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Sample records for subcritical assemblies controlled

  1. Subcritical nuclear assembly

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    A Subcritical Nuclear Assembly is a device where the nuclear-fission chain reaction is initiated and maintained using an external neutron source. It is a valuable educational and research tool where in a safe way many reactor parameters can be measured. Here, we have used the Wigner-Seitz method in the six-factor formula to calculate the effective multiplication factor of a subcritical nuclear reactor Nuclear Chicago model 9000. This reactor has approximately 2500 kg of natural uranium heterogeneously distributed in slugs. The reactor uses a {sup 239}PuBe neutron source that is located in the center of an hexagonal array. Using Monte Carlo methods, with the MCNP5 code, a three-dimensional model of the subcritical reactor was designed to estimate the effective multiplication factor, the neutron spectra, the total and thermal neutron fluences along the radial and axial axis. With the neutron spectra in two locations outside the reactor the ambient dose equivalent were estimated. (Author)

  2. Modeling of Parameters of Subcritical Assembly SAD

    CERN Document Server

    Petrochenkov, S; Puzynin, I

    2005-01-01

    The accepted conceptual design of the experimental Subcritical Assembly in Dubna (SAD) is based on the MOX core with a nominal unit capacity of 25 kW (thermal). This corresponds to the multiplication coefficient $k_{\\rm eff} =0.95$ and accelerator beam power 1 kW. A subcritical assembly driven with the existing 660 MeV proton accelerator at the Joint Institute for Nuclear Research has been modelled in order to make choice of the optimal parameters for the future experiments. The Monte Carlo method was used to simulate neutron spectra, energy deposition and doses calculations. Some of the calculation results are presented in the paper.

  3. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  4. Design, Development and Installation of Jordan Subcritical Assembly

    OpenAIRE

    Ned Xoubi

    2013-01-01

    Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA) is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 ...

  5. Design, Development and Installation of Jordan Subcritical Assembly

    Directory of Open Access Journals (Sweden)

    Ned Xoubi

    2013-01-01

    Full Text Available Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 mm pitch. The fuel rods are based on PWR fuel structural pattern type, made of uranium oxide (UO2 with 3.4 wt% 235U enrichment in zirconium alloy (Zr-4 cladding. Design, optimization, and verification were performed using MCNP5 nuclear code; the computed effective multiplication factor is 0.95923. The JSA is designed to fulfill the training needs of students and is equipped to perform all of the fundamental experiments required for a typical nuclear engineering university program. This paper presents the design, development, modeling, core analysis, and utilization of Jordan’s first nuclear facility and why this simplified low cost reactor presents an attractive choice to fulfill the preliminary experimental needs of nuclear engineering education in developing countries.

  6. Research Programme for the 660 Mev Proton Accelerator Driven MOX-Plutonium Subcritical Assembly

    CERN Document Server

    Barashenkov, V S; Buttseva, G L; Dudarev, S Yu; Polanski, A; Puzynin, I V; Sissakian, A N

    2000-01-01

    The paper presents a research programme of the Experimental Acclerator Driven System (ADS), which employs a subcritical assembly and a 660 MeV proton acceletator operating at the Laboratory of Nuclear Problems of the JINR, Dubna. MOX fuel (25% PuO_2 + 75% UO_2) designed for the BN-600 reactor use will be adopted for the core of the assembly. The present conceptual design of the experimental subcritical assembly is based on a core of a nominal unit capacity of 15 kW (thermal). This corresponds to the multiplication coefficient k_eff = 0.945, energetic gain G = 30 and the accelerator beam power 0.5 kW.

  7. Influence of moderator to fuel ratio (MFR) on burning thorium in a subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowski, Andrzej, E-mail: andrzej.wojciechowski@ncbj.gov.pl [National Center for Nuclear Research, Otwock-Swierk (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2014-10-15

    The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical reactor assembly is presented as a function of MFR, burnup, power density (PD) and fissile concentration. The calculated model is based on subcritical assembly which makes configuration of fuel rods and volumes of moderator and coolant changes possible. This comfortable assembly enables investigation of CR in a thorium cycle for different value of MFR. Additionally, the calculation results of U-233 saturation concentration are explained by mathematical model. The value of MFR main influences the saturation concentration of U-233 and fissile and the fissile concentration dependence of CR. The saturation value of CR is included in the range CR ∈ (0.911, 0.966) and is a slowly increasing function of MFR. The calculations were done with a MCNPX 2.7 code.

  8. Criticality Safety Evaluation of the LLNL Inherently Safe Subcritical Assembly (ISSA)

    Energy Technology Data Exchange (ETDEWEB)

    Percher, Catherine [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-06-19

    The LLNL Nuclear Criticality Safety Division has developed a training center to illustrate criticality safety and reactor physics concepts through hands-on experimental training. The experimental assembly, the Inherently Safe Subcritical Assembly (ISSA), uses surplus highly enriched research reactor fuel configured in a water tank. The training activities will be conducted by LLNL following the requirements of an Integration Work Sheet (IWS) and associated Safety Plan. Students will be allowed to handle the fissile material under the supervision of LLNL instructors. This report provides the technical criticality safety basis for instructional operations with the ISSA experimental assembly.

  9. Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the time is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.

  10. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio [Universidad Simón Bolívar, Nuclear Physics Laboratory, Apdo 89000, Caracas 1080A (Venezuela, Bolivarian Republic of); Davila, Jesus [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  11. Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division

    2008-10-22

    One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.

  12. Radioactive isotope production for medical applications using Kharkov electron driven subcritical assembly facility.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, Y.; Nuclear Engineering Division

    2007-05-15

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an accelerator driven subcritical assembly. The main functions of the subcritical assembly are the medical isotope production, neutron thereby, and the support of the Ukraine nuclear industry. Reactor physics experiments and material research will be carried out using the capabilities of this facility. The United States of America and Ukraine have started collaboration activity for developing a conceptual design for this facility with low enrichment uranium (LEU) fuel. Different conceptual designs are being developed based on the facility mission and the engineering requirements including nuclear physics, neutronics, heat transfer, thermal hydraulics, structure, and material issues. Different fuel designs with LEU and reflector materials are considered in the design process. Safety, reliability, and environmental considerations are included in the facility conceptual design. The facility is configured to accommodate future design improvements and upgrades. This report is a part of the Argonne National Laboratory Activity within this collaboration for developing and characterizing the subcritical assembly conceptual design. In this study, the medical isotope production function of the Kharkov facility is defined. First, a review was carried out to identify the medical isotopes and its medical use. Then a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Finally, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and irradiation location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes were considered and all transmutation channels are used including (n,{gamma}), (n,2n), (n,p), and ({gamma},n). In the second part

  13. Monte Carlo modeling and analyses of YALINA-booster subcritical assembly part 1: analytical models and main neutronics parameters.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Nuclear Engineering Division

    2008-09-11

    This study was carried out to model and analyze the YALINA-Booster facility, of the Joint Institute for Power and Nuclear Research of Belarus, with the long term objective of advancing the utilization of accelerator driven systems for the incineration of nuclear waste. The YALINA-Booster facility is a subcritical assembly, driven by an external neutron source, which has been constructed to study the neutron physics and to develop and refine methodologies to control the operation of accelerator driven systems. The external neutron source consists of Californium-252 spontaneous fission neutrons, 2.45 MeV neutrons from Deuterium-Deuterium reactions, or 14.1 MeV neutrons from Deuterium-Tritium reactions. In the latter two cases a deuteron beam is used to generate the neutrons. This study is a part of the collaborative activity between Argonne National Laboratory (ANL) of USA and the Joint Institute for Power and Nuclear Research of Belarus. In addition, the International Atomic Energy Agency (IAEA) has a coordinated research project benchmarking and comparing the results of different numerical codes with the experimental data available from the YALINA-Booster facility and ANL has a leading role coordinating the IAEA activity. The YALINA-Booster facility has been modeled according to the benchmark specifications defined for the IAEA activity without any geometrical homogenization using the Monte Carlo codes MONK and MCNP/MCNPX/MCB. The MONK model perfectly matches the MCNP one. The computational analyses have been extended through the MCB code, which is an extension of the MCNP code with burnup capability because of its additional feature for analyzing source driven multiplying assemblies. The main neutronics parameters of the YALINA-Booster facility were calculated using these computer codes with different nuclear data libraries based on ENDF/B-VI-0, -6, JEF-2.2, and JEF-3.1.

  14. (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

    OpenAIRE

    Bielewicz Marcin; Kilim Stanisław; Strugalska-Gola Elżbieta; Szuta Marcin; Wojciechowski Andrzej; Tyutyunnikov Sergey; Prokofiev Alexander; Passoth Elke

    2017-01-01

    Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project “Energy and Transmutation of Radioactive Wastes” (E&T – RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurement...

  15. Odd-number theorem: Optical feedback control at a subcritical Hopf bifurcation in a semiconductor laser

    Science.gov (United States)

    Schikora, S.; Wünsche, H.-J.; Henneberger, F.

    2011-02-01

    A subcritical Hopf bifurcation is prepared in a multisection semiconductor laser. In the free-running state, hysteresis is absent due to noise-induced escape processes. The missing branches are recovered by stabilizing them against noise through application of phase-sensitive noninvasive delayed optical feedback control. The same type of control is successfully used to stabilize the unstable pulsations born in the Hopf bifurcation. This experimental finding represents an optical counterexample to the so-called odd-number limitation of delayed feedback control. However, as a leftover of the limitation, the domains of control are extremely small.

  16. Optimum design and criticality safety of a beam-shaping assembly with an accelerator-driven subcritical neutron multiplier for boron neutron capture therapies.

    Science.gov (United States)

    Hiraga, F

    2015-12-01

    The beam-shaping assembly for boron neutron capture therapies with a compact accelerator-driven subcritical neutron multiplier was designed so that an epithermal neutron flux of 1.9×10(9) cm(-2) s(-1) at the treatment position was generated by 5 MeV protons in a beam current of 2 mA. Changes in the atomic density of (135)Xe in the nuclear fuel due to the operation of the beam-shaping assembly were estimated. The criticality safety of the beam-shaping assembly in terms of Xe poisoning is discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Subcritical Multiplication Parameters of the Accelerator-Driven System with 100 MeV Protons at the Kyoto University Critical Assembly

    OpenAIRE

    Jae-Yong Lim; Cheol Ho Pyeon; Takahiro Yagi; Tsuyoshi Misawa

    2012-01-01

    Basic experiments on the accelerator-driven system (ADS) at the Kyoto University Critical Assembly are carried out by combining a solid-moderated and -reflected core with the fixed-field alternating gradient accelerator. The reaction rates are measured by the foil activation method to obtain the subcritical multiplication parameters. The numerical calculations are conducted with the use of MCNPX and JENDL/HE-2007 to evaluate the reaction rates of activation foils set in the core region and at...

  18. (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly "QUINTA"

    Science.gov (United States)

    Bielewicz, Marcin; Kilim, Stanisław; Strugalska-Gola, Elżbieta; Szuta, Marcin; Wojciechowski, Andrzej; Tyutyunnikov, Sergey; Prokofiev, Alexander; Passoth, Elke

    2017-09-01

    Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project "Energy and Transmutation of Radioactive Wastes" (E&T - RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurements were carried out at The Svedberg laboratory (TSL) in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

  19. (n,xn cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

    Directory of Open Access Journals (Sweden)

    Bielewicz Marcin

    2017-01-01

    Full Text Available Study of the deep subcritical systems (QUINTA using relativistic beams is performed within the project “Energy and Transmutation of Radioactive Wastes” (E&T – RAW. The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON. We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn reactions in yttrium (Y-89 foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn cross section measurements were carried out at The Svedberg laboratory (TSL in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

  20. Subcritical Multiplication Parameters of the Accelerator-Driven System with 100 MeV Protons at the Kyoto University Critical Assembly

    Directory of Open Access Journals (Sweden)

    Jae-Yong Lim

    2012-01-01

    Full Text Available Basic experiments on the accelerator-driven system (ADS at the Kyoto University Critical Assembly are carried out by combining a solid-moderated and -reflected core with the fixed-field alternating gradient accelerator. The reaction rates are measured by the foil activation method to obtain the subcritical multiplication parameters. The numerical calculations are conducted with the use of MCNPX and JENDL/HE-2007 to evaluate the reaction rates of activation foils set in the core region and at the location of the target. Here, a comparison between the measured and calculated eigenvalues reveals a relative difference of around 10% in C/E values. A special mention is made of the fact that the reaction rate analyses in the subcritical systems demonstrate apparently the actual effect of moving the tungsten target into the core on neutron multiplication. A series of further ADS experiments with 100 MeV protons needs to be carried out to evaluate the accuracy of subcritical multiplication parameters.

  1. Advanced gray rod control assembly

    Science.gov (United States)

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  2. Hand Controller Assembly

    Science.gov (United States)

    Bandera, Pablo (Inventor); Buchele, Paul (Inventor)

    2015-01-01

    A user input device for a vehicular electrical system is provided. The user input device includes a handle sized and shaped to be gripped by a human hand and a gimbal assembly within the handle. The gimbal assembly includes a first gimbal component, a second gimbal component coupled to the first gimbal component such that the second gimbal component is rotatable relative to the first gimbal component about a first axis, and a third gimbal component coupled to the second gimbal component such that the third gimbal component is rotatable relative to the second gimbal component about a second axis.

  3. Geochemical controls on the kinetics of quartz fracture at subcritical tensile stresses

    Science.gov (United States)

    Dove, Patricia M.

    1995-11-01

    A new kinetic model links physical and chemical controls on the subcritical fracture kinetics of quartz from the assumption that molecular level reactions governing fracture and dissolution proceed by similar pathways. The model formulation combines fracture theory with a mechanistically based description of chemical, thermal, and tensile stress effects on reactivity in aqueous environments. Water, as a vapor or liquid, promotes rupture of Si-O bonds by end-member processes: (1) reaction of a protonated surface with molecular water and (2) reaction of hydroxyl ions at an ionized surface. In humid environments, reaction frequency is determined by water accessibility to the crack tip. In wetted environments, the relative contributions of these mechanisms are determined by bulk solution composition which affects surface ionization and sol vent-surf ace interactions. The macroscopic fracture rate law is given in meters per second by the fractional sum of these end-member reaction mechanisms per a first-order equation. Agreement of this empirical rate expression with reported measurements of quartz fracture rates suggests the model is robust. It gives a good fit to fracture rates over 6 orders of magnitude and explains increasing rates with increasing solution pH, the dependence of rate upon crystallographic direction, and thermal dependence of rate over 20° to 80°C. Findings in this study suggest that (1) fracture models based upon changes in surface free energy with solution composition are macroscopic descriptions of solvent-surface interactions and parallel the mechanistic model presented here; (2) faster fracture rates observed in basic solutions are not facilitated by decreases in the activation barrier but are due to a transition in the solvent-surface reaction to give a higher reaction frequency and (3) power law expressions applied to fracture rate versus stress intensity measurements may not have direct mechanistic significance since log-linear relations

  4. Subcritical multiplication determination studies

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P.; Goulding, C.A.

    1995-07-01

    A series of measurements and improvements to computational techniques are in progress at Los Alamos National Laboratory that are aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the apparent multiplication of the system. Such studies are being performed in order to improve the special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, etc. Improved techniques and understanding are needed since measured multiplication is not always an invariant characteristic of a subcritical system, especially if one has a system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a non-normal mode system).

  5. Monte Carlo simulation of a perturbed subcritical core

    Energy Technology Data Exchange (ETDEWEB)

    Jaradat, Mustafa K.; Park, Chang Je [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Jordan Subcritical Assembly (JSA) is designed for the purpose of education, training, and experiment research. Jordan subcritical assembly is considered Jordan's First Nuclear Facility Moving Jordan into the nuclear age. It is a teaching and training experimental facility that is designed to stay in a subcriticality A subcritical assembly is a multiplying system of nuclear fuel and moderator whose effective multiplication factor is less than unity. An extraneous source of neutron is required for the operation in order to compensate for the difference between the production rate of fission neutrons in the fuel and the rate of loss caused by absorption and leakage.

  6. Uranium Fission Track Integrator for Measurement of Energy Production in the Subcritical Uranium Blanket of Electronuclear Assembly

    CERN Document Server

    Chultem, D; Krivopustov, M I

    2001-01-01

    Using nuclear track detectors in the uranium blanket of electronuclear assembly partial fission integrals have been measured. The merit of this method lies in the fact that uranium fission integrals are determined in every points of measurement as well as in whole volume of blanket. In addition, not only measurement of neutron spectra \\Phi(E_n) but also without going into details of excitation functions: \\sigma_f^5(E_n) and \\sigma_f^8(E_n) in wide range of energies, without recourse to group averaged cross sections are not required. The method was tested in the experiment on uranium blanket of electronuclear assembly "Energy plus transmutation" calorimetry at 1.5 GeV beam from synchrophasotron (JINR).

  7. Physical controls on directed virus assembly at nanoscale chemical templates

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, C L; Chung, S; Chatterji, A; Lin, T; Johnson, J E; Hok, S; Perkins, J; De Yoreo, J

    2006-05-10

    Viruses are attractive building blocks for nanoscale heterostructures, but little is understood about the physical principles governing their directed assembly. In-situ force microscopy was used to investigate organization of Cowpea Mosaic Virus engineered to bind specifically and reversibly at nanoscale chemical templates with sub-30nm features. Morphological evolution and assembly kinetics were measured as virus flux and inter-viral potential were varied. The resulting morphologies were similar to those of atomic-scale epitaxial systems, but the underlying thermodynamics was analogous to that of colloidal systems in confined geometries. The 1D templates biased the location of initial cluster formation, introduced asymmetric sticking probabilities, and drove 1D and 2D condensation at subcritical volume fractions. The growth kinetics followed a t{sup 1/2} law controlled by the slow diffusion of viruses. The lateral expansion of virus clusters that initially form on the 1D templates following introduction of polyethylene glycol (PEG) into the solution suggests a significant role for weak interaction.

  8. Forwardly-placed firearm fire control assembly

    Energy Technology Data Exchange (ETDEWEB)

    Frickey, Steven J. (Rigby, ID)

    2001-12-22

    A firearm fire control assembly for disposition in a forwardly placed support-hand operative relationship within a firearm having a combination of a firing pin and a firearm hammer adapted to engage and fire a cartridge, a sear assembly to alternately engage and disengage the combination of the firearm hammer and firing pin, and a trigger assembly including a movable trigger mechanism that is operable to engage the sear assembly to cause the firearm hammer firing pin combination to fire the firearm, a fire control assembly including a fire control depression member and a fire control rod operably connected to the depression member, and being positioned in a forward disposition disposed within a forestock of the firearm, and the depression member adapted to be operably engaged and depressed by the user's conventional forwardly placed support hand to maneuver the fire control rod to provide firing control of the firing of the firearm.

  9. Forwardly-placed firearm fire control assembly

    Science.gov (United States)

    Frickey, Steven J.

    2001-12-22

    A firearm fire control assembly for disposition in a forwardly placed support-hand operative relationship within a firearm having a combination of a firing pin and a firearm hammer adapted to engage and fire a cartridge, a sear assembly to alternately engage and disengage the combination of the firearm hammer and firing pin, and a trigger assembly including a movable trigger mechanism that is operable to engage the sear assembly to cause the firearm hammer firing pin combination to fire the firearm, a fire control assembly including a fire control depression member and a fire control rod operably connected to the depression member, and being positioned in a forward disposition disposed within a forestock of the firearm, and the depression member adapted to be operably engaged and depressed by the user's conventional forwardly placed support hand to maneuver the fire control rod to provide firing control of the firing of the firearm.

  10. DNA controlled assembly of liposomes

    DEFF Research Database (Denmark)

    Vogel, Stefan; Jakobsen, Ulla; Simonsen, Adam Cohen

    2009-01-01

    DNA-encoding of solid nanoparticles requires surfacechemistry, which is often tedious and not generally applicable. In the present study non-covalently attached DNA are used to assemble soft nanoparticles (liposomes) in solution. This process displays remarkably sharp thermal transitions from ass...... assembled to disassembled state for which reason this method allows easy and fast detection of polynucleotides (e.g. DNA or RNA), including single nucleotide polymorphisms as well as insertions and deletions....

  11. Reactivity control assembly for nuclear reactor

    Science.gov (United States)

    Bollinger, Lawrence R.

    1984-01-01

    Reactivity control assembly for nuclear reactor comprises supports stacked above reactor core for holding control rods. Couplers associated with the supports and a vertically movable drive shaft have lugs at their lower ends for engagement with the supports.

  12. Subcritical neutron production using multiple accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, W.Y.; Jones, J.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Harmon, J.F. [Idaho State Univ., Pocatello, ID (United States)

    1994-12-31

    A subcritical neutron production technique using multiple accelerators is being developed to provide a selective alternative (for small volumes) to nuclear reactor neutron production. The concept combines the capabilities of multiple commercially-available linear accelerators and a compact subcritical assembly design to generate reactor-like thermal neutron fluxes (i.e., 10{sup 13}-10{sup 14} n/cm{sup 2}/s) in small irradiation volumes of up to 500 cm{sup 3}. In addition, fast and epithermal neutron fluxes will also be available. The neutron source utilizes radially-oriented, pulsed, electron accelerators. The subcritical neutron production assembly is in the form of a compact right-cylinder (approximately 20-cm dia.). This assembly uses an outer ring of graphite (i.e., reflector) with re-entrant holes to enable penetration of the electron beam to the internal structure which comprises of uranium as an electron convertor/neutron multiplier followed by H{sub 2}O beryllium, H{sub 2}O aluminum, and D{sub 2}O in succession toward the center. The inner-most region filled with D{sub 2}O is the central irradiation volume. The material configuration and overall design is to maximize thermal neutron fluxes in the central irradiation volume based on photoneutron/photofission and neutron multiplication processes as well as neutron transport. This assembly will be designed not to reach a nuclear critical state under any normal and/or accidental condition.

  13. Radiological characterization of spent control rod assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Lepel, E.A.; Robertson, D.E.; Thomas, C.W.; Pratt, S.L.; Haggard, D.L. [Pacific Northwest Lab., Richland, WA (United States)

    1995-10-01

    This document represents the final report of an ongoing study to provide radiological characterizations, classifications, and assessments in support of the decommissioning of nuclear power stations. This report describes the results of non-destructive and laboratory radionuclide measurements, as well as waste classification assessments, of BWR and PWR spent control rod assemblies. The radionuclide inventories of these spent control rods were determined by three separate methodologies, including (1) direct assay techniques, (2) calculational techniques, and (3) by sampling and laboratory radiochemical analyses. For the BWR control rod blade (CRB) and PWR burnable poison rod assembly (BPRA), {sup 60}Co and {sup 63}Ni, present in the stainless steel cladding, were the most abundant neutron activation products. The most abundant radionuclide in the PWR rod cluster control assembly (RCCA) was {sup 108m}Ag (130 yr halflife) produced in the Ag-In-Cd alloy used as the neutron poison. This radionuclide will be the dominant contributor to the gamma dose rate for many hundreds of years. The results of the direct assay methods agree very well ({+-}10%) with the sampling/radiochemical measurements. The results of the calculational methods agreed fairly well with the empirical measurements for the BPRA, but often varied by a factor of 5 to 10 for the CRB and the RCCA assemblies. If concentration averaging and encapsulation, as allowed by 10CFR61.55, is performed, then each of the entire control assemblies would be classified as Class C low-level radioactive waste.

  14. Mechanisms of Subcritical Cracking in Calcite

    Science.gov (United States)

    Royne, A.; Dysthe, D. K.; Bisschop, J.

    2008-12-01

    Brittle materials are characterized by a critical stress intensity factor above which they will fail catastrophically by dynamic cracking. However, it has been observed that materials can also fail at much lower stresses, through slow crack growth, often referred to as subcritical cracking. This phenomenon can take place even in vacuum, but is greatly enhanced by water and other reactive species in the environment. For a given material and environmental condition there is a systematic relationship between the crack tip velocity and the stress intensity factor. The presence of a lower stress limit to subcritical cracking has been predicted from thermodynamics but has not been firmly demonstrated experimentally. This parameter would control the long- term strength of geological materials. Subcritical cracking must necessarily be important in controlling the rock strength in near-surface processes where water and other active species are present and the displacements and stresses are low. Weathering is one example of such a process. Modelling has shown that fracture networks generated by a high degree of subcritical cracking will percolate at much lower fracture densities than purely stochastical fracture networks. This has important implications for how water can move through the crust. Understanding the mechanisms for subcritical crack growth in geological materials is also important in assessing the stability and long term performance of sequestration reservoirs for CO2 or nuclear waste. The mechanism for stress corrosion is well known for glasses and quartz. For carbonate minerals, the mechanism for subcritical crack growth has not been identified, and the only experimental studies on calcitic materials have been on polycrystalline rocks such as marble. Suggested mechanisms include stress corrosion (weakening reactions at the crack tip), preferential dissolution at the crack tip with rapid removal of dissolved species, and environmentally controlled

  15. Determination of the physical parameters of the nuclear subcritical assembly Chicago 9000 of the IPN using the Serpent code; Determinacion de los parametros fisicos del conjunto subcritico nuclear Chicago 9000 del IPN usando el codigo SERPENT

    Energy Technology Data Exchange (ETDEWEB)

    Arriaga R, L.; Del Valle G, E. [IPN, Escuela Superior de Fisica y Matematicas, Av. Instituto Politecnico Nacional s/n, U.P. Adolfo Lopez Mateos, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico); Gomez T, A. M., E-mail: guten_tag_04@hotmail.com [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2013-10-15

    For the Serpent code was developed the three-dimensional model corresponding to the nuclear subcritical assembly (S A) Chicago 9000 of the Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional (ESFM-IPN). The model includes: a) the core, formed by 312 aluminum pipes that contain 5 nuclear fuel rods (natural uranium in metallic form), b) the multi-perforated plates where they penetrate the inferior part of each pipe to be able to remain in vertical form, c) water, acting as moderator and reflector, and d) the recipient lodging to the core. The pipes arrangement is hexagonal although the transversal section of the recipient that lodges to the core is circular. The entrance file for the Serpent code was generated with the data provided by the manual of the S A use about the composition and density of the fuel rods and others obtained in direct form of the rods, as the interior and external diameter, mass and height. Of the obtained physical parameters, those more approached to that reported in the manual of the subcritical assembly are the effective multiplication factor and the reproduction factor η. The differences can be because the description of the fuel rods provided by the manual of the S A use do not correspond those that are physically in the S A core. This difference consists on the presence of a circular central channel of 1.245 diameter centimeters in each fuel rod. The fuel rods reported in the mentioned manual do not have that channel. Although the obtained results are encouraging, we want to continue improving the model to incorporate in this the detectors, defined this way by the Serpent code, which could determine the existent neutrons flux in diverse points of interest like the axial or radial aligned points and to compare these with those that are obtained in an experimental way when a generating neutrons source (Pu-Be) is introduced. Added to this effort the cross sections for each unitary cell will be determined, so that

  16. Quantum Subcritical Bubbles

    Science.gov (United States)

    Uesugi, T.; Morikawa, M.; Shiromizu, T.

    1996-08-01

    We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using a quantum statistical average. Furthermore, based on our study, we discuss implications for the dynamics of phase transitions.

  17. Reactivity control assembly for nuclear reactor. [LMFBR

    Science.gov (United States)

    Bollinger, L.R.

    1982-03-17

    This invention, which resulted from a contact with the United States Department of Energy, relates to a control mechanism for a nuclear reactor and, more particularly, to an assembly for selectively shifting different numbers of reactivity modifying rods into and out of the core of a nuclear reactor. It has been proposed heretofore to control the reactivity of a breeder reactor by varying the depth of insertion of control rods (e.g., rods containing a fertile material such as ThO/sub 2/) in the core of the reactor, thereby varying the amount of neutron-thermalizing coolant and the amount of neutron-capturing material in the core. This invention relates to a mechanism which can advantageously be used in this type of reactor control system.

  18. Electric field mediated colloidal assembly and control

    Science.gov (United States)

    Juarez, Jaime Javier

    2011-12-01

    quadrupole electrode device by guiding the dynamic evolution of a colloidal ensemble. A feedback method is used to control electric field mediated assembly based on real-time sensing and actuation single and multiple electrokinetic mechanisms. Sensing is achieved using particle tracking and order parameter computation to quantify the degree of order during the assembly process. A geometrical parameter for hexagonal close packing and radius of gyration are investigated as order parameters for quantifying condensation and crystallization. Colloidal crystal assembly and disassembly is actuated using electroosmosis and negative and positive dielectrophoresis (i.e. dipole-field interactions).

  19. Modeling of the CTEx subcritical unit using MCNPX code

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Avelino [Divisao de Defesa Quimica, Biologica e Nuclear. Centro Tecnologico do Exercito - CTEx, Guaratiba, Rio de Janeiro, RJ (Brazil); Silva, Ademir X. da, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear. Universidade Federal do Rio de Janeiro - UFRJ Centro de Tecnologia, Rio de Janeiro, RJ (Brazil); Rebello, Wilson F. [Secao de Engenharia Nuclear - SE/7 Instituto Militar de Engenharia - IME Rio de Janeiro, RJ (Brazil); Cunha, Victor L. Lassance [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The present work aims at simulating the subcritical unit of Army Technology Center (CTEx) namely ARGUS pile (subcritical uranium-graphite arrangement) by using the computational code MCNPX. Once such modeling is finished, it could be used in k-effective calculations for systems using natural uranium as fuel, for instance. ARGUS is a subcritical assembly which uses reactor-grade graphite as moderator of fission neutrons and metallic uranium fuel rods with aluminum cladding. The pile is driven by an Am-Be spontaneous neutron source. In order to achieve a higher value for k{sub eff}, a higher concentration of U235 can be proposed, provided it safely remains below one. (author)

  20. Missing Links in Antibody Assembly Control

    Directory of Open Access Journals (Sweden)

    Tiziana Anelli

    2013-01-01

    Full Text Available Fidelity of the humoral immune response requires that quiescent B lymphocytes display membrane bound immunoglobulin M (IgM on B lymphocytes surface as part of the B cell receptor, whose function is to recognize an antigen. At the same time B lymphocytes should not secrete IgM until recognition of the antigen has occurred. The heavy chains of the secretory IgM have a C-terminal tail with a cysteine instead of a membrane anchor, which serves to covalently link the IgM subunits by disulfide bonds to form “pentamers” or “hexamers.” By virtue of the same cysteine, unassembled secretory IgM subunits are recognized and retained (via mixed disulfide bonds by members of the protein disulfide isomerase family, in particular ERp44. This so-called “thiol-mediated retention” bars assembly intermediates from prematurely leaving the cell and thereby exerts quality control on the humoral immune response. In this essay we discuss recent findings on how ERp44 governs such assembly control in a pH-dependent manner, shuttling between the cisGolgi and endoplasmic reticulum, and finally on how pERp1/MZB1, possibly as a co-chaperone of GRP94, may help to overrule the thiol-mediated retention in the activated B cell to give way to antibody secretion.

  1. Controllable self-assembly of RNA dendrimers.

    Science.gov (United States)

    Sharma, Ashwani; Haque, Farzin; Pi, Fengmei; Shlyakhtenko, Lyudmila S; Evers, B Mark; Guo, Peixuan

    2016-04-01

    We report programmable self-assembly of branched, 3D globular, monodisperse and nanoscale sized dendrimers using RNA as building blocks. The central core and repeating units of the RNA dendrimer are derivatives of the ultrastable three-way junction (3WJ) motif from the bacteriophage phi29 motor pRNA. RNA dendrimers were constructed by step-wise self-assembly of modular 3WJ building blocks initiating with a single 3WJ core (Generation-0) with overhanging sticky end and proceeding in a radial manner in layers up to Generation-4. The final constructs were generated under control without any structural defects in high yield and purity, as demonstrated by gel electrophoresis and AFM imaging. Upon incorporation of folate on the peripheral branches of the RNA dendrimers, the resulting constructs showed high binding and internalization into cancer cells. RNA dendrimers are envisioned to have a major impact in targeting, disease therapy, molecular diagnostics and bioelectronics in the near future. Dendrimers are gaining importance as a carrier platform for diagnosis and therapeutics. The authors here reported building of their dendrimer molecules using RNA as building blocks. The addition of folate also allowed recognition and subsequent binding to tumor cells. This new construct may prove to be useful in many clinical settings. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. MCNP multiplication analysis of subcritical HEU experiments

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P. [Los Alamos National Lab., NM (United States); Brockhoff, R.C. [Kansas State Univ., Manhattan, KS (United States)

    1998-12-31

    A series of measurements and improvements to computational techniques was described in Ref. 1 that were aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the multiplying characteristics of the system. This methodology has been applied to a number of the bare highly enriched uranium (HEU) measurements (simulating 0.5- to 21.5-kg balls with nesting shells) of Ref. 2, demonstrating that the experimental multiplication results can be reproduced computationally with good accuracy. This capability promises to improve special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, smuggling of SNM, etc. Improved techniques and understanding are needed since traditionally measured or calculated multiplications are not always an invariant characteristic of a subcritical system, especially if one has an SNM system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a nonnormal mode system). The measurement techniques used in Refs. 1 and 2 to determine multiplication are based on the Feynman variance-to-mean method, which has been previously documented in Refs. 3 and 4 and applied successfully to normal mode systems such as plutonium and uranium spheres. These techniques have been applied to nonnormal mode problems with less success, and both Refs. 1 and 2 as well as the current paper are attempts to better understand the subcritical multiplication of such systems.

  3. Nuclear reactor shutdown control rod assembly

    Science.gov (United States)

    Bilibin, Konstantin

    1988-01-01

    A temperature responsive, self-actuated nuclear reactor shutdown control rod assembly 10. The upper end 18 of a lower drive line 17 fits within the lower end of an upper drive line 12. The lower end (not shown) of the lower drive line 17 is connected to a neutron absorber. During normal temperature conditions the lower drive line 17 is supported by detent means 22,26. When an overtemperature condition occurs thermal actuation means 34 urges ring 26 upwardly sufficiently to allow balls 22 to move radially outwardly thereby allowing lower drive line 17 to move downwardly toward the core of the nuclear reactor resulting in automatic reduction of the reactor powder.

  4. Accelerator driven sub-critical core

    Science.gov (United States)

    McIntyre, Peter M; Sattarov, Akhdiyor

    2015-03-17

    Systems and methods for operating an accelerator driven sub-critical core. In one embodiment, a fission power generator includes a sub-critical core and a plurality of proton beam generators. Each of the proton beam generators is configured to concurrently provide a proton beam into a different area of the sub-critical core. Each proton beam scatters neutrons within the sub-critical core. The plurality of proton beam generators provides aggregate power to the sub-critical core, via the proton beams, to scatter neutrons sufficient to initiate fission in the sub-critical core.

  5. System and method for controlling a combustor assembly

    Science.gov (United States)

    York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Stevenson, Christian Xavier

    2013-03-05

    A system and method for controlling a combustor assembly are disclosed. The system includes a combustor assembly. The combustor assembly includes a combustor and a fuel nozzle assembly. The combustor includes a casing. The fuel nozzle assembly is positioned at least partially within the casing and includes a fuel nozzle. The fuel nozzle assembly further defines a head end. The system further includes a viewing device configured for capturing an image of at least a portion of the head end, and a processor communicatively coupled to the viewing device, the processor configured to compare the image to a standard image for the head end.

  6. Off-Design Performances of Subcritical and Supercritical Organic Rankine Cycles in Geothermal Power Systems under an Optimal Control Strategy

    National Research Council Canada - National Science Library

    Tieyu Gao; Changwei Liu

    2017-01-01

    .... In this study, an off-design performance prediction model for geothermal ORC systems is developed according to special designs of critical components, and an optimal control strategy which regards...

  7. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Science.gov (United States)

    Sinha, Amar; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P. S.; Bishnoi, Saroj

    2015-05-01

    The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated keff of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor ks and external neutron source efficiency φ∗ in great details. Experiments with D-T neutrons are also underway.

  8. DNA controlled assembly of soft nanoparticles

    DEFF Research Database (Denmark)

    Vogel, Stefan; Simonsen, Adam Cohen; Jakobsen, Ulla

    2008-01-01

    DNA-encoding of solid nanoparticles requires surfacechemistry, which is often tedious and not generally applicable. In the present study non-covalently attached DNA are used to assemble soft nanoparticles (liposomes) in solution. This process displays remarkably sharp thermal transitions from ass...... assembled to disassembled state for which reason this method allows easy and fast detection of polynucleotides (e.g. DNA or RNA), including single nucleotide polymorphisms as well as insertions and deletions....

  9. Controlled manipulation of giant hybrid inorganic nanowire assemblies.

    Science.gov (United States)

    Ou, Fung Suong; Shaijumon, Manikoth M; Ajayan, Pulickel M

    2008-07-01

    The ultimate goal of nanotechnology is the design and fabrication of nanosize building blocks with multiple functionalities and their assembly into large-scale functional structures that can be controllably manipulated. Here we show that hybrid inorganic multisegmented nanowires, with hydrophobic carbon nanotube tails and hydrophilic metal nanowire heads, allow the assembly and manipulation of massive ordered structures in solution, reminiscent of the organic molecular micellar assembly. Further, properly designed assemblies can be manipulated using external stimuli such as magnetic field and light. The hybrid nanowires can have multiple segments including magnetic components, allowing the assembly to be manipulated by external magnetic field. The assembled structures can also be manipulated by modifying the hydrophobicity of the respective components via chemical functionalization and optical irradiation. This approach brings the concept of environment sensitive self-assembling nanomaterials closer to reality.

  10. Evaluation of reactivity monitoring techniques at the Yalina - Booster sub-critical facility

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.

    2014-07-01

    The management of long-lived radioactive wastes produced by nuclear reactors constitutes one of the main challenges of nuclear technology nowadays. A possible option for its management consists in the transmutation of long lived nuclides into shorter lived ones. Accelerator Driven Subcritical Systems (ADS) are one of the technologies in development to achieve this goal. An ADS consists in a subcritical nuclear reactor maintained in a steady state by an external neutron source driven by a particle accelerator. The interest of these systems lays on its capacity to be loaded with fuels having larger contents of minor actinides than conventional critical reactors, and in this way, increasing the transmutation rates of these elements, that are the main responsible of the long-term radiotoxicity of nuclear waste. One of the key points that have been identified for the operation of an industrial-scale ADS is the need of continuously monitoring the reactivity of the subcritical system during operation. For this reason, since the 1990s a number of experiments have been conducted in zero-power subcritical assemblies (MUSE, RACE, KUCA, Yalina, GUINEVERE/FREYA) in order to experimentally validate these techniques. In this context, the present thesis is concerned with the validation of reactivity monitoring techniques at the Yalina-Booster subcritical assembly. This assembly belongs to the Joint Institute for Power and Nuclear Research (JIPNR-Sosny) of the National Academy of Sciences of Belarus. Experiments concerning reactivity monitoring have been performed in this facility under the EUROTRANS project of the 6th EU Framework Program in year 2008 under the direction of CIEMAT. Two types of experiments have been carried out: experiments with a pulsed neutron source (PNS) and experiments with a continuous source with short interruptions (beam trips). For the case of the first ones, PNS experiments, two fundamental techniques exist to measure the reactivity, known as the prompt

  11. Chirality controlled responsive self-assembled nanotubes in water

    NARCIS (Netherlands)

    van Dijken, D. J.; Stacko, P.; Stuart, M. C. A.; Browne, W. R.; Feringa, B. L.

    2017-01-01

    The concept of using chirality to dictate dimensions and to store chiral information in self-assembled nanotubes in a fully controlled manner is presented. We report a photoresponsive amphiphile that co-assembles with its chiral counterpart to form nanotubes and demonstrate how chirality can be used

  12. Analysis of reactivity determination methods in the subcritical experiment Yalina

    Science.gov (United States)

    Persson, Carl-Magnus; Seltborg, Per; Åhlander, Alexandra; Gudowski, Waclaw; Stummer, Thomas; Kiyavitskaya, Hanna; Bournos, Victor; Fokov, Yurij; Serafimovich, Ivan; Chigrinov, Sergey

    2005-12-01

    Different reactivity determination methods have been investigated, based on experiments performed at the subcritical assembly Yalina in Minsk, Belarus. The development of techniques for on-line monitoring of the reactivity level in a future accelerator-driven system (ADS) is of major importance for safe operation. Since an ADS is operating in a subcritical mode, the safety margin to criticality must be sufficiently large. The investigated methods are the Slope Fit Method, the Sjöstrand Method and the Source Jerk Method. The results are compared with Monte Carlo simulations performed with different nuclear data libraries. The results of the Slope Fit Method are in good agreement with the Monte Carlo simulation results, whereas the Sjöstrand Method appears to underestimate the criticality somewhat. The Source Jerk Method is subject to inadequate statistical accuracy.

  13. Methodological studies on the VVER-440 control assembly calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hordosy, G.; Kereszturi, A.; Maraczy, C. [KFKI Atomic Energy Research Institute, Budapest (Hungary)

    1995-12-31

    The control assembly regions of VVER-440 reactors are represented by 2-group albedo matrices in the global calculations of the KARATE code system. Some methodological aspects of calculating albedo matrices with the COLA transport code are presented. Illustrations are given how these matrices depend on the relevant parameters describing the boron steel and steel regions of the control assemblies. The calculation of the response matrix for a node consisting of two parts filled with different materials is discussed.

  14. Development study on subcriticality monitor. 1. Report under business contract with Japan Nuclear Fuel Cycle Development Institute

    CERN Document Server

    Yamada, S

    2002-01-01

    In this trust fund, we reviewed subcriticality measuring methods and neutron or gamma ray measuring and date transmission systems appropriate for realizing inexpensive on-line criticality surveillance systems, which is required for ensuring the safety of nuclear fuel reprocessing plants. Since the neutron flux level in subcritical systems is fairly low without external neutron sources, it is desirable to use pulse type neutron detectors for subcritical measurement systems. This logically implies that subcriticality measurement methods based on the temporal domain should be used for developing an on-line criticality surveillance system. In the deep subcriticality conditions, a strong external neutron source is needed for eactivity measurement and a D-T tube can be used in order to improve the accuracy of the measurement. A D-T tube is convenient since it is free from Tritium problem since Tritium is sealed in an airtight container and also can be controlled by power supply. Hence, under deep subcritical condit...

  15. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Amar, E-mail: image@barc.gov.in; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P.S.; Bishnoi, Saroj

    2015-05-01

    Highlights: •Experimental subcritical facility BRAHMMA coupled to D-D/D-T neutron generator. •Preliminary results of PNS experiments reported. •Feynman-alpha noise measurements explored with continuous source. -- Abstract: The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated k{sub eff} of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k{sub s} and external neutron source efficiency φ{sup ∗} in great details. Experiments with D-T neutrons are also underway.

  16. Research on assembly reliability control technology for computer numerical control machine tools

    Directory of Open Access Journals (Sweden)

    Yan Ran

    2017-01-01

    Full Text Available Nowadays, although more and more companies focus on improving the quality of computer numerical control machine tools, its reliability control still remains as an unsolved problem. Since assembly reliability control is very important in product reliability assurance in China, a new key assembly processes extraction method based on the integration of quality function deployment; failure mode, effects, and criticality analysis; and fuzzy theory for computer numerical control machine tools is proposed. Firstly, assembly faults and assembly reliability control flow of computer numerical control machine tools are studied. Secondly, quality function deployment; failure mode, effects, and criticality analysis; and fuzzy theory are integrated to build a scientific extraction model, by which the key assembly processes meeting both customer functional demands and failure data distribution can be extracted, also an example is given to illustrate the correctness and effectiveness of the method. Finally, the assembly reliability monitoring system is established based on key assembly processes to realize and simplify this method.

  17. Enzyme-assisted self-assembly under thermodynamic control.

    Science.gov (United States)

    Williams, Richard J; Smith, Andrew M; Collins, Richard; Hodson, Nigel; Das, Apurba K; Ulijn, Rein V

    2009-01-01

    The production of functional molecular architectures through self-assembly is commonplace in biology, but despite advances, it is still a major challenge to achieve similar complexity in the laboratory. Self-assembled structures that are reproducible and virtually defect free are of interest for applications in three-dimensional cell culture, templating, biosensing and supramolecular electronics. Here, we report the use of reversible enzyme-catalysed reactions to drive self-assembly. In this approach, the self-assembly of aromatic short peptide derivatives provides a driving force that enables a protease enzyme to produce building blocks in a reversible and spatially confined manner. We demonstrate that this system combines three features: (i) self-correction--fully reversible self-assembly under thermodynamic control; (ii) component-selection--the ability to amplify the most stable molecular self-assembly structures in dynamic combinatorial libraries; and (iii) spatiotemporal confinement of nucleation and structure growth. Enzyme-assisted self-assembly therefore provides control in bottom-up fabrication of nanomaterials that could ultimately lead to functional nanostructures with enhanced complexities and fewer defects.

  18. Control of nanoparticle self-assemblies using distorted liquid crystals

    Science.gov (United States)

    Lacaze, Emmanuelle; Coursault, Delphine

    This chapter concerns the structure and the optical properties of nanoparticle (NP)/liquid crystal (LC) composites in the presence of LC distortion. After a first description of the general behaviour of NPs at the proximity of distorted LC areas, the first section of the chapter discusses the stabilization of the LC phases, characterized by the presence of topological defects in presence of NPs. The assemblies of NPs induced by distorted LC films is addressed in the second section. The last section then extensively develops the structure and optical properties of NP assemblies created within topological defects. Specific localisation and orientations of the NPs will be discussed, but also possible control of the size and shape of the NP assemblies, together with control of the distances between NPs in the assemblies, leading to original optical properties of the composites as far as uorescent or gold NPs are concerned.

  19. Optimal control of electrostatic self-assembly of binary monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Shestopalov, N V; Henkelman, G; Powell, C T; Rodin, G J [Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: nikolay@ices.utexas.edu

    2009-05-15

    A simple macroscopic model is used to determine an optimal annealing schedule for self-assembly of binary monolayers of spherical particles. The model assumes that a single rate-controlling mechanism is responsible for the formation of spatially ordered structures and that its rate follows an Arrhenius form. The optimal schedule is derived in an analytical form using classical optimization methods. Molecular dynamics simulations of the self-assembly demonstrate that the proposed schedule outperforms other schedules commonly used for simulated annealing.

  20. Monte Carlo Alpha Iteration Algorithm for a Subcritical System Analysis

    Directory of Open Access Journals (Sweden)

    Hyung Jin Shim

    2015-01-01

    Full Text Available The α-k iteration method which searches the fundamental mode alpha-eigenvalue via iterative updates of the fission source distribution has been successfully used for the Monte Carlo (MC alpha-static calculations of supercritical systems. However, the α-k iteration method for the deep subcritical system analysis suffers from a gigantic number of neutron generations or a huge neutron weight, which leads to an abnormal termination of the MC calculations. In order to stably estimate the prompt neutron decay constant (α of prompt subcritical systems regardless of subcriticality, we propose a new MC alpha-static calculation method named as the α iteration algorithm. The new method is derived by directly applying the power method for the α-mode eigenvalue equation and its calculation stability is achieved by controlling the number of time source neutrons which are generated in proportion to α divided by neutron speed in MC neutron transport simulations. The effectiveness of the α iteration algorithm is demonstrated for two-group homogeneous problems with varying the subcriticality by comparisons with analytic solutions. The applicability of the proposed method is evaluated for an experimental benchmark of the thorium-loaded accelerator-driven system.

  1. Effective Light Directed Assembly of Building Blocks with Microscale Control.

    Science.gov (United States)

    Dinh, Ngoc-Duy; Luo, Rongcong; Christine, Maria Tankeh Asuncion; Lin, Weikang Nicholas; Shih, Wei-Chuan; Goh, James Cho-Hong; Chen, Chia-Hung

    2017-06-01

    Light-directed forces have been widely used to pattern micro/nanoscale objects with precise control, forming functional assemblies. However, a substantial laser intensity is required to generate sufficient optical gradient forces to move a small object in a certain direction, causing limited throughput for applications. A high-throughput light-directed assembly is demonstrated as a printing technology by introducing gold nanorods to induce thermal convection flows that move microparticles (diameter = 40 µm to several hundreds of micrometers) to specific light-guided locations, forming desired patterns. With the advantage of effective light-directed assembly, the microfluidic-fabricated monodispersed biocompatible microparticles are used as building blocks to construct a structured assembly (≈10 cm scale) in ≈2 min. The control with microscale precision is approached by changing the size of the laser light spot. After crosslinking assembly of building blocks, a novel soft material with wanted pattern is approached. To demonstrate its application, the mesenchymal stem-cell-seeded hydrogel microparticles are prepared as functional building blocks to construct scaffold-free tissues with desired structures. This light-directed fabrication method can be applied to integrate different building units, enabling the bottom-up formation of materials with precise control over their internal structure for bioprinting, tissue engineering, and advanced manufacturing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A force-feedback control system for micro-assembly

    Science.gov (United States)

    Lu, Zhe; Chen, Peter C. Y.; Ganapathy, Anand; Zhao, Guoyong; Nam, Joohoo; Yang, Guilin; Burdet, Etienne; Teo, Cheeleong; Meng, Qingnian; Lin, Wei

    2006-09-01

    In this paper, we report the development of an explicit force-feedback control system for micro-assembly, focusing on the key issues of force transmission and control. The force-feedback system is incorporated with a compound flexure stage, which is driven by a voice-coil actuator and designed to provide frictionless translation motion along one axis. A force sensor measures the interaction force between the micromanipulator and its environment, while an explicit force controller controls the interaction force to follow a desired force trajectory. The effectiveness of this prototype force-control system has been demonstrated in an experimental application, where parts (with dimensions in microns) were picked up and assembled under explicit force-feedback control.

  3. Controlled self assembly of collagen nanoparticle

    Science.gov (United States)

    Papi, Massimiliano; Palmieri, Valentina; Maulucci, Giuseppe; Arcovito, Giuseppe; Greco, Emanuela; Quintiliani, Gianluca; Fraziano, Maurizio; De Spirito, Marco

    2011-11-01

    In recent years carrier-mediated drug delivery has emerged as a powerful methodology for the treatment of various pathologies. The therapeutic index of traditional and novel drugs is enhanced via the increase of specificity due to targeting of drugs to a particular tissue, cell or intracellular compartment, the control over release kinetics, the protection of the active agent, or a combination of the above. Collagen is an important biomaterial in medical applications and ideal as protein-based drug delivery platform due to its special characteristics, such as biocompatibility, low toxicity, biodegradability, and weak antigenicity. While some many attempts have been made, further work is needed to produce fully biocompatible collagen hydrogels of desired size and able to release drugs on a specific target. In this article we propose a novel method to obtain spherical particles made of polymerized collagen surrounded by DMPC liposomes. The liposomes allow to control both the particles dimension and the gelling environment during the collagen polymerization. Furthermore, an optical based method to visualize and quantify each step of the proposed protocol is detailed and discussed.

  4. Integrated Quality Control of Precision Assemblies using Computed Tomography

    DEFF Research Database (Denmark)

    Stolfi, Alessandro

    coor-dinate measuring machines (CMMs) when working with complex and fragile parts. This Ph.D. project at DTU Mechanical Engineering concerns the applicability of CT for quality control of precision assem-blies. Investigations to quantify the accuracy of CT measurements, reference artefacts to correct...

  5. Numerical simulations of subcritical reactor kinetics in thermal hydraulic transient phases

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, J.; Park, W. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A subcritical reactor driven by a linear proton accelerator has been considered as a nuclear waste incinerator at Korea Atomic Energy Research Institute (KAERI). Since the multiplication factor of a subcritical reactor is less than unity, to compensate exponentially decreasing fission neutrons, external neutrons form spallation reactions are essentially required for operating the reactor in its steady state. Furthermore, the profile of accelerator beam currents is very important in controlling a subcritical reactor, because the reactor power varies in accordance to the profile of external neutrons. We have developed a code system to find numerical solutions of reactor kinetics equations, which are the simplest dynamic model for controlling reactors. In a due course of our previous numerical study of point kinetics equations for critical reactors, however, we learned that the same code system can be used in studying dynamic behavior of the subcritical reactor. Our major motivation of this paper is to investigate responses of subcritical reactors for small changes in thermal hydraulic parameters. Building a thermal hydraulic model for the subcritical reactor dynamics, we performed numerical simulations for dynamic responses of the reactor based on point kinetics equations with a source term. Linearizing a set of coupled differential equations for reactor responses, we focus our research interest on dynamic responses of the reactor to variations of the thermal hydraulic parameters in transient phases. 5 refs., 8 figs. (Author)

  6. Subcritical flutter in the acoustics of friction

    National Research Council Canada - National Science Library

    O.N Kirillov

    2008-01-01

    ...-simple eigenfrequencies at the nodes. At contact with friction pads, the rotating continua, such as the singing wine glass or the squealing disc brake, start to vibrate owing to the subcritical flutter instability...

  7. Multi-sensor control for precise assembly of optical components

    Directory of Open Access Journals (Sweden)

    Ma Li

    2014-06-01

    Full Text Available In order to perform an optical assembly accurately, a multi-sensor control strategy is developed which includes an attitude measurement system, a vision system, a loss measurement system and a force sensor. A 3-DOF attitude measuring method using linear variable differential transformers (LVDT is designed to adjust the relation of position and attitude between the spherical mirror and the resonator. A micro vision feedback system is set up to extract the light beam and the diaphragm, which can achieve the coarse positioning of the spherical mirror in the optical assembly process. A rapid self-correlation method is presented to analyze the spectrum signal for the fine positioning. In order to prevent the damage of the optical components and realize sealing of the resonator, a hybrid force-position control is constructed to control the contact force of the optical components. The experimental results show that the proposed multi-sensor control strategy succeeds in accomplishing the precise assembly of the optical components, which consists of parallel adjustment, macro coarse adjustment, macro approach, micro fine adjustment, micro approach and optical contact. Therefore, the results validate the multi-sensor control strategy.

  8. Microcontrollers for Mechanical Engineers: From Assembly Language to Controller Implementation

    OpenAIRE

    Salzman, Noah; Meckl, Peter H.

    2013-01-01

    This paper describes the evolution of a graduate and advanced undergraduate mechanical engineering course on microcontrollers and electromechanical control systems. The course begins with developing an understanding of the architecture of the microcontroller, and low-level programming in assembly language. It then proceeds to working with various functions of the microcontroller, including serial communications, interrupts, analog to digital conversion, and digital to analog conversion. Final...

  9. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    Keywords. Accelerator driven systems; nuclear waste transmutation; computer codes; reactor physics; reactor noise; kinetics; burnup; transport theory; Monte Carlo; thorium utilization; neutron multiplication; sub-criticality; sub-critical facilities.

  10. Controlled short-linkage assembly of functional nano-objects

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhary, Shilpi; Kamra, Tripta [Division of Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden); ENI AB, Malmö (Sweden); Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Uddin, Khan Mohammad Ahsan [Division of Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden); Snezhkova, Olesia [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Jayawardena, H. Surangi N. [Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., Lowell, MA 01854 (United States); Yan, Mingdi [Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., Lowell, MA 01854 (United States); Department of Chemistry, KTH – Royal Institute of Technology, Teknikringen 30, S-10044 Stockholm (Sweden); Montelius, Lars [ENI AB, Malmö (Sweden); Schnadt, Joachim, E-mail: joachim.schnadt@sljus.lu.se [Division of Synchrotron Radiation Research, Lund University, Box 118, 221 00 Lund (Sweden); Ye, Lei, E-mail: lei.ye@tbiokem.lth.se [Division of Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden)

    2014-05-01

    Graphical abstract: - Highlights: • Fast photoconjugation of nanoparticles on surface. • Non-destructive feature guarantees intact function of nanoparticles. • Direct contact between nano-objects allows efficient photon and electron transfer. • Possibility of generating patterned nanoparticle assemblies on surface. • Open new opportunities for assembling chemical sensors. - Abstract: In this work, we report a method that allows the deterministic, photo-controlled covalent assembly of nanoparticles directly on surface. As a model system, we study the conjugation of molecularly imprinted polymer (MIP) nanoparticles on a glass surface and confirm that the immobilized nanoparticles maintain their molecular recognition functionality. The glass slide was first modified with perfluorophenylazide and then used to bind MIP nanoparticles under UV irradiation. After each step the surface was analyzed by water contact angle measurement, fluorescence microscopy, scanning electron microscopy, and/or synchrotron-based X-ray photoelectron spectroscopy. The MIP nanoparticles immobilized on the glass surface remained stable and maintained specific binding for the template molecule, propranolol. The method developed in this work allows MIP nanoparticles to be directly coupled to a flat surface, offering a straightforward means to construct robust chemical sensors. Using the reported photo conjugation method, it is possible to generate patterned assembly of nanoparticles using a photomask. Since perfluorophenylazide-based photochemistry works with all kinds of organic material, the method developed in this work is expected to enable immobilization of not only MIPs but also other kinds of organic and inorganic–organic core–shell particles for various applications involving photon or electron transfer.

  11. Chalcogenide nanocrystal assembly: Controlling heterogeneity and modulating heterointerfaces

    Science.gov (United States)

    Davis, Jessica

    chalcogenide NC gels with different NC components with control over the degree of mixing. In order to control the degree of mixing, the factors that underscore sol-gel oxidative assembly were elucidated and the aggregation and gelation kinetics of metal chalcogenide QDs were monitored through time-resolved dynamic light scattering (TR-DLS), and nuclear magnetic resonance spectroscopy (NMR). Through these kinetic studies of the surface speciation of metal chalcogenides, control over heterogeneity in dual component CdSe-ZnS system, was achieved through adjustment of the capping ligand, the native crystal structure and the chalcogenide, thereby changing the relative rates of assembly for each component independently.

  12. Control assembly for controlling a fuel cell system during shutdown and restart

    Science.gov (United States)

    Venkataraman, Ramki; Berntsen, George; Carlson, Glenn L.; Farooque, Mohammad; Beachy, Dan; Peterhans, Stefan; Bischoff, Manfred

    2010-06-15

    A fuel cell system and method in which the fuel cell system receives and an input oxidant gas and an input fuel gas, and in which a fuel processing assembly is provided and is adapted to at least humidify the input fuel gas which is to be supplied to the anode of the fuel cell of the system whose cathode receives the oxidant input gas via an anode oxidizing assembly which is adapted to couple the output of the anode of the fuel cell to the inlet of the cathode of the fuel cell during normal operation, shutdown and restart of the fuel cell system, and in which a control assembly is further provided and is adapted to respond to shutdown of the fuel cell system during which input fuel gas and input oxidant gas cease to be received by the fuel cell system, the control assembly being further adapted to, when the fuel cell system is shut down: control the fuel cell system so as to enable a purging gas to be able to flow through the fuel processing assembly to remove humidified fuel gas from the processing assembly and to enable a purging gas to be able to flow through the anode of the fuel cell.

  13. LAVENDER: A steady-state core analysis code for design studies of accelerator driven subcritical reactors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengcheng; Wu, Hongchun; Cao, Liangzhi; Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn; Huang, Kai; He, Mingtao; Li, Xunzhao

    2014-10-15

    Highlights: • A new code system for design studies of accelerator driven subcritical reactors (ADSRs) is developed. • S{sub N} transport solver in triangular-z meshes, fine deletion analysis and multi-channel thermal-hydraulics analysis are coupled in the code. • Numerical results indicate that the code is reliable and efficient for design studies of ADSRs. - Abstract: Accelerator driven subcritical reactors (ADSRs) have been proposed and widely investigated for the transmutation of transuranics (TRUs). ADSRs have several special characteristics, such as the subcritical core driven by spallation neutrons, anisotropic neutron flux distribution and complex geometry etc. These bring up requirements for development or extension of analysis codes to perform design studies. A code system named LAVENDER has been developed in this paper. It couples the modules for spallation target simulation and subcritical core analysis. The neutron transport-depletion calculation scheme is used based on the homogenized cross section from assembly calculations. A three-dimensional S{sub N} nodal transport code based on triangular-z meshes is employed and a multi-channel thermal-hydraulics analysis model is integrated. In the depletion calculation, the evolution of isotopic composition in the core is evaluated using the transmutation trajectory analysis algorithm (TTA) and fine depletion chains. The new code is verified by several benchmarks and code-to-code comparisons. Numerical results indicate that LAVENDER is reliable and efficient to be applied for the steady-state analysis and reactor core design of ADSRs.

  14. Control Large Nanoparticle Assemblies in Suparmolecular Nanoparticle Thin Films

    Science.gov (United States)

    Huang, Jingyu; Xu, Ting

    2015-03-01

    Nanocomposites can generate new properties beyond those offered by organic and inorganic building blocks to meet the demands in functional materials. The collective properties of nanocomposite materials depend on both the nature of individual building block and their spatial arrangements. With the recent development, colloidal synthesis and surface modification methods provide inorganic nanoparticles (NPs) with various sizes, shapes, compositions and properties in a facile manner. Block copolymer-based supramolecules further provide more versatile routes to control spatial arrangement of the nanoparticles over multiple length scales. Nanoparticle size is a critical parameter determining the optical and electronic properties. However, most of studies to date focused on nanoparticle smaller than 10 nm in size. Here, our recent studies showed that the assembly of nanoparticles with size larger than 10 nm can be achieved in the supramolecular nanocomposite thin films by finely tuning the ligand-polymer interactions and the sample treatment conditions. Both the overall morphology of the nanoparticle assemblies and inter-particle distances can be readily tailored. These new results opened a viable approach to construct functional materials using nanoparticles with different quantum confinement effects.

  15. Force-controlled robotic assembly processes of rigid and flexible objects methodologies and applications

    CERN Document Server

    Ghalyan, Ibrahim Fahad Jasim

    2016-01-01

    This book provides comprehensive and integrated approaches for rigid and flexible object assembly. It presents comparison studies with the available force-guided robotic processes and covers contact-state modeling, scheme control strategies, and position searching algorithms. Further, it includes experimental validations for different assembly situations, including those for the assembly of industrial parts taken from the automotive industry. .

  16. Accurate length control of supramolecular oligomerization: Vernier assemblies.

    Science.gov (United States)

    Hunter, Christopher A; Tomas, Salvador

    2006-07-12

    Linear oligomeric supramolecular assemblies of defined length have been generated using the Vernier principle. Two molecules, containing a different number (n and m) of mutually complementary binding sites, separated by the same distance, interact with each other to form an assembly of length (n x m). The assembly grows in the same way as simple supramolecular polymers, but at a molecular stop signal, when the binding sites come into register, the assembly terminates giving an oligomer of defined length. This strategy has been realized using tin and zinc porphyrin oligomers as the molecular building blocks. In the presence of isonicotinic acid, a zinc porphyrin trimer and a tin porphyrin dimer form a 3:4 triple stranded Vernier assembly six porphyrins long. The triple strand Vernier architecture introduced here adds an additional level of cooperativity, yielding a stability and selectivity that cannot be achieved via a simple Vernier approach. The assembly properties of the system were characterized using fluorescence titrations and size-exclusion chromatography (SEC). Assembly of the Vernier complex is efficient at micromolar concentrations in nonpolar solvents, and under more competitive conditions, a variety of fragmentation assemblies can be detected, allowing determination of the stability constants for this system and detailed speciation profiles to be constructed.

