WorldWideScience

Sample records for quantum yield convention

  1. Investigating energy partitioning during photosynthesis using an expanded quantum yield convention

    Science.gov (United States)

    Ahn, Tae Kyu; Avenson, Thomas J.; Peers, Graham; Li, Zhirong; Dall'Osto, Luca; Bassi, Roberto; Niyogi, Krishna K.; Fleming, Graham R.

    2009-02-01

    In higher plants, regulation of excess absorbed light is essential for their survival and fitness, as it enables avoidance of a build up of singlet oxygen and other reactive oxygen species. Regulation processes (known as non-photochemical quenching; NPQ) can be monitored by steady-state fluorescence on intact plant leaves. Pulse amplitude modulated (PAM) measurements of chlorophyll a fluorescence have been used for over 20 years to evaluate the amount of NPQ and photochemistry (PC). Recently, a quantum yield representation of NPQ ( ΦNPQ), which incorporates a variable fraction of open reaction centers, was proposed by Hendrickson et al. [L. Hendrickson, R.T. Furbank, W.S. Chow, Photosynth. Res. 82 (2004) 73]. In this work we extend the quantum yield approach to describe the yields of reversible energy-dependent quenching ( ΦqE), state transitions to balance PC between photosystems II and I ( ΦqT), and photoinhibition quenching associated with damaged reaction centers ( ΦqI). We showed the additivity of the various quantum yield components of NPQ through experiments on wild-type and npq1 strains of Arabidopsis thaliana. The quantum yield approach enables comparison of ΦqE with data from a variety of techniques used to investigate the mechanism of qE. We showed that ΦqE for a series of A. thaliana genotypes scales linearly with the magnitude of zeaxanthin cation formation, suggesting that charge-transfer quenching is largely responsible for qE in plants.

  2. Investigating energy partitioning during photosynthesis using an expanded quantum yield convention

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Tae Kyu [Department of Chemistry, Hildebrand B77, University of California, Berkeley, CA 94720-1460 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Avenson, Thomas J. [Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102 (United States); Peers, Graham; Li Zhirong [Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102 (United States); Dall' Osto, Luca; Bassi, Roberto [Department of Science and Technology, University of Verona, Verona 37134 (Italy); Niyogi, Krishna K. [Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102 (United States)], E-mail: niyogi@nature.berkeley.edu; Fleming, Graham R. [Department of Chemistry, Hildebrand B77, University of California, Berkeley, CA 94720-1460 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: GRFleming@lbl.gov

    2009-02-23

    In higher plants, regulation of excess absorbed light is essential for their survival and fitness, as it enables avoidance of a build up of singlet oxygen and other reactive oxygen species. Regulation processes (known as non-photochemical quenching; NPQ) can be monitored by steady-state fluorescence on intact plant leaves. Pulse amplitude modulated (PAM) measurements of chlorophyll a fluorescence have been used for over 20 years to evaluate the amount of NPQ and photochemistry (PC). Recently, a quantum yield representation of NPQ ({phi}{sub NPQ}), which incorporates a variable fraction of open reaction centers, was proposed by Hendrickson et al. [L. Hendrickson, R.T. Furbank, W.S. Chow, Photosynth. Res. 82 (2004) 73]. In this work we extend the quantum yield approach to describe the yields of reversible energy-dependent quenching ({phi}{sub qE}), state transitions to balance PC between photosystems II and I ({phi}{sub qT}), and photoinhibition quenching associated with damaged reaction centers ({phi}{sub qI}). We showed the additivity of the various quantum yield components of NPQ through experiments on wild-type and npq1 strains of Arabidopsis thaliana. The quantum yield approach enables comparison of {phi}{sub qE} with data from a variety of techniques used to investigate the mechanism of qE. We showed that {phi}{sub qE} for a series of A. thaliana genotypes scales linearly with the magnitude of zeaxanthin cation formation, suggesting that charge-transfer quenching is largely responsible for qE in plants.

  3. Comparing the yields of organic and conventional agriculture.

    Science.gov (United States)

    Seufert, Verena; Ramankutty, Navin; Foley, Jonathan A

    2012-05-10

    Numerous reports have emphasized the need for major changes in the global food system: agriculture must meet the twin challenge of feeding a growing population, with rising demand for meat and high-calorie diets, while simultaneously minimizing its global environmental impacts. Organic farming—a system aimed at producing food with minimal harm to ecosystems, animals or humans—is often proposed as a solution. However, critics argue that organic agriculture may have lower yields and would therefore need more land to produce the same amount of food as conventional farms, resulting in more widespread deforestation and biodiversity loss, and thus undermining the environmental benefits of organic practices. Here we use a comprehensive meta-analysis to examine the relative yield performance of organic and conventional farming systems globally. Our analysis of available data shows that, overall, organic yields are typically lower than conventional yields. But these yield differences are highly contextual, depending on system and site characteristics, and range from 5% lower organic yields (rain-fed legumes and perennials on weak-acidic to weak-alkaline soils), 13% lower yields (when best organic practices are used), to 34% lower yields (when the conventional and organic systems are most comparable). Under certain conditions—that is, with good management practices, particular crop types and growing conditions—organic systems can thus nearly match conventional yields, whereas under others it at present cannot. To establish organic agriculture as an important tool in sustainable food production, the factors limiting organic yields need to be more fully understood, alongside assessments of the many social, environmental and economic benefits of organic farming systems.

  4. Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation.

    Science.gov (United States)

    Orfield, Noah J; McBride, James R; Wang, Feng; Buck, Matthew R; Keene, Joseph D; Reid, Kemar R; Htoon, Han; Hollingsworth, Jennifer A; Rosenthal, Sandra J

    2016-02-23

    Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. Herein, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking "giant" CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging, rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive "dark" fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be "dark". Therefore, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.

  5. The crop yield gap between organic and conventional agriculture

    NARCIS (Netherlands)

    Ponti, de T.; Rijk, H.C.A.; Ittersum, van M.K.

    2012-01-01

    A key issue in the debate on the contribution of organic agriculture to the future of world agriculture is whether organic agriculture can produce sufficient food to feed the world. Comparisons of organic and conventional yields play a central role in this debate. We therefore compiled and analyzed

  6. The crop yield gap between organic and conventional agriculture

    NARCIS (Netherlands)

    Ponti, de T.; Rijk, H.C.A.; Ittersum, van M.K.

    2012-01-01

    A key issue in the debate on the contribution of organic agriculture to the future of world agriculture is whether organic agriculture can produce sufficient food to feed the world. Comparisons of organic and conventional yields play a central role in this debate. We therefore compiled and analyzed

  7. Diversification practices reduce organic to conventional yield gap.

    Science.gov (United States)

    Ponisio, Lauren C; M'Gonigle, Leithen K; Mace, Kevi C; Palomino, Jenny; de Valpine, Perry; Kremen, Claire

    2015-01-22

    Agriculture today places great strains on biodiversity, soils, water and the atmosphere, and these strains will be exacerbated if current trends in population growth, meat and energy consumption, and food waste continue. Thus, farming systems that are both highly productive and minimize environmental harms are critically needed. How organic agriculture may contribute to world food production has been subject to vigorous debate over the past decade. Here, we revisit this topic comparing organic and conventional yields with a new meta-dataset three times larger than previously used (115 studies containing more than 1000 observations) and a new hierarchical analytical framework that can better account for the heterogeneity and structure in the data. We find organic yields are only 19.2% (±3.7%) lower than conventional yields, a smaller yield gap than previous estimates. More importantly, we find entirely different effects of crop types and management practices on the yield gap compared with previous studies. For example, we found no significant differences in yields for leguminous versus non-leguminous crops, perennials versus annuals or developed versus developing countries. Instead, we found the novel result that two agricultural diversification practices, multi-cropping and crop rotations, substantially reduce the yield gap (to 9 ± 4% and 8 ± 5%, respectively) when the methods were applied in only organic systems. These promising results, based on robust analysis of a larger meta-dataset, suggest that appropriate investment in agroecological research to improve organic management systems could greatly reduce or eliminate the yield gap for some crops or regions.

  8. Quantum Yield Characterization and Excitation Scheme Optimization of Upconverting Nanoparticles

    DEFF Research Database (Denmark)

    Liu, Haichun; Xu, Can T.; Jensen, Ole Bjarlin

    2014-01-01

    Upconverting nanoparticles suffer from low quantum yield in diffuse optical imaging, especially at low excitation intensities. Here, the power density dependent quantum yield is characterized, and the excitation scheme is optimized based on such characterization......Upconverting nanoparticles suffer from low quantum yield in diffuse optical imaging, especially at low excitation intensities. Here, the power density dependent quantum yield is characterized, and the excitation scheme is optimized based on such characterization...

  9. Quantum Yield Characterization and Excitation Scheme Optimization of Upconverting Nanoparticles

    DEFF Research Database (Denmark)

    Liu, Haichun; Xu, Can T.; Jensen, Ole Bjarlin;

    2014-01-01

    Upconverting nanoparticles suffer from low quantum yield in diffuse optical imaging, especially at low excitation intensities. Here, the power density dependent quantum yield is characterized, and the excitation scheme is optimized based on such characterization......Upconverting nanoparticles suffer from low quantum yield in diffuse optical imaging, especially at low excitation intensities. Here, the power density dependent quantum yield is characterized, and the excitation scheme is optimized based on such characterization...

  10. Critique of Conventional Relativistic Quantum Mechanics.

    Science.gov (United States)

    Fanchi, John R.

    1981-01-01

    Following an historical sketch of the development of relativistic quantum mechanics, a discussion of the still unresolved difficulties of the currently accepted theories is presented. This review is designed to complement and update the discussion of relativistic quantum mechanics presented in many texts used in college physics courses. (Author/SK)

  11. Quantum Phase Transitions in Conventional Matrix Product Systems

    Science.gov (United States)

    Zhu, Jing-Min; Huang, Fei; Chang, Yan

    2017-02-01

    For matrix product states(MPSs) of one-dimensional spin-1/2 chains, we investigate a new kind of conventional quantum phase transition(QPT). We find that the system has two different ferromagnetic phases; on the line of the two ferromagnetic phases coexisting equally, the system in the thermodynamic limit is in an isolated mediate-coupling state described by a paramagnetic state and is in the same state as the renormalization group fixed point state, the expectation values of the physical quantities are discontinuous, and any two spin blocks of the system have the same geometry quantum discord(GQD) within the range of open interval (0,0.25) and the same classical correlation(CC) within the range of open interval (0,0.75) compared to any phase having no any kind of correlation. We not only realize the control of QPTs but also realize the control of quantum correlation of quantum many-body systems on the critical line by adjusting the environment parameters, which may have potential application in quantum information fields and is helpful to comprehensively and deeply understand the quantum correlation, and the organization and structure of quantum correlation especially for long-range quantum correlation of quantum many-body systems.

  12. Topological quantum buses: coherent quantum information transfer between topological and conventional qubits

    CERN Document Server

    Bonderson, Parsa

    2010-01-01

    We propose computing bus devices that enable quantum information to be coherently transferred between topological and conventional qubits. We describe a concrete realization of such a topological quantum bus acting between a topological qubit in a Majorana wire network and a conventional semiconductor double quantum dot qubit. Specifically, this device measures the joint (fermion) parity of these two different qubits by using the Aharonov-Casher effect in conjunction with an ancilliary superconducting flux qubit that facilitates the measurement. Such a parity measurement, together with the ability to apply Hadamard gates to the two qubits, allows one to produce states in which the topological and conventional qubits are maximally entangled and to teleport quantum states between the topological and conventional quantum systems.

  13. Topological Quantum Buses: Coherent Quantum Information Transfer between Topological and Conventional Qubits

    Science.gov (United States)

    Bonderson, Parsa; Lutchyn, Roman M.

    2011-04-01

    We propose computing bus devices that enable quantum information to be coherently transferred between topological and conventional qubits. We describe a concrete realization of such a topological quantum bus acting between a topological qubit in a Majorana wire network and a conventional semiconductor double quantum dot qubit. Specifically, this device measures the joint (fermion) parity of these two different qubits by using the Aharonov-Casher effect in conjunction with an ancilliary superconducting flux qubit that facilitates the measurement. Such a parity measurement, together with the ability to apply Hadamard gates to the two qubits, allows one to produce states in which the topological and conventional qubits are maximally entangled and to teleport quantum states between the topological and conventional quantum systems.

  14. The Glueball Spectrum In Conventional And Supersymmetric Quantum Chromodynamics

    CERN Document Server

    Gabadadze, Gregory T

    1998-01-01

    In the Dissertation we study some nonperturbative aspects of conventional Quantum Chromodynamics and its minimal supersymmetric counterpart, supersymmetric gluodynamics. After the introduction, the discussion of the spectrum of lightest glueballs in Quantum Chromodynamics is given. It is shown that the pseudoscalar glueball mass in Quantum Chromodynamics is less than the mass obtained in quenched lattice calculations. The glueball mass and nonperturbative glueball matrix elements are calculated. The production rate for the pseudoscalar glueball in radiative decays is predicted. Then, we study the nonperturbative features of the Lagrangian of Quantum Chromodynamics which might be responsible for formation of the pseudoscalar glueball state. The issue of the screening of the topological charge is analyzed. A possible non-perturbative mechanism of formation of the pseudoscalar glueball state is proposed. The masses of lowest pseudoscalar glueballs are predicted within the framework of this approach. The second h...

  15. Comparison of Surface Water Quality and Yields from Organically and Conventionally Produced Sweet Corn Plots with Conservation and Conventional Tillage.

    Science.gov (United States)

    Edgell, Joshua; Osmond, D L; Line, D E; Hoyt, G D; Grossman, J M; Larsen, E M

    2015-11-01

    Organic agricultural systems are often assumed to be more sustainable than conventional farming, yet there has been little work comparing surface water quality from organic and conventional production, especially under the same cropping sequence. Our objective was to compare nutrient and sediment losses, as well as sweet corn ( L. var. ) yield, from organic and conventional production with conventional and conservation tillage. The experiment was located in the Appalachian Mountains of North Carolina. Four treatments, replicated four times, had been in place for over 18 yr and consisted of conventional tillage (chisel plow and disk) with conventional production (CT/Conven), conservation no-till with conventional production (NT/Conven), conventional tillage with organic production (CT/Org), and conservation no-till with organic production (NT/Org). Water quality (surface flow volume; nitrogen, phosphorus, and sediment concentrations) and sweet corn yield data were collected in 2011 and 2012. Sediment and sediment-attached nutrient losses were influenced by tillage and cropping system in 2011, due to higher rainfall, and tillage in 2012. Soluble nutrients were affected by the nutrient source and rate, which are a function of the cropping system. Sweet corn marketable yields were greater in conventional systems due to high weed competition and reduced total nitrogen availability in organic treatments. When comparing treatment efficiency (yield kg ha /nutrient loss kg ha ), the NT/Conven treatment had the greatest sweet corn yield per unit of nutrient and sediment loss. Other treatment ratios were similar to each other; thus, it appears the most sustainably productive treatment was NT/Conven.

  16. Coherent and conventional gravidynamic quantum 1/f noise

    Science.gov (United States)

    Handel, Peter H.; George, Thomas F.

    2008-04-01

    Quantum 1/f noise is a fundamental fluctuation of currents, physical cross sections or process rates, caused by infrared coupling of the current carriers to very low frequency (soft) quanta, also known as infraquanta. The latter are soft gravitons in the gravidynamic case with the coupling constant g= pGM2/Nch considered here -- soft photons in the electrodynamic case and soft transversal piezo-phonons in the lattice-dynamical case. Here p=3.14 and F=psi. Quantum 1/f noise is a new aspect of quantum mechanics expressed mainly through the coherent quantum 1/f effect 2g/pf derived here for large systems, and mainly through the conventional quantum 1/f effect for small systems or individual particles. Both effects are present in general, and their effects are superposed in a first approximation with the help of a coherence (weight) parameter s" that will be derived elsewhere for the gravitational case. The spectral density of fractional fluctuations S(dj/j,f) for j=e(hk/2pm)|F|2 is S(F2,f)/ = S(j,f)/2 = [4ps"/(1+s")]GM2/pfNch = 4.4 10E9 M2/(pfNgram2). Here s" = 2N'GM/c2=N'rs, where N' is the number of particles of mass M per unit length of the current, rs their Schwarzschild radius, and s" is our coherence (weight) parameter giving the ratio of coherent to conventional quantum 1/f contributions.

  17. Quantum information transfer between topological and conventional charge qubits

    Science.gov (United States)

    Jun, Li; Yan, Zou

    2016-02-01

    We propose a scheme to realize coherent quantum information transfer between topological and conventional charge qubits. We first consider a hybrid system where a quantum dot (QD) is tunnel-coupled to a semiconductor Majorana-hosted nanowire (MNW) via using gated control as a switch, the information encoded in the superposition state of electron empty and occupied state can be transferred to each other through choosing the proper interaction time to make measurements. Then we consider another system including a double QDs and a pair of parallel MNWs, it is shown that the entanglement information transfer can be realized between the two kinds of systems. We also realize long distance quantum information transfer between two quantum dots separated by an MNW, by making use of the nonlocal fermionic level formed with the pared Majorana feimions (MFs) emerging at the two ends of the MNW. Furthermore, we analyze the teleportationlike electron transfer phenomenon predicted by Tewari et al. [Phys. Rev. Lett. 100, 027001 (2008)] in our considered system. Interestingly, we find that this phenomenon exactly corresponds to the case that the information encoded in one QD just returns back to its original place during the dynamical evolution of the combined system from the perspective of quantum state transfer. Project supported by the National Natural Science Foundation of China (Grant No. 11304031).

  18. On the photoelectric quantum yield of small dust particles

    Science.gov (United States)

    Kimura, Hiroshi

    2016-07-01

    Photoelectron emission is crucial to electric charging of dust particles around main-sequence stars and gas heating in various dusty environments. An estimate of the photoelectric processes contains an ill-defined parameter called the photoelectric quantum yield, which is the total number of electrons ejected from a dust particle per absorbed photon. Here we revisit the so-called small particle effect of photoelectron emission and provide an analytical model to estimate photoelectric quantum yields of small dust particles in sizes down to nanometers. We show that the small particle effect elevates the photoelectric quantum yields of nanoparticles up to by a factor of 103 for carbon, water ice, and organics, and a factor of 102 for silicate, silicon carbide, and iron. We conclude the surface curvature of the particles is a quantity of great importance to the small particle effect, unless the particles are submicrometers in radius or larger.

  19. On the photoelectric quantum yield of small dust particles

    CERN Document Server

    Kimura, Hiroshi

    2016-01-01

    Photoelectron emission is crucial to electric charging of dust particles around main-sequence stars and gas heating in various dusty environments. An estimate of the photoelectric processes contains an ill-defined parameter called the photoelectric quantum yield, which is the total number of electrons ejected from a dust particle per absorbed photon. Here we revisit the so-called small particle effect of photoelectron emission and provide an analytical model to estimate photoelectric quantum yields of small dust particles in sizes down to nanometers. We show that the small particle effect elevates the photoelectric quantum yields of nanoparticles up to by a factor of $10^3$ for carbon, water ice, and organics, and a factor of $10^2$ for silicate, silicon carbide, and iron. We conclude the surface curvature of the particles is a quantity of great importance to the small particle effect, unless the particles are submicrometers in radius or larger.

  20. Light propagation and fluorescence quantum yields in liquid scintillators

    Science.gov (United States)

    Buck, C.; Gramlich, B.; Wagner, S.

    2015-09-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  1. Light propagation and fluorescence quantum yields in liquid scintillators

    CERN Document Server

    Buck, C; Wagner, S

    2015-01-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  2. Low potato yields in Kenya: do conventional input innovations account for the yields disparity?

    NARCIS (Netherlands)

    M.P. van Dijk (Meine Pieter); J.G. Wang’ombe

    2013-01-01

    markdownabstract__Abstract__ Background: Potato yields in Kenya are less than half the amount obtained by some developed countries. Despite more acreage being dedicated to the crop, annual production has not improved. Kenya’s low yields have been blamed on a failure to use clean seeds, fertilizers,

  3. High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

    Science.gov (United States)

    Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-11-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.

  4. Photosynthetic Quantum Yield Dynamics: From Photosystems to Leaves

    NARCIS (Netherlands)

    Hogewoning, S.W.; Wientjes, E.; Douwstra, P.; Trouwborst, G.; Ieperen, van W.; Croce, R.; Harbinson, J.

    2012-01-01

    The mechanisms underlying the wavelength dependence of the quantum yield for CO2 fixation (a) and its acclimation to the growth-light spectrum are quantitatively addressed, combining in vivo physiological and in vitro molecular methods. Cucumber (Cucumis sativus) was grown under an artificial

  5. Photosynthetic Quantum Yield Dynamics : From Photosystems to Leaves

    NARCIS (Netherlands)

    Hogewoning, Sander W.; Wientjes, Emilie; Douwstra, Peter; Trouwborst, Govert; van Ieperen, Wim; Croce, Roberta; Harbinson, Jeremy

    The mechanisms underlying the wavelength dependence of the quantum yield for CO2 fixation (alpha) and its acclimation to the growth-light spectrum are quantitatively addressed, combining in vivo physiological and in vitro molecular methods. Cucumber (Cucumis sativus) was grown under an artificial

  6. Meteorological fluctuations define long-term crop yield patterns in conventional and organic production systems.

    Science.gov (United States)

    Teasdale, John R; Cavigelli, Michel A

    2017-04-06

    Variability in meteorological patterns presents significant challenges to crop production consistency and yield stability. Meteorological influences on corn and soybean grain yields were analyzed over an 18-year period at a long-term experiment in Beltsville, Maryland, U.S.A., comparing conventional and organic management systems. Precipitation and temperature variables explained much of the yield variability, with precipitation and heat stress during the late vegetative and early reproductive phases of crop growth accounting for the majority of yield variability in all crops and management systems. Crop yields under conventional and organic management followed similar periodic patterns, but yields were 31% and 20% lower in organic than conventional corn and soybean, respectively. The efficiency of grain yield per unit precipitation was higher under conventional than organic management, highlighting the importance of crop management for optimizing production in response to meteorological variability. Periodic yield and precipitation patterns did not consistently align with global meteorological cycles such as the El Niño Southern Oscillation.

  7. Potential Energy Surfaces and Quantum Yields for Photochromic Diarylethene Reactions

    Directory of Open Access Journals (Sweden)

    Makoto Hatakeyama

    2013-05-01

    Full Text Available Photochromic diarylethenes (DAEs are among the most promising molecular switching systems for future molecular electronics. Numerous derivatives have been synthesized recently, and experimental quantum yields (QYs have been reported for two categories of them. Although the QY is one of the most important properties in various applications, it is also the most difficult property to predict before a molecule is actually synthesized. We have previously reported preliminary theoretical studies on what determines the QYs in both categories of DAE derivatives. Here, reflecting theoretical analyses of potential energy surfaces and recent experimental results, a rational explanation of the general guiding principle for QY design is presented for future molecular design.

  8. Synthesis of Luminescent Graphene Quantum Dots with High Quantum Yield and Their Toxicity Study.

    Directory of Open Access Journals (Sweden)

    Dan Jiang

    Full Text Available High fluorescence quantum yield graphene quantum dots (GQDs have showed up as a new generation for bioimaging. In this work, luminescent GQDs were prepared by an ameliorative photo-Fenton reaction and a subsequent hydrothermal process using graphene oxide sheets as the precursor. The as-prepared GQDs were nanomaterials with size ranging from 2.3 to 6.4 nm and emitted intense green luminescence in water. The fluorescence quantum yield was as high as 24.6% (excited at 340 nm and the fluorescence was strongest at pH 7. Moreover, the influences of low-concentration (12.5, 25 μg/mL GQDs on the morphology, viability, membrane integrity, internal cellular reactive oxygen species level and mortality of HeLa cells were relatively weak, and the in vitro imaging demonstrated GQDs were mainly in the cytoplasm region. More strikingly, zebrafish embryos were co-cultured with GQDs for in vivo imaging, and the results of heart rate test showed the intake of small amounts of GQDs brought little harm to the cardiovascular of zebrafish. GQDs with high quantum yield and strong photoluminescence show good biocompatibility, thus they show good promising for cell imaging, biolabeling and other biomedical applications.

  9. Comparing milk yield, chemical properties and somatic cell count from organic and conventional mountain farming systems

    Directory of Open Access Journals (Sweden)

    Marcello Bianchi

    2010-01-01

    Full Text Available A study was undertaken to investigate the effects of farming systems (organic vs. conventional, diet (hay/concentrate vs. pasture and their interaction on milk yield, gross composition and fatty acid (FA profile of dairy cows bred in mountainous areas. For this purpose four dairy farms (two organic and two conventional were chosen in the alpine territory of Aosta Valley (NW Italy; individual milk yield was recorded daily and bulk milk samples were collected monthly from February to September 2007 to cover dietary variations. Higher levels of milk production (P<0.05 and lower milk protein amounts (P<0.01 were observed in the organic farms with respect to the conventional ones, while no significant differences were noticed in milk fat and lactose contents and in somatic cell count. Concerning fatty acids, only small differences were detected between organic and conventional milk and such differences seemed to be related mainly to the stabled period. Diet affected almost all variables studied: pasture feeding provided a significant improvement in the fatty acid composition in both organic and conventional systems leading to lower hypercholesterolemic saturated fatty acids, higher mono- and polyunsaturated fatty acids and conjugated linoleic acid amounts (P<0.001.

  10. Film quantum yields of EUV& ultra-high PAG photoresists

    Energy Technology Data Exchange (ETDEWEB)

    Hassanein, Elsayed; Higgins, Craig; Naulleau, Patrick; Matyi, Richard; Gallatin, Greg; Denbeaux, Gregory; Antohe, Alin; Thackery, Jim; Spear, Kathleen; Szmanda, Charles; Anderson, Christopher N.; Niakoula, Dimitra; Malloy, Matthew; Khurshid, Anwar; Montgomery, Cecilia; Piscani, Emil C.; Rudack, Andrew; Byers, Jeff; Ma, Andy; Dean, Kim; Brainard, Robert

    2008-01-10

    Base titration methods are used to determine C-parameters for three industrial EUV photoresist platforms (EUV-2D, MET-2D, XP5496) and twenty academic EUV photoresist platforms. X-ray reflectometry is used to measure the density of these resists, and leads to the determination of absorbance and film quantum yields (FQY). Ultrahigh levels ofPAG show divergent mechanisms for production of photo acids beyond PAG concentrations of 0.35 moles/liter. The FQY of sulfonium PAGs level off, whereas resists prepared with iodonium PAG show FQY s that increase beyond PAG concentrations of 0.35 moles/liter, reaching record highs of 8-13 acids generatedlEUV photons absorbed.

  11. Durum Wheat in Conventional and Organic Farming: Yield Amount and Pasta Quality in Southern Italy

    Directory of Open Access Journals (Sweden)

    Massimo Fagnano

    2012-01-01

    Full Text Available Five durum wheat cultivars were grown in a Mediterranean area (Southern Italy under conventional and organic farming with the aim to evaluate agronomic, technological, sensory, and sanitary quality of grains and pasta. The cultivar Matt produced the best pasta quality under conventional cropping system, while the quality parameters evaluated were unsatisfactory under organic farming. The cultivar Saragolla showed the best yield amount and pasta quality in all the experimental conditions, thus proving to be the cultivar more adapt to organic farming. In all the tested experimental conditions, nivalenol (NIV and deoxynivalenol (DON occurrence was very low and the other mycotoxins evaluated were completely absent. These data confirm the low risk of mycotoxin contamination in the Mediterranean climate conditions. Finally, it has been possible to produce high-quality pasta in Southern Italy from durum wheat grown both in conventional and organic farming.

  12. Durum wheat in conventional and organic farming: yield amount and pasta quality in Southern Italy.

    Science.gov (United States)

    Fagnano, Massimo; Fiorentino, Nunzio; D'Egidio, Maria Grazia; Quaranta, Fabrizio; Ritieni, Alberto; Ferracane, Rosalia; Raimondi, Giampaolo

    2012-01-01

    Five durum wheat cultivars were grown in a Mediterranean area (Southern Italy) under conventional and organic farming with the aim to evaluate agronomic, technological, sensory, and sanitary quality of grains and pasta. The cultivar Matt produced the best pasta quality under conventional cropping system, while the quality parameters evaluated were unsatisfactory under organic farming. The cultivar Saragolla showed the best yield amount and pasta quality in all the experimental conditions, thus proving to be the cultivar more adapt to organic farming. In all the tested experimental conditions, nivalenol (NIV) and deoxynivalenol (DON) occurrence was very low and the other mycotoxins evaluated were completely absent. These data confirm the low risk of mycotoxin contamination in the Mediterranean climate conditions. Finally, it has been possible to produce high-quality pasta in Southern Italy from durum wheat grown both in conventional and organic farming.

  13. Quantum Theory From a Non-Conventional Perspective

    Science.gov (United States)

    Schuch, D.

    2017-05-01

    Quantum mechanics is essentially described in terms of complex quantities like wave functions. The interesting point is that phase and amplitude of the complex quantities are not independent of each other, but coupled by some kind of conservation law. This coupling exists in time-independent quantum mechanics as well as in in its time-dependent form. It can be traced back to a reformulation of quantum mechanics in terms of complex nonlinear Riccati equations, where the quadratic term in the latter equation explains the origin of the phase-amplitude coupling. Since realistic physical systems are always in contact with some kind of environment this aspect is also taken into account. It turns out that this dissipative effect can either affect the amplitude or the phase of the complex quantity describing the open quantum system. This suggests a relation between non-unitary transformations and gauge-transformations for these systems. A change of the amplitude also seems to be connected with a second quantum of action for “radial” changes, compared to ħ for “angular” changes, leading to an interpretation of Sommerfeld’s constant.

  14. Size effects in the quantum yield of Cd Te quantum dots for optimum fluorescence bioimaging

    Energy Technology Data Exchange (ETDEWEB)

    Jacinto, C.; Rocha, U.S. [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil). Inst. de Fisica. Grupo de Fotonica e Fluidos Complexos; Maestro, L.M.; Garcia-Sole, J.; Jaque, D. [Universidad Autonoma de Madrid (Spain). Dept. de Fisica de Materiales. Fluorescence Imaging Group

    2011-07-01

    those achievable when using CdSe-QDs. In this work, the size dependence of the fluorescence quantum yield of CdTe Quantum dots has been systematically investigated by Thermal Lens Spectroscopy. It has been found that optimum quantum yield is reached for 3.7 nm quantum dots. The presence of this optimum size has been corroborated by fluorescence experiments. Combination of quantum yield and fluorescence decay time measurements have concluded that the appearance of this optimum size emerges from the interplay between the frequency dependent radiative emission rate and the size dependent coupling strength between bulk exciton and surface trapping states. Our results open a new avenue in the search for new fluorescent 'multifunctional nanoprobes' for high resolution fluorescence imaging at the nanoscale. (author)

  15. Comparison between genomic predictions using daughter yield deviation and conventional estimated breeding value as response variables

    DEFF Research Database (Denmark)

    Guo, Gang; Lund, Mogens Sandø; Zhang, Y;

    2010-01-01

    This study compared genomic predictions using conventional estimated breeding values (EBV) and daughter yield deviations (DYD) as response variables based on simulated data. Eight scenarios were simulated in regard to heritability (0.05 and 0.30), number of daughters per sire (30, 100, and unequal......), the EBV and DYD approaches provided similar genomic estimated breeding value (GEBV) reliabilities, except for scenarios with unequal numbers of daughters and half of sires without genotype, for which the EBV approach was superior to the DYD approach (by 1.2 and 2.4%). Using a Bayesian mixture prior model...

  16. Near-unity photoluminescence quantum yield in MoS₂.

    Science.gov (United States)

    Amani, Matin; Lien, Der-Hsien; Kiriya, Daisuke; Xiao, Jun; Azcatl, Angelica; Noh, Jiyoung; Madhvapathy, Surabhi R; Addou, Rafik; KC, Santosh; Dubey, Madan; Cho, Kyeongjae; Wallace, Robert M; Lee, Si-Chen; He, Jr-Hau; Ager, Joel W; Zhang, Xiang; Yablonovitch, Eli; Javey, Ali

    2015-11-27

    Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure of merit, the room-temperature photoluminescence quantum yield (QY), is extremely low. The prototypical 2D material molybdenum disulfide (MoS2) is reported to have a maximum QY of 0.6%, which indicates a considerable defect density. Here we report on an air-stable, solution-based chemical treatment by an organic superacid, which uniformly enhances the photoluminescence and minority carrier lifetime of MoS2 monolayers by more than two orders of magnitude. The treatment eliminates defect-mediated nonradiative recombination, thus resulting in a final QY of more than 95%, with a longest-observed lifetime of 10.8 ± 0.6 nanoseconds. Our ability to obtain optoelectronic monolayers with near-perfect properties opens the door for the development of highly efficient light-emitting diodes, lasers, and solar cells based on 2D materials.

  17. Quantum dot/plasmonic nanoparticle metachromophores with quantum yields that vary with excitation wavelength.

    Science.gov (United States)

    Munechika, Keiko; Chen, Yeechi; Tillack, Andreas F; Kulkarni, Abhishek P; Jen-La Plante, Ilan; Munro, Andrea M; Ginger, David S

    2011-07-13

    Coupled plasmonic/chromophore systems are of interest in applications ranging from fluorescent biosensors to solar photovoltaics and photoelectrochemical cells because near-field coupling to metal nanostructures can dramatically alter the optical performance of nearby materials. We show that CdSe quantum dots (QDs) near single silver nanoprisms can exhibit photoluminescence lifetimes and quantum yields that depend on the excitation wavelength, in apparent violation of the Kasha-Vavilov rule. We attribute the variation in QD lifetime with excitation wavelength to the wavelength-dependent coupling of higher-order plasmon modes to different spatial subpopulations of nearby QDs. At the QD emission wavelength, these subpopulations are coupled to far-field radiation with varying efficiency by the nanoprism dipolar resonance. These results offer an easily accessible new route to design metachromophores with tailored optical properties.

  18. Near-unity quantum yields from chloride treated CdTe colloidal quantum dots.

    Science.gov (United States)

    Page, Robert C; Espinobarro-Velazquez, Daniel; Leontiadou, Marina A; Smith, Charles; Lewis, Edward A; Haigh, Sarah J; Li, Chen; Radtke, Hanna; Pengpad, Atip; Bondino, Federica; Magnano, Elena; Pis, Igor; Flavell, Wendy R; O'Brien, Paul; Binks, David J

    2015-04-01

    Colloidal quantum dots (CQDs) are promising materials for novel light sources and solar energy conversion. However, trap states associated with the CQD surface can produce non-radiative charge recombination that significantly reduces device performance. Here a facile post-synthetic treatment of CdTe CQDs is demonstrated that uses chloride ions to achieve near-complete suppression of surface trapping, resulting in an increase of photoluminescence (PL) quantum yield (QY) from ca. 5% to up to 97.2 ± 2.5%. The effect of the treatment is characterised by absorption and PL spectroscopy, PL decay, scanning transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. This process also dramatically improves the air-stability of the CQDs: before treatment the PL is largely quenched after 1 hour of air-exposure, whilst the treated samples showed a PL QY of nearly 50% after more than 12 hours.

  19. High Quantum Yield Blue Emission from Lead-Free Inorganic Antimony Halide Perovskite Colloidal Quantum Dots.

    Science.gov (United States)

    Zhang, Jian; Yang, Ying; Deng, Hui; Farooq, Umar; Yang, Xiaokun; Khan, Jahangeer; Tang, Jiang; Song, Haisheng

    2017-09-26

    Colloidal quantum dots (QDs) of lead halide perovskite have recently received great attention owing to their remarkable performances in optoelectronic applications. However, their wide applications are hindered from toxic lead element, which is not environment- and consumer-friendly. Herein, we utilized heterovalent substitution of divalent lead (Pb(2+)) with trivalent antimony (Sb(3+)) to synthesize stable and brightly luminescent Cs3Sb2Br9 QDs. The lead-free, full-inorganic QDs were fabricated by a modified ligand-assisted reprecipitation strategy. A photoluminescence quantum yield (PLQY) was determined to be 46% at 410 nm, which was superior to that of other reported halide perovskite QDs. The PL enhancement mechanism was unraveled by surface composition derived quantum-well band structure and their large exciton binding energy. The Br-rich surface and the observed 530 meV exciton binding energy were proposed to guarantee the efficient radiative recombination. In addition, we can also tune the inorganic perovskite QD (Cs3Sb2X9) emission wavelength from 370 to 560 nm via anion exchange reactions. The developed full-inorganic lead-free Sb-perovskite QDs with high PLQY and stable emission promise great potential for efficient emission candidates.

  20. Fluorescence quantum yield of thioflavin T in rigid isotropic solution and incorporated into the amyloid fibrils.

    Directory of Open Access Journals (Sweden)

    Anna I Sulatskaya

    Full Text Available In this work, the fluorescence of thioflavin T (ThT was studied in a wide range of viscosity and temperature. It was shown that ThT fluorescence quantum yield varies from 0.0001 in water at room temperature to 0.28 in rigid isotropic solution (T/η→0. The deviation of the fluorescence quantum yield from unity in rigid isotropic solution suggests that fluorescence quantum yield depends not only on the ultra-fast oscillation of ThT fragments relative to each other in an excited state as was suggested earlier, but also depends on the molecular configuration in the ground state. This means that the fluorescence quantum yield of the dye incorporated into amyloid fibrils must depend on its conformation, which, in turn, depends on the ThT environment. Therefore, the fluorescence quantum yield of ThT incorporated into amyloid fibrils can differ from that in the rigid isotropic solution. In particular, the fluorescence quantum yield of ThT incorporated into insulin fibrils was determined to be 0.43. Consequently, the ThT fluorescence quantum yield could be used to characterize the peculiarities of the fibrillar structure, which opens some new possibilities in the ThT use for structural characterization of the amyloid fibrils.

  1. Vertical farming increases lettuce yield per unit area compared to conventional horizontal hydroponics.

    Science.gov (United States)

    Touliatos, Dionysios; Dodd, Ian C; McAinsh, Martin

    2016-08-01

    Vertical farming systems (VFS) have been proposed as an engineering solution to increase productivity per unit area of cultivated land by extending crop production into the vertical dimension. To test whether this approach presents a viable alternative to horizontal crop production systems, a VFS (where plants were grown in upright cylindrical columns) was compared against a conventional horizontal hydroponic system (HHS) using lettuce (Lactuca sativa L. cv. "Little Gem") as a model crop. Both systems had similar root zone volume and planting density. Half-strength Hoagland's solution was applied to plants grown in perlite in an indoor controlled environment room, with metal halide lamps providing artificial lighting. Light distribution (photosynthetic photon flux density, PPFD) and yield (shoot fresh weight) within each system were assessed. Although PPFD and shoot fresh weight decreased significantly in the VFS from top to base, the VFS produced more crop per unit of growing floor area when compared with the HHS. Our results clearly demonstrate that VFS presents an attractive alternative to horizontal hydroponic growth systems and suggest that further increases in yield could be achieved by incorporating artificial lighting in the VFS.

  2. High quantum yield graphene quantum dots decorated TiO2 nanotubes for enhancing photocatalytic activity

    Science.gov (United States)

    Qu, Ailan; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

    2016-07-01

    Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO2 nanotubes (GQDs/TiO2 NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600-800 nm. The photocatalytic activity of prepared GQDs/TiO2 NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO2 nanotubes (TiO2 NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV-vis light irradiation (λ = 380-780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO2 NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO2 NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO2 composite.

  3. Gradient CdSe/CdS Quantum Dots with Room Temperature Biexciton Unity Quantum Yield.

    Science.gov (United States)

    Nasilowski, Michel; Spinicelli, Piernicola; Patriarche, Gilles; Dubertret, Benoît

    2015-06-10

    Auger recombination is a major limitation for the fluorescent emission of quantum dots (QDs). It is the main source of QDs fluorescence blinking at the single-particle level. At high-power excitation, when several charge carriers are formed inside a QD, Auger becomes more efficient and severely decreases the quantum yield (QY) of multiexcitons. This limits the efficiency and the use of colloidal QDs in applications where intense light output is required. Here, we present a new generation of thick-shell CdSe/CdS QDs with dimensions >40 nm and a composition gradient between the core and the shell that exhibits 100% QY for the emission of both the monoexciton and the biexciton in air and at room temperature for all the QDs we have observed. The fluorescence emission of these QDs is perfectly Poissonian at the single-particle level at different excitation levels and temperatures, from 30 to 300 K. In these QDs, the emission of high-order (>2) multiexcitons is quite efficient, and we observe white light emission at the single-QD level when high excitation power is used. These gradient thick shell QDs confirm the suppression of Auger recombination in gradient core/shell structures and help further establish the colloidal QDs with a gradient shell as a very stable source of light even under high excitation.

  4. Controlled fabrication of individual silicon quantum rods yielding high intensity, polarized light emission

    Science.gov (United States)

    Bruhn, Benjamin; Valenta, Jan; Linnros, Jan

    2009-12-01

    Elongated silicon quantum dots (also referred to as rods) were fabricated using a lithographic process which reliably yields sufficient numbers of emitters. These quantum rods are perfectly aligned and the vast majority are spatially separated well enough to enable single-dot spectroscopy. Not only do they exhibit extraordinarily high linear polarization with respect to both absorption and emission, but the silicon rods also appear to luminesce much more brightly than their spherical counterparts. Significantly increased quantum efficiency and almost unity degree of linear polarization render these quantum rods perfect candidates for numerous applications.

  5. Innovations in papermaking: an LCA of printing and writing paper from conventional and high yield pulp.

    Science.gov (United States)

    Manda, B M Krishna; Blok, Kornelis; Patel, Martin K

    2012-11-15

    Pulp and paper industry is facing challenges such as resource scarcity and greenhouse gas (GHG) emissions. The objective of this research is to investigate whether the use of new coatings (micro or nano TiO(2)) and different pulp types could bring savings in wood, energy, GHG emissions and other environmental impacts in comparison with conventional printing and writing paper. We studied three types of pulp, namely i) unbleached virgin kraft pulp, ii) recovered fiber, and iii) high yield virgin chemithermo-mechanical pulp (CTMP). A life cycle assessment (LCA) was conducted from cradle to grave. Applying attributional modeling, we found that wood savings amount to 60% for the nanoparticle coated recovered fiber paper and 35% for the micro TiO(2) coated CTMP paper. According to the ReCiPe single score impact assessment method, the new product configurations allow the reduction of the environmental impacts by 10-35% compared to conventional kraft paper. Applying consequential modeling, we found larger energy and GHG emission savings compared to attributional modeling because the saved wood is used for producing energy, thereby replacing fossil fuels. The nanoparticle coated recovered fiber paper offered savings of non-renewable energy use (NREU) by 100% (13GJ/ton paper) and GHG emission reduction by 75% (0.6 tonCO(2)eq./ton paper). Micro TiO(2) coated CTMP paper offered NREU savings by 25% (3GJ/ton paper) and savings of GHG emissions by 10% (0.1 tonCO(2)eq./ton paper). The taking into account of all environmental impacts with the ReCiPe single score method leads to comparable results as that of attributional modeling. We conclude that the nanoparticle coated recovered fiber paper offered the highest savings and lowest environmental impacts. However, human toxicity and ecotoxicity impacts of the nanoparticles were not included in this analysis and need further research. If this leads to the conclusion that the toxicity impacts of the nanoparticles are serious, then the

  6. Innovations in papermaking: An LCA of printing and writing paper from conventional and high yield pulp

    Energy Technology Data Exchange (ETDEWEB)

    Manda, B.M. Krishna, E-mail: b.m.k.manda@uu.nl; Blok, Kornelis, E-mail: K.Blok@uu.nl; Patel, Martin K., E-mail: m.k.patel@uu.nl

    2012-11-15

    Pulp and paper industry is facing challenges such as resource scarcity and greenhouse gas (GHG) emissions. The objective of this research is to investigate whether the use of new coatings (micro or nano TiO{sub 2}) and different pulp types could bring savings in wood, energy, GHG emissions and other environmental impacts in comparison with conventional printing and writing paper. We studied three types of pulp, namely i) unbleached virgin kraft pulp, ii) recovered fiber, and iii) high yield virgin chemithermo-mechanical pulp (CTMP). A life cycle assessment (LCA) was conducted from cradle to grave. Applying attributional modeling, we found that wood savings amount to 60% for the nanoparticle coated recovered fiber paper and 35% for the micro TiO{sub 2} coated CTMP paper. According to the ReCiPe single score impact assessment method, the new product configurations allow the reduction of the environmental impacts by 10-35% compared to conventional kraft paper. Applying consequential modeling, we found larger energy and GHG emission savings compared to attributional modeling because the saved wood is used for producing energy, thereby replacing fossil fuels. The nanoparticle coated recovered fiber paper offered savings of non-renewable energy use (NREU) by 100% (13 GJ/ton paper) and GHG emission reduction by 75% (0.6 ton CO{sub 2} eq./ton paper). Micro TiO{sub 2} coated CTMP paper offered NREU savings by 25% (3 GJ/ton paper) and savings of GHG emissions by 10% (0.1 ton CO{sub 2} eq./ton paper). The taking into account of all environmental impacts with the ReCiPe single score method leads to comparable results as that of attributional modeling. We conclude that the nanoparticle coated recovered fiber paper offered the highest savings and lowest environmental impacts. However, human toxicity and ecotoxicity impacts of the nanoparticles were not included in this analysis and need further research. If this leads to the conclusion that the toxicity impacts of the

  7. Air-insufflated high-definition dacryoendoscopy yields significantly better image quality than conventional dacryoendoscopy.

    Science.gov (United States)

    Sasaki, Tsugihisa; Sounou, Tsutomu; Tsuji, Hideki; Sugiyama, Kazuhisa

    2017-01-01

    To facilitate the analysis of lacrimal conditions, we utilized high-definition dacryoendoscopy (HDD) and undertook observations with a pressure-controlled air-insufflation system. We report the safety and performance of HDD. In this retrospective, non-randomized clinical trial, 46 patients (14 males and 32 females; age range 39-91 years; mean age ± SD 70.3±12.0 years) who had lacrimal disorders were examined with HDD and conventional dacryoendoscopy (CD). The high-definition dacryoendoscope had 15,000 picture element image fibers and an advanced objective lens. Its outer diameter was 0.9-1.2 mm. Air insufflation was controlled at 0-20 kPa with a digital manometer-based pressure-controlled air-insufflation system to evaluate the quality of the image. The HDD had an air/saline irrigation channel between the outer sheath (outer diameter =1.2 mm) and the metal inner sheath of the endoscope. We used it and the CD in air, saline, and diluted milk saline with and without manual irrigation to quantitatively evaluate the effect of air pressure and saline irrigation on image quality. In vivo, the most significant improvement in image quality was demonstrated with air-insufflated (5-15 kPa) HDD, as compared with saline-irrigated HDD and saline-irrigated CD. No emphysema or damage was noted under observation with HDD. In vitro, no significant difference was demonstrated between air-insufflated HDD and saline-irrigated HDD. In vitro, the image quality of air-insufflated HDD was significantly improved as compared with that of saline-irrigated CD. Pressure-controlled (5-15 kPa) air-insufflated HDD is safe, and yields significantly better image quality than CD and saline-irrigated HDD.

  8. Can we Predict Quantum Yields Using Excited State Density Functional Theory for New Families of Fluorescent Dyes?

    Science.gov (United States)

    Kohn, Alexander W.; Lin, Zhou; Shepherd, James J.; Van Voorhis, Troy

    2016-06-01

    For a fluorescent dye, the quantum yield characterizes the efficiency of energy transfer from the absorbed light to the emitted fluorescence. In the screening among potential families of dyes, those with higher quantum yields are expected to have more advantages. From the perspective of theoreticians, an efficient prediction of the quantum yield using a universal excited state electronic structure theory is in demand but still challenging. The most representative examples for such excited state theory include time-dependent density functional theory (TDDFT) and restricted open-shell Kohn-Sham (ROKS). In the present study, we explore the possibility of predicting the quantum yields for conventional and new families of organic dyes using a combination of TDDFT and ROKS. We focus on radiative (kr) and nonradiative (knr) rates for the decay of the first singlet excited state (S_1) into the ground state (S_0) in accordance with Kasha's rule. M. Kasha, Discuss. Faraday Soc., 9, 14 (1950). For each dye compound, kr is calculated with the S_1-S_0 energy gap and transition dipole moment obtained using ROKS and TDDFT respectively at the relaxed S_1 geometry. Our predicted kr agrees well with the experimental value, so long as the order of energy levels is correctly predicted. Evaluation of knr is less straightforward as multiple processes are involved. Our study focuses on the S_1-T_1 intersystem crossing (ISC) and the S_1-S_0 internal conversion (IC): we investigate the properties that allow us to model the knr value using a Marcus-like expression, such as the Stokes shift, the reorganization energy, and the S_1-T_1 and S_1-S_0 energy gaps. Taking these factors into consideration, we compare our results with those obtained using the actual Marcus theory and provide explanation for discrepancy. T. Kowalczyk, T. Tsuchimochi, L. Top, P.-T. Chen, and T. Van Voorhis, J. Chem. Phys., 138, 164101 (2013). M. Kasha, Discuss. Faraday Soc., 9, 14 (1950).

  9. Phosphorescence quantum yield determination with time-gated fluorimeter and Tb(III)-acetylacetonate as luminescence reference

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultät für Physik, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg (Germany)

    2013-03-29

    Highlights: ► Procedure for absolute phosphorescence quantum yield measurement is described. ► Experimental setup for absolute luminescence quantum yield standard calibration. ► Tb(acac){sub 3} proposed as phosphorescence quantum yield reference standard. ► Luminescence quantum yield of Tb(acac){sub 3} in cyclohexane measured. ► Luminescence lifetime of Tb(acac){sub 3} in cyclohexane measured. - Abstract: Phosphorescence quantum yield measurements of fluorescent and phosphorescent samples require the use of time-gated fluorimeters in order to discriminate against the fluorescence contribution. As reference standard a non-fluorescent luminescent compound is needed for absolute phosphorescence quantum yield determination. For this purpose the luminescence behavior of the rare earth chelate terbium(III)-acetylacetonate (Tb(acac){sub 3}) was studied (determination of luminescence quantum yield and luminescence lifetime). The luminescence quantum yield of Tb(acac){sub 3} was determined by using an external light source and operating the fluorimeter in chemo/bioluminescence mode with a fluorescent dye (rhodamine 6G in methanol) as reference standard. A procedure is developed for absolute luminescence (phosphorescence) quantum yield determination of samples under investigation with a time-gated fluorimeter using a non-fluorescent luminescent compound of known luminescence quantum yield and luminescence lifetime.

  10. Preparation of carbon quantum dots with a high quantum yield and the application in labeling bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Pengpeng; Zhang, Changchang; Liu, Xiang, E-mail: liuxiang@ahut.edu.cn; Cui, Ping, E-mail: cokecp@sohu.com

    2016-04-15

    Graphical abstract: - Highlights: • Cheap carbon quantum dots (CQDs) with a high quantum yield were prepared. • The preparation process and surface functionalization on CQDs are rather facile. • Such functionalized CQDs can be attached to BSA covalently. • This predicts that some biomolecules can be labeled by the fluorescent CQDs. - Abstract: An economic and green approach of manufacturing carbon quantum dots (CQDs) with a high quantum yield (denoted with HQY-CQDs) and the application in labeling bovine serum albumin (BSA) were described in detail in this work. Firstly, the cheap resources of citric acid and glycine were pyrolysed in drying oven for preparing the CQDs. Then the product was immersed in tetrahydrofuran for 8 h. HQY-CQDs were obtained by removing tetrahydrofuran from the supernate and were evaluated that they possessed a much higher quantum yield compared with that without dealing with tetrahydrofuran and a wonderful photo-bleaching resistance. Such HQY-CQDs could be functionalized by N-hydroxysuccinimide and successively combined with BSA covalently. Thus fluorescent labeling on BSA was realized. The HQY-CQDs were demonstrated with transmission electron microscopy and the chemical modification with N-hydroxysuccinimide was proved by infrared and X-ray photoelectron spectra. Labeling BSA with the HQY-CQDs was confirmed by gel electrophoresis and fluorescence imaging.

  11. Morphological effects in the quantum yield of cesium iodide

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, J. [Ecole Politechnique Federale, Lausanne (Switzerland). DP-IPA PH-Ecublens; Barbo, F. [Sincrotrone Trieste SpA, Padriciano 99, 34012 Trieste (Italy); Bertolo, M. [Sincrotrone Trieste SpA, Padriciano 99, 34012 Trieste (Italy); Bianco, A. [Sincrotrone Trieste SpA, Padriciano 99, 34012 Trieste (Italy); Braem, A. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments; Cerasari, S. [Sincrotrone Trieste SpA, Padriciano 99, 34012 Trieste (Italy); Coluzza, C. [Ecole Politechnique Federale, Lausanne (Switzerland). DP-IPA PH-Ecublens; Dell`Orto, T. [Ecole Politechnique Federale, Lausanne (Switzerland). DP-IPA PH-Ecublens; Fontana, S. [Sincrotrone Trieste SpA, Padriciano 99, 34012 Trieste (Italy); Margaritondo, G. [Ecole Politechnique Federale, Lausanne (Switzerland). DP-IPA PH-Ecublens; Nappi, E. [Istituto Nazionale di Fisica Nucleare, Bari (Italy); Paic, G. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments; Piuz, F. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments; Sanjines, R. [Ecole Politechnique Federale, Lausanne (Switzerland). DP-IPA PH-Ecublens; Scognetti, T. [Istituto Nazionale di Fisica Nucleare, Bari (Italy); Sgobba, S. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments

    1995-07-15

    We demonstrated that polycrystalline cesium iodide (CsI) on large area Ni/Au coated printed board provides a quantum efficiency (QE) higher by a factor of 2 than the films deposited on the standard Cu/Au printed circuits. This is the most important result of the present systematic study of the QE lateral inhomogeneity for CsI on different substrates. We found a strong correlation between the QE lateral variation and the morphological homogeneity of the films. The QE was measured by UV photoelectron emission microscopy and spatially resolved X-ray photoemission, and the morphology studies were performed by secondary electron microscopy, X-ray diffraction and scanning tunneling microscopy. (orig.).

  12. A meta-analysis of maize and wheat yields in low-input vs. conventional and organic systems

    Science.gov (United States)

    Organic and low-input systems are proposed as ways to reduce the environmental impacts of agriculture. Previous studies have shown that yields of organic systems can be ~19-25% lower than conventional systems. An intermediary, low-input system could be less damaging for the environment than conventi...

  13. Quantum Yield Measurements of Fluorophores in Lipid Bilayers Using a Plasmonic Nanocavity.

    Science.gov (United States)

    Schneider, Falk; Ruhlandt, Daja; Gregor, Ingo; Enderlein, Jörg; Chizhik, Alexey I

    2017-03-20

    Precise knowledge of the quantum yield is important for many fluorescence-spectroscopic techniques, for example, for Förster resonance energy transfer. However, to measure it for emitters in a complex environment and at low concentrations is far from being trivial. Using a plasmonic nanocavity, we measure the absolute quantum yield value of lipid-conjugated dyes incorporated into a supported lipid bilayer. We show that for both hydrophobic and hydrophilic molecules the quantum yield of dyes inside the lipid bilayer strongly differs from its value in aqueous solution. This finding is of particular importance for all fluorescence-spectroscopic studies involving lipid bilayers, such as protein-protein or protein-lipid interactions in membranes or direct fluorescence-spectroscopic measurements of membrane physical properties.

  14. Cereal yield and quality as affected by N availability in organic and conventional crop rotations in Denmark

    DEFF Research Database (Denmark)

    Doltra, Jordi; Lægdsmand, Mette; Olesen, Jørgen E

    2011-01-01

    The effects of nitrogen (N) availability related to fertilizer type, catch crop management, and rotation composition on cereal yield and grain N were investigated in four organic and one conventional cropping systems in Denmark using the FASSET model. The four-year rotation studied was: spring......-clover were removed from the plots and an equivalent amount of total-N in pig slurry was applied to the cropping system. The conventional rotation included mineral fertilizer and catch crops (CF + C + F), although only non-legume catch crops were used. Measurements of cereal dry matter (DM) at harvest...... loamy soil. DM yield and grain N content were mainly influenced by the type and amount of fertilizer-N at all three locations. Although a catch crop benefit in terms of yield and grain N was observed in most of the cases, a limited N availability affected the cereal production in the four organic...

  15. Quantum yield of photosynthesis in the Baltic: a new mathematical expression for remote sensing applications

    Directory of Open Access Journals (Sweden)

    Bogdan Woźniak

    2007-12-01

    Full Text Available Statistical relationships between the quantum yield of photosynthesis Φ and selected environmental factors in the Baltic have been established on the basis of a large quantity of empirical data. The model formula is the product of the theoreticalmaximum quantum yield ΦMAX = 0.125 atomC quantum-1 and five dimensionless factors fi taking values from 0 do 1:Φ = ΦMAX fa fΔ fc(Ca(0 fc(PARinh fE,t.To a sufficiently good approximation, each of these factors fi appears to be dependent on one or at most two environmental factors, such as temperature, underwater irradiance, surface concentration of chlorophyll a, absorption properties of phytoplankton and optical depth. These dependences have been determined for Baltic Case 2 waters. The quantum yield Φ, calculated from known values of these environmental factors, is then applicable in the model algorithmfor the remote sensing of Baltic primary production. The statistical error