, magnetic-field dependent spectra are obtained for individual InAs/InP dots. A remarkable discovery was the strong relation of the exciton g-factor to dot height. This thesis also demonstrates deterministic nanometer-scale control of the quantum dot dimensions---with the goal being to exploit the structure/quantum property relation in these dots. This was accomplished by using the apex of an in-situ grown nanoscale InP pyramid as a nucleation site. The dimension of this top (001) surface on which the dot nucleates is responsive to manometer-scale changes in the pyramid base dimensions, which can be precisely controlled with lithography. The InAs grown on top of these mesas then conform to the size, where the available area can be purposely relaxed or constrained. For similar height, the resulting

  14. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  15. 110-GHz High-gain Flip-chip InP HEMT Amplifier with Resin Encapsulation on an Organic Substrate

    OpenAIRE

    Masuda, Satoshi; Kira, Hidehiko; Hirose, Tatsuya

    2004-01-01

    A high-gain amplifier monolithic microwave integrated circuit (MMIC) was developed using InP HEMT technology with inverted microstrip lines. The six-stage amplifier demonstrated a gain of 30 dB at 110 GHz. We also fabricated a resin-sealed flip-chip MMIC on a highly isolated cost-effective glass-epoxy substrate, achieving a gain of 28 dB at 110 GHz. To the best of our knowledge, this is the highest gain in the W-band for a flip-chip MMIC sealed with resin.

  16. Quantum annealing

    OpenAIRE

    Ruiz, Alfonso de la Fuente

    2014-01-01

    Brief description on the state of the art of some local optimization methods: Quantum annealing Quantum annealing (also known as alloy, crystallization or tempering) is analogous to simulated annealing but in substitution of thermal activation by quantum tunneling. The class of algorithmic methods for quantum annealing (dubbed: 'QA'), sometimes referred by the italian school as Quantum Stochastic Optimization ('QSO'), is a promising metaheuristic tool for solving local search problems in mult...

  17. Quantum Magnetohydrodynamics

    OpenAIRE

    Haas, Fernando

    2005-01-01

    The quantum hydrodynamic model for charged particle systems is extended to the cases of non zero magnetic fields. In this way, quantum corrections to magnetohydrodynamics are obtained starting from the quantum hydrodynamical model with magnetic fields. The quantum magnetohydrodynamics model is analyzed in the infinite conductivity limit. The conditions for equilibrium in ideal quantum magnetohydrodynamics are established. Translationally invariant exact equilibrium solutions are obtained in t...

  18. Quantum ontologies

    International Nuclear Information System (INIS)

    Quantum ontologies are conceptions of the constitution of the universe that are compatible with quantum theory. The ontological orientation is contrasted to the pragmatic orientation of science, and reasons are given for considering quantum ontologies both within science, and in broader contexts. The principal quantum ontologies are described and evaluated. Invited paper at conference: Bell's Theorem, Quantum Theory, and Conceptions of the Universe, George Mason University, October 20-21, 1988. 16 refs

  19. Quantum cloning

    OpenAIRE

    Scarani, Valerio; Iblisdir, Sofyan; Gisin, Nicolas; Acin, Antonio

    2005-01-01

    The impossibility of perfectly copying (or cloning) an arbitrary quantum state is one of the basic rules governing the physics of quantum systems. The processes that perform the optimal approximate cloning have been found in many cases. These "quantum cloning machines" are important tools for studying a wide variety of tasks, e.g. state estimation and eavesdropping on quantum cryptography. This paper provides a comprehensive review of quantum cloning machines (both for discrete-dimensional an...

  20. Morphology, luminescence, and electrical resistance response to H2 and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte

    International Nuclear Information System (INIS)

    Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1 x 1017 cm-3 and 1 x 1018 cm-3 in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H2 and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.

  1. Analysis of the surface photoabsorption signal during self-limited submonolayer growth of InP in metalorganic chemical vapor deposition

    CERN Document Server

    Lee, T W; Moon, Y B; Yoon, E J; Kim, Y D

    1999-01-01

    In situ, real-time monitoring of InP atomic layer epitaxy (ALE) was performed in low-pressure metalorganic chemical vapor deposition (LP-MOCVD) by surface photoabsorption (SPA). A self-limiting adsorption condition was obtained from the trimethylindium (TMIn) decomposition experiment at various conditions. It was found that the growth rate was less than 1 monolayer (ML)/cycle. From the in situ, real-time SPA measurement during InP ALE, the incomplete PH sub 3 decomposition on the methyl-terminated In surface was attributed to the self-limiting submonolayer growth per cycle.

  2. Quantum correlations; quantum probability approach

    OpenAIRE

    Majewski, W A

    2014-01-01

    This survey gives a comprehensive account of quantum correlations understood as a phenomenon stemming from the rules of quantization. Centered on quantum probability it describes the physical concepts related to correlations (both classical and quantum), mathematical structures, and their consequences. These include the canonical form of classical correlation functionals, general definitions of separable (entangled) states, definition and analysis of quantumness of correlations, description o...

  3. Quantum Computer Games: Quantum Minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  4. Quantum CPU and Quantum Simulating

    OpenAIRE

    Wang, An Min

    1999-01-01

    Making use of an universal quantum network or QCPU proposed by me [6], some special quantum networks for simulating some quantum systems are given out. Specially, it is obtained that the quantum network for the time evolution operator which can simulate, in general, Schr\\"odinger equation.

  5. Quantum CPU and Quantum Algorithm

    OpenAIRE

    Wang, An Min

    1999-01-01

    Making use of an universal quantum network -- QCPU proposed by me\\upcite{My1}, it is obtained that the whole quantum network which can implement some the known quantum algorithms including Deutsch algorithm, quantum Fourier transformation, Shor's algorithm and Grover's algorithm.

  6. Quantum Entanglement and Quantum Chromodynamics

    OpenAIRE

    Abbas, Afsar

    2000-01-01

    Non-locality or entanglement is an experimentally well established property of quantum mechanics. Here we study the role of quantum entanglement for higher symmetry group like $ SU(3_c) $, the gauge group of quantum chromodynamics (QCD). We show that the hitherto unexplained property of confinement in QCD arises as a fundamental feature of quantum entanglement in $ SU(3_c) $.

  7. Quantum teleportation and quantum information

    International Nuclear Information System (INIS)

    The scheme of quantum teleportation is described in a mathematically rigorous way, including analysis of the role and importance of quantum entanglement. The experiments with quantum teleportation performed in Innsbruck and in Rome are described in detail, and some differences between the two approaches are discussed. The elements of quantum information theory are introduced and compared with Shannon's classical information theory. The phenomenon of quantum teleportation is placed into a wider context of the developing quantum information theory, which enables quantum teleportation to be described by using the particle physics language. (Z.J.)

  8. Quantum Correlations in Quantum Cloning

    CERN Document Server

    Chakrabarty, Indranil

    2010-01-01

    We utilize quantum discord to charecterize the correlation present in Buzek-Hillery quantum copying machine \\cite{bh} (not necessarily universal quantum cloning machine). In other words we quantify the correlation present beetween the original and the replicated copy of the quantum state obtained at the outport port, Interestingly, we find some domain of the machine parameter, for which the quantum disord is non negative even in the mere absence of entanglement. These non zero values of the quantum discord is a strong signature for the presence of non classical correlations. This is one step forward evidence in the support of the fact that quantum discord and entanglement are not synonymous.

  9. Quantum noise and quantum communication

    Science.gov (United States)

    Jennewein, Thomas; Zeilinger, Anton

    2004-05-01

    We show how the probabilistic interpretation of quantum mechanics leads to unavoidable quantum noise, even for deterministic evolution of the quantum state. Far from being a nuisance, this consequent quantum randomness is at the heart of new concepts in technology. We discuss explicitly the quantum random number generator based on the partitition noise at the beam splitter. Another application of quantum noise is quantum cryptography, where the randomness of the detection event leads to the generation of a random cryptographic key at two locations without the necessity of transporting that key from A to B. Finally, we will show how quantum noise is an intrinsically important part of quantum teleportation, and we conclude with a brief discussion of the possibilities of free-space quantum communication.

  10. Bioconjugation of Serum Albumin to a Maleimide-appended Porphyrin/Cyclodextrin Supramolecular Complex as an Artificial Oxygen Carrier in the Bloodstream.

    Science.gov (United States)

    Kitagishi, Hiroaki; Kawasaki, Hiroki; Kano, Koji

    2015-08-01

    HemoCD is an inclusion complex of per-O-methylated β-cyclodextrin dimer and an iron(II) porphyrin, which forms a stable O2 complex in water. Therefore, hemoCD has the potential for use as a synthetic O2 carrier in mammalian blood. In this study, a hemoCD derivative having a maleimide group (Mal-hemoCD) was conjugated to a Cys residue of serum albumin via a Michael addition reaction in order to increase the circulation time of the O2 carrier. The O2 -binding affinities (P1/2 [Torr]) and half-lives (t1/2 [h]) of the O2 adducts at pH 7.4 and 25 °C were determined to be 9 Torr and 23 h for Mal-hemoCD, and 10 Torr and 14 h for albumin-conjugated hemoCD (Alb-hemoCD). Our pharmacokinetic study revealed that renal excretion of Alb-hemoCD was effectively suppressed and that half of injected Alb-hemoCD remained in blood at 3 h after injection. It is noteworthy that Mal-hemoCD also had a long circulation time because of the bioconjugation reaction that occurred during circulation in the bloodstream. PMID:26053595

  11. Quantum Histories and Quantum Gravity

    OpenAIRE

    Henson, Joe

    2009-01-01

    This paper reviews the histories approach to quantum mechanics. This discussion is then applied to theories of quantum gravity. It is argued that some of the quantum histories must approximate (in a suitable sense) to classical histories, if the correct classical regime is to be recovered. This observation has significance for the formulation of new theories (such as quantum gravity theories) as it puts a constraint on the kinematics, if the quantum/classical correspondence principle is to be...

  12. Quantum memristors

    Science.gov (United States)

    Pfeiffer, P.; Egusquiza, I. L.; Di Ventra, M.; Sanz, M.; Solano, E.

    2016-01-01

    Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems. PMID:27381511

  13. Quantum memristors.

    Science.gov (United States)

    Pfeiffer, P; Egusquiza, I L; Di Ventra, M; Sanz, M; Solano, E

    2016-01-01

    Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems. PMID:27381511

  14. DX centers in III-V semiconductors under hydrostatic pressure. [GaAs:Si; InP:S

    Energy Technology Data Exchange (ETDEWEB)

    Wolk, J.A.

    1992-11-01

    DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the Si[sub Ga] shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity.

  15. Giant corrugations in Bi2Se3 layers grown on high-index InP substrates

    Science.gov (United States)

    Takagaki, Y.; Jenichen, B.; Tominaga, J.

    2013-06-01

    Epitaxial growth of Bi2Se3 layers usually takes place in the (0001) orientation due to the stability of this surface terminated by the van der Waals bonds. Here, we show that the layers grown on InP(11n) substrates (n= 3, 4, and 5) are not (0001) oriented. The approximate lattice match at the heterointerface leads to an alignment between the [0001] direction of Bi2Se3 and the [111] direction of InP. The consequential tilt of the Bi2Se3(0001) plane with respect to the surface of the high-index substrates gives rise to a formation of giant corrugations consisting of the (0001) and (11¯00) facets. We demonstrate critical influences of the in-plane polarization and miscut of the substrates which emerge owing to the strong overlayer-substrate interaction in the semicoherent heteroepitaxy: Twin domains are eliminated and the layers are strained to the extent that the lattice symmetry is altered. We examine the Dirac band structure under strain using density functional calculations. The Dirac point shifts away from the Γ point and the spin degeneracy is lifted when the strain is in the Bi2Se3[11¯00] direction as the spatial inversion symmetry is removed.

  16. Modulation of electrical properties in Cu/n-type InP Schottky junctions using oxygen plasma treatment

    International Nuclear Information System (INIS)

    Using current–voltage (I–V) measurements, we investigated the effect of oxygen plasma treatment on the temperature-dependent electrical properties of Cu/n-type indium phosphide (InP) Schottky contacts at temperatures in the range 100–300 K. Changes in the electrical parameters were evident below 180 K for the low-plasma-power sample (100 W), which is indicative of the presence of a wider distribution of regions of low barrier height. Modified Richardson plots were used to obtain Richardson constants, which were similar to the theoretical value of 9.4 A cm−2 K−2 for n-type InP. This suggests that, for all the samples, a thermionic emission model including a spatially inhomogeneous Schottky barrier can be used to describe the charge transport phenomena at the metal/semiconductor interface. The voltage dependence of the reverse-bias current revealed that Schottky emission was dominant for the untreated and high-plasma-power (250 W) samples. For the low-plasma-power sample, Poole–Frenkel emission was dominant at low voltages, whereas Schottky emission dominated at higher voltages. Defect states and nonuniformity of the interfacial layer appear to be significant in the reverse-bias charge transport properties of the low-plasma-power sample. (paper)

  17. High Temperature Operation of 5.5μm Strain-Compensated Quantum Cascaded Lasers

    Institute of Scientific and Technical Information of China (English)

    LU Xiu-Zhen; LIU Feng-Qi; LIU Jun-Qi; JIN Peng; WANG Zhan-Guo

    2005-01-01

    @@ We develop 5.5-μm Inx Ga1-xAs/InyAl1-yAs strain-compensated quantum cascade lasers with InP and InGaAs cladding layers by using solid-source molecular-beam epitaxy. Pulse operation has been achieved up to 323K (50℃) for uncoated 20-μm-wide and 2-mm-long devices. These devices display an output power of 36mW with a duty cycle of 1% at room temperature. In continuous wave operation a record peak optical power of 10mW per facet has been measured at 83 K.

  18. Site control technique for quantum dots using electron beam induced deposition

    Science.gov (United States)

    Iizuka, Kanji; Jung, JaeHun; Yokota, Hiroshi

    2014-05-01

    To develop simple and high throughput sit definition technique for quantum dots (QDs), the electron beam induced deposition (EBID) method was used as desorption guide of phosphorus atoms form InP substrate. As the results one or a few indium (In) droplets (DLs) were created in the carbon grid pattern by thermal annealing at a temperature of 450°C for 10 min in the ultra high vacuum condition. The size of In DLs was larger than QDs, but arsenide DLs by molecular beam in growth chamber emitted wavelength of 1.028μm at 50K by photoluminescence measurement.

  19. Sub-nanometrically resolved chemical mappings of quantum-cascade laser active regions

    Science.gov (United States)

    Pantzas, Konstantinos; Beaudoin, Grégoire; Patriarche, Gilles; Largeau, Ludovic; Mauguin, Olivia; Pegolotti, Giulia; Vasanelli, Angela; Calvar, Ariane; Amanti, Maria; Sirtori, Carlo; Sagnes, Isabelle

    2016-05-01

    A procedure that produces sub-nanometrically resolved chemical mappings of MOCVD-grown InGaAs/InAlAs/InP quantum cascade lasers is presented. The chemical mappings reveal that, although the structure is lattice-matched to InP, the InAlAs barriers do not attain the nominal aluminum content—48%—and are, in fact, InGaAlAs quaternaries. This information is used to adjust the aluminum precursor flow and fine-tune the composition of the barriers, resulting in a significant improvement of the fabricated lasers.

  20. Quantum trajectories

    CERN Document Server

    Chattaraj, Pratim Kumar

    2010-01-01

    The application of quantum mechanics to many-particle systems has been an active area of research in recent years as researchers have looked for ways to tackle difficult problems in this area. The quantum trajectory method provides an efficient computational technique for solving both stationary and time-evolving states, encompassing a large area of quantum mechanics. Quantum Trajectories brings the expertise of an international panel of experts who focus on the epistemological significance of quantum mechanics through the quantum theory of motion.Emphasizing a classical interpretation of quan

  1. Quantumness witnesses

    International Nuclear Information System (INIS)

    A recently proposed test of quantumness Alicki and Van Ryn (2008 J. Phys. A: Math. Theor. 41 062001) is put into a broader mathematical and physical perspective. The notion of quantumness witnesses is introduced, in analogy to entanglement witnesses, and is illustrated by examples of single qubit and many-body systems with additive observables. We also compare our proposal with the quantumness test based on quantum correlations (entanglement) and Bell inequalities, and go on to discuss a class of quantumness witnesses associated with the phase-space representation of quantum mechanics

  2. Quantitative strain mapping of InAs/InP quantum dots with 1 nm spatial resolution using dark field electron holography

    OpenAIRE

    Cooper, David; Rouviere, Jean-Luc; Béché, Armand; Kadkhodazadeh, Shima; Semenova, Elizaveta; Yvind, Kresten; Dunin-Borkowski, Rafal E.

    2011-01-01

    The optical properties of semiconductor quantum dots are greatly influenced by their strain state. Dark field electron holography has been used to measure the strain in InAs quantum dots grown in InP with a spatial resolution of 1 nm. A strain value of 5.4% +/- 0.1% has been determined which is consistent with both measurements made by geometrical phase analysis of high angle annular dark field scanning transmission electron microscopy images and with simulations. (C) 2011 American Institute ...

  3. Optical reading of field-effect transistors by phase-space absorption quenching in a single InGaAs quantum well conducting channel

    Science.gov (United States)

    Chemla, D. S.; Bar-Joseph, I.; Klingshirn, C.; Miller, D. A. B.; Kuo, J. M.

    1987-03-01

    Absorption switching in a semiconductor quantum well by electrically varying the charge density in the quantum well conducting channel of a selectively doped heterostructure transistor is reported for the first time. The phase-space absorption quenching (PAQ) is observed at room temperature in an InGaAs/InAlAs grown on InP FET, and it shows large absorption coefficient changes with relatively broad spectral bandwidth. This PAQ is large enough to be used for direct optical determination of the logic state of the FET.

  4. Growth and characterization of InP/In{sub 0.48}Ga{sub 0.52}P quantum dots optimized for single-photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Ugur, Asli

    2012-08-28

    In this work the growth of self-assembled InP/InGaP quantum dots, as well as their optical and structural properties are presented and discussed. The QDs were grown on In{sub 0.48}Ga{sub 0.52}P, lattice matched to GaAs. Self-assembled InP quantum dots are grown using gas-source molecular beam epitaxy over a wide range of InP deposition rates, using an ultra-low growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/μm{sup 2} is realized. The resulting isolated InP quantum dots are individually characterized without the need for lithographical patterning and masks on the substrate. Both excitonic and biexcitonic emissions are observed from single dots, appearing as doublets with a fine-structure splitting of 320 μeV. Hanbury Brown-Twiss correlation measurements for the excitonic emission under cw excitation show anti-bunching behavior with an autocorrelation value of g{sup (2)}(0)=0.2. This system is applicable as a single-photon source for applications such as quantum cryptography. The formation of well-ordered chains of InP quantum dots on GaAs (001) substrates by using self-organized In{sub 0.48}Ga{sub 0.52}P surface undulations as a template is also demonstrated. The ordering requires neither stacked layers of quantum dots nor substrate misorientation. The structures are investigated by polarization-dependent photoluminescence together with transmission electron microscopy. Luminescence from the In{sub 0.48}Ga{sub 0.52}P matrix is polarized in one crystallographic direction due to anisotropic strain arising from a lateral compositional modulation. The photoluminescence measurements show enhanced linear polarization in the alignment direction of quantum dots. A polarization degree of 66% is observed. The optical anisotropy is achieved with a straightforward heterostructure, requiring only a single layer of QDs.

  5. A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1.

    Directory of Open Access Journals (Sweden)

    Sarah H Reeder

    2016-05-01

    Full Text Available Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures-openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores-the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them.

  6. A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1.

    Science.gov (United States)

    Reeder, Sarah H; Lee, Byung Ha; Fox, Ronald; Dobritsa, Anna A

    2016-05-01

    Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures-openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores-the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them. PMID:27177036

  7. Room-temperature particle detectors with guard rings based on semi-insulating InP co-doped with Ti and Zn

    Czech Academy of Sciences Publication Activity Database

    Yatskiv, Roman; Žďánský, Karel; Pekárek, Ladislav

    2009-01-01

    Roč. 598, č. 3 (2009), s. 759-763. ISSN 0168-9002 R&D Projects: GA AV ČR KAN400670651 Institutional research plan: CEZ:AV0Z20670512 Keywords : radiation detector * InP * crystal growth Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.317, year: 2009

  8. Interfacial analysis of InP surface preparation using atomic hydrogen cleaning and Si interfacial control layers prior to MgO deposition

    International Nuclear Information System (INIS)

    The objective of this study is to investigate how the surface characteristics of indium phosphide (InP) can be modified through the use of atomic hydrogen (H*) cleaning and silicon interfacial control layers (Si ICL), prior to the deposition of MgO dielectric layers. X-ray photoelectron spectroscopy (XPS) analysis shows that the InP native oxide can be successfully removed using atomic hydrogen cleaning at a substrate temperature of 300 deg. C. However, atomic force microscopy (AFM) images display evidence for the growth of metallic In island features after H* cleaning, and subsequent deposition of MgO thin films on the H* cleaned surface resulted in high levels of interfacial indium oxide growth. It has also been shown that the deposition of thin (∼1 nm) Si layers on InP native oxide surfaces results in the transfer of oxygen from the InP substrate to the Si ICL and the formation of Si-InP bonds. XPS analysis indicates that MgO deposition and subsequent 500 deg. C annealing results in further oxidation of the Si layer. However, no evidence for the re-growth of interfacial In or P oxide species was observed, in contrast to observations on the H* cleaned surface.

  9. A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1

    Science.gov (United States)

    Reeder, Sarah H.; Lee, Byung Ha; Fox, Ronald; Dobritsa, Anna A.

    2016-01-01

    Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures–openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores–the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them. PMID:27177036

  10. Fe-contacts on InAs(100) and InP(100) characterised by conversion electron Mössbauer spectroscopy

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Gunnlaugsson, H.P; Weyer, G.;

    2005-01-01

    We have grown 4 nm thin films of Fe-57 on InAs(100) and InP(100) surfaces by use of MBE and studied the samples by Fe-57 conversion electron Mossbauer spectroscopy. In the case of InAs, the Mossbauer spectrum showed a sextet due to alpha-Fe and a further magnetically split component with slightly...

  11. Quantum robots and quantum computers

    Energy Technology Data Exchange (ETDEWEB)

    Benioff, P.

    1998-07-01

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  12. Quantum music

    CERN Document Server

    Putz, Volkmar

    2015-01-01

    We consider ways of conceptualizing, rendering and perceiving quantum music, and quantum art in general. Thereby we give particular emphasis to its non-classical aspects, such as coherent superposition and entanglement.

  13. Quantum Darwinism

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H [Los Alamos National Laboratory

    2008-01-01

    Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.

  14. Quantum interview

    CERN Document Server

    Valentini, Antony

    2014-01-01

    This paper collects into one place my replies to the questions posed by Maximilian Schlosshauer in his interview volume about the foundations of quantum mechanics, "Elegance and Enigma: The Quantum Interviews" (Springer, 2011).

  15. Quantum music

    OpenAIRE

    Putz, Volkmar; Svozil, Karl

    2015-01-01

    We consider ways of conceptualizing, rendering and perceiving quantum music, and quantum art in general. Thereby, we give particular emphasis to its non-classical aspects, such as coherent superposition and entanglement.

  16. Quantum Relativity

    OpenAIRE

    Ionescu, Lucian M

    2010-01-01

    Quantum Relativity is supposed to be a new theory, which locally is a deformation of Special Relativity, and globally it is a background independent theory including the main ideas of General Relativity, with hindsight from Quantum Theory. The qubit viewed as a Hopf monopole bundle is considered as a unifying gauge "group". Breaking its chiral symmetry is conjectured to yield gravity as a deformation of electromagnetism. It is already a quantum theory in the context of Quantum Information Dyn...

  17. Quantum Games

    CERN Document Server

    Eisert, J

    2000-01-01

    In these lecture notes we investigate the implications of the identification of strategies with quantum operations in game theory beyond the results presented in [J. Eisert, M. Wilkens, and M. Lewenstein, Phys. Rev. Lett. 83, 3077 (1999)]. After introducing a general framework, we study quantum games with a classical analogue in order to flesh out the peculiarities of game theoretical settings in the quantum domain. Special emphasis is given to a detailed investigation of different sets of quantum strategies.

  18. Quantum seals

    OpenAIRE

    Singh, Sudhir Kumar; Srikanth, R.

    2004-01-01

    A quantum seal is a way of encoding a message into quantum states, so that anybody may read the message with little error, while authorized verifiers can detect that the seal has been broken. We present a simple extension to the Bechmann-Pasquinucci majority-voting scheme that is impervious to coherent attacks, and further, encompasses sealing quantum messages by means of quantum encryption. The scheme is relatively easy to implement, requiring neither entanglement nor controlled operations d...

  19. Self-assembling Phage-Quantum Dot Nanocomplexes for Quantitative Biodetection

    Science.gov (United States)

    Clarke, Matthew; Kang, Hyeonggon; Hwang, Jeeseong

    2010-03-01

    Colloidal quantum dots (QDs) have been used for many biodetection applications because of their brightness and broad spectral coverage in multiplexed approaches. QD surfaces can be functionalized for bio-conjugation to enable self-assembly with other nanomaterials and biomolecules using biological or bio-inspired processes. We demonstrate a model bacterial detection system using phage-QD nanocomplexes. To engineer the nanocomplexes, we genetically modified phage to express lysine residues on the capsid region, resulting in biotin labeling during replication inside the host cell. The biotinylated phages were conjugated with QDs and employed for detection. Bacteriophages have specificity to bacteria, enabling targeted detection of specific strains. Brightness of QDs enables high-throughput optical detection. The properties of nanocomplexes and detection limit/sensitivity were quantitatively evaluated using integrated differential interference contrast and fluorescence microscopy and automated image-based cytometry technique.

  20. Quantum Teleportation

    OpenAIRE

    Slavnov, D. A.

    2009-01-01

    In the framework of an algebraic approach, we consider a quantum teleportation procedure. It turns out that using the quantum measurement nonlocality hypothesis is unnecessary for describing this procedure. We study the question of what material objects are information carriers for quantum teleportation.

  1. Quantum criticality

    OpenAIRE

    Coleman, P.; Schofield, A.J.

    2005-01-01

    As we mark the centenary of Albert Einstein's seminal contribution to both quantum mechanics and special relativity, we approach another anniversary--that of Einstein's foundation of the quantum theory of solids. But 100 years on, the same experimental measurement that puzzled Einstein and his contemporaries is forcing us to question our understanding of how quantum matter transforms at ultra-low temperatures.

  2. I, Quantum Robot: Quantum Mind control on a Quantum Computer

    OpenAIRE

    Zizzi, Paola

    2008-01-01

    The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

  3. Nano-photonics in III-V semiconductors for integrated quantum optical circuits

    Science.gov (United States)

    Wasley, Nicholas Andrew

    This thesis describes the optical spectroscopic measurements of III-V semiconductors used to investigate a number of issues related to the development of integrated quantum optical circuits. The disorder-limited propagation of photons in photonic crystal waveguides in the slow-light regime is investigated. The analysis of Fabry-Perot resonances is used to map the mode dispersion and extract the photon localisation length. Andersonlocalised modes are observed at high group indices, when the localisation lengths are shorter than the waveguide lengths, consistent with the Fabry-Perot analysis. A spin-photon interface based on two orthogonal waveguides is introduced, where the polarisation emitted by a quantum dot is mapped to a path-encoded photon. Operation is demonstrated by deducing the spin using the interference of in-plane photons. A second device directly maps right and left circular polarisations to anti-parallel waveguides, surprising for a non-chiral structure but consistent with an off-centre dot. Two dimensional photonic crystal cavities in GaInP and full control over the spontaneous emission rate of InP quantum dots is demonstrated by spectrally tuning the exciton emission energy into resonance with the fundamental cavity mode. Fourier transform spectroscopy is used to investigate the short coherence times of InP quantum dots in GaInP photonic crystal cavities. Additional technological developments are also presented including a quantum dot registration technique, electrical tuning of quantum dot emission and uniaxial strain tuning of H1 cavity modes.

  4. Different patterns of nuclear and mitochondrial penetration by the G3 PAMAM dendrimer and its biotin–pyridoxal bioconjugate BC-PAMAM in normal and cancer cells in vitro

    Science.gov (United States)

    Uram, Łukasz; Szuster, Magdalena; Filipowicz, Aleksandra; Gargasz, Krzysztof; Wołowiec, Stanisław; Wałajtys-Rode, Elżbieta

    2015-01-01

    The intracellular localization and colocalization of a fluorescently labeled G3 amine-terminated cationic polyamidoamine (PAMAM) dendrimer and its biotin–pyridoxal (BC-PAMAM) bioconjugate were investigated in a concentration-dependent manner in normal human fibroblast (BJ) and squamous epithelial carcinoma (SCC-15) cell lines. After 24 hours treatment, both cell lines revealed different patterns of intracellular dendrimer accumulation depending on their cytotoxic effects. Cancer cells exhibited much higher (20-fold) tolerance for native PAMAM treatment than fibroblasts, whereas BC-PAMAM was significantly toxic only for fibroblasts at 50 µM concentration. Fibroblasts accumulated the native and bioconjugated dendrimers in a concentration-dependent manner at nontoxic range of concentration, with significantly lower bioconjugate loading. After reaching the cytotoxicity level, fluorescein isothiocyanate-PAMAM accumulation remains at high, comparable level. In cancer cells, native PAMAM loading at higher, but not cytotoxic concentrations, was kept at constant level with a sharp increase at toxic concentration. Mander’s coefficient calculated for fibroblasts and cancer cells confirmed more efficient native PAMAM penetration as compared to BC-PAMAM. Significant differences in nuclear dendrimer penetration were observed for both cell lines. In cancer cells, PAMAM signals amounted to ~25%–35% of the total nuclei area at all investigated concentrations, with lower level (15%–25%) observed for BC-PAMAM. In fibroblasts, the dendrimer nuclear signal amounted to 15% at nontoxic and up to 70% at toxic concentrations, whereas BC-PAMAM remained at a lower concentration-dependent level (0.3%–20%). Mitochondrial localization of PAMAM and BC-PAMAM revealed similar patterns in both cell lines, depending on the extracellular dendrimer concentration, and presented significantly lower signals from BC-PAMAM, which correlated well with the cytotoxicity. PMID:26379435

  5. Development of novel n{sup +}-in-p Silicon Planar Pixel Sensors for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Unno, Y., E-mail: yoshinobu.unno@kek.jp [Institute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan); Gallrapp, C. [European Organization for Nuclear Research (CERN), CH-1211, Geneve 23 (Switzerland); Hori, R. [Institute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan); Idarraga, J. [Institut Universitaire de Technologie d' Orsay, Universite de Paris Sud, plateau de Moulon, 91400 Orsay (France); Mitsui, S. [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan); Nagai, R.; Kishida, T. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Ishida, A.; Ishihara, M.; Kamada, S.; Inuzuka, T.; Yamamura, K. [Solid-State Division, Hamamatsu Photonics K.K., 1126-1 Ichino-cho, Higashi-ku, Hamamatsu-shi, Shizuoka 435-8558 (Japan); Hara, K. [Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8571 (Japan); Ikegami, Y. [Institute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan); Jinnouchi, O. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Lounis, A. [Institut Universitaire de Technologie d' Orsay, Universite de Paris Sud, plateau de Moulon, 91400 Orsay (France); Takahashi, Y. [Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8571 (Japan); Takubo, Y.; Terada, S. [Institute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan); Hanagaki, K. [Department of Physics, Osaka University, Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043 (Japan); and others

    2013-01-21

    We have been developing highly radiation-tolerant n{sup +}-in-p planar pixel sensors for use in the high-luminosity LHC. Novel n{sup +}-in-p structures were made using various combinations of the bias structures (punch-through or polysilicon resistor), isolation structures (p-stop or p-spray), and thicknesses (320μm or 150μm). The 1-chip pixel modules with thin FE-I4 pixel sensors were evaluated using test beams, before and after 2×10{sup 15}n{sub eq}/cm{sup 2} irradiation. The full depletion voltages were estimated to be 44±10 V and 380±70 V, in the non-irradiated and the irradiated modules, respectively. A reduction of efficiency was observed in the vicinity of the four pixel corners and underneath the bias rail after the irradiation. The global efficiencies were >99% and >95% in the non-irradiated and the irradiated modules, respectively. The collected charges were uniform in the depth direction at bias voltages well above the full depletion voltages. The encapsulation of vulnerable edges with adhesive or parylene prevented HV sparking. Bump bonding with the SnAg solder bumps was performed at HPK with 150μm- and 320μm-thick sensors and chips. No disconnection of bumps was observed after 10 thermal cycles between −40 and +50 °C, with a temperature slew rate of >70K/min. -- Highlights: ► Novel n{sup +}-in-p pixel sensors were made of punch-through/poly-Si biasing, p-stop/p-spray isolation, and 320/150μm thickness. ► The thin pixel modules were evaluated in testbeams, before and after 2×10{sup 15}n{sub eq}/cm{sup 2} irradiation. ► A reduction of efficiency was observed in the vicinity of four-corners of pixels and underneath the bias rail after irradiation. ► Encapsulating the vulnerable edges with adhesive or parylene achieved prevention of HV sparking up to 1000 V. ► No disconnection of SnAg bump-bonds was observed in dummy modules after 10 thermal cycles with a slew rate of >70K/min.

  6. First step to Si photonics: synthesis of quantum dot light-emitters on GaP substrate by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Weiming; Bondi, Alexandre; Cornet, Charles; Folliot, Herve; Letoublon, Antoine; Boyer-Richard, Soline; Chevalier, Nicolas; Gicquel, Maud; Alsahwa, Bassem; Corre, Alain Le; Even, Jacky; Durand, Olivier; Loualiche, Slimane [CNRS UMR 6082 FOTON, INSA-Rennes, Rennes (France)

    2009-10-15

    We have grown InAs and InP quantum dots (QDs) on GaP substrate by Molecular Beam Epitaxy (MBE) and analysed them by Atomic Force Microscopy (AFM) and photoluminescence (PL). AFM images confirm the formation of InAs and InP QDs. Largest InAs QDs density is obtained at a growth temperature of 450 C and under an AsH{sub 3} flux of 0.3 SCCM. The evolution of QDs shape and absence of photoluminescence indicate a likely plastic relaxation of the strain between InAs and GaP. Concerning InP/GaP QDs, their lateral size, height and density indicate good quality QDs. Photoluminescence signal has been detected for capped InP/GaP QDs until 180 K. The unchanged peak position with respect to InP coverage is attributed to the nearly constant height of the QDs. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Quantum Logic and Quantum Computation

    OpenAIRE

    Pavicic, Mladen; Megill, Norman D.

    2008-01-01

    We use classes of Hilbert lattice equations for an alternative representation of Hilbert lattices and Hilbert spaces of arbitrary quantum systems that might enable a direct introduction of the states of the systems into quantum computers. More specifically, we look for a way to feed a quantum computer with algebraic equations of n-th order underlying an infinite dimensional Hilbert space description of quantum systems. A number of new results on states defined on Hilbert lattices are presente...

  8. Quantum cheques

    Science.gov (United States)

    Moulick, Subhayan Roy; Panigrahi, Prasanta K.

    2016-06-01

    We propose the idea of a quantum cheque scheme, a cryptographic protocol in which any legitimate client of a trusted bank can issue a cheque, that cannot be counterfeited or altered in anyway, and can be verified by a bank or any of its branches. We formally define a quantum cheque and present the first unconditionally secure quantum cheque scheme and show it to be secure against any no-signalling adversary. The proposed quantum cheque scheme can been perceived as the quantum analog of Electronic Data Interchange, as an alternate for current e-Payment Gateways.

  9. Synthesis, Copper(II) Complexation, (64)Cu-Labeling, and Bioconjugation of a New Bis(2-pyridylmethyl) Derivative of 1,4,7-Triazacyclononane.

    Science.gov (United States)

    Gasser, Gilles; Tjioe, Linda; Graham, Bim; Belousoff, Matthew J; Juran, Stefanie; Walther, Martin; Künstler, Jens-Uwe; Bergmann, Ralf; Stephan, Holger; Spiccia, Leone

    2008-03-01

    A new ligand derivative of 1,4,7-triazacyclononane (TACN), 2-[4,7-bis(2-pyridylmethyl)-1,4,7-triazacyclononan-1-yl]acetic acid ( 6), has been synthesized and its complexation behavior toward Cu2+ ions investigated. The ligand 6 has been characterized by spectroscopic methods, and a molecular structure of a corresponding Cu(II) complex has been elucidated by single-crystal X-ray analysis. The suitability of 6 for conjugation to peptide substrates has been shown by amide coupling of 6 to the stabilized derivative of bombesin (BN), beta Ala-beta Ala-[Cha13, Nle14]BN(7-14), to give the conjugate 8. The free ligand 6 and the bioconjugate 8 were labeled with 64Cu2+, and the resulting complexes, 64Cu subset6 and 64Cu subset8 , were found to be stable in the presence of a large excess of a competing ligand (cyclam) or copper-seeking superoxide dismutase (SOD), as well as in rat plasma. Biodistribution studies of 64Cu subset8 in Wistar rats showed a high activity uptake into the pancreas (5.76 +/- 0.25 SUV, 5 min p.i.; 3.93 +/- 0.25 SUV, 1 h p.i.), which is the organ with high levels of gastrin-releasing peptide receptor (GRPR). This receptor is overexpressed in a large number of breast and prostate carcinomas. The novel 64Cu subset6 complex had a dominating influence on the nonspecific activity biodistribution of its BN conjugate, since the distribution data of 64Cu subset6 are similar to those of 64Cu subset8 . The 64Cu complexes exhibited a low activity accumulation in the liver tissue and an extensive renal clearance, which was distinctively different to the biodistribution of 64CuCl 2, suggesting that 64Cu subset6 does not undergo significant demetalation, but rather exhibits high in vivo stability. PMID:18254581

  10. Site-Specific Bioconjugation of an Organometallic Electron Mediator to an Enzyme with Retained Photocatalytic Cofactor Regenerating Capacity and Enzymatic Activity

    Directory of Open Access Journals (Sweden)

    Sung In Lim

    2015-04-01

    Full Text Available Photosynthesis consists of a series of reactions catalyzed by redox enzymes to synthesize carbohydrates using solar energy. In order to take the advantage of solar energy, many researchers have investigated artificial photosynthesis systems mimicking the natural photosynthetic enzymatic redox reactions. These redox reactions usually require cofactors, which due to their high cost become a key issue when constructing an artificial photosynthesis system. Combining a photosensitizer and an Rh-based electron mediator (RhM has been shown to photocatalytically regenerate cofactors. However, maintaining the high concentration of cofactors available for efficient enzymatic reactions requires a high concentration of the expensive RhM; making this process cost prohibitive. We hypothesized that conjugation of an electron mediator to a redox enzyme will reduce the amount of electron mediators necessary for efficient enzymatic reactions. This is due to photocatalytically regenerated NAD(PH being readily available to a redox enzyme, when the local NAD(PH concentration near the enzyme becomes higher. However, conventional random conjugation of RhM to a redox enzyme will likely lead to a substantial loss of cofactor regenerating capacity and enzymatic activity. In order to avoid this issue, we investigated whether bioconjugation of RhM to a permissive site of a redox enzyme retains cofactor regenerating capacity and enzymatic activity. As a model system, a RhM was conjugated to a redox enzyme, formate dehydrogenase obtained from Thiobacillus sp. KNK65MA (TsFDH. A RhM-containing azide group was site-specifically conjugated to p-azidophenylalanine introduced to a permissive site of TsFDH via a bioorthogonal strain-promoted azide-alkyne cycloaddition and an appropriate linker. The TsFDH-RhM conjugate exhibited retained cofactor regenerating capacity and enzymatic activity.

  11. Different patterns of nuclear and mitochondrial penetration by the G3 PAMAM dendrimer and its biotin–pyridoxal bioconjugate BC-PAMAM in normal and cancer cells in vitro

    Directory of Open Access Journals (Sweden)

    Uram Ł

    2015-09-01

    Full Text Available Łukasz Uram,1 Magdalena Szuster,1 Aleksandra Filipowicz,2 Krzysztof Gargasz,3 Stanisław Wołowiec,3 Elżbieta Wałajtys-Rode4 1Bioorganic Chemistry Laboratory, Faculty of Chemistry, Rzeszow University of Technology, 2Cosmetology Department, University of Information Technology and Management in Rzeszow, 3Institute of Nursery and Health Sciences, Faculty of Medicine, University of Rzeszow, Rzeszow, 4Department of Drug Technology and Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland Abstract: The intracellular localization and colocalization of a fluorescently labeled G3 amine-terminated cationic polyamidoamine (PAMAM dendrimer and its biotin–pyridoxal (BC-PAMAM bioconjugate were investigated in a concentration-dependent manner in normal human fibroblast (BJ and squamous epithelial carcinoma (SCC-15 cell lines. After 24 hours treatment, both cell lines revealed different patterns of intracellular dendrimer accumulation depending on their cytotoxic effects. Cancer cells exhibited much higher (20-fold tolerance for native PAMAM treatment than fibroblasts, whereas BC-PAMAM was significantly toxic only for fibroblasts at 50 µM concentration. Fibroblasts accumulated the native and bioconjugated dendrimers in a concentration-dependent manner at nontoxic range of concentration, with significantly lower bioconjugate loading. After reaching the cytotoxicity level, fluorescein isothiocyanate-PAMAM accumulation remains at high, comparable level. In cancer cells, native PAMAM loading at higher, but not cytotoxic concentrations, was kept at constant level with a sharp increase at toxic concentration. Mander’s coefficient calculated for fibroblasts and cancer cells confirmed more efficient native PAMAM penetration as compared to BC-PAMAM. Significant differences in nuclear dendrimer penetration were observed for both cell lines. In cancer cells, PAMAM signals amounted to ~25%–35% of the total nuclei area at all

  12. Quantum entanglement and quantum operation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is a simple introduction to quantum entanglement and quantum operations. The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations. It includes remote state preparation by using any pure entangled states, nonlocal operation implementation using entangled states, entanglement capacity of two-qubit gates and two-qubit gates construction.

  13. Quantum-Hall quantum bits

    OpenAIRE

    Yang, S. -R. Eric; Schliemann, John; MacDonald, A. H.

    2002-01-01

    Bilayer quantum Hall systems can form collective states in which electrons exhibit spontaneous interlayer phase coherence. We discuss the possibility of using bilayer quantum dot many-electron states with this property to create two-level systems that have potential advantages as quantum bits.

  14. Quantum information. Teleporation - cryptography - quantum computer

    International Nuclear Information System (INIS)

    The following topics are dealt with: Reality in the test house, quantum teleportation, 100 years of quantum theory, the reality of quanta, interactionless quantum measurement, rules for quantum computers, quantum computers with ions, spintronics with diamond, the limits of the quantum computers, a view into the future of quantum optics. (HSI)

  15. Growth of anodic films on compound semiconductor electrodes: InP in aqueous (NH sub 4) sub 2 S

    CERN Document Server

    Buckley, D N

    2002-01-01

    Film formation on compound semiconductors under anodic conditions is discussed. The surface properties of InP electrodes were examined following anodization in a (NH sub 4) sub 2 S electrolyte. The observation of a current peak in the cyclic voltammetric curve was attributed to selective etching of the substrate and a film formation process. AFM images of samples anodized in the sulfide solution revealed surface pitting. Thicker films formed at higher potentials exhibited extensive cracking as observed by optical and electron microscopy, and this was explicitly demonstrated to occur ex situ rather than during the electrochemical treatment. The composition of the thick film was identified as In sub 2 S sub 3 by EDX and XPS. The measured film thickness varies linearly with the charge passed, and comparison between experimental thickness measurements and theoretical estimates for the thickness indicate a porosity of over 70 %. Cracking is attributed to shrinkage during drying of the highly porous film and does n...

  16. A Physics-Based Charge-Control Model for InP DHBT Including Current-Blocking Effect

    Institute of Scientific and Technical Information of China (English)

    GE Ji; JIN Zhi; SU Yong-Bo; CHENG Wei; WANG Xian-Wai; CHEN Gao-Peng; LIU Xin-Yu

    2009-01-01

    We develop a physics-based charge-control InP double heterojunction bipolar transistor model including three important effects: current blocking, mobile-charge modulation of the base-collector capacitance and velocity-field modulation in the transit time. The bias-dependent base-collector depletion charge is obtained analytically, which takes into account the mobile-charge modulation. Then, a measurement based voltage-dependent transit time formulation is implemented. As a result, over a wide range of biases, the developed model shows good agreement between the modeled and measured S-parameters and cutoff frequency. Also, the model considering current blocking effect demonstrates more accurate prediction of the output characteristics than conventional vertical bipolar inter company results.

  17. Study of electric field effect on the carrier captures rates of deep trap in p-type InP

    International Nuclear Information System (INIS)

    The electric field effect on the carrier capture cross section of deep trap has been studied. The experimental results of the H4F and H5 hole traps in p-type InP show an enhancement of the capture cross section with the increase of the applied electric field. This enhancement depends on the nature of the deep traps. Increasing the electric field from 8x106 to 2.4 x 107 V/m leads to an increase of the capture cross section of the H4F trap by a factor of 3 to 4 and of the H5 by a factor 4 to 5. A theoretical model has been suggested to explain the electric field effect on the capture cross section. This model deals with the cascade and multi-phonon processes semi-classically. (author)

  18. Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jandl, Adam, E-mail: jandl@mit.edu; Bulsara, Mayank T.; Fitzgerald, Eugene A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. Cambridge, Massachusetts 02139 (United States)

    2014-04-21

    The properties of InAs{sub x}P{sub 1−x} compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ε/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>10{sup 6}/cm{sup 2}) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 10{sup 5} cm{sup −2} for films graded from the InP lattice constant to InAs{sub 0.15}P{sub 0.85}. A model for a two-energy level dislocation nucleation system is proposed based on our results.

  19. Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates

    Science.gov (United States)

    Jandl, Adam; Bulsara, Mayank T.; Fitzgerald, Eugene A.

    2014-04-01

    The properties of InAsxP1-x compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ɛ/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>106/cm2) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 105 cm-2 for films graded from the InP lattice constant to InAs0.15P0.85. A model for a two-energy level dislocation nucleation system is proposed based on our results.

  20. Quantum Games and Quantum Discord

    CERN Document Server

    Nawaz, Ahmad

    2010-01-01

    We quantize prisoners dilemma and chicken game by our generalized quantization scheme to explore the role of quantum discord in quantum games. In order to establish this connection we use Werner-like state as an initial state of the game. In this quantization scheme measurement can be performed in entangled as well as in product basis. For the measurement in entangled basis the dilemma in both the games can be resolved by separable states with non-zero quantum discord. Similarly for product basis measurement the payoffs are quantum mechanical only for nonzero values of quantum discord.

  1. Au - Be/Ru/Au multilayer metallization as a stable ohmic contact scheme to p-type InP

    Science.gov (United States)

    Malina, V.; Moro, L.; Micheli, V.; Mojzes, I.

    1996-07-01

    An attempt has been made to improve the electrical and metallurgical stability of Au - Be alloyed contacts to moderately doped p-type InP by minimizing the thickness of the Au - Be contact layer and using an Ru layer as a new, more effective diffusion barrier between the Au - Be and a thick Au top layer. It was found that the Au - Be contact layer only 40 - 50 nm thick is sufficient to give excellent ohmic contacts with specific contact resistance values as low as 0268-1242/11/7/025/img6 and 0268-1242/11/7/025/img7 (for 0268-1242/11/7/025/img8 and 0268-1242/11/7/025/img9 respectively). When subjected to an aging test at 0268-1242/11/7/025/img10 for 50 h in 0268-1242/11/7/025/img11 gas, the 50 nm Au - Be/50 nm Ru/300 nm Au contacts alloyed at an optimum temperature of about 0268-1242/11/7/025/img12 exhibit good thermal stability and no substantial increase in the specific contact resistance. The remarkable metallurgical stability of such contacts was confirmed by secondary neutral mass spectroscopy (SNMS) in-depth profile measurements. A comparison with the previously investigated diffusion barrier metals (such as Cr, Ti, Pt, etc) shows that the Ru layer is a much better barrier against the migration of Au into the InP substrate and, at the same time, it suppresses the out-diffusion of In and P from the semiconductor.

  2. Quantum volume

    Science.gov (United States)

    Ryabov, V. A.

    2015-08-01

    Quantum systems in a mechanical embedding, the breathing mode of a small particles, optomechanical system, etc. are far not the full list of examples in which the volume exhibits quantum behavior. Traditional consideration suggests strain in small systems as a result of a collective movement of particles, rather than the dynamics of the volume as an independent variable. The aim of this work is to show that some problem here might be essentially simplified by introducing periodic boundary conditions. At this case, the volume is considered as the independent dynamical variable driven by the internal pressure. For this purpose, the concept of quantum volume based on Schrödinger’s equation in 𝕋3 manifold is proposed. It is used to explore several 1D model systems: An ensemble of free particles under external pressure, quantum manometer and a quantum breathing mode. In particular, the influence of the pressure of free particle on quantum oscillator is determined. It is shown also that correction to the spectrum of the breathing mode due to internal degrees of freedom is determined by the off-diagonal matrix elements of the quantum stress. The new treatment not using the “force” theorem is proposed for the quantum stress tensor. In the general case of flexible quantum 3D dynamics, quantum deformations of different type might be introduced similarly to monopole mode.

  3. Molecular beam epitaxy of InP single junction and InP/In0.53Ga0.47As monolithically integrated tandem solar cells using solid phosphorous source material

    International Nuclear Information System (INIS)

    This work reports the first InP solar cells, InP/In0.53Ga0.47As tandem solar cells and InP tunnel junctions to be grown using a solid phosphorous source cracker cell in a molecular beam epitaxy system. High p-type doping achieved with this system allowed for the development of InP tunnel junctions. These junctions which allow for improved current matching in subsequent monolithically integrated tandem devices also do not absorb photons which can be utilized in the InGaAs structure. Photocurrent spectral responses compared favorably to devices previously grown in a chemical beam epitaxy system. High resolution x-ray scans demonstrated good lattice matching between constituent parts of the tandem cell. AM0 efficiencies of both InP and InP/InGaAs tandem cells are reported

  4. Quantum flywheel

    Science.gov (United States)

    Levy, Amikam; Diósi, Lajos; Kosloff, Ronnie

    2016-05-01

    In this work we present the concept of a quantum flywheel coupled to a quantum heat engine. The flywheel stores useful work in its energy levels, while additional power is extracted continuously from the device. Generally, the energy exchange between a quantum engine and a quantized work repository is accompanied by heat, which degrades the charging efficiency. Specifically when the quantum harmonic oscillator acts as a work repository, quantum and thermal fluctuations dominate the dynamics. Quantum monitoring and feedback control are applied to the flywheel in order to reach steady state and regulate its operation. To maximize the charging efficiency one needs a balance between the information gained by measuring the system and the information fed back to the system. The dynamics of the flywheel are described by a stochastic master equation that accounts for the engine, the external driving, the measurement, and the feedback operations.

  5. Quantum measurement

    CERN Document Server

    Busch, Paul; Pellonpää, Juha-Pekka; Ylinen, Kari

    2016-01-01

    This is a book about the Hilbert space formulation of quantum mechanics and its measurement theory. It contains a synopsis of what became of the Mathematical Foundations of Quantum Mechanics since von Neumann’s classic treatise with this title. Fundamental non-classical features of quantum mechanics—indeterminacy and incompatibility of observables, unavoidable measurement disturbance, entanglement, nonlocality—are explicated and analysed using the tools of operational quantum theory. The book is divided into four parts: 1. Mathematics provides a systematic exposition of the Hilbert space and operator theoretic tools and relevant measure and integration theory leading to the Naimark and Stinespring dilation theorems; 2. Elements develops the basic concepts of quantum mechanics and measurement theory with a focus on the notion of approximate joint measurability; 3. Realisations offers in-depth studies of the fundamental observables of quantum mechanics and some of their measurement implementations; and 4....

  6. Quantum physics

    CERN Document Server

    Scheck, Florian

    2013-01-01

    Scheck’s Quantum Physics presents a comprehensive introductory treatment, ideally suited for a two-semester course. Part One covers the basic principles and prime applications of quantum mechanics, from the uncertainty relations to many-body systems. Part Two introduces to relativistic quantum field theory and ranges from symmetries in quantum physics to electroweak interactions. Numerous worked-out examples as well as exercises, with solutions or hints, enables the book’s use as an accompanying text for courses, and also for independent study. For both parts, the necessary mathematical framework is treated in adequate form and detail. The book ends with appendices covering mathematical fundamentals and enrichment topics, plus selected biographical notes on pioneers of quantum mechanics and quantum field theory. The new edition was thoroughly revised and now includes new sections on quantization using the path integral method and on deriving generalized path integrals for bosonic and fermionic fields.

  7. Quantum gravity

    International Nuclear Information System (INIS)

    This book discusses the state of the art of quantum gravity, quantum effects in cosmology, quantum black-hole physics, recent developments in supergravity, and quantum gauge theories. Topics considered include the problems of general relativity, pregeometry, complete cosmological theories, quantum fluctuations in cosmology and galaxy formation, a new inflationary universe scenario, grand unified phase transitions and the early Universe, the generalized second law of thermodynamics, vacuum polarization near black holes, the relativity of vacuum, black hole evaporations and their cosmological consequences, currents in supersymmetric theories, the Kaluza-Klein theories, gauge algebra and quantization, and twistor theory. This volume constitutes the proceedings of the Second Seminar on Quantum Gravity held in Moscow in 1981

  8. Quantum flights

    OpenAIRE

    Fateev, Evgeny G.

    2013-01-01

    The principles of quantum motors based on Casimir platforms (thin-film nanostructures are at issue) are discussed in plain language. The generation of quantum propulsion is caused by the noncompensated integral action of virtual photon momenta upon a configuration unit cell in the platform. The cells in a Casimir platform should be situated in a certain order with optimal geometric parameters. The evaluation of the quantum propulsion shows that, for example, ten square meters of ideal Casimir...

  9. Quantum Cryptography

    OpenAIRE

    Hughes, Richard J.; Alde, D. M.; Dyer, P.; Luther, G. G.; Morgan, G. L.; Schauer, M

    1995-01-01

    Quantum cryptography is a new method for secret communications offering the ultimate security assurance of the inviolability of a Law of Nature. In this paper we shall describe the theory of quantum cryptography, its potential relevance and the development of a prototype system at Los Alamos, which utilises the phenomenon of single-photon interference to perform quantum cryptography over an optical fiber communications link.

  10. Effect of bismuth surfactant on InP-based highly strained InAs/InGaAs triangular quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y.; Zhang, Y. G., E-mail: ygzhang@mail.sim.ac.cn; Chen, X. Y.; Xi, S. P.; Du, B.; Ma, Y. J. [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-23

    We report the effect of Bi surfactant on the properties of highly strained InAs/InGaAs triangular quantum wells grown on InP substrates. Reduced surface roughness, improved heterostructure interfaces and enhanced photoluminescence intensity at 2.2 μm are observed by moderate Bi-mediated growth. The nonradiative processes are analysed based on temperature-dependent photoluminescence. It is confirmed that Bi incorporation is insignificant in the samples, whereas excessive Bi flux during the growth results in deteriorated performance. The surfactant effect of Bi is promising to improve InP-based highly strained structures while the excess of Bi flux needs to be avoided.

  11. Effect of bismuth surfactant on InP-based highly strained InAs/InGaAs triangular quantum wells

    International Nuclear Information System (INIS)

    We report the effect of Bi surfactant on the properties of highly strained InAs/InGaAs triangular quantum wells grown on InP substrates. Reduced surface roughness, improved heterostructure interfaces and enhanced photoluminescence intensity at 2.2 μm are observed by moderate Bi-mediated growth. The nonradiative processes are analysed based on temperature-dependent photoluminescence. It is confirmed that Bi incorporation is insignificant in the samples, whereas excessive Bi flux during the growth results in deteriorated performance. The surfactant effect of Bi is promising to improve InP-based highly strained structures while the excess of Bi flux needs to be avoided

  12. Quantum information

    CERN Document Server

    Barnett, Stephen M

    2009-01-01

    Quantum information- the subject- is a new and exciting area of science, which brings together physics, information theory, computer science and mathematics. "Quantum Information"- the book- is based on two successful lecture courses given to advanced undergraduate and beginning postgraduate students in physics. The intention is to introduce readers at this level to the fundamental, but offer rather simple, ideas behind ground-breaking developments including quantum cryptography,teleportation and quantum computing. The text is necessarily rather mathematical in style, but the mathema

  13. Quantum information

    International Nuclear Information System (INIS)

    There is more to information than a string of ones and zeroes the ability of ''quantum bits'' to be in two states at the same time could revolutionize information technology. In the mid-1930s two influential but seemingly unrelated papers were published. In 1935 Einstein, Podolsky and Rosen proposed the famous EPR paradox that has come to symbolize the mysteries of quantum mechanics. Two years later, Alan Turing introduced the universal Turing machine in an enigmatically titled paper, On computable numbers, and laid the foundations of the computer industry one of the biggest industries in the world today. Although quantum physics is essential to understand the operation of transistors and other solid-state devices in computers, computation itself has remained a resolutely classical process. Indeed it seems only natural that computation and quantum theory should be kept as far apart as possible surely the uncertainty associated with quantum theory is anathema to the reliability expected from computers? Wrong. In 1985 David Deutsch introduced the universal quantum computer and showed that quantum theory can actually allow computers to do more rather than less. The ability of particles to be in a superposition of more than one quantum state naturally introduces a form of parallelism that can, in principle, perform some traditional computing tasks faster than is possible with classical computers. Moreover, quantum computers are capable of other tasks that are not conceivable with their classical counterparts. Similar breakthroughs in cryptography and communication followed. (author)

  14. Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

    Directory of Open Access Journals (Sweden)

    Natalia E. Mordvinova

    2015-06-01

    Full Text Available Zinc-doped InP(Zn colloidal quantum dots (QDs with narrow size distribution and low defect concentration were grown for the first time via a novel phosphine synthetic route and over a wide range of Zn doping. We report the influence of Zn on the optical properties of the obtained quantum dots. We propose a mechanism for the introduction of Zn in the QDs and show that the incorporation of Zn atoms into the InP lattice leads to the formation of Zn acceptor levels and a luminescence tail in the red region of the spectra. Using photochemical etching with HF, we confirmed that the Zn dopant atoms are situated inside the InP nanoparticles. Moreover, doping with Zn is accompanied with the coverage of the QDs by a zinc shell. During the synthesis Zn myristate covers the QD nucleus and inhibits the particle growth. At the same time the zinc shell leads to an increase of the luminescence quantum yield through the reduction of phosphorous dangling bonds. A scenario for the growth of the colloidal InP(Zn QDs was proposed and discussed.

  15. Quantum Networks for Generating Arbitrary Quantum States

    OpenAIRE

    Kaye, Phillip; Mosca, Michele

    2004-01-01

    Quantum protocols often require the generation of specific quantum states. We describe a quantum algorithm for generating any prescribed quantum state. For an important subclass of states, including pure symmetric states, this algorithm is efficient.

  16. Dissipative quantum computing with open quantum walks

    Energy Technology Data Exchange (ETDEWEB)

    Sinayskiy, Ilya; Petruccione, Francesco [National Institute for Theoretical Physics and Quantum Research Group, School of Chemistry and Physics, University of KwaZulu-Natal, Durban (South Africa)

    2014-12-04

    An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.

  17. Quantum information and computation

    OpenAIRE

    Bub, Jeffrey

    2005-01-01

    This article deals with theoretical developments in the subject of quantum information and quantum computation, and includes an overview of classical information and some relevant quantum mechanics. The discussion covers topics in quantum communication, quantum cryptography, and quantum computation, and concludes by considering whether a perspective in terms of quantum information sheds new light on the conceptual problems of quantum mechanics.

  18. Quantum physics without quantum philosophy

    International Nuclear Information System (INIS)

    Integrates and comments on the authors' seminal papers in the field. Emphasizes the natural way in which quantum phenomena emerge from the Bohmian picture. Helps to answer many of the objections raised to Bohmian quantum mechanics. Useful overview and summary for newcomers and students. It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schroedinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  19. Quantum physics without quantum philosophy

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Detlef [Muenchen Univ. (Germany). Mathematisches Inst.; Goldstein, Sheldon [Rutgers State Univ., Piscataway, NJ (United States). Dept. of Mathematics; Zanghi, Nino [Genova Univ. (Italy); Istituto Nazionale Fisica Nucleare, Genova (Italy)

    2013-02-01

    Integrates and comments on the authors' seminal papers in the field. Emphasizes the natural way in which quantum phenomena emerge from the Bohmian picture. Helps to answer many of the objections raised to Bohmian quantum mechanics. Useful overview and summary for newcomers and students. It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schroedinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  20. Quantum Schubert polynomials and quantum Schur functions

    OpenAIRE

    Kirillov, Anatol N.

    1997-01-01

    We introduce the quantum multi-Schur functions, quantum factorial Schur functions and quantum Macdonald polynomials. We prove that for restricted vexillary permutations the quantum double Schubert polynomial coincides with some quantum multi-Schur function and prove a quantum analog of the Nagelsbach-Kostka and Jacobi-Trudi formulae for the quantum double Schubert polynomials in the case of Grassmannian permutations. We prove, also, an analog of the Billey-Jockusch-Stanley formula for quantum...

  1. Quantum entanglement and quantum operation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is a simple introduction to quantum entanglement and quantum operations.The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations.It includes remote state preparation by using any pure entangled states,nonlocal operation implementation using entangled states,entanglement capacity of two-qubit gates and two-qubit gates construction.

  2. Quantum learning without quantum memory

    OpenAIRE

    Sentís, G.; Calsamiglia, J.; Muñoz-Tapia, R; Bagan, E.

    2012-01-01

    A quantum learning machine for binary classification of qubit states that does not require quantum memory is introduced and shown to perform with the minimum error rate allowed by quantum mechanics for any size of the training set. This result is shown to be robust under (an arbitrary amount of) noise and under (statistical) variations in the composition of the training set, provided it is large enough. This machine can be used an arbitrary number of times without retraining. Its required cla...

  3. Quantum group and quantum symmetry

    International Nuclear Information System (INIS)

    This is a self-contained review on the theory of quantum group and its applications to modern physics. A brief introduction is given to the Yang-Baxter equation in integrable quantum field theory and lattice statistical physics. The quantum group is primarily introduced as a systematic method for solving the Yang-Baxter equation. Quantum group theory is presented within the framework of quantum double through quantizing Lie bi-algebra. Both the highest weight and the cyclic representations are investigated for the quantum group and emphasis is laid on the new features of representations for q being a root of unity. Quantum symmetries are explored in selected topics of modern physics. For a Hamiltonian system the quantum symmetry is an enlarged symmetry that maintains invariance of equations of motion and allows a deformation of the Hamiltonian and symplectic form. The configuration space of the integrable lattice model is analyzed in terms of the representation theory of quantum group. By means of constructing the Young operators of quantum group, the Schroedinger equation of the model is transformed to be a set of coupled linear equations that can be solved by the standard method. Quantum symmetry of the minimal model and the WZNW model in conformal field theory is a hidden symmetry expressed in terms of screened vertex operators, and has a deep interplay with the Virasoro algebra. In quantum group approach a complete description for vibrating and rotating diatomic molecules is given. The exact selection rules and wave functions are obtained. The Taylor expansion of the analytic formulas of the approach reproduces the famous Dunham expansion. (author). 133 refs, 20 figs

  4. Dependence of current-voltage characteristics of pseudomorphic AlAs/In0.53Ga0.47As/InAs resonant tunnelling diodes on quantum well widths

    Institute of Scientific and Technical Information of China (English)

    Zhang Yang; Zhang Yu; Zeng Yi-Ping

    2008-01-01

    This paper studies the dependence of Ⅰ - Ⅴ characteristics on quantum well widths in AlAs/In0.53Ga0.47As and AlAs/In0.53Ga0.47As/InAs resonant tunnelling structures grown on InP substrates. It shows that the peak and the valley current density in the negative differential resistance region are closely related with quantum well width. The measured peak current density, valley current densities and peak-to-valley current ratio of resonant tunnelling diodes are continually decreasing with increasing well width.

  5. Dependence of current–voltage characteristics of pseudomorphic AlAs/In0.53Ga0.47As/InAs resonant tunnelling diodes on quantum well widths

    International Nuclear Information System (INIS)

    This paper studies the dependence of I – V characteristics on quantum well widths in AlAs/In0.50.47As and AlAs/In0.53Ga0.47As/InAs resonant tunnelling structures grown on InP substrates. It shows that the peak and the valley current density in the negative differential resistance region are closely related with quantum well width. The measured peak current density, valley current densities and peak-to-valley current ratio of resonant tunnelling diodes are continually decreasing with increasing well width. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. A simple nonradioactive method for the determination of the binding affinities of antibodies induced by hapten bioconjugates for drugs of abuse.

    Science.gov (United States)

    Torres, Oscar B; Antoline, Joshua F G; Li, Fuying; Jalah, Rashmi; Jacobson, Arthur E; Rice, Kenner C; Alving, Carl R; Matyas, Gary R

    2016-02-01

    The accurate analytical measurement of binding affinities of polyclonal antibody in sera to heroin, 6-acetylmorphine (6-AM), and morphine has been a challenging task. A simple nonradioactive method that uses deuterium-labeled drug tracers and equilibrium dialysis (ED) combined with ultra performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) to measure the apparent dissociation constant (K d) of antibodies to 6-AM and morphine is described. The method can readily detect antibodies with K d in the low nanomolar range. Since heroin is rapidly degraded in sera, esterase inhibitors were included in the assay, greatly reducing heroin hydrolysis. MS/MS detection directly measured the heroin in the assay after overnight ED, thereby allowing the quantitation of % bound heroin in lieu of K d as an alternative measurement to assess heroin binding to polyclonal antibody sera. This is the first report that utilizes a solution-based assay to quantify heroin-antibody binding without being confounded by the presence of 6-AM and morphine and to measure K d of polyclonal antibody to 6-AM. Hapten surrogates 6-AcMorHap, 6-PrOxyHap, MorHap, DiAmHap, and DiPrOxyHap coupled to tetanus toxoid (TT) were used to generate high affinity antibodies to heroin, 6-AM, and morphine. In comparison to competition ED-UPLC/MS/MS which gave K d values in the nanomolar range, the commonly used competition enzyme-linked immunosorbent assay (ELISA) measured the 50% inhibition concentration (IC50) values in the micromolar range. Despite the differences in K d and IC50 values, similar trends in affinities of hapten antibodies to heroin, 6-AM, and morphine were observed by both methods. Competition ED-UPLC/MS/MS revealed that among the five TT-hapten bioconjugates, TT-6-AcMorHap and TT-6-PrOxyHap induced antibodies that bound heroin, 6-AM, and morphine. In contrast, TT-MorHap induced antibodies that poorly bound heroin, while TT-DiAmHap and TT-DiPrOxyHap induced antibodies either did not

  7. Calculated performance of p(+)n InP solar cells with In(0.52)Al(0.48)As window layers

    Science.gov (United States)

    Jain, R. K.; Landis, G. A.

    1991-01-01

    The performance of indium phosphide solar cells with lattice matched wide band-gap In(0.52)Al(0.48)As window layers was calculated using the PC-1D computer code. The conversion efficiency of p(+)n InP solar cells is improved significantly by the window layer. No improvement is seen for n(+)p structures. The improvement in InP cell efficiency was studied as a function of In(0.52)Al(0.48)As layer thickness. The use of the window layer improves both the open circuit voltage and short circuit current.For a typical In(0.52)Al(0.48)As window layer thickness of 20 nm, the cell efficiency improves in excess of 27 percent to a value of 18.74 percent.

  8. Evidence for two distinct defects contributing to the H4 deep-level transient spectroscopy peak in electron-irradiated InP

    Science.gov (United States)

    Massarani, B.; Awad, F. G.; Kaaka, M.; Darwich, R.

    1998-12-01

    Deep-level transient spectroscopy (DLTS) has been used to study the dominant deep-level H4 produced in InP by electron irradiation. The characteristics of the H4 peak in Zn-doped InP has been studied as a function of pulse duration (tp) before and after annealing. Our results show that at least two traps contribute to the H4 peak: one is a fast trap (labeled H4F) and the other is a slow trap (labeled H4S). This is shown through several results concerning the activation energy, the capture cross section, the full width at half-maximum, and the peak temperature shift. It is shown that both traps are irradiation defects created in the P sublattice.

  9. Evidence for two distinct defects contributing to the H4 deep-level transient spectroscopy peak in electron-irradiated InP

    International Nuclear Information System (INIS)

    Deep-level transient spectroscopy (DLTS) has been used to study the dominant deep-level H4 produced in InP by electron irradiation. The characteristics of the H4 peak in Zn-doped Inp has been studied as a function of pulse duration (tp) before and after annealing. The results show that at least two traps contribute to the H4 peak: one is a fast trap (labeled H4f) and the other is a show trap (labeled H4s). This is show through several results concerning the activation energy, the capture cross section, the full width at half-maximum, and the peak temperature shift. It is shown that both traps are irradiation defects created in P sublattice. (authors)

  10. Ab initio calculations of polarization, piezoelectric constants, and elastic constants of InAs and InP in the wurtzite phase

    Energy Technology Data Exchange (ETDEWEB)

    Hajlaoui, C., E-mail: hajlaouic@yahoo.fr; Pedesseau, L. [Université Européenne de Bretagne (France); Raouafi, F.; Ben Cheikh Larbi, F. [Université de Carthage, Laboratoire de Physico-Chimie, des Microstructures et des Microsystémes, Institut Préparatoire aux Études Scientifiques et Techniques (Tunisia); Even, J.; Jancu, J.-M. [Université Européenne de Bretagne (France)

    2015-08-15

    We report first-principle density functional calculations of the spontaneous polarization, piezoelectric stress constants, and elastic constants for the III–V wurtzite structure semiconductors InAs and InP. Using the density functional theory implemented in the VASP code, we obtain polarization values–0.011 and–0.013 C/m{sup 2}, and piezoelectric constants e{sub 33} (e{sub 31}) equal to 0.091 (–0.026) and 0.012 (–0.081) C/m{sup 2} for structurally relaxed InP and InAs respectively. These values are consistently smaller than those of nitrides. Therefore, we predict a smaller built-in electric field in such structures.

  11. Multiple-Scattering of Near-Edge x-ray Absorption Fine Structure of Sulphur-Passivated InP(100) Surface

    Institute of Scientific and Technical Information of China (English)

    曹松; 唐景昌; 沈少来; 陈更生; 马丹

    2003-01-01

    We use the multiple-scattering cluster method to calculate the sulphur 1s near-edge x-ray absorption fine structure (NEXAFS) of S-passivated InP(100) surface. The physical origins of the resonances in the NEXAFS have been unveiled. It is shown that the most important resonance is attributed to the photoelectron scattering between the central sulphur and the nearest indium atoms. The studies show that two S-S dimers with the bond lengths of 2.05 A and 3.05 A coexist in the surface, meanwhile the bridge and antibridge site adsorption of single S could not be ruled out. We support the scanning tunnelling microscopy result that the S-passivated InP(100) surface exhibits significant disorder.

  12. Quantum Physics Without Quantum Philosophy

    CERN Document Server

    Dürr, Detlef; Zanghì, Nino

    2013-01-01

    It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schrödinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  13. Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

    Energy Technology Data Exchange (ETDEWEB)

    Lindskog, M., E-mail: martin.lindskog@teorfys.lu.se; Wacker, A. [Mathematical Physics, Lund University, Box 118, 22100 Lund (Sweden); Wolf, J. M.; Liverini, V.; Faist, J. [ETH Institute for Quantum Electronics, ETH-Zürich, 8093 Zürich (Switzerland); Trinite, V.; Maisons, G.; Carras, M. [III-V Lab, 1 Avenue Augustin Fresnel, 91767 Palaiseau (France); Aidam, R.; Ostendorf, R. [Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 72, 79108 Freiburg (Germany)

    2014-09-08

    We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents, agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device.

  14. Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

    International Nuclear Information System (INIS)

    We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents, agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device.

  15. Quantum information. Teleportation - cryptography - quantum computer

    International Nuclear Information System (INIS)

    The following topics are dealt with: Reality in the test facility, quantum teleportation, the reality of quanta, interaction-free quantum measurement, rules for quantum computers, quantum computers with ions, spintronics with diamond, the limits of the quantum computers, a view in the future of quantum optics. (HSI)

  16. Quantum Homogeneous Spaces as Quantum Quotient Spaces

    OpenAIRE

    Brzezinski, Tomasz

    1995-01-01

    We show that certain embeddable homogeneous spaces of a quantum group that do not correspond to a quantum subgroup still have the structure of quantum quotient spaces. We propose a construction of quantum fibre bundles on such spaces. The quantum plane and the general quantum two-spheres are discussed in detail.

  17. Quantum cosmology

    International Nuclear Information System (INIS)

    Issues arising in the application of quantum mechanics to the universe as a whole are discussed. The inevitable need for a theory of initial conditions in making quantum mechanical predictions is emphasized and some proposals for theories of initial conditions are described. (author)

  18. Quantum Theory

    CERN Document Server

    Manning, Phillip

    2011-01-01

    The study of quantum theory allowed twentieth-century scientists to examine the world in a new way, one that was filled with uncertainties and probabilities. Further study also led to the development of lasers, the atomic bomb, and the computer. This exciting new book clearly explains quantum theory and its everyday uses in our world.

  19. The infuence of different interfaces on electrical and optical characteristics of Te doped ALGaAsSB/ALAsSB Bragg Mirrors on InP

    Directory of Open Access Journals (Sweden)

    Jean C Harmand

    2008-08-01

    Full Text Available The electrical and optical properties of non-doped and Te doped 6.5 periods AlGaAsSb/AlAsSb Bragg mirrors on InP grown by MBE with different types of interfaces between ternary and quaternary layers are reported. The techniques employed were photoluminescence, refectivity and IxV measurements. The digital alloy gradient interface seems to be the best alternative to optimize conduction without significant refectivity losses.

  20. Experimental determination of the hole capture kinetics of H4F deep trap in electron-irradiated highly doped p-type InP

    International Nuclear Information System (INIS)

    The hole capture kinetics of the main trap H4F in electron-irradiated p-type InP has been investigated by experimentally determining the exponential and nonexponential parts. The contribution of the slow part of the total kinetics is about 30% in our samples. An indication to a possible capture rate enhancement due to the electric field in the space-charge region is pointed out