  17. Tuning colloidal interactions in subcritical solvents by solvophobicity: explicit versus implicit modeling.

    Science.gov (United States)

    Dzubiella, J; Chakrabarti, J; Löwen, H

    2009-07-28

    The distance-resolved effective interaction between two colloidal particles in a subcritical solvent is explored both by an explicit and implicit modeling. An implicit solvent approach based on a simple thermodynamic interface model is tested against grand-canonical Monte Carlo computer simulations using explicit Lennard-Jones solvent molecules. Close to liquid-gas coexistence, a joint gas bubble surrounding the colloidal particle pair yields an effective attraction between the colloidal particles, the strength of which can be vastly tuned by the solvophobicity of the colloids. The implicit model is in good agreement with our explicit computer simulations, thus enabling an efficient modeling and evaluation of colloidal interactions and self-assembly in subcritical solvent environments.

  18. Assembly of bio-nanoparticles for double controlled drug release.

    Directory of Open Access Journals (Sweden)

    Wei Huang

    Full Text Available A critical limiting factor of chemotherapy is the unacceptably high toxicity. The use of nanoparticle based drug carriers has significantly reduced the side effects and facilitated the delivery of drugs. Source of the remaining side effect includes (1 the broad final in vivo distribution of the administrated nanoparticles, and (2 strong basal drug release from nanoparticles before they could reach the tumor. Despite the advances in pH-triggered release, undesirable basal drug release has been a constant challenge under in vivo conditions. In this study, functionalized single walled carbon nanohorn supported immunoliposomes were assembled for paclitaxel delivery. The immunoliposomes were formulated with polyethylene glycol, thermal stable and pH sensitive phospholipids. Each nanohorn was found to be encapsulated within one immunoliposome. Results showed a highly pH dependent release of paclitaxel in the presence of serum at body temperature with minimal basal release under physiological conditions. Upon acidification, paclitaxel was released at a steady rate over 30 days with a cumulative release of 90% of the loaded drug. The drug release results proved our hypothesized double controlled release mechanism from the nanoparticles. Other results showed the nanoparticles have doubled loading capacity compared to that of traditional liposomes and higher affinity to breast cancer cells overexpressing Her2 receptors. Internalized nanoparticles were found in lysosomes.

  19. Stoichiometric control of DNA-grafted colloid self-assembly

    Science.gov (United States)

    Vo, Thi; Kumar, Sanat; Srinivasan, Babji; Pal, Suchetan; Zhang, Yugang; Gang, Oleg

    2015-01-01

    There has been considerable interest in understanding the self-assembly of DNA-grafted nanoparticles into different crystal structures, e.g., CsCl, AlB2, and Cr3Si. Although there are important exceptions, a generally accepted view is that the right stoichiometry of the two building block colloids needs to be mixed to form the desired crystal structure. To incisively probe this issue, we combine experiments and theory on a series of DNA-grafted nanoparticles at varying stoichiometries, including noninteger values. We show that stoichiometry can couple with the geometries of the building blocks to tune the resulting equilibrium crystal morphology. As a concrete example, a stoichiometric ratio of 3:1 typically results in the Cr3Si structure. However, AlB2 can form when appropriate building blocks are used so that the AlB2 standard-state free energy is low enough to overcome the entropic preference for Cr3Si. These situations can also lead to an undesirable phase coexistence between crystal polymorphs. Thus, whereas stoichiometry can be a powerful handle for direct control of lattice formation, care must be taken in its design and selection to avoid polymorph coexistence. PMID:25848044

  20. Control of extracellular matrix assembly by syndecan-2 proteoglycan

    DEFF Research Database (Denmark)

    Klass, C M; Couchman, J R; Woods, A

    2000-01-01

    Extracellular matrix (ECM) deposition and organization is maintained by transmembrane signaling and integrins play major roles. We now show that a second transmembrane component, syndecan-2 heparan sulfate proteoglycan, is pivotal in matrix assembly. Chinese Hamster Ovary (CHO) cells were stably...... transfected with full length (S2) or truncated syndecan-2 lacking the C-terminal 14 amino acids of the cytoplasmic domain (S2deltaS). No differences in the amount of matrix assembly were noted with S2 cells, but those expressing S2deltaS could not assemble laminin or fibronectin into a fibrillar matrix....... The loss of matrix formation was not caused by a failure to synthesize or externalize ECM components as determined by metabolic labeling or due to differences in surface expression of alpha5 or beta1 integrin. The matrix assembly defect was at the cell surface, since S2deltaS cells also lost the ability...

  1. Subcritical water extraction of lipids from wet algal biomass

    Science.gov (United States)

    Deng, Shuguang; Reddy, Harvind K.; Schaub, Tanner; Holguin, Francisco Omar

    2016-05-03

    Methods of lipid extraction from biomass, in particular wet algae, through conventionally heated subcritical water, and microwave-assisted subcritical water. In one embodiment, fatty acid methyl esters from solids in a polar phase are further extracted to increase biofuel production.

  2. Production of value added materials by subcritical water hydrolysis ...

    African Journals Online (AJOL)

    The aim of this study was the determination of the best experimental conditions for the production of useful materials such as amino acids by subcritical water hydrolysis from supercritical carbon dioxide extracted krill residues and to compare the results with raw krill. Subcritical water hydrolysis efficiency from raw and ...

  3. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    utilization; neutron multiplication; sub-criticality; sub-critical facilities. PACS Nos 89.30.Gg; 28.41.-I; 28.50.-k. 1. Introduction. Accelerator driven systems (ADS) are attracting worldwide attention increasingly due to their superior safety characteristics and their potential for burning actinide and fission product-waste and energy ...

  4. Subcritical water extraction of bioactive compounds from dry loquat ...

    African Journals Online (AJOL)

    ERASTO

    concentrated in a rotary evaporator at 60°C until dry. The total extraction yield was obtained by the mean value of the total extracts divided by the mass of dry loquat leaves used. Subcritical water extraction. Subcritical water extraction was carried using an extractor. (Hangzhou Huali Co. Ltd, Hangzhou, China). The extractor ...

  5. Assembly of Liposomes Controlled by Triple Helix Formation

    DEFF Research Database (Denmark)

    Vogel, Stefan; Jakobsen, Ulla

    2013-01-01

    sequences (G or C-rich) to explore the applicability of the method for different triple helical assembly modes. We demonstrate advantages and limitations of the approach and proof the reversible and reproducible formation of liposome aggregates during thermal denaturation cycles. Nanoparticle tracking...

  6. Lipophilic DNA-conjugates: DNA controlled assembly of liposomes

    DEFF Research Database (Denmark)

    Vogel, Stefan; Jakobsen, Ulla

    2009-01-01

    DNA detection systems based on encoded solid particles have been reported but require often tedious and not generally applicable surface chemistry. In the present study a system comprised of a lipid-modified DNA probe sequence and unmodified DNA target sequences is used to non-covalently assemble...

  7. Supramolecular control of self-assembling terthiophene-peptide conjugates through the amino acid side chain

    Energy Technology Data Exchange (ETDEWEB)

    Lehrman, Jessica A.; Cui, Honggang; Tsai, Wei-Wen; Moyer, Tyson J.; Stupp, Samuel I. [NWU

    2013-07-30

    The self-assembly of oligothiophene–peptide conjugates can be directed through the systematic variation of the peptide sequence into different nanostructures, including flat spicules, nanotubes, spiral sheets, and giant, flat sheets. Furthermore, the assembly of these molecules is not controlled by steric interactions between the amino acid side chains.

  8. Rigid Biopolymer Nanocrystal Systems for Controlling Multicomponent Nanoparticle Assembly and Orientation in Thin Film Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer [Univ. of Colorado, Boulder, CO (United States)

    2016-10-31

    We have discovered techniques to synthesize well-defined DN conjugated nanostructures that are stable in a wide variety of conditions needed for DNA mediated assembly. Starting from this, we have shown that DNA can be used to control the assembly and integration of semiconductor nanocrystals into thin film devices that show photovoltaic effects.

  9. Electrochemically controlled self-assembled monolayers characterized with molecular and sub-molecular resolution

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Welinder, Anna Christina; Chi, Qijin

    2011-01-01

    in the investigations of electronic structures and assembling dynamics of electrochemically controlled self-assembled monolayers (SAMs) of thiol containing molecules on gold surfaces. A brief introduction is first given and particularly illustrated by a Table summarizing the molecules studied, the surface lattice...

  10. Guest Controlled Nonmonotonic Deep Cavity Cavitand Assembly State Switching.

    Science.gov (United States)

    Tang, Du; Barnett, J Wesley; Gibb, Bruce C; Ashbaugh, Henry S

    2017-11-30

    Octa-acid (OA) and tetra-endo-methyl octa-acid (TEMOA) are water-soluble, deep-cavity cavitands with nanometer-sized nonpolar pockets that readily bind complementary guests, such as n-alkanes. Experimentally, OA exhibits a progression of 1:1 to 2:2 to 2:1 host/guest complexes (X:Y where X is the number of hosts and Y is the number of guests) with increasing alkane chain length from methane to tetradecane. Differing from OA only by the addition of four methyl groups ringing the portal of the pocket, TEMOA exhibits a nonmonotonic progression of assembly states from 1:1 to 2:2 to 1:1 to 2:1 with increasing guest length. Here we present a systematic molecular simulation study to parse the molecular and thermodynamic determinants that distinguish the succession of assembly stoichiometries observed for these similar hosts. Potentials of mean force between hosts and guests, determined via umbrella sampling, are used to characterize association free energies. These free energies are subsequently used in a reaction network model to predict the equilibrium distributions of assemblies. Our models accurately reproduce the experimentally observed trends, showing that TEMOA's endo-methyl units constrict the opening of the binding pocket, limiting the conformations available to bound guests and disrupting the balance between monomeric complexes and dimeric capsules. The success of our simulations demonstrate their utility at interpreting the impact of even simple chemical modifications on supramolecular assembly and highlight their potential to aid bottom-up design.

  11. Dynamic properties of nucleated microtubules: GTP utilisation in the subcritical concentration regime.

    Science.gov (United States)

    Symmons, M F; Martin, S R; Bayley, P M

    1996-11-01

    Microtubule assembly kinetics have been studied quantitatively under solution conditions supporting microtubule dynamic instability. Purified GTP-tubulin (Tu-GTP) and covalently cross-linked short microtubule seeds (EGS-seeds; Koshland et al. (1988) Nature 331, 499) were used with and without biotinylation. Under sub-critical concentration conditions ([Tu-GTP] assembly, that was found to abolish the GDP release. The variation of the GDP release with tubulin concentration (Jh(c) plot) was determined below the critical concentration (Cc). The GDP production observed was consistent with the elongation of the observed seeded microtubules with an apparent rate constant of 1.5 x 10(6) M-1 second-1 above a threshold of approximately 1 microM tubulin. The form of this Jh(c) plot for elongation below Cc is reproduced by the Lateral Cap model for microtubule dynamic instability adapted for seeded assembly. The behaviour of the system is contrasted with that previously studied in the absence of detectable microtubule elongation (Caplow and Shanks (1990) J. Biol. Chem. 265, 8935-8941). The approach provides a means of monitoring microtubule dynamics at concentrations inaccessible to optical microscopy, and shows that essentially the same dynamic mechanisms apply at all concentrations. Numerical simulation of the subcritical concentration regime shows dynamic growth features applicable to the initiation of microtubule growth in vivo.

  12. KAT: a K-mer analysis toolkit to quality control NGS datasets and genome assemblies.

    Science.gov (United States)

    Mapleson, Daniel; Garcia Accinelli, Gonzalo; Kettleborough, George; Wright, Jonathan; Clavijo, Bernardo J

    2017-02-15

    De novo assembly of whole genome shotgun (WGS) next-generation sequencing (NGS) data benefits from high-quality input with high coverage. However, in practice, determining the quality and quantity of useful reads quickly and in a reference-free manner is not trivial. Gaining a better understanding of the WGS data, and how that data is utilized by assemblers, provides useful insights that can inform the assembly process and result in better assemblies. We present the K-mer Analysis Toolkit (KAT): a multi-purpose software toolkit for reference-free quality control (QC) of WGS reads and de novo genome assemblies, primarily via their k-mer frequencies and GC composition. KAT enables users to assess levels of errors, bias and contamination at various stages of the assembly process. In this paper we highlight KAT's ability to provide valuable insights into assembly composition and quality of genome assemblies through pairwise comparison of k-mers present in both input reads and the assemblies. KAT is available under the GPLv3 license at: https://github.com/TGAC/KAT . bernardo.clavijo@earlham.ac.uk. Supplementary data are available at Bioinformatics online.

  13. Self-assembled nanoparticles of glycol chitosan – Ergocalciferol succinate conjugate, for controlled release

    DEFF Research Database (Denmark)

    Quinones, Javier Perez; Gothelf, Kurt Vesterager; Kjems, Jørgen

    2012-01-01

    Glycol chitosan was linked to vitamin D2 hemisuccinate (ergocalciferol hemisuccinate) for controlled release through water-soluble carbodiimide activation. The resulting conjugate formed self-assembled nanoparticles in aqueous solution with particle size of 279 nm and ergocalciferol hemisuccinate...

  14. Chemical and entropic control on the molecular self-assembly process

    Science.gov (United States)

    Packwood, Daniel M.; Han, Patrick; Hitosugi, Taro

    2017-01-01

    Molecular self-assembly refers to the spontaneous assembly of molecules into larger structures. In order to exploit molecular self-assembly for the bottom-up synthesis of nanomaterials, the effects of chemical control (strength of the directionality in the intermolecular interaction) and entropic control (temperature) on the self-assembly process should be clarified. Here we present a theoretical methodology that unambiguously distinguishes the effects of chemical and entropic control on the self-assembly of molecules adsorbed to metal surfaces. While chemical control simply increases the formation probability of ordered structures, entropic control induces a variety of effects. These effects range from fine structure modulation of ordered structures, through to degrading large, amorphous structures into short, chain-shaped structures. Counterintuitively, the latter effect shows that entropic control can improve molecular ordering. By identifying appropriate levels of chemical and entropic control, our methodology can, therefore, identify strategies for optimizing the yield of desired nanostructures from the molecular self-assembly process. PMID:28195175

  15. Docking System Design and Self-Assembly Control of Distributed Swarm Flying Robots

    Directory of Open Access Journals (Sweden)

    Hongxing Wei

    2012-11-01

    Full Text Available This paper presents a novel docking system design and the distributed self-assembly control strategy for a Distributed Swarm Flying Robot (DSFR. The DSFR is a swarm robot comprising many identical robot modules that are able to move on the ground, dock with each other and fly coordinately once self-assembled into a robotic structure. A generalized adjacency matrix method is proposed to describe the configurations of robotic structures. Based on the docking system and the adjacency matrix, experiments are performed to demonstrate and verify the self-assembly control strategy.

  16. Dynamics of Subcritical Bubbles in First Order Phase Transition

    Science.gov (United States)

    Shiromizu, T.; Morikawa, M.; Yokoyama, J.

    1995-11-01

    We derivate the Langevin and the Fokker-Planck equations for the radius of O(3)-symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect of thermal noise on subcritical bubbles is examined. We find that the fluctuation-dissipation relation holds and that in the high temperature phase the system settles down rapidly to the thermal equilibrium state even if it was in a nonequilibrium state initially. We then estimate the typical size of subcritical bubbles as well as the amplitude of fluctuations on that scale. We also discuss their implication to the electroweak phase transition.

  17. Reconfigurable Chiral Self-Assembly of Peptides through Control of Terminal Charges.

    Science.gov (United States)

    Xie, Yanyan; Wang, Yuefei; Qi, Wei; Huang, Renliang; Su, Rongxin; He, Zhimin

    2017-08-01

    Self-assembly of chiral nanostructures is of considerable interest, since the ability to control the chirality of these structures has direct ramifications in biology and materials science. A new approach to design chiral nanostructures from self-assembly of N-(9-fluorenylmethoxycarbonyl)-protected phenylalanine-tryptophan-lysine tripeptides is reported. The terminal charges can induce helical twisting of the assembled β-sheets, enabling the formation of well-defined chiral nanostructures. The degree and direction of twisting in the β-sheets can be precisely tailored through in situ pH and temperature modulations. This enables the assembly of reconfigurable chiral nanomaterials with easily adjustable size and handedness. These results offer new insight into the mechanism of helical twist formation, which may enable the precise assembly of highly dynamical materials with potential applications in biomedicine, chiroptics, and chiral sensing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Control of Surface-Localized, Enzyme-Assisted Self-Assembly of Peptides through Catalyzed Oligomerization.

    Science.gov (United States)

    Vigier-Carrière, Cécile; Wagner, Déborah; Chaumont, Alain; Durr, Baptiste; Lupattelli, Paolo; Lambour, Christophe; Schmutz, Marc; Hemmerlé, Joseph; Senger, Bernard; Schaaf, Pierre; Boulmedais, Fouzia; Jierry, Loïc

    2017-08-22

    Localized self-assembly allowing both spatial and temporal control over the assembly process is essential in many biological systems. This can be achieved through localized enzyme-assisted self-assembly (LEASA), also called enzyme-instructed self-assembly, where enzymes present on a substrate catalyze a reaction that transforms noninteracting species into self-assembling ones. Very few LEASA systems have been reported so far, and the control of the self-assembly process through the surface properties represents one essential step toward their use, for example, in artificial cell mimicry. Here, we describe a new type of LEASA system based on α-chymotrypsin adsorbed on a surface, which catalyzes the production of (KL)nOEt oligopeptides from a KLOEt (K: lysine; L: leucine; OEt ethyl ester) solution. When a critical concentration of the formed oligopeptides is reached near the surface, they self-assemble into β-sheets resulting in a fibrillar network localized at the interface that can extend over several micrometers. One significant feature of this process is the existence of a lag time before the self-assembly process starts. We investigate, in particular, the effect of the α-chymotrypsin surface density and KLOEt concentration on the self-assembly kinetics. We find that the lag time can be finely tuned through the surface density in α-chymotrypsin and KLOEt concentration. For a given surface enzyme concentration, a critical KLOEt concentration exists below which no self-assembly takes place. This concentration increases when the surface density in enzyme decreases.

  19. SUB-LEU-METAL-THERM-001 SUBCRITICAL MEASUREMENTS OF LOW ENRICHED TUBULAR URANIUM METAL FUEL ELEMENTS BEFORE & AFTER IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    SCHWINKENDORF, K.N.

    2006-05-12

    With the shutdown of the Hanford PUREX (Plutonium-Uranium Extraction Plant) reprocessing plant in the 1970s, adequate storage capacity for spent Hanford N Reactor fuel elements in the K and N Reactor pools became a concern. To maximize space utilization in the pools, accounting for fuel burnup was considered. Calculations indicated that at typical fuel exposures for N Reactor, the spent-fuel critical mass would be twice the critical mass for green fuel. A decision was reached to test the calculational result with a definitive experiment. If the results proved positive, storage capacity could be increased and N Reactor operation could be prolonged. An experiment to be conducted in the N Reactor spent-fuel storage pool was designed and assembled and the services of the Battelle Northwest Laboratories (BNWL) (now Pacific Northwest National Laboratory [PNNL]) critical mass laboratory were procured for the measurements. The experiments were performed in April 1975 in the Hanford N Reactor fuel storage pool. The fuel elements were MKIA fuel assemblies, comprising two concentric tubes of low-enriched metallic uranium. Two separate sets of measurements were performed: one with ''green'' (fresh) fuel and one with spent fuel. Both the green and spent fuel, were measured in the same geometry. The spent-fuel MKIA assemblies had an average burnup of 2865 MWd (megawatt days)/t. A constraint was imposed restricting the measurements to a subcritical limit of k{sub eff} = 0.97. Subcritical count rate data was obtained with pulsed-neutron and approach-to-critical measurements. Ten (10) configurations with green fuel and nine (9) configurations with spent fuel are described and evaluated. Of these, 3 green fuel and 4 spent fuel loading configurations were considered to serve as benchmark models. However, shortcomings in experimental data failed to meet the high standards for a benchmark problem. Nevertheless, the data provided by these subcritical measurements can

  20. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

    2017-02-01

    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  1. Astrobionibbler: In Situ Microfluidic Subcritical Water Extraction of Amino Acids

    Science.gov (United States)

    Noell, A. C.; Fisher, A. M.; Takano, N.; Fors-Francis, K.; Sherrit, S.; Grunthaner, F.

    2016-10-01

    A fluidic-chip based instrument for subcritical water extraction (SCWE) of amino acids and other organics from powder samples has been developed. A variety of soil analog extractions have been performed to better understand SCWE capabilities.

  2. Controlling self-assembly of diphenylalanine peptides at high pH using heterocyclic capping groups

    Science.gov (United States)

    Martin, Adam D.; Wojciechowski, Jonathan P.; Robinson, Andrew B.; Heu, Celine; Garvey, Christopher J.; Ratcliffe, Julian; Waddington, Lynne J.; Gardiner, James; Thordarson, Pall

    2017-03-01

    Using small angle neutron scattering (SANS), it is shown that the existence of pre-assembled structures at high pH for a capped diphenylalanine hydrogel is controlled by the selection of N-terminal heterocyclic capping group, namely indole or carbazole. At high pH, changing from a somewhat hydrophilic indole capping group to a more hydrophobic carbazole capping group results in a shift from a high proportion of monomers to self-assembled fibers or wormlike micelles. The presence of these different self-assembled structures at high pH is confirmed through NMR and circular dichroism spectroscopy, scanning probe microscopy and cryogenic transmission electron microscopy.

  3. Metal Controlled Diastereoselective Self-assembly and Circularly Polarized Luminescence of a Chiral Heptanuclear Europium Wheel

    Science.gov (United States)

    Bozoklu, Gülay; Gateau, Christelle; Imbert, Daniel; Pécaut, Jacques; Robeyns, Koen; Filinchuk, Yaroslav; Memon, Farah; Muller, Gilles

    2012-01-01

    The chiral dissymmetric tetradentate ligand SPhbipox (6’-(4-phenyloxazolin-2-yl)-2,2’-bipyridine-6-carboxylic acid) leads to the diastereoselective assembly of a homochiral Eu(III) triangle and of a highly emissive (QY=27%) heptanuclear wheel which is the largest example of chiral luminescent complex of Eu(III) reported to date. We show that the nuclearity of the assembly is controlled by the solvent and the europium cation. All the compounds show large circularly polarized luminescence with an activity which varies with the nature of the assembly (highest for the homochiral trimer). PMID:22548280

  4. Research on quality evaluation and forecast control in assembly process for complex products

    Science.gov (United States)

    Pang, Jihong; Xue, Xiaobo; Jin, Yini; Li, Yongchao

    2017-05-01

    Assembly quality affects complex product’s performance in high degree because the assembly is the end of manufacture process. In this paper, a comprehensive evaluation and forecast control of various factors affecting assembly failure is presented based on theory of gray system. Firstly, the absolute correlation degree and relative degree of correlation are calculated by using data from assembly process of complex products. Then, the comprehensive correlation degree and rank analysis are obtained with the gray method. Finally, the gray system theory is used in quality analysis and forecast control of a valve manufacturer. The final result indicates that excess amount of leakage is the main factor affecting product quality in accord with the actual situation.

  5. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Black, C.T.; Bosworth, J.K.; Paik, M.Y.; Ruiz, R.; Schwartz, E.L.; Huang, J.Q.; Ko, A.W.; Smilgies, D.-M.; Ober, C.K.

    2008-07-22

    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  6. Control of Self-Assembly of Lithographically Patternable Block Copolymer Films

    Energy Technology Data Exchange (ETDEWEB)

    Bosworth, Joan K.; Paik, Marvin Y.; Ruiz, Ricardo; Schwartz, Evan L.; Huang, Jenny Q.; Ko, Albert W.; Smilgies, Detlef-M.; Black, Charles T.; Ober, Christopher K. (Cornell); (IBM)

    2008-08-06

    Poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

  7. Stoichiometry-Controlled Inversion of Supramolecular Chirality in Nanostructures Co-assembled with Bipyridines.

    Science.gov (United States)

    Wang, Fang; Feng, Chuan-Liang

    2018-02-01

    To control supramolecular chirality of the co-assembled nanostructures, one of the remaining issues is how stoichiometry of the different molecules involved in co-assembly influence chiral transformation. Through co-assembly of achiral 1,4-bis(pyrid-4-yl)benzene and chiral phenylalanine-glycine derivative hydrogelators, stoichiometry is found to be an effective tool for controlling supramolecular chirality inversion processes. This inversion is mainly mediated by a delicate balance between intermolecular hydrogen bonding interactions and π-π stacking of the two components, which may subtly change the stacking of the molecules, in turn, the self-assembled nanostructures. This study exemplifies a simplistic way to invert the handedness of chiral nanostructures and provide fundamental understanding of the inherent principles of supramolecular chirality. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    Directory of Open Access Journals (Sweden)

    Fang Duan

    2013-01-01

    Full Text Available The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  9. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    OpenAIRE

    Fang Duan; Yu-fen Chen; Zhong-zheng Sun; Ming-qing Chen; Hui Zhang; Jing Zhang

    2013-01-01

    The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  10. Tower Shielding Reactor II design and operation report. Vol. 3. Assembling and testing of the control mechanism assembly

    Energy Technology Data Exchange (ETDEWEB)

    Ward, D.R.; Holland, L.B.

    1979-09-01

    The mechanisms that are operated to control the reactivity of the Tower Shielding Reactor II(TSR-II) are mounted on a Control Mechanism Housing (CMH) that is centered inside the reactor core. The information required to procure, fabricate, inspect, and assemble a CMH is contained in the ORNL engineering drawings listed in the appropriate sections. The components are fabricated and inspected from these drawings in accordance with a Quality Assurance Plan and a Manufacturing Plan. The material in this report describes the acceptance and performance tests of CMH subassemblies used ty the Tower Shielding Facility (TSF) staff but it can also be used by personnel fabricating the components. This information which was developed and used before the advent of the formalized QA Program and Manufacturing Plans evolved during the fabrication and testing of the first five CMHs.

  11. Towards Robust Predictive Fault–Tolerant Control for a Battery Assembly System

    Directory of Open Access Journals (Sweden)

    Seybold Lothar

    2015-12-01

    Full Text Available The paper deals with the modeling and fault-tolerant control of a real battery assembly system which is under implementation at the RAFI GmbH company (one of the leading electronic manufacturing service providers in Germany. To model and control the battery assembly system, a unified max-plus algebra and model predictive control framework is introduced. Subsequently, the control strategy is enhanced with fault-tolerance features that increase the overall performance of the production system being considered. In particular, it enables tolerating (up to some degree mobile robot, processing and transportation faults. The paper discusses also robustness issues, which are inevitable in real production systems. As a result, a novel robust predictive fault-tolerant strategy is developed that is applied to the battery assembly system. The last part of the paper shows illustrative examples, which clearly exhibit the performance of the proposed approach.

  12. First reactivity determination of a subcritical reactor using a single beam-trip and fission chambers operating in current mode

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Ordonez, M.; Villamarin, D.; Becares, V.; Gonzalez-Romero, E.M. [Nuclear Innovation Group, CIEMAT, Avda. Complutense, Madrid (Spain); Bergloef, C. [Reactor Physics Department, Royal Institute of Technology, Stockholm (Sweden); Bournos, V.; Fokov, Y.; Kiyavitskaya, H. [Joint Institute for Power and Nuclear Research, National Academy of Sciences, Minsk (Belarus)

    2009-06-15

    Transmutation of spent nuclear fuel in Accelerator-Driven Systems (ADS) is considered as a key technology for achieving sustainable nuclear energy. In the design of future ADS facilities, the reactivity monitoring system is of highest importance. An extensive experimental program devoted to reactivity monitoring of ADS has been carried out at the subcritical facility YALINA-Booster in the framework of IP-EUROTRANS. The main objective, besides the qualification of the reactivity monitoring techniques, has been to develop electronic chains that can be used in a full power ADS. For this purpose, YALINA-Booster couples a D-T neutron generator to a flexible zero-power subcritical assembly with a coupled fast-thermal neutron spectrum. The high intensity of the accelerator and the possibility to work in continuous or pulsed mode allowed the study of the current-to-flux relationship and beam-trip experiments. In addition, the experimental facility provided the opportunity to test electronic chains in current mode, which correspond to the most probable condition in a full power ADS. There exists a relationship between the reactivity of a subcritical core, the intensity of the accelerator and the neutron source intensity. Hence, by monitoring these three quantities it should be possible to determine the origin of any reactivity or power change within the subcritical assembly. We have developed the necessary acquisition system to monitor the conditions of these three variables in the millisecond scale. The current-to-flux technique provides relative changes in the behavior of the core, however, in order to determine absolute values of the reactivity, we have taken profit of short imposed beam interruptions in the millisecond scale, thus providing the possibility for applying the Source-Jerk method within few milliseconds. It is the first time that the reactivity of an ADS is determined in a single beam-trip using fission chambers operating in current mode. The experiments

  13. Drop Performance Test of Conceptually Designed Control Rod Assembly for Prototype Generation IV Sodium-cooled Fast Reactor

    OpenAIRE

    Lee, Young-Kyu; Lee, Jae-Han; Kim, Hoe-Woong; Kim, Sung-Kyun; Kim, Jong-Bum

    2017-01-01

    The control rod assembly controls reactor power by adjusting its position during normal operation and shuts down chain reactions by its free drop under scram conditions. Therefore, the drop performance of the control rod assembly is important for the safety of a nuclear reactor. In this study, the drop performance of the conceptually designed control rod assembly for the prototype generation IV sodium-cooled fast reactor that is being developed at the Korea Atomic Energy Research Institute as...

  14. Interactions within the yeast t-SNARE Sso1p that control SNARE complex assembly.

    Science.gov (United States)

    Munson, M; Chen, X; Cocina, A E; Schultz, S M; Hughson, F M

    2000-10-01

    In the eukaryotic secretory and endocytic pathways, transport vesicles shuttle cargo among intracellular organelles and to and from the plasma membrane. Cargo delivery entails fusion of the transport vesicle with its target, a process thought to be mediated by membrane bridging SNARE protein complexes. Temporal and spatial control of intracellular trafficking depends in part on regulating the assembly of these complexes. In vitro, SNARE assembly is inhibited by the closed conformation adopted by the syntaxin family of SNAREs. To visualize this closed conformation directly, the X-ray crystal structure of a yeast syntaxin, Sso1p, has been determined and refined to 2.1 A resolution. Mutants designed to destabilize the closed conformation exhibit accelerated rates of SNARE assembly. Our results provide insight into the mechanism of SNARE assembly and its intramolecular and intermolecular regulation.

  15. Neutrino Physics with Accelerator Driven Subcritical Reactors

    Science.gov (United States)

    Ciuffoli, Emilio

    2017-09-01

    Accelerator Driven Subcritical System (ADS) reactors are being developed around the world, to produce energy and, at the same time, to provide an efficient way to dispose of and to recycle nuclear waste. Used nuclear fuel, by itself, cannot sustain a chain reaction; however in ADS reactors the additional neutrons which are required will be supplied by a high-intensity accelerator. This accelerator will produce, as a by-product, a large quantity of {\\bar{ν }}μ via muon Decay At Rest (µDAR). Using liquid scintillators, it will be possible to to measure the CP-violating phase δCP and to look for experimental signs of the presence of sterile neutrinos in the appearance channel, testing the LSND and MiniBooNE anomalies. Even in the first stage of the project, when the beam energy will be lower, it will be possible to produce {\\bar{ν }}e via Isotope Decay At Rest (IsoDAR), which can be used to provide competitive bounds on sterile neutrinos in the disappearance channel. I will consider several experimental setups in which the antineutrinos are created using accelerators that will be constructed as part of the China-ADS program.

  16. The Assemble and Animate Control Framework for Modular Reconfigurable Robots

    DEFF Research Database (Denmark)

    Christensen, David Johan; Schultz, Ulrik Pagh; Moghadam, Mikael

    2011-01-01

    , a library of common control and adaptation strategies, and a module abstraction layer which allows ASE to be cross-compiled for a number of different modular robotic platforms and easily ported to new platforms. In this paper we describe the design of ASE and present example applications utilizing ASE...

  17. Decant pump assembly and controls qualification testing - test report

    Energy Technology Data Exchange (ETDEWEB)

    Staehr, T.W., Westinghouse Hanford

    1996-05-02

    This report summarizes the results of the qualification testing of the supernate decant pump and controls system to be used for in-tank sludge washing in aging waste tank AZ-101. The test was successful and all components are qualified for installation and use in the tank.

  18. Production preparation and numerical control in PCB assembly

    NARCIS (Netherlands)

    van Laarhoven, P.J.M.; Zijm, Willem H.M.

    1993-01-01

    In this article, we analyze numerical control problems arising in a component insertion line for printed circuit board mounting. Such a line consists of a number of fully automated placement machines, connected by an automated, carrierless conveyor system. At each machine, the placement device

  19. Sustained and controlled release of lipophilic drugs from a self-assembling amphiphilic peptide hydrogel

    DEFF Research Database (Denmark)

    Briuglia, Maria-Lucia; Urquhart, Andrew; Lamprou, Dimitrios A.

    2014-01-01

    Materials which undergo self-assembly to form supramolecular structures can provide alternative strategies to drug loading problems in controlled release application. RADA 16 is a simple and versatile self-assembling peptide with a designed structure formed of two distinct surfaces, one hydrophilic...... and one hydrophobic that are positioned in such a well-ordered fashion allowing precise assembly into a predetermined organization. A "smart" architecture in nanostructures can represent a good opportunity to use RADA16 as a carrier system for hydrophobic drugs solving problems of drugs delivery....... In this work, we have investigated the diffusion properties of Pindolol, Quinine and Timolol maleate from RADA16 in PBS and in BSS-PLUS at 37°C. A sustained, controlled, reproducible and efficient drug release has been detected for all the systems, which allows to understand the dependence of release kinetics...

  20. Subcritical water as reaction environment: fundamentals of hydrothermal biomass transformation.

    Science.gov (United States)

    Möller, Maria; Nilges, Peter; Harnisch, Falk; Schröder, Uwe

    2011-05-23

    Subcritical water, that is, water above the boiling and below critical point, is a unique and sustainable reaction medium. Based on its solvent properties, in combination with the often considerable intrinsic water content of natural biomass, it is often considered as a potential solvent for biomass processing. Current knowledge on biomass transformation in subcritical water is, however, still rather scattered without providing a consistent picture. Concentrating on fundamental physical and chemical aspects, this review summarizes the current state of knowledge of hydrothermal biomass conversion in subcritical water. After briefly introducing subcritical water as a reaction medium, its advantages for biomass processing compared to other thermal processes are highlighted. Subsequently, the physical-chemical properties of subcritical water are discussed in the light of their impact on the occurring chemical reactions. The influence of major operational parameters, including temperature, pressure, and reactant concentration on hydrothermal biomass transformation processes are illustrated for selected carbohydrates. Major emphasis is put on the nature of the carbohydrate monomers, since the conversion of the respective polymers is analogous with the additional prior step of hydrolytic depolymerization. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Reynolds number effect on VIV: from subcritical to supercritical flow

    Energy Technology Data Exchange (ETDEWEB)

    Triantafyllou, M.S.; Hover, F.S.; Techet, A.H. [Massachusetts Inst. of Tech., Dept. of Ocean Engineering, Cambridge, MA (United States)

    2004-07-01

    Vortex Induced Vibrations in flexibly supported rigid cylinders and long, flexible slender structures, such as cables and risers, are caused by the formation of large-scale vortices, whose dynamics are controlled to a large extend by inviscid mechanisms. Reynolds number remains a very important parameter, however, because it influences the formation and shedding mechanisms of the vortical patterns. For low Reynolds numbers, below a few thousand, a nearly complete understanding has been obtained in recent years, at least for flexibly mounted rigid cylinders. This is not the case, though, for VIV above Re=10,000 and - especially - above the critical Reynolds number of about Re=250,000 for smooth cylinders. The talk provides observed WV trends of flexibly mounted cylinders, obtained in recent experiments as function of the Reynolds number, from Re about 1,000 up to 1,000,000. In particular, similarities and differences between subcritical and supercritical force and motion data will be discussed, and conclusions on the governing principal mechanisms will be drawn, including transitions in the arrangement of vortical patterns and effects of correlation length. (authors)

  2. Implementation and training methodology of subcritical reactors neutronic calculations triggered by external neutron source and applications; Implementacao e qualificacao de metodologia de calculos neutronicos em reatores subcriticos acionados por fonte externa de neutrons e aplicacoes

    Energy Technology Data Exchange (ETDEWEB)

    Carluccio, Thiago

    2011-07-01

    This works had as goal to investigate calculational methodologies on subcritical source driven reactor, such as Accelerator Driven Subcritical Reactor (ADSR) and Fusion Driven Subcritical Reactor (FDSR). Intense R and D has been done about these subcritical concepts, mainly due to Minor Actinides (MA) and Long Lived Fission Products (LLFP) transmutation possibilities. In this work, particular emphasis has been given to: (1) complement and improve calculation methodology with neutronic transmutation and decay capabilities and implement it computationally, (2) utilization of this methodology in the Coordinated Research Project (CRP) of the International Atomic Energy Agency Analytical and Experimental Benchmark Analysis of ADS and in the Collaborative Work on Use of Low Enriched Uranium in ADS, especially in the reproduction of the experimental results of the Yalina Booster subcritical assembly and study of a subcritical core of IPEN / MB-01 reactor, (3) to compare different nuclear data libraries calculation of integral parameters, such as k{sub eff} and k{sub src}, and differential distributions, such as spectrum and flux, and nuclides inventories and (4) apply the develop methodology in a study that may help future choices about dedicated transmutation system. The following tools have been used in this work: MCNP (Monte Carlo N particle transport code), MCB (enhanced version of MCNP that allows burnup calculation) and NJOY to process nuclear data from evaluated nuclear data files. (author)

  3. Guidance Navigation and Control for Autonomous Multiple Spacecraft Assembly: Analysis and Experimentation

    Directory of Open Access Journals (Sweden)

    Riccardo Bevilacqua

    2011-01-01

    Full Text Available This work introduces theoretical developments and experimental verification for Guidance, Navigation, and Control of autonomous multiple spacecraft assembly. We here address the in-plane orbital assembly case, where two translational and one rotational degrees of freedom are considered. Each spacecraft involved in the assembly is both chaser and target at the same time. The guidance and control strategies are LQR-based, designed to take into account the evolving shape and mass properties of the assembling spacecraft. Each spacecraft runs symmetric algorithms. The relative navigation is based on augmenting the target's state vector by introducing, as extra state components, the target's control inputs. By using the proposed navigation method, a chaser spacecraft can estimate the relative position, the attitude and the control inputs of a target spacecraft, flying in its proximity. The proposed approaches are successfully validated via hardware-in-the-loop experimentation, using four autonomous three-degree-of-freedom robotic spacecraft simulators, floating on a flat floor.

  4. Controlling the hydrophilicity and contact resistance of fuel cell bipolar plate surfaces using layered nanoparticle assembly

    Science.gov (United States)

    Wang, Feng

    Hybrid nanostructured coatings exhibiting the combined properties of electrical conductivity and surface hydrophilicity were obtained by using Layer-by-Layer (LBL) assembly of cationic polymer, silica nanospheres, and carbon nanoplatelets. This work demonstrates that by controlling the nanoparticle zeta (zeta) potential through the suspension parameters (pH, organic solvent type and amount, and ionic content) as well as the assembly sequence, the nanostructure and composition of the coatings may be adjusted to optimize the desired properties. Two types of silica nanospheres were evaluated as the hydrophilic component: X-TecRTM 3408 from Nano-X Corporation, with a diameter of about 20 nm, and polishing silica from Electron Microscopy Supply, with diameter of about 65 nm. Graphite nanoplatelets with a thickness of 5~10nm (Aquadag RTM E from Acheson Industries) were used as electrically conductive filler. A cationic copolymer of acrylamide and a quaternary ammonium salt (SuperflocRTM C442 from Cytec Corporation) was used as the binder for the negatively charged nanoparticles. Coatings were applied to gold-coated stainless steel substrates presently used a bipolar plate material for proton exchange membrane (PEM) fuel cells. Coating thickness was found to vary nearly linearly with the number of polymer-nanoparticle layers deposited while a monotonic increase in coating contact resistance was observed for all heterogeneous and pure silica coatings. Thickness increased if the difference in the oppositely charged zeta potentials of the adsorbing components was enhanced through alcohol addition. Interestingly, an opposite effect was observed if the zeta potential difference was increased through pH variation. This previously undocumented difference in adsorption behavior is herein related to changes to the surface chemical heterogeneity of the nanoparticles. Coating contact resistance and surface wettability were found to have a more subtle dependence on the assembly

  5. Sequential Block Copolymer Self-Assemblies Controlled by Metal-Ligand Stoichiometry.

    Science.gov (United States)

    Yin, Liyuan; Wu, Hongwei; Zhu, Mingjie; Zou, Qi; Yan, Qiang; Zhu, Liangliang

    2016-06-28

    While numerous efforts have been devoted to developing easy-to-use probes based on block copolymers for detecting analytes due to their advantages in the fields of self-assembly and sensing, a progressive response on block copolymers in response to a continuing chemical event is not readily achievable. Herein, we report the self-assembly of a 4-piperazinyl-1,8-naphthalimide based functional block copolymer (PS-b-PN), whose self-assembly and photophysics can be controlled by the stoichiometry-dependent metal-ligand interaction upon the side chain. The work takes advantages of (1) stoichiometry-controlled coordination-structural transformation of the piperazinyl moiety on PS-b-PN toward Fe(3+) ions, thereby resulting in a shrinkage-expansion conversion of the self-assembled nanostructures in solution as well as in thin film, and (2) stoichiometry-controlled competition between photoinduced electron transfer and spin-orbital coupling process upon naphthalimide fluorophore leading to a boost-decline emission change of the system. Except Fe(3+) ions, such a stoichiometry-dependent returnable property cannot be observed in the presence of other transition ions. The strategy for realizing the dual-channel sequential response on the basis of the progressively alterable nanomorphologies and emissions might provide deeper insights for the further development of advanced polymeric sensors.

  6. Controlling Self-Assembly of Engineered Peptides on Graphite by Rational Mutation

    Science.gov (United States)

    So, Christopher R.; Hayamizu, Yuhei; Yazici, Hilal; Gresswell, Carolyn; Khatayevich, Dmitriy; Tamerler, Candan; Sarikaya, Mehmet

    2012-01-01

    Self-assembly of proteins on surfaces is utilized in many fields to integrate intricate biological structures and diverse functions with engineered materials. Controlling proteins at bio-solid interfaces relies on establishing key correlations between their primary sequences and resulting spatial organizations on substrates. Protein self-assembly, however, remains an engineering challenge. As a novel approach, we demonstrate here that short dodecapeptides selected by phage display are capable of self-assembly on graphite and form long-range ordered biomolecular nanostructures. Using atomic force microscopy and contact angle studies, we identify three amino-acid domains along the primary sequence that steer peptide ordering and lead to nanostructures with uniformly displayed residues. The peptides are further engineered via simple mutations to control fundamental interfacial processes, including initial binding, surface aggregation and growth kinetics, and intermolecular interactions. Tailoring short peptides via their primary sequence offers versatile control over molecular self-assembly, resulting in well-defined surface properties essential in building engineered, chemically rich, bio-solid interfaces. PMID:22233341

  7. Application Layer Definition and Analyses of Controller Area Network Bus for Wire Harness Assembly Machine

    OpenAIRE

    Guo, Hui; Jiang, Ying

    2006-01-01

    With the feature of multi-master bus access, nondestructive contention-based arbitration and flexible configuration, Controller Area Network (CAN) bus is applied into the control system of Wire Harness Assembly Machine (WHAM). To accomplish desired goal, the specific features of the CAN bus is analyzed by compared with other field buses and the functional performances in the CAN bus system of WHAM is discussed. Then the application layer planning of CAN bus for dynamic priority is presented. ...

  8. Integrity Evaluation of Control Rod Assembly for Sodium-Cooled Fast Reactor due to Drop Impact

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Seung; Yoon, Kyung Ho; Kim, Hyung Kyu; Cheon, Jin Sik; Lee, Chan Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-03-15

    The CA (Control Assembly) of an SFR has a CRA(Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop impact. The impact analysis of the CRA under normal/abnormal drop conditions was carried out using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.

  9. Control of Self-Assembly of DNA Tubules Through Integration of Gold Nanoparticles

    Science.gov (United States)

    Sharma, Jaswinder; Chhabra, Rahul; Cheng, Anchi; Brownell, Jonathan; Liu, Yan; Yan, Hao

    2010-01-01

    The assembly of nanoparticles into three-dimensional (3D) architectures could allow for greater control of the interactions between these particles or with molecules. DNA tubes are known to form through either self-association of multi-helix DNA bundle structures or closing up of 2D DNA tile lattices. By the attachment of single-stranded DNA to gold nanoparticles, nanotubes of various 3D architectures can form, ranging in shape from stacked rings to single spirals, double spirals, and nested spirals. The nanoparticles are active elements that control the preference for specific tube conformations through size-dependent steric repulsion effects. For example, we can control the tube assembly to favor stacked-ring structures using 10-nanometer gold nanoparticles. Electron tomography revealed a left-handed chirality in the spiral tubes, double-wall tube features, and conformational transitions between tubes. PMID:19119229

  10. Quality control of FWC during assembly and commissioning in SST-1 Tokamak

    Science.gov (United States)

    Patel, Hitesh; Santra, Prosenjit; Parekh, Tejas; Biswas, Prabal; Jayswal, Snehal; Chauhan, Pradeep; Paravastu, Yuvakiran; George, Siju; Semwal, Pratibha; Thankey, Prashant; Ramesh, Gattu; Prakash, Arun; Dhanani, Kalpesh; Raval, D. C.; Khan, Ziauddin; Pradhan, Subrata

    2017-04-01

    First Wall Components (FWC) of SST-1 tokamak, which are in the immediate vicinity of plasma, comprises of limiters, divertors, baffles, passive stabilizers designed to operate long duration (∼1000 s) discharges of elongated plasma. All FWC consist of copper alloy heat sink modules with SS cooling tubes brazed onto it, graphite tiles acting as armour material facing the plasma, and are mounted to the vacuum vessels with suitable Inconel support structures at inter-connected ring & port locations. The FWC are very recently assembled and commissioned successfully inside the vacuum vessel of SST-1 undergoing a rigorous quality control and checks at every stage of the assembly process. This paper will present the quality control aspects and checks of FWC from commencement of assembly procedure, namely material test reports, leak testing of high temperature baked components, assembled dimensional tolerances, leak testing of all welded joints, graphite tile tightening torques, electrical continuity and electrical isolation of passive stabilizers from vacuum vessel, baking and cooling hydraulic connections inside vacuum vessel.

  11. Kinetic Controlled Tag-Catcher Interactions for Directed Covalent Protein Assembly.

    Science.gov (United States)

    Tan, Lee Ling; Hoon, Shawn S; Wong, Fong T

    2016-01-01

    Over the last few years, a number of different protein assembly strategies have been developed, greatly expanding the toolbox for controlling macromolecular assembly. One of the most promising developments is a rapid protein ligation approach using a short polypeptide SpyTag and its partner, SpyCatcher derived from Streptococcus pyogenes fibronectin-binding protein, FbaB. To extend this technology, we have engineered and characterized a new Tag-Catcher pair from a related fibronectin-binding protein in Streptococcus dysgalactiae. The polypeptide Tag, named SdyTag, was constructed based on the native Cna protein B-type (CnaB) domain and was found to be highly unreactive to SpyCatcher. SpyCatcher has 320-fold specificity for its native SpyTag compared to SdyTag. Similarly, SdyTag has a 75-fold specificity for its optimized Catcher, named SdyCatcherDANG short, compared to SpyCatcher. These Tag-Catcher pairs were used in combination to demonstrate specific sequential assembly of tagged proteins in vitro. We also demonstrated that the in vivo generation of circularized proteins in a Tag-Catcher specific manner where specific Tags can be left unreacted for use in subsequent ligation reactions. From the success of these experiments, we foresee the application of SdyTags and SpyTags, not only, for multiplexed control of protein assembly but also for the construction of novel protein architectures.

  12. Kinetic Controlled Tag-Catcher Interactions for Directed Covalent Protein Assembly.

    Directory of Open Access Journals (Sweden)

    Lee Ling Tan

    Full Text Available Over the last few years, a number of different protein assembly strategies have been developed, greatly expanding the toolbox for controlling macromolecular assembly. One of the most promising developments is a rapid protein ligation approach using a short polypeptide SpyTag and its partner, SpyCatcher derived from Streptococcus pyogenes fibronectin-binding protein, FbaB. To extend this technology, we have engineered and characterized a new Tag-Catcher pair from a related fibronectin-binding protein in Streptococcus dysgalactiae. The polypeptide Tag, named SdyTag, was constructed based on the native Cna protein B-type (CnaB domain and was found to be highly unreactive to SpyCatcher. SpyCatcher has 320-fold specificity for its native SpyTag compared to SdyTag. Similarly, SdyTag has a 75-fold specificity for its optimized Catcher, named SdyCatcherDANG short, compared to SpyCatcher. These Tag-Catcher pairs were used in combination to demonstrate specific sequential assembly of tagged proteins in vitro. We also demonstrated that the in vivo generation of circularized proteins in a Tag-Catcher specific manner where specific Tags can be left unreacted for use in subsequent ligation reactions. From the success of these experiments, we foresee the application of SdyTags and SpyTags, not only, for multiplexed control of protein assembly but also for the construction of novel protein architectures.

  13. Directed self-assembly of mesoscopic electronic components into sparse arrays with controlled orientation using diamagnetic levitation

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, Anton, E-mail: tkacha@rpi.edu; Lu, James J.-Q.

    2015-07-01

    This paper presents a directed self-assembly (DSA) approach for assembling small electronic components, such as semiconductor dies, into sparse 2D arrays using diamagnetic levitation. The dies attached to a diamagnetic layer can be levitated at a room temperature over a stage made of magnets arranged in a checkerboard pattern. By selecting a proper die design, levitation height, and vibration pattern of the magnetic stage we assemble the dies into a regular 2D array with a specific lateral and vertical orientation of the dies. The assembled dies are transferred to a receiving substrate using capillary force. - Highlights: • Self-assembly of semiconductor dies into arrays using diamagnetic levitation. • Control over the die orientation in vertical and lateral dimensions. • Simulation shows good scalability of assembly time with the number of dies. • Suitable for assembly of LED panels, displays and microcell photovoltaics.

  14. Microwave ion source for accelerator driven sub-critical system

    CERN Document Server

    Cui Bao Qun; Jiang Wei; LiLiQiang; WangRongWen

    2002-01-01

    A microwave ion source is under developing for a demonstration prototype of a accelerator driven sub-critical system at CIAE (China Institute of Atomic Energy), 100 mA hydrogen beam has been extracted from the source through a 7.3 mm aperture in diameter, proton ratio is more than 85%, reliability has been tested for 100 h without any failures

  15. Experimental Study of Subcritical Water Liquefaction of Biomass

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this work, hydrothermal liquefaction (HTL) of wood industry residues (wood, bark, sawdust) and macroalgae for producing biofuels has been investigated under subcritical water conditions (at temperature of 300 C), with and without the presence of catalyst. The effects of catalyst and biomass type...

  16. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    Local energy losses occur when there is a transition in open channel flow. Even though local losses in subcritical open channel flow due to changes in channel width have been studied, to date no studies have been reported for losses due to changes in bed elevations. Steps are commonly used in engineering applications ...

  17. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    2010-04-22

    7) 554-568. MORRIS HM and WIGGERT JM (1972) Applied Hydraulics in. Engineering. John Wiley & Sons, New York. ÖRSEL SI (2002) Local Losses at a Step in a Sub-critical Open. Channel Flow. M.Sc. Thesis, Department ...

  18. Extraction of antioxidants from Chlorella sp. using subcritical water treatment

    Science.gov (United States)

    Zakaria, S. M.; Mustapa Kamal, S. M.; Harun, M. R.; Omar, R.; Siajam, S. I.

    2017-06-01

    Chlorella sp. microalgae is one of the main source of natural bioactive compounds used in the food and pharmaceutical industries. Subcritical water extraction is the technique that offers an efficient, non-toxic, and environmental-friendly method to obtain natural ingredients. In this work, the extracts of Chlorella sp. microalgae was evaluated in terms of: chemical composition, extraction (polysaccharides) yield and antioxidant activity, using subcritical water extraction. Extractions were performed at temperatures ranging from 100°C to 300°C. The results show that by using subcritical water, the highest yield of polysaccharides is 23.6 that obtained at 150°C. Analysis on the polysaccharides yield show that the contents were highly influenced by the extraction temperature. The individual antioxidant activity were evaluated by in vitro assay using a free radical method. In general, the antioxidant activity of the extracts obtained at different water temperatures was high, with values of 31.08-54.29 . The results indicated that extraction by subcritical water was effective and Chlorella sp. can be a useful source of natural antioxidants.

  19. Controlled Site-Directed Assembly of Antibodies by Their Oligosaccharide Moieties onto APTES Derivatized Surfaces.

    Science.gov (United States)

    Weiping; Bin; Lei; Chunxiao; Danfeng; Fang; Chunwei; Yu

    1999-06-01

    A convenient and efficient method for the site-directed incorporation of aldehydes generated on the oligosaccharide moieties at the C-terminal of immunoglobulin (IgG) using NaIO4 oxidation reaction is explored as a means of ensuring controlled assembly of IgG antibodies onto aminopropyltriethoxylsilane (APTES) derivatized silicon wafer surfaces. The orientation and antigen binding capacity (AgBC) of site-directly assembled IgG antibodies on derivatized surfaces were investigated using atomic force microscopy (AFM) and enzyme immunoassay (EIA), respectively. A major difference in preferential orientation is observed when the incubation of derivatized surfaces with oxidized IgG molecules is compared in two different kinds of buffer solutions. We obtained the stable and homogeneous IgG layer without loss of the AgBC on the APTES derivatized surface using the controlled incubation condition. Copyright 1999 Academic Press.

  20. The dynamics of signal amplification by macromolecular assemblies for the control of chromosome segregation

    Directory of Open Access Journals (Sweden)

    Semin eLee

    2014-09-01

    Full Text Available The control of chromosome segregation relies on the spindle assembly checkpoint (SAC, a complex regulatory system that ensures the high fidelity of chromosome segregation in higher organisms by delaying the onset of anaphase until each chromosome is properly bi-oriented on the mitotic spindle. Central to this process is the establishment of multiple yet specific protein-protein interactions in a narrow time-space window. Here we discuss the highly dynamic nature of multi-protein complexes that control chromosome segregation in which an intricate network of weak but cooperative interactions modulate signal amplification to ensure a proper SAC response. We also discuss the current structural understanding of the communication between the SAC and the kinetochore; how transient interactions can regulate the assembly and disassembly of the SAC as well as the challenges and opportunities for the definition and the manipulation of the flow of information in SAC signaling.

  1. Modified hybrid control of robot manipulators for high precision assembly operations

    Science.gov (United States)

    Nguyen, Charles C.; Pooran, Farhad J.; Premack, Timothy

    1988-01-01

    This paper is concerned with applications of robot manipulators in high precision assembly tasks that can be successfully performed by employing a hybrid control scheme that independently controls force and position. A traditional hybrid control scheme is implemented in Cartesian space. In the modified hybrid control scheme introduced in this paper, the error driven control signals are expressed in joint space. This paper studies the implementation of the modified hybrid control scheme on a two-degree-of-freedom robot manipulator with a closed-kinematic chain mechanism. The performance of the traditional and modified hybrid control schemes is comparatively evaluated by computer simulation in terms of computation time and accuracy for several study cases.

  2. Orientation-controlled parallel assembly at the air-water interface

    Science.gov (United States)

    Park, Kwang Soon; Hao Hoo, Ji; Baskaran, Rajashree; Böhringer, Karl F.

    2012-10-01

    This paper presents an experimental and theoretical study with statistical analysis of a high-yield, orientation-specific fluidic self-assembly process on a preprogrammed template. We demonstrate self-assembly of thin (less than few hundred microns in thickness) parts, which is vital for many applications in miniaturized platforms but problematic for today's pick-and-place robots. The assembly proceeds row-by-row as the substrate is pulled up through an air-water interface. Experiments and analysis are presented with an emphasis on the combined effect of controlled surface waves and magnetic force. For various gap values between a magnet and Ni-patterned parts, magnetic force distributions are generated using Monte Carlo simulation and employed to predict assembly yield. An analysis of these distributions shows that a gradual decline in yield following the probability density function can be expected with degrading conditions. The experimentally determined critical magnetic force is in good agreement with a derived value from a model of competing forces acting on a part. A general set of design guidelines is also presented from the developed model and experimental data.

  3. The ribosome assembly gene network is controlled by the feedback regulation of transcription elongation.

    Science.gov (United States)

    Gómez-Herreros, Fernando; Margaritis, Thanasis; Rodríguez-Galán, Olga; Pelechano, Vicent; Begley, Victoria; Millán-Zambrano, Gonzalo; Morillo-Huesca, Macarena; Muñoz-Centeno, Mari Cruz; Pérez-Ortín, José E; de la Cruz, Jesús; Holstege, Frank C P; Chávez, Sebastián

    2017-09-19

    Ribosome assembly requires the concerted expression of hundreds of genes, which are transcribed by all three nuclear RNA polymerases. Transcription elongation involves dynamic interactions between RNA polymerases and chromatin. We performed a synthetic lethal screening in Saccharomyces cerevisiae with a conditional allele of SPT6, which encodes one of the factors that facilitates this process. Some of these synthetic mutants corresponded to factors that facilitate pre-rRNA processing and ribosome biogenesis. We found that the in vivo depletion of one of these factors, Arb1, activated transcription elongation in the set of genes involved directly in ribosome assembly. Under these depletion conditions, Spt6 was physically targeted to the up-regulated genes, where it helped maintain their chromatin integrity and the synthesis of properly stable mRNAs. The mRNA profiles of a large set of ribosome biogenesis mutants confirmed the existence of a feedback regulatory network among ribosome assembly genes. The transcriptional response in this network depended on both the specific malfunction and the role of the regulated gene. In accordance with our screening, Spt6 positively contributed to the optimal operation of this global network. On the whole, this work uncovers a feedback control of ribosome biogenesis by fine-tuning transcription elongation in ribosome assembly factor-coding genes. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  4. Surface modification and modulation in microstructures: controlling protein adsorption, monolayer desorption and micro-self-assembly

    Science.gov (United States)

    Böhringer, Karl F.

    2003-07-01

    The surface-to-volume ratio increases with decreasing scale, thus, controlling and changing the surface properties of microstructures can be a powerful tool in the design, fabrication and use of microsystems. This paper overviews several recent projects that utilize the modulation of surfaces from hydrophobic to hydrophilic and vice versa, or from protein adsorbing to non-fouling, with applications in biomedical microdevices and self-assembling microelectromechanical systems.

  5. Self-assembled polyelectrolyte complexes films as efficient compression coating layers for controlled-releasing tablets.

    Science.gov (United States)

    Li, Wenyan; Huo, Mengmeng; Sen Chaudhuri, Arka; Yang, Chen; Cao, Dazhong; Wu, Zhenghong; Qi, Xiaole

    2017-05-01

    Currently, polysaccharide-based hydrogels are widely studied macromolecular networks to modify drug dissolution from controlled-releasing matrix tablets. Among them, polyelectrolyte complexes (PEC) films consisted of chitosan (CS) and sodium alginate (SA) could be obtained via spontaneously assembling under physiological gastrointestinal environment. Here, we utilized these self-assembled PEC films as an efficient coating materials to develop controlled-released matrix tablets through compression coating process, with paracetamol (APAP) as model drug. The constitutive and morphology characteristic studies on these PEC films illustrated that the mixture of CS and SA with the weight ratio of 1:1 would be an promising outer layer for compression-coating tablets. In addition, the in vitro drug releasing behavior experiments demonstrated that the optimized compression coating tablets displayed satisfied zero-order drug releasing profits. Furthermore, the in vivo pharmacokinetic studies of these APAP loaded compression-coated tablets in New Zealand rabbits gave that the T max (12.32 ± 1.05 h) was significantly prolonged (p tablets (Jinfuning ® ) after oral administration. These studies suggest that the compression-coated tablets with self-assembled PEC film as coating outer layer may be a promising strategy for peroral controlled release delivery system of water soluble drugs.

  6. Side-chain-controlled self-assembly of polystyrene-polypeptide miktoarm star copolymers

    KAUST Repository

    Junnila, Susanna

    2012-03-27

    We show how the self-assembly of miktoarm star copolymers can be controlled by modifying the side chains of their polypeptide arms, using A 2B and A 2B 2 type polymer/polypeptide hybrids (macromolecular chimeras). Initially synthesized PS 2PBLL and PS 2PBLL 2 (PS, polystyrene; PBLL, poly(ε-tert-butyloxycarbonyl-l-lysine) ) miktoarms were first deprotected to PS 2PLLHCl and PS 2PLLHCl 2 miktoarms (PLLHCl, poly(l-lysine hydrochloride)) and then complexed ionically with sodium dodecyl sulfonate (DS) to give the supramolecular complexes PS 2PLL(DS) and PS 2(PLL(DS)) 2. The solid-state self-assemblies of these six miktoarm systems were studied by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and small- and wide-angle X-ray scattering (SAXS, WAXS). The side chains of the polypeptide arms were observed to have a large effect on the solubility, polypeptide conformation, and self-assembly of the miktoarms. Three main categories were observed: (i) lamellar self-assemblies at the block copolymer length scale with packed layers of α-helices in PS 2PBLL and PS 2PBLL 2; (ii) charge-clustered polypeptide micelles with less-defined conformations in a nonordered lattice within a PS matrix in PS 2PLLHCl and PS 2PLLHCl 2; (iii) lamellar polypeptide-surfactant self-assemblies with β-sheet conformation in PS 2PLL(DS) and PS 2(PLL(DS)) 2 which dominate over the formation of block copolymer scale structures. Differences between the 3- and 4-arm systems illustrate how packing frustration between the coil-like PS arms and rigid polypeptide conformations can be relieved by the right number of arms, leading to differences in the extent of order. © 2012 American Chemical Society.

  7. Concept and implementation of an agent-based control architecture for a cyber-physical assembly system

    Directory of Open Access Journals (Sweden)

    Müller Rainer

    2016-01-01

    Full Text Available Today’s production companies are challenged with: the assembly of different product variants with lot size of one on a single assembly line and the increase of product variants. The implementation of reconfigurable assembly systems with a modular design is a solution, which allows a flexible adaptation to different product variants. However, handling different assembly modules via specific communication protocols is limited by the current centralized control concepts. Therefore, this paper presents a concept for an agent-based control architecture. This concept uses coherent information starting from the planning process of the assembly system until the system is put into operation allowing a decentralized control. The decentralized agents in each station act as mediators between the modules and the assembly memory database enabling the product autonomous control throughout the assembly system. Moreover, the agent manages the data transfer for the modules with different specific syntaxes via respective communication protocols since a standardized communication protocol does not exist in industry. The concept is verified in a test assembly line for the production of small electronic components.

  8. Open Modular Robot Control Architecture for Assembly Using the Task Frame Formalism

    Directory of Open Access Journals (Sweden)

    Jochen Maass

    2008-11-01

    Full Text Available The task frame formalism allows the programmer to overcome the drawbacks of the traditional robot oriented assembly programming, moving the programmer's focus on the robot task. Additionally skill primitives contribute to a more natural programming paradigm. In this paper a robot control architecture is presented that implements both of these concepts providing a framework to easily implement new control features. Focus is put on a novel modular trajectory generator and the applied three-layered scheduling design. This architecture is based on the communication middleware MIRPA-X and has been experimentally validated on the HEXA parallel manipulator. The future use of distributed computing and runtime scheduling optimization are discussed.

  9. Open Modular Robot Control Architecture for Assembly Using the Task Frame Formalism

    Directory of Open Access Journals (Sweden)

    Jochen Maaß

    2006-03-01

    Full Text Available The task frame formalism allows the programmer to overcome the drawbacks of the traditional robot oriented assembly programming, moving the programmer's focus on the robot task. Additionally skill primitives contribute to a more natural programming paradigm. In this paper a robot control architecture is presented that implements both of these concepts providing a framework to easily implement new control features. Focus is put on a novel modular trajectory generator and the applied three-layered scheduling design. This architecture is based on the communication middleware MIRPA-X and has been experimentally validated on the HEXA parallel manipulator. The future use of distributed computing and runtime scheduling optimization are discussed.

  10. Dynamic control of chirality and self-assembly of double-stranded helicates with light.

    Science.gov (United States)

    Zhao, Depeng; van Leeuwen, Thomas; Cheng, Jinling; Feringa, Ben L

    2017-03-01

    Helicity switching in biological and artificial systems is a fundamental process that allows for the dynamic control of structures and their functions. In contrast to chemical approaches to responsive behaviour in helicates, the use of light as an external stimulus offers unique opportunities to invert the chirality of helical structures in a non-invasive manner with high spatiotemporal precision. Here, we report that unidirectional rotary motors with connecting oligobipyridyl ligands, which can dynamically change their chirality upon irradiation, assemble into metal helicates that are responsive to light. The motor function controls the self-assembly process as well as the helical chirality, allowing switching between oligomers and double-stranded helicates with distinct handedness. The unidirectionality of the light-induced motion governs the sequence of programmable steps, enabling the highly regulated self-assembly of fully responsive helical structures. This discovery paves the way for the future development of new chirality-dependent photoresponsive systems including smart materials, enantioselective catalysts and light-driven molecular machines.

  11. Nanoscale Control of Amyloid Self-Assembly Using Protein Phase Transfer by Host-Guest Chemistry.

    Science.gov (United States)

    Choi, Tae Su; Lee, Hong Hee; Ko, Young Ho; Jeong, Kwang Seob; Kim, Kimoon; Kim, Hugh I

    2017-07-18

    Amyloid fibrils have recently been highlighted for their diverse applications as functional nanomaterials in modern chemistry. However, tight control to obtain a targeted fibril length with low heterogeneity has not been achieved because of the complicated nature of amyloid fibrillation. Herein, we demonstrate that fibril assemblies can be homogeneously manipulated with desired lengths from ~40 nm to ~10 μm by a phase transfer of amyloid proteins based on host-guest chemistry. We suggest that host-guest interactions with cucurbit[6]uril induce a phase transfer of amyloid proteins (human insulin, human islet amyloid polypeptide, hen egg lysozyme, and amyloid-β 1-40 & 1-42) from the soluble state to insoluble state when the amount of cucurbit[6]uril exceeds its solubility limit in solution. The phase transfer of the proteins kinetically delays the nucleation of amyloid proteins, while the nuclei formed in the early stage are homogeneously assembled to fibrils. Consequently, supramolecular assemblies of amyloid proteins with heterogeneous kinetics can be controlled by protein phase transfer based on host-guest interactions.

  12. Dynamic control of chirality and self-assembly of double-stranded helicates with light

    Science.gov (United States)

    Zhao, Depeng; van Leeuwen, Thomas; Cheng, Jinling; Feringa, Ben L.

    2017-03-01

    Helicity switching in biological and artificial systems is a fundamental process that allows for the dynamic control of structures and their functions. In contrast to chemical approaches to responsive behaviour in helicates, the use of light as an external stimulus offers unique opportunities to invert the chirality of helical structures in a non-invasive manner with high spatiotemporal precision. Here, we report that unidirectional rotary motors with connecting oligobipyridyl ligands, which can dynamically change their chirality upon irradiation, assemble into metal helicates that are responsive to light. The motor function controls the self-assembly process as well as the helical chirality, allowing switching between oligomers and double-stranded helicates with distinct handedness. The unidirectionality of the light-induced motion governs the sequence of programmable steps, enabling the highly regulated self-assembly of fully responsive helical structures. This discovery paves the way for the future development of new chirality-dependent photoresponsive systems including smart materials, enantioselective catalysts and light-driven molecular machines.

  13. Quasi-chemical model of self-assembly and the formation of kinetically controlled structures

    Science.gov (United States)

    Erlikh, G. V.

    2017-04-01

    A quasi-chemical model of self-assembly among identical objects is proposed. The model rests on two main premises: (a) larger ensembles are more stable and (b) have slower rates of transformation, growth, and decomposition. These statements result from all paired interactions in the considered ensemble. This formulation of self-assembly is shown to be conducive to the formation of large ensembles with sizes distributed normally in a fairly narrow range, and with the concentrations of smaller ensembles being negligible. The existence of two critical points follows from the model. One is a critical concentration that initiates self-assembly in the system when exceeded. The other is a critical ensemble size that sets a threshold for the self-driven growth of ensembles in the system. The growth of ensembles nearly ceases at a point far from equilibrium, and the mean ensemble size and the ensemble's size distribution are under kinetic control. Stable structures of this kind (with kinetic control of their organization) can serve as models for many natural self-organized systems.

  14. Hierarchical charge distribution controls self-assembly process of silk in vitro

    Science.gov (United States)

    Zhang, Yi; Zhang, Cencen; Liu, Lijie; Kaplan, David L.; Zhu, Hesun; Lu, Qiang

    2015-12-01

    Silk materials with different nanostructures have been developed without the understanding of the inherent transformation mechanism. Here we attempt to reveal the conversion road of the various nanostructures and determine the critical regulating factors. The regulating conversion processes influenced by a hierarchical charge distribution were investigated, showing different transformations between molecules, nanoparticles and nanofibers. Various repulsion and compressive forces existed among silk fibroin molecules and aggregates due to the exterior and interior distribution of charge, which further controlled their aggregating and deaggregating behaviors and finally formed nanofibers with different sizes. Synergistic action derived from molecular mobility and concentrations could also tune the assembly process and final nanostructures. It is suggested that the complicated silk fibroin assembly processes comply a same rule based on charge distribution, offering a promising way to develop silk-based materials with designed nanostructures.

  15. Formation and geometrical control of polygon-like metal-coordination assemblies.

    Science.gov (United States)

    Maeda, Hiromitsu; Akuta, Ryo; Bando, Yuya; Takaishi, Kazuto; Uchiyama, Masanobu; Muranaka, Atsuya; Tohnai, Norimitsu; Seki, Shu

    2013-08-26

    Polygon-like [2+2]- and [3+3]-type metal complexes were prepared from dipyrrin dimers connected by acute-angled spacers. The electrical conduction depends strongly on the packing alignment of the compounds, revealing the presence of effective hopping pathways for holes with relatively high mobility up to 0.11 cm(2)  V(-1)  s(-1) along the aligned axis of [3+3]-type metal-bridged assemblies. These observations correlated with the geometrical control of the π-conjugated metal complexes in the cyclic structures, which enables their ordered arrangement in the assemblies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Novel Adaptive Sliding Mode Control with Nonlinear Disturbance Observer for SMT Assembly Machine

    Directory of Open Access Journals (Sweden)

    Rongrong Qian

    2016-01-01

    Full Text Available This paper presents a novel adaptive sliding mode control based on nonlinear sliding surface with disturbance observer (ANSMC-DOB for precision trajectory tracking control of a surface mount technology (SMT assembly machine. A two-degree-of-freedom model with time-varying parameter uncertainties and disturbances is built to describe the first axial mode of the pick-place actuation axis of the machine. According to the principle of variable damping ratio coefficient which makes the system have a nonovershoot transient response and a short settling time in the second-order system, the nonlinear sliding surface is designed for the sliding mode control (SMC. Since the upper bound value of the disturbances is unknown, the adaptive gain estimation is applied to replace the switching gain in the SMC. In order to settle the problem of SMC unrobust to the mismatched parameter uncertainties and disturbances, the nonlinear disturbance observer is introduced to estimate the mismatched disturbances and form the novel controller of ANSMC-DOB. The stability of sliding surfaces and control laws are verified by the Lyapunov functions. The simulation research and comparative experiments are conducted to verify the improvement of positioning accuracy and robustness by the proposed ANSMC-DOB in the SMT assembly machine.

  17. Quality characteristic association analysis of computer numerical control machine tool based on meta-action assembly unit

    Directory of Open Access Journals (Sweden)

    Yan Ran

    2016-01-01

    Full Text Available As everyone knows, assembly quality plays a very important role in final product quality. Since computer numerical control machine tool is a large system with complicated structure and function, and there are complex association relationships among quality characteristics in assembly process, then it is difficult and inaccurate to analyze the whole computer numerical control machine tool quality characteristic association at one time. In this article, meta-action assembly unit is proposed as the basic analysis unit, of which quality characteristic association is studied to guarantee the whole computer numerical control machine tool assembly quality. First, based on “Function-Motion-Action” decomposition structure, the definitions of meta-action and meta-action assembly unit are introduced. Second, manufacturing process association and meta-action assembly unit quality characteristic association are discussed. Third, after understanding the definitions of information entropy and relative entropy, the concrete meta-action assembly unit quality characteristic association analysis steps based on relative entropy are described in detail. And finally, the lifting piston translation assembly unit of automatic pallet changer is taken as an example, the association degree between internal leakage and the influence factors of part quality characteristics and mate-relationships among them are calculated to figure out the most influential factors, showing the correctness and feasibility of this method.

  18. Study in stationary state of the subcriticality of intermediate configurations of core in the reloading process of a BWR; Estudio en estado estacionario de la subcriticidad de configuraciones intermedias de nucleo en el proceso de recarga de un BWR

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, J.L.; Montes, J.L.; Perusquia, R.; Ortiz, J.J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: jlhm@nuclear.inin.mx

    2006-07-01

    In this work is carried out the simulation in three dimensions with the COREMASTER-PRESTO code, of the behavior of the reactor core in different stages of the change process of fuel assemblies. To carry out the simulation, this code requires of a database of nuclear parameters that includes those that can associate to the areas of an assemblies that they don't contain fuel and in its place there is moderator. These nuclear parameters are calculated with the AURORA-HELIOS-ZENITH-TABGEN system. One of the approaches that were carried out consisted on designing a 'water assemble', that is to say, an axial arrangement of 25 'water cells'. To obtain the appropriate 'water cell' its were carried out some selective test cases, since it presents in two cases the necessity to find an enough minimum value of fissile material for the correct execution of HELIOS, firstly, and later on COREMASTER-PRESTO. In the first case, the situation is solved when placing symmetrically 6 bars with natural uranium in the lateral areas of the cell; with that which the value of k{sub inf} of 0.1592 is obtained in the calculations with the HELIOS code in the cold condition to zero power (CZP), and 0% of vacuums. For the second case the cell includes symmetrically 28 bars with natural uranium, and the k{sub inf} value is 0.45290. These values are the maximum through the life of the 'cell.' As part of the activities that are developed during the fuel substitution, this the one of evaluating the subcriticality of the core each determined number of substitution movements. The obtained results when evaluating the k-effective in cold condition, in 5 different intermediate core configurations, as the loading process of the fuel advances are presented. To make the evaluation with CM-PRESTO in each configuration it was proceeded to complete the rest of the 444 assemblies with the one denominated 'water assemble'. In all the evaluated cases the

  19. SUB-LEU-METAL-THERM-001 SUBCRITICAL MEASUREMENTS OF LOW ENRICHED TUBULAR URANIUM METAL FUEL ELEMENTS BEFORE & AFTER IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    TOFFER, H.

    2006-07-18

    With the shutdown of the Hanford PUREX (Plutonium-Uranium Extraction Plant) reprocessing plant in the 1970s, adequate storage capacity for spent Hanford N Reactor fuel elements in the K and N Reactor pools became a concern. To maximize space utilization in the pools, accounting for fuel burnup was considered. Fuel that had experienced a neutron environment in a reactor is known as spent, exposed, or irradiated fuel. In contrast fuel that has not yet been placed in a reactor is known as green, unexposed, or unirradiated fuel. Calculations indicated that at typical fuel exposures for N Reactor, the spent-fuel critical mass would be twice the critical mass for green fuel. A decision was reached to test the calculational result with a definitive experiment. If the results proved positive, storage capacity could be increased and N Reactor operation could be prolonged. An experiment to be conducted in the N Reactor spent-fuel storage pool was designed and assembled (References 1 and 2) and the services of the Battelle Northwest Laboratories (BNWL) (now Pacific Northwest National Laboratory [PNNL]) critical mass laboratory were procured for the measurements (Reference 3). The experiments were performed in April 1975 in the Hanford N Reactor fuel storage pool. The fuel elements were MKIA fuel assemblies, comprised of two concentric tubes of low-enriched metallic uranium. Two separate sets of measurements were performed: one with unirradiated fuel and one with irradiated fuel. Both the unirradiated and irradiated fuel, were measured in the same geometry. The spent-fuel MKIA assemblies had an average burnup of 2865 MWd (megawatt days)/t. A constraint was imposed restricting the measurements to a subcritical limit of k{sub eff} = 0.97. Subcritical count rate data was obtained with pulsed-neutron and approach-to-critical measurements. Ten (10) configurations with green fuel and nine (9) configurations with spent fuel are described and evaluated. Of these, three (3) green fuel

  20. Self-assembling peptide nanofiber scaffolds for controlled release governed by gelator design and guest size.

    Science.gov (United States)

    Zhao, Ying; Tanaka, Masayoshi; Kinoshita, Takatoshi; Higuchi, Masahiro; Tan, Tianwei

    2010-11-01

    The aim of this study was to develop controlled drug delivery by network scaffolds based on self-assembling peptide RADAFI and RADAFII. These two peptides self-assembled into interconnected nanofibrilar network structures with distinct physical morphologies. The hydrogels were also utilized for entrapment and release of some model guests, promising their future application as a drug delivery vehicle. Fickian diffusion controlled the release kinetics. Furthermore, the obtained release function was dependent on both rational design of the peptides used for hydrogel formation and choice of the entrapped molecules. On the basis of the striking different releases of these two peptide scaffolds, we suggested that guest size and lipophilicity influenced the release competitively. The release of RADAFI system was dominated by guest size, and the guest lipophilicity controlled the release behavior in RADAFII system. In a word, this work would potentially provide a spatially and temporally controlled delivery system for some functional drugs in the future. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Fluid-Mediated Stochastic Self-Assembly at Centimetric and Sub-Millimetric Scales: Design, Modeling, and Control

    National Research Council Canada - National Science Library

    Haghighat, Bahar; Mastrangeli, Massimo; Mermoud, Grégory; Schill, Felix; Martinoli, Alcherio

    2016-01-01

    .... Numerous studies have been conducted on the control and modeling of the process in engineered self-assembling systems constituted of modules with varied capabilities ranging from completely reactive...

  2. Predistortion control device and method, assembly including a predistortion control device

    NARCIS (Netherlands)

    Kokkeler, Andre B.J.

    2003-01-01

    A predistortion control device (1). The device has a first predistortion control input connectable to a power amplifier output (21); a second predistortion control input (11) connectable to a signal contact of a predistortion device; and a predistortion control output (12) connectable to a control

  3. Drop Performance Test of Conceptually Designed Control Rod Assembly for Prototype Generation IV Sodium-Cooled Fast Reactor

    Directory of Open Access Journals (Sweden)

    Young-Kyu Lee

    2017-06-01

    Full Text Available The control rod assembly controls reactor power by adjusting its position during normal operation and shuts down chain reactions by its free drop under scram conditions. Therefore, the drop performance of the control rod assembly is important for the safety of a nuclear reactor. In this study, the drop performance of the conceptually designed control rod assembly for the prototype generation IV sodium-cooled fast reactor that is being developed at the Korea Atomic Energy Research Institute as a next-generation nuclear reactor was experimentally investigated. For the performance test, the test facility and test procedure were established first, and several free drop performance tests of the control rod assembly under different flow rate conditions were then carried out. Moreover, performance tests under several types and magnitudes of seismic loading conditions were also conducted to investigate the effects of seismic loading on the drop performance of the control rod assembly. The drop time of the conceptually designed control rod assembly for 0% of the tentatively designed flow rate was measured to be 1.527 seconds, and this agrees well with the analytically calculated drop time. It was also observed that the effect of seismic loading on the drop time was not significant.

  4. The imprint of the Hawking effect in subcritical flows

    CERN Document Server

    Coutant, Antonin

    2016-01-01

    We study the propagation of low frequency shallow water waves on a one dimensional flow of varying depth. When taking into account dispersive effects, the linear propagation of long wavelength modes on uneven bottoms excites new solutions of the dispersion relation which possess a much shorter wavelength. The peculiarity is that one of these new solutions has a negative energy. When the flow becomes supercritical, this mode has been shown to be responsible for the (classical) analog of the Hawking effect. For subcritical flows, the production of this mode has been observed numerically and experimentally, but the precise physics governing the scattering remained unclear. In this work, we provide an analytic treatment of this effect in subcritical flows. We analyze the scattering of low frequency waves using a new perturbative series, derived from a generalization of the Bremmer series. We show that the production of short wavelength modes is governed by a complex value of the position: a complex turning point....

  5. A microfluidic sub-critical water extraction instrument

    Science.gov (United States)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

    2017-11-01

    This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

  6. Stimuli-controlled self-assembly of diverse tubular aggregates from one single small monomer

    Science.gov (United States)

    Shi, Qixun; Javorskis, Tomas; Bergquist, Karl-Erik; Ulčinas, Artūras; Niaura, Gediminas; Matulaitienė, Ieva; Orentas, Edvinas; Wärnmark, Kenneth

    2017-04-01

    The design and synthesis of new stimuli-responsive hydrogen-bonding monomers that display a diversity of self-assembly pathways is of central importance in supramolecular chemistry. Here we describe the aggregation properties of a simple, intrinsically C2-symmetric enantiopure bicyclic cavity compound bearing a terminally unsubstituted ureidopyrimidinone fragment fused with a pyrrole moiety in different solvents and in the absence and presence of C60 and C70 guests. The tetrameric cyclic aggregate is selectively obtained in chlorinated solvents, where only part of the available hydrogen bonding sites are utilized, whereas in toluene or upon addition of C70 guests, further aggregation into tubular supramolecular polymers is achieved. The open-end cyclic assemblies rearrange into a closed-shell capsule upon introduction of C60 with an accompanied symmetry breaking of the monomer. Our study demonstrates that a C60 switch can be used to simultaneously control the topology and occupancy of tubular assemblies resulting from the aggregation of small monomers.

  7. Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

    Science.gov (United States)

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

    2017-02-01

    The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

  8. Controlled Solution Self-Assembly of a Midblock-Sulfonated Pentablock Copolymer

    Science.gov (United States)

    Mineart, Kenneth; Gradzielski, Michael; Spontak, Richard

    The solution self-assembly of midblock-sulfonated block ionomers (SBIs) has been shown to translate to their bulk, solution-cast morphology, which can further impact their function in applications such as desalination, fuel cell, and photovoltaic membranes. Previous studies have identified that increasing the degree of sulfonation (DOS) in SBIs dispersed in a nonpolar solvent results in the growth of micellar aggregates due to increased interfacial energy. However, these works have not attempted to control the assembly at a given DOS by tuning the solvent environment. The current study probes the tunability of SBI aggregation behavior using a nonpolar/polar solvent mixture varying in composition. A combination of light scattering (SLS and DLS) and small angle X-ray scattering (SAXS) independently confirm that SBI micelles grow larger, both in core and corona, as the solvent environment becomes more nonpolar. The increases in both core and corona size will be explained using polymer thermodynamics and further supported through presentation of small angle neutron scattering (SANS) data. In addition, these results will be compared with SBI self-assembly in a single solvent, which is expected to distribute between the micelle cores and bulk solvent environment. We would like to acknowledge funding from NSF IRES (App #1065466) and MANN+HUMMEL GmbH.

  9. Ligand functionality as a versatile tool to control the assembly behavior of preformed titania nanocrystals.

    Science.gov (United States)

    Polleux, Julien; Pinna, Nicola; Antonietti, Markus; Hess, Christian; Wild, Ute; Schlögl, Robert; Niederberger, Markus

    2005-06-06

    Nanoparticle powders composed of surface-functionalized anatase crystals with diameters of about 3 nm self-organize into different structures upon redispersion in water. The assembly is directed by a small amount of a low-molecular-weight functional ligand (the "assembler") adsorbed on the surface of the nanoparticles. The ligand functionality determines the anisotropy of the resulting structures. Multidentate ligands, such as trizma ((HOCH(2))(3)CNH(2)) and serinol ((HOCH(2))(2)CNH(2)), with a chargeable terminal group preferentially induce the formation of anisotropic nanostructures several hundreds of nanometers in total length, whereas all the other investigated ligands (ethanolamine H(2)N(CH(2))(2)OH, glycine hydroxamate H(2)NCH(2)CONHOH, dopamine (OH)(2)C(6)H(3)(CH(2))(2)NH(3)Cl, tris (HOCH(2))(3)CCH(3)) mainly lead to uncontrolled agglomeration. Experimental data suggests that the anisotropic assembly is a consequence of the water-promoted desorption of the organic ligands from the {001} faces of the crystalline building blocks together with the dissociative adsorption of water on these crystal faces. Both processes induce the preferred attachment of the titania nanoparticles along the [001] direction. The use of polydentate and charged ligands to functionalize the surface of nanoparticles thus provides a versatile tool to control their arrangement on the nanoscale.

  10. A simple proof of exponential decay of subcritical contact processes

    Czech Academy of Sciences Publication Activity Database

    Swart, Jan M.

    2018-01-01

    Roč. 170, 1-2 (2018), s. 1-9 ISSN 0178-8051 R&D Projects: GA ČR(CZ) GA16-15238S Institutional support: RVO:67985556 Keywords : subcritical contact process * sharpness of the phase transition * eigenmeasure Subject RIV: BA - General Mathematics Impact factor: 1.895, year: 2016 http:// library .utia.cas.cz/separaty/2016/SI/swart-0462694.pdf

  11. Development and Investigation of Reactivity Measurement Methods in Subcritical Cores

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Johanna

    2005-05-01

    Subcriticality measurements during core loading and in future accelerator driven systems have a clear safety relevance. In this thesis two subcriticality methods are treated: the Feynman-alpha and the source modulation method. The Feynman-alpha method is a technique to determine the reactivity from the relative variance of the detector counts during a measurement period. The period length is varied to get the full time dependence of the variance-to-mean. The corresponding theoretical formula was known only with stationary sources. In this thesis, due to its relevance for novel reactivity measurement methods, the Feynman-alpha formulae for pulsed sources for both the stochastic and the deterministic cases are treated. Formulae neglecting as well as including the delayed neutrons are derived. The formulae neglecting delayed neutrons are experimentally verified with quite good agreement. The second reactivity measurement technique investigated in this thesis is the so-called source modulation technique. The theory of the method was elaborated on the assumption of point kinetics, but in practice the method will be applied by using the signal from a single local neutron detector. Applicability of the method therefore assumes point kinetic behaviour of the core. Hence, first the conditions of the point kinetic behaviour of subcritical cores was investigated. After that the performance of the source modulation technique in the general case as well as and in the limit of exact point kinetic behaviour was examined. We obtained the unexpected result that the method has a finite, non-negligible error even in the limit of point kinetic behaviour, and a substantial error in the operation range of future accelerator driven subcritical reactors (ADS). In practice therefore the method needs to be calibrated by some other method for on-line applications.

  12. Weak competing interactions control assembly of strongly bonded TCNQ ionic acceptor molecules on silver surfaces

    Science.gov (United States)

    Park, Changwon; Rojas, Geoffrey A.; Jeon, Seokmin; Kelly, Simon J.; Smith, Sean C.; Sumpter, Bobby G.; Yoon, Mina; Maksymovych, Petro

    2014-09-01

    The energy scales of interactions that control molecular adsorption and assembly on surfaces can vary by several orders of magnitude, yet the importance of each contributing interaction is not apparent a priori. Tetracyanoquinodimethane (TCNQ) is an archetypal electron acceptor molecule and it is a key component of organic metals. On metal surfaces, this molecule also acts as an electron acceptor, producing negatively charged adsorbates. It is therefore rather intriguing to observe attractive molecular interactions in this system that were reported previously for copper and silver surfaces. Our experiments compared TCNQ adsorption on noble metal surfaces of Ag(100) and Ag(111). In both cases we found net attractive interactions down to the lowest coverage. However, the morphology of the assemblies was strikingly different, with two-dimensional islands on Ag(100) and one-dimensional chains on Ag(111) surfaces. This observation suggests that the registry effect governed by the molecular interaction with the underlying lattice potential is critical in determining the dimensionality of the molecular assembly. Using first-principles density functional calculations with a van der Waals correction scheme, we revealed that the strengths of major interactions (i.e., lattice potential corrugation, intermolecular attraction, and charge-transfer-induced repulsion) are all similar in energy. The van der Waals interactions, in particular, almost double the strength of attractive interactions, making the intermolecular potential comparable in strength to the diffusion potential and promoting self-assembly. However, it is the anisotropy of local intermolecular interactions that is primarily responsible for the difference in the topology of the molecular islands on Ag(100) and Ag(111) surfaces. We anticipate that the intermolecular potential will become more attractive and dominant over the diffusion potential with increasing molecular size, providing new design strategies for the

  13. Conducting nanowires built by controlled self-assembly of amyloid fibers and selective metal deposition

    Science.gov (United States)

    Scheibel, Thomas; Parthasarathy, Raghuveer; Sawicki, George; Lin, Xiao-Min; Jaeger, Heinrich; Lindquist, Susan L.

    2003-04-01

    Recent research in the field of nanometer-scale electronics has focused on the operating principles of small-scale devices and schemes to realize useful circuits. In contrast to established "top-down" fabrication techniques, molecular self-assembly is emerging as a "bottom-up" approach for fabricating nanostructured materials. Biological macromolecules, especially proteins, provide many valuable properties, but poor physical stability and poor electrical characteristics have prevented their direct use in electrical circuits. Here we describe the use of self-assembling amyloid protein fibers to construct nanowire elements. Self-assembly of a prion determinant from Saccharomyces cerevisiae, the N-terminal and middle region (NM) of Sup35p, produced 10-nm-wide protein fibers that were stable under a wide variety of harsh physical conditions. Their lengths could be roughly controlled by assembly conditions in the range of 60 nm to several hundred micrometers. A genetically modified NM variant that presents reactive, surface-accessible cysteine residues was used to covalently link NM fibers to colloidal gold particles. These fibers were placed across gold electrodes, and additional metal was deposited by highly specific chemical enhancement of the colloidal gold by reductive deposition of metallic silver and gold from salts. The resulting silver and gold wires were 100 nm wide. These biotemplated metal wires demonstrated the conductive properties of a solid metal wire, such as low resistance and ohmic behavior. With such materials it should be possible to harness the extraordinary diversity and specificity of protein functions to nanoscale electrical circuitry.

  14. Intelligent controller of a flexible hybrid robot machine for ITER assembly and maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Al-saedi, Mazin I., E-mail: mazin.al-saedi@lut.fi; Wu, Huapeng; Handroos, Heikki

    2014-10-15

    Highlights: • Studying flexible multibody dynamic of hybrid parallel robot. • Investigating fuzzy-PD controller to control a hybrid flexible hydraulically driven robot. • Investigating ANFIS-PD controller to control a hybrid flexible robot. Compare to traditional PID this method gives better performance. • Using the equilibrium of reaction forces between the parallel and serial parts of hybrid robot to control the serial part hydraulically driven. - Abstract: The assembly and maintenance of International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is highly challenging since the tasks performed by the robot involve welding, material handling, and machine cutting from inside the VV. To fulfill the tasks in ITER application, this paper presents a hybrid redundant manipulator with four DOFs provided by serial kinematic axes and six DOFs by parallel mechanism. Thus, in machining, to achieve greater end-effector trajectory tracking accuracy for surface quality, a robust control of the actuators for the flexible link has to be deduced. In this paper, the intelligent control of a hydraulically driven parallel robot part based on the dynamic model and two control schemes have been investigated: (1) fuzzy-PID self tuning controller composed of the conventional PID control and with fuzzy logic; (2) adaptive neuro-fuzzy inference system-PID (ANFIS-PID) self tuning of the gains of the PID controller, which are implemented independently to control each hydraulic cylinder of the parallel robot based on rod position predictions. The obtained results of the fuzzy-PID and ANFIS-PID self tuning controller can reduce more tracking errors than the conventional PID controller. Subsequently, the serial component of the hybrid robot can be analyzed using the equilibrium of reaction forces at the universal joint connections of the hexa-element. To achieve precise positional control of the end effector for maximum precision machining, the hydraulic cylinder should

  15. Controllable coordination-driven self-assembly: from discrete metallocages to infinite cage-based frameworks.

    Science.gov (United States)

    Chen, Lian; Chen, Qihui; Wu, Mingyan; Jiang, Feilong; Hong, Maochun

    2015-02-17

    CONSPECTUS: Nanosized supramolecular metallocages have a unique self-assembly process that allows chemists to both understand and control it. In addition, well-defined cavities of such supramolecular aggregates have various attractive applications including storage, separation, catalysis, recognition, drug delivery, and many others. Coordination-driven self-assembly of nanosized supramolecular metallocages is a powerful methodology to construct supramolecular metallocages with considerable size and desirable shapes. In this Account, we summarize our recent research on controllable coordination-driven assembly of supramolecular metallocages and infinite cage-based frameworks. To this end, we have chosen flexible ligands that can adopt various conformations and metal ions with suitable coordination sites for the rational design and assembly of metal-organic supramolecular ensembles. This has resulted in various types of metallocages including M3L2, M6L8, M6L4, and M12L8 with different sizes and shapes. Because the kinds of metal geometries are limited, we have found that we can replace single metal ions with metal clusters to alternatively increase molecular diversity and complexity. There are two clear-cut merits of this strategy. First, metal clusters are much bigger than single metal ions, which helps in the construction and stabilization of large metallocages, especially nanosized cages. Second, metal clusters can generate diverse assembly modes that chemists could not synthesize with single metal ions. This allows us to obtain a series of unprecedented supramolecular metallocages. The large cavities and potential unsaturated coordination sites of these discrete supramolecular cages offer opportunities to construct infinite cage-based frameworks. This in turn can offer us a new avenue to understand self-assembly and realize certain various functionalities. We introduce two types of infinite cage-based frameworks here: cage-based coordination polymers and cage

  16. Controlled Ordering of Long-range Perpendicular Lamellae by Block Copolymer Self-assembly

    Science.gov (United States)

    Ryu, Du Yeol; Kim, Kyunginn; Park, Sungmin; Kim, Yeongsik; Yonsei Univ Team

    We introduce a simple approach to fabricating highly stable, perpendicularly oriented lamellae through the self-assembly of high-molecular-weight polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA). The desired morphology was achieved over a narrow annealing period (5 10 min) under solvent vapor, since the SVA process need to terminate immediately before the saturated BCP films begin to dewet the substrate. This narrow processing period impeded practical applications to continuous industrial processes. A controlled SVA process at a selected temperature gap was found to show the excellent long-term stability, at which highly ordered line-arrays of perpendicularly oriented lamellae were confined to topographic line patterns.

  17. Domain Size Control in Self-Assembling Rod-Coil Block Copolymer And Homopolymer Blends

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Y.; Olsen, B.D.; Ganesan, V.; Segalman, R.A.; /UC, Berkeley /LBL, Berkeley /Texas U.

    2007-07-13

    The addition of homopolymers to a self-assembling rod-coil block copolymer is demonstrated to be a flexible route toward domain size control. Molecular weight matched rod-like homopolymers interdigitate with the rod-blocks within their respective lamellae. As a result of the interdigitation, the coil blocks must rearrange to occupy more interfacial area resulting in an unprecedented decrease in domain spacing with increasing rod homopolymers. Conversely coil homopolymers were locally solubilized within the coil microdomain resulting in an increase of domain spacing with increasing coil homopolymers. The mechanisms of homopolymers solubilization are in qualitative agreement with predictions made by self-consistent mean-field theory (SCFT) calculations.

  18. Optical control of electron spin qubit in InAs self-assembled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Emary, Clive [TU Berlin, Sekr. PN 7-1, Institut fuer Theoretische Physik, Hardenbergstr. 36, D-10623 Berlin (Germany); Sham, Lu Jeu [Department of Physics, University of California San Diego, La Jolla, California 92093 (United States)

    2008-07-01

    The spin of an electron trapped in a self-assembled quantum dot is viewed as a promising quantum bit. We present here a theory of the control of such qubits using short laser pulses to excite virtual trion states within the dots. We describe mechanisms for qubit initialisation and for performing universal one and two qubit operations. We show that, for InAs dots, initialisation can be achieved on the nanosecond time-scale, and that coherent operations can performed with laser pulses with durations of tens of picoseconds. These results are of direct relevance to current experiments.

  19. Controlled nanodimensional supramolecular self-assembly of tetra-alkylated naphthalene diimide derivatives.

    Science.gov (United States)

    Bhosale, Sheshanath V; Ghule, Namdev V; Al Kobaisi, Mohammad; Kelson, Melissa M A; Bhosale, Sidhanath V

    2014-08-18

    Construction of thermodynamically stable nanostructures on the nano- to millimeter scales through noncovalent bonding plays an important role in material science. The self-assembly of tetra-alkylamino core-substituted naphthalene diimides (cNDIs) with variable alkyl chains (C8H17, C12H25, and C16H33) added on to the core leads to the formation of a variety of controlled morphologies and well-defined nanostructures. Such structures include nanorods, vesicular, belts, twisted ribbons, and donutlike morphologies (formed in CHCl3/MeOH and CHCl3/hexane mixtures) generated through solvophobic control. UV/Vis absorption and fluorescence spectroscopy demonstrate molecular aggregation in solution. Furthermore, SEM was employed to visualize the supramolecular self-assembled nanostructures. The growth of these structures is mainly due to packing of hydrophobic alkyl chains and π-π stacking of the cNDI core. The present study paves the way to rational and controlled designs of nanostructures made of optically active dyes (naphthalene diimide); this may open a new avenue towards tuning nanodimensional morphology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Femtosecond Laser-Controlled Tip-to-Tip Assembly and Welding of Gold Nanorods.

    Science.gov (United States)

    González-Rubio, Guillermo; González-Izquierdo, Jesús; Bañares, Luis; Tardajos, Gloria; Rivera, Antonio; Altantzis, Thomas; Bals, Sara; Peña-Rodríguez, Ovidio; Guerrero-Martínez, Andrés; Liz-Marzán, Luis M

    2015-12-09

    Directed assembly of gold nanorods through the use of dithiolated molecular linkers is one of the most efficient methodologies for the morphologically controlled tip-to-tip assembly of this type of anisotropic nanocrystals. However, in a direct analogy to molecular polymerization synthesis, this process is characterized by difficulties in chain-growth control over nanoparticle oligomers. In particular, it is nearly impossible to favor the formation of one type of oligomer, making the methodology hard to use for actual applications in nanoplasmonics. We propose here a light-controlled synthetic procedure that allows obtaining selected plasmonic oligomers in high yield and with reaction times in the scale of minutes by irradiation with low fluence near-infrared (NIR) femtosecond laser pulses. Selective inhibition of the formation of gold nanorod n-mers (trimers) with a longitudinal localized surface plasmon in resonance with a 800 nm Ti:sapphire laser, allowed efficient trapping of the (n - 1)-mers (dimers) by hot spot mediated photothermal decomposition of the interparticle molecular linkers. Laser irradiation at higher energies produced near-field enhancement at the interparticle gaps, which is large enough to melt gold nanorod tips, offering a new pathway toward tip-to-tip welding of gold nanorod oligomers with a plasmonic response at the NIR. Thorough optical and electron microscopy characterization indicates that plasmonic oligomers can be selectively trapped and welded, which has been analyzed in terms of a model that predicts with reasonable accuracy the relative concentrations of the main plasmonic species.

  1. Beam transient analyses of Accelerator Driven Subcritical Reactors based on neutron transport method

    Energy Technology Data Exchange (ETDEWEB)

    He, Mingtao; Wu, Hongchun [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Wang, Kunpeng [Nuclear and Radiation Safety Center, PO Box 8088, Beijing 100082 (China); Li, Xunzhao; Zhou, Shengcheng [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China)

    2015-12-15

    Highlights: • A transport-based kinetics code for Accelerator Driven Subcritical Reactors is developed. • The performance of different kinetics methods adapted to the ADSR is investigated. • The impacts of neutronic parameters deteriorating with fuel depletion are investigated. - Abstract: The Accelerator Driven Subcritical Reactor (ADSR) is almost external source dominated since there is no additional reactivity control mechanism in most designs. This paper focuses on beam-induced transients with an in-house developed dynamic analysis code. The performance of different kinetics methods adapted to the ADSR is investigated, including the point kinetics approximation and space–time kinetics methods. Then, the transient responds of beam trip and beam overpower are calculated and analyzed for an ADSR design dedicated for minor actinides transmutation. The impacts of some safety-related neutronics parameters deteriorating with fuel depletion are also investigated. The results show that the power distribution varying with burnup leads to large differences in temperature responds during transients, while the impacts of kinetic parameters and feedback coefficients are not very obvious. Classification: Core physic.

  2. The Free Overfall in Circular Sections with Different Flat Base in Supercritical and Subcritical Flow Regimes

    Directory of Open Access Journals (Sweden)

    A.R. Vatankhah

    2017-01-01

    Full Text Available Introduction: A free overfall offers a simple device for flow discharge measuring by a single measurement of depth at the end of the channel yb which is known as the end depth or brink depth. When the bottom of a channel drops suddenly, the flow separates from sharp edge of the brink and the pressure distribution is not hydrostatic because of the curvature of the flow. In channels with subcritical flow regime, control section occurs at the upstream with a critical depth (yc. Although pressure distribution at the critical depth is hydrostatic, the location of the critical depth can vary with respect to the discharge value. So, the end depth at brink is offered to estimate the discharge. A unique relationship between the brink depth (yb and critical depth (yc, known as end-depth ratio (EDR = yb/yc, exist. Since a relationship between the discharge and critical depth exists, the discharge can ultimately be related to yb. However, when the approaching flow is supercritical, critical section does not exist. Therefore, the discharge will be a function of end depth and channel longitudinal slope. In current study, an analytical model is presented for a circular free overfall with different flat base height in subcritical and supercritical flow regimes. The flow over a drop in a free overfall is simulated by applying the energy to calculate the EDR and end depth-discharge (EDD relationship. End-depth-discharge relationship: The flow of a free overfall in a channel can be assumed that is similar to the flow over a sharp-crested weir by taking weir height equal to zero. It is assumed that pressure at the end section is atmospheric, and also streamlines at the end section are parallel. To account for the curvature of streamlines, the deflection of jet due to gravity, the coefficient of contraction, Cc, is considered. At a short distance upstream the end section, the pressure is hydrostatic. By applying the energy equation between end section and control

  3. Subcritical water extraction of amino acids from Mars analog soils.

    Science.gov (United States)

    Noell, Aaron C; Fisher, Anita M; Fors-Francis, Kisa; Sherrit, Stewart

    2018-01-18

    For decades, the Martian regolith has stymied robotic mission efforts to catalog the organic molecules present. Perchlorate salts, found widely throughout Mars, are the main culprit as they breakdown and react with organics liberated from the regolith during pyrolysis, the primary extraction technique attempted to date on Mars. This work further develops subcritical water extraction (SCWE) as a technique for extraction of amino acids on future missions. The effect of SCWE temperature (185, 200, and 215°C) and duration of extraction (10-120 min) on the total amount and distribution of amino acids recovered was explored for three Mars analog soils (JSC Mars-1A simulant, an Atacama desert soil, and an Antarctic Dry Valleys soil) and bovine serum albumin (as a control solution of known amino acid content). Total amounts of amino acids extracted increased with both time and temperature; however, the distribution shifted notably due to the destruction of the amino acids with charged or polar side chains at the higher temperatures. The pure bovine serum albumin solution and JSC Mars 1A also showed lower yields than the Atacama and Antarctic extractions suggesting that SCWE may be less effective at hydrolyzing large or aggregated proteins. Changing solvent from water to a dilute (10 mM) HCl solution allowed total extraction efficiencies comparable to the higher temperature/time combinations while using the lowest temperature/time (185°C/20 min). The dilute HCl extractions also did not lead to the shift in amino acid distribution observed at the higher temperatures. Additionally, adding sodium perchlorate salt to the extraction did not interfere with recoveries. Native magnetite in the JSC Mars-1A may have been responsible for destruction of glycine, as evidenced by its uncharacteristic decrease as the temperature/time of extraction increased. This work shows that SCWE can extract high yields of native amino acids out of Mars analog soils with minimal disruption of the

  4. Control of the hierarchical assembly of π-conjugated optoelectronic peptides by pH and flow.

    Science.gov (United States)

    Mansbach, Rachael A; Ferguson, Andrew L

    2017-07-05

    Self-assembled nanoaggregates of π-conjugated peptides possess optoelectronic properties due to electron delocalization over the conjugated peptide groups that make them attractive candidates for the fabrication of bioelectronic materials. We present a computational and theoretical study to resolve the microscopic effects of pH and flow on the non-equilibrium morphology and kinetics of early-stage assembly of an experimentally-realizable optoelectronic peptide that displays pH triggerable assembly. Employing coarse-grained molecular dynamics simulations, we probe the effects of pH on growth kinetics and aggregate morphology to show that control of the peptide protonation state by pH can be used to modulate the assembly rates, degree of molecular alignment, and resulting morphologies within the self-assembling nanoaggregates. We also quantify the time and length scales at which convective flows employed in directed assembly compete with microscopic diffusion to show that flow influences cluster alignment and assembly rate during early-stage assembly only at extremely high shear rates. This suggests that observed improvements in optoelectronic properties at experimentally-accessible shear rates are due to the alignment of large aggregates of hundreds of monomers on time scales in excess of hundreds of nanoseconds. Our work provides new fundamental understanding of the effects of pH and flow to control the morphology and kinetics of early-stage assembly of π-conjugated peptides and lays the groundwork for the rational manipulation of environmental conditions to direct assembly and the attendant emergent optoelectronic properties.

  5. Self-assembly of a chiral lipid gelator controlled by solvent and speed of gelation.

    Science.gov (United States)

    Xue, Pengchong; Lu, Ran; Yang, Xinchun; Zhao, Li; Xu, Defang; Liu, Yan; Zhang, Hanzhuang; Nomoto, Hiroyuki; Takafuji, Makoto; Ihara, Hirotaka

    2009-09-28

    Glutamine derivative 1 with two-photon absorbing units has been synthesized and was found to show gelation ability in some solvents. Its self-assembly in the gel phase could be controlled by the solvent and speed of gelation. For example, in DMSO the organogelator self-assembled into H-aggregates with weak exciton coupling between the aromatic moieties. On the other hand, in DMSO/diphenyl ether (1:9, v/v) the molecules formed 1D aggregates, but with strong exciton coupling due to the small distance between the chromophores. Moreover, the formation of these two kinds of aggregates could be adjusted by the ratio of DMSO to diphenyl ether. In DMSO/toluene, DMSO/butanol, DMSO/butyl acetate, and DMSO/acetic acid systems similar results were observed. Therefore, conversion of the packing model occurs irrespective of the nature of the solvent. Notably, a unique sign inversion in the CD spectra could be realized by controlling the speed of gelation in the DMSO/diphenyl ether (1:9, v/v) system. It was found that a low speed of gelation induces the gelator to adopt a packing model with strong pi-pi interactions between the aromatic units. Moreover, the gels, when excited at 800 nm, emit strong green fluorescence and the quantum chemical calculations suggest that intramolecular charge transfer leads to two-photon absorption of the gelator molecule.

  6. Dynamic Covalent Functionalization as a route to Controlling Self Assembly of Organic Molecules

    Science.gov (United States)

    Pentzer, Emily

    Efforts to optimize the optoelectronic properties of conjugated organic materials are ongoing across many fields of science and engineering. For example, in bulk heterojunction polymer solar cells, researchers seek to optimize absorption of the solar spectrum by the active materials, form interpenetrating domains of p-type and n-type materials to facilitate exciton dissociation, and improve interactions between electrode, charge blocking layers, and active layers to ensure rapid charge transport. One advantage of organic polymers compared to inorganic materials (e.g., silicon), is the low cost and ability process the materials in solution. Moreover, assembly of conjugated organic materials in solution or in the solid state (i.e., films) can be used to optimize both a material's optoelectronic properties and its interface with surfaces and other materials, addressing many of the concerns listed above. Unfortunately, such solution processability requires appendage of insulating alkyl chains to the conjugated frameworks, which don solubility, but are also insulating and thus can hurt device performance. This presentation will report recent results from the Pentzer Lab from Case Western Reserve University on using functional alkyl chains that serve to control self-assembly, control interfaces with other materials, or can be removed by an external stimulus as a route to optimizing the materials for solar cell applications.

  7. Mechanisms of TSC-mediated control of synapse assembly and axon guidance.

    Directory of Open Access Journals (Sweden)

    Sarah Knox

    2007-04-01

    Full Text Available Tuberous sclerosis complex is a dominant genetic disorder produced by mutations in either of two tumor suppressor genes, TSC1 and TSC2; it is characterized by hamartomatous tumors, and is associated with severe neurological and behavioral disturbances. Mutations in TSC1 or TSC2 deregulate a conserved growth control pathway that includes Ras homolog enriched in brain (Rheb and Target of Rapamycin (TOR. To understand the function of this pathway in neural development, we have examined the contributions of multiple components of this pathway in both neuromuscular junction assembly and photoreceptor axon guidance in Drosophila. Expression of Rheb in the motoneuron, but not the muscle of the larval neuromuscular junction produced synaptic overgrowth and enhanced synaptic function, while reductions in Rheb function compromised synapse development. Synapse growth produced by Rheb is insensitive to rapamycin, an inhibitor of Tor complex 1, and requires wishful thinking, a bone morphogenetic protein receptor critical for functional synapse expansion. In the visual system, loss of Tsc1 in the developing retina disrupted axon guidance independently of cellular growth. Inhibiting Tor complex 1 with rapamycin or eliminating the Tor complex 1 effector, S6 kinase (S6k, did not rescue axon guidance abnormalities of Tsc1 mosaics, while reductions in Tor function suppressed those phenotypes. These findings show that Tsc-mediated control of axon guidance and synapse assembly occurs via growth-independent signaling mechanisms, and suggest that Tor complex 2, a regulator of actin organization, is critical in these aspects of neuronal development.

  8. Height control of self-assembled quantum dots by strain engineering during capping

    Energy Technology Data Exchange (ETDEWEB)

    Grossi, D. F., E-mail: d.grossi@tue.nl; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven (Netherlands); Smereka, P. [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Keizer, J. G. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven (Netherlands); Australian Research Council Centre of Excellence for Quantum Computation and Communications, School of Physics, University of New South Wales, Sydney 2052 (Australia); Ulloa, J. M. [Institute for Systems based on Optoelectronics and Microtechnology (ISOM), Universidad Politecnica de Madrid, Avenida Complutense 30, 28040 Madrid (Spain)

    2014-10-06

    Strain engineering during the capping of III-V quantum dots has been explored as a means to control the height of strained self-assembled quantum dots. Results of Kinetic Monte Carlo simulations are confronted with cross-sectional Scanning Tunnel Microscopy (STM) measurements performed on InAs quantum dots grown by molecular beam epitaxy. We studied InAs quantum dots that are capped by In{sub x}Ga{sub (1−x)}As layers of different indium compositions. Both from our realistic 3D kinetic Monte Carlo simulations and the X-STM measurements on real samples, a trend in the height of the capped quantum dot is found as a function of the lattice mismatch between the quantum dot material and the capping layer. Results obtained on additional material combinations show a generic role of the elastic energy in the control of the quantum dot morphology by strain engineering during capping.

  9. Kinetic Control of Microtubule Morphology Obtained by Assembling Gold Nanoparticles on Living Fungal Biotemplates.

    Science.gov (United States)

    Kubo, Andressa M; Gorup, Luiz F; Amaral, Luciana S; Filho, Edson R; Camargo, Emerson R

    2016-10-19

    Self-assembly of nanoparticles on living biotemplate surfaces is a promising route to fabricate nano- or microstructured materials with high efficiency and efficacy. We used filamentous fungi to fabricate microtubules of gold nanoparticles through a novel approach that consists of isolating the hyphal growth from the nanoparticle media. This improved methodology resulted in better morphological control and faster adsorption kinetics, which reduced the time needed to form homogeneous microtubules and allowed for control of microtubule thickness through successive additions of nanoparticles. Differences in the adsorption rates due to modifications in the chemical identity of colloidal gold nanoparticles indicated the influence of secondary metabolites and growth media in the fungi metabolism, which demonstrated the need to choose not only the fungus biotemplate but also the correct medium to obtain microtubules with superior properties.

  10. Controlling active self-assembly through broken particle-shape symmetry.

    Science.gov (United States)

    Wensink, H H; Kantsler, V; Goldstein, R E; Dunkel, J

    2014-01-01

    Many structural properties of conventional passive materials are known to arise from the symmetries of their microscopic constituents. By contrast, it is largely unclear how the interplay between particle shape and self-propulsion controls the meso- and macroscale behavior of active matter. Here we use large-scale simulations of homo- and heterogeneous self-propelled particle systems to identify generic effects of broken particle-shape symmetry on collective motion. We find that even small violations of fore-aft symmetry lead to fundamentally different collective behaviors, which may facilitate demixing of differently shaped species as well as the spontaneous formation of stable microrotors. These results suggest that variation of particle shape yields robust physical mechanisms to control self-assembly of active matter, with possibly profound implications for biology and materials design.

  11. A self-assembled nanoscale robotic arm controlled by electric fields

    Science.gov (United States)

    Kopperger, Enzo; List, Jonathan; Madhira, Sushi; Rothfischer, Florian; Lamb, Don C.; Simmel, Friedrich C.

    2018-01-01

    The use of dynamic, self-assembled DNA nanostructures in the context of nanorobotics requires fast and reliable actuation mechanisms. We therefore created a 55-nanometer–by–55-nanometer DNA-based molecular platform with an integrated robotic arm of length 25 nanometers, which can be extended to more than 400 nanometers and actuated with externally applied electrical fields. Precise, computer-controlled switching of the arm between arbitrary positions on the platform can be achieved within milliseconds, as demonstrated with single-pair Förster resonance energy transfer experiments and fluorescence microscopy. The arm can be used for electrically driven transport of molecules or nanoparticles over tens of nanometers, which is useful for the control of photonic and plasmonic processes. Application of piconewton forces by the robot arm is demonstrated in force-induced DNA duplex melting experiments.

  12. Inorganic Nanowires-Assembled Layered Paper as the Valve for Controlling Water Transportation.

    Science.gov (United States)

    Chen, Fei-Fei; Zhu, Ying-Jie; Xiong, Zhi-Chao; Sun, Tuan-Wei; Shen, Yue-Qin; Yang, Ri-Long

    2017-03-29

    Layered materials with open interlayer channels enable various applications such as tissue engineering, ionic and molecular sieving, and electrochemical devices. However, most reports focus on the two-dimensional nanosheets-assembled layered materials, whose interlayer spacing is limited at the nanometer scale. Herein, we demonstrate that one-dimensional inorganic nanowires are the ideal building blocks for the construction of layered materials with open interlayer channels as well, which has not aroused much attention before. It is found that the relatively long inorganic nanowires are capable of assembling into free-standing layered paper with open interlayer channels during the filtration process. The spacings of interlayer channels between adjacent layers are up to tens of micrometers, which are much larger than those of the two-dimensional nanosheets-assembled layered materials. But the closed interlayer channels are observed when the relatively short inorganic nanowires are used as building blocks. The mechanism based on the relationship between the structural variation and the nanowires used is proposed, including the surface charge amplified effect, surface charge superimposed effect, and pillarlike supporting effect. According to the proposed mechanism, we have successfully fabricated a series of layered paper sheets whose architectures (including interlayer channels of cross section and pores on the surface) show gradient changes. The as-prepared layered paper sheets are employed as the valves for controlling water transportation. Tunable water transportation is achieved by the synergistic effect between in-plane interlayer channels (horizontal transportation) from the open to the closed states, and through-layer pores (vertical transportation) without surface modification or intercalation of any guest species.

  13. Fluid-Mediated Stochastic Self-Assembly at Centimetric and Sub-Millimetric Scales: Design, Modeling, and Control

    Directory of Open Access Journals (Sweden)

    Bahar Haghighat

    2016-08-01

    Full Text Available Stochastic self-assembly provides promising means for building micro-/nano-structures with a variety of properties and functionalities. Numerous studies have been conducted on the control and modeling of the process in engineered self-assembling systems constituted of modules with varied capabilities ranging from completely reactive nano-/micro-particles to intelligent miniaturized robots. Depending on the capabilities of the constituting modules, different approaches have been utilized for controlling and modeling these systems. In the quest of a unifying control and modeling framework and within the broader perspective of investigating how stochastic control strategies can be adapted from the centimeter-scale down to the (sub-millimeter-scale, as well as from mechatronic to MEMS-based technology, this work presents the outcomes of our research on self-assembly during the past few years. As the first step, we leverage an experimental platform to study self-assembly of water-floating passive modules at the centimeter scale. A dedicated computational framework is developed for real-time tracking, modeling and control of the formation of specific structures. Using a similar approach, we then demonstrate controlled self-assembly of microparticles into clusters of a preset dimension in a microfluidic chamber, where the control loop is closed again through real-time tracking customized for a much faster system dynamics. Finally, with the aim of distributing the intelligence and realizing programmable self-assembly, we present a novel experimental system for fluid-mediated programmable stochastic self-assembly of active modules at the centimeter scale. The system is built around the water-floating 3-cm-sized Lily robots specifically designed to be operative in large swarms and allows for exploring the whole range of fully-centralized to fully-distributed control strategies. The outcomes of our research efforts extend the state-of-the-art methodologies

  14. Large-scale self-assembly of uniform submicron silver sulfide material driven by precise pressure control

    Science.gov (United States)

    Qi, Juanjuan; Chen, Ke; Zhang, Shuhao; Yang, Yun; Guo, Lin; Yang, Shihe

    2017-03-01

    The controllable self-assembly of nanosized building blocks into larger specific structures can provide an efficient method of synthesizing novel materials with excellent properties. The self-assembly of nanocrystals by assisted means is becoming an extremely active area of research, because it provides a method of producing large-scale advanced functional materials with potential applications in the areas of energy, electronics, optics, and biologics. In this study, we applied an efficient strategy, namely, the use of ‘pressure control’ to the assembly of silver sulfide (Ag2S) nanospheres with a diameter of approximately 33 nm into large-scale, uniform Ag2S sub-microspheres with a size of about 0.33 μm. More importantly, this strategy realizes the online control of the overall reaction system, including the pressure, reaction time, and temperature, and could also be used to easily fabricate other functional materials on an industrial scale. Moreover, the thermodynamics and kinetics parameters for the thermal decomposition of silver diethyldithiocarbamate (Ag(DDTC)) are also investigated to explore the formation mechanism of the Ag2S nanosized building blocks which can be assembled into uniform sub-micron scale architecture. As a method of producing sub-micron Ag2S particles by means of the pressure-controlled self-assembly of nanoparticles, we foresee this strategy being an efficient and universally applicable option for constructing other new building blocks and assembling novel and large functional micromaterials on an industrial scale.

  15. A numerical and experimental investigation of the thermal control performance of a spaceborne compressor assembly

    Science.gov (United States)

    Oh, Hyun-Ung; Lee, Min-Kyu; Shin, Somin; Hong, Joo-Sung

    2011-09-01

    Spaceborne pulse tube type cryocoolers are widely used for providing cryogenic temperatures for sensitive infrared, gamma-ray and X-ray detectors. Thermal control for the compressor of the cryocooler is one of the important technologies for the cooling performance, mission life time, and jitter stability of the cooler. The thermal design of the compressor assembly proposed in this study is basically composed of a heat pipe, a radiator, and a heater. In the present work, a method for heat pipe implementation is proposed and investigated to ensure the jitter stability of the compressor under the condition that one heat pipe is not working. An optimal design of the radiator that uses ribs for effective use by minimizing the temperature gradient on the radiator and reducing its weight is introduced. The effectiveness of the thermal design of the compressor assembly is demonstrated by on-orbit thermal analysis using the correlated thermal model obtained from the thermal balance test that is performed under a space simulating environment.

  16. Controlled release of astaxanthin from nanoporous silicified-phospholipids assembled boron nitride complex for cosmetic applications

    Science.gov (United States)

    Lee, Hye Sun; Sung, Dae Kyung; Kim, Sung Hyun; Choi, Won Il; Hwang, Ee Tag; Choi, Doo Jin; Chang, Jeong Ho

    2017-12-01

    Nanoporous silicified-phospholipids assembled boron nitride (nSPLs@BN) powder was prepared and demonstrated for use in controlled release of anti-oxidant astaxanthin (AX) as a cosmetic application. The nanoporous silicified phospholipids (nSPLs) were obtained by the silicification with tetraethyl orthosilicate (TEOS) of the hydrophilic region of phospholipid bilayers. This process involved the co-assembly of chemically active phospholipid bilayers within the porous silica matrix. In addition, nSPLs@BN was characterized using several analytical techniques and tested to assess their efficiency as drug delivery systems. We calculated the maximum release amounts as a function of time and various pH. The release rate of AX from the nSPLs@BN for the initial 24 h was 10.7 μmol/(h mg) at pH 7.4. Furthermore, we determined the antioxidant activity (KD) for the released AX with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical and the result was 34.6%.

  17. Controlled self-assembly of quantum dot-block copolymer colloids in multiphase microfluidic reactors.

    Science.gov (United States)

    Wang, Chih-Wei; Oskooei, Ali; Sinton, David; Moffitt, Matthew G

    2010-01-19

    The controlled self-assembly of large compound quantum dot micelles (QDCMs), consisting of constituents of polymer-stabilized quantum dots (QDs) and amphiphilic polystyrene-b-poly(acrylic acid) stabilizing chains, in gas-liquid segmented microfluidic reactors is demonstrated. Self-assembly is initiated by fast mixing of water with the polymer constituents via chaotic advection, as liquid plugs containing reactants move through a sinusoidal mixing channel. The resulting QDCMs are then processed within a postformation channel, where circulating flow patterns develop within the liquid plugs, followed by off-chip quenching and analysis by transmission electron microscopy (TEM). Particle processing via circulating flow is found to involve a combination of particle growth via collision-induced coalescence and shear-induced particle breakup. The final mean QDCM sizes represent kinetic states arising from the competition between these two mechanisms, depending on tunable chemical and flow parameters. A systematic investigation of the experimental variables that influence particle size and polydispersity, including water concentration, flow rate, and the gas-to-liquid flow ratio, is conducted, demonstrating tunability of QDCM sizes in the range of approximately 40-140 nm. The importance of shear-induced particle breakup in the limit of high shear is illustrated by a common minimum particle size, 41 +/- 1 nm, which is achieved for all water contents by increasing the total flow rate to sufficiently high values.

  18. Controlled evaporative self-assembly of confined microfluids: A route to complex ordered structures

    Science.gov (United States)

    Byun, Myunghwan

    The evaporative self-assembly of nonvolatile solutes such as polymers, nanocrystals, and carbon nanotubes has been widely recognized as a non-lithographic means of producing a diverse range of intriguing complex structures. Due to the spatial variation of evaporative flux and possible convection, however, these non-equilibrium dissipative structures (e.g., fingering patterns and polygonal network structures) are often irregularly and stochastically organized. Yet for many applications in microelectronics, data storage devices, and biotechnology, it is highly desirable to achieve surface patterns having a well-controlled spatial arrangement. To date, only a few elegant studies have centered on precise control over the evaporation process to produce ordered structures. In a remarked comparison with conventional lithography techniques, surface patterning by controlled solvent evaporation is simple and cost-effective, offering a lithography- and external field-free means to organize nonvolatile materials into ordered microscopic structures over large surface areas. The ability to engineer an evaporative self-assembly process that yields a wide range of complex, self-organizing structures over large areas offers tremendous potential for applications in electronics, optoelectronics, and bio- or chemical sensors. We developed a facile, robust tool for evaporating polymer, nanoparticle, or DNA solutions in curve-on-flat geometries to create versatile, highly regular microstructures, including hierarchically structured polymer blend rings, conjugated polymer "snake-skins", block copolymer stripes, and punch-hole-like meshes, biomolecular microring arrays, etc. The mechanism of structure formation was elucidated both experimentally and theoretically. Our method further enhances current fabrication approaches to creating highly ordered structures in a simple and cost-effective manner, envisioning the potential to be tailored for use in photonics, optoelectronics, microfluidic

  19. Controlling the self-assembly of protein polymers via heterodimer-forming modules

    NARCIS (Netherlands)

    Domeradzka, Natalia Eliza

    2016-01-01

    Supramolecular assemblies formed by protein polymers are attractive candidates for future biomaterials. Ideally, one would like to be able to define the nanostructure, in which the protein polymers should self-assemble, and then design protein polymer sequences that assemble exactly into such

  20. Colloidal nanocrystals: Synthesis and shape-control, interparticle interactions and self-assembly

    Science.gov (United States)

    Saunders, Aaron Edward

    Control over nanocrystal growth kinetics provides a powerful way of tailoring particle size and shape during synthesis. Investigations into the growth of gold nanocrystals demonstrated how reaction conditions can be adjusted to control the growth rate and produce monodisperse particles. Kinetic control during the synthesis of CdS, CdSe and CdTe nanoparticles allows the shape to be tuned, from rods to spheres, without modifying the reaction chemistry. The growth and optical properties of these shape-anisotropic semiconductor particles were studied, and these methods were extended to produce semiconductor heterostructure nanorods. Solvent-mediated interparticle interactions between nanocrystals dispersed in toluene and in supercritical carbon dioxide were also studied. Nanocrystal dispersions were characterized using small-angle X-ray scattering in order to obtain information about the pair interaction potential. In organic solvents, subtle differences in the concentration-dependent scattering from dispersions allowed second virial coefficients to be measured as a function of nanocrystal size. Interestingly, larger nanocrystals exhibited overall repulsive interactions, while smaller nanocrystals exhibited attractive interactions, which is likely due to differences in ligand coverage among the different sized particles. Nanocrystals coated with fluorinated ligands could be dispersed into supercritical carbon dioxide, and the relatively strong interparticle interactions were measured at different carbon dioxide densities. As expected, the interaction strength increased as the solvent density was lowered, due to a decreased ability of the solvent to solvate the capping ligands. The formation of metastable nanocrystal flocculates was also observed at all system conditions studied. The assembly of nanocrystals into ordered superlattices under equilibrium conditions is strongly influenced by nanocrystal interparticle interactions. The formation of binary superlattices was

  1. Controlled assembly of SNAP-PNA-fluorophore systems on DNA templates to produce fluorescence resonance energy transfer.

    Science.gov (United States)

    Gholami, Zahra; Hanley, Quentin

    2014-10-15

    The SNAP protein is a widely used self-labeling tag that can be used for tracking protein localization and trafficking in living systems. A model system providing controlled alignment of SNAP-tag units can provide a new way to study clustering of fusion proteins. In this work, fluorescent SNAP-PNA conjugates were controllably assembled on DNA frameworks, forming dimers, trimers, and tetramers. Modification of peptide nucleic acid (PNA) with the O(6)-benzyl guanine (BG) group allowed the generation of site-selective covalent links between PNA and the SNAP protein. The modified BG-PNAs were labeled with fluorescent Atto dyes and subsequently chemo-selectively conjugated to SNAP protein. Efficient assembly into dimer and oligomer forms was verified via size exclusion chromatography (SEC), electrophoresis (SDS-PAGE), and fluorescence spectroscopy. DNA-directed assembly of homo- and heterodimers of SNAP-PNA constructs induced homo- and hetero-FRET, respectively. Longer DNA scaffolds controllably aligned similar fluorescent SNAP-PNA constructs into higher oligomers exhibiting homo-FRET. The combined SEC and homo-FRET studies indicated the 1:1 and saturated assemblies of SNAP-PNA-fluorophore:DNA formed preferentially in this system. This suggested a kinetic/stoichiometric model of assembly rather than binomially distributed products. These BG-PNA-fluorophore building blocks allow facile introduction of fluorophores and/or assembly directing moieties onto any protein containing SNAP. Template-directed assembly of PNA-modified SNAP proteins may be used to investigate clustering behavior both with and without fluorescent labels, which may find use in the study of assembly processes in cells.

  2. Neutronic design study of accelerator driven system (ADS) for Jordan subcritical reactor as a neutron source for nuclear research.

    Science.gov (United States)

    Xoubi, Ned

    2018-01-01

    In this paper, a preliminary neutronic design study of an accelerator driven subcritical system for Jordan Subcritical Assembly (JSA) is presented. The conceptual design of coupling the JSA core with proton accelerator and spallation target is investigated, and its feasibility as a neutron source for nuclear research, and possibly for target irradiation and isotope production evaluated. 3D MCNPX model of the JSA reactor, the accelerator beam, and the Pb target was developed, based on actual reactor parameters. MCNPX calculations were carried out to estimate the absolute radial and axial neutron flux in the reactor, and to calculate the multiplication factor K eff and heat generated in the reactor. Numerical results showed an enormous increase in the neutron flux, by seven orders of magnitude, compared to the current JSA core design using Pu-Be source. In this research the results obtained are discussed and compared with those of the JSA, and do confirm the feasibility of utilizing the JSA as a viable nuclear research facility with adequate neutron flux. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Controllable Nanoparticle Assembly and Actuation with Modified Dipole Potentials in Simulation

    Science.gov (United States)

    Dempster, Joshua

    Science at the nanoscale poses several recurring difficulties. How can we control the assembly of objects too small for direct manipulation to be practical? How can we extend that control to in vivo systems so we can make use of nanotechnology in medicine? And how can we recreate the extraordinary capacities of Nature: healing, replication, growth, adaptation, self-regulation? One of the most powerful tools for addressing these challenges is the simple, familiar dipole moment. Since their debut as fuel control devices at NASA in the early sixties, possible applications for dipole suspensions have grown to areas far beyond what their creators envisioned. A multitude of ambitious new medical and mechanical applications make use of dipolar colloids. Dipoles are attractive from a practical standpoint because one can use fields to control not just their orientation and location, but also their mutual interactions. From a physical standpoint, dipoles are compelling as an exceptionally simple form of symmetry-breaking that leads to a variety of complex phenomena. This thesis studies the assembly and control of spherical colloids with a dipolar interaction modified by additional conditions using simulations. Three cases are examined in detail. The first is the case of an electrical dipole moment created by regions of opposite charge density on the surface of a colloid. Here the dipole potential is modified by strong screening. Such a system is interesting as a model for certain proteins in a high-salt solution and suggests possible uses for inverse Janus colloids. The resulting phases have little resemblance to the usual dipole phases and can be controlled with small quantities of homogeneously charged particles. In the second case, superparamagnetic dipoles are linked into chains. Such chains have been realized in a wide variety of experimental schemes. A general theory is developed for the equilibrium shapes of the chains in a precessing field when their endpoints are

  4. Spatial and directional control of self-assembled wrinkle patterns by UV light absorption

    Science.gov (United States)

    Kortz, C.; Oesterschulze, E.

    2017-12-01

    Wrinkle formation on surfaces is a phenomenon that is observed in layered systems with a compressed elastic thin capping layer residing on a viscoelastic film. So far, the properties of the viscoelastic material could only be changed replacing it by another material. Here, we propose to use a photosensitive material whose viscoelastic properties, Young's modulus, and glass transition temperature can easily be adjusted by the absorption of UV light. Employing UV lithography masks during the exposure, we gain additionally spatial and directional control of the self-assembled wrinkle pattern formation that relies on a spinodal decomposition process. Inspired by the results on surface wrinkling and its dependence on the intrinsic stress, we also derive a method to avoid wrinkling locally by tailoring the mechanical stress distribution in the layered system choosing UV masks with convex patterns. This is of particular interest in technical applications where the buckling of surfaces is undesirable.

  5. All-optically controlled light valve assembled by photorefractive crystal and PDLC hybrid structure

    Science.gov (United States)

    Marinova, Vera; Liu, Ren Chung; Chen, Ming S.; Lin, Shiuan Huei; Lin, Yi Hsin; Hsu, Ken Yuh

    2015-05-01

    A light-valve device, assembled by Ru-doped Bi12SiO20 (BSO) photoconductive substrate and polymer dispersed liquid crystal layer is proposed, in which all the processes are controlled by the near infrared light. Laser beam illumination (Gaussian shape) on BSO:Ru crystal caused charge carriers generation, which migrate and form an inhomogeneous distribution and subsequent space charge field. This surface-localized electromagnetic field penetrates into the PDLC layer and modulate the orientation of the liquid crystals, that caused reverse of the device initial opaque state to the highly transparent one. The proposed structure is simple and easy to fabricate, without requirements of ITO contacts and alignment layers and opens further possibilities for near-infrared applications.

  6. Constructing Asymmetric Polyion Complex Vesicles via Template Assembling Strategy: Formulation Control and Tunable Permeability

    Directory of Open Access Journals (Sweden)

    Junbo Li

    2017-11-01

    Full Text Available A strategy for constructing polyion complex vesicles (PICsomes with asymmetric structure is described. Poly(methylacrylic acid-block-poly(N-isopropylacrylamide modified gold nanoparticles (PMAA-b-PNIPAm-@-Au NPs were prepared and then assembled with poly(ethylene glycol-block-poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine] (PEG-b-PMMPImB via polyion complex of PMMA and PMMPImB. After removing the Au NPs template, asymmetric PICsomes composed of a PNIPAm inner-shell, PIC wall, and PEG outer-corona were obtained. These PICsomes have low protein absorption and thermally tunable permeability, provided by the PEG outer-corona and the PNIPAm inner-shell, respectively. Moreover, PICsome size can be tailored by using templates of predetermined sizes. This novel strategy for constructing asymmetric PICsomes with well-defined properties and controllable size is valuable for applications such as drug delivery, catalysis and monitoring of chemical reactions, and biomimetics.

  7. Temporal control of nuclear envelope assembly by phosphorylation of lamin B receptor.

    Science.gov (United States)

    Tseng, Li-Chuan; Chen, Rey-Huei

    2011-09-01

    The nuclear envelope of metazoans disassembles during mitosis and reforms in late anaphase after sister chromatids have well separated. The coordination of these mitotic events is important for genome stability, yet the temporal control of nuclear envelope reassembly is unknown. Although the steps of nuclear formation have been extensively studied in vitro using the reconstitution system from egg extracts, the temporal control can only be studied in vivo. Here, we use time-lapse microscopy to investigate this process in living HeLa cells. We demonstrate that Cdk1 activity prevents premature nuclear envelope assembly and that phosphorylation of the inner nuclear membrane protein lamin B receptor (LBR) by Cdk1 contributes to the temporal control. We further identify a region in the nucleoplasmic domain of LBR that inhibits premature chromatin binding of the protein. We propose that this inhibitory effect is partly mediated by Cdk1 phosphorylation. Furthermore, we show that the reduced chromatin-binding ability of LBR together with Aurora B activity contributes to nuclear envelope breakdown. Our studies reveal for the first time a mechanism that controls the timing of nuclear envelope reassembly through modification of an integral nuclear membrane protein.

  8. Dimerization control in the self-assembly behavior of copillar[5]arenes bearing ω-hydroxyalkoxy groups.

    Science.gov (United States)

    Liu, Luzhi; Wang, Lingyun; Liu, Changchun; Fu, Zhiyong; Meier, Herbert; Cao, Derong

    2012-10-19

    Two novel copillar[5]arenes bearing ω-hydroxyalkoxy groups are synthesized and their self-assembly properties are studied by (1)H NMR spectroscopy, specific viscosity, and X-ray measurements. The copillar[5]arene 2b bearing a 6-hydroxyhexyloxy group exhibits a reversible self-assembly behavior, leading to the formation of the self-inclusion monomer and hugging dimers. The reversible self-assembly behavior can be controlled by tuning solvent, temperature, guest, and H-bond interaction. However, the copillar[5]arene 2a bearing a short 4-hydroxybutyloxy group does not show such a self-assembly behavior to the formation of the self-inclusion monomer and hugging dimers.

  9. Controlling self-assembly and ordering of block polymer nanostructures in thin films

    Science.gov (United States)

    Luo, Ming

    Block polymers have garnered significant attention in the past few decades due to their ability to self-assemble into a boundless array of structures such as spheres, cylinders, gyroid, and lamellae. The sizes of the periodical structures typically are 5 - 100 nm, making them ideal for emerging nanotechnologies, such as nanolithography, nanotemplating, nanoporous membranes, and photonics devices. Many of these applications require thin film geometries, in which the block polymers form well-ordered nanostructures and precisely controlled domain orientations. Understanding the factors that affect thin film phase behavior and being able to control the nanostructures, domain orientation, and domain ordering in thin film is essential to realizing the full potential of these unique materials. In this dissertation, I describe significant efforts to manipulate the block polymer thin film structures, direct the nanostructure ordering, and understand the connection between the macromolecular molecular structures and the block polymer properties. First, substrate surface modification with chlorosilane was employed to manipulate the nanostructure of poly(styrene- b-isoprene-b-styrene) (SIS) thin films. A morphological transformation from parallel cylinders to hexagonally perforated lamellae (HPL) was identified, in a high-throughput fashion, using gradient methods. The gradient methods are highly adaptable for the possible universal manipulation of thin film nanostructures. Second, rastering solvent vapor annealing - soft shear method was developed and demonstrated as a simple, yet highly effective method to achieve macroscopic alignment of SIS cylinders. This method substantially improves on previous approaches by using simple instrumentation to unlock an array of alignment patterns with a variety of self-assembling polymers and provides feasibility and flexibility for practical industrial production. Next, the interfacial mixing characteristics of tapered block polymer were

  10. The Model of Temperature Dynamics of Pulsed Fuel Assembly

    CERN Document Server

    Bondarchenko, E A; Popov, A K

    2002-01-01

    Heat exchange process differential equations are considered for a subcritical fuel assembly with an injector. The equations are obtained by means of the use of the Hermit polynomial. The model is created for modelling of temperature transitional processes. The parameters and dynamics are estimated for hypothetical fuel assembly consisting of real mountings: the powerful proton accelerator and the reactor IBR-2 core at its subcritica l state.

  11. The safe, economical operation of a slightly subcritical reactor and transmutor with a small proton accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi

    1994-04-01

    This report describes methods in which an accelerator can be used to increase the safety and neutron economy of a power reactor and transmutor of long-lived radioactive wastes, such as minor actinides and fission products, by providing neutrons for its subcritical operation. Instead of the rather large subcriticality of k=0.9--0.95 which we originally proposed for such a transmutor, we propose to use a slightly subcritical reactor, such as k=0.99, which will avoid many of the technical difficulties that are associated with large subcriticality, such as localized power peaking, radiation damage due to the injection of medium-energy protons, the high current accelerator, and the requirement for a long beam-expansion section. We analyzed the power drop that occurred in Phoenix reactor, and show that the operating this reactor in subcritical condition improves its safety.

  12. A multiple objective test assembly approach for exposure control problems in Computerized Adaptive Testing

    Directory of Open Access Journals (Sweden)

    Theo J.H.M. Eggen

    2010-01-01

    Full Text Available Overexposure and underexposure of items in the bank are serious problems in operational computerized adaptive testing (CAT systems. These exposure problems might result in item compromise, or point at a waste of investments. The exposure control problem can be viewed as a test assembly problem with multiple objectives. Information in the test has to be maximized, item compromise has to be minimized, and pool usage has to be optimized. In this paper, a multiple objectives method is developed to deal with both types of exposure problems. In this method, exposure control parameters based on observed exposure rates are implemented as weights for the information in the item selection procedure. The method does not need time consuming simulation studies, and it can be implemented conditional on ability level. The method is compared with Sympson Hetter method for exposure control, with the Progressive method and with alphastratified testing. The results show that the method is successful in dealing with both kinds of exposure problems.

  13. Enzyme-Controlled Intracellular Self-Assembly of 18F Nanoparticles for Enhanced MicroPET Imaging of Tumor

    OpenAIRE

    Liu, Yaling; Miao, Qingqing; Zou, Pei; Liu, Longfei; Wang, Xiaojing; An, Linna; Zhang, Xiaoliu; Qian, Xiangping; Luo, Shineng; Liang, Gaolin

    2015-01-01

    Herein, we report the development of a new ?smart? radioactive probe (i.e., 1) which can undergo furin-controlled condensation and self-assembly of radioactive nanoparticles (i.e., 1-NPs) in tumor cells and its application for enhanced microPET imaging of tumors in nude mice co-injected with its cold analog (i.e., 1-Cold). Furin-controlled condensation of 1-Cold and self-assembly of its nanoparticles (i.e., 1-Cold-NPs) in vitro were validated and characterized with HPLC, mass spectra, SEM, an...

  14. Subcritical and supercritical water oxidation of CELSS model wastes

    Science.gov (United States)

    Takahashi, Y.; Wydeven, T.; Koo, C.

    1989-01-01

    A mixture of ammonium hydroxide with acetic acid and a slurry of human feces, urine, and wipes were used as CELSS model wastes to be wet-oxidized at temperatures from 250 to 500 C, i.e. below and above the critical point of water (374 C and 218 kg/sq cm or 21.4 MPa). The effects of oxidation temperature ( 250-500 C) and residence time (0-120 mn) on carbon and nitrogen and on metal corrosion from the reactor material were studied. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 C, above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. A substantial amount of nitrogen remained in solution in the form of ammonia at temperatures ranging from 350 to 450 C suggesting that, around 400 C, organic carbon is completely oxidized and most of the nitrogen is retained in solution. The Hastelloy C-276 alloy reactor corroded during subcritical and supercritical water oxidation.

  15. Hydrolysis of sweet blue lupin hull using subcritical water technology.

    Science.gov (United States)

    Ciftci, Deniz; Saldaña, Marleny D A

    2015-10-01

    Hydrolysis of sweet blue lupin hulls was conducted in this study using subcritical water technology. Effects of process parameters, such as pressure (50-200 bar), temperature (160-220°C), flow rate (2-10 mL/min), and pH (2-12), were studied to optimize maximum hemicellulose sugars recovery in the extracts. Extracts were analyzed for total hemicellulose sugars, phenolics and organic carbon contents and solid residues left after treatments were also characterized. Temperature, flow rate, and pH had a significant effect on hemicellulose sugar removal; however, the effect of pressure was not significant. The highest yield of hemicellulose sugars in the extracts (85.5%) was found at 180°C, 50 bar, 5 mL/min and pH 6.2. The thermal stability of the solid residue obtained at optimum conditions improved after treatment and the crystallinity index increased from 11.5% to 58.6%. The results suggest that subcritical water treatment is a promising technology for hemicellulose sugars removal from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Subcritical water extractor for Mars analog soil analysis.

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank J; Patrick, Steven B; Yung, Pun To

    2008-06-01

    Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).

  17. Sialic acid residues on astrocytes regulate neuritogenesis by controlling the assembly of laminin matrices.

    Science.gov (United States)

    Freire, Elisabete; Gomes, Flávia C A; Jotha-Mattos, Tatiana; Neto, Vivaldo Moura; Silva Filho, Fernando C; Coelho-Sampaio, Tatiana

    2004-08-15

    In the developing nervous system migrating neurons and growing axons are guided by diffusible and/or substrate-bound cues, such as extracellular matrix-associated laminin. In a previous work we demonstrated that laminin molecules could self-assemble in two different manners, giving rise to matrices that could favor either neuritogenesis or proliferation of cortical precursor cells. We investigated whether the ability of astrocytes to promote neuritogenesis of co-cultivated neurons was modulated by the assembling mode of the laminin matrix secreted by them. We compared the morphologies and neuritogenic potentials of laminin deposited by in vitro-differentiated astrocytes obtained from embryonic or neonatal rat brain cortices. We showed that, while permissive astrocytes derived from embryonic brain produced a flat laminin matrix that remained associated to the cell surface, astrocytes derived from newborn brain secreted a laminin matrix resembling a fibrillar web that protruded from the cell plane. The average neurite lengths obtained for E16 neurons cultured on each astrocyte layer were 198+/-22 and 123+/-13 microm, respectively. Analyses of surface-associated electrostatic potentials revealed that embryonic astrocytes presented a pI of -2.8, while in newborn cells this value was -3.8. Removal of the sialic acid groups on the embryonic monolayer by neuraminidase treatment led to the immediate release of matrix-associated laminin. Interestingly, laminin reassembled 1 hour after neuraminidase removal converted to the features of the newborn matrix. Alternatively, treatment of astrocytes with the cholesterol-solubilizing detergent methyl-beta-cyclodextrin also resulted in release of the extracellular laminin. To test the hypothesis that sialic-acid-containing lipids localized at cholesterol-rich membrane domains could affect the process of laminin assembly, we devised a cell-free assay where laminin polymerization was carried out over artificial lipid films. Films of

  18. Self-assembly of designed precursors: A route to crystallographically aligned new materials with controlled nanoarchitecture

    Energy Technology Data Exchange (ETDEWEB)

    Westover, Richard, E-mail: rwestove@uoregon.edu; Atkins, Ryan A.; Falmbigl, Matthias; Ditto, Jeffrey J.; Johnson, David C.

    2016-04-15

    Modulated elemental reactants is a method by which new and complex intergrowth compounds can be synthesized by the self-assembly of designed precursors prepared by physical vapor deposition. Careful calibration of the composition and thickness of the precursors ensures the formation of the desired product by precise control of local composition and diffusion lengths. Superstructures of increasing complexity can be realized using binary and ternary systems as starting points. The synthesis of systems based on three different binary compounds, either alloyed together or separated into distinct layers, expands the number of possible superstructures that can be formed using this technique, but provides analytical challenges. The synthesis of [(SnSe){sub 1.15}]{sub 1}([Ta{sub x}V{sub 1−x}]Se{sub 2}){sub 1}[(SnSe){sub 1.15}]{sub 1}([V{sub y}Ta{sub 1−y}]Se{sub 2}){sub 1} compound is used to illustrate the preparation of precursors and the challenges in both measuring and limiting the interdiffusion of layers during self-assembly. Systematic changes in the electrical properties of (SnSe){sub 1+δ}(Ta{sub x}V{sub 1−x})Se{sub 2} alloys are observed as x is varied. The electrical resistivity of [(SnSe){sub 1.15}]{sub 1}([Ta{sub x}V{sub 1−x}]Se{sub 2}){sub 1}[(SnSe){sub 1.15}]{sub 1}([V{sub y}Ta{sub 1−y}]Se{sub 2}){sub 1} can be modeled as the two constituent layers in parallel.

  19. Mechatronic Development and Vision Feedback Control of a Nanorobotics Manipulation System inside SEM for Nanodevice Assembly

    Directory of Open Access Journals (Sweden)

    Zhan Yang

    2016-09-01

    Full Text Available Carbon nanotubes (CNT have been developed in recent decades for nanodevices such as nanoradios, nanogenerators, carbon nanotube field effect transistors (CNTFETs and so on, indicating that the application of CNTs for nanoscale electronics may play a key role in the development of nanotechnology. Nanorobotics manipulation systems are a promising method for nanodevice construction and assembly. For the purpose of constructing three-dimensional CNTFETs, a nanorobotics manipulation system with 16 DOFs was developed for nanomanipulation of nanometer-scale objects inside the specimen chamber of a scanning electron microscope (SEM. Nanorobotics manipulators are assembled into four units with four DOFs (X-Y-Z-θ individually. The rotational one is actuated by a picomotor. That means a manipulator has four DOFs including three linear motions in the X, Y, Z directions and a 360-degree rotational one (X-Y-Z-θ stage, θ is along the direction rotating with X or Y axis. Manipulators are actuated by picomotors with better than 30 nm linear resolution and <1 micro-rad rotary resolution. Four vertically installed AFM cantilevers (the axis of the cantilever tip is vertical to the axis of electronic beam of SEM served as the end-effectors to facilitate the real-time observation of the operations. A series of kinematic derivations of these four manipulators based on the Denavit-Hartenberg (D-H notation were established. The common working space of the end-effectors is 2.78 mm by 4.39 mm by 6 mm. The manipulation strategy and vision feedback control for multi-manipulators operating inside the SEM chamber were been discussed. Finally, application of the designed nanorobotics manipulation system by successfully testing of the pickup-and-place manipulation of an individual CNT onto four probes was described. The experimental results have shown that carbon nanotubes can be successfully picked up with this nanorobotics manipulation system.

  20. Kinetic and Thermodynamic Control in Porphyrin and Phthalocyanine Self-Assembled Monolayers.

    Science.gov (United States)

    Hipps, K W; Mazur, Ursula

    2017-09-20

    Porphyrins and phthalocyanines are ubiquitous in modern science and technology. Their stability, redox properties, and photoresponse make them candidates for numerous applications. Many of these applications rely on thin films, and these are critically dependent on the first monolayer. In this article, we focus on noncovalently bound self-assembled monolayers of porphyrins and phthalocyanines at the solution-solid interface with special emphasis on the kinetic and thermodynamic processes that define the films and their reaction chemistry. We first discuss the difference between film-formation kinetics and desorption kinetics from fully formed films. We then present evidence that many of these monolayers are controlled by adsorption kinetics and are not in thermodynamic equilibrium. Measurement of the solution-solid interface desorption energy by scanning tunneling microscopy is discussed, and data is presented for cobalt, nickel, and free base octaethylporphyrin. The activation energy for the desorption of these compounds into phenyloctane is about half of the computed desorption energy in vacuum, and this is discussed in terms of the role of the solvent. Preexponential factors are very low compared to desorption into vacuum, and this is attributed to a reduction in the entropy of activation due to the participation of solvent in the transition state. An example of the use of relative desorption kinetics to create a new binary surface structure is given. It is suggested that this is a synthesis route that may have been missed because of the large difference in solution concentrations required to drive binary film formation. Attention then turns to the axial reaction chemistry of metalloporphyrins and metallophthalocyanines supported on conducting surfaces. We show several examples of chemistry unique to the supported complexes: cases where the metal binds ligands more readily and cases where the substrate induces ligand loss. Understanding this new axial

  1. Mechatronic Development and Vision Feedback Control of a Nanorobotics Manipulation System inside SEM for Nanodevice Assembly.

    Science.gov (United States)

    Yang, Zhan; Wang, Yaqiong; Yang, Bin; Li, Guanghui; Chen, Tao; Nakajima, Masahiro; Sun, Lining; Fukuda, Toshio

    2016-09-14

    Carbon nanotubes (CNT) have been developed in recent decades for nanodevices such as nanoradios, nanogenerators, carbon nanotube field effect transistors (CNTFETs) and so on, indicating that the application of CNTs for nanoscale electronics may play a key role in the development of nanotechnology. Nanorobotics manipulation systems are a promising method for nanodevice construction and assembly. For the purpose of constructing three-dimensional CNTFETs, a nanorobotics manipulation system with 16 DOFs was developed for nanomanipulation of nanometer-scale objects inside the specimen chamber of a scanning electron microscope (SEM). Nanorobotics manipulators are assembled into four units with four DOFs (X-Y-Z-θ) individually. The rotational one is actuated by a picomotor. That means a manipulator has four DOFs including three linear motions in the X, Y, Z directions and a 360-degree rotational one (X-Y-Z-θ stage, θ is along the direction rotating with X or Y axis). Manipulators are actuated by picomotors with better than 30 nm linear resolution and <1 micro-rad rotary resolution. Four vertically installed AFM cantilevers (the axis of the cantilever tip is vertical to the axis of electronic beam of SEM) served as the end-effectors to facilitate the real-time observation of the operations. A series of kinematic derivations of these four manipulators based on the Denavit-Hartenberg (D-H) notation were established. The common working space of the end-effectors is 2.78 mm by 4.39 mm by 6 mm. The manipulation strategy and vision feedback control for multi-manipulators operating inside the SEM chamber were been discussed. Finally, application of the designed nanorobotics manipulation system by successfully testing of the pickup-and-place manipulation of an individual CNT onto four probes was described. The experimental results have shown that carbon nanotubes can be successfully picked up with this nanorobotics manipulation system.

  2. Damage Control Plan for International Space Station Recharge Tank Assembly Composite Overwrapped Pressure Vessel

    Science.gov (United States)

    Cook, Anthony J.

    2011-01-01

    As NASA has retired the Space Shuttle Program, a new method of transporting compressed gaseous nitrogen and oxygen needed to be created for delivery of these crucial life support resources to the International Space Station (ISS). One of the methods selected by NASA includes the use of highly pressurized, unprotected Recharge Tank Assemblies (RTAs) utilizing Composite Overwrapped Pressure Vessels (COPVs). A COPV consists of a thin liner wrapped with a fiber composite and resin or epoxy. It is typically lighter weight than an all metal pressure vessel of similar volume and therefore provides a higher-efficiency means for gas storage. However COPVs are known to be susceptible to damage resulting from handling, tool drop impacts, or impacts from other objects. As a result, a comprehensive Damage Control Plan has been established to mitigate damage to the RTA COPV throughout its life cycle. The DCP is intended to evaluate and mitigate defined threats during manufacturing, shipping and handling, test, assembly level integration, shipment while pressurized, launch vehicle integration and mission operations by defining credible threats and methods for preventing potential damage while still maintaining the primary goal of resupplying ISS gas resources. A comprehensive threat assessment is performed to identify all threats posed to the COPV during the different phases of its lifecycle. The threat assessment is then used as the basis for creating a series of general inspection, surveillance and reporting requirements which apply across all phases of the COPV's life, targeted requirements only applicable to specific work phases and a series of training courses for both ground personnel and crew aboard the ISS. A particularly important area of emphasis deals with creating DCP requirements for a highly pressurized, large and unprotected RTA COPV for use during Inter Vehicular Activities (IVA) operations in the micro gravity environment while supplying pressurized gas to the

  3. Production of medical radioactive isotopes using KIPT electron driven subcritical facility.

    Science.gov (United States)

    Talamo, Alberto; Gohar, Yousry

    2008-05-01

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine in collaboration with Argonne National Laboratory (ANL) has a plan to construct an electron accelerator driven subcritical assembly. One of the facility objectives is the production of medical radioactive isotopes. This paper presents the ANL collaborative work performed for characterizing the facility performance for producing medical radioactive isotopes. First, a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Then, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes have been considered and all transmutation channels are used including (n, gamma), (n, 2n), (n, p), and (gamma, n). In the second part, the parent isotopes with high reaction rate were explicitly modeled in the calculations. Four irradiation locations were considered in the analyses to study the medical isotope production rate. The results show the self-shielding effect not only reduces the specific activity but it also changes the irradiation location that maximizes the specific activity. The axial and radial distributions of the parent capture rates have been examined to define the irradiation sample size of each parent isotope.

  4. Enzymatic tailoring for precise control of plasmonic resonance absorbance of gold nanoparticle assemblies.

    Science.gov (United States)

    Kim, Joong Hyun; Kim, Jung-Won; Chung, Bong Hyun

    2011-08-15

    We report an enzymatic method to control the plasmon resonance absorbance of gold nanoparticle (AuNP) arrays assembled on hyaluronic acids. While multiple electrostatic interactions between cysteamine on the AuNPs and the carboxylic acid residues in the whole intact hyaluronic acid induced the formation of large aggregates, precise control of the plasmon absorbance was possible by tailoring the size of the bio-polymeric templates with hyaluronidase, almost over the entire range of the resonant coupling wavelengths. It was possible to precisely tune the position of the second plasmon absorbance by manipulating the amount of the template and the enzymatic hydrolysis time. Finally, we were able to produce a chain-like array of AuNPs, which was nearly one dimensional, with a maximum shift of up to 189 nm in the plasmon absorbance at the optimal hydrolysis time of the templates. This enzymatic method can be used as a useful tool to tailor the plasmonic properties of the nanostructures required for specific applications. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Controlled growth of hexagonal gold nanostructures during thermally induced self-assembling on Ge(001) surface

    Science.gov (United States)

    Jany, B. R.; Gauquelin, N.; Willhammar, T.; Nikiel, M.; van den Bos, K. H. W.; Janas, A.; Szajna, K.; Verbeeck, J.; van Aert, S.; van Tendeloo, G.; Krok, F.

    2017-02-01

    Nano-sized gold has become an important material in various fields of science and technology, where control over the size and crystallography is desired to tailor the functionality. Gold crystallizes in the face-centered cubic (fcc) phase, and its hexagonal closed packed (hcp) structure is a very unusual and rare phase. Stable Au hcp phase has been reported to form in nanoparticles at the tips of some Ge nanowires. It has also recently been synthesized in the form of thin graphene-supported sheets which are unstable under electron beam irradiation. Here, we show that stable hcp Au 3D nanostructures with well-defined crystallographic orientation and size can be systematically created in a process of thermally induced self-assembly of thin Au layer on Ge(001) monocrystal. The Au hcp crystallite is present in each Au nanostructure and has been characterized by different electron microscopy techniques. We report that a careful heat treatment above the eutectic melting temperature and a controlled cooling is required to form the hcp phase of Au on a Ge single crystal. This new method gives scientific prospects to obtain stable Au hcp phase for future applications in a rather simple manner as well as redefine the phase diagram of Gold with Germanium.

  6. Self-assembly of diphenylalanine peptide with controlled polarization for power generation

    Science.gov (United States)

    Nguyen, Vu; Zhu, Ren; Jenkins, Kory; Yang, Rusen

    2016-11-01

    Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V-1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm-2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

  7. The controllable assembly of nanorods, nanowires and microwires of a perylenediimide molecule with photoswitching property

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ying, E-mail: yingma@imr.ac.cn [School of Materials Science and Engineering, Shenyang Jianzhu University, Shenyang 110168 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science (China); An, Boxing; Wang, Meng; Shi, Fangxiao; Wang, Qing; Gu, Yaxin; Niu, Wanyang; Fan, Zhaorong [School of Materials Science and Engineering, Shenyang Jianzhu University, Shenyang 110168 (China); Shang, Yanli [College of Chemistry and Environmental Science, Hebei University, Baoding 071002 (China); Wang, Dan; Zhao, Cong [School of Materials Science and Engineering, Shenyang Jianzhu University, Shenyang 110168 (China)

    2015-07-15

    By using an electron donor–acceptor molecule that consists of a perylenediimide (PDI) core bonded with two ferrocene (Fc) units, well-defined nanorods, nanowires and microwires of PDI-Fc were formed through simply adjusting the initial concentration of PDI-Fc in dichloromethane or CH{sub 2}Cl{sub 2}. Moreover, the two-ended devices based on individual microwire were fabricated. Highly reproducible and sensitive photo response characteristics were demonstrated in the microwire through controlling the white light on and off with different light intensities. The assembly strategy via complementary donors and acceptors is of significance for constructing photoconductive systems and developing novel functional devices. - Graphical abstract: The two-ended devices based on individual microwire were fabricated. Highly reproducible and sensitive photo response characteristics were observed by controlling the white light on and off with different light intensities. - Highlights: • An electron donor–acceptor molecule (PDI-Fc) was synthesized. • Well-defined nanorods, nanowires and microwires of PDI-Fc were formed. • The two-ended devices based on individual microwire were fabricated. • Highly reproducible and sensitive photo response characteristics were observed.

  8. Design parameters for voltage-controllable directed assembly of single nanoparticles

    NARCIS (Netherlands)

    Porter, Benjamin F.; Abelmann, Leon; Bhaskaran, Harish

    2013-01-01

    Techniques to reliably pick-and-place single nanoparticles into functional assemblies are required to incorporate exotic nanoparticles into standard electronic circuits. In this paper we explore the use of electric fields to drive and direct the assembly process, which has the advantage of being

  9. Micro-mold design controls the 3D morphological evolution of self-assembling multicellular microtissues.

    Science.gov (United States)

    Svoronos, Alexander A; Tejavibulya, Nalin; Schell, Jacquelyn Y; Shenoy, Vivek B; Morgan, Jeffrey R

    2014-04-01

    When seeded into nonadhesive micro-molds, cells self-assemble three-dimensional (3D) multicellular microtissues via the action of cytoskeletal-mediated contraction and cell-cell adhesion. The size and shape of the tissue is a function of the cell type and the size, shape, and obstacles of the micro-mold. In this article, we used human fibroblasts to investigate some of the elements of mold design and how they can be used to guide the morphological changes that occur as a 3D tissue self-organizes. In a loop-ended dogbone mold with two nonadhesive posts, fibroblasts formed a self-constrained tissue whose tension induced morphological changes that ultimately caused the tissue to thin and rupture. Increasing the width of the dogbone's connecting rod increased the stability, whereas increasing its length decreased the stability. Mapping the rupture points showed that the balance of cell volume between the toroid and connecting rod regions of the dogbone tissue controlled the point of rupture. When cells were treated with transforming growth factor-β1, dogbones ruptured sooner due to increased cell contraction. In mold designs to form tissues with more complex shapes such as three interconnected toroids or a honeycomb, obstacle design controlled tension and tissue morphology. When the vertical posts were changed to cones, they became tension modulators that dictated when and where tension was released in a large self-organizing tissue. By understanding how elements of mold design control morphology, we can produce better models to study organogenesis, examine 3D cell mechanics, and fabricate building parts for tissue engineering.

  10. Control over Structure and Function of Peptide Amphiphile Supramolecular Assemblies through Molecular Design and Energy Landscapes

    Science.gov (United States)

    Tantakitti, Faifan

    a controlled local release of the soluble growth factor bone morphogenetic protein 4 (BMP-4) was realized from the particle's core composed of cross-linked alginate. The alginate-core and PA-shell microparticles were found to allow independent tuning of the bioactivity of a PA and a release of the growth factor for specific signaling to cells. Using microcarriers which encapsulated BMP-4 and coated with RGDS PA nanofibers, it was shown that a control over spatial distribution, proliferation, and osteogenic differentiation of premyoblastic cells on the surface of microcarriers can be effectively achieved. Finally, in drastic contrast to the traditional approach to material development based on altering molecular structure, chapter 4 presents the energy landscapes in which supramolecular assemblies of unique architecture exist in different thermodynamic wells. Experimental results and calculations revealed that the energy landscapes are rooted in competing interactions between PA monomers, namely beta-sheet hydrogen bonds and repulsion among charged groups. Switching off or on the repulsive electrostatic interactions by changing the ionic strength promoted or suppressed the dominant ?-sheet hydrogen bonding interactions respectively. However, the dominant forces can prevail if the assemblies are above a certain size and thereby can exist in a kinetically trapped state. Preparative pathways involving dilution, annealing, and addition of salt were investigated in which the structures belonging to different energy states could be accessed and demonstrated that these energy landscapes involving competitive interactions was applicable not only to PA systems but also to a non-peptide supramolecular system based on pi-orbital overlaps as the dominant attraction among molecules and electrostatic repulsion. In chapter 5, structure and biological function relationships of long or short PA nanofibers are reported, and such fibers were prepared from identical monomers based on

  11. Thorium as a Fuel for Accelerator Driven Subcritical Electronuclear Systems

    CERN Document Server

    Barashenkov, V S; Singh, V

    2000-01-01

    Neutron yield and energy production in a very large, practically infinite, uranium and thorium target-blocks irradiated by protons with energies in the range 0.1-2 GeV are studied by Monte Carlo method. Though the comparison of uranium and thorium targets shows that the neutron yield in the latter is 30-40 % less and the energy gain is approximatelly two times smaller, accelerator Driven subcritical Systems (ADS) with thorium fuel are very perspective at the bombarding energies higher than several hundreds MeV. An admixture of fissile elements U^{233}, U^{235}, Pu^{239} in the set-up gives larger neutron multiplication which in turn shows better energy amplification. It is argued that due to the practically complete burning of the fuel in such set-up there is no need of technology of conversion of the exhaust fuel.

  12. Gravity-driven soap film dynamics in subcritical regimes

    Science.gov (United States)

    Auliel, M. I.; Castro, F.; Sosa, R.; Artana, G.

    2015-10-01

    We undertake the analysis of soap-film dynamics with the classical approach of asymptotic expansions. We focus our analysis in vertical soap film tunnels operating in subcritical regimes with elastic Mach numbers Me=O(10-1) . Considering the associated set of nondimensional numbers that characterize this flow, we show that the flow behaves as a two-dimensional (2D) divergence free flow with variable mass density. When the soap film dynamics agrees with that of a 2D and almost constant mass density flow, the regions where the second invariant of the velocity gradient is non-null correspond to regions where the rate of change of film thickness is non-negligible.

  13. Control of Directed Self-Assembly in Block Polymers by Polymeric Topcoats

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Hernández, Abelardo; Suh, Hyo Seon; Nealey, Paul F.; de Pablo, Juan J.

    2014-05-27

    The morphology of a block copolymer thin film is particularly sensitive to its boundary conditions. Lithographic applications of block polymers in the microelectronics and memory device industries require formation of morphologies with perpendicularly oriented domains. Current fabrication targets envisage the creation of dense arrays of structures with domain sizes in the sub-10 nanometer regime. Such length scales can be reached by resorting to block polymers with highly incompatible blocks (and a large Flory-Huggings parameter, x). High-x values, however, generally lead to large differences in the surface energies of the corresponding blocks, thereby interfering with formation of the sought after perpendicularly oriented domains. In this work, a theoretically informed coarse grain model is used to introduce a topcoat strategy that enables control of the orientation of block copolymer domains in highly incompatible block polymer materials. A systematic study of a wide range of polymeric material combinations is presented, and the conditions leading to optimal assembly of perpendicular morphologies are clearly identified. We consider the effect of molecular weight, block polymer film thickness and architecture, and degree of incompatibility. Our results are summarized in the form of generic phase diagrams that should serve as a guide for experimental deployment of the top-coat strategy put forth in this work.

  14. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae, E-mail: nicolae.leopold@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics (Romania)

    2014-12-15

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl{sub 4} by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of ∼20 and ∼120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4–8 and 10–30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV–Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  15. Photoresponsive ionic liquid crystals assembled via halogen bond: en route towards light-controllable ion transporters.

    Science.gov (United States)

    Saccone, Marco; Palacio, Francisco Fernandez; Cavallo, Gabriella; Dichiarante, Valentina; Virkki, Matti; Terraneo, Giancarlo; Priimagi, Arri; Metrangolo, Pierangelo

    2017-10-13

    We demonstrate that halogen bonding (XB) can offer a novel approach for the construction of photoresponsive ionic liquid crystals. In particular, we assembled two new supramolecular complexes based on 1-ethyl-3-methylimidazolium iodides and azobenzene derivatives containing an iodotetrafluoro-benzene ring as XB donor, where the iodide anion acted as an XB acceptor. DSC and X-ray diffraction analyses revealed that the preferred stoichiometry between the XB donors and acceptors is 2 : 1, and that the iodide anions act as bidentate XB-acceptors, binding two azobenzene derivatives. Due to the high directionality of the XB, calamitic superanions are obtained, while the segregation occurring between the charged and uncharged parts of the molecules gives rise to a layered structure in the crystal lattice. Despite the fact that the starting materials are non-mesomorphic, the halogen-bonded supramolecular complexes exhibited monotropic lamellar liquid-crystalline phases over broad temperature ranges, as confirmed with polarized optical microscopy. Due to the presence of the azobenzene moieties, the LCs were photoresponsive, and a LC-to-isotropic phase transition could be obtained by irradiation with UV light. We envisage that the light-induced phase transition, in combination with the ionic nature of the LC, provides a route towards light-induced control over ion transport and conductance in these supramolecular complexes.

  16. Study of the controlled assembly of DNA gated PEI/Chitosan/SiO2 fluorescent sensor.

    Science.gov (United States)

    Chang, Zheng; Mi, Yinghao; Zheng, Xingwang

    2017-12-12

    In this paper, polyethylenimine (PEI) and Chitosan were simultaneously one-step doped into silicon dioxide (SiO2 ) nanoparticles to synthesize PEI/Chitosan/SiO2 composite nanoparticles. The polymer PEI contained a large amount of amino groups, which can realize the amino functionalized SiO2 nanoparticles. And, the good pore forming effect of Chitosan was introduced into SiO2 nanoparticles, and the resulting composite nanoparticles also had a porous structure. In pH 7.4 phosphate buffer solution (PBS), the amino groups of PEI had positive charges, and therefore the fluorescein sodium dye molecule can be loaded into the channels of PEI/Chitosan/SiO2 composite nanoparticles by electrostatic adsorption. Furthermore, utilizing the diversity of DNA molecular conformation, we designed a high sensitive controllable assembly of DNA gated fluorescent sensor based on PEI/Chitosan/SiO2 composite nanoparticles as loading materials. The factors affecting the sensing performance of the sensor were investigated, and the sensing mechanism was also further studied. Copyright © 2017 John Wiley & Sons, Ltd.

  17. Autonomous electrochromic assembly

    Energy Technology Data Exchange (ETDEWEB)

    Berland, Brian Spencer; Lanning, Bruce Roy; Stowell, Jr., Michael Wayne

    2015-03-10

    This disclosure describes system and methods for creating an autonomous electrochromic assembly, and systems and methods for use of the autonomous electrochromic assembly in combination with a window. Embodiments described herein include an electrochromic assembly that has an electrochromic device, an energy storage device, an energy collection device, and an electrochromic controller device. These devices may be combined into a unitary electrochromic insert assembly. The electrochromic assembly may have the capability of generating power sufficient to operate and control an electrochromic device. This control may occur through the application of a voltage to an electrochromic device to change its opacity state. The electrochromic assembly may be used in combination with a window.

  18. Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.

    Science.gov (United States)

    Noi, Ka Fung; Roozmand, Ali; Björnmalm, Mattias; Richardson, Joseph J; Franks, George V; Caruso, Frank

    2015-12-23

    Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications.

  19. Synthesis and Self-Assembly of Gold Nanoparticles by Chemically Modified Polyol Methods under Experimental Control

    Directory of Open Access Journals (Sweden)

    Nguyen Viet Long

    2013-01-01

    Full Text Available In our present research, bottom-up self-assembly of gold (Au nanoparticles on a flat copper (Cu substrate is performed by a facile method. The very interesting evidence of self-assembly of Au nanoparticles on the top of the thin assembled layer was observed by scanning electron microscopy (SEM. We had discovered one of the most general and simple methods for the self-assembly of metal nanoparticles. The general physical and chemical mechanisms of the evaporation process of the solvents can be used for self-assembly of the as-prepared nanoparticles. The important roles of molecules of the used solvents are very critical to self-assembly of the as-prepared Au nanoparticles in the case without using any polymers for those processes. It is clear that self-assembly of such one nanosystem of the uniform Au nanoparticles is fully examined. Finally, an exciting surface plasmon resonance (SPR phenomenon of the pure Au nanoparticles in the solvent was fully discovered in their exciting changes of the narrow and large SPR bands according to synthesis time. The SPR was considered as the collective oscillation of valence electrons of the surfaces of the pure Au nanoparticles in the solvent by incident ultraviolet-visible light. Then, the frequency of light photons matches the frequency of the oscillation of surface electrons of the Au nanoparticles that are excited.

  20. Self-Assembly of Cellulose Oligomers into Nanoribbon Network Structures Based on Kinetic Control of Enzymatic Oligomerization.

    Science.gov (United States)

    Serizawa, Takeshi; Fukaya, Yuka; Sawada, Toshiki

    2017-10-27

    The ability to chemically synthesize desired molecules followed by their in situ self-assembly in reaction solution has attracted much attention as a simple and environmentally friendly method to produce self-assembled nanostructures. In this study, α-D-glucose 1-phosphate monomers and cellobiose primers were subjected to cellodextrin phosphorylase-catalyzed reverse phosphorolysis reactions in aqueous solution in order to synthesize cellulose oligomers, which were then in situ self-assembled into crystalline nanoribbon network structures. The average degree-of-polymerization (DP) values of the cellulose oligomers were estimated to be approximately 7-8 with a certain degree of DP distribution. The cellulose oligomers crystallized with the cellulose II allomorph appeared to align perpendicularly to the base plane of the nanoribbons in an anti-parallel manner. Detailed analyses of reaction time dependence suggested that the production of nanoribbon network structures was kinetically controlled by the amount of water-insoluble cellulose oligomers produced.

  1. Subcritical-Water Extraction of Organics from Solid Matrices

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank; Patrick, Steven; Kirby, James; Bickler, Donald; Willis, Peter; Pelletier, Christine; Bryson, Charles

    2009-01-01

    An apparatus for extracting organic compounds from soils, sands, and other solid matrix materials utilizes water at subcritical temperature and pressure as a solvent. The apparatus, called subcritical water extractor (SCWE), is a prototype of subsystems of future instrumentation systems to be used in searching for organic compounds as signs of past or present life on Mars. An aqueous solution generated by an apparatus like this one can be analyzed by any of a variety of established chromatographic or spectroscopic means to detect the dissolved organic compound( s). The apparatus can be used on Earth: indeed, in proof-of-concept experiments, SCWE was used to extract amino acids from soils of the Atacama Desert (Chile), which was chosen because the dryness and other relevant soil conditions there approximate those on Mars. The design of the apparatus is based partly on the fact that the relative permittivity (also known as the dielectric constant) of liquid water varies with temperature and pressure. At a temperature of 30 C and a pressure of 0.1 MPa, the relative permittivity of water is 79.6, due to the strong dipole-dipole electrostatic interactions between individual molecular dipoles. As the temperature increases, increasing thermal energy causes increasing disorientation of molecular dipoles, with a consequent decrease in relative permittivity. For example, water at a temperature of 325 C and pressure of 20 MPa has a relative permittivity of 17.5, which is similar to the relative permittivities of such nonpolar organic solvents as 1-butanol (17.8). In the operation of this apparatus, the temperature and pressure of water are adjusted so that the water can be used in place of commonly used organic solvents to extract compounds that have dissimilar physical and chemical properties.

  2. Self-Assembly of Large-Scale Shape-Controlled DNA Nano-Structures

    Science.gov (United States)

    2014-12-16

    Polyhedra self-assembled from DNA tripods and characterized with 3D DNA- PAINT DNA self-assembly has produced diverse synthetic three-dimensional...edge widths of 100 nanometers. The structures were visualized by means of transmission electron microscopy and three-dimensional DNA- PAINT super...mild conditions, this seed grows into a larger cast structure that fills and thus replicates the cavity. We synthesized a variety of nanoparticles

  3. A Poly Adenine-Mediated Assembly Strategy for Designing Surface-Enhanced Resonance Raman Scattering Substrates in Controllable Manners.

    Science.gov (United States)

    Zhu, Ying; Jiang, Xiangxu; Wang, Houyu; Wang, Siyi; Wang, Hui; Sun, Bin; Su, Yuanyuan; He, Yao

    2015-07-07

    In this article, we introduce a Poly adenine (Poly A)-assisted fabrication method for rationally designing surface-enhanced resonance Raman scattering (SERRS) substrates in controllable and reliable manners, enabling construction of core-satellite SERRS assemblies in both aqueous and solid phase (e.g., symmetric core (Au)-satellite (Au) nanoassemblies (Au-Au NPs), and asymmetric Ag-Au NPs-decorated silicon wafers (Ag-Au NPs@Si)). Of particular significance, assembly density is able to be controlled by varying the length of the Poly A block (e.g., 10, 30, and 50 consecutive adenines at the 5' end of DNA sequence, Poly A10/A30/A50), producing the asymmetric core-satellite nanoassemblies with adjustable surface density of Au NPs assembly on core NPs surface. Based on quantitative interrogation of the relationship between SERRS performance and assemble density, the Ag-Au NPs@Si featuring the strongest SERRS enhancement factor (EF ≈ 10(7)) and excellent reproducibility can be achieved under optimal conditions. We further employ the resultant Ag-Au NPs@Si as a high-performance SERRS sensing platform for the selective and sensitive detection of mercury ions (Hg(2+)) in a real system, with a low detection limit of 100 fM, which is ∼5 orders of magnitude lower than the United States Environmental Protection Agency (USEPA)-defined limit (10 nM) in drinkable water. These results suggest the Poly A-mediated assembly method as new and powerful tools for designing high-performance SERRS substrates with controllable structures, facilitating improvement of sensitivity, reliability, and reproducibility of SERRS signals.

  4. Coupled Subcritical Water and Solid Phase Extraction for In-Situ Chemical Analysis Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leiden Measurement Technology (LMT) will design and develop a low volume analyte separation, concentration, and transfer system (ConTech), that couples a Subcritical...

  5. Controlling Interfacial Adhesion of Self-Assembled Polypeptide Fibrils for Novel Nanoelectromechanical System (NEMS Applications

    Directory of Open Access Journals (Sweden)

    Christopher Kossow

    2011-01-01

    Full Text Available The relative adhesion of two genetically engineered polypeptides termed as H6-(YEHKx21-H6 and C6-(YEHKX21-H6 has been investigated following growth and self-assembly on highly oriented pyrolytic graphite (HOPG, SiO2, Ni, and Au substrates to study covalent surface attachment via histidine (H and cysteine (C groups incorporated in the polypeptides. Both polypeptides formed predominantly bilayer fibrils upon deposition, in agreement with previous studies. The relative adhesion of polypeptide fibrils to the substrate, as well as intra-fibril cohesion, was examined via a forced-scanning method employing contact mode atomic force microscopy (AFM. H6-(YEHKx21-H6 polypeptide fibrils were observed to detach from Ni, Au, SiO2, and HOPG substrates at normal tip forces of 106 ± 10 nN, 21 ± 3 nN, 22 ± 3 nN, and 3 ± 1 nN, respectively. C6-(YEHKx21-H6 polypeptide fibrils were seen to detach from Au substrates at a normal spring force of 90 ± 10 nN. It is concluded that the H6-(YEHKx21-H6 and C6-(YEHKx21-H6 polypeptide fibrils are covalently attached to, respectively, Ni and Au substrates, which has important implications for the use of these materials for NEMS fabrication. The structural stability of deposited polypeptide fibrils was also evaluated by using normal tip forces less than those required for fibril detachment. H6-(YEHKx21-H6 polypeptide fibrils on Ni substrates were the most structurally stable compared to C6-(YEHKx21-H6 polypeptide fibrils on Au substrates. Controlled delayering of bilayer fibrils was also detected for sub-detachment normal forces.

  6. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    OpenAIRE

    Peng Hu; Gao-Wei Zhang; Long-Xiang Chen; Ming-Hou Liu

    2017-01-01

    Electrothermal energy storage (ETES) provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analys...

  7. Controllable self-assembly of NaREF4 upconversion nanoparticles and their distinctive fluorescence properties

    Science.gov (United States)

    Liu, Xiaoxia; Ni, Yaru; Zhu, Cheng; Fang, Liang; Kou, Jiahui; Lu, Chunhua; Xu, Zhongzi

    2016-07-01

    The paper presents the growth of hexagonal NaYF4:Yb3+, Tm3+ nanocrystals with tunable sizes induced by different contents of doped Yb3+ ions (10%-99.5%) using the thermal decomposition method. These nanoparticles, which have different sizes, are then self-assembled at the interface of cyclohexane and ethylene and transferred onto a normal glass slide. It is found that the size of nanoparticles directs their self-assembly. Due to the appropriate size of 40.5 nm, 15% Yb3+ ions doped nanoparticles are able to be self-assembled into an ordered inorganic monolayer membrane with a large area of about 10 × 10 μm2. More importantly, the obvious short-wave (300-500 nm) fluorescence improvement of the ordered 2D self-assembly structure is observed to be relative to disordered nanoparticles, which is because intrinsic absorption and scattering of upconversion nanoparticles leads to the self-loss of fluorescence, especially the short-wave fluorescence inside the disordered structure, and the relative emission of short-wave fluorescence is reduced. The construction of a 2D self-assembly structure can effectively avoid this and improve the radiated short-wave fluorescence, especially UV photons, and is able to direct the design of new types of solid-state optical materials in many fields.

  8. Regioisomeric control induced by DABCO coordination to rotatable self-assembled bis- and tetraporphyrin α,γ-cyclic octapeptide dimers.

    Science.gov (United States)

    Hernández-Eguía, Laura P; Brea, Roberto J; Castedo, Luis; Ballester, Pablo; Granja, Juan R

    2011-01-24

    The design and synthesis of two α,γ-cyclic octapeptides decorated with one and two Zn-porphyrin units in their periphery is described. In nonpolar organic solvents the α,γ-cyclic octapeptides quantitatively self-assemble into Zn-bis- or -tetraporphyrin architectures that could act as molecular tweezers. The self-assembly process, however, is not regioselective and affords a mixture of different regioisomers that are involved in chemical exchange processes. The regioisomers with the Zn-porphyrin units positioned in register with respect to each other are proposed to be the less abundant species in the solution mixture. It has been demonstrated that the coordination of 1,4-diazabicyclo[2.2.2]octane (DABCO) to the supramolecular bis- or tetraporphyrin tweezers is an effective way to achieve regioisomeric control of the self-assembled mixture of dimers. Thus, DABCO functions as an external molecular trigger and, when used under strict stoichiometric control with respect to the Zn-porphyrin units, provokes the exclusive formation of self-assembled dimers with a cofacial arrangement of Zn-porphyrin units through the formation of sandwich-type complexes. The use of excess DABCO fragments the sandwich complexes and affords open dimers of high stoichiometry with DABCO molecules axially monocoordinated to the Zn-porphyrin units, probably as a regioisomeric mixture. In the case of Zn-tetraporphyrin tweezers, the ditopic coordination of DABCO at the two binding sites shows a moderate positive cooperativity factor, αP=5. These assemblies have potential applications as light-induced energy and electron-transfer switches regulated by DABCO coordination; such applications would require the introduction of additional chromophores in the cyclic peptide scaffold. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Subcritical Noise Analysis Measurements with Fresh and Spent Research Reactor Fuels Elements

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, T.E.; Mihalczo, J.T.; Kryter, R.C.; Miller, V.C.

    1999-02-01

    The verification of the subcriticality is of utmost importance for the safe transportation and storage of nuclear reactor fuels. Transportation containers and storage facilities are designed such that nuclear fuels remain in a subcritical state. Such designs often involve excess conservatism because of the lack of relevant experimental data to verify the accuracy of Monte Carlo codes used in nuclear criticality safety analyses. A joint experimental research program between Oak Ridge National Laboratory, Westinghouse Safety Management Solutions, Inc., and the University of Missouri was initiated to obtain measured quantities that could be directly related to the subcriticality of simple arrays of Missouri University Research Reactor (MURR) fuel elements. A series of measurement were performed to assess the reactivity of materials such as BORAL, stainless steel, aluminum, and lead that are typically used in the construction of shipping casks. These materials were positioned between the fuel elements. In addition, a limited number of measurements were performed with configurations of fresh and spent (irradiated) fuel elements to ascertain the reactivity of the spent fuel elements. In these experiments, fresh fuel elements were replaced by spent fuel elements such that the subcritical reactivity change could be measured. The results of these measurements were used by Westinghouse Safety Management Solutions to determine the subcriticality of MURR fuel elements isolated by absorbing materials. The measurements were interpreted using the MCNP-DSP Monte Carlo code to obtain the subcritical neutron multiplication factor k(sub eff), and the bias in K(sub eff) that are used in criticality safety analyses.

  10. Subcritical Water Hydrolysis of Peptides: Amino Acid Side-Chain Modifications

    Science.gov (United States)

    Powell, Thomas; Bowra, Steve; Cooper, Helen J.

    2017-09-01

    Previously we have shown that subcritical water may be used as an alternative to enzymatic digestion in the proteolysis of proteins for bottom-up proteomics. Subcritical water hydrolysis of proteins was shown to result in protein sequence coverages greater than or equal to that obtained following digestion with trypsin; however, the percentage of peptide spectral matches for the samples treated with trypsin were consistently greater than for those treated with subcritical water. This observation suggests that in addition to cleavage of the peptide bond, subcritical water treatment results in other hydrolysis products, possibly due to modifications of amino acid side chains. Here, a model peptide comprising all common amino acid residues (VQSIKCADFLHYMENPTWGR) and two further model peptides (VCFQYMDRGDR and VQSIKADFLHYENPTWGR) were treated with subcritical water with the aim of probing any induced amino acid side-chain modifications. The hydrolysis products were analyzed by direct infusion electrospray tandem mass spectrometry, either collision-induced dissociation or electron transfer dissociation, and liquid chromatography collision-induced dissociation tandem mass spectrometry. The results show preferential oxidation of cysteine to sulfinic and sulfonic acid, and oxidation of methionine. In the absence of cysteine and methionine, oxidation of tryptophan was observed. In addition, water loss from aspartic acid and C-terminal amidation were observed in harsher subcritical water conditions. [Figure not available: see fulltext.

  11. Understanding and Controlling Nanoscale Morphology in Self-Assembled Semiconducting Materials

    Science.gov (United States)

    Kang, Hyeyeon

    Self-assembled semiconducting materials have been rapidly developed for a range of applications. This work aims to control the morphology of nanostructured semiconductors to understand how their functions arise from the structural properties. The first part of this dissertation focuses on the formation of a bulk-heterojunction (BHJ) in the active layer of organic photovoltaics (OPV). A BHJ is a bicontinuous interpenetrating network of organic components. The phase separation of the electron donor and the acceptor is required to achieve a BHJ structure in the nanostructured morphology, which promotes an efficient charge transportation. The use of solvent additive is one of the strategies to control the spontaneous phase separation during the film formation. Low vapor pressure solvent additives are introduced to a polymer casting solution in a sequentially processed OPV system, to study the swelling effect on the phase separation. In particular, the change in crystallinity and vertical mixing will be intensively studied upon polymer swelling. As another strategy, we introduce a molecular structure change to fullerene derivatives. A small structural variation leads to a large enough contrast of their surface energy, which is attributed to different vertical phase separation in the active layer. It eventually allows us to examine photovoltaic performance and device physics. In the second part, mesoporous inorganic films are investigated by preparation from a nanocrystal solution or sol-gel precursors for solar energy applications. Mesoporous nanocrystal-based titania is synthesized for inorganic/organic hybrid solar cells. The effect of surface modification is examined by anchoring a fullerene derivative on to titania surface. 3D interconnected mesoporous tantalum nitride films are prepared via sol-gel method as photoanodes in solar water splitting. The simple synthetic method using polymer template enables us to successfully prepare nitride films with excellent pore

  12. Controlled Self-Assembly of Cyclophane Amphiphiles: From 1D Nanofibers to Ultrathin 2D Topological Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Zhengxu; Li, Lianwei; Lo, Wai-Yip; Zhao, Donglin; Wu, Qinghe; Zhang, Na; Su, Yu-An; Chen, Wei; Yu, Luping

    2016-07-05

    A novel series of amphiphilic TC-PEG molecules were designed and synthesized based on the orthogonal cyclophane unit. These molecules were able to self-assemble from 1D nanofibers and nanobelts to 2D ultrathin nanosheets (3 nm thick) in a controlled way by tuning the length of PEG side chains. The special structure of the cyclophane moiety allowed control in construction of nanostructures through programmed noncovalent interactions (hydrophobic hydrophilic interaction and pi-pi interaction). The self-assembled nanostructures were characterized by combining real space imaging (TEM, SEM, and AFM) and reciprocal space scattering (GIWAXS) techniques. This unique supramolecular system may provide a new strategy for the design of materials with tunable nanomorphology and functionality.

  13. Design report of the disposal canister for twelve fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Raiko, H. [VTT Energy, Espoo (Finland); Salo, J.P. [Posiva Oy, Helsinki (Finland)

    1999-05-01

    The report provides a summary of the design of the canister for final disposal of spent nuclear fuel. The canister structure consists of a cylindrical massive nodular graphite cast iron insert covered by a 50 mm thick copper overlay. The capacity of the canister is 12 assemblies of BWR or VVER 440 fuel. The canister shall be tight with a high probability for about 100 000 years. The good and long lasting tightness requires: (1) The good initial tightness that is achieved by high quality requirements and extensive quality control, (2) The good corrosion resistance, which is obtained by the overpack of oxygen free copper, and (3) Mechanical strength of the canister, that is ensured by analyses (the following loads are considered: hydrostatic pressure, even and uneven swelling pressure of bentonite, thermal effects, and elevated hydrostatic pressure during glaciation. The allowed stresses and strains are set in such a way that reasonable engineering safety factors are obtained in all assessed design base loading cases). The canister shall limit the radiation dose rate outside the canister to minimise the radiolysis of the water in the vicinity of the canister. The canister insert shall keep the fuel assemblies in a subcritical configuration even if the void in the canister is filled with water due to postulated leakage. The design basis of the canister is set, the performed analyses are summarised and the results are assessed and discussed in the report. (orig.) 35 refs.

  14. Controllable synthesis of self-assembly Co3O4 nanoflake microspheres for electrochemical performance

    Science.gov (United States)

    Liu, Fangyan; Zhang, Binbin; Su, Hai; Zhang, Haitao; Zhang, Lei; Yang, Weiqing

    2016-09-01

    Tuning the ratios of ethanol to water, self-assembling microspheres composed of Co3O4 nanoflakes are synthesized by the hydrothermal method. The scanning electron microscopy (SEM) images of as-grown samples obviously show that the dispersive multilayered structures gradually change into micro/nanobelts and cubic blocks structures, and then into the desired self-assembled microspheres with increasing ratios of ethanol to water. Also, all the x-ray diffraction (XRD) patterns evidently demonstrate that all obtained Co3O4 has cubic crystal structure. The corresponding synthesis mechanism is discussed in detail. More importantly, the unique self-assembling Co3O4 nanoflake microspheres have excellent electrochemical performance with large specific capacitance, good rate capability and excellent cycling performance, evidently presenting a potential capability of Co3O4 nanoflake microspheres to act as electrode materials for supercapacitors in sustainable power sources.

  15. Investigation of parameters controlling the dielectrophoretic assembly of carbon nanotubes on microelectrodes

    DEFF Research Database (Denmark)

    Dimaki, Maria; Bøggild, Peter

    2008-01-01

    Networks of single-walled carbon nanotubes were assembled onto microelectrodes by dielectrophoresis. The dependence of the obtained networks on several assembly parameters such as bias voltage, field application time, frequency, electrode geometry and the nanotube solvent were investigated both...... structurally and electrically. Reproducible differences in morphological and electrical properties were observed for the parameters investigated. Application of a bias voltage above 10 V for more than 30 seconds with nanotubes in an SDS solution, resulted in dense networks with a relatively low resistance...... in the 10 k Omega regime. On the other hand, individual nanotubes and bundles were assembled with lower voltages applied for less than 10 seconds and with other nanotubes solutions. The experimental results were combined with theoretical calculations in order to find a geometry and voltage independent...

  16. RNA-controlled assembly of tobacco mosaic virus-derived complex structures: from nanoboomerangs to tetrapods

    Science.gov (United States)

    Eber, Fabian J.; Eiben, Sabine; Jeske, Holger; Wege, Christina

    2014-11-01

    The in vitro assembly of artificial nanotubular nucleoprotein shapes based on tobacco mosaic virus-(TMV-)-derived building blocks yielded different spatial organizations of viral coat protein subunits on genetically engineered RNA molecules, containing two or multiple TMV origins of assembly (OAs). The growth of kinked nanoboomerangs as well as of branched multipods was determined by the encapsidated RNAs. A largely simultaneous initiation at two origins and subsequent bidirectional tube elongation could be visualized by transmission electron microscopy of intermediates and final products. Collision of the nascent tubes' ends produced angular particles with well-defined arm lengths. RNAs with three to five OAs generated branched multipods with a maximum of four arms. The potential of such an RNA-directed self-assembly of uncommon nanotubular architectures for the fabrication of complex multivalent nanotemplates used in functional hybrid materials is discussed.

  17. Light-controlled drug releasing polymer films combining LbL self-assembly and host-guest interactions

    OpenAIRE

    Li, J; He, L.; J. Wang; Zhang, Z. T.; Shi, J.; X. Z. Zhang(Department of Nuclear Physics and Beijing Tandem Accelerator National Laboratory, Beijing, China); Cao, Y.P.; Y. Chen

    2014-01-01

    By combining LbL (layer-by-layer) self-assembly approach and host-guest interactions, a unique multilayer film was constructed and employed for a light-controlled drug release system. The drug molecules can be loaded and released into the resulting polyelectrolyte multilayers containing azobenzene (Azo) function groups by using the irradiation of visible light and UV light alternately. The photo-sensitivity of the multilayer films was studied through UV-vis spectrum, fluorescence spectrum and...

  18. Corrosion Assessment of Candidate Materials for the SHINE Subcritical Assembly Vessel and Components FY15 Report

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-01-01

    In the previous report of this series, a literature review was performed to assess the potential for substantial corrosion issues associated with the proposed SHINE process conditions to produce 99Mo. Following the initial review, substantial laboratory corrosion testing was performed emphasizing immersion and vapor-phase exposure of candidate alloys in a wide variety of solution chemistries and temperatures representative of potential exposure conditions. Stress corrosion cracking was not identified in any of the exposures up to 10 days at 80°C and 10 additional days at 93°C. Mechanical properties and specimen fracture face features resulting from slow-strain rate tests further supported a lack of sensitivity of these alloys to stress corrosion cracking. Fluid velocity was found not to be an important variable (0 to ~3 m/s) in the corrosion of candidate alloys at room temperature and 50°C. Uranium in solution was not found to adversely influence potential erosion-corrosion. Potentially intense radiolysis conditions slightly accelerated the general corrosion of candidate alloys, but no materials were observed to exhibit an annualized rate above 10 μm/y.

  19. Corrosion Assessment of Candidate Materials for the SHINE Subcritical Assembly Vessel and Components FY14 Report

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-10-01

    Laboratory corrosion testing of candidate alloys—including Zr-4 and Zr-2.5Nb representing the target solution vessel, and 316L, 2304, 304L, and 17-4 PH stainless steels representing process piping and balance-of-plant components—was performed in support of the proposed SHINE process to produce 99Mo from low-enriched uranium. The test solutions used depleted uranyl sulfate in various concentrations and incorporated a range of temperatures, excess sulfuric acid concentrations, nitric acid additions (to simulate radiolysis product generation), and iodine additions. Testing involved static immersion of coupons in solution and in the vapor above the solution, and was extended to include planned-interval tests to examine details associated with stainless steel corrosion in environments containing iodine species. A large number of galvanic tests featuring couples between a stainless steel and a zirconium-based alloy were performed, and limited vibratory horn testing was incorporated to explore potential erosion/corrosion features of compatibility. In all cases, corrosion of the zirconium alloys was observed to be minimal, with corrosion rates based on weight loss calculated to be less than 0.1 mil/year with no change in surface roughness. The resulting passive film appeared to be ZrO2 with variations in thickness that influence apparent coloration (toward light brown for thicker films). Galvanic coupling with various stainless steels in selected exposures had no discernable effect on appearance, surface roughness, or corrosion rate. Erosion/corrosion behavior was the same for zirconium alloys in uranyl sulfate solutions and in sodium sulfate solutions adjusted to a similar pH, suggesting there was no negative effect of uranium resulting from fluid dynamic conditions aggressive to the passive film. Corrosion of the candidate stainless steels was similarly modest across the entire range of exposures. However, some sensitivity to corrosion of the stainless steels was observed in solutions with 50 wppm iodine (the actual SHINE process expects 0.1–1 wppm) with the highest corrosion rates (up to ~6 mil/year) observed on specimens exposed in the vapor phase. Lower concentrations of iodine species (5 or 28 wppm) proved much less corrosive, and the planned-interval data indicated that metal corrodibility decreased with time for all immersed exposures and, with one minor exception, all vapor exposures. Little change in susceptibility to corrosion was observed as a result of nitric acid additions to the test environment (simulating radiolysis products). The trend toward reduced corrosion (immersion and vapor phase) with decreasing iodine concentration suggests that, at the expected conditions in the SHINE process, it is unlikely that iodine species will generate a general corrosion concern for the candidate stainless steels.

  20. Size control and compartmentalization in self-assembled nano-structures of a multisegment amphiphilew

    NARCIS (Netherlands)

    Boekhoven, J.; Van Rijn, P.; Brizard, A.M.; Stuart, M.C.A.; Van Esch, J.H.

    2010-01-01

    A ‘‘multisegment amphiphile’’ has been synthesized by covalently connecting two well known building blocks, a gelator and a micelle forming surfactant. Self-assembly results in the formation of compartmentalized nano-object displaying properties inherited from both parents.

  1. Controlling Peptide Self-Assembly through a Native Chemical Ligation/Desulfurization Strategy.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Konda, Maruthi; Biswas, Sagar; Das, Apurba K

    2016-03-18

    Self-assembled peptides were synthesized by using a native chemical ligation (NCL)/desulfurization strategy that maintained the chemical diversity of the self-assembled peptides. Herein, we employed oxo-ester-mediated NCL reactions to incorporate cysteine, a cysteine-based dipeptide, and a sterically hindered unnatural amino acid (penicillamine) into peptides. Self-assembly of the peptides resulted in the formation of self-supporting gels. Microscopy analysis indicated the formation of helical nanofibers, which were responsible for the formation of gel matrices. The self-assembly of the ligated peptides was governed by covalent and non-covalent interactions, as confirmed by FTIR, CD, fluorescence spectroscopy, and MS (ESI) analyses. Peptide disassembly was induced by desulfurization reactions with tris(2-carboxyethyl)phosphine (TCEP) and glutathione at 80 °C. Desulfurization reactions of the ligated peptides converted the Cys and penicillamine functionalities into Ala and Val moieties, respectively. The self-supporting gels showed significant shear-thinning and thixotropic properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Structure-based engineering of papillomavirus major capsid L1: controlling particle assembly

    Directory of Open Access Journals (Sweden)

    Dasgupta Jhimli

    2007-01-01

    Full Text Available Abstract The outer shell of the papillomavirus particle is comprised of 72 pentamers of the major capsid L1 protein arranged on a T = 7 icosahedral lattice. The recombinant L1 can form T = 7 virus-like particles in vitro. The crystal structure of a T = 7 papilloma virion has not yet been determined; however, the crystal structure of a T = 1 particle containing 12 pentamers is known. The T = 1 structure reveals that helix-helix interactions, through three helices–h2, h3, and h4–near the C-terminus of L1, mediate the inter-pentameric bonding that is responsible for T = 1 assembly. Based on the T = 1 crystal structure, we have generated a set of internal deletions to test the role of the three C-terminal helices in T = 7 assembly. We have demonstrated that the h2, h3, and h4 near the C-terminal end of L1 are important for the L1 structure and particle assembly. In particular, we found that h2 and h3 are essential for L1 folding and pentamer formation, whereas h4 is indispensable for the assembly of not only T1, but also of the T7 virus-like particle.

  3. Controlling Molecular Motion, Assembly and Coupling as a Step towards Molecular Actuators

    Science.gov (United States)

    Murphy, Colin James

    changes in the supramolecular self-assembly of thioethers. Chapter 9 details how the ordering and length of surface-bound hydrogen-bonded chains of methanol are dictated by the underlying surface and examines an unreported chiral meta-stable methanol hexamer. Single-molecule measurements can answer many of the current questions in the field of molecular machines and lead to control of molecular motion. Development of mechanisms to direct molecular motion and to couple this motion to external systems is crucial for the rational design of new molecular machinery with functionalities such as mass transport, propulsion, separations, sensing, signaling and chemical reactions.

  4. Enhancement of a 252Cf-based neutron beam via subcritical multiplication for neutron capture therapy.

    Science.gov (United States)

    Wang, C K; Zino, J F; Kessler, G

    2000-01-01

    Previous studies indicated that an epithermal-neutron beam based on bare 252Cf is not feasible for neutron capture therapy (NCT). It was reported that a clinically useful epithermal-neutron beam requires a minimum of 1.0 g of 252Cf, which is more than twice the US current annual supply. However, it was reasoned that the required quantity of 252Cf could be dramatically reduced when used with a subcritical multiplying assembly (SMA). This reasoning is based on the assumption that the epithermal-neutron beam intensity for NCT is directly proportional to the fission neutron population, and that the neutron multiplying factor of the SMA can be estimated by 1/(1 - k(eff)). We have performed detailed Monte Carlo calculations to investigate the validity of the above reasoning. Our results show that 1/(1 - k(eff)) grossly overestimates the beam enhancement factor for NCT. For example, Monte Carlo calculations predict a beam enhancement factor of 6.0 for an optimized SMA geometry with k(eff) = 0.968. This factor is much less than 31 predicted by 1/(1 - k(eff)). The overestimation is due to the fact that most of the neutrons produced in the SMA are self-shielded, whereas self-shielding is negligible in a bare 252Cf source. Since the beam intensity of a 0.1 g 252Cf with the optimized SMA enhancement is still more than an order of magnitude too low compared to the existing reactor beams, we conclude that the enhancement via an SMA for a 252Cf-based epithermal-neutron beam is inadequate for NCT.

  5. Key aromatic/hydrophobic amino acids controlling a cross-amyloid peptide interaction versus amyloid self-assembly.

    Science.gov (United States)

    Bakou, Maria; Hille, Kathleen; Kracklauer, Michael; Spanopoulou, Anna; Frost, Christina V; Malideli, Eleni; Yan, Li-Mei; Caporale, Andrea; Zacharias, Martin; Kapurniotu, Aphrodite

    2017-09-01

    The interaction of the intrinsically disordered polypeptide islet amyloid polypeptide (IAPP), which is associated with type 2 diabetes (T2D), with the Alzheimer's disease amyloid-β (Aβ) peptide modulates their self-assembly into amyloid fibrils and may link the pathogeneses of these two cell-degenerative diseases. However, the molecular determinants of this interaction remain elusive. Using a systematic alanine scan approach, fluorescence spectroscopy, and other biophysical methods, including heterocomplex pulldown assays, far-UV CD spectroscopy, the thioflavin T binding assay, transmission EM, and molecular dynamics simulations, here we identified single aromatic/hydrophobic residues within the amyloid core IAPP region as hot spots or key residues of its cross-interaction with Aβ40(42) peptide. Importantly, we also find that none of these residues in isolation plays a key role in IAPP self-assembly, whereas simultaneous substitution of four aromatic/hydrophobic residues with Ala dramatically impairs both IAPP self-assembly and hetero-assembly with Aβ40(42). Furthermore, our experiments yielded several novel IAPP analogs, whose sequences are highly similar to that of IAPP but have distinct amyloid self- or cross-interaction potentials. The identified similarities and major differences controlling IAPP cross-peptide interaction with Aβ40(42) versus its amyloid self-assembly offer a molecular basis for understanding the underlying mechanisms. We propose that these insights will aid in designing intervention strategies and novel IAPP analogs for the management of type 2 diabetes, Alzheimer's disease, or other diseases related to IAPP dysfunction or cross-amyloid interactions. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Subcritical hydrothermal conversion of organic wastes and biomass. Reaction pathways

    Directory of Open Access Journals (Sweden)

    Alejandro Amadeus Castro Vega

    2010-04-01

    Full Text Available Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requi- res previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added- value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary tralectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

  7. Effect of fluid salinity on subcritical crack propagation in calcite

    Science.gov (United States)

    Rostom, Fatma; Røyne, Anja; Dysthe, Dag Kristian; Renard, François

    2013-01-01

    The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing responsible for a ductile deformation of rocks under crustal conditions. In the present study, the double-torsion technique was used to measure the effect of fluid chemistry on the slow propagation of cracks in calcite single crystals at room temperature. Time-lapse images and measurements of force and load-point displacement allowed accurate characterization of crack velocities in a range of 10- 8 to 10- 4 m/s. Velocity curves as a function of energy-release rates were obtained for different fluid compositions, varying NH4Cl and NaCl concentrations. Our results show the presence of a threshold in fluid composition, separating two regimes: weakening conditions where the crack propagation is favored, and strengthening conditions where crack propagation slows down. We suggest that electrostatic surface forces that modify the repulsion forces between the two surfaces of the crack may be responsible for this behavior.

  8. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Qin, Guangyong

    2017-03-30

    As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE) technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  9. The Chain-Length Distribution in Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Texas A & M Univ., College Station, TX (United States)

    2000-06-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.

  10. Catalytic upgrading of duckweed biocrude in subcritical water.

    Science.gov (United States)

    Zhang, Caicai; Duan, Peigao; Xu, Yuping; Wang, Bing; Wang, Feng; Zhang, Lei

    2014-08-01

    Herein, a duckweed biocrude produced from the hydrothermal liquefaction of Lemna minor was treated in subcritical water with added H₂. Effects of several different commercially available materials such as Ru/C, Pd/C, Pt/C, Pt/γ-Al₂O₃, Pt/C-sulfide, Rh/γ-Al₂O₃, activated carbon, MoS₂, Mo₂C, Co-Mo/γ-Al₂O₃, and zeolite on the yields of product fractions and the deoxygenation, denitrogenation, and desulfurization of biocrude at 350°C were examined, respectively. All the materials showed catalytic activity for deoxygenation and desulfurization of the biocrude and only Ru/C showed activity for denitrogenation. Of those catalysts examined, Pt/C showed the best performance for deoxygenation. Among all the upgraded oils, the oil produced with Ru/C shows the lowest sulfur, the highest hydrocarbon content (25.6%), the highest energy recovery (85.5%), and the highest higher heating value (42.6 MJ/kg). The gaseous products were mainly unreacted H₂, CH₄, CO₂, and C₂H6. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea

    Directory of Open Access Journals (Sweden)

    Yating Zhang

    2017-03-01

    Full Text Available As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  12. Enhanced Capabilities for Subcritical Experiments (ECSE) Risk Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Mary Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Process Modeling and Analysis Group

    2016-05-02

    Risk is a factor, element, constraint, or course of action that introduces an uncertainty of outcome that could impact project objectives. Risk is an inherent part of all activities, whether the activity is simple and small, or large and complex. Risk management is a process that identifies, evaluates, handles, and monitors risks that have the potential to affect project success. The risk management process spans the entire project, from its initiation to its successful completion and closeout, including both technical and programmatic (non-technical) risks. This Risk Management Plan (RMP) defines the process to be used for identifying, evaluating, handling, and monitoring risks as part of the overall management of the Enhanced Capabilities for Subcritical Experiments (ECSE) ‘Project’. Given the changing nature of the project environment, risk management is essentially an ongoing and iterative process, which applies the best efforts of a knowledgeable project staff to a suite of focused and prioritized concerns. The risk management process itself must be continually applied throughout the project life cycle. This document was prepared in accordance with DOE O 413.3B, Program and Project Management for the Acquisition of Capital Assets, its associated guide for risk management DOE G 413.3-7, Risk Management Guide, and LANL ADPM AP-350-204, Risk and Opportunity Management.

  13. Controlled graphene oxide assembly on silver nanocube monolayers for SERS detection: dependence on nanocube packing procedure

    Directory of Open Access Journals (Sweden)

    Martina Banchelli

    2016-01-01

    Full Text Available Hybrid graphene oxide/silver nanocubes (GO/AgNCs arrays for surface-enhanced Raman spectroscopy (SERS applications were prepared by means of two procedures differing for the method used in the assembly of the silver nanocubes onto the surface: Langmuir–Blodgett (LB transfer and direct sequential physisorption of silver nanocubes (AgNCs. Adsorption of graphene oxide (GO flakes on the AgNC assemblies obtained with both procedures was monitored by quartz crystal microbalance (QCM technique as a function of GO bulk concentration. The experiment provided values of the adsorbed GO mass on the AgNC array and the GO saturation limit as well as the thickness and the viscoelastic properties of the GO film. Atomic force microscopy (AFM measurements of the resulting samples revealed that a similar surface coverage was achieved with both procedures but with a different distribution of silver nanoparticles. In the GO covered LB film, the AgNC distribution is characterized by densely packed regions alternating with empty surface areas. On the other hand, AgNCs are more homogeneously dispersed over the entire sensor surface when the nanocubes spontaneously adsorb from solution. In this case, the assembly results in less-packed silver nanostructures with higher inter-cube distance. For the two assembled substrates, AFM of silver nanocubes layers fully covered with GO revealed the presence of a homogeneous, flexible and smooth GO sheet folding over the silver nanocubes and extending onto the bare surface. Preliminary SERS experiments on adenine showed a higher SERS enhancement factor for GO on Langmuir–Blodgett films of AgNCs with respect to bare AgNC systems. Conversely, poor SERS enhancement for adenine resulted for GO-covered AgNCs obtained by spontaneous adsorption. This indicated that the assembly and packing of AgNCs obtained in this way, although more homogeneous over the substrate surface, is not as effective for SERS analysis.

  14. Electrokinetic stringency control in self-assembled monolayer-based biosensors for multiplex urinary tract infection diagnosis.

    Science.gov (United States)

    Liu, Tingting; Sin, Mandy L Y; Pyne, Jeff D; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2014-01-01

    Rapid detection of bacterial pathogens is critical toward judicious management of infectious diseases. Herein, we demonstrate an in situ electrokinetic stringency control approach for a self-assembled monolayer-based electrochemical biosensor toward urinary tract infection diagnosis. The in situ electrokinetic stringency control technique generates Joule heating induced temperature rise and electrothermal fluid motion directly on the sensor to improve its performance for detecting bacterial 16S rRNA, a phylogenetic biomarker. The dependence of the hybridization efficiency reveals that in situ electrokinetic stringency control is capable of discriminating single-base mismatches. With electrokinetic stringency control, the background noise due to the matrix effects of clinical urine samples can be reduced by 60%. The applicability of the system is demonstrated by multiplex detection of three uropathogenic clinical isolates with similar 16S rRNA sequences. The results demonstrate that electrokinetic stringency control can significantly improve the signal-to-noise ratio of the biosensor for multiplex urinary tract infection diagnosis. Urinary tract infections remain a significant cause of mortality and morbidity as secondary conditions often related to chronic diseases or to immunosuppression. Rapid and sensitive identification of the causative organisms is critical in the appropriate management of this condition. These investigators demonstrate an in situ electrokinetic stringency control approach for a self-assembled monolayer-based electrochemical biosensor toward urinary tract infection diagnosis, establishing that such an approach significantly improves the biosensor's signal-to-noise ratio. © 2013.

  15. Controlled positioning of self-assembled InAs quantum dots on (1 1 0) GaAs

    Science.gov (United States)

    Schuh, D.; Bauer, J.; Uccelli, E.; Schulz, R.; Kress, A.; Hofbauer, F.; Finley, J. J.; Abstreiter, G.

    2005-02-01

    We report on a new approach for positioning of self-assembled InAs quantum dots on (1 1 0) GaAs with nanometer precision. By combining self-assembly of quantum dots with molecular beam epitaxy on in situ cleaved surfaces (cleaved-edge overgrowth) we have successfully fabricated arrays of long-range ordered InAs quantum dots. Both atomic force microscopy and micro-photoluminescence measurements demonstrate the ability to control position and ordering of the quantum dots with epitaxial precision as well as size and size homogeneity. Furthermore, photoluminescence investigations on dot ensembles and on single dots confirm the high homogeneity and the excellent optical quality of the quantum dots fabricated.

  16. Time lapse microscopy of temperature control during self-assembly of 3D DNA crystals

    Science.gov (United States)

    Conn, Fiona W.; Jong, Michael Alexander; Tan, Andre; Tseng, Robert; Park, Eunice; Ohayon, Yoel P.; Sha, Ruojie; Mao, Chengde; Seeman, Nadrian C.

    2017-10-01

    DNA nanostructures are created by exploiting the high fidelity base-pairing interactions of double-stranded branched DNA molecules. These structures present a convenient medium for the self-assembly of macroscopic 3D crystals. In some self-assemblies in this system, crystals can be formed by lowering the temperature, and they can be dissolved by raising it. The ability to monitor the formation and melting of these crystals yields information that can be used to monitor crystal formation and growth. Here, we describe the development of an inexpensive tool that enables direct observation of the crystal growth process as a function of both time and temperature. Using the hanging-drop crystallization of the well-characterized 2-turn DNA tensegrity triangle motif for our model system, its response to temperature has been characterized visually.

  17. Selective Area Control of Self-Assembled Pattern Architecture Using a Lithographically Patternable Block Copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Black, C.T.; Bosworth, J.K.; Obert C.K.

    2009-07-01

    We leverage distinctive chemical properties of the diblock copolymer poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) to create for the first time high-resolution selective-area regions of two different block copolymer phase morphologies. Exposure of thin films of poly({alpha}-methylstyrene)-block-poly(4-hydroxystyrene) to nonselective or block-selective solvent vapors results in polymer phase separation and self-assembly of patterns of cylindrical-phase or kinetically trapped spherical-phases, respectively. Poly(4-hydroxystyrene) acts as a high-resolution negative-tone photoresist in the presence of small amounts of a photoacid generator and cross-linker, undergoing radiation-induced cross-linking upon exposure to ultraviolet light or an electron beam. We use lithographic exposure to lock one self-assembled phase morphology in specific sample areas as small as 100 nm in width prior to film exposure to a subsequent solvent vapor to form a second self-assembled morphology in unexposed wafer areas.

  18. Controllable fabrication of lotus-leaf-like superhydrophobic surface on copper foil by self-assembly

    Science.gov (United States)

    Yuan, Zhiqing; Wang, Xian; Bin, Jiping; Wang, Menglei; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Chen, Hong

    2014-09-01

    A novel approach was developed to fabricate a lotus-leaf-like superhydrophobic surface on a copper foil by simple self-assembly method with the assistance of the porous PDMS template which was used to adjust the oxidized parts of the copper foil surface before self-assembly. The results showed a series of beautiful flower-like microstructures resulting from the self-assembly of cupric stearate that were distributed at regular intervals on the as-prepared copper foil surface similar to the papillae of lotus leaf surface. The water contact angle of the as-prepared copper surface was up to 161° and its sliding angle was only 3°. Its great superhydrophobicity could be kept unchanged after 6 months in air. The formation mechanism of the lotus-leaf-like structure was discussed. This simple and low-cost method is expected to be applied to design and prepare complicated superhydrophobic surfaces with beautiful regular microstructures on different substrates such as stainless steel, zinc, and so on.

  19. Replicating centromeric chromatin: Spatial and temporal control of CENP-A assembly

    Energy Technology Data Exchange (ETDEWEB)

    Nechemia-Arbely, Yael; Fachinetti, Daniele; Cleveland, Don W., E-mail: dcleveland@ucsd.edu

    2012-07-15

    The centromere is the fundamental unit for insuring chromosome inheritance. This complex region has a distinct type of chromatin in which histone H3 is replaced by a structurally different homologue identified in humans as CENP-A. In metazoans, specific DNA sequences are neither required nor sufficient for centromere identity. Rather, an epigenetic mark comprised of CENP-A containing chromatin is thought to be the major determinant of centromere identity. In this view, CENP-A deposition and chromatin assembly are fundamental processes for the maintenance of centromeric identity across mitotic and meiotic divisions. Several lines of evidence support CENP-A deposition in metazoans occurring at only one time in the cell cycle. Such cell cycle-dependent loading of CENP-A is found in divergent species from human to fission yeast, albeit with differences in the cell cycle point at which CENP-A is assembled. Cell cycle dependent CENP-A deposition requires multiple assembly factors for its deposition and maintenance. This review discusses the regulation of new CENP-A deposition and its relevance to centromere identity and inheritance.

  20. High power ring methods and accelerator driven subcritical reactor application

    Energy Technology Data Exchange (ETDEWEB)

    Tahar, Malek Haj [Univ. of Grenoble (France)

    2016-08-07

    High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g., PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field imperfections on the

  1. Control of stripelike and hexagonal self-assembly of gold nanoparticles by the tuning of interactions between triphenylene ligands.

    Science.gov (United States)

    Shen, Zhongrong; Yamada, Mami; Miyake, Mikio

    2007-11-21

    We describe the self-assembly of gold nanoparticles (Au NPs) protected with newly synthesized discotic liquid crystalline molecules of hexaalkoxy-substituted triphenylene (TP) in mixed toluene/methanol solvent. The stripelike (i.e., 2D consisting of linear 1D in stripe) self-assembly is realized successfully by the aid of pi-pi stacking of TP ligand on Au NPs. The smaller Au NPs with TP (AuTP) or the longer alkyl chain between TP and the gold core provide more free spaces among TP moieties. These spaces allow easy insertion of TP on adjacent AuTPs to lead an interparticle pi-pi interaction to form the stripelike arrangement. The solvent hydrophilicity can also serve as a controlled index to tune arrangement among stripelike, hexagonal close packed (hcp), or disorder. We have changed the solvent hydrophilicity by changing the ratio of methanol to toluene, which affects the balance of solution of AuTP (in toluene) and deposition (in methanol). The larger space between TPs and appropriate solvent hydrophilicity realize stripelike self-assembly caused by a strong pi-pi interaction between TPs, which was characterized by TEM, as well as fluorescence, dynamic light scattering, and 1H NMR spectra.

  2. Solubility of Benzo[a]pyrene and Organic Matter of Soil in Subcritical Water

    Directory of Open Access Journals (Sweden)

    Svetlana Sushkova

    2015-12-01

    Full Text Available A dynamic subcritical water extraction method of benzo[a]pyrene from soils is under consideration. The optimum conditions for benzo[a]pyrene extraction from soil are described including the soil treatment by subcritical water at 250 °C and 100 atm for 30 min. The effectiveness of developed method was determined using the matrix spiking recovery technique. A comparative analysis was made to evaluate the results of benzo[a]pyrene extraction from soils using the subcritical water and organic solvents. The advantages of the subcritical water extraction involve the use of ecologically friendly solvent, a shorter time for the analysis and a higher amount of benzo[a]pyrene extracted from soil (96 %. The influence of subcritical water extraction on soil properties was measured the investigation of the processes occurring within soil under the influence the high temperature and pressure. Under appropriate conditions of the experiment there is the destruction of the soil organic matter while the composition of the soil mineral fraction remains practically unchanged.

  3. Subcritical water extraction of flavoring and phenolic compounds from cinnamon bark (Cinnamomum zeylanicum).

    Science.gov (United States)

    Khuwijitjaru, Pramote; Sayputikasikorn, Nucha; Samuhasaneetoo, Suched; Penroj, Parinda; Siriwongwilaichat, Prasong; Adachi, Shuji

    2012-01-01

    Cinnamon bark (Cinnamomum zeylanicum) powder was treated with subcritical water at 150 and 200°C in a semi-continuous system at a constant flow rate (3 mL/min) and pressure (6 MPa). Major flavoring compounds, i.e., cinnamaldehyde, cinnamic acid, cinnamyl alcohol and coumarin, were extracted at lower recoveries than the extraction using methanol, suggesting that degradation of these components might occur during the subcritical water treatment. Caffeic, ferulic, p-coumaric, protocatechuic and vanillic acids were identified from the subcritical water treatment. Extraction using subcritical water was more effective to obtain these acids than methanol (50% v/v) in both number of components and recovery, especially at 200°C. Subcritical water treatment at 200°C also resulted in a higher total phenolic content and DPPH radical scavenging activity than the methanol extraction. The DPPH radical scavenging activity and total phenolic content linearly correlated but the results suggested that the extraction at 200°C might result in other products that possessed a free radical scavenging activity other than the phenolic compounds.

  4. Effect of water on critical and subcritical fracture properties of Woodford shale

    Science.gov (United States)

    Chen, Xiaofeng; Eichhubl, Peter; Olson, Jon E.

    2017-04-01

    Subcritical fracture behavior of shales under aqueous conditions is poorly characterized despite increased relevance to oil and gas resource development and seal integrity in waste disposal and subsurface carbon sequestration. We measured subcritical fracture properties of Woodford shale in ambient air, dry CO2 gas, and deionized water by using the double-torsion method. Compared to tests in ambient air, the presence of water reduces fracture toughness by 50%, subcritical index by 77%, and shear modulus by 27% and increases inelastic deformation. Comparison between test specimens coated with a hydrophobic agent and uncoated specimens demonstrates that the interaction of water with the bulk rock results in the reduction of fracture toughness and enhanced plastic effects, while water-rock interaction limited to the vicinity of the propagating fracture tip by a hydrophobic specimen coating lowers subcritical index and increases fracture velocity. The observed deviation of a rate-dependent subcritical index from the power law K-V relations for coated specimens tested in water is attributed to a time-dependent weakening process resulting from the interaction between water and clays in the vicinity of the fracture tip.

  5. Concept of turbines for ultrasupercritical, supercritical, and subcritical steam conditions

    Science.gov (United States)

    Mikhailov, V. E.; Khomenok, L. A.; Pichugin, I. I.; Kovalev, I. A.; Bozhko, V. V.; Vladimirskii, O. A.; Zaitsev, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.

    2017-11-01

    The article describes the design features of condensing turbines for ultrasupercritical initial steam conditions (USSC) and large-capacity cogeneration turbines for super- and subcritical steam conditions having increased steam extractions for district heating purposes. For improving the efficiency and reliability indicators of USSC turbines, it is proposed to use forced cooling of the head high-temperature thermally stressed parts of the high- and intermediate-pressure rotors, reaction-type blades of the high-pressure cylinder (HPC) and at least the first stages of the intermediate-pressure cylinder (IPC), the double-wall HPC casing with narrow flanges of its horizontal joints, a rigid HPC rotor, an extended system of regenerative steam extractions without using extractions from the HPC flow path, and the low-pressure cylinder's inner casing moving in accordance with the IPC thermal expansions. For cogeneration turbines, it is proposed to shift the upper district heating extraction (or its significant part) to the feedwater pump turbine, which will make it possible to improve the turbine plant efficiency and arrange both district heating extractions in the IPC. In addition, in the case of using a disengaging coupling or precision conical bolts in the coupling, this solution will make it possible to disconnect the LPC in shifting the turbine to operate in the cogeneration mode. The article points out the need to intensify turbine development efforts with the use of modern methods for improving their efficiency and reliability involving, in particular, the use of relatively short 3D blades, last stages fitted with longer rotor blades, evaporation techniques for removing moisture in the last-stage diaphragm, and LPC rotor blades with radial grooves on their leading edges.

  6. Characterization of the Subcritical Water Extraction of Fluoxetine-Hydrochloride.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B; Lambertus, Gordon; Jensen, Eric

    2012-08-10

    The characteristics of using Subcritical Water Extraction (SWE) to recover Fluoxetine-Hydrochloride from both standard solutions and the contents of commercial capsule formulations were investigated. Analysis of solutions and extracts was done by HPLC with UV detection at 254 nm. Standard solutions of Fluoxetine-Hydrochloride were exposed to a variety of SWE operating conditions, including temperatures from 125 to 275°C and periods ranging from 5 to 30 min. Fluoxetine-Hydrochloride could be quantitatively recovered from standard solutions (1.0mg/mL) that were heated up to 175°C for 30 min, up to 200°C for 15 min, or up to 225°C for 10 min. At higher temperatures and/or times, Fluoxetine-Hydrochloride recoveries were generally incomplete and often produced decomposition by-products during the process. By comparison, the concentration of Fluoxetine-Hydrochloride in the standard solution had relatively little effect on recovery. Considering these parameters, an SWE method was developed to extract Fluoxetine-Hydrochloride from the contents of Prozac(®) capsules. It was found that Fluoxetine-Hydrochloride could be quantitatively extracted from the capsule contents in 8 min at a temperature of 200°C using 3.5 mL of water as the extraction solvent. Gelatinization of the starch excipient in the capsule contents was also observed to occur temporarily during the capsule extractions, before ultimately disappearing again. The period of this phenomenon was dependent on both temperature and sample size. The results indicate that SWE can be a very useful method for Fluoxetine-Hydrochloride extraction and suggest that it may be interesting to explore other pharmaceuticals using this method as well. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L. Seed at Subcritical Conditions with Statistical Analysis

    Directory of Open Access Journals (Sweden)

    N. I. Yusoff

    2017-01-01

    Full Text Available Roselle seeds are the waste product of roselle processing, but they are now labeled as a polyphenol source with great herbal quality. In this work, polyphenols were extracted using ethanol-water (70% (v/v in a closed vessel under microwave irradiation. The main objective was to determine the optimal parameters statistically. The influence of extraction time (4–10 min, microwave power (100–300 W, and solvent/solid ratio (25–100 mL/g was studied. The total phenolic and flavonoids content were determined using Folin-Ciocalteu and aluminum chloride methods, respectively. Without temperature control, the subcritical conditions could occur and the highest flavonoid content (14.4251 mg QE/g was achieved at 158°C and 16.4 bar. Although the optimum MAE conditions (10 min, 300 W, and 97.7178 mL/g resulted in the highest yield (65.0367% and phenolic content (18.2244 mg GAE/g, low flavonoids content (6.4524 mg QE/g was unexpectedly obtained due to degradation at 163°C.

  8. Broom-like and flower-like heterostructures of silver molybdate through pH controlled self assembly

    Science.gov (United States)

    Singh, D. P.; Sirota, B.; Talpatra, S.; Kohli, P.; Rebholz, C.; Aouadi, S. M.

    2012-03-01

    Silver molybdate microrods are self-assembled into micron sized, broom-like and flower-like structures. Our investigations indicate that through a simple hydrothermal process, large scale production of such structure is possible. Using ammonium molybdate and silver nitrate solutions as precursors, we were able to show that the self assembled architectures were dependent on the pH of the starting precursor material. To understand the formation and destructions of the flower-like morphology, a systematic broad range (from acidic to basic) of pH-controlled experiments were performed and its influence on the structure/microstructure of synthesized materials was investigated. Scanning electron microscopy studies revealed that the morphology and microstructure of the products varied significantly by changing pH values from 3 to 8 during mixing of the reactants. pH = 3 and 4 resulted in the self assembly of monoclinic Ag2(Mo2O7) microrods into broom-like structures, whereas pH = 5 resulted into the flower-like morphology of mixed phase of monoclinic and triclinic Ag2Mo2O7. We also found that increasing the pH after a certain threshold value (for example pH > 6) resulted in total collapse of the flower-like morphology. Further increase of the pH to 7 and 8 resulted, the formation of microparticles of Ag2MoO4. A tentative scheme based on the pH-driven evolution of the self-assembly has been given to explain the formation of the observed heterostructures. Preliminary electrical characterization of thin films of the flower-like structures rendered non-linear current-voltage (I-V) responses. We also observed a strong hysteresis in the I-V responses of the flower-like structures developed under high bias conditions.

  9. Persistence Length Control of the Polyelectrolyte Layer-by-Layer Self-Assembly on Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, S J; Artyukhin, A B; Wang, Y; Ju, J; Stroeve, P; Noy, A

    2005-04-30

    One-dimensional inorganic materials such as carbon nanotubes1 and semiconductor nanowires have been central to important advances in materials science in the last decade. Unique mechanical and electronic properties of these molecular-scale wires enabled a variety of applications ranging from novel composite materials, to electronic circuits, to new sensors. Often, these applications require non-covalent modification of carbon nanotubes with organic compounds, DNA and biomolecules, and polymers to change nanotube properties or to add new functionality. We recently demonstrated a versatile and flexible strategy for non-covalent modification of carbon nanotubes using layer-by-layer self-assembly of polyelectrolytes. Researchers used this technique extensively for modification of flat surfaces, micro-, and nano-particles; however, little is known about the mechanism and the factors influencing layer-by-layer self-assembly in one-dimensional nanostructures. The exact conformation of polyelectrolyte chains deposited on single-walled carbon nanotubes (SWNT) is still unknown. There are two possible configurations: flexible polymers wrapping around the nanotube and stretched, rigid chains stacked parallel to the nanotube axis. Several factors, such as polymer rigidity, surface curvature, and strength of polymer-surface interactions, can determine the nature of assembly. Persistence length of the polymer chain should be one of the critical parameters, since it determines the chain's ability to wrap around the nanotube. Indeed, computer simulations for spherical substrates show that polymer rigidity and substrate surface curvature can influence the deposition process. Computational models also show that the persistence length of the polymer must fall below the threshold values determined by target surface curvature in order to initiate polyelectrolyte deposition process. Although these models described the effects of salt concentration and target surface curvature, they

  10. Control of stilbene conformation and fluorescence in self-assembled capsules

    Science.gov (United States)

    Ams, Mark R; Ajami, Dariush; Craig, Stephen L; Yang, Jye-Shane

    2009-01-01

    Summary The extensively studied trans-stilbene molecule is known to give only weak fluorescence in solution and inside loosely-fitting synthetic capsules. However, trans-stilbene has been recently studied in the context of antibody interiors, where binding results in strong blue fluorescence. The present research was undertaken to understand the spatial factors that influence stilbene fluorescence. trans-Stilbene was encapsulated in the snug, self-assembled complex 1.1 and exhibited fluorescence quenching due to the distortion of its ground-state geometry. When the complex is elongated by incorporating glycouril spacers, trans-stilbene is allowed to adapt a fully coplanar arrangement and fluorescence returns. PMID:20300499

  11. Controlled in situ growth of tunable plasmonic self-assembled nanoparticle arrays.

    Science.gov (United States)

    Verre, R; Fleischer, K; McGilp, J F; Fox, D; Behan, G; Zhang, H; Shvets, I V

    2012-01-27

    Self-assembled silver nanoparticle (NP) arrays were produced by deposition at glancing angles on transparent stepped Al2O3 templates. The evolution of the plasmonic resonances has been monitored using reflection anisotropy spectroscopy (RAS) during growth. It is demonstrated that the morphology of the array can be tailored by changing the template structure, resulting in a large tunability of the optical resonances. In order to extract detailed information on the origin of the measured dichroic response of the system, a model based on dipolar interactions has been developed and the effect of tarnishing and morphological dispersion addressed.

  12. Mismatch discrimination of lipidated DNA and LNA-probes (LiNAs) in hybridization-controlled liposome assembly

    DEFF Research Database (Denmark)

    Jakobsen, Ulla; Vogel, Stefan

    2016-01-01

    Assays for mismatch discrimination and detection of single nucleotide variations by hybridization-controlled assembly of liposomes, which do not require tedious surface chemistry, are versatile for both DNA and RNA targets. We report herein a comprehensive study on different DNA and LNA (locked...... assay in the context of mismatch discrimination and SNP detection are presented. The advantages of membrane-anchored LiNA-probes compared to chemically attached probes on solid nanoparticles (e.g. gold nanoparticles) are described. Key functionalities such as non-covalent attachment of LiNA probes...

  13. YALINA facility a sub-critical Accelerator- Driven System (ADS) for nuclear energy research facility description and an overview of the research program (1997-2008).

    Energy Technology Data Exchange (ETDEWEB)

    Gohar, Y.; Smith, D. L.; Nuclear Engineering Division

    2010-04-28

    The YALINA facility is a zero-power, sub-critical assembly driven by a conventional neutron generator. It was conceived, constructed, and put into operation at the Radiation Physics and Chemistry Problems Institute of the National Academy of Sciences of Belarus located in Minsk-Sosny, Belarus. This facility was conceived for the purpose of investigating the static and dynamic neutronics properties of accelerator driven sub-critical systems, and to serve as a neutron source for investigating the properties of nuclear reactions, in particular transmutation reactions involving minor-actinide nuclei. This report provides a detailed description of this facility and documents the progress of research carried out there during a period of approximately a decade since the facility was conceived and built until the end of 2008. During its history of development and operation to date (1997-2008), the YALINA facility has hosted several foreign groups that worked with the resident staff as collaborators. The participation of Argonne National Laboratory in the YALINA research programs commenced in 2005. For obvious reasons, special emphasis is placed in this report on the work at YALINA facility that has involved Argonne's participation. Attention is given here to the experimental program at YALINA facility as well as to analytical investigations aimed at validating codes and computational procedures and at providing a better understanding of the physics and operational behavior of the YALINA facility in particular, and ADS systems in general, during the period 1997-2008.

  14. Control over nanostructures and associated mesomorphic properties of doped self-assembled triarylamine liquid crystals.

    Science.gov (United States)

    Domoto, Yuya; Busseron, Eric; Maaloum, Mounir; Moulin, Emilie; Giuseppone, Nicolas

    2015-01-26

    We have synthesized a series of triarylamine-cored molecules equipped with an adjacent amide moiety and dendritic peripheral tails in a variety of modes. We show by (1) H NMR and UV/Vis spectroscopy that their supramolecular self-assembly can be promoted in solution upon light stimulation and radical initiation. In addition, we have probed their molecular arrangements and mesomorphic properties in the bulk by integrated studies on their film state by using differential scanning calorimetry (DSC), variable-temperature polarizing optical microscopy (VT-POM), variable-temperature X-ray diffraction (VT-XRD), and atomic force microscopy (AFM). Differences in the number and the disposition of the peripheral tails significantly affect their mesomorphic properties associated with their lamellar- or columnar-packed nanostructures, which are based on segregated stacks of the triphenylamine cores and the lipophilic/lipophobic periphery. Such structural tuning is of interest for implementation of these soft self-assemblies as electroactive materials from solution to mesophases. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Subcritical measurements of the WINCO slab tank experiment using the source-jerk technique

    Energy Technology Data Exchange (ETDEWEB)

    Spriggs, G.D.; Hansen, G.E.; Martin, E.R.; Plassmann, E.A.; Pederson, R.A.; Schlesser, J.A.; Krawczyk, T.L.; Tanner, J.E.; Smolen, G.R. (Los Alamos National Lab., NM (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA); Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA))

    1989-01-01

    Subcritical measurements of the WINCO slab tank using the source-jerk technique are presented. This technique determines subcriticality by analyzing the transient response produced by the sudden removal of an extraneous neutron source (i.e., a source jerk). We have found that the technique can provide an accurate means of measuring k in configurations that are close to critical (i.e., 0.90 < k < 1.0). As the system becomes more subcritical (i.e., k < 0.90), spatial effects introduce significant biases depending on the source and detector positions. A comparison between the measurements and Monte Carlo code calculations is also presented. 15 refs., 6 figs., 2 tabs.

  16. Alpha Eigenvalue Estimation from Dynamic Monte Carlo Calculation for Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shaukat, Nadeem; Shim, Hyung Jin; Jang, Sang Hoon [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    The dynamic Monte Carlo (DMC) method has been used in the TART code for the α eigenvalue calculations. A unique method has been equipped to measure the α in time-stepwise Monte Carlo simulations. For off-critical systems, the neutron population is allowed to change exponentially over a period of time. The neutron population is uniformly combed to return it to the neutron population started with at the beginning of time boundary. In this study, the conventional dynamic Monte Carlo method has been implemented in the McCARD. There is an exponential change of neutron population at the end of each time boundary for off-critical systems. In order to control this exponential change at the end of each time boundary, a conventional time cut-off controlling population strategy is included in the DMC module implemented in the McCARD. the conventional combing method to control the neutron population for off-critical systems is implemented. Instead of considering the cycles, the simulation is divided in time intervals. At the end of each time interval, neutron population control is applied on the banked neutrons. Randomly selected neutrons are discarded, until the size of neutron population matches the initial neutron histories at the beginning of time simulation. The prompt neutron decay constant α is estimated from DMC algorithm for subcritical systems. The effectiveness of the results is examined for two-group infinite homogeneous problems with varying the k-value. From the comparisons with the analytical solutions, it is observed that the results are quite comparable with each other for each k-value.

  17. Subcritical calculation of the nuclear material warehouse;Calculo de subcriticidad del almacen del material nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Mazon R, R., E-mail: teodoro.garcia@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    In this work the subcritical calculation of the nuclear material warehouse of the Reactor TRIGA Mark III labyrinth in the Mexico Nuclear Center is presented. During the adaptation of the nuclear warehouse (vault I), the fuel was temporarily changed to the warehouse (vault II) and it was also carried out the subcritical calculation for this temporary arrangement. The code used for the calculation of the effective multiplication factor, it was the Monte Carlo N-Particle Extended code known as MCNPX, developed by the National Laboratory of Los Alamos, for the particles transport. (Author)

  18. Superphenylphosphines: Nanographene-based Ligands That Control Coordination Geometry and Drive Supramolecular Assembly.

    Science.gov (United States)

    Smith, Jordan Neale; Hook, James M; Lucas, Nigel T

    2017-12-18

    Tertiary phosphines remain widely utilized in synthesis, most notably as supporting ligands in metal complexes. A series of triarylphosphines bearing one to three hexa-peri-hexabenzocoronene (HBC) substituents has been prepared by an efficient divergent route. These "superphenylphosphines", P{HBC(t-Bu)5}nPh3-n (n = 1-3), form the palladium complexes Pd2Cl2L2 and Pd2Cl4L2 where the isomer distribution in solution is dependent on the number of HBC substituents. The crystalline structures of five complexes all show intramolecular π-stacking between HBC-phosphines to form a supramolecular bidentate-like ligand that distorts the metal coordination geometry. When n = 2 or 3, the additional HBC substituents engage in intermolecular π-stacking to assemble the complexes into continuous ribbons or sheets. The phosphines adopt HBC's characteristics including strong optical absorption, green emission, and redox activity.

  19. Directional cell movements downstream of Gbx2 and Otx2 control the assembly of sensory placodes

    Directory of Open Access Journals (Sweden)

    Ben Steventon

    2016-11-01

    Full Text Available Cranial placodes contribute to sensory structures including the inner ear, the lens and olfactory epithelium and the neurons of the cranial sensory ganglia. At neurula stages, placode precursors are interspersed in the ectoderm surrounding the anterior neural plate before segregating into distinct placodes by as yet unknown mechanisms. Here, we perform live imaging to follow placode progenitors as they aggregate to form the lens and otic placodes. We find that while placode progenitors move with the same speed as their non-placodal neighbours, they exhibit increased persistence and directionality and these properties are required to assemble morphological placodes. Furthermore, we demonstrate that these factors are components of the transcriptional networks that coordinate placode cell behaviour including their directional movements. Together with previous work, our results support a dual role for Otx and Gbx transcription factors in both the early patterning of the neural plate border and the later segregation of its derivatives into distinct placodes.

  20. Strain control in self assembled growth of vertical nano structured heteroepitaxial thin films

    Science.gov (United States)

    Tyagi, Shekhar; Sharma, Gaurav; Ganesan, V.; Sathe, V. G.

    2017-05-01

    Self-assembled rods of BaTiO3 are grown in the matrix of Y2O3 and MgO on (001) oriented LaAlO3 and MgO substrates, respectively, using pulsed laser deposition. X ray diffraction revealed the heteroepitaxy of the films and confirmed the phase purity of the two phases. Atomic force microscopy showed the growth to be columnar type and scanning electron microscopy confirmed the growth of the vertical Nano roads of one phase (BaTiO3) in the matrix of other phase. The BaTiO3 rods are free from substrate clamping effect and highly strained in out-of-plane direction.

  1. Morphology control of perovskite light-emitting diodes by using amino acid self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Nana; Cheng, Lu; Wang, Jianpu, E-mail: iamjpwang@njtech.edu.cn [Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials - SICAM, Nanjing Tech University - NanjingTech, 30 South Puzhu Road, Nanjing 211816 (China); Si, Junjie; Liang, Xiaoyong [State Key Laboratory of Silicon Materials, Center for Chemistry of High-Performance and Novel Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Jin, Yizheng [Center for Chemistry of High-Performance and Novel Materials, State Key Laboratory of Silicon Materials, and Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Huang, Wei [Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials - SICAM, Nanjing Tech University - NanjingTech, 30 South Puzhu Road, Nanjing 211816 (China); Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023 (China)

    2016-04-04

    Amino acid self-assembled monolayers are used in the fabrication of light-emitting diodes based on organic-inorganic halide perovskites. The monolayers of amino acids provide modified interfaces by anchoring to the surfaces of ZnO charge-transporting layers using carboxyl groups, leaving the amino groups to facilitate the nucleation of MAPbBr{sub 3} perovskite films. This surface-modification strategy, together with chlorobenzene-assisted fast crystallization method, results in good surface coverage and reduced defect density of the perovskite films. These efforts lead to green perovskite light emitting diodes with a low turn-on voltage of 2 V and an external quantum efficiency of 0.43% at a brightness of ∼5000 cd m{sup −2}.

  2. High Performance Platinum Group Metal Free Membrane Electrode Assemblies through Control of Interfacial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Ayers, Katherine [Proton Energy Systems, Wallingford, CT (United States); Capuano, Christopher [Proton Energy Systems, Wallingford, CT (United States); Atanassov, Plamen [Univ. of New Mexico, Albuquerque, NM (United States); Mukerjee, Sanjeev [Northeastern Univ., Boston, MA (United States); Hickner, Michael [Pennsylvania State Univ., University Park, PA (United States)

    2017-11-29

    The quantitative goal of this project was to produce a high-performance anion exchange membrane water electrolyzer (AEM-WE) completely free of platinum group metals (PGMs), which could operate for at least 500 hours with less than 50 microV/hour degradation, at 500 mA/cm2. To achieve this goal, work focused on the optimization of electrocatalyst conductivity, with dispersion and utilization in the membrane electrode assembly (MEA) improved through refinement of deposition techniques. Critical factors were also explored with significant work undertaken by Northeastern University to further understand catalyst-membrane-ionomer interfaces and how they differ from liquid electrolyte. Water management and optimal cell operational parameters were established through the design, fabrication, and test of a new test station at Proton specific for AEM evaluation. Additionally, AEM material stability and robustness at high potentials and gas evolution conditions were advanced at Penn State.

  3. Controlling the optical parameters of self-assembled silver films with wetting layers and annealing

    Science.gov (United States)

    Ciesielski, Arkadiusz; Skowronski, Lukasz; Trzcinski, Marek; Szoplik, Tomasz

    2017-11-01

    We investigated the influence of presence of Ni and Ge wetting layers as well as annealing on the permittivity of Ag films with thicknesses of 20, 35 and 65 nm. Most of the research on thin silver films deals with very small (atomic force microscopy, ellipsometric and X-ray photoelectron spectroscopy measurements, shows that utilizing a wetting layer is comparable to increasing the thickness of the silver film. Both operations decrease the roughness-to-thickness ratio, thus decreasing the scattering losses and both narrow the Lorentz-shaped interband transition peak. However, while increasing silver thickness increases absorption on the free carriers, the use of wetting layers influences the self-assembled internal structure of silver films in such a way, that the free carrier absorption decreases. Wetting layers also introduce additional contributions from effects like segregation or diffusion, which evolve in time and due to annealing.

  4. High-current cyclotron to drive an electronuclear assembly

    CERN Document Server

    Alenitsky, Yu G

    2002-01-01

    The proposal on creation of a high-current cyclotron complex for driving an electronuclear assembly reported at the 17th Meeting on Accelerators of Charged Particles is discussed. Some changes in the basic design parameters of the accelerator are considered in view of new results obtained in the recent works. It is shown that the cyclotron complex is now the most real and cheapest accelerator for production of proton beams with a power of up to 10 MW. Projects on design of a high-current cyclotron complex for driving an electronuclear subcritical assembly are presented.

  5. Controlled Assembly of Heterobinuclear Sites on Mesoporous Silica: Visible Light Charge-Transfer Units with Selectable Redox Properties

    Energy Technology Data Exchange (ETDEWEB)

    Frei, Heinz; Han, Hongxian; Frei, Heinz

    2008-06-04

    Mild synthetic methods are demonstrated for the selective assembly of oxo-bridged heterobinuclear units of the type TiOCrIII, TiOCoII, and TiOCeIII on mesoporous silica support MCM-41. One method takes advantage of the higher acidity and, hence, higher reactivity of titanol compared to silanol OH groups towards CeIII or CoII precursor. The procedure avoids the customary use of strong base. The controlled assembly of the TiOCr system exploits the selective redox reactivity of one metal towards another (TiIII precursor reacting with anchored CrVI centers). The observed selectivity for linking a metal precursor to an already anchored partner versus formation of isolated centers ranges from a factor of six (TiOCe) to complete (TiOCr, TiOCo). Evidence for oxo bridges and determination of the coordination environment of each metal centers is based on K-edge EXAFS (TiOCr), L-edge absorption spectroscopy (Ce), and XANES measurements (Co, Cr). EPR, optical, FT-Raman and FT-IR spectroscopy furnish additional details on oxidation state and coordination environment of donor and acceptor metal centers. In the case of TiOCr, the integrity of the anchored group upon calcination (350 oC) and cycling of the Cr oxidation state is demonstrated. The binuclear units possess metal-to-metal charge-transfer transitions that absorb deep in the visible region. The flexible synthetic method for assembling the units opens up the use of visible light charge transfer pumps featuring donor or acceptor metals with selectable redox potential.

  6. Solution-Assembled Blends of Regioregularity-Controlled Polythiophenes for Coexistence of Mechanical Resilience and Electronic Performance.

    Science.gov (United States)

    Kim, Hyeong Jun; Lee, Moo Yeol; Kim, Jin-Seong; Kim, Jae-Han; Yu, Hojeong; Yun, Hongseok; Liao, Kin; Kim, Taek-Soo; Oh, Joon Hak; Kim, Bumjoon J

    2017-04-26

    Considering all the potential applications of organic electronics in portable, wearable, and implantable devices, it is of great importance to develop electroactive materials that possess mechanical reliability along with excellent electronic performance. The coexistence of these two attributes, however, is very difficult to achieve because there is an inverse relationship between the electrical properties and the mechanical flexibility, both of which are associated with the conjugation length and intermolecular ordering of the polymers. Herein, we demonstrate a simple and robust approach based on solution assembly of two different poly(3-hexylthiophene)s (P3HTs) with regioregularity (RR) contents of 97% and 66% to impart both electrical and mechanical properties to films for organic electronic applications. The 97% RR P3HT exhibits high electronic performance but poor mechanical resilience, and vice versa for the 66% RR P3HT. Selective crystallization of high RR P3HT induced by solution assembly allows the use of a one-step process to construct percolated networks of high RR P3HT nanowires (NWs) in a low RR P3HT matrix. Only 5 wt % of high RR P3HT NWs in a 95 wt % low RR P3HT matrix was required to produce hole mobilities comparable to that of pure high RR P3HT, and this blend film exhibited improvements by factors of 20 and 60 in elongation at break and toughness, respectively. Selective self-assembly of RR-controlled polymers allowed us to overcome the fragile nature of highly crystalline conjugated polymer films without sacrificing their electronic properties.

  7. Automatic micropart assembly of 3-Dimensional structure by vision based control

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lidai [University of Toronto, Toronto (Canada); Kim, Seung Min [Korean Intellectual Property Office, Daejeon (Korea, Republic of)

    2008-12-15

    We propose a vision control strategy to perform automatic microassembly tasks in three-dimension (3-D) and develop relevant control software: specifically, using a 6 degree-of-freedom (DOF) robotic workstation to control a passive microgripper to automatically grasp a designated micropart from the chip, pivot the micropart, and then move the micropart to be vertically inserted into a designated slot on the chip. In the proposed control strategy, the whole microassembly task is divided into two subtasks, micro-grasping and micro-joining, in sequence. To guarantee the success of microassembly and manipulation accuracy, two different two-stage feedback motion strategies, the pattern matching and auto-focus method are employed, with the use of vision-based control system and the vision control software developed. Experiments conducted demonstrate the efficiency and validity of the proposed control strategy

  8. Designing a mini subcritical nuclear reactor; Diseno de un mini reactor nuclear subcritico

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo G, C. R.; Vega C, H. R.; Davila H, V. M., E-mail: rafelaescobedo@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Jardin Juarez 147, Col. Centro, 98000 Zacatecas, Zac. (Mexico)

    2015-10-15

    In this work the design of a mini subcritical nuclear reactor formed by means of light water moderator, uranium as fuel, and isotopic neutron source of {sup 239}PuBe was carried out. The design was done by Monte Carlo methods with the code MCNP5 in which uranium was modeled in an array of concentric holes cylinders of 8.5, 14.5, 20.5, 26.5, 32.5 cm of internal radius and 3 cm of thickness, 36 cm of height. Different models were made from a single fuel cylinder (natural uranium) to five. The neutron source of {sup 239}PuBe was situated in the center of the mini reactor; in each arrangement was used water as moderator. Cross sections libraries Endf/Vi were used and the number of stories was large enough to ensure less uncertainty than 3%. For each case the effective multiplication factor k{sub e}-f{sub f}, the amplification factor and the power was calculated. Outside the mini reactor the ambient dose equivalent H (10) was calculated for different cases. The value of k{sub eff}, the amplification factor and power are directly related to the number of cylinders of uranium as fuel. Although the average energy of the neutrons {sup 239}PuBe is between 4.5 and 5 MeV in the case of the mini reactor for a cylinder, in the neutron spectrum the presence of thermal neutrons does not exist, so that produced fissions are generated with fast neutrons, and in designs of two and three rings the neutron spectra shows the presence of thermal neutrons, however the fissions are being generated with fast neutrons. Finally in the four and five cases the amount of moderator is enough to thermalized the neutrons and thereby produce the fission. The maximum value for k{sub eff} was 0.82; this value is very close to the assembly of Universidad Autonoma de Zacatecas generating a k{sub eff} of 0.86. According to the safety and radiation protection standards for the design of mini reactor of one, two and three cylinders they comply with the established safety, while designs of four and five

  9. Munc18-1 Controls SNARE Protein Complex Assembly during Human Sperm Acrosomal Exocytosis*

    Science.gov (United States)

    Rodríguez, Facundo; Zanetti, M. Natalia; Mayorga, Luis S.; Tomes, Claudia N.

    2012-01-01

    The spermatozoon is a very specialized cell capable of carrying out a limited set of functions with high efficiency. Sperm are then excellent model cells to dissect fundamental processes such as regulated exocytosis. The secretion of the single dense-core granule of mammalian spermatozoa relies on the same highly conserved molecules and goes through the same stages as exocytosis in other types of cells. In this study, we describe the presence of Munc18-1 in human sperm and show that this protein has an essential role in acrosomal exocytosis. We observed that inactivation of endogenous Munc18-1 with a specific antibody precluded the stabilization of trans-SNARE complexes and inhibited acrosomal exocytosis. Addition of recombinant Munc18-1 blocked secretion by sequestering monomeric syntaxin, an effect that was rescued by α-soluble NSF attachment protein. By electron microscopy, we observed that both the anti-Munc18-1 antibody and recombinant Munc18-1 inhibited the docking of the acrosome to the plasma membrane. In conclusion, our results indicate that Munc18-1 plays a key role in the dynamics of trans-SNARE complex assembly and/or stabilization, a process that is necessary for the docking of the outer acrosomal membrane to the plasma membrane and subsequent fusion pore opening. PMID:23091057

  10. Clathrin assembly protein AP180 and CALM differentially control axogenesis and dendrite outgrowth in embryonic hippocampal neurons.

    Science.gov (United States)

    Bushlin, Ittai; Petralia, Ronald S; Wu, Fangbai; Harel, Asaff; Mughal, Mohamed R; Mattson, Mark P; Yao, Pamela J

    2008-10-08

    Emerging data suggest that, much like epithelial cells, the polarized growth of neurons requires both the secretory and endocytic pathways. The clathrin assembly proteins AP180 and CALM (clathrin assembly lymphoid myeloid protein) are known to be involved in clathrin-mediated endocytosis, but their roles in mammalian neurons and, in particular, in developmental processes before synaptogenesis are unknown. Here we provide evidence that AP180 and CALM play critical roles in establishing the polarity and controlling the growth of axons and dendrites in embryonic hippocampal neurons. Knockdown of AP180 primarily impairs axonal development, whereas reducing CALM levels results in dendritic dystrophy. Conversely, neurons that overexpress AP180 or CALM generate multiple axons. Ultrastructural analysis shows that CALM affiliates with a wider range of intracellular trafficking organelles than does AP180. Functional analysis shows that endocytosis is reduced in both AP180-deficient and CALM-deficient neurons. Additionally, CALM-deficient neurons show disrupted secretory transport. Our data demonstrate previously unknown functions for AP180 and CALM in intracellular trafficking that are essential in the growth of neurons.

  11. Fluorescent polymeric assemblies as stimuli-responsive vehicles for drug controlled release and cell/tissue imaging.

    Science.gov (United States)

    Chang, Ying; Li, Yang; Yu, Shirong; Mao, Jie; Liu, Cheng; Li, Qi; Yuan, Conghui; He, Ning; Luo, Weiang; Dai, Lizong

    2015-01-16

    Polymer assemblies with good biocompatibility, stimuli-responsive properties and clinical imaging capability are desirable carriers for future biomedical applications. Herein, we report on the synthesis of a novel anthracenecarboxaldehyde-decorated poly(N-(4-aminophenyl) methacryl amide-oligoethyleneglycolmonomethylether methacrylate) (P(MAAPAC-MAAP-MAPEG)) copolymer, comprising fluorescent chromophore and acid-labile moiety. This copolymer can assemble into micelles in aqueous solution and shows a spherical shape with well-defined particle size and narrow particle size distribution. The pH-responsive property of the micelles has been evaluated by the change of particle size and the controlled release of guest molecules. The intrinsic fluorescence property endows the micelles with excellent cell/tissue imaging capability. Cell viability evaluation with human hepatocellular carcinoma BEL-7402 cells demonstrates that the micelles are nontoxic. The cellular uptake of the micelles indicates a time-dependent behavior. The H22-tumor bearing mice treated with the micelles clearly exhibits the tumor accumulation. These multi-functional nanocarriers may be of great interest in the application of drug delivery.

  12. Laser Ultrasonic System for Surface Crack Visualization in Dissimilar Welds of Control Rod Drive Mechanism Assembly of Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Yun-Shil Choi

    2014-01-01

    Full Text Available In this paper, we propose a J-groove dissimilar weld crack visualization system based on ultrasonic propagation imaging (UPI technology. A full-scale control rod drive mechanism (CRDM assembly specimen was fabricated to verify the proposed system. An ultrasonic sensor was contacted at one point of the inner surface of the reactor vessel head part of the CRDM assembly. Q-switched laser beams were scanned to generate ultrasonic waves around the weld bead. The localization and sizing of the crack were possible by ultrasonic wave propagation imaging. Furthermore, ultrasonic spectral imaging unveiled frequency components of damage-induced waves, while wavelet-transformed ultrasonic propagation imaging enhanced damage visibility by generating a wave propagation video focused on the frequency component of the damage-induced waves. Dual-directional anomalous wave propagation imaging with adjacent wave subtraction was also developed to enhance the crack visibility regardless of crack orientation and wave propagation direction. In conclusion, the full-scale specimen test demonstrated that the multiple damage visualization tools are very effective in the visualization of J-groove dissimilar weld cracks.

  13. Modeling and characterization of molecular structures in self assembled and Langmuir-Blodgett films for controlled fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Cesarano, J. III [Sandia National Labs., Albuquerque, NM (United States). Materials and Process Sciences Center

    1997-10-01

    Self Assembled (SA) thin films and Langmuir-Blodgett (LB) thin films are emerging technologies for the development of chemical and bio-chemical sensors, electrooptic films, second harmonic generators (frequency doublers), templates for biomimetic growth etc. One of the goals of this project was to extend Sandia`s characterization techniques and molecular modeling capabilities for these complex two-dimensional geometries with the objective of improving the control of the fabrication of these structures for specific applications. Achieving this requires understanding both the structure throughout the thickness of the films and the in-plane lattice of the amphiphilic molecules. To meet these objectives they used atomic force microscopy (AFM), X-ray reflectivity, and molecular modeling. While developing these capabilities, three different materials systems were fabricated and characterized: (1) Self Assembled Monolayers (SAMs) of octadecyltrichlorosilane (OTS) and LB films of arachidic acid on silicon wafers; (2) SAMs on PZT substrates; and (3) electrochemical deposition of CdS on LB film templates.

  14. Control of drug release through the in situ assembly of stimuli-responsive ordered mesoporous silica with magnetic particles.

    Science.gov (United States)

    Zhu, Shenmin; Zhou, Zhengyang; Zhang, Di

    2007-12-03

    A site-selective controlled delivery system for controlled drug release is fabricated through the in situ assembly of stimuli-responsive ordered SBA-15 and magnetic particles. This approach is based on the formation of ordered mesoporous silica with magnetic particles formed from Fe(CO)5 via the surfactant-template sol-gel method and control of transport through polymerization of N-isopropyl acrylamide inside the pores. Hydrophobic Fe(CO)5 acts as a swelling agent as well as being the source of the magnetic particles. The obtained system demonstrates a high pore diameter (7.1 nm) and pore volume (0.41 cm(3) g(-1)), which improves drug storage for relatively large molecules. Controlled drug release through the porous network is demonstrated by measuring the uptake and release of ibuprofen (IBU). The delivery system displays a high IBU storage capacity of 71.5 wt %, which is almost twice as large as the highest value based on SBA-15 ever reported. In vitro testing of IBU loading and release exhibits a pronounced transition at around 32 degrees C, indicating a typical thermosensitive controlled release.

  15. Electrokinetic Stringency Control in Self-Assembled Monolayer-based Biosensors for Multiplex Urinary Tract Infection Diagnosis

    Science.gov (United States)

    Liu, Tingting; Sin, Mandy L. Y.; Pyne, Jeff D.; Gau, Vincent; Liao, Joseph C.; Wong, Pak Kin

    2013-01-01

    Rapid detection of bacterial pathogens is critical toward judicious management of infectious diseases. Herein, we demonstrate an in situ electrokinetic stringency control approach for a self-assembled monolayer-based electrochemical biosensor toward urinary tract infection diagnosis. The in situ electrokinetic stringency control technique generates Joule heating induced temperature rise and electrothermal fluid motion directly on the sensor to improve its performance for detecting bacterial 16S rRNA, a phylogenetic biomarker. The dependence of the hybridization efficiency reveals that in situ electrokinetic stringency control is capable of discriminating single-base mismatches. With electrokinetic stringency control, the background noise due to the matrix effects of clinical urine samples can be reduced by 60%. The applicability of the system is demonstrated by multiplex detection of three uropathogenic clinical isolates with similar 16S rRNA sequences. The results demonstrate that electrokinetic stringency control can significantly improve the signal-to-noise ratio of the biosensor for multiplex urinary tract infection diagnosis. PMID:23891989

  16. Nonlinear dynamics aspects of subcritical transitions and singular flows in viscoelastic fluids

    NARCIS (Netherlands)

    Becherer, Paul

    2008-01-01

    Recently, there has been a renewed interest in theoretical aspects of flows of viscoelastic fluids (such as dilute polymer solutions). This thesis addresses two distinct issues related to such flows. Motivated by the possible occurrence of subcritical (finite-amplitude) instabilities in parallel

  17. Subcritical water - a perspective reaction media for biomass processing to chemicals

    OpenAIRE

    Pavlovič, Irena; Škerget, Mojca; Knez, Željko

    2015-01-01

    Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP

  18. Promotion or suppression of glucose isomerization in subcritical aqueous straight- and branched-chain alcohols.

    Science.gov (United States)

    Gao, Da-Ming; Kobayashi, Takashi; Adachi, Shuji

    2015-01-01

    The influence of water-miscible alcohols (methanol, 1-propanol, 2-propanol, and t-butyl alcohol) on the isomerization of glucose to fructose and mannose was investigated under subcritical aqueous conditions (180-200 °C). Primary and secondary alcohols promoted the conversion and isomerization of glucose to afford fructose and mannose with high and low selectivity, respectively. On the other hand, the decomposition (side-reaction) of glucose was suppressed in the presence of the primary and secondary alcohols compared with that in subcritical water. The yield of fructose increased with increasing concentration of the primary and secondary alcohols, and the species of the primary and secondary alcohols tested had little effect on the isomerization behavior of glucose. In contrast, the isomerization of glucose was suppressed in subcritical aqueous t-butyl alcohol. Both the conversion of glucose and the yield of fructose decreased with increasing concentration of t-butyl alcohol. In addition, mannose was not detected in reactions using subcritical aqueous t-butyl alcohol.

  19. Subcritical localization in the discrete nonlinear Schrödinger equation with arbitrary power nonlinearity

    DEFF Research Database (Denmark)

    Bang, O.; Juul Rasmussen, J.; Christiansen, P.L.

    1994-01-01

    Discretizing the continuous nonlinear Schrodinger equation with arbitrary power nonlinearity influences the time evolution of its ground state solitary solution. In the subcritical case, for grid resolutions above a certain transition value, depending on the degree of nonlinearity, the solution w...

  20. Subcritical crack growth behavior of AI2O3-Glass dental composites

    NARCIS (Netherlands)

    Zhu, Q.; With, G. de; Dortmans, L.J.M.G.; Feenstra, F.

    2003-01-01

    The purpose of this study is to investigate the subcritical crack growth (SCG) behavior of alumina-glass dental composites. Alumina-glass composites were fabricated by infiltrating molten glass to porous alumina preforms. Rectangular bars of the composite were subject to dynamic loading in air, with

  1. Controlled hydrophobic functionalization of natural fibers through self-assembly of amphiphilic diblock copolymer micelles.

    Science.gov (United States)

    Aarne, Niko; Laine, Janne; Hänninen, Tuomas; Rantanen, Ville; Seitsonen, Jani; Ruokolainen, Janne; Kontturi, Eero

    2013-07-01

    The functionalization of natural fibers is an important task that has recently received considerable attention. We investigated the formation of a hydrophobic layer from amphiphilic diblock copolymer micelles [polystyrene-block-poly(N-methyl-4-vinyl pyridinium iodide)] on natural fibers and on a model surface (mica). A series of micelles were prepared. The micelles were characterized by using cryoscopic TEM and light scattering, and their hydrophobization capability was studied through contact angle measurements, water adsorption, and Raman imaging. Mild heat treatment (130 °C) was used to increase the hydrophobization capability of the micelles. The results showed that the micelles could not hydrophobize a model surface, but could render the natural fibers water repellent both with and without heat treatment. This effect was systematically studied by varying the composition of the constituent blocks. The results showed that the micelle size (and the molecular weight of the constituent diblock copolymers) was the most important parameter, whereas the cationic (hydrophilic) part played only a minor role. We hypothesized that the hydrophobization effect could be attributed to a combination of the micelle size and the shrinkage of the natural fibers upon drying. The shrinking caused the roughness to increase on the fiber surface, which resulted in a rearrangement of the self- assembled layer in the wet state. Consequently, the fibers became hydrophobic through the roughness effects at multiple length scales. Mild heat treatment melted the micelle core and decreased the minimum size necessary for hydrophobization. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Assembly Domain-Based Optogenetic System for the Efficient Control of Cellular Signaling.

    Science.gov (United States)

    Furuya, Akihiro; Kawano, Fuun; Nakajima, Takahiro; Ueda, Yoshibumi; Sato, Moritoshi

    2017-06-16

    We previously developed the Magnet system, which consists of two distinct Vivid protein variants, one positively and one negatively charged, designated the positive Magnet (pMag) and negative Magnet (nMag), respectively. These two proteins bind to each other through electrostatic interactions, preventing unwanted homodimerization and providing selective light-induced heterodimerization. The Magnet system enables the manipulation of cellular functions such as protein-protein interactions and genome editing, although the system could be improved further. To enhance the ability of pMagFast2 (a pMag variant with fast kinetics) to bind nMag, we introduced several pMagFast2 modules in tandem into a single construct, pMagFast2(3×). However, the expression level of this construct decreased drastically with increasing number of pMagFast2 molecules integrated into a single construct. In the present study, we applied a new approach to improve the Magnet system based on an assembly domain (AD). Among several ADs, the Ca2+/calmodulin-dependent protein kinase IIα association domain (CAD) most enhanced the Magnet system. The present CAD-Magnet system overcame a trade-off issue between the expression level and binding affinity. The CAD-converged 12 pMag photoswitches exhibited a stronger interaction with nMag after blue light irradiation compared with monomeric pMag. Additionally, the CAD played a key role in converging effector proteins as well in a single complex. Owing to these substantial improvements, the CAD-Magnet system combined with Tiam1 allowed us to robustly induce localized formation of vertical ruffles on the apical plasma membrane. The CAD-Magnet system combined with 4D imaging was instrumental in revealing the dynamics of ruffle formation.

  3. Femtosecond laser-controlled self-assembly of amorphous-crystalline nanogratings in silicon.

    Science.gov (United States)

    Puerto, Daniel; Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

    2016-07-01

    Self-assembly (SA) of molecular units to form regular, periodic extended structures is a powerful bottom-up technique for nanopatterning, inspired by nature. SA can be triggered in all classes of solid materials, for instance, by femtosecond laser pulses leading to the formation of laser-induced periodic surface structures (LIPSS) with a period slightly shorter than the laser wavelength. This approach, though, typically involves considerable material ablation, which leads to an unwanted increase of the surface roughness. We present a new strategy to fabricate high-precision nanograting structures in silicon, consisting of alternating amorphous and crystalline lines, with almost no material removal. The strategy can be applied to static irradiation experiments and can be extended into one and two dimensions by scanning the laser beam over the sample surface. We demonstrate that lines and areas with parallel nanofringe patterns can be written by an adequate choice of spot size, repetition rate and scan velocity, keeping a constant effective pulse number (N eff) per area for a given laser wavelength. A deviation from this pulse number leads either to inhomogeneous or ablative structures. Furthermore, we demonstrate that this approach can be used with different laser systems having widely different wavelengths (1030 nm, 800 nm, 400 nm), pulse durations (370 fs, 100 fs) and repetition rates (500 kHz, 100 Hz, single pulse) and that the grating period can also be tuned by changing the angle of laser beam incidence. The grating structures can be erased by irradiation with a single nanosecond laser pulse, triggering recrystallization of the amorphous stripes. Given the large differences in electrical conductivity between the two phases, our structures could find new applications in nanoelectronics.

  4. Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes; Zhang, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Criticality Safety Division

    2016-09-27

    Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM_Solver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) “Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.”). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the keff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

  5. The cooling control system for focal plane assembly of astronomical satellite camera based on TEC

    Science.gov (United States)

    He, Yuqing; Du, Yunfei; Gao, Wei; Li, Baopeng; Fan, Xuewu; Yang, Wengang

    2017-02-01

    The dark current noise existing in the CCD of the astronomical observation camera has a serious influence on its working performance, reducing the working temperature of CCD can suppress the influence of dark current effectively. By analyzing the relationship between the CCD chip and the dark current noise, the optimum working temperature of the red band CCD focal plane is identified as -75°. According to the refrigeration temperature, a cooling control system for focal plane based on a thermoelectric cooler (TEC) was designed. It is required that the system can achieve high precision temperature control for the target. In the cooling control system, the 80C32 microcontroller was used as its systematic core processor. The advanced PID control algorithm is adopted to control the temperature of the top end of TEC. The bottom end of the TEC setting a constant value according to the target temperature used to assist the upper TEC to control the temperature. The experimental results show that the cooling system satisfies the requirements of the focal plane for the astronomical observation camera, it can reach the working temperature of -75° and the accuracy of ±2°.

  6. Model-Based Control of a Continuous Coating Line for Proton Exchange Membrane Fuel Cell Electrode Assembly

    Directory of Open Access Journals (Sweden)

    Vikram Devaraj

    2015-01-01

    Full Text Available The most expensive component of a fuel cell is the membrane electrode assembly (MEA, which consists of an ionomer membrane coated with catalyst material. Best-performing MEAs are currently fabricated by depositing and drying liquid catalyst ink on the membrane; however, this process is limited to individual preparation by hand due to the membrane’s rapid water absorption that leads to shape deformation and coating defects. A continuous coating line can reduce the cost and time needed to fabricate the MEA, incentivizing the commercialization and widespread adoption of fuel cells. A pilot-scale membrane coating line was designed for such a task and is described in this paper. Accurate process control is necessary to prevent manufacturing defects from occurring in the coating line. A linear-quadratic-Gaussian (LQG controller was developed based on a physics-based model of the coating process to optimally control the temperature and humidity of the drying zones. The process controller was implemented in the pilot-scale coating line proving effective in preventing defects.

  7. Cytoskeletal filament assembly and the control of cell spreading and function by extracellular matrix

    Science.gov (United States)

    Mooney, D. J.; Langer, R.; Ingber, D. E.

    1995-01-01

    This study was undertaken to analyze how cell binding to extracellular matrix produces changes in cell shape. We focused on the initial process of cell spreading that follows cell attachment to matrix and, thus, cell 'shape' changes are defined here in terms of alterations in projected cell areas, as determined by computerized image analysis. Cell spreading kinetics and changes in microtubule and actin microfilament mass were simultaneously quantitated in hepatocytes plated on different extracellular matrix substrata. The initial rate of cell spreading was highly dependent on the matrix coating density and decreased from 740 microns 2/h to 50 microns 2/h as the coating density was lowered from 1000 to 1 ng/cm2. At approximately 4 to 6 hours after plating, this initial rapid spreading rate slowed and became independent of the matrix density regardless of whether laminin, fibronectin, type I collagen or type IV collagen was used for cell attachment. Analysis of F-actin mass revealed that cell adhesion to extracellular matrix resulted in a 20-fold increase in polymerized actin within 30 minutes after plating, before any significant change in cell shape was observed. This was followed by a phase of actin microfilament disassembly which correlated with the most rapid phase of cell extension and ended at about 6 hours; F-actin mass remained relatively constant during the slow matrix-independent spreading phase. Microtubule mass increased more slowly in spreading cells, peaking at 4 hours, the time at which the transition between rapid and slow spreading rates was observed. However, inhibition of this early rise in microtubule mass using either nocodazole or cycloheximide did not prevent this transition. Use of cytochalasin D revealed that microfilament integrity was absolutely required for hepatocyte spreading whereas interference with microtubule assembly (using nocodazole or taxol) or protein synthesis (using cycloheximide) only partially suppressed cell extension. In

  8. Controlling nanomaterial synthesis, chemical reactions and self assembly in dynamic thin films.

    Science.gov (United States)

    Chen, Xianjue; Smith, Nicole M; Iyer, K Swaminathan; Raston, Colin L

    2014-03-07

    Recent advances in continuous-flow processors, which integrate sustainability metrics including scalability, have established their utility in materials and chemical processing. In this review the spinning disc processor (SDP) and the related rotating tube processor (RTP), are highlighted in the use of highly sheared and micro-mixed dynamic thin films in gaining control over such processing for a wide range of applications. Both SDP and RTP have a number of control parameters beyond traditional batch processing which are effective in (i) manipulating the size, shape, defects, agglomeration, and precipitation of nanoparticles, as well as decorating preformed nano-structures, for a variety of inorganic and organic compounds, (ii) controlling chemical reactivity and selectivity including the formation of polymers, and (iii) disassembling self organised nano-structures, as a tool for probing macromolecular structure under shear conditions.

  9. Robust Self-Assembly of Highly Ordered Complex Structures by Controlled Evaporation of Confined Microfluids

    Science.gov (United States)

    Lin, Zhiqun; Byun, Myunghwan; Hong, Suck Won

    2009-03-01

    We demonstrate a robust, one-step method of evaporating polymer solutions in curve-on-flat geometries to create versatile, highly regular microstructures in a precisely controlled environment, as well as offering a comprehensive study of the influence of different upper surfaces on complex structure formation via controlled evaporation. Our method further enhances current fabrication approaches to creating highly ordered structures in a simple and cost-effective manner, with the potential to be tailored for use in photonics, electronics, optoelectronics, microfluidic devices, nanotechnology, and biotechnology.

  10. Conceptual design of minor actinides burner with an accelerator-driven subcritical system.

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y.; Gohar, Y. (Nuclear Engineering Division)

    2011-11-04

    In the environmental impact study of the Yucca Mountain nuclear waste repository, the limit of spent nuclear fuel (SNF) for disposal is assessed at 70,000 metric tons of heavy metal (MTHM), among which 63,000 MTHM are the projected SNF discharge from U.S. commercial nuclear power plants though 2011. Within the 70,000 MTHM of SNF in storage, approximately 115 tons would be minor actinides (MAs) and 585 tons would be plutonium. This study describes the conceptual design of an accelerator-driven subcritical (ADS) system intended to utilize (burn) the 115 tons of MAs. The ADS system consists of a subcritical fission blanket where the MAs fuel will be burned, a spallation neutron source to drive the fission blanket, and a radiation shield to reduce the radiation dose to an acceptable level. The spallation neutrons are generated from the interaction of a 1 GeV proton beam with a lead-bismuth eutectic (LBE) or liquid lead target. In this concept, the fission blanket consists of a liquid mobile fuel and the fuel carrier can be LBE, liquid lead, or molten salt. The actinide fuel materials are dissolved, mixed, or suspended in the liquid fuel carrier. Therefore, fresh fuel can be fed into the fission blanket to adjust its reactivity and to control system power during operation. Monte Carlo analyses were performed to determine the overall parameters of an ADS system utilizing LBE as an example. Steady-state Monte Carlo simulations were studied for three fission blanket configurations that are similar except that the loaded amount of actinide fuel in the LBE is either 5, 7, or 10% of the total volume of the blanket, respectively. The neutron multiplication factor values of the three configurations are all approximately 0.98 and the MA initial inventories are each approximately 10 tons. Monte Carlo burnup simulations using the MCB5 code were performed to analyze the performance of the three conceptual ADS systems. Preliminary burnup analysis shows that all three conceptual ADS

  11. A UNIT, AN ASSEMBLY AND A METHOD FOR CONTROLLING IN A DYNAMIC EGOCENTRIC INTERACTIVE SPACE

    DEFF Research Database (Denmark)

    2007-01-01

    A portable unit for providing instructions for navigation in menus or controlling equipment, the unit having a user interface and a camera pointing in the general direction of the user. The unit tracking relative movements between the unit and the user and converting the relative movement into th...

  12. Design and control of three fingers motion for dexterous assembly of ...

    African Journals Online (AJOL)

    user

    hand (Salisbury et al, 1982), the Belgrade/USC hand (Bekey et al, 1999), the Utah/MIT Dexterous hand (Jacobsen, 2001) and the. LMS hand (Gazeau, 2001). However, significant efforts have still to be made to find designs simple enough to be easily built and controlled, in order to obtain practical systems (Bicchi, 2000).

  13. Design and control of three fingers motion for dexterous assembly of ...

    African Journals Online (AJOL)

    user

    fundamental type control scheme, such as independent grasping and manipulating motions or forces, has been clarified and is often employed by the robotics and automation researchers. Therefore, an extraordinary number of theoretical analyses of manipulators and robotic hands have been proposed, and their ...

  14. Controlling wetting and self-assembly dynamics by tailored hydrophobic and oleophobic surfaces.

    Science.gov (United States)

    Miele, Ermanno; Malerba, Mario; Dipalo, Michele; Rondanina, Eliana; Toma, Andrea; De Angelis, Francesco

    2014-06-25

    Tailored hydrophobic and oleophobic surfaces are exploited for controlling the wetting behaviour and evaporation process of solution dropped on them. This enables molecules and nano-objects that are dissolved in water or organic solvents to be delivered and arranged in a well-defined 2D layout. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ultra-Portable Smartphone Controlled Integrated Digital Microfluidic System in a 3D-Printed Modular Assembly

    Directory of Open Access Journals (Sweden)

    Mohamed Yafia

    2015-09-01

    Full Text Available Portable sensors and biomedical devices are influenced by the recent advances in microfluidics technologies, compact fabrication techniques, improved detection limits and enhanced analysis capabilities. This paper reports the development of an integrated ultraportable, low-cost, and modular digital microfluidic (DMF system and its successful integration with a smartphone used as a high-level controller and post processing station. Low power and cost effective electronic circuits are designed to generate the high voltages required for DMF operations in both open and closed configurations (from 100 to 800 V. The smartphone in turn commands a microcontroller that manipulate the voltage signals required for droplet actuation in the DMF chip and communicates wirelessly with the microcontroller via Bluetooth module. Moreover, the smartphone acts as a detection and image analysis station with an attached microscopic lens. The holder assembly is fabricated using three-dimensional (3D printing technology to facilitate rapid prototyping. The holder features a modular design that enables convenient attachment/detachment of a variety of DMF chips to/from an electrical busbar. The electrical circuits, controller and communication system are designed to minimize the power consumption in order to run the device on small lithium ion batteries. Successful controlled DMF operations and a basic colorimetric assay using the smartphone are demonstrated.

  16. 3D Orientational Control in Self-Assembled Thin Films with Sub-5 nm Features by Light.

    Science.gov (United States)

    Nickmans, Koen; Bögels, Gerardus M; Sánchez-Somolinos, Carlos; Murphy, Jeffrey N; Leclère, Philippe; Voets, Ilja K; Schenning, Albertus P H J

    2017-09-01

    While self-assembled molecular building blocks could lead to many next-generation functional organic nanomaterials, control over the thin-film morphologies to yield monolithic sub-5 nm patterns with 3D orientational control at macroscopic length scales remains a grand challenge. A series of photoresponsive hybrid oligo(dimethylsiloxane) liquid crystals that form periodic cylindrical nanostructures with periodicities between 3.8 and 5.1 nm is studied. The liquid crystals can be aligned in-plane by exposure to actinic linearly polarized light and out-of-plane by exposure to actinic unpolarized light. The photoalignment is most efficient when performed just under the clearing point of the liquid crystal, at which the cylindrical nanostructures are reoriented within minutes. These results allow the generation of highly ordered sub-5 nm patterns in thin films at macroscopic length scales, with control over the orientation in a noncontact fashion. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, R.E.

    1997-12-01

    Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments.

  18. Initial results on fault diagnosis of DSN antenna control assemblies using pattern recognition techniques

    Science.gov (United States)

    Smyth, P.; Mellstrom, J.

    1990-01-01

    Initial results obtained from an investigation using pattern recognition techniques for identifying fault modes in the Deep Space Network (DSN) 70 m antenna control loops are described. The overall background to the problem is described, the motivation and potential benefits of this approach are outlined. In particular, an experiment is described in which fault modes were introduced into a state-space simulation of the antenna control loops. By training a multilayer feed-forward neural network on the simulated sensor output, classification rates of over 95 percent were achieved with a false alarm rate of zero on unseen tests data. It concludes that although the neural classifier has certain practical limitations at present, it also has considerable potential for problems of this nature.

  19. Method of Optimizing the Construction of Machining, Assembly and Control Devices

    Science.gov (United States)

    Iordache, D. M.; Costea, A.; Niţu, E. L.; Rizea, A. D.; Babă, A.

    2017-10-01

    Industry dynamics, driven by economic and social requirements, must generate more interest in technological optimization, capable of ensuring a steady development of advanced technical means to equip machining processes. For these reasons, the development of tools, devices, work equipment and control, as well as the modernization of machine tools, is the certain solution to modernize production systems that require considerable time and effort. This type of approach is also related to our theoretical, experimental and industrial applications of recent years, presented in this paper, which have as main objectives the elaboration and use of mathematical models, new calculation methods, optimization algorithms, new processing and control methods, as well as some structures for the construction and configuration of technological equipment with a high level of performance and substantially reduced costs..

  20. Controlled assembly of artificial protein-protein complexes via DNA duplex formation.

    Science.gov (United States)

    Płoskoń, Eliza; Wagner, Sara C; Ellington, Andrew D; Jewett, Michael C; O'Reilly, Rachel; Booth, Paula J

    2015-03-18

    DNA-protein conjugates have found a wide range of applications. This study demonstrates the formation of defined, non-native protein-protein complexes via the site specific labeling of two proteins of interest with complementary strands of single-stranded DNA in vitro. This study demonstrates that the affinity of two DNA-protein conjugates for one another may be tuned by the use of variable lengths of DNA allowing reversible control of complex formation.

  1. Roughness-controlled self-assembly of mannitol/LB agar microparticles by polymorphic transformation for pulmonary drug delivery.

    Science.gov (United States)

    Zhang, Fengying; Ngoc, Nguyen Thi Quynh; Tay, Bao Hui; Mendyk, Aleksander; Shao, Yu-Hsuan; Lau, Raymond

    2015-01-05

    Novel roughness-controlled mannitol/LB Agar microparticles were synthesized by polymorphic transformation and self-assembly method using hexane as the polymorphic transformation reagent and spray-dried mannitol/LB Agar microparticles as the starting material. As-prepared microparticles were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction spectra (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Andersen Cascade Impactor (ACI). The XRD and DSC results indicate that after immersing spray-dried mannitol/LB Agar microparticles in hexane, β-mannitol was completely transformed to α-mannitol in 1 h, and all the δ-mannitol was transformed to α form after 14 days. SEM shows that during the transformation the nanobelts on the spray-dried mannitol/LB Agar microparticles become more dispersed and the contour of the individual nanobelts becomes more noticeable. Afterward, the nanobelts self-assemble to nanorods and result in rod-covered mannitol/LB Agar microparticles. FTIR indicates new hydrogen bonds were formed among mannitol, LB Agar, and hexane. SEM images coupled with image analysis software reveal that different surface morphology of the microparticles have different drug adhesion mechanisms. Comparison of ACI results and image analysis of SEM images shows that an increase in the particle surface roughness can increase the fine particle fractions (FPFs) using the rod-covered mannitol microparticles as drug carriers. Transformed microparticles show higher FPFs than commercially available lactose carriers. An FPF of 28.6 ± 2.4% was achieved by microparticles transformed from spray-dried microparticles using 2% mannitol(w/v)/LB Agar as feed solution. It is comparable to the highest FPF reported in the literature using lactose and spray-dried mannitol as carriers.

  2. Self-assembly and gelation of poly(aryl ether) dendrons containing hydrazide units: factors controlling the formation of helical structures.

    Science.gov (United States)

    Malakar, Partha; Prasad, Edamana

    2015-03-23

    Self-assembly of AB2 and AB3 type low molecular weight poly(aryl ether) dendrons that contain hydrazide units were used to investigate mechanistic aspects of helical structure formation during self-assembly. The results suggest that there are three important aspects that control helical structure formation in such systems with acyl hydrazide/hydrazone linkage: i) J-type aggregation, ii) the hydrogen-bond donor/acceptor ability of the solvent, and iii) the dielectric constant of the solvent. The monomer units self-assemble to form dimer structures through hydrogen-bonding and further assembly of the hydrogen-bonded dimers leads to macroscopic chirality in the present case. Dimer formation was confirmed by NMR spectroscopy and by mass spectrometry. The self-assembly in the system was driven by hydrogen-bonding and π-π stacking interactions. The morphology of the aggregates formed was examined by scanning electron microscopy, and the analysis suggests that aprotic solvent systems facilitate helical fibre formation, whereas introduction of protic solvents results in the formation of flat ribbons. This detailed mechanistic study suggests that the self-assembly follows a nucleation-elongation model to form helical structures, rather than the isodesmic model. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Controlled assembly of organic whispering-gallery-mode microlasers as highly sensitive chemical vapor sensors.

    Science.gov (United States)

    Gao, Miaomiao; Wei, Cong; Lin, Xianqing; Liu, Yuan; Hu, Fengqin; Zhao, Yong Sheng

    2017-03-09

    We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.

  4. Software protocol design: Communication and control in a multi-task robot machine for ITER vacuum vessel assembly and maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming, E-mail: ming.li@lut.fi [Laboratory of Intelligent Machines, Lappeenranta University of Technology (Finland); Wu, Huapeng; Handroos, Heikki [Laboratory of Intelligent Machines, Lappeenranta University of Technology (Finland); Yang, Guangyou [School of Mechanical Engineering, Hubei University of Technology, Wuhan (China); Wang, Yongbo [Laboratory of Intelligent Machines, Lappeenranta University of Technology (Finland)

    2015-10-15

    Highlights: • A high-level protocol is proposed for the data inter-transmission. • The protocol design is task-oriented for the robot control in the software system. • The protocol functions as a role of middleware in the software. • The protocol running stand-alone as an independent process in the software provides greater security. • Providing a reference design protocol for the multi-task robot machine in the industry. - Abstract: A specific communication and control protocol for software design of a multi-task robot machine is proposed. In order to fulfill the requirements on the complicated multi machining functions and the high performance motion control, the software design of robot is divided into two main parts accordingly, which consists of the user-oriented HMI part and robot control-oriented real-time control system. The two parts of software are deployed in the different hardware for the consideration of run-time performance, which forms a client–server-control architecture. Therefore a high-level task-oriented protocol is designed for the data inter-communication between the HMI part and the control system part, in which all the transmitting data related to a machining task is divided into three categories: trajectory-oriented data, task control-oriented data and status monitoring-oriented data. The protocol consists of three sub-protocols accordingly – a trajectory protocol, task control protocol and status protocol – which are deployed over the Ethernet and run as independent processes in both the client and server computers. The protocols are able to manage the vast amounts of data streaming due to the multi machining functions in a more efficient way. Since the protocol is functioning in the software as a role of middleware, and providing the data interface standards for the developing groups of two parts of software, it also permits greater focus of both software parts developers on their own requirements-oriented design. By

  5. A vibrating membrane bioreactor operated at supra- and sub-critical flux: Influence of extracellular polymeric substances from yeast cells

    DEFF Research Database (Denmark)

    Beier, Søren Prip; Jonsson, Gunnar Eigil

    2007-01-01

    A vibrating membrane bioreactor, in which the fouling problems are reduced by vibrating a hollow fiber membrane module, has been tested in constant flux microfiltration above (supra-critical) and below (sub-critical) an experimentally determined critical flux. Suspensions of bakers yeast cells were....... Filtration just below the critical flux (sub-critical) seems to be a good compromise between acceptable flux level and acceptable increase of fouling resistance and trans-membrane pressure (TMP) in a given time period. EPS from the yeast cells causes the membrane module to foul and part of the fouling...... is continually washed out during supra-critical flux operation whereas the washing out at sub-critical flux operation is not observed. This might be due to locally different hydrodynamic conditions at the membrane surface and pore entrances at supra- and sub-critical flux respectively....

  6. Subcritical tests - nuclear weapon testing under the Comprehensive Test Ban Treaty; Subkritiske tester - kjernevaapentesting under avtalen om fullstendig proevestans

    Energy Technology Data Exchange (ETDEWEB)

    Hoeibraaten, S

    1998-10-01

    The report discusses possible nuclear weapons related experiments and whether these are permitted under the 1996 Comprehensive Test Ban Treaty (CTBT). The term ''subcritical experiments'' as used in the United States includes experiments in which one studies fissile materials (so far only plutonium) under extreme conditions generated by conventional high explosives, and in which a self-sustained chain reaction never develops in the fissile material. The known facts about the American subcritical experiments are presented. There is very little reason to doubt that these experiments were indeed subcritical and therefore permitted under the CTBT. Little is known about the Russian efforts that are being made on subcritical experiments.

  7. PILOT-SCALE SUBCRITICAL WATER REMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON- AND PESTICIDE-CONTAMINATED SOIL. (R825394)

    Science.gov (United States)

    Subcritical water (hot water under enough pressure to maintain the liquid state) was used to remove polycyclic aromatic hydrocarbons (PAHs) and pesticides from highly contaminated soils. Laboratory-scale (8 g of soil) experiments were used to determine conditions f...

  8. Light-controlled drug releasing polymer films combining LbL self-assembly and host-guest interactions

    Directory of Open Access Journals (Sweden)

    J. Li

    2014-03-01

    Full Text Available By combining LbL (layer-by-layer self-assembly approach and host-guest interactions, a unique multilayer film was constructed and employed for a light-controlled drug release system. The drug molecules can be loaded and released into the resulting polyelectrolyte multilayers containing azobenzene (Azo function groups by using the irradiation of visible light and UV light alternately. The photo-sensitivity of the multilayer films was studied through UV-vis spectrum, fluorescence spectrum and confocal microscopy. The target molecules could be rapidly released from the multilayers after 300 W UV light irradiation for 20 minutes. Moreover, they could be readsorbed into the multilayers uniformly when illuminated under the 300 W visible light for 10 minutes confirmed by the observation of confocal microscopy, and the readsorption ratio exceeds 100% evidenced from UV–vis spectroscopy. After several cycles of the above-mentioned process, the multilayer films show good fatigue resistance. All these results indicate the photo-sensitivity and high-efficiency of the multilayer films, which have great potential in controlled drug delivery platform and biomedical applications.

  9. Changing Mad2 levels affects chromosome segregation and spindle assembly checkpoint control in female mouse meiosis I.

    Directory of Open Access Journals (Sweden)

    Théodora Niault

    Full Text Available The spindle assembly checkpoint (SAC ensures correct separation of sister chromatids in somatic cells and provokes a cell cycle arrest in metaphase if one chromatid is not correctly attached to the bipolar spindle. Prolonged metaphase arrest due to overexpression of Mad2 has been shown to be deleterious to the ensuing anaphase, leading to the generation of aneuploidies and tumorigenesis. Additionally, some SAC components are essential for correct timing of prometaphase. In meiosis, we and others have shown previously that the Mad2-dependent SAC is functional during the first meiotic division in mouse oocytes. Expression of a dominant-negative form of Mad2 interferes with the SAC in metaphase I, and a knock-down approach using RNA interference accelerates anaphase onset in meiosis I. To prove unambigiously the importance of SAC control for mammalian female meiosis I we analyzed oocyte maturation in Mad2 heterozygote mice, and in oocytes overexpressing a GFP-tagged version of Mad2. In this study we show for the first time that loss of one Mad2 allele, as well as overexpression of Mad2 lead to chromosome missegregation events in meiosis I, and therefore the generation of aneuploid metaphase II oocytes. Furthermore, SAC control is impaired in mad2+/- oocytes, also leading to the generation of aneuploidies in meiosis I.

  10. Topology and Shape Control for Assemblies of Block Copolymer Blends in Solution

    KAUST Repository

    Moreno Chaparro, Nicolas

    2015-10-27

    We study binary blends of asymmetric diblock copolymers (AB/AC) in selective solvents with a mesoscale model. We investigate the morphological transitions induced by the concentration of the AC block copolymer and the difference in molecular weight between the AB and AC copolymers, when segments B and C exhibit hydrogen-bonding interactions. To the best of our knowledge, this is the first work modeling mixtures of block copolymers with large differences in molecular weight. The coassembly mechanism localizes the AC molecules at the interface of A and B domains and induces the swelling of the B-rich domains. The coil size of the large molecular weight block copolymer depends only on the concentration of the short block copolymer (AC or AB), regardless of the B–C interactions. However, the B–C interactions control the morphological transitions that occur in these blends.

  11. Enzyme-Controlled Intracellular Self-Assembly of (18)F Nanoparticles for Enhanced MicroPET Imaging of Tumor.

    Science.gov (United States)

    Liu, Yaling; Miao, Qingqing; Zou, Pei; Liu, Longfei; Wang, Xiaojing; An, Linna; Zhang, Xiaoliu; Qian, Xiangping; Luo, Shineng; Liang, Gaolin

    2015-01-01

    Herein, we report the development of a new "smart" radioactive probe (i.e., 1) which can undergo furin-controlled condensation and self-assembly of radioactive nanoparticles (i.e., 1-NPs) in tumor cells and its application for enhanced microPET imaging of tumors in nude mice co-injected with its cold analog (i.e., 1-Cold). Furin-controlled condensation of 1-Cold and self-assembly of its nanoparticles (i.e., 1-Cold-NPs) in vitro were validated and characterized with HPLC, mass spectra, SEM, and TEM analyses. Cell uptake studies showed that both 1 and 1-Cold have good cell permeability. TEM images of 1-Cold-treated MDA-MB-468 cells directly uncovered that the intracellular 1-Cold-NPs were at/near the location of furin (i.e., Golgi bodies). MTT results indicated that 50 µM 1-Cold did not impose cytotoxicity to MDA-MB-468 cells up to 12 hours. MicroPET imaging of MDA-MB-468 tumor-bearing mice indicated that mice co-injected with 1 and 1-Cold showed higher uptake and longer attenuation of the radioactivity in tumors than those mice only injected with same dosage of 1. Tumor uptake ratios of 1 between these two groups of mice reached the maximum of 8.2 folds at 240 min post injection. Biodistribution study indicated that the uptake ratios of 1 in kidneys between these two groups continuously increased and reached 81.9 folds at 240 min post injection, suggesting the formation of radioactive NPs (i.e., 1-NPs) in MDA-MB-468 tumors of mice co-injected with 1 and 1-Cold. And the nanoparticles were slowly digested and secreted from the tumors, accumulating in the kidneys. Our ''smart'' probe (i.e., 1), together with the strategy of co-injection, might help researchers trace the biomarkers of interest within a longer time window.

  12. Sequence assembly

    DEFF Research Database (Denmark)

    Scheibye-Alsing, Karsten; Hoffmann, S.; Frankel, Annett Maria

    2009-01-01

    Despite the rapidly increasing number of sequenced and re-sequenced genomes, many issues regarding the computational assembly of large-scale sequencing data have remain unresolved. Computational assembly is crucial in large genome projects as well for the evolving high-throughput technologies...... and plays an important role in processing the information generated by these methods. Here, we provide a comprehensive overview of the current publicly available sequence assembly programs. We describe the basic principles of computational assembly along with the main concerns, such as repetitive sequences...... in genomic DNA, highly expressed genes and alternative transcripts in EST sequences. We summarize existing comparisons of different assemblers and provide a detailed descriptions and directions for download of assembly programs at: http://genome.ku.dk/resources/assembly/methods.html....

  13. Metal ion controlled self-assembly of a chemically reengineered protein drug studied by small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Jesper, Nygaard; Munch, Henrik K.; Thulstrup, Peter W.

    2012-01-01

    Precise control of the oligomeric state of proteins is of central importance for biological function and for the properties of biopharmaceutical drugs. Here, the self-assembly of 2,2′-bipyridine conjugated monomeric insulin analogues, induced through coordination to divalent metal ions, was studi...

  14. Controllable assembly of well-defined monodisperse Au nanoparticles on hierarchical ZnO microspheres for enhanced visible-light-driven photocatalytic and antibacterial activity.

    Science.gov (United States)

    Wang, Yuan; Fang, Hua-Bin; Zheng, Yan-Zhen; Ye, Rongqin; Tao, Xia; Chen, Jian-Feng

    2015-12-07

    A high-efficiency visible-light-driven photocatalyst composed of homogeneously distributed Au nanoparticles (AuNPs) well-defined on hierarchical ZnO microspheres (ZMS) via a controllable layer-by-layer self-assembly technique is demonstrated. The gradual growth of the characteristic absorption bands of Au loaded on ZnO in the visible light region with an increasing number of assemblies indicates the enhancement of the light harvesting ability of the ZMS/Au composites as well as the reproducibility and controllability of the entire assembly process. Results on the photoelectrochemical performance characterized by EIS and transient photocurrent response spectra indicate that the ZMS/Au composites possess increased photoinduced charge separation and transfer efficiency compared to the pure ZMS film. As a result, the hybrid composites exhibited enhanced decomposition activity for methylene blue and salicylic acid as well as antibacterial activity in killing S. aureus and E. coli under visible light irradiation. It can be noted that well-distributed Au components even at a rather low Au/ZnO weight ratio of ∼1.2% also exhibited extraordinary photocatalysis. Such a facile and controllable self-assembly approach may be viable for preparing high-performance visible-light-driven ZMS/Au photocatalysts in a simple and controllable way, and consequently, the technology may extend to other plasmon-enhanced heterostructures made of nanostructured semiconductors and noble metals for great potential application in environmental protection.

  15. In vitro collagen fibril assembly: thermodynamic studies.

    Science.gov (United States)

    Na, G C; Phillips, L J; Freire, E I

    1989-09-05

    The in vitro fibril assembly of calf skin collagen was examined as a function of ionic strength and temperature. In a 0.03 M NaPi, pH 7.0, buffer, fibril assembly required a minimum critical concentration of collagen. At nearly physiological ionic strengths and temperatures, the critical concentration was less than 1 microgram/mL and required a very sensitive method for measurement. Raising the ionic strength of the buffer resulted first in higher and then lower critical concentrations. Raising the temperature led to lower critical concentrations. A van't Hoff plot of the fibril growth constant calculated from the critical concentration gave positive enthalpy changes and positive heat capacity changes which indicate that the fibril growth is driven by both hydrophobic and ionic inter-collagen interactions. Sedimentation equilibrium studies showed the collagen to be monomeric at subcritical concentrations. Differential scanning microcalorimetric studies showed only one very sharp heat absorption peak for the fibril assembly which coincided with the appearance of solution turbidity. Within experimental error, the enthalpy changes of the fibril assembly measured with the microcalorimeter were of the same magnitude as the van't Hoff enthalpy changes. These results are discussed in light of a cooperative nucleation-growth mechanism of collagen fibril assembly proposed earlier.

  16. A fusion-driven subcritical system concept based on viable technologies

    Science.gov (United States)

    Wu, Y.; Jiang, J.; Wang, M.; Jin, M.; FDS Team

    2011-10-01

    A fusion-driven hybrid subcritical system (FDS) concept has been designed and proposed as spent fuel burner based on viable technologies. The plasma fusion driver can be designed based on relatively easily achieved plasma parameters extrapolated from the successful operation of existing fusion experimental devices such as the EAST tokamak in China and other tokamaks in the world, and the subcritical fission blanket can be designed based on the well-developed technologies of fission power plants. The simulation calculations and performance analyses of plasma physics, neutronics, thermal-hydraulics, thermomechanics and safety have shown that the proposed concept can meet the requirements of tritium self-sufficiency and sufficient energy gain as well as effective burning of nuclear waste from fission power plants and efficient breeding of nuclear fuel to feed fission power plants.

  17. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2017-02-01

    Full Text Available Electrothermal energy storage (ETES provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analysis results show that the extremum principle of entransy dissipation is an effective criterion for the optimization, and the optimum heat transfer for different cases with the same mass flux or pressure has been discussed. The optimum heat transfer can be achieved by adjusting the mass flux and pressure of the working fluid. It also reveals that with the increase of mass flux, there is a minimum exergy in the range under consideration, and the exergy decreases with the increase of the pressure.

  18. Determination of subcriticality and effective source strength by source drop and jerk experiments

    Energy Technology Data Exchange (ETDEWEB)

    Taninaka, Hiroshi [Interdisciplinary Graduate School of Science and Technology, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan); Hashimoto, Kengo [Atomic Energy Research Institute, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2008-07-01

    This paper presents applicability of least squares inverse kinetics method (LSIKM) to source drop and source jerk experiments. The LSIKM can estimate both reactivity and source strength by applying least square approximation to a correlation between time-sequence count data and inverse kinetics analysis data. The experiments were performed in the UTR-KINKI reactor to demonstrate the applicability of the LSIKM. To source jerk data, for comparison, conventional integral method is also applied. In the subcriticality and source strength obtained by the LSIKM, spatial dependence is slightly observed. However, the integral method leads to significant spatial dependence. The sub-criticalities inferred from source drop data are consistent with the results from source jerk data. (authors)

  19. Subcritical ethanol extraction of flavonoids from Moringa oleifera leaf and evaluation of antioxidant activity.

    Science.gov (United States)

    Wang, Yongqiang; Gao, Yujie; Ding, Hui; Liu, Shejiang; Han, Xu; Gui, Jianzhou; Liu, Dan

    2017-03-01

    A large-scale process to extract flavonoids from Moringa oleifera leaf by subcritical ethanol was developed and HPLC-MS analysis was conducted to qualitatively identify the compounds in the extracts. To optimize the effects of process parameters on the yield of flavonoids, a Box-Behnken design combined with response surface methodology was conducted in the present work. The results indicated that the highest extraction yield of flavonoids by subcritical ethanol extraction could reach 2.60% using 70% ethanol at 126.6°C for 2.05h extraction. Under the optimized conditions, flavonoids yield was substantially improved by 26.7% compared with the traditional ethanol reflux method while the extraction time was only 2h, and obvious energy saving was observed. FRAP and DPPH assays showed that the extracts had strong antioxidant and free radical scavenging activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Coupling of subcritical methanol with acidic ionic liquids for the acidity reduction of naphthenic acids

    Directory of Open Access Journals (Sweden)

    Zafar Faisal

    2017-09-01

    Full Text Available The presence of naphthenic acids (NAs in crude oil is the major cause of corrosion in the refineries and its processing equipment. The goal of this study is to reduce the total acid number (TAN of NAs by treating them with subcritical methanol in the presence of acidic ionic liquid (AIL catalysts. Experiments were carried out in an autoclave batch reactor and the effect of different reaction parameters was investigated. It was observed that TAN reduction was positively dependent on the temperature and concentration of the AIL whereas excess of methanol has a negative effect. Approximately 90% TAN reduction was achieved under the optimized reaction conditions using [BMIM]HSO4 as catalyst. It was also perceived from the experimental results that the AILs with longer alkyl chain exhibited higher catalytic activity. The activity and stability of AIL showed that they can be promising catalyst to esterify NAs under subcritical methanol.

  1. Enhanced enzymatic cellulose hydrolysis by subcritical carbon dioxide pretreatment of sugarcane bagasse.

    Science.gov (United States)

    Zhang, Hongdan; Wu, Shubin

    2014-04-01

    Most biomass pretreatment processes for sugar production are run at low-solid concentration (carbon dioxide (CO2) could provide a more sustainable pretreatment medium while using relative high-solid contents (15 wt.%). The effects of subcritical CO2 pretreatment of sugarcane bagasse to the solid and glucan recoveries at different pretreatment conditions were investigated. Subsequently, enzymatic hydrolysis at different hydrolysis time was applied to obtain maximal glucose yield, which can be used for ethanol fermentation. The maximum glucose yield in enzyme hydrolyzate reached 38.5 g based on 100g raw material after 72 h of enzymatic hydrolysis, representing 93.0% glucose in sugarcane bagasse. The enhanced digestibilities of subcritical CO2 pretreated sugarcane bagasse were due to the removal of hemicellulose, which were confirmed by XRD, FTIR, SEM, and TGA analyses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Equilibria of ternary system acetic acid-water-CO2 under subcritical conditions

    DEFF Research Database (Denmark)

    Gutierrez, Jose M. Jimenez; Mussatto, Solange I.; Tsou, Joana

    in a very wide range of applications. However, those conditions, especially the levels of high pressure required at larger scale, involve certain equipment limitations. An alternative to overcome those restrictions is to use subcritical carbon dioxide. In order to understand the different systems......) of the ternary system HAc—H2O—CO2 at different subcritical conditions. A proposed computer model could be validated with experimental data, leading to a certain degree of adjustment due to specific factors, such as the binary interaction parameter kij, used in the model based on the Peng-Robinson EoS coupled...... it will be returned to the atmosphere (as part of the carbon cycle), CO2 is an inexpensive and clean source with numerous industrial applications in diverse fields: from chemical processes to biotechnological purposes [1]. Many of these studies have been focused on supercritical CO2, due to its broad potential uses...

  3. Sub-Critical Closed String Field Theory in D Less Than 26

    OpenAIRE

    Kaku, Michio

    1993-01-01

    We construct the second quantized action for sub-critical closed string field theory with zero cosmological constant in dimensions $ 2 \\leq D < 26$, generalizing the non-polynomial closed string field theory action proposed by the author and the Kyoto and MIT groups for $D = 26$. The proof of gauge invariance is considerably complicated by the presence of the Liouville field $\\phi$ and the non-polynomial nature of the action. However, we explicitly show that the polyhedral vertex functions ob...

  4. Sensitivity Analysis of Core Neutronic Parameters in Electron Accelerator-driven Subcritical Advanced Liquid Metal Reactor

    OpenAIRE

    Ebrahimkhani, Marziye; Hassanzadeh, Mostafa; Feghhi, Sayed Amier Hossian; Masti, Darush

    2016-01-01

    Calculation of the core neutronic parameters is one of the key components in all nuclear reactors. In this research, the energy spectrum and spatial distribution of the neutron flux in a uranium target have been calculated. In addition, sensitivity of the core neutronic parameters in accelerator-driven subcritical advanced liquid metal reactors, such as electron beam energy (Ee) and source multiplication coefficient (ks), has been investigated. A Monte Carlo code (MCNPX_2.6) has been used to ...

  5. Subcritical mineralization of sodium salt of dodecyl benzene sulfonate using sonication-wet oxidation (SONIWO) technique.

    Science.gov (United States)

    Dhale, A D; Mahajani, V V

    2001-06-01

    Subcritical mineralization of sodium salt of dodecyl benzene sulfonate via hybrid process-sonication followed by wet oxidation (SONIWO) has been investigated. Sonication of the compound enhanced the rates and % COD reduction during wet oxidation. In this process, homogenous CuSO4 catalyst was found to be effective. In wet oxidation studies, phenol, hydroquinone, maleic acid, oxalic acid, propionic acid, and acetic acid were identified as intermediates. The global rate equations for wet oxidation in terms of COD reduction were developed.

  6. Morphology control of polymer: Fullerene solar cells by nanoparticle self-assembly

    Science.gov (United States)

    Zhang, Wenluan

    During the past two decades, research in the field of polymer based solar cells has attracted great effort due to their simple processing, mechanical flexibility and potential low cost. A standard polymer solar cell is based on the concept of a bulk-heterojunction composed of a conducting polymer as the electron donor and a fullerene derivative as the electron acceptor. Since the exciton lifetime is limited, this places extra emphasis on control of the morphology to obtain improved device performance. In this thesis, detailed characterization and novel morphological design of polymer solar cells was studied, in addition, preliminary efforts to transfer laboratory scale methods to industrialized device fabrication was made. Magnetic contrast neutron reflectivity was used to study the vertical concentration distribution of fullerene nanoparticles within poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b]thiophene (pBTTT) thin film. Due to the wide space between the side chains of polymer, these fullerene nanoparticles intercalate between them creating a stable co-crystal structure. Therefore, a high volume fraction of fullerene was needed to obtain optimal device performance as phase separated conductive pathways are required and resulted in a homogeneous fullerene concentration profile through the film. Small angle neutron scattering was used to find there is amorphous fullerene even at lower concentration since it was previously believed that all fullerene formed a co-crystal. These fullerene molecules evolve into approximately 15 nm sized agglomerates at higher concentrations to improve electron transport. Unfortunately, thermal annealing gives these agglomerates mobility to form micrometer sized crystals and reduce the device performance. In standard poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCMBM) solar cells, a higher concentration of PCBM at the cathode interface is desired due to the band alignment structure. This was

  7. Observation of subcritical geodesic acoustic mode excitation in the large helical device

    Science.gov (United States)

    Ido, T.; Itoh, K.; Lesur, M.; Osakabe, M.; Shimizu, A.; Ogawa, K.; Nishiura, M.; Yamada, I.; Yasuhara, R.; Kosuga, Y.; Sasaki, M.; Ida, K.; Inagaki, S.; Itoh, S.-I.; the LHD Experiment Group

    2017-07-01

    The abrupt and strong excitation of the geodesic acoustic mode (GAM) has been found in the large helical device (LHD), when the frequency of a chirping energetic particle-driven GAM (EGAM) approaches twice that of the GAM frequency. The temporal evolution of the phase relation between the abrupt GAM and the chirping EGAM is common in all events. The result indicates a coupling between the GAM and the EGAM. In addition, the nonlinear evolution of the growth rate of the GAM is observed, and there is a threshold in the amplitude of the GAM for the appearance of nonlinear behavior. A threshold in the amplitude of the EGAM for the abrupt excitation of the GAM is also observed. According to one theory (Lesur et al 2016 Phys. Rev. Lett. 116 015003, Itoh et al 2016 Plasma Phys. Rep. 42 418) the observed abrupt phenomenon can be interpreted as the excitation of the subcritical instability of the GAM. The excitation of a subcritical instability requires a trigger and a seed with sufficient amplitude. The observed threshold in the amplitude of the GAM seems to correspond with the threshold in the seed, and the threshold in the amplitude of the EGAM seems to correspond with the threshold in the magnitude of the trigger. Thus, the observed threshold supports the interpretation that the abrupt phenomenon is the excitation of a subcritical instability of the GAM.

  8. Efficient decomposition of perchlorate to chloride ions in subcritical water by use of steel slag.

    Science.gov (United States)

    Hori, Hisao; Kamijo, Ayae; Inoue, Miki; Chino, Asako; Wu, Qian; Kannan, Kurunthachalam

    2016-08-03

    Decomposition of perchlorate (ClO4(-)) in subcritical water in the presence of steel slag, a by-product of the steel industry, was investigated. Reactivity of ClO4(-) was low in pure subcritical water state up to 300 °C, whereas adding steel slag efficiently accelerated the decomposition of ClO4(-) to Cl(-), with no leaching of heavy metals such as chromium and other environmentally undesirable elements (boron and fluorine). When the reaction was performed in subcritical water at a relatively low temperature (250 °C) for 6 h, virtually all ClO4(-) ions were removed from the reaction solution. The concentration of Cl(-) after the reaction was well accounted for by the sum of the amount of Cl(-) ascribed to the decomposition of ClO4(-) and the amount of Cl(-) leached from the slag. This method was successfully applied to decompose ClO4(-) in water samples collected from a man-made reflection pond following a fireworks display, even though these samples contained much higher concentrations of Cl(-) and SO4(2-) than ClO4(-).

  9. Size- and shape-controlled synthesis of hexagonal bipyramidal crystals and hollow self-assembled Al-MOF spheres

    KAUST Repository

    Sarawade, Pradip

    2013-11-25

    We report an efficient protocol for the synthesis of monodisperse crystals of an aluminum (Al)-based metal organic framework (MOF) while obtaining excellent control over the size and shape solely by tuning of the reaction parameters without the use of a template or structure-directing agent. The size of the hexagonal crystals of the Al-MOF can be selectively varied from 100 nm to 2000 nm by simply changing the reaction time and temperature via its nucleation-growth mechanism. We also report a self-assembly phenomenon, observed for the first time in case of Al-MOF, whereby hollow spheres of Al-MOF were formed by the spontaneous organization of triangular sheet building blocks. These MOFs showed broad hysteresis loops during the CO2 capture, indicating that the adsorbed CO2 is not immediately desorbed upon decreasing the external pressure and is instead confined within the framework, which allows for the capture and subsequent selective trapping of CO2 from gaseous mixtures. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fuel cell integral bundle assembly including ceramic open end seal and vertical and horizontal thermal expansion control

    Science.gov (United States)

    Zafred, Paolo R [Murrysville, PA; Gillett, James E [Greensburg, PA

    2012-04-24

    A plurality of integral bundle assemblies contain a top portion with an inlet fuel plenum and a bottom portion containing a base support, the base supports a dense, ceramic air exhaust manifold having four supporting legs, the manifold is below and connects to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the open end of the fuel cells rest upon and within a separate combination ceramic seal and bundle support contained in a ceramic support casting, where at least one flexible cushion ceramic band seal located between the recuperator and fuel cells protects and controls horizontal thermal expansion, and where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all of the weight of the generator.

  11. Constructing of DNA vectors with controlled nanosize and single dispersion by block copolymer coating gold nanoparticles as template assembly

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junbo, E-mail: Lijunbo@haust.edu.cn [Henan University of Science and Technology, School of Chemical Engineering and Pharmaceutics (China); Wu, Wenlan [Henan University of Science and Technology, School of Medicine (China); Gao, Jiayu; Liang, Ju; Zhou, Huiyun; Liang, Lijuan [Henan University of Science and Technology, School of Chemical Engineering and Pharmaceutics (China)

    2017-03-15

    Synthesized vectors with nanoscale size and stable colloid dispersion are highly desirable for improving gene delivery efficiency. Here, a core-shell template particle was constructed with polyethylene glycol-b-poly1-(3-aminopropyl)-3-(2-methacryloyloxy propylimidazolium bromine) (PEG-b-PAMPImB) coating gold nanoparticles (PEG-b-PAMPImB-@-Au NPs) for loading DNA and delivering in vitro. Data from transmission electron microscopy (TEM) and dynamic light scattering (DLS) suggest that these nanoplexes, by forming an electrostatic complex with DNA at the inner PAMPImB shell, offer steric protection for the outer PEG corona leading to single dispersion and small size. Notably, higher colloid stability and lower cytotoxicity were achieved with these nanoplexes when compared with PAMPImB monolayer-coated gold nanoparticles (Au NPs). Confocal laser scanning microscopy and intracellular trafficking TEM further indicate that the nanoplexes can translocate across the cell membrane and partly enter the nucleus for high efficient expression. Thus, template assembly represents a promising approach to control the size and colloid stability of gene vectors and ensure safety and efficiency of DNA delivery.

  12. Constructing of DNA vectors with controlled nanosize and single dispersion by block copolymer coating gold nanoparticles as template assembly

    Science.gov (United States)

    Li, Junbo; Wu, Wenlan; Gao, Jiayu; Liang, Ju; Zhou, Huiyun; Liang, Lijuan

    2017-03-01

    Synthesized vectors with nanoscale size and stable colloid dispersion are highly desirable for improving gene delivery efficiency. Here, a core-shell template particle was constructed with polyethylene glycol- b-poly1-(3-aminopropyl)-3-(2-methacryloyloxy propylimidazolium bromine) (PEG- b-PAMPImB) coating gold nanoparticles (PEG- b-PAMPImB-@-Au NPs) for loading DNA and delivering in vitro. Data from transmission electron microscopy (TEM) and dynamic light scattering (DLS) suggest that these nanoplexes, by forming an electrostatic complex with DNA at the inner PAMPImB shell, offer steric protection for the outer PEG corona leading to single dispersion and small size. Notably, higher colloid stability and lower cytotoxicity were achieved with these nanoplexes when compared with PAMPImB monolayer-coated gold nanoparticles (Au NPs). Confocal laser scanning microscopy and intracellular trafficking TEM further indicate that the nanoplexes can translocate across the cell membrane and partly enter the nucleus for high efficient expression. Thus, template assembly represents a promising approach to control the size and colloid stability of gene vectors and ensure safety and efficiency of DNA delivery.

  13. Controlled assembly of high-order nanoarray metal structures on bulk copper surface by femtosecond laser pulses

    Science.gov (United States)

    Qin, Wanwan; Yang, Jianjun

    2017-07-01

    We report a new one-step maskless method to fabricate high-order nanoarray metal structures comprising periodic grooves and particle chains on a single-crystal Cu surface using femtosecond laser pulses at the central wavelength of 400 nm. Remarkably, when a circularly polarized infrared femtosecond laser pulse (spectrally centered at 800 nm) pre-irradiates the sample surface, the geometric dimensions of the composite structure can be well controlled. With increasing the energy fluence of the infrared laser pulse, both the groove width and particle diameter are observed to reduce, while the measured spacing-to-diameter ratio of the nanoparticles tends to present an increasing tendency. A physical scenario is proposed to elucidate the underlying mechanisms: as the infrared femtosecond laser pulse pre-irradiates the target, the copper surface is triggered to display anomalous transient physical properties, on which the subsequently incident Gaussian blue laser pulse is spatially modulated into fringe-like energy depositions via the excitation of ultrafast surface plasmon. During the following relaxation processes, the periodically heated thin-layer regions can be transferred into the metastable liquid rivulets and then they break up into nanodroplet arrays owing to the modified Rayleigh-like instability. This investigation indicates a simple integrated approach for active designing and large-scale assembly of complexed functional nanostructures on bulk materials.

  14. "Bis-Click" Ligation of DNA: Template-Controlled Assembly, Circularisation and Functionalisation with Bifunctional and Trifunctional Azides.

    Science.gov (United States)

    Yang, Haozhe; Seela, Frank

    2017-03-08

    Ligation and circularisation of oligonucleotides containing terminal triple bonds was performed with bifunctional or trifunctional azides. Both reactions are high yielding. Template-assisted bis-click ligation of two individual non-complementary oligonucleotide strands was accomplished to yield heterodimers exclusively. In this context, the template fulfils two functions: it accelerates the ligation reaction and controls product assembly (heterodimer vs. homodimer formation). Intermolecular bis-click circularisation of one oligonucleotide strand took place without template assistance. For construction of oligonucleotides with terminal triple bonds in the nucleobase side chain, 7- or 5-functionalised 7-deaza-dA and dU residues were used. These oligonucleotides are directly accessible by solid-phase synthesis. When trifunctional azides were employed instead of bifunctional linkers, functionalisation of the remaining azido group was performed with small molecules such as 1-ethynyl pyrene, biotin propargyl amide or with ethynylated oligonucleotides. By this means, branched DNA was constructed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Aromatic Cross-Strand Ladders Control the Structure and Stability of [beta]-Rich Peptide Self-Assembly Mimics

    Energy Technology Data Exchange (ETDEWEB)

    Biancalana, Matthew; Makabe, Koki; Koide, Akiko; Koide, Shohei (UC)

    2009-09-02

    Though {beta}-rich self-assemblies comprise a major structural class of polypeptides, a detailed understanding of the determinants of their structure and stability is lacking. In particular, the roles of repetitive stretches of side chains running the long axis of these {beta}-sheets, termed 'cross-strand ladders,' remain poorly characterized due to the inherently insoluble and heterogeneous nature of self-assemblies. To overcome these experimental challenges, we have established a complementary experimental system termed 'peptide self-assembly mimics' (PSAMs). The PSAMs capture a defined number of self-assembly-like peptide repeats within a soluble {beta}-rich protein, making structural and energetic studies possible. In this work, we investigated the role of cross-strand ladders containing aromatic residues, which are prominent in self-assembling peptides. A combination of solution data and high-resolution crystal structures revealed that a single cross-strand ladder consisting solely of Tyr significantly stabilized, rigidified, and flattened the PSAM {beta}-sheet. These characteristics would stabilize each {beta}-sheet layer of a self-assembly and direct sheet conformations compatible with lamination. Our results therefore provide a rationale for the abundance of aromatic amino acids in fibril-forming peptides and establish important roles of cross-strand Tyr ladders in the structure and stability of {beta}-rich peptide self-assemblies.

  16. High-speed assembly language (80386/80387) programming for laser spectra scan control and data acquisition providing improved resolution water vapor spectroscopy

    Science.gov (United States)

    Allen, Robert J.

    1988-01-01

    An assembly language program using the Intel 80386 CPU and 80387 math co-processor chips was written to increase the speed of data gathering and processing, and provide control of a scanning CW ring dye laser system. This laser system is used in high resolution (better than 0.001 cm-1) water vapor spectroscopy experiments. Laser beam power is sensed at the input and output of white cells and the output of a Fabry-Perot. The assembly language subroutine is called from Basic, acquires the data and performs various calculations at rates greater than 150 faster than could be performed by the higher level language. The width of output control pulses generated in assembly language are 3 to 4 microsecs as compared to 2 to 3.7 millisecs for those generated in Basic (about 500 to 1000 times faster). Included are a block diagram and brief description of the spectroscopy experiment, a flow diagram of the Basic and assembly language programs, listing of the programs, scope photographs of the computer generated 5-volt pulses used for control and timing analysis, and representative water spectrum curves obtained using these programs.

  17. Self-Assembled Upconversion Nanoparticle Clusters for NIR-controlled Drug Release and Synergistic Therapy after Conjugation with Gold Nanoparticles.

    Science.gov (United States)

    Cai, Huijuan; Shen, Tingting; Kirillov, Alexander M; Zhang, Yu; Shan, Changfu; Li, Xiang; Liu, Weisheng; Tang, Yu

    2017-05-01

    Fabricated three-dimensional (3D) upconversion nanoclusters (abbreviated as EBSUCNPs) are obtained via an emulsion-based bottom-up self-assembly of NaGdF4:Yb/Er@NaGdF4 nanoparticles (abbreviated as UCNPs), which comprise a NaGdF4:Yb/Er core and a NaGdF4 shell. The EBSUCNPs were then coated with a thin mesoporous amino-functionalized SiO2 shell (resulting in EBSUCNPs@SiO2 precursor) and further conjugated with gold nanoparticles to give the novel EBSUCNPs@SiO2@Au material. Finally, EBSUCNPs@SiO2@Au was applied as a biocompatible and efficient drug carrier for doxorubicin (DOX), thus giving rise to a multifunctional EBSUCNPs@SiO2-DOX@Au nanocomposite. This final material, EBSUCNPs@SiO2-DOX@Au, and the precursor nanoparticles, EBSUCNPs@SiO2@Au, were both fully characterized and their luminescence was investigated in detail. In addition, the drug release properties and photothermal effects of EBSUCNPs@SiO2-DOX@Au were also discussed. Interestingly, when under NIR irradiation, an increasing DOX release was achieved owing to the thermal effect of the Au NPs after absorbing the green light from the upconversion nanoclusters based on the fluorescence resonance energy transfer (FRET) effect. Thus, a near-infrared (NIR)-controlled "on-off" pattern of drug release behavior can be achieved. Moreover, compared with a single therapy method, the assembled nanocomposites exhibit a good synergistic therapy against cancer cells that combines chemotherapy with photothermal therapy. In addition, the in vitro fluorescence microscopy images of EBSUCNPs@SiO2-DOX@Au show a higher enhancement in the red region due to the loading of DOX molecules with respect to EBSUCNPs@SiO2@Au. Therefore, this novel multifunctional 3D cluster architecture can be used in the biomedical field after modification and may pave a new way in other application areas of UCNPs clusters.

  18. Synthesis, morphological control, dispersion stabilization and in situ self-assembly of noble metal nanostructures using multidentate resorcinarene surfactants

    Science.gov (United States)

    Han, Sangbum

    In this dissertation, a detailed investigation on the influence of various macrocyclic resorcinarene surfactants in determining the morphology, stabilization and self-assembly of mono- and bi- metallic nanoparticles was undertaken. (Abstract shortened by ProQuest.).

  19. The Interplay of the N- and C-Terminal Domains of MCAK Control Microtubule Depolymerization Activity and Spindle Assembly

    OpenAIRE

    Ems-McClung, Stephanie C.; Hertzer, Kathleen M.; Zhang, Xin; Miller, Mill W.; Walczak, Claire E.

    2007-01-01

    Spindle assembly and accurate chromosome segregation require the proper regulation of microtubule dynamics. MCAK, a Kinesin-13, catalytically depolymerizes microtubules, regulates physiological microtubule dynamics, and is the major catastrophe factor in egg extracts. Purified GFP-tagged MCAK domain mutants were assayed to address how the different MCAK domains contribute to in vitro microtubule depolymerization activity and physiological spindle assembly activity in egg extracts. Our biochem...

  20. Controlled self-assemblies of polystyrene-block-polydimethylsiloxane micelles in cylindrical confinement through a micelle solution wetting method and Rayleigh-instability-driven transformation.

    Science.gov (United States)

    Ko, Hao-Wen; Higuchi, Takeshi; Chang, Chun-Wei; Cheng, Ming-Hsiang; Isono, Komei; Chi, Mu-Huan; Jinnai, Hiroshi; Chen, Jiun-Tai

    2017-08-16

    Block copolymer micelles have been extensively discussed for many decades because of their applications, such as lithography and drug delivery. However, controlling the morphologies of nanostructure assembly using block copolymer micelles as building elements remains a great challenge. In this work, we developed a novel route to induce micelle assembly in confined geometries. Polystyrene-block-polydimethylsiloxane (PS-b-PDMS) micelle solutions were used to prepare micelle nanostructures, and the critical parameters affecting the morphologies were determined. Micelle nanorods, micelle nanospheres, and multi-component nanopeapods were prepared by wetting anodic aluminum oxide (AAO) templates with micelle solutions. Rayleigh-instability-driven transformation was discovered to play an important role in controlling the morphologies of the micelle nanostructures. This study not only proposes a versatile approach to preparing block copolymer micelle nanostructures, but it also provides deeper insight into the controlling factors of block copolymer micelle morphologies in cylindrical confinement.

  1. Controllable Assembly and Separation of Colloidal Nanoparticles through a One-Tube Synthesis Based on Density Gradient Centrifugation.

    Science.gov (United States)

    Qi, Xiaohan; Li, Minglin; Kuang, Yun; Wang, Cheng; Cai, Zhao; Zhang, Jin; You, Shusen; Yin, Meizhen; Wan, Pengbo; Luo, Liang; Sun, Xiaoming

    2015-05-04

    Self-assembly of gold nanoparticles into one-dimensional (1D) nanostructures with finite primary units was achieved by introducing a thin salt (NaCl) solution layer into density gradient before centrifugation. The electrostatic interactions between Au nanoparticles would be affected and cause 1D assembly upon passing through the salt layer. A negatively charged polymer such as poly(acrylic acid) was used as an encapsulation/stabilization layer to help the formation of 1D Au assemblies, which were subsequently sorted according to unit numbers at succeeding separation zones. A centrifugal field was introduced as the external field to overcome the random Brownian motion of NPs and benefit the assembly effect. Such a facile "one-tube synthesis" approach couples assembly and separation in one centrifuge tube by centrifuging once. The method can be tuned by changing the concentration of interference salt layer, encapsulation layer, and centrifugation rate. Furthermore, positively charged fluorescent polymers such as perylenediimide-poly(N,N-diethylaminoethyl methacrylate) could encapsulate the assemblies to give tunable fluorescence properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A highly controllable protein self-assembly system with morphological versatility induced by reengineered host-guest interactions.

    Science.gov (United States)

    Li, Xiumei; Bai, Yushi; Huang, Zupeng; Si, Chengye; Dong, Zeyuan; Luo, Quan; Liu, Junqiu

    2017-06-14

    Manipulating proteins to self-assemble into highly ordered nanostructures not only provides insights into the natural protein assembly process but also allows access to advanced biomaterials. Host-guest interactions have been widely used in the construction of artificial protein assemblies in recent years. CB[8] can selectively associate with two tripeptide Phe-Gly-Gly (FGG) tags with an extraordinarily high binding affinity (Kter = 1.5 × 10(11) M(-2)). However, the FGG tags utilized before are all fixed to the N-termini via genetic fusion; this spatial limitation greatly confined the availability of the CB[8]/FGG pair in the construction of more sophisticated protein nanostructures. Here we first designed and synthesized a maleimide-functionalized Phe-Gly-Gly tag as a versatile site-specific protein modification tool; this designed tag can site-selectively introduce desired guest moieties onto protein surfaces for host-guest driven protein assembly. When regulating the self-assembly process of proteins and CB[8], the constructed protein nanosystem can exhibit distinctive morphological diversities ranging from nanorings, nanospirals, nanowires to superwires. This work developed a new strategy for site-specific protein modification of the CB[8] binding tag and provides a possible direction for the construction of 'smart', dynamic self-assembly systems.

  3. A Method for Designing Assembly Tolerance Networks of Mechanical Assemblies

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    2012-01-01

    Full Text Available When designing mechanical assemblies, assembly tolerance design is an important issue which must be seriously considered by designers. Assembly tolerances reflect functional requirements of assembling, which can be used to control assembling qualities and production costs. This paper proposes a new method for designing assembly tolerance networks of mechanical assemblies. The method establishes the assembly structure tree model of an assembly based on its product structure tree model. On this basis, assembly information model and assembly relation model are set up based on polychromatic sets (PS theory. According to the two models, the systems of location relation equations and interference relation equations are established. Then, using methods of topologically related surfaces (TTRS theory and variational geometric constraints (VGC theory, three VGC reasoning matrices are constructed. According to corresponding relations between VGCs and assembly tolerance types, the reasoning matrices of tolerance types are also established by using contour matrices of PS. Finally, an exemplary product is used to construct its assembly tolerance networks and meanwhile to verify the feasibility and effectiveness of the proposed method.

  4. Design and verification of focal plane assembly thermal control system of one space-based astronomy telescope

    Science.gov (United States)

    Yang, Wen-gang; Fan, Xue-wu; Wang, Chen-jie; Wang, Ying-hao; Feng, Liang-jie; Du, Yun-fei; Ren, Guo-rui; Wang, Wei; Li, Chuang; Gao, Wei

    2015-10-01

    One space-based astronomy telescope will observe astronomy objects whose brightness should be lower than 23th magnitude. To ensure the telescope performance, very low system noise requirements need extreme low CCD operating temperature (lower than -65°C). Because the satellite will be launched in a low earth orbit, inevitable space external heat fluxes will result in a high radiator sink temperature (higher than -65°C). Only passive measures can't meet the focal plane cooling specification and active cooling technologies must be utilized. Based on detailed analysis on thermal environment of the telescope and thermal characteristics of focal plane assembly (FPA), active cooling system which is based on thermo-electric cooler (TEC) and heat rejection system (HRS) which is based on flexible heat pipe and radiator have been designed. Power consumption of TECs is dependent on the heat pumped requirements and its hot side temperature. Heat rejection capability of HRS is mainly dependent on the radiator size and temperature. To compromise TEC power consumption and the radiator size requirement, thermal design of FPA must be optimized. Parasitic heat loads on the detector is minimized to reduce the heat pumped demands of TECs and its power consumption. Thermal resistance of heat rejection system is minimized to reject the heat dissipation of TECs from the hot side to the radiator efficiently. The size and surface coating of radiator are optimized to compromise heat reject ion requirements and system constraints. Based on above work, transient thermal analysis of FPA is performed. FPA prototype model has been developed and thermal vacuum/balance test has been accomplished. From the test, temperature of key parts and working parameters of TECs in extreme cases have been acquired. Test results show that CCD can be controlled below -65°C and all parts worked well during the test. All of these verified the thermal design of FPA and some lessons will be presented in this

  5. Dynamic Simulation of the Water-steam System in Once-through Boilers - Sub-critical Power Boiler Case -

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seongil; Choi, Sangmin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2017-05-15

    The dynamics of a water-steam system in a once-through boiler was simulated based on the physics-based modeling approach, representing the system in response to large load change or scale disturbance simulations. The modeling considered the mass, energy conservation, and momentum equation in the water pipe and the focus was limited to the sub-critical pressure region. An evaporator tube modeling was validated against the reference data. A simplified boiler system consisting of economizer, evaporator, and superheater was constructed to match a 500 MW power boiler. The dynamic response of the system following a disturbance was discussed along with the quantitative response characteristics. The dynamic response of the boiler system was further evaluated by checking the case of an off-design point operation of the feedwater-to-fuel supply ratio. The results re-emphasized the significance of controlling the feedwater-to-fuel supply ratio and additional design requirements of the water-steam separator and spray attemperator.

  6. Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

    Science.gov (United States)

    Wei, R. P.; Klier, K.; Simmons, G. W.; Chornet, E.

    1973-01-01

    Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

  7. Thermodynamic versus kinetic control in self-assembly of zero-, one-, quasi-two-, and two-dimensional metal-organic coordination structures

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tao; Wu, Qi; Shi, Ziliang; Lin, Nian [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong (China); Liu, Jun; Liu, Pei Nian [Shanghai Key Laboratory of Functional Materials Chemistry and Institute of Fine Chemicals, East China University of Science and Technology, Meilong Road 130, Shanghai (China)

    2015-03-14

    Four types of metal-organic structures exhibiting specific dimensionality were studied using scanning tunneling microscopy and Monte Carlo simulations. The four structures were self-assembled out of specifically designed molecular building blocks via the same coordination motif on an Au(111) surface. We found that the four structures behaved differently in response to thermal annealing treatments: The two-dimensional structure was under thermodynamic control while the structures of lower dimension were under kinetic control. Monte Carlo simulations revealed that the self-assembly pathways of the four structures are associated with the characteristic features of their specific heat. These findings provide insights into how the dimensionality of supramolecular coordination structures affects their thermodynamic properties.

  8. Septipyridines as conformationally controlled substitutes for inaccessible bis(terpyridine-derived oligopyridines in two-dimensional self-assembly

    Directory of Open Access Journals (Sweden)

    Daniel Caterbow

    2011-07-01

    Full Text Available The position of the peripheral nitrogen atoms in bis(terpyridine-derived oligopyridines (BTPs has a strong impact on their self-assembly behavior at the liquid/HOPG (highly oriented pyrolytic graphite interface. The intermolecular hydrogen bonding interactions in these peripheral pyridine units show specific 2D structures for each BTP isomer. From nine possible constitutional isomers only four have been described in the literature. The synthesis and self-assembling behavior of an additional isomer is presented here, but the remaining four members of the series are synthetically inaccessible. The self-assembling properties of three of the missing four BTP isomers can be mimicked by making use of the energetically preferred N–C–C–N transoid conformation between 2,2'-bipyridine subunits in a new class of so-called septipyridines. The structures are investigated by scanning tunneling microscopy (STM and a combination of force-field and first-principles electronic structure calculations.

  9. Discharge Computation of Trapezoidal Side Weir in Subcritical Flow Regime Using Conventional Weir Theory

    Directory of Open Access Journals (Sweden)

    S. Riahi

    2016-02-01

    Full Text Available Introduction: Side weir structures are extensively used in hydraulic engineering, irrigation and environmental engineering, and it usually consists of a main weir and a lateral channel. Side weirs are also used as an emergency structure. This structure is installed on one side or both sides of the main channel to divert the flow from the main channel to the side channel. Lateral outflow takes place when the water surface in the main channel rises above the weir sill. Flow over a side weir is a typical case of spatially varied flow with decreasing discharge. There have been extensive studies on side weir overflows. Most of the previous theoretical analysis and experimental research works are related to the flow over rectangular side weirs in rectangular main channels. In the current study, the flow conditions over a trapezoidal side weir located in a rectangular main channel in subcritical flow regime is considered. Materials and Methods: The experiments were performed in a rectangular open channel having provisions for a side weir at one side of the channel. The main channel was horizontal with 12 m length, 0.25 m width, and 0.5 m height, and it was installed on a frame; lateral channel that has a length of 6 m, width of 0.25 m, and height of 1 m. It was set up parallel to the main channel; walls and its bed were made up of Plexiglas plates. The side weir was positioned at a distance of 6 m from the channel’s entrance. A total of 121 experiments on trapezoidal side weirs were carried out. Results and Discussion: For trapezoidal side weir, effective non-dimensionnal parameters were identified using dimensional analysis and Buckingham's Pi-Theorem. Finally, the following non-dimensional parameters were considered as the most effective ones on the discharge coefficient of the trapezoidal side weir flow. in which Fr1= upstream Froude number, P= hight of the trapezoidal side weir, y1= upstream water depth, z=side slope of the trapezoidal side weir

  10. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev, E-mail: dcc@unr.edu

    2017-05-15

    Highlights: • Mixtures of oxides containing Ni, Fe, Cr and Nb formed on the surface. • Short term exposure tests observed breakdown of native film. • Formation of a Fe rich oxide layer on Inconel 718 prevents mass loss. - Abstract: Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO{sub 4}{sup 2−} based film formed; however minor quantities of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel. The surface films on both alloys were identified as NiFe{sub 2}O{sub 4} when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  11. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Science.gov (United States)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev

    2017-05-01

    Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO42- based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  12. Criticality Calculations of Fresh LEU and MOX Assemblies for Transport and Storage at the Balakovo Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Goluoglu, S.

    2001-01-11

    Transportation of low-enriched uranium (LEU) and mixed-oxide (MOX) assemblies to and within the VVER-1000-type Balakovo Nuclear Power Plant is investigated. Effective multiplication factors for fresh fuel assemblies on the railroad platform, fresh fuel assemblies in the fuel transportation vehicle, and fresh fuel assemblies in the spent fuel storage pool are calculated. If there is no absorber between the units, the configurations with all MOX assemblies result in higher effective multiplication factors than the configurations with all LEU assemblies when the system is dry. When the system is flooded, the configurations with all LEU assemblies result in higher effective multiplication factors. For normal operating conditions, effective multiplication factors for all configurations are below the presumed upper subcritical limit of 0.95. For an accident condition of a fully loaded fuel transportation vehicle that is flooded with low-density water (possibly from a fire suppression system), the presumed upper subcritical limit is exceeded by configurations containing LEU assemblies.

  13. Numerical simulations of flow field in the target region of accelerator-driven subcritical reactor system

    CERN Document Server

    Chen Hai Yan

    2002-01-01

    Numerical simulations of flow field were performed by using the PHOENICS 3.2 code for the proposed spallation target of accelerator-driven subcritical reactor system (ADS). The fluid motion in the target is axisymmetric and is treated as a 2-D steady-state problem. A body-fitted coordinate system (BFC) is then chosen and a two-dimensional mesh of the flow channel is generated. Results are presented for the ADS target under both upward and downward flow, and for the target with diffuser plate installed below the window under downward flow

  14. Study on design of superconducting proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Xu Tao Guang

    2002-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac (SCL) is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. It is constitute by a series of the superconducting accelerating cavities. The cavity geometry is determined by means of the electromagnetic field computation. The SCL main parameters are determined by the particle dynamics computation

  15. Subcritical experiments at the FREYA experiment; Experimentos subcriticos en el proyecto FREYA

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.; Villamarin fernandez, D.

    2013-07-01

    The FREYA Project of the 7th Framework Program is aimed to the study of the kinetics of subcritical reactors coupled to an external neutron source, and, more specifically, to the validation of reactivity monitoring techniques. CIEMAT activities within the frame of this project have consisted in analyzing the possible ways of correcting the spatial and energy effects on these reactivity monitoring techniques, as well as analyzing the effects that may have on them the presence of different materials in the reflector and the position of the neutron source.

  16. Ion acoustic wave generation by a standing electromagnetic field in a subcritical plasma

    OpenAIRE

    P. Fischer; Gauthereau, C.; Godiot, J.; G. Matthieussent

    1987-01-01

    An electromagnetic wave ( f = 9 GHz, Pi = 150 kW, τ = 1.5 μs) is launched into a subcritical argon plasma (n e ≃1011 cm-3, P0 ≃ 5 × 10-4 Torr), resulting in a standing wave. The associated ponderomotive force generates an ion acoustic wave with a wave vector equal to twice the electromagnetic one and with a frequency satisfying the usual dispersion relation (fA ≃ 150 kHz). The main features of the ion acoustic wave, as measured in this 3D experiment, agree with a simple theory. However, varyi...

  17. PRACTICAL APPLICATION OF THE SINGLE-PARAMETER SUBCRITICAL MASS LIMIT FOR PLUTONIUM METAL

    Energy Technology Data Exchange (ETDEWEB)

    MITCHELL, MARK VON [Los Alamos National Laboratory

    2007-01-10

    According to ANS-8.1, operations with fissile materials can be performed safely by complying with any of the listed single-parameter subcritical limits. For metallic units, when interspersed moderators are present, the mass limits apply to a single piece having no concave surfaces. On a practical level, when has any operation with fissile metal involved a single piece and absolutely no moderating material, e.g., water, oil, plastic, etc.? This would be rare. This paper explores the application of the single-parameter plutonium metal mass limit for realistic operational environments.

  18. Hydrothermal liquefaction of Spirulina and Nannochloropsis Salina under subcritical and supercritical water conditions

    DEFF Research Database (Denmark)

    Toor, Saqib; Reddy, H.; Deng, S.

    2013-01-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220-375 °C, 20-255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid...... on Nannochloropsis salina at 350 °C and 175 bar. For Spirulina platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for Nannochloropsis salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae...

  19. Semiclassical Limit of the Non-linear Schroedinger-Poisson Equation With Subcritical Initial Data

    Science.gov (United States)

    2002-12-01

    lim ∇xargψ. As noted earlier, this argument is self - consistent as long as the solution of the Euler- Poisson system (1.5)-(1.6) remains classical...00-2003 to 00-00-2003 4. TITLE AND SUBTITLE Semiclassical Limit of the Non-linear Schrodinger - Poisson Equation with Subcritical Initial Data 5a...classical limit of a self - consistent quantum-Vlasov equation in 3-D, Math. Models Methods Appl. Sci., 3 (1993), pp. 109–124. [SMM] C. Sparber, P. Markowich

  20. Supramolecular synthons on surfaces : Controlling dimensionality and periodicity of tetraarylporphyrin assemblies by the interplay of cyano and alkoxy substituents

    NARCIS (Netherlands)

    Wintjes, Nikolai; Hornung, Jens; Lobo-Checa, Jorge; Voigt, Tobias; Samuely, Tomáš; Thilgen, Carlo; Stöhr, Meike; Diederich, François; Jung, Thomas A.

    2008-01-01

    The self-assembly of three porphyrin derivatives was studied in detail on a Cu(111) substrate by means of scanning tunneling microscopy (STM). All derivatives have two 4-cyanophenyl substituents in diagonally opposed meso-positions of the porphyrin core. but differ in the nature of the other two

  1. Surface self-assembled hybrid nanocomposites with electroactive nanoparticles and enzymes confined in a polymer matrix for controlled electrocatalysis

    DEFF Research Database (Denmark)

    Zhu, Nan; Ulstrup, Jens; Chi, Qijin

    2015-01-01

    A three-dimensional network of highly branched poly(ethyleneimine) (PEI) is designed and synthesized on gold electrode surfaces. A self-assembled monolayer (SAM) of dithiobis(succinimidyl propionate) (DTSP) on a gold electrode was first prepared, which is confirmed by the reductive desorption of Au...

  2. The glass transition in a nutshell: a source of inspiration to describe the subcritical transition to turbulence.

    Science.gov (United States)

    Dauchot, Olivier; Bertin, Eric

    2014-04-01

    The starting point of the present work is the observation of possible analogies, both at the phenomenological and at the methodological level, between the subcritical transition to turbulence and the glass transition. Having recalled the phenomenology of the subcritical transition to turbulence, we review the theories of the glass transition at a very basic level, focusing on the history of their development as well as on the concepts they have elaborated. Doing so, we aim at attracting the attention on the above-mentioned analogies, which we believe could inspire new developments in the theory of the subcritical transition to turbulence. We then briefly describe a model inspired by one of the simplest and most inspiring models of the glass transition, the so-called Random Energy Model, as a first step in that direction.

  3. Applications of subcritical and supercritical water conditions for extraction, hydrolysis, gasification, and carbonization of biomass: a critical review

    Directory of Open Access Journals (Sweden)

    D. Lachos-Perez

    2017-06-01

    Full Text Available This review summarizes the recent essential aspects of subcritical and supercritical water technology applied tothe extraction, hydrolysis, carbonization, and gasification processes. These are clean and fast technologies which do not need pretreatment, require less reaction time, generate less corrosion and residues, do not usetoxic solvents, and reduce the synthesis of degradation byproducts. The equipment design, process parameters, and types of biomass used for subcritical and supercritical water process are presented. The benefits of catalysis to improve process efficiency are addressed. Bioactive compounds, reducing sugars, hydrogen, biodiesel, and hydrothermal char are the final products of subcritical and supercritical water processes. The present review also revisits advances of the research trends in the development of subcriticaland supercritical water process technologies.

  4. Simulator for an Accelerator-Driven Subcritical Fissile Solution System

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Day, Christy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Determan, John C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-14

    LANL has developed a process to generate a progressive family of system models for a fissile solution system. This family includes a dynamic system simulation comprised of coupled nonlinear differential equations describing the time evolution of the system. Neutron kinetics, radiolytic gas generation and transport, and core thermal hydraulics are included in the DSS. Extensions to explicit operation of cooling loops and radiolytic gas handling are embedded in these systems as is a stability model. The DSS may then be converted to an implementation in Visual Studio to provide a design team the ability to rapidly estimate system performance impacts from a variety of design decisions. This provides a method to assist in optimization of the system design. Once design has been generated in some detail the C++ version of the system model may then be implemented in a LabVIEW user interface to evaluate operator controls and instrumentation and operator recognition and response to off-normal events. Taken as a set of system models the DSS, Visual Studio, and LabVIEW progression provides a comprehensive set of design support tools.

  5. Controlling Heat Release from a Close-Packed Bisazobenzene-Reduced-Graphene-Oxide Assembly Film for High-Energy Solid-State Photothermal Fuels.

    Science.gov (United States)

    Zhao, Xiaoze; Feng, Yiyu; Qin, Chengqun; Yang, Weixiang; Si, Qianyu; Feng, Wei

    2017-04-10

    A closed-cycle system for light-harvesting, storage, and heat release is important for utilizing and managing renewable energy. However, combining a high-energy, stable photochromic material with a controllable trigger for solid-state heat release remains a great challenge for developing photothermal fuels (PTFs). This paper presents a uniform PTF film fabricated by the assembly of close-packed bisazobenzene (bisAzo) grafted onto reduced graphene oxide (rGO). The assembled rGO-bisAzo template exhibited a high energy density of 131 Wh kg-1 and a long half-life of 37 days owing to inter- or intramolecular H-bonding and steric hindrance. The rGO-bisAzo PTF film released and accumulated heat to realize a maximum temperature difference (DT) of 15 °C and a DT of over 10 °C for 30 min when the temperature difference of the environment was greater than100 °C. Controlling heat release in the solid-state assembly paves the way to develop highly efficient and high-energy PTFs for a multitude of applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Final Progress Report: FRACTURE AND SUBCRITICAL DEBONDING IN THIN LAYERED STRUCTURES: EXPERIMENTS AND MULTI-SCALE MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Reinhold H. Dauskardt

    2005-08-30

    Final technical report detailing unique experimental and multi-scale computational modeling capabilities developed to study fracture and subcritical cracking in thin-film structures. Our program to date at Stanford has studied the mechanisms of fracture and fatigue crack-growth in structural ceramics at high temperature, bulk and thin-film glasses in selected moist environments where we demonstrated the presence of a true mechanical fatigue effect in some glass compositions. We also reported on the effects of complex environments and fatigue loading on subcritical cracking that effects the reliability of MEMS and other micro-devices using novel micro-machined silicon specimens and nanomaterial layers.

  7. Anion-controlled assembly of metal 3,5-bis(benzimidazol-1-ylmethyl) benzoate complexes: Synthesis, characterization and property

    Energy Technology Data Exchange (ETDEWEB)

    Kuai, Hai-Wei [Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); Faculty of Life Science and Chemical Engineering, Huaiyin Institute of Technology, Huaian 223003 (China); Lv, Gao-Chao; Hou, Chao [Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); Sun, Wei-Yin, E-mail: sunwy@nju.edu.cn [Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-03-15

    Hydrothermal reactions of 3,5-bis(benzimidazol-1-ylmethyl)benzoic acid (HL) with Cd(II), Cu(II) and Zn(II) salts provide eight new metal complexes which were characterized by single crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. Two cadmium frameworks [Cd(L){sub 2}]·2H{sub 2}O (1) and [Cd(L)Cl] (2) have 3D structures with (4{sup 2}.6{sup 5}.8{sup 3})(4{sup 2}.6) and rtl (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 10}.8{sup 3}) topologies, respectively. Structural diversity of four copper complexes [Cu{sub 3}(L){sub 2}]·NO{sub 3}·0.5H{sub 2}O (3), [Cu{sub 2}(HL){sub 2}(SO{sub 4})]·3.5H{sub 2}O (4), [Cu(L)(bdc){sub 0.5}]·1.5H{sub 2}O (5) and [Cu{sub 2}(L)(HL)(Hbdc)] (6) (H{sub 2}bdc=1,4-benzenedicarboxylic acid) is achieved through the alteration of copper salts and addition of auxiliary ligand. As a result, 3 has a 1D ladder structure, 4 is a discrete dinuclear complex, 5 displays a (3,4)-connected 2-nodal 3-fold interpenetrating framework with (4{sup 2}.6.10{sup 2}.12)(4{sup 2}.6) topology, 6 exhibits a 4-connected uninodal 2D sql (4{sup 4}.6{sup 2}) network. Within the zinc series, ZnCl{sub 2} and ZnSO{sub 4} were used for the syntheses of [Zn(L)Cl] (7) and [Zn(L)(SO{sub 4}){sub 0.5}]·2H{sub 2}O (8), respectively. 7 shows a 3-connected uninodal 2D hcb network with (6{sup 3}) topology and 8 is a (3,6)-connected 2-nodal 3D framework with (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 8}.10) topology. The luminescent properties of the Cd(II) and Zn(II) complexes were investigated. - Graphical abstract: Eight new complexes have been successfully synthesized from the hydrothermal reactions of Cd(II), Cu(II) and Zn(II) salts with 3,5-bis(benzimidazol-1-ylmethyl)benzoic acid. The complexes exhibited anion-controlled structural diversity. - Highlights: • Metal complexes have diverse structures of 1D chains, 2D networks and 3D frameworks. • Anion-controlled assembly of the complexes is reported. • The luminescent properties of the Cd

  8. Vacuum ultraviolet spectroscopy of the lowest-lying electronic state in subcritical and supercritical water.

    Science.gov (United States)

    Marin, Timothy W; Janik, Ireneusz; Bartels, David M; Chipman, Daniel M

    2017-05-17

    The nature and extent of hydrogen bonding in water has been scrutinized for decades, including how it manifests in optical properties. Here we report vacuum ultraviolet absorption spectra for the lowest-lying electronic state of subcritical and supercritical water. For subcritical water, the spectrum redshifts considerably with increasing temperature, demonstrating the gradual breakdown of the hydrogen-bond network. Tuning the density at 381 °C gives insight into the extent of hydrogen bonding in supercritical water. The known gas-phase spectrum, including its vibronic structure, is duplicated in the low-density limit. With increasing density, the spectrum blueshifts and the vibronic structure is quenched as the water monomer becomes electronically perturbed. Fits to the supercritical water spectra demonstrate consistency with dimer/trimer fractions calculated from the water virial equation of state and equilibrium constants. Using the known water dimer interaction potential, we estimate the critical distance between molecules (ca. 4.5 Å) needed to explain the vibronic structure quenching.

  9. Homoclinic connections and subcritical Neimark bifurcation in a duopoly model with adaptively adjusted productions

    Energy Technology Data Exchange (ETDEWEB)

    Agliari, Anna [Dipartimento di Scienze Economiche e Sociali, Universita Cattolica del Sacro Cuore, Via Emilia Parmense, 84, 29100 Piacenza (Italy)]. E-mail: anna.agliari@unicatt.it

    2006-08-15

    In this paper we study some global bifurcations arising in the Puu's oligopoly model when we assume that the producers do not adjust to the best reply but use an adaptive process to obtain at each step the new production. Such bifurcations cause the appearance of a pair of closed invariant curves, one attracting and one repelling, this latter being involved in the subcritical Neimark bifurcation of the Cournot equilibrium point. The aim of the paper is to highlight the relationship between the global bifurcations causing the appearance/disappearance of two invariant closed curves and the homoclinic connections of some saddle cycle, already conjectured in [Agliari A, Gardini L, Puu T. Some global bifurcations related to the appearance of closed invariant curves. Comput Math Simul 2005;68:201-19]. We refine the results obtained in such a paper, showing that the appearance/disappearance of closed invariant curves is not necessarily related to the existence of an attracting cycle. The characterization of the periodicity tongues (i.e. a region of the parameter space in which an attracting cycle exists) associated with a subcritical Neimark bifurcation is also discussed.

  10. Total acid number reduction kinetics of naphthenic acids using non-catalytic subcritical methanol

    Science.gov (United States)

    Zafar, Faisal; Mandal, Pradip Chandra; Shaari, Ku Zilati bt Ku; Nadeem, Saad

    2017-10-01

    Naphthenic acids (NAs) are weak organic acids present in the heavy crude oil and Oil Sand Bitumens. Whereas, the NAs are the major cause of corrosion in different processing, handling and storage equipment's of the refinery. Esterification of these acids can be an interesting method to reduce the NAs content in the crude oil besides its esters are valuable commodity and can be used as added lubricant in the oils. In this study, NAs reduction kinetics were investigated in a batch type reactor with subcritical methanol, the experiments were performed at temperatures of 150-210°C and fixed methanol partial pressure of 2 MPa. Findings of this study demonstrate that the 59% of total acid number (TAN) reduction was achieved at the temperature of 210°C, methanol partial pressure of 2 MPa and reaction time of 150 min. The TAN reduction followed second order kinetics with activation energy and frequency factor of 54.15 KJ/mol and 7.6×103, respectively. These results suggest that subcritical methanol can be an effective to reduce the TAN non-catalytically.

  11. Kinetics and reaction pathways of total acid number reduction of cyclopentane carboxylic acid using subcritical methanol

    Directory of Open Access Journals (Sweden)

    Mandal Pradip C.

    2016-09-01

    Full Text Available Cyclopentane carboxylic acid (CPCA is a model compound of Naphthenic acids (NAs. This objective of this paper is to discover total acid number (TAN reduction kinetics and pathways of the reaction between CAPA and subcritical methanol (SubC-MeOH. The experiments were carried out in an autoclave reactor at temperatures of 180-220°C, a methanol partial pressure (MPP of 3 MPa, reaction times of 0-30 min and CPCA initial gas phase concentrations of 0.016-0.04 g/mL. TAN content of the samples were analyzed using ASTM D 974 techniques. The reaction products were identified and quantified with the help of GC/MS and GC-FID respectively. Experimental results reveal that TAN removal kinetics followed first order kinetics with an activation energy of 13.97 kcal/mol and a pre-exponential factor of 174.21 s-1. Subcritical methanol is able to reduce TAN of CPCA decomposing CPCA into new compounds such as cyclopentane, formaldehyde, methyl acetate and 3-pentanol.

  12. Subcritical saturation of the magnetorotational instability through mean magnetic field generation

    Science.gov (United States)

    Xie, Jin-Han; Julien, Keith; Knobloch, Edgar

    2018-03-01

    The magnetorotational instability is widely believed to be responsible for outward angular momentum transport in astrophysical accretion discs. The efficiency of this transport depends on the amplitude of this instability in the saturated state. We employ an asymptotic expansion based on an explicit, astrophysically motivated time-scale separation between the orbital period, Alfvén crossing time and viscous or resistive dissipation time-scales, originally proposed by Knobloch and Julien, to formulate a semi-analytical description of the saturated state in an incompressible disc. In our approach a Keplerian shear flow is maintained by the central mass but the instability saturates via the generation of a mean vertical magnetic field. The theory assumes that the time-averaged angular momentum flux and the radial magnetic flux are constant and determines both self-consistently. The results predict that, depending on parameters, steady saturation may be supercritical or subcritical, and in the latter case that the upper (lower) solution branch is always stable (unstable). The angular momentum flux is always outward, consistent with the presence of accretion, and for fixed wavenumber peaks in the subcritical regime. The limit of infinite Reynolds number at large but finite magnetic Reynolds number is also discussed.

  13. Ultrasound-Enhanced Subcritical CO2 Extraction of Lutein from Chlorella pyrenoidosa.

    Science.gov (United States)

    Fan, Xiao-Dan; Hou, Yan; Huang, Xing-Xin; Qiu, Tai-Qiu; Jiang, Jian-Guo

    2015-05-13

    Lutein is an important pigment of Chlorella pyrenoidosa with many beneficial functions in human health. The main purpose of this study was to extract lutein from C. pyrenoidosa using ultrasound-enhanced subcritical CO2 extraction (USCCE). Effects of operating conditions on the extraction, including extraction pretreatment, temperature, pressure, time, CO2 flow rate, and ultrasonic power, were investigated, and an orthogonal experiment was designed to study the effects of extraction pressure, temperature, cosolvent amount, and time on the extraction yields. The USCCE method was compared with other extraction methods in terms of the yields of lutein and the microstructure of C. pyrenoidosa powder by scanning electron microscopy. A maximal extraction yield of 124.01 mg lutein/100 g crude material was achieved under optimal conditions of extraction temperature at 27 °C, extraction pressure at 21 MPa, cosolvent amount at 1.5 mL/g ethanol, and ultrasound power at 1000 W. Compared to other methods, USCCE could significantly increase the lutein extraction yield at lower extraction temperature and pressure. Furthermore, the kinetic models of USCCE and subcritical CO2 extraction (SCCE) of lutein from C. pyrenoidosa were set as E = 130.64 × (1 - e(-0.6599t)) and E = 101.82 × (1 - e(-0.5683t)), respectively. The differences of parameters in the kinetic models indicate that ultrasound was able to enhance the extraction process of SCCE.

  14. Optimization of Subcritical Water Extraction of Resveratrol from Grape Seeds by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Yajie Tian

    2017-03-01

    Full Text Available The subcritical water extraction (SWE is a high-efficiency and environment-friendly extraction method. The extraction of resveratrol (RES of grape seeds obtained from the wine production process was proposed using subcritical water extraction (SWE. The effects of different extraction process parameters on RES yield were investigated by single factors. Extraction optimization was conducted using response surface methodology (RSM. Extraction temperature was proven to be the most significant factor influencing RES yield. The optimal conditions was as follows: extraction pressure of 1.02 MPa, temperature of 152.32 °C, time of 24.89 min, and a solid/solvent ratio of 1:15 g/mL. Under these optimal conditions, the predicted extraction RES yield was 6.90 μg/g and the recoveries was up to 91.98%. Compared to other previous studies, this method required less pollution and less treatment time to extract RES from grape seeds. From these results, added economic value to this agroindustrial residue is proposed using environmentally friendly extraction techniques.

  15. Release of phenolic acids from defatted rice bran by subcritical water treatment.

    Science.gov (United States)

    Fabian, Cynthia; Tran-Thi, Ngoc Yen; Kasim, Novy S; Ju, Yi-Hsu

    2010-12-01

    Oil production from rice bran, an undervalued by-product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV-B-protecting and anti-tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. Analysis of total phenolics using Folin-Ciocalteu reagent showed about 2-20 g gallic acid equivalent kg(-1) bran in the extracts. High-performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4-2 g kg(-1) bran). Ferulic, p-coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p-coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry.

  16. Pilot-scale subcritical solvent extraction of curcuminoids from Curcuma long L.

    Science.gov (United States)

    Kwon, Hye-Lim; Chung, Myong-Soo

    2015-10-15

    Curcuminoids consisted curcumin, demethoxycurcumin and bisdemethoxycurcumin, were extracted from turmeric using subcritical solvent by varying conditions of temperature (110-150 °C), time (1-10 min), pressure (5-100 atm), solid-to-solvent ratio, and mixing ratio of solvent. Preliminary lab-scale experiments were conducted to determine the optimum extraction temperature and mixing ratio of water and ethanol for the pilot-scale extraction. The maximum yield of curcuminoids in the pilot-scale system was 13.58% (curcumin 4.94%, demethoxycurcumin 4.73%, and bisdemethoxycurcumin 3.91% in dried extracts) at 135 °C/5 min with water/ethanol mixture (50:50, v/v) as a solvent. On the other hand, the extraction yields of curcuminoids were obtained as 10.49%, 13.71% and 13.96% using the 50%, 95% and 100% ethanol, respectively, at the atmospheric condition (60 °C/120 min). Overall results showed that the subcritical solvent extraction is much faster and efficient extraction method considering extracted curcuminoids contents and has a potential to develop a commercial process for the extraction of curcuminoids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements

    Science.gov (United States)

    van Wyk, F.; Highcock, E. G.; Field, A. R.; Roach, C. M.; Schekochihin, A. A.; Parra, F. I.; Dorland, W.

    2017-11-01

    We investigate the effect of varying the ion temperature gradient (ITG) and toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer core of MAST by means of local gyrokinetic simulations. We show that nonlinear simulations reproduce the experimental ion heat flux and that the experimentally measured values of the ITG and the flow shear lie close to the turbulence threshold. We demonstrate that the system is subcritical in the presence of flow shear, i.e., the system is formally stable to small perturbations, but transitions to a turbulent state given a large enough initial perturbation. We propose that the transition to subcritical turbulence occurs via an intermediate state dominated by low number of coherent long-lived structures, close to threshold, which increase in number as the system is taken away from the threshold into the more strongly turbulent regime, until they fill the domain and a more conventional turbulence emerges. We show that the properties of turbulence are effectively functions of the distance to threshold, as quantified by the ion heat flux. We make quantitative comparisons of correlation lengths, times, and amplitudes between our simulations and experimental measurements using the MAST BES diagnostic. We find reasonable agreement of the correlation properties, most notably of the correlation time, for which significant discrepancies were found in previous numerical studies of MAST turbulence.

  18. Production of valued materials from squid viscera by subcritical water hydrolysis.

    Science.gov (United States)

    Uddin, M Salim; Ahn, Hyang-Min; Kishimura, Hideki; Chun, Byung-Soo

    2010-09-01

    Subcritical water hydrolysis was carried out to produce valued materials from squid viscera, the waste product of fish processing industries. The reaction temperatures for hydrolysis of rawand deoiled squid viscera were maintained from 180 to 280 degrees C for5 min. The ratio of material to water forhydrolysis was 1:50. Most of the proteins from deoiled squid viscera were recovered at high temperature. The protein yield in raw squid viscera hydrolyzate decreased with the rise of temperature. The reducing sugar yield was higher at high temperature in subcritical water hydrolysis of both raw and deoiled squid viscera. The highest yield of amino acids in raw and deoiled squid viscera hydrolyzates were 233.25 +/- 3.25 and 533.78 +/- 4.13 mg g(-1) at 180 and 280 degrees C, respectively. Most amino acids attained highest yield at the reaction temperature range of 180-220 degrees C and 260-280 degrees C for raw and deoiled samples, respectively. The recovery of amino acids from deoiled squid viscera was about 1.5 times higher than that of raw squid viscera.

  19. Subcritical convection in a rapidly rotating sphere at low Prandtl number

    CERN Document Server

    Guervilly, Celine

    2016-01-01

    We study non-linear convection in a low Prandtl number fluid ($Pr = 0.01-0.1$) in a rapidly rotating sphere with internal heating. We use a numerical model based on the quasi-geostrophic approximation, in which variations of the axial vorticity along the rotation axis are neglected, whereas the temperature field is fully three-dimensional. We identify two separate branches of convection close to onset: (i) a well-known weak branch for Ekman numbers greater than $10^{-6}$, which is continuous at the onset (supercritical bifurcation) and consists of a superposition of thermal Rossby waves, and (ii) a novel strong branch at lower Ekman numbers, which is discontinuous at the onset. The strong branch becomes subcritical for Ekman numbers of the order of $10^{-8}$. On the strong branch, the Reynolds number of the flow is greater than $10^3$, and a strong zonal flow with multiple jets develops, even close to the non-linear onset of convection. We find that the subcriticality is amplified by decreasing the Prandtl nu...

  20. Subcritical Thermal Convection of Liquid Metals in a Rapidly Rotating Sphere

    Science.gov (United States)

    Kaplan, E. J.; Schaeffer, N.; Vidal, J.; Cardin, P.

    2017-09-01

    Planetary cores consist of liquid metals (low Prandtl number Pr) that convect as the core cools. Here, we study nonlinear convection in a rotating (low Ekman number Ek) planetary core using a fully 3D direct numerical simulation. Near the critical thermal forcing (Rayleigh number Ra), convection onsets as thermal Rossby waves, but as Ra increases, this state is superseded by one dominated by advection. At moderate rotation, these states (here called the weak branch and strong branch, respectively) are smoothly connected. As the planetary core rotates faster, the smooth transition is replaced by hysteresis cycles and subcriticality until the weak branch disappears entirely and the strong branch onsets in a turbulent state at Ek <10-6. Here, the strong branch persists even as the thermal forcing drops well below the linear onset of convection (Ra =0.7 Racrit in this study). We highlight the importance of the Reynolds stress, which is required for convection to subsist below the linear onset. In addition, the Péclet number is consistently above 10 in the strong branch. We further note the presence of a strong zonal flow that is nonetheless unimportant to the convective state. Our study suggests that, in the asymptotic regime of rapid rotation relevant for planetary interiors, thermal convection of liquid metals in a sphere onsets through a subcritical bifurcation.

  1. Self-assembled particles of N-phthaloylchitosan-g-polycaprolactone molecular bottle brushes as carriers for controlled release of indometacin.

    Science.gov (United States)

    Huang, Youju; Li, Liangbin; Fang, Yue'e

    2010-02-01

    A series of amphiphilic N-phthaloylchitosan-g-polycaprolactone molecular bottle brushes were prepared by "graft onto" method. The narrow distribution of polycaprolactone macromonomers ensures that the molecular bottle brushes can self-assemble into highly monodisperse particles, which have the ability to get a high loading efficiency of the hydrophobic drug, indometacin (INN). Searching for the effective drug loading ratio, three parameters such as polycaprolactone chain length, the grafting content and concentration of the molecular bottle brushes were tested to entrap INN. These encapsulated drug particles show sustained release of the encapsulated INN, of which 91.7% was released in 22 h at 37 degrees C in phosphate buffered saline. The self-assembled particles of the molecular bottle brushes as carriers for INN can effectively prevent the drug from releasing quickly and prolong the release time, which is a promising candidate for potential clinical applications.

  2. Benzo(a)pyrene accumulation in soils of technogenic emission zone by subcritical water extraction method

    Science.gov (United States)

    Sushkova, Svetlana; Minkina, Tatiana; Kizilkaya, Ridvan; Mandzhieva, Saglara; Batukaev, Abdulmalik; Bauer, Tatiana; Gulser, Coskun

    2016-04-01

    The purpose of research is the assessment of main marker of polycyclic aromatic hydrocarbons contamination, benzo[a]pyrene (BaP) content in soils of emission zone of the power complex plant in soils with use of ecologically clean and effective subcritical water extraction method. Studies were conducted on the soils of monitoring plots subjected to Novocherkassk Power Plant emissions from burning coal. In 2000, monitoring plots were established at different distances from the NPS (1.0-20.0 km). Soil samples for the determination of soil properties and the contents of BaP were taken from a depth of 0-20 cm. The soil cover in the region under study consisted of ordinary chernozems, meadow-chernozemic soils, and alluvial meadow soils. This soil revealed the following physical and chemical properties: Corg-3.1-5.0%, pH-7.3-7.6, ECE-31.2-47.6 mmol(+)/100g; CaCO3-0.2-1.0%, the content of physical clay - 51-67% and clay - 3-37%. BaP extraction from soils was carried out by a subcritical water extraction method. Subcritical water extraction of BaP from soil samples was conducted in a specially developed extraction cartridge made of stainless steel and equipped with screw-on caps at both ends. It was also equipped with a manometer that included a valve for pressure release to maintain an internal pressure of 100 atm. The extraction cartridge containing a sample and water was placed into an oven connected to a temperature regulator under temperature 250oC and pressure 60 atm. The BaP concentration in the acetonitrile extract was determined by HPLC. The efficiency of BaP extraction from soil was determined using a matrix spike. The main accumulation of pollutant in 20 cm layer of soils is noted directly in affected zone on the plots situated at 1.2, 1.6, 5.0, 8.0 km from emission source in the direction of prevailing winds. The maximum quantity of a pollutant was founded in the soil of the plot located mostly close to a source of pollution in the direction of prevailing winds

  3. Analysis of Subcritical Crack Growth in Dental Ceramics Using Fracture Mechanics and Fractography

    Science.gov (United States)

    Taskonak, Burak; Griggs, Jason A.; Mecholsky, John J.; Yan, Jia-Hau

    2008-01-01

    Objectives The aim of this study was to test the hypothesis that the flexural strengths and critical flaw sizes of dental ceramic specimens will be affected by the testing environment and stressing rate even though their fracture toughness values will remain the same. Methods Ceramic specimens were prepared from an aluminous porcelain (Vitadur Alpha; VITA Zahnfabrik, Bad Säckingen, Germany) and an alumina-zirconia-glass composite (In-Ceram® Zirconia; VITA Zahnfabrik). Three hundred uniaxial flexure specimens (150 of each material) were fabricated to dimensions of 25 mm × 4 mm × 1.2 mm according to the ISO 6872 standard. Each group of 30 specimens was fractured in water using one of four different target stressing rates ranging on a logarithmic scale from 0.1 to 100 MPa/s for Vitadur Alpha and from 0.01 to 10 MPa/s for In-Ceram® Zirconia. The fifth group was tested in inert environment (oil) with a target stressing rate of 100 MPa/s for Vitadur Alpha and 1000 MPa/s for In-Ceram® Zirconia. The effects of stressing rate and environment on flexural strength, critical flaw size, and fracture toughness were analyzed statistically by Kruskal-Wallis one-way ANOVA on ranks followed by post-hoc comparisons using Dunn’s test (α=0.05). In addition, 20 Vitadur Alpha specimens were fabricated with controlled flaws to simplify fractography. Half of these specimens were fracture tested in water and half in oil at a target stressing rate of 100 MPa/s, and the results were compared using Mann-Whitney rank sum tests (α=0.05). A logarithmic regression model was used to determine the fatigue parameters for each material. Results For each ceramic composition, specimens tested in oil had significantly higher strength (P≤0.05) and smaller critical flaw size (significant for Vitadur Alpha, P≤0.05) than those tested in water but did not have significantly different fracture toughness (P>0.05). Specimens tested at faster stressing rates had significantly higher strength (P≤0

  4. Spatially confined assembly of nanoparticles.

    Science.gov (United States)

    Jiang, Lin; Chen, Xiaodong; Lu, Nan; Chi, Lifeng

    2014-10-21

    The ability to assemble NPs into ordered structures that are expected to yield collective physical or chemical properties has afforded new and exciting opportunities in the field of nanotechnology. Among the various configurations of nanoparticle assemblies, two-dimensional (2D) NP patterns and one-dimensional (1D) NP arrays on surfaces are regarded as the ideal assembly configurations for many technological devices, for example, solar cells, magnetic memory, switching devices, and sensing devices, due to their unique transport phenomena and the cooperative properties of NPs in assemblies. To realize the potential applications of NP assemblies, especially in nanodevice-related applications, certain key issues must still be resolved, for example, ordering and alignment, manipulating and positioning in nanodevices, and multicomponent or hierarchical structures of NP assemblies for device integration. Additionally, the assembly of NPs with high precision and high levels of integration and uniformity for devices with scaled-down dimensions has become a key and challenging issue. Two-dimensional NP patterns and 1D NP arrays are obtained using traditional lithography techniques (top-down strategies) or interfacial assembly techniques (bottom-up strategies). However, a formidable challenge that persists is the controllable assembly of NPs in desired locations over large areas with high precision and high levels of integration. The difficulty of this assembly is due to the low efficiency of small features over large areas in lithography techniques or the inevitable structural defects that occur during the assembly process. The combination of self-assembly strategies with existing nanofabrication techniques could potentially provide effective and distinctive solutions for fabricating NPs with precise position control and high resolution. Furthermore, the synergistic combination of spatially mediated interactions between nanoparticles and prestructures on surfaces may play

  5. Construction of a standard test assembly for controlled laser studies in tissues: preliminary study on human bone material.

    Science.gov (United States)

    Beer, Franziska; Passow, Harald

    2008-02-01

    The aim of the study is the construction of a test assembly, which facilitates objective, comparative studies on the cutting performance of lasers in hard tissue. To ensure the applicability of our own construction for the reproducible performance of laser incisions in hard tissue, eleven freshly extracted blocks (2x1.5 cm2) of human bone were prepared with a Er,Cr:YSGG laser by using a handheld handpiece, respectively, using the constructed device for a standardized cutting. A total of 44 cuts were executed. The specimen were then histologically evaluated. The standard test assembly met the requirements concerning the provision of objective results. The findings of the histological evaluation prove the reproducibility of the results. The standard test assembly presented in this paper facilitates comparative studies of different laser systems by reducing subjective influence on the preparation to a minimum. The results of this preliminary study show that the precision of the guiding instrument for laser cutting reduces the error of cut width by 50-fold, from 50 to 1 microm.

  6. The impact of resin-coating on sub-critical crack extension in a porcelain laminate veneer material.

    Science.gov (United States)

    Cao, Xu; Fleming, Garry J P; Addison, Owen

    2017-05-01

    Characterisation of the interaction between crack extension, crack stabilisation and stress/strain relaxation in the polymeric matrix, the interplay between stress corrosion cracking and the mechanical response of a resin-based luting adhesive within a surface defect population could extend PLV restoration longevity by optimising cementation protocols. The aim was to investigate the influence of stress corrosion cracking and the viscoelastic behaviour of a resin-based luting adhesive independently by controlling the environmental conditions operative during test specimen fabrication. The effects of stress corrosion at ceramic crack tips and potential viscoelastic responses to loading of the resin-coated impregnating cracks were isolated. Resin-coated feldspathic ceramic test specimens were fabricated in ambient humidity or following moisture exclusion. Bi-axial flexure strengths of groups (n = 20) were determined at constant loading rates of 2.5, 10, 40, 160 or 640 N/min and data was compared with uncoated controls. Fractographic analyses were performed on all fractured test specimens. Resin-cement coating resulted in significant ceramic strengthening in all conditions tested (p < 0.01). A two-way ANOVA demonstrated that the exclusion of moisture during resin- coating significantly increased mean BFS (p<0.01) but post-hoc Tukey tests identified that moisture exclusion resulted in significant increases in BFS values only at intermediate loading rates with no significant differences observed at either the fastest or slowest loading rates (640 and 2.5 N/min, respectively). Mechanical reinforcement of PLV materials by resin-cement systems is yet to be optimized. The viscoelastic behavior of the resin-cement itself can influence the magnitude of reinforcement observed and sub-critical crack growth. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Sub-15 nm nano-pattern generation by spacer width control for high density precisely positioned self-assembled device nanomanufacturing

    KAUST Repository

    Rojas, Jhonathan Prieto

    2012-08-01

    We present a conventional micro-fabrication based thin film vertical sidewall (spacer) width controlled nano-gap fabrication process to create arrays of nanopatterns for high density precisely positioned self-assembled nanoelectronics device integration. We have used conventional optical lithography to create base structures and then silicon nitride (Si 3N4) based spacer formation via reactive ion etching. Control of Si3N4 thickness provides accurate control of vertical sidewall (spacer) besides the base structures. Nano-gaps are fabricated between two adjacent spacers whereas the width of the gap depends on the gap between two adjacent base structures minus width of adjacent spacers. We demonstrate the process using a 32 nm node complementary metal oxide semiconductor (CMOS) platform to show its compatibility for very large scale heterogeneous integration of top-down and bottom-up fabrication as well as conventional and selfassembled nanodevices. This process opens up clear opportunity to overcome the decade long challenge of high density integration of self-assembled devices with precise position control. © 2012 IEEE.

  8. Analysis of product distribution and characteristics in hydrothermal liquefaction of barley straw in subcritical and supercritical water

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this study, hydrothermal liquefaction of barley straw in subcritical and supercritical water with potassium carbonate catalyst was performed in the temperatures range of 280-400°C. The influence of final reaction temperature on products yield was investigated and some physicochemical properties...

  9. Supercritical CO(2) and subcritical propane extraction of pungent paprika and quantification of carotenoids, tocopherols, and capsaicinoids.

    Science.gov (United States)

    Gnayfeed, M H; Daood, H G; Illés, V; Biacs, P A

    2001-06-01

    Ground paprika (Capsicum annuum L.) was extracted with supercritical carbon dioxide (SC-CO(2)) and subcritical propane at different conditions of pressure and temperature to estimate the yield and variation in carotenoid, tocopherol, and capsaicinoid contents and composition. The yield of paprika extract was found to be affected by the extraction conditions with SC-CO(2) but fairly constant at different conditions with subcritical propane. The maximum yields of oleoresin were 7.9 and 8.1% of ground paprika by SC-CO(2) and subcritical propane, respectively. The quantitative distribution of carotenoids, tocopherols, and capsaicinoids between paprika extract and powder was influenced by extraction conditions. SC-CO(2) was inefficient in the extraction of diesters of xanthophylls even at 400 bar and 55 degrees C, whereas tocopherols and capsaicinoids were easy to extract at these conditions. Under mild conditions subcritical propane was superior to SC-CO(2) in the extraction of carotenoids and tocopherols but less efficient in the extraction of capsaicinoids.

  10. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    Science.gov (United States)

    Pan, Z.; Chou, I.-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water. ?? 2009 The Royal Society of Chemistry.

  11. Optical control of electron spin dynamics in self-assembled (In,Ga)As/GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Greilich, A.; Oulton, R.; Zhukov, E.A.; Yugova, I.A.; Yakovlev, D.R.; Bayer, M. [Experimentelle Physik II, Universitaet Dortmund, 44221 Dortmund (Germany); Shabaev, A.; Efros, Al.L. [Naval Research Laboratory, Washington, DC 20375 (United States); Stavarache, V.; Reuter, D.; Wieck, A. [Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2006-11-15

    Spin coherence has been studied in self-assembled (In,Ga)As/GaAs quantum dots which contain on average a single electron per dot due to n-type modulation doping. A magnetic field was applied in the Voigt geometry, in order to study the precession of the electron spins which are oriented normal to the field. Here we address the mechanism by which such a normal orientation can be achieved by resonant excitation with circularly polarized laser pulses. Further, we discuss, how long this coherence is maintained within an ensemble of quantum dots. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Binary Mixtures of SH- and CH3-Terminated Self-Assembled Monolayers to Control the Average Spacing Between Aligned Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Pavelka Laura

    2009-01-01

    Full Text Available Abstract This paper presents a method to control the average spacing between organometallic chemical vapor deposition (OMCVD grown gold nanoparticles (Au NPs in a line. Focused ion beam patterned CH3-terminated self-assembled monolayers are refilled systematically with different mixtures of SH- and CH3-terminated silanes. The average spacing between OMCVD Au NPs is demonstrated systematically to decrease by increasing the v/v% ratio of the thiols in the binary silane mixtures with SH- and CH3-terminated groups.

  13. Composite state control and magnetic properties of Co and Si cluster assemblies prepared with double-glow-discharge sources

    Science.gov (United States)

    Katoh, Ryoji; Hihara, Takehiko; Peng, Dong-Liang; Sumiyama, Kenji

    2006-08-01

    Using a double-glow-discharge-cluster-source system, in which one glow discharge was a dc mode and the other an rf discharge mode, Co and Si clusters were independently produced and simultaneously deposited on a substrate. When a separation plate was inserted between two glow-discharge chambers, a mixture of Co and Si clusters was obtained: small Co clusters were distributed at random, while the Si clusters were aggregated to form large secondary particles. Without inserting the separation plate, on the other hand, core-shell clusters were obtained: a Co core was surrounded by small Si crystallites. The magnetization measurement indicated that the magnetic coercive force of Co /Si core-shell cluster assemblies was much smaller than that of Co cluster assemblies in which Co clusters were covered with antiferromagnetic CoO shells, indicating that the Si shell prevented Co cluster surfaces from their oxidation. Therefore, the present double-cluster-source system is useful in fabricating various sorts of cluster composites, which cannot be prepared by conventional coevaporation or precipitation methods.

  14. Transmembrane Complexes of DAP12 Crystallized in Lipid Membranes Provide Insights into Control of Oligomerization in Immunoreceptor Assembly

    Directory of Open Access Journals (Sweden)

    Konstantin Knoblich

    2015-05-01

    Full Text Available The membrane-spanning α helices of single-pass receptors play crucial roles in stabilizing oligomeric structures and transducing biochemical signals across the membrane. Probing intermolecular transmembrane interactions in single-pass receptors presents unique challenges, reflected in a gross underrepresentation of their membrane-embedded domains in structural databases. Here, we present two high-resolution structures of transmembrane assemblies from a eukaryotic single-pass protein crystallized in a lipidic membrane environment. Trimeric and tetrameric structures of the immunoreceptor signaling module DAP12, determined to 1.77-Å and 2.14-Å resolution, respectively, are organized by the same polar surfaces that govern intramembrane assembly with client receptors. We demonstrate that, in addition to the well-studied dimeric form, these trimeric and tetrameric structures are made in cells, and their formation is competitive with receptor association in the ER. The polar transmembrane sequences therefore act as primary determinants of oligomerization specificity through interplay between charge shielding and sequestration of polar surfaces within helix interfaces.

  15. The Effect of Subcritical Bone Loss and Exposure on Recurrent Instability After Arthroscopic Bankart Repair in Intercollegiate American Football.

    Science.gov (United States)

    Dickens, Jonathan F; Owens, Brett D; Cameron, Kenneth L; DeBerardino, Thomas M; Masini, Brendan D; Peck, Karen Y; Svoboda, Steven J

    2017-07-01

    There is no consensus on the optimal method of stabilization (arthroscopic or open) in collision athletes with anterior shoulder instability. To examine the effect of "subcritical" bone loss and football-specific exposure on the rate of recurrent shoulder instability after arthroscopic stabilization in an intercollegiate American football population. Case-control study; Level of evidence, 3. Fifty intercollegiate football players underwent primary arthroscopic stabilization for anterior shoulder instability and returned to football for at least a single season. Preoperatively, 32 patients experienced recurrent subluxations, and 18 patients experienced a single or recurrent dislocation. Shoulders with glenoid bone loss >20%, an engaging Hill-Sachs lesion, an off-track lesion, and concomitant rotator cuff repair were excluded from the study. The primary outcome of interest was the ability to return to football without subsequent instability. Patients were followed for time to a subsequent instability event after return to play using days of exposure to football and total follow-up time after arthroscopic stabilization. Fifty consecutive patients returned to American football for a mean 1.5 seasons (range, 1-3) after arthroscopic stabilization. Three of 50 (6%; 95% CI, 1.3%-16.5%) patients experienced recurrent instability. There were no subsequent instability events after a mean 3.2 years of military service. All shoulders with glenoid bone loss >13.5% (n = 3) that underwent arthroscopic stabilization experienced recurrent instability upon returning to sport, while none of the shoulders with football ( X 2 = 15.80, P 13.5% glenoid bone loss had an incidence rate of 5.31 cases of recurrent instability per 1000 athlete-exposures of football. In 72,000 athlete-exposures to football with football players with <13.5% glenoid bone loss provides reliable outcomes and low recurrence rates.

  16. Controlled deposition of functionalized silica coated zinc oxide nano-assemblies at the air/water interface for blood cancer detection

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandra Mouli [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Nanobioelectronics Laboratory, Department of Biotechnology, Delhi Technological University, Delhi 110042 (India); Dewan, Srishti [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Biomedical Engineering Department, Deenbandhu Chhotu Ram University of Science & Technology, Haryana 131039 (India); Chawla, Seema [Biomedical Engineering Department, Deenbandhu Chhotu Ram University of Science & Technology, Haryana 131039 (India); Yadav, Birendra Kumar [Rajiv Gandhi Cancer Institute and Research Centre, Rohini, Delhi 110085 (India); Sumana, Gajjala, E-mail: sumanagajjala@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Malhotra, Bansi Dhar, E-mail: bansi.malhotra@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Nanobioelectronics Laboratory, Department of Biotechnology, Delhi Technological University, Delhi 110042 (India)

    2016-09-21

    We report results of the studies relating to controlled deposition of the amino-functionalized silica-coated zinc oxide (Am-Si@ZnO) nano-assemblies onto an indium tin oxide (ITO) coated glass substrate using Langmuir-Blodgett (LB) technique. The monolayers have been deposited by transferring the spread solution of Am-Si@ZnO stearic acid prepared in chloroform at the air-water interface, at optimized pressure (16 mN/m), concentration (10 mg/ml) and temperature (23 °C). The high-resolution transmission electron microscopic studies of the Am-Si@ZnO nanocomposite reveal that the nanoparticles have a microscopic structure comprising of hexagonal assemblies of ZnO with typical dimensions of 30 nm. The surface morphology of the LB multilayer observed by scanning electron microscopy shows uniform surface of the Am-Si@ZnO film in the nanometer range (<80 nm). These electrodes have been utilized for chronic myelogenous leukemia (CML) detection by covalently immobilizing the amino-terminated oligonucleotide probe sequence via glutaraldehyde as a crosslinker. The response studies of these fabricated electrodes carried out using electrochemical impedance spectroscopy show that this Am-Si@ZnO LB film based nucleic acid sensor exhibits a linear response to complementary DNA (10{sup −6}–10{sup −16} M) with a detection limit of 1 × 10{sup −16} M. This fabricated platform is validated with clinical samples of CML positive patients and the results demonstrate its immense potential for clinical diagnosis. - Graphical abstract: Controlled deposition of functionalized silica coated zinc oxide nano-assemblies at the air/water interface for label free electrochemical detection of chronic myelogenous leukemia. - Highlights: • Stable and controlled deposition of Am-Si@ZnO nano-assemblies using LB technique. • Uniform monolayer deposition of the Am-Si@ZnO LB film within the nanometer range. • Am-Si@ZnO LB film shows enhanced electrochemical properties. • Fabricated

  17. Hierarchical self-assembly of magnetic nanoclusters for theranostics: Tunable size, enhanced magnetic resonance imagability, and controlled and targeted drug delivery.

    Science.gov (United States)

    Nguyen, Dai Hai; Lee, Jung Seok; Choi, Jong Hoon; Park, Kyung Min; Lee, Yunki; Park, Ki Dong

    2016-04-15

    Nanoparticle-based imaging and therapy are of interest for theranostic nanomedicine. In particular, superparamagnetic iron oxide (SPIO) nanoparticles (NPs) have attracted much attention in cancer imaging, diagnostics, and treatment because of their superior imagability and biocompatibility (approved by the Food and Drug Administration). Here, we developed SPIO nanoparticles (NPs) that self-assembled into magnetic nanoclusters (SAMNs) in aqueous environments as a theranostic nano-system. To generate multi-functional SPIO NPs, we covalently conjugated β-cyclodextrin (β-CD) to SPIO NPs using metal-adhesive dopamine groups. Polyethylene glycol (PEG) and paclitaxel (PTX) were hosted in the β-CD cavity through high affinity complexation. The core-shell structure of the magnetic nanoclusters was elucidated based on the condensed SPIO core and a PEG shell using electron microscopy and the composition was analyzed by thermogravimetric analysis (TGA). Our results indicate that nanocluster size could be readily controlled by changing the SPIO/PEG ratio in the assemblies. Interestingly, we observed a significant enhancement in magnetic resonance contrast due to the large cluster size and dense iron oxide core. In addition, tethering a tumor-targeting peptide to the SAMNs enhanced their uptake into tumor cells. PTX was efficiently loaded into β-CDs and released in a controlled manner when exposed to competitive guest molecules. These results strongly indicate that the SAMNs developed in this study possess great potential for application in image-guided cancer chemotherapy. In this study, we developed multi-functional SPIO NPs that self-assembled into magnetic nanoclusters (SAMNs) in aqueous conditions as a theranostic nano-system. The beta-cyclodextrin (β-CD) was immobilized on the surfaces of SPIO NPs and RGD-conjugated polyethylene glycol (PEG) and paclitaxel (PTX) were hosted in the β-CD cavity through high affinity complexation. We found that nanocluster size could be

  18. FINAL DESIGN REVIEW REPORT Subcritical Experiments Gen 2, 3-ft Confinement Vessel Weldment

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    A Final Design Review (FDR) of the Subcritical Experiments (SCE) Gen 2, 3-ft. Confinement Vessel Weldment was held at Los Alamos National Laboratory (LANL) on September 14, 2017. The review was a focused review on changes only to the confinement vessel weldment (versus a system design review). The changes resulted from lessons-learned in fabricating and inspecting the current set of confinement vessels used for the SCE Program. The baseline 3-ft. confinement vessel weldment design has successfully been used (to date) for three (3) high explosive (HE) over-tests, two (2) fragment tests, and five (5) integral HE experiments. The design team applied lessons learned from fabrication and inspection of these vessel weldments to enhance fit-up, weldability, inspection, and fitness for service evaluations. The review team consisted of five (5) independent subject matter experts with engineering design, analysis, testing, fabrication, and inspection experience. The

  19. Conceptual study of high power proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Ouyang Hua Fu; Xu Tao Guang

    2001-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. The ADS accelerator presented by the consists of a 5 MeV radio-frequency quadrupole, a 100 MeV independently phased superconducting cavity linac and a 1 GeV elliptical superconducting cavity linac. The accelerating structures and main parameters are determined and the research and development plan is considered

  20. Conceptual design based on scale laws and algorithms for sub-critical transmutation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Gu; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    In order to conduct the effective integration of computer-aided conceptual design for integrated nuclear power reactor, not only is a smooth information flow required, but also decision making for both conceptual design and construction process design must be synthesized. In addition to the aboves, the relations between the one step and another step and the methodologies to optimize the decision variables are verified, in this paper especially, that is, scaling laws and scaling criteria. In the respect with the running of the system, the integrated optimization process is proposed in which decisions concerning both conceptual design are simultaneously made. According to the proposed reactor types and power levels, an integrated optimization problems are formulated. This optimization is expressed as a multi-objective optimization problem. The algorithm for solving the problem is also presented. The proposed method is applied to designing a integrated sub-critical reactors. 6 refs., 5 figs., 1 tab. (Author)

  1. Kinetic model for the esterification of oleic acid catalyzed by zinc acetate in subcritical methanol

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chengcai; Deng, Tiansheng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Qi, Yongqin; Hou, Xianglin; Qin, Zhangfeng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China)

    2010-03-15

    The esterification of oleic acid in subcritical methanol catalyzed by zinc acetate was investigated in a batch-type autoclave. The effect of reaction conditions such as temperature, pressure, reaction time and molar ratio of oleic acid to methanol on the esterification was examined. The oleic acid conversion reached 95.0% under 220 C and 6.0 MPa with the molar ratio of methanol to oleic acid being 4 and 1.0 wt% zinc acetate as catalyst. A kinetic model for the esterification was established. By fitting the kinetic model with the experimental results, the reaction order n = 2.2 and activation energy E{sub a} = 32.62 KJ/mol were obtained. (author)

  2. The mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water

    Science.gov (United States)

    Yu, Zhuanni; Chen, Xiaolin; Xia, Shuwei

    2016-06-01

    In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.

  3. An integrated green process: Subcritical water, enzymatic hydrolysis, and fermentation, for biohydrogen production from coconut husk.

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Ranggina, Dian; Nurtono, Tantular; Widjaja, Arief

    2017-10-09

    The objective of this work is to develop an integrated green process of subcritical water (SCW), enzymatic hydrolysis and fermentation of coconut husk (CCH) to biohydrogen. The maximum sugar yield was obtained at mild severity factor. This was confirmed by the degradation of hemicellulose, cellulose and lignin. The tendency of the changing of sugar yield as a result of increasing severity factor was opposite to the tendency of pH change. It was found that CO2 gave a different tendency of severity factor compared to N2 as the pressurizing gas. The result of SEM analysis confirmed the structural changes during SCW pretreatment. This study integrated three steps all of which are green processes which ensured an environmentally friendly process to produce a clean biohydrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, D. B., E-mail: dschaeffer@physics.ucla.edu; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Gekelman, W.; Niemann, C. [Department of Physics and Astronomy, University of California—Los Angeles, Los Angeles, California 90095 (United States); Winske, D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2015-11-15

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  5. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, Adnane; Turner, Drew L.; Wilson, Lynn B.; Dimmock, Andrew P.; Pulkkinen, Tuija I.

    2017-09-01

    The discovery of long-lived electrostatic coherent structures with large-amplitude electric fields (1≤slant E ≤slant 500 mV/m) by the Van Allen Probes has revealed alternative routes through which planetary radiation belts’ acceleration can take place. Following previous reports showing that small phase-space holes, with qφ /{T}ec≃ {10}-2{--}{10}-3, could result from electron interaction with large-amplitude whistlers, we demonstrate one possible mechanism through which holes can grow nonlinearly (I.e., γ \\propto \\sqrt{φ }) and subcritically as a result of momentum exchange between hot and cold electron populations. Our results provide an explanation for the common occurrence and fast growth of large-amplitude electron phase-space holes in the Earth’s radiation belts.

  6. A review on green trend for oil extraction using subcritical water technology and biodiesel production.

    Science.gov (United States)

    Abdelmoez, Weal; Ashour, Eman; Naguib, Shahenaz M

    2015-01-01

    It became a global agenda to develop clean alternative fuels which were domestically available, environmentally acceptable and technically feasible. Thus, biodiesel was destined to make a substantial contribution to the future energy demands of the domestic and industrial economies. Utilization of the non edible vegetable oils as raw materials for biodiesel production had been handled frequently for the past few years. The oil content of these seeds could be extracted by different oil extraction methods, such as mechanical extraction, solvent extraction and by subcritical water extraction technology SWT. Among them, SWT represents a new promising green extraction method. Therefore this review covered the current used non edible oil seeds for biodiesel production as well as giving a sharp focus on the efficiency of using the SWT as a promising extraction method. In addition the advantages and the disadvantages of the different biodiesel production techniques would be covered.

  7. Nonlinear elastic behavior of sub-critically damaged body armor panel

    Science.gov (United States)

    Fisher, Jason T.; Chimenti, D. E.

    2012-05-01

    A simple go/no-go test for body armor panels using pressure-sensitive, dye-indicator film (PSF) has been shown to be statistically effective in revealing subcritical damage to body armor panels. Previous measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Further impact tests on armor worn by a human resuscitation dummy using instrumented masses with an attached accelerometer and embedded force transducer have been performed and analyzed. New impact tests have shown a reliable correlation between PSF indication (as digitized images) and impact force for a wide range of impactor energies and masses. Numerical evaluation of digital PSF images is presented and correlated with impact parameters. Relationships between impactor mass and energy, and corresponding measured force are shown. We will also report on comparisons between ballistic testing performed on panels damaged under various impact conditions and tests performed on undamaged panels.

  8. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    Science.gov (United States)

    Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio

    2014-04-01

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.

  9. Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

    Science.gov (United States)

    O'Kelly, David Sean

    Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

  10. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Science.gov (United States)

    Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Winske, D.; Gekelman, W.; Niemann, C.

    2015-11-01

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  11. Source-jerk method for application on ADS neutronics study The ADS is stated for Accelerator Driven sub-critical System

    CERN Document Server

    Zhu Qing Fu; Li Yi; Xia Pu; Zheng Wu Qing; Zhu Guo Sheng

    2003-01-01

    The paper is concerned in the source-jerk method used to measure the sub-criticality, and the sub-critical experiment facility, which is used for the study on the neutronics of ADS, driven by external neutron source sup 2 sup 5 sup 2 Cf. The effects of the location of neutron source and material buffer where is at the location of the pipe of proton beam and target of fission-product dispersion on the sub-criticality of reactor are studied by source-jerk method

  12. Global bifurcations to subcritical magnetorotational dynamo action in Keplerian shear flow

    Science.gov (United States)

    Riols, A.; Rincon, F.; Cossu, C.; Lesur, G.; Longaretti, P.-Y.; Ogilvie, G. I.; Herault, J.

    2013-09-01

    Magnetorotational dynamo action in Keplerian shear flow is a three-dimensional, nonlinear magnetohydrodynamic process whose study is relevant to the understanding of accretion and magnetic field generation in astrophysics. Transition to this form of dynamo is subcritical and shares many characteristics of transition to turbulence in non-rotating hydrodynamic shear flows. This suggests that these different fluid systems become active through similar generic bifurcation mechanisms, which in both cases have eluded detailed understanding so far. In this paper, we investigate numerically the bifurcation mechanisms at work in the incompressible Keplerian magnetorotational dynamo problem in the shearing box framework. Using numerical techniques imported from dynamical systems research, we show that the onset of chaotic dynamo action at magnetic Prandtl numbers larger than unity is primarily associated with global homoclinic and heteroclinic bifurcations of nonlinear magnetorotational dynamo cycles. These global bifurcations are supplemented by local bifurcations of cycles marking the beginning of period-doubling cascades. This suggests that nonlinear magnetorotational dynamo cycles provide the pathway to turbulent injection of both kinetic and magnetic energy in incompressible magnetohydrodynamic Keplerian shear flow in the absence of an externally imposed magnetic field. Studying the nonlinear physics and bifurcations of these cycles in different regimes and configurations may subsequently help to better understand the conditions of excitation of magnetohydrodynamic turbulence and instability-driven dynamos in various astrophysical systems and laboratory experiments. The detailed characterization of global bifurcations provided for this three-dimensional subcritical fluid dynamics problem may also prove useful for the problem of transition to turbulence in hydrodynamic shear flows.

  13. Application of supercritical and subcritical fluids for the extraction of hazardous materials from soil

    Directory of Open Access Journals (Sweden)

    Skorupan Dara

    2002-01-01

    Full Text Available Subcritical and supercritical extractions are novel, non destructive techniques which can be applied for the removal of hazardous compounds from contaminated soil without any changes of the soil composition and structure. The aim of the presented review paper is to give information on up-to day results of this method commonly applied by several institutions worldwide. Interest in the application of SC CO2 has been more expressed in the last two decades, which may be related to its favorable characteristics (non-toxic, non-flammable, increase diffusion into small pores, low viscosity under SC conditions, low price and others. However, interest in wet oxidation (WO and especially in SCWO (the application of water under supercritical conditions with air has also increased in the last few years. Interest in H2O as a SC fluid, as well as in extraction with water under subcritical conditions may also be related to specific characteristics and the enhanced rate of extraction. Moreover, the solubility of some specific compounds present in soil can be easily changed by adjusting the pressure and temperature of extraction. The high price of the units designed to operate safely at a pressure and temperature much higher than the a critical one of the applied fluids is the main reason why, at present, there is no more broader application of such techniques for the removal hazardous materials from contaminated soil. In the present paper, among many literature citations and their overall review, some specific details related to the development of specific analytical methods under SC conditions are also considered.

  14. TNT and RDX degradation and extraction from contaminated soil using subcritical water.

    Science.gov (United States)

    Islam, Mohammad Nazrul; Shin, Moon-Su; Jo, Young-Tae; Park, Jeong-Hun

    2015-01-01

    The use of explosives either for industrial or military operations have resulted in the environmental pollution, poses ecological and health hazard. In this work, a subcritical water extraction (SCWE) process at laboratory scale was used at varying water temperature (100-175 °C) and flow rate (0.5-1.5 mL min(-1)), to treat 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soil, to reveal information with respect to the explosives removal (based on the analyses of soil residue after extraction), and degradation performance (based on the analyses of water extracts) of this process. Continuous flow subcritical water has been considered on removal of explosives to avoid the repartitioning of non-degraded compounds to the soil upon cooling which usually occurs in the batch system. In the SCWE experiments, near complete degradation of both TNT and RDX was observed at 175 °C based on analysis of water extracts and soil. Test results also indicated that TNT removal of >99% and a complete RDX removal were achieved by this process, when the operating conditions were 1 mL min(-1), and treatment time of 20 min, after the temperature reached 175 °C. HPLC-UV and ion chromatography analysis confirmed that the explosives underwent for degradation. The low concentration of explosives found in the process wastewater indicates that water recycling may be viable, to treat additional soil. Our results have shown in the remediation of explosives contaminated soil, the effectiveness of the continuous flow SCWE process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Highly Selective and Considerable Subcritical Butane Extraction to Separate Abamectin in Green Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Pang, Huili; Qin, Guangyong

    2017-06-01

    We specially carried out the subcritical butane extraction to separate abamectin from tea leaves. Four parameters, such as extraction temperature, extraction time, number of extraction cycles, and solid-liquid ratio were studied and optimized through the response surface methodology with design matrix developed by Box-Behnken. Seventeen experiments with three various factors and three variable levels were employed to investigate the effect of these parameters on the extraction of abamectin. Besides, catechins, theanine, caffeine, and aroma components were determined by both high-performance liquid chromatography and gas chromatography-mass spectrometry to evaluate the tea quality before and after the extraction. The results showed that the extraction temperature was the uppermost parameter compared with others. The optimal extraction conditions selected as follows: extraction temperature, 42°C; number of extraction cycles and extraction time, 1 and 30 min, respectively; and solid-liquid ratio, 1:10. Based on the above study, the separation efficiency of abamectin was up to 93.95%. It is notable that there has a quite low loss rate, including the negligible damage of aroma components, the bits reduce of catechins within the range of 0.7%-13.1%, and a handful lessen of caffeine and theanine of 1.81% and 2.6%, respectively. The proposed method suggested subcritical butane possesses solubility for lipid-soluble pesticides, and since most of the pesticides are attached to the surfaces of tea, thus the as-applied method was successfully effective to separate abamectin because of the so practical and promising method.

  16. General Assembly

    CERN Multimedia

    Staff Association

    2016-01-01

    5th April, 2016 – Ordinary General Assembly of the Staff Association! In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Tuesday, April 5th 2016 from 11:00 to 12:00 in BE Auditorium, Meyrin (6-2-024). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its financial management, and an opportunity to express one’s opinion, including taking part in the votes. Other points are listed on the agenda, as proposed by the Staff Council. Who can vote? Only “ordinary” members (MPE) of the SA can vote. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give his/her opinion? The Ordinary General Asse...

  17. Photovoltaic self-assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Lavin, Judith; Kemp, Richard Alan; Stewart, Constantine A.

    2010-10-01

    This late-start LDRD was focused on the application of chemical principles of self-assembly on the ordering and placement of photovoltaic cells in a module. The drive for this chemical-based self-assembly stems from the escalating prices in the 'pick-and-place' technology currently used in the MEMS industries as the size of chips decreases. The chemical self-assembly principles are well-known on a molecular scale in other material science systems but to date had not been applied to the assembly of cells in a photovoltaic array or module. We explored several types of chemical-based self-assembly techniques, including gold-thiol interactions, liquid polymer binding, and hydrophobic-hydrophilic interactions designed to array both Si and GaAs PV chips onto a substrate. Additional research was focused on the modification of PV cells in an effort to gain control over the facial directionality of the cells in a solvent-based environment. Despite being a small footprint research project worked on for only a short time, the technical results and scientific accomplishments were significant and could prove to be enabling technology in the disruptive advancement of the microelectronic photovoltaics industry.

  18. Initial condition of stochastic self-assembly.

    Science.gov (United States)

    Davis, Jason K; Sindi, Suzanne S

    2016-02-01

    The formation of a stable protein aggregate is regarded as the rate limiting step in the establishment of prion diseases. In these systems, once aggregates reach a critical size the growth process accelerates and thus the waiting time until the appearance of the first critically sized aggregate is a key determinant of disease onset. In addition to prion diseases, aggregation and nucleation is a central step of many physical, chemical, and biological process. Previous studies have examined the first-arrival time at a critical nucleus size during homogeneous self-assembly under the assumption that at time t=0 the system was in the all-monomer state. However, in order to compare to in vivo biological experiments where protein constituents inherited by a newly born cell likely contain intermediate aggregates, other possibilities must be considered. We consider one such possibility by conditioning the unique ergodic size distribution on subcritical aggregate sizes; this least-informed distribution is then used as an initial condition. We make the claim that this initial condition carries fewer assumptions than an all-monomer one and verify that it can yield significantly different averaged waiting times relative to the all-monomer condition under various models of assembly.

  19. Controlled self-assembling structures of ferrocene-dipeptide conjugates composed of Ala-Pro-NHCH2CH2SH chain.

    Science.gov (United States)

    Moriuchi, Toshiyuki; Nishiyama, Taiki; Tayano, Yoshiki; Hirao, Toshikazu

    2017-05-18

    Bioorganometallic ferrocene-dipeptide conjugates with the Ala-Pro-cysteamine chain, Fc-L-Ala-L-Pro-NHCH2CH2SH (2) and Fc-L-Ala-D-Pro-NHCH2CH2SH (4) (Fc=ferrocenoyl), were prepared by the reduction of the ferrocene-dipeptide conjugates, Fc-L-Ala-L-Pro-cystamine-L-Pro-L-Ala-Fc (1) or Fc-L-Ala-D-Pro-cystamine-D-Pro-L-Ala-Fc (3), respectively. Control of the self-assembling structures of the ferrocene-dipeptide conjugates was demonstrated by changing the chirality of the amino acid. The molecular structure of 2 composed of the L-Ala-L-Pro-NHCH2CH2SH chain confirmed the formation of intramolecular hydrogen bond of N-H⋯N pattern between the NH of cysteamine moiety and the nitrogen of Pro moiety. Furthermore, intermolecular hydrogen bonds between NH (Ala) and CO (Pro of another molecule) and between NH (cysteamine) and CO (the ferrocenoyl moiety of another molecule) were formed, wherein each molecule is connected to four neighboring molecules by continuous intermolecular hydrogen bonds to form the hydrogen-bonded molecular assembling structure. On the contrary, the left-handed helical assembly through an intermolecular hydrogen-bonding network of 15-membered intermolecularly hydrogen-bonded ring between NH (Ala) and CO (the ferrocenoyl moiety of another molecule) and between NH (the cysteamine moiety of another molecule) and CO (Ala) was observed in the crystal packing of 4 composed of the L-Ala-D-Pro-NHCH2CH2SH chain. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. SIMPLE METHOD FOR ESTIMATING POLYCHLORINATED BIPHENYL CONCENTRATIONS ON SOILS AND SEDIMENTS USING SUBCRITICAL WATER EXTRACTION COUPLED WITH SOLID-PHASE MICROEXTRACTION. (R825368)

    Science.gov (United States)

    A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a seale...

  1. Short communication: antiviral activity of subcritical water extract of Brassica juncea against influenza virus A/H1N1 in nonfat milk

    National Research Council Canada - National Science Library

    Lee, N-K; Lee, J-H; Lim, S-M; Lee, K A; Kim, Y B; Chang, P-S; Paik, H-D

    2014-01-01

    Subcritical water extract (SWE) of Brassica juncea was studied for antiviral effects against influenza virus A/H1N1 and for the possibility of application as a nonfat milk supplement for use as an "antiviral food...

  2. Assembling consumption

    DEFF Research Database (Denmark)

    Assembling Consumption marks a definitive step in the institutionalisation of qualitative business research. By gathering leading scholars and educators who study markets, marketing and consumption through the lenses of philosophy, sociology and anthropology, this book clarifies and applies...... the investigative tools offered by assemblage theory, actor-network theory and non-representational theory. Clear theoretical explanation and methodological innovation, alongside empirical applications of these emerging frameworks will offer readers new and refreshing perspectives on consumer culture and market...... societies. This is an essential reading for both seasoned scholars and advanced students of markets, economies and social forms of consumption....

  3. pH-value-controlled assembly of photoluminescent zinc coordination polymers in the mixed-ligand system

    Science.gov (United States)

    Liu, Kang; Hu, Hanbin; Sun, Jing; Zhang, Yiheng; Han, Jishu; Wang, Lei

    2017-04-01

    Three novel coordination polymers, [Zn(sdi)2(NO3)(H2O)]·NO3 (1), [Zn(sdi)2(H2O)2]·2NO3 (2) and [Zn(sdi)0.5(H2C3O4)(H2O)] (3), (sdi = N,N‧-sulfuryldiimidazole) have been synthesized and characterized by elemental analysis, IR spectroscopy, single crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analyses. These compounds have abundant structural chemistry ranging from zero-dimensional (0D) (1), one-dimensional (1D) (2), to three-dimensional (3D) (3) networks. Compound 1 displays a 0D structure which formed by [Zn(sdi)2]2 dimers. Compound 2 possesses 1D chain with closed loops. Notably, compound 3 exhibits a 3D (3,4)-connected net with a (63)(65·8) topology. Interestingly, compounds 1-3 were obtained under similar reaction conditions and the structural diversity of these coordination polymers illustrate the remarkable effect of pH on the self-assembling process. Moreover, the fluorescent properties of these compounds have been investigated.

  4. Substituent effect of Fe(β-diketonate)3 on the control of self-assembly FePt-based nanoparticles

    Science.gov (United States)

    Chokprasombat, K.; Harding, P.; Sirisathitkul, C.; Tangwatanakul, W.; Pinitsoontorn, S.; Muneesawang, P.

    2014-06-01

    Three Fe(β-diketonate)3 compounds namely Fe(tmhd)3 (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionato), Fe(hfac)3 (hfac = hexafluoroacetylaceto), and Fe(dbm)3 (dbm = dibenzoylmethane) were used as substitutes to Fe(acac)3 (acac = acetyleacetonate) in the synthesis of FePt nanoparticles. The obtained superparamagnetic nanoparticles are 4-5 nm in diameter without showing a large size variation with substituent Fe(β-diketonate)3. The synchrotron X-ray absorption spectroscopy confirmed the energy dispersive spectroscopy that as-synthesized nanoparticles were composed of iron oxides and metallic FePt3 alloys. By employing Fe(hfac)3, the Fe fraction was reduced and the magnetization was modest. The use of Fe(dbm)3 as starting materials gave rise to densely packed FePt3/Fe2O3 heterodimers. The replacements of Fe(acac)3 by Fe(tmhd)3 led to the long-range order of nanoparticle assembly with the narrowest size distribution.

  5. Chemical bath deposition of ZnO on functionalized self-assembled monolayers: selective deposition and control of deposit morphology.

    Science.gov (United States)

    Shi, Zhiwei; Walker, Amy V

    2015-02-03

    We have developed a method by which to selectively and reproducibly deposit ZnO films on functionalized self-assembled monolayers (SAMs) using chemical bath deposition (CBD). The deposition bath is composed of zinc acetate and ethylenediamine. The deposition reaction pathways are shown to be similar to those observed for sulfides and selenides, even though ethylenediamine acts as both an oxygen source and a complexing agent. On -COOH terminated SAMs, Zn-carboxylate surface complexes act as nucleation sites for ion-by-ion growth, leading to the formation of adherent ZnO nanocrystallites. Cluster-by-cluster growth is also observed, which produces weakly adherent micrometer-sized ZnO crystallites. On -CH3 and -OH terminated SAMs, only micrometer-sized ZnO crystallites are observed because Zn(2+) does not complex with the SAM terminal group, preventing nucleation of the nanocrystalline phase. The application of either ultrasound ("sonication-assisted CBD") or stirring promotes ion-by-ion ZnO growth on -COOH terminated SAMs. Stirring produces smoother but less reproducible ZnO films than sonication-assisted CBD.

  6. On-Electrode Synthesis of Shape-Controlled Hierarchical Flower-Like Gold Nanostructures for Efficient Interfacial DNA Assembly and Sensitive Electrochemical Sensing of MicroRNA.

    Science.gov (United States)

    Su, Shao; Wu, Yan; Zhu, Dan; Chao, Jie; Liu, Xingfen; Wan, Ying; Su, Yan; Zuo, Xiaolei; Fan, Chunhai; Wang, Lianhui

    2016-07-01

    The performance for biomolecular detection is closely associated with the interfacial structure of a biosensor, which profoundly affects both thermodynamics and kinetics of the assembly, binding and signal transduction of biomolecules. Herein, it is reported on a one-step and template-free on-electrode synthesis method for making shape-controlled gold nanostructures on indium tin oxide substrates, which provide an electrochemical sensing platform for ultrasensitive detection of nucleic acids. Thus-prepared hierarchical flower-like gold nanostructures (HFGNs) possess large surface area that can readily accommodate the assembly of DNA probes for subsequent hybridization detection. It is found that the sensitivity for electrochemical DNA sensing is critically dependent on the morphology of HFGNs. By using this new strategy, a highly sensitive electrochemical biosensor is developed for label-free detection of microRNA-21 (miRNA-21), a biomarker for lung cancers. Importantly, it is demonstrated that this biosensor can be employed to measure the miRNA-21 expression level from human lung cancer cell (A549) lysates and worked well in 100% serum, suggesting its potential for applications in clinical diagnosis and a wide range of bioanalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A Collapsin Response Mediator Protein 2 Isoform Controls Myosin II-Mediated Cell Migration and Matrix Assembly by Trapping ROCK II

    Science.gov (United States)

    Morgan-Fisher, Marie; Wait, Robin; Couchman, John R.; Wewer, Ulla M.

    2012-01-01

    Collapsin response mediator protein 2 (CRMP-2) is known as a regulator of neuronal polarity and differentiation through microtubule assembly and trafficking. Here, we show that CRMP-2 is ubiquitously expressed and a splice variant (CRMP-2L), which is expressed mainly in epithelial cells among nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions through the inhibition of ROCK II in nonneuronal cells. PMID:22431514

  8. Controlled release studies of antimalarial 1, 3, 5-trisubstituted-2-pyrazolines from biocompatible chitosan-heparin Layer-by-Layer (LbL) self assembled thin films.

    Science.gov (United States)

    Bhalerao, Uma M; Valiveti, Aditya Kapil; Acharya, Jyotiranjan; Halve, Anand K; Kaushik, Mahabir Parshad

    2015-01-01

    Herein we report the in-vitro controlled release properties of 1, 3, 5-trisubstituted-2-pyrazolines through Layer-by-Layer (LbL) self assembled thin films fabricated from chitosan and heparin sodium salt as biocompatible polyelectrolytes. This study was carried out as a preliminary step towards the applicability of LbL technique in prophylactic drug delivery of antimalarial drugs. The growth of LbL self assembly was monitored by UV-Visible spectrophotometry and Quartz Crystal Microbalance (QCM). The loading as well as in-vitro release studies (in phosphate buffer saline at pH 7.4) were carried out using UV-Visible spectroscopy. Three compounds having good antimalarial activity were tested and the release rate was found inversely proportional to the hydrophobicity of the drug. Pzln-4 has shown best release among all the three compounds (up to 780 min) followed by Pzln-5 and Pzln-8. The release trend was that of a fast release up to first 2 h followed by a steady release. Kinetic fitting of the data confirmed the process of drug release followed a pseudo second order kinetics (R(2)≥0.99). A large value of rate constant (k) revealed a faster release. Pzln-4 has shown smallest value of k corresponding to slowest release among all the three compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Facile and controllable one-step fabrication of molecularly imprinted polymer membrane by magnetic field directed self-assembly for electrochemical sensing of glutathione.

    Science.gov (United States)

    Zhu, Wanying; Jiang, Guoyi; Xu, Lei; Li, Bingzhi; Cai, Qizhi; Jiang, Huijun; Zhou, Xuemin

    2015-07-30

    Based on magnetic field directed self-assembly (MDSA) of the ternary Fe3O4@PANI/rGO nanocomposites, a facile and controllable molecularly imprinted electrochemical sensor (MIES) was fabricated through a one-step approach for detection of glutathione (GSH). The ternary Fe3O4@PANI/rGO nanocomposites were obtained by chemical oxidative polymerization and intercalation of Fe3O4@PANI into the graphene oxide layers via π-π stacking interaction, followed by reduction of graphene oxide in the presence of hydrazine hydrate. In molecular imprinting process, the pre-polymers, including GSH as template molecule, Fe3O4@PANI/rGO nanocomposites as functional monomers and pyrrole as both cross-linker and co-monomer, was assembled through N-H hydrogen bonds and the electrostatic interaction, and then was rapidly oriented onto the surface of MGCE under the magnetic field induction. Subsequently, the electrochemical GSH sensor was formed by electropolymerization. In this work, the ternary Fe3O4@PANI/rGO nanocomposites could not only provide available functionalized sites in the matrix to form hydrogen bond and electrostatic interaction with GSH, but also afford a promoting network for electron transfer. Moreover, the biomimetic sensing membrane could be controlled more conveniently and effectively by adjusting the magnetic field strength. The as-prepared controllable sensor showed good stability and reproducibility for the determination of GSH with the detection limit reaching 3 nmol L(-1) (S/N = 3). In addition, the highly sensitive and selective biomimetic sensor has been successfully used for the clinical determination of GSH in biological samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Controller design for automatic micro-assembly systems under the influence of surface forces, hysteresis and quantizer

    NARCIS (Netherlands)

    Ouyang, Ruiyue; Jayawardhana, Bayu

    In this paper, we design nonlinear controllers for micro-magnetic levitation systems. The controller takes into account the influence of the surface forces and hysteresis/quantizer. We show the exponential convergence of the error signal and its time derivative to a compact set, which is determined

  11. General Assembly

    CERN Multimedia

    Staff Association

    2015-01-01

    Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : 1- Adoption de l’ordre du jour. 2- Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. 3- Présentation et approbation du rapport d’activités 2014. 4- Présentation et approbation du rapport financier 2014. 5- Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. 6- Programme 2015. 7- Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. 8- Pas de modifications aux Statuts de l'Association du personnel proposée. 9- Élections des membres de la Commission é...

  12. General assembly

    CERN Multimedia

    Staff Association

    2015-01-01

    Mardi 5 mai à 11 h 00 Salle 13-2-005 Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 22 mai 2014. Présentation et approbation du rapport d’activités 2014. Présentation et approbation du rapport financier 2014. Présentation et approbation du rapport des vérificateurs aux comptes pour 2014. Programme 2015. Présentation et approbation du projet de budget 2015 et taux de cotisation pour 2015. Pas de modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commission électorale. &am...

  13. General Assembly

    CERN Multimedia

    Staff Association

    2016-01-01

    Mardi 5 avril à 11 h 00 BE Auditorium Meyrin (6-2-024) Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 5 mai 2015. Présentation et approbation du rapport d’activités 2015. Présentation et approbation du rapport financier 2015. Présentation et approbation du rapport des vérificateurs aux comptes pour 2015. Programme de travail 2016. Présentation et approbation du projet de budget 2016 Approbation du taux de cotisation pour 2017. Modifications aux Statuts de l'Association du personnel proposée. Élections des membres de la Commissio...

  14. General Assembly

    CERN Multimedia

    Staff Association

    2017-01-01

    Conformément aux statuts de l’Association du personnel, une Assemblée générale ordinaire est organisée une fois par année (article IV.2.1). Projet d’ordre du jour : Adoption de l’ordre du jour. Approbation du procès-verbal de l’Assemblée générale ordinaire du 5 avril 2016. Présentation et approbation du rapport d’activités 2016. Présentation et approbation du rapport financier 2016. Présentation et approbation du rapport des vérificateurs aux comptes pour 2016. Programme de travail 2017. Présentation et approbation du projet de budget 2017 Approbation du taux de cotisation pour 2018. Modifications aux Statuts de l'Association du personnel proposées. Élections des membres de la Commission électorale. Élections des vérifica...

  15. Design principles for nonequilibrium self-assembly.

    Science.gov (United States)

    Nguyen, Michael; Vaikuntanathan, Suriyanarayanan

    2016-12-13

    We consider an important class of self-assembly problems, and using the formalism of stochastic thermodynamics, we derive a set of design principles for growing controlled assemblies far from equilibrium. The design principles constrain the set of configurations that can be obtained under nonequilibrium conditions. Our central result provides intuition for how equilibrium self-assembly landscapes are modified under finite nonequilibrium drive.

  16. Implementation and qualification of neutronic calculation methodology in subcritical reactors driven by external neutron sources and applications

    OpenAIRE

    Thiago Carluccio

    2011-01-01

    O trabalho teve como objetivo a investigação de Metodologias de Cálculo dos Reatores Subcríticos acionados por fonte externa de nêutrons, tais como, \\"Accelerator Driven Subcritical Reactor\\" (ADSR) e \\"Fusion Driven Subcritical Reator\\" (FDSR) , que são reatores nucleares subcríticos com uma fonte externa de nêutrons. Tais nêutrons são produzidos, no caso do ADSR, através da interação de partículas aceleradas (prótons, deutério) com um alvo (Pb, Bi, etc) ou através das reações de fusão, no c...

  17. Ginger and turmeric starches hydrolysis using subcritical water + CO2: the effect of the SFE pre-treatment

    Directory of Open Access Journals (Sweden)

    S. R. M. Moreschi

    2006-06-01

    Full Text Available In this work, the hydrolysis of fresh and dried turmeric (Curcuma longa L. and ginger (Zingiber officinale R. in the presence of subcritical water + CO2 was studied. The hydrolysis of ginger and turmeric bagasses from supercritical fluid extraction was also studied. The reactions were done using subcritical water and CO2 at 150 bar, 200 °C and reaction time of 11 minutes; the degree of reaction was monitored through the amount of starch hydrolyzed. Process yields were calculated using the amount of reducing and total sugars formed. The effects of supercritical fluid extraction in the starchy structures were observed by scanning electron microscopy. Higher degree of hydrolysis (97- 98 % were obtained for fresh materials and the highest total sugar yield (74% was established for ginger bagasse. The supercritical fluid extraction did not significantly modify the degree of hydrolysis in the tested conditions.

  18. Application of the Modified Source Multiplication (MSM) Technique to Subcritical Reactivity Worth Measurements in Thermal and Fast Reactor Systems

    Science.gov (United States)

    Blaise, Patrick; Mellier, Frédéric; Fougeras, Philippe

    2011-06-01

    The Amplified Source Multiplication (ASM) method and its improved Modified Source Multiplication (MSM) method have been widely used in the CEA's EOLE and MASURCA critical facilities over the past decades for the determination of reactivity worths by using fission chambers in subcritical configurations. The ASM methodology uses relatively simple relationships between count rates of efficient miniature fission chambers located in slightly subcritical reference and perturbed configurations. While this method works quite well for small reactivity variations, the raw results need to be corrected to take into account the flux perturbation at the fission chamber location. This is performed by applying to the measurement a correction factor called MSM. This paper describes in detail both methodologies, with their associated uncertainties. Applications on absorber cluster worth in the MISTRAL-4 full MOX mock-up core and the last core loaded in MASURCA show the importance of the MSM correction on raw ASM data.

  19. Crystalline orientation control using self-assembled TiO2 nanosheet scaffold to improve CH3NH3PbI3 perovskite solar cells

    Science.gov (United States)

    Maitani, Masato M.; Satou, Hirokazu; Ohmura, Aoi; Tsubaki, Shuntaro; Wada, Yuji

    2017-08-01

    In perovskite solar cells with an organic inorganic hybrid metal halide perovskite crystalline semiconductor as the active layer, the properties of the n-type semiconductor scaffold, the materials used, and the morphology, wettability, and surface reactivity of the cells are important decisive factors affecting the overall device efficiency of the perovskite solar cells. We control the orientation of anatase titania nanosheets by a self-assembly technique to create the ordered mesoporous scaffolds with ordered voids. Differences between nanosheet orientations in each mesoporous scaffold indicate differences in the photoelectric properties of CH3NH3PbI3 perovskite crystals embedded in each scaffold. Although each scaffold consists of the same anatase TiO2 nanosheets, the properties of the solar cells are affected by the oxide scaffold nanomorphology, which determines the growth orientation of CH3NH3PbI3 perovskite crystals that affects the solar cell properties.

  20. Active phase locking of a tiled two-grating assembly for high-energy laser pulse compression using simultaneous controls from far-field profiles and interferometry

    Science.gov (United States)

    Sharma, A. K.; Joshi, A. S.; Naik, P. A.; Gupta, P. D.

    2017-04-01

    A prototype study on active phase locking of a tiled two-grating assembly (TTGA) using four electronic nanometric actuators has been reported, for its use in high-energy laser pulse compression. Measurement and correction of various phase errors of a TTGA have been demonstrated with a precision of sub-50 nm in differential longitudinal translational and sub-10 µrad in differential angular errors using controls derived from simultaneous recording of laser interferogram and far-field profiles of reflected and diffracted beams from TTGA differentiating in-plane rotation with respect to tip error, which is otherwise difficult in the case of using interferometry alone. Multiple-level intensities in the thresholds of the power spectra of apodized interferogram and far-field profiles have been adapted to estimate spatial frequencies and beam peak positions with sub-pixel accuracies.

  1. A collapsin response mediator protein 2 isoform controls myosin II-mediated cell migration and matrix assembly by trapping ROCK II

    DEFF Research Database (Denmark)

    Yoneda, Atsuko; Morgan-Fisher, Marie; Wait, Robin

    2012-01-01

    nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two...... binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP......-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions...

  2. Analysis of the Temporal Response of Coupled Asymmetrical Zero-Power Subcritical Bare Metal Reactor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Klain, Kimberly L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-21

    The behavior of symmetrical coupled-core systems has been extensively studied, yet there is a dearth of research on asymmetrical systems due to the increased complexity of the analysis of such systems. In this research, the multipoint kinetics method is applied to asymmetrical zeropower, subcritical, bare metal reactor systems. Existing research on asymmetrical reactor systems assumes symmetry in the neutronic coupling; however, it will be shown that this cannot always be assumed. Deep subcriticality adds another layer of complexity and requires modification of the multipoint kinetics equations to account for the effect of the external neutron source. A modified set of multipoint kinetics equations is derived with this in mind. Subsequently, the Rossi-alpha equations are derived for a two-region asymmetrical reactor system. The predictive capabilities of the radiation transport code MCNP6 for neutron noise experiments are shown in a comparison to the results of a series of Rossi-alpha measurements performed by J. Mihalczo utilizing a coupled set of symmetrical bare highly-enriched uranium (HEU) cylinders. The ptrac option within MCNP6 can generate time-tagged counts in a cell (list-mode data). The list-mode data can then be processed similarly to measured data to obtain values for system parameters such as the dual prompt neutron decay constants observable in a coupled system. The results from the ptrac simulations agree well with the historical measured values. A series of case studies are conducted to study the effects of geometrical asymmetry in the coupling between two bare metal HEU cylinders. While the coupling behavior of symmetrical systems has been reported on extensively, that of asymmetrical systems remains sparse. In particular, it appears that there has been no previous research in obtaining the coupling time constants for asymmetrically-coupled systems. The difficulty in observing such systems is due in part to the inability to determine the

  3. Recovery of solid fuel from municipal solid waste by hydrothermal treatment using subcritical water

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, In-Hee, E-mail: hwang@eng.hokudai.ac.jp [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan); Aoyama, Hiroya; Matsuto, Toshihiko; Nakagishi, Tatsuhiro; Matsuo, Takayuki [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Hydrothermal treatment using subcritical water was studied to recover solid fuel from MSW. Black-Right-Pointing-Pointer More than 75% of carbon in MSW was recovered as char. Black-Right-Pointing-Pointer Heating value of char was comparable to that of brown coal and lignite. Black-Right-Pointing-Pointer Polyvinyl chloride was decomposed at 295 Degree-Sign C and 8 MPa and was removed by washing. - Abstract: Hydrothermal treatments using subcritical water (HTSW) such as that at 234 Degree-Sign C and 3 MPa (LT condition) and 295 Degree-Sign C and 8 MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources. While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char. Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing. From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel.

  4. Extraction of Fenugreek (Trigonella foenum-graceum L.) Seed Oil Using Subcritical Butane: Characterization and Process Optimization.

    Science.gov (United States)

    Gu, Ling-Biao; Liu, Xiao-Ning; Liu, Hua-Min; Pang, Hui-Li; Qin, Guang-Yong

    2017-02-02

    In this study, the subcritical butane extraction process of fenugreek seed oil was optimized using response surface methodology with a Box-Behnken design. The optimum conditions for extracted oil from fenugreek seed was as follows: extraction temperature of 43.24 °C , extraction time of 32.80 min, and particle size of 0.26 mm. No significant differences were found between the experimental and predicted values. The physical and chemical properties of the oil showed that the oil could be used as edible oil. Fatty acid composition of oils obtained by subcritical butane under the optimum conditions and by accelerated solvent extraction showed negligible difference. The oils were rich in linoleic acid (42.71%-42.80%), linolenic acid (26.03%-26.15%), and oleic acid (14.24%-14.40%). The results revealed that the proposed method was feasible, and this essay shows the way to exploit fenugreek seeds by subcritical butane extraction under the scope of edible oils.

  5. Rotary shaft sealing assembly

    Science.gov (United States)

    Dietle, Lannie L.; Schroeder, John E.; Kalsi, Manmohan S.; Alvarez, Patricio D.

    2010-09-21

    A rotary shaft sealing assembly in which a first fluid is partitioned from a second fluid in a housing assembly having a rotary shaft located at least partially within. In one embodiment a lip seal is lubricated and flushed with a pressure-generating seal ring preferably having an angled diverting feature. The pressure-generating seal ring and a hydrodynamic seal may be used to define a lubricant-filled region with each of the seals having hydrodynamic inlets facing the lubricant-filled region. Another aspect of the sealing assembly is having a seal to contain pressurized lubricant while withstanding high rotary speeds. Another rotary shaft sealing assembly embodiment includes a lubricant supply providing a lubricant at an elevated pressure to a region between a lip seal and a hydrodynamic seal with a flow control regulating the flow of lubricant past the lip seal. The hydrodynamic seal may include an energizer element having a modulus of elasticity greater than the modulus of elasticity of a sealing lip of the hydrodynamic seal.

  6. Ordered Assembly and Controlled Electron Transfer of the Blue Copper Protein Azurin at Gold (111) Single-Crystal Substrates

    DEFF Research Database (Denmark)

    Chi, Qijin; Zhang, Jingdong; Andersen, Jens Enevold Thaulov

    2001-01-01

    investigated by different electrochemical techniques. Distance-dependent ET can be controlled by adjusting the length of the alkanethiol chain. The electrochemical ET rate constant is almost independent of the chain length up to ca. 9 methylene units but follows exponential distance decay with a decay factor...

  7. Peptide-Assembled Optically Responsive Nanoparticle Complexes

    National Research Council Canada - National Science Library

    Slocik, Joseph M; Tam, Felicia; Halas, Naomi J; Naik, Rajesh R

    2007-01-01

    .... Here we report two types of active nanoparticle complexes, with properties controlled by near-infrared illumination, resulting from the assembly of photothermally responsive plasmonic nanoparticle...

  8. CFD Analysis and Design of Detailed Target Configurations for an Accelerator-Driven Subcritical System

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Adam; Merzari, Elia; Sofu, Tanju; Zhong, Zhaopeng; Gohar, Yousry

    2016-08-01

    High-fidelity analysis has been utilized in the design of beam target options for an accelerator driven subcritical system. Designs featuring stacks of plates with square cross section have been investigated for both tungsten and uranium target materials. The presented work includes the first thermal-hydraulic simulations of the full, detailed target geometry. The innovative target cooling manifold design features many regions with complex flow features, including 90 bends and merging jets, which necessitate three-dimensional fluid simulations. These were performed using the commercial computational fluid dynamics code STAR-CCM+. Conjugate heat transfer was modeled between the plates, cladding, manifold structure, and fluid. Steady-state simulations were performed but lacked good residual convergence. Unsteady simulations were then performed, which converged well and demonstrated that flow instability existed in the lower portion of the manifold. It was established that the flow instability had little effect on the peak plate temperatures, which were well below the melting point. The estimated plate surface temperatures and target region pressure were shown to provide sufficient margin to subcooled boiling for standard operating conditions. This demonstrated the safety of both potential target configurations during normal operation.

  9. Recycling high-performance carbon fiber reinforced polymer composites using sub-critical and supercritical water

    Science.gov (United States)

    Knight, Chase C.

    Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown

  10. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces.

    Science.gov (United States)

    Carmichael, Justin R; Rother, Gernot; Browning, James F; Ankner, John F; Banuelos, Jose L; Anovitz, Lawrence M; Wesolowski, David J; Cole, David R

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO(2) in contact with quartz and Si/SiO(2) wafers are also shown. © 2012 American Institute of Physics

  11. Complete degradation of Orange G by electrolysis in sub-critical water.

    Science.gov (United States)

    Yuksel, Asli; Sasaki, Mitsuru; Goto, Motonobu

    2011-06-15

    Complete degradation of azo dye Orange G was studied using a 500 mL continuous flow reactor made of SUS 316 stainless steel. In this system, a titanium reactor wall acted as a cathode and a titanium plate-type electrode was used as an anode in a subcritical reaction medium. This hydrothermal electrolysis process provides an environmentally friendly route that does not use any organic solvents or catalysts to remove organic pollutants from wastewater. Reactions were carried out from 30 to 90 min residence times at a pressure of 7 MPa, and at different temperatures of 180-250°C by applying various direct currents ranging from 0.5 to 1A. Removal of dye from the product solution and conversion of TOC increased with increasing current value. Moreover, the effect of salt addition on degradation of Orange G and TOC conversion was investigated, because in real textile wastewater, many salts are also included together with dye. Addition of Na(2)CO(3) resulted in a massive degradation of the dye itself and complete mineralization of TOC, while NaCl and Na(2)SO(4) obstructed the removal of Orange G. Greater than 99% of Orange G was successfully removed from the product solution with a 98% TOC conversion. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

    Directory of Open Access Journals (Sweden)

    Kurian V. J.

    2017-01-01

    Full Text Available Vortex Induced Vibrations (VIV may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP, Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT. VIVFT is a two degree of freedom (2DOF forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes.

  13. Hydrothermal liquefaction of Spirulina and Nannochloropsis salina under subcritical and supercritical water conditions.

    Science.gov (United States)

    Toor, Saqib S; Reddy, Harvind; Deng, Shuguang; Hoffmann, Jessica; Spangsmark, Dorte; Madsen, Linda B; Holm-Nielsen, Jens Bo; Rosendahl, Lasse A

    2013-03-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220–375 °C, 20–255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid residue, and recycling process water for algae cultivation. GC–MS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained on N. salina at 350 °C and 175 bar. For S. platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for N. salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Energy conversion of biomass with supercritical and subcritical water using large-scale plants.

    Science.gov (United States)

    Okajima, Idzumi; Sako, Takeshi

    2014-01-01

    Exploiting unused or waste biomass as an alternative fuel is currently receiving much attention because of the potential reductions in CO2 emissions and the lower cost in comparison to expensive fossil fuels. If we are to use biomass domestically or industrially, we must be able to convert biomass to high-quality and easy-to-use liquid, gas, or solid fuels that have high-calorific values, low moisture and ash contents, uniform composition, and suitable for stored over long periods. In biomass treatment, hot and high-pressure water including supercritical and subcritical water is an excellent solvent, as it is clean and safe and its action on biomass can be optimized by varying the temperature and pressure. In this article, the conversion of waste biomass to fuel using hot and high-pressure water is reviewed, and the following examples are presented: the production of large amounts of hydrogen from waste biomass, the production of cheap bioethanol from non-food raw materials, and the production of composite powder fuel from refractory waste biomass in the rubble from the Great East Japan Earthquake. Several promising techniques for the conversion of biomass have been demonstrated in large-scale plants and commercial deployment is expected in the near future. Copyright © 2013. Published by Elsevier B.V.

  15. Subcritical Butane Extraction of Wheat Germ Oil and Its Deacidification by Molecular Distillation

    Directory of Open Access Journals (Sweden)

    Jinwei Li

    2016-12-01

    Full Text Available Extraction and deacidification are important stages for wheat germ oil (WGO production. Crude WGO was extracted using subcritical butane extraction (SBE and compared with traditional solvent extraction (SE and supercritical carbon dioxide extraction (SCE based on the yield, chemical index and fatty acid profile. Furthermore, the effects of the molecular distillation temperature on the quality of WGO were also investigated in this study. Results indicated that WGO extracted by SBE has a higher yield of 9.10% and better quality; at the same time, its fatty acid composition has no significant difference compared with that of SE and SCE. The molecular distillation experiment showed that the acid value, peroxide value and p-anisidine value of WGO were reduced with the increase of the evaporation temperatures, and the contents of the active constituents of tocopherol, polyphenols and phytosterols are simultaneously decreased. Generally, the distillation temperature of 150 °C is an appropriate condition for WGO deacidification with the higher deacidification efficiency of 77.78% and the higher retention rate of active constituents.

  16. Studies on subcritical and overcritical density laser ablated TAC foam targets

    Science.gov (United States)

    Chaurasia, S.; Leshma, P.; Murali, C. G.; Borisenko, N. G.; Munda, D. S.; Orekhov, A.; Gromov, A. I.; Merkuliev, Yu. A.; Dhareshwar, L. J.

    2015-05-01

    In this paper, the interaction of high power laser with low density polymer foam with density as low as 2 mg/cm3, 4 mg/cm3, 20 mg/cm3 30 mg/cm3 and 50 mg/cm3 targets are investigated and compared with solid polymer targets. An understanding of such interaction is important from fusion research point of view. Low density foam coating of fusion capsule has been proposed in order to smooth in direct drive scheme and also it is being used as efficient x-ray converter in indirect drive scheme. It is observed that about 75-80% of the laser energy is absorbed in the subcritical (with density case is almost two times that measured in the over dense (supper critical) targets. The optical shadowgraphy of the targets shows that the laser coupling in low density foam is associated with a supersonic heat wave while, with increasing density this phenomenon is replaced by subsonic absorption and shock formation. In the case of a 50 mg/cm3 foams the foil velocity reduced by 35% (i.e. 5×106 cm/s), which further reduced to 3.8×106 cm/s in case solid polymer targets.

  17. Particle formation of budesonide from alcohol-modified subcritical water solutions.

    Science.gov (United States)

    Carr, Adam G; Mammucari, Raffaella; Foster, Neil R

    2011-02-28

    Recently, subcritical water (SBCW: water that has been heated to a temperature between 100°C and 200°C at pressures of up to 70bar) has been used to dissolve several hydrophobic pharmaceutical compounds (Carr et al., 2010a). Furthermore, a number of active pharmaceutical ingredients (APIs) have been rapidly precipitated from SBCW solutions (Carr et al., 2010b,c). It is possible to alter the precipitate morphology by altering the processing variables; including the SBCW-API solution injection temperature and adding impurities (such as pharmaceutical excipients, e.g. lactose) to the precipitation chamber. The work presented in this article demonstrates that the morphology of pharmaceutical particles can be tuned by adding organic solvents (ethanol and methanol) to the SBCW-API solutions. Particle morphology has also been tuned by adding different pharmaceutical excipients (polyethylene glycol 400 and lactose) to the precipitation chamber. Different morphologies of pharmaceutical particles were produced, ranging from nanospheres of 60nm diameter to 5μm plate particles. Budesonide was used as the model API in this study. Two experimental products were spray dried to form dry powder products. The aerodynamic particle size of the powder was established by running the powder through an Andersen Cascade Impactor. It has been shown that the drug particles produced from the SBCW micronization process, when coupled with a spray drying process, are suitable for delivery to the lungs. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, John K.

    2009-11-01

    Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

  19. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces

    Science.gov (United States)

    Carmichael, Justin R.; Rother, Gernot; Browning, James F.; Ankner, John F.; Banuelos, Jose L.; Anovitz, Lawrence M.; Wesolowski, David J.; Cole, David R.

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.

  20. Subcritical water extraction and characterization of bioactive compounds from Haematococcus pluvialis microalga.

    Science.gov (United States)

    Rodríguez-Meizoso, I; Jaime, L; Santoyo, S; Señoráns, F J; Cifuentes, A; Ibáñez, E

    2010-01-20

    In this work, extraction and characterization of compounds with antioxidant and antimicrobial activity from Haematococcus pluvialis microalga in red phase have been carried out. To do this, subcritical water extraction (SWE) has been combined with analytical techniques such as HPLC-DAD, HPLC-QqQ-MS and GC-MS and in vitro assays (i.e., for antioxidant and antimicrobial activity). The effect of the extraction temperature (50, 100, 150 and 200 degrees C) and solvent polarity has been studied in terms of yield and activity of the extracts. Results demonstrate that the extraction temperature has a positive influence in the extraction yield and antioxidant activity. Thus, the extraction yield achieved with this process was higher than 30% of dry weight at 200 degrees C as extraction temperature. Moreover, the extract obtained at 200 degrees C presented the highest antioxidant activity by far, while temperature does not seem to significatively affect the antimicrobial activity. Chemical composition was determined by HPLC-DAD, HPLC-QqQ-MS and GC-MS. Short chain fatty acids turned out to be responsible of the antimicrobial activity, whereas the antioxidant activity was correlated to vitamin E (present exclusively in the 200 degrees C extract), together with simple phenols, caramelization products and possible Maillard reaction products obtained during the extraction at high temperatures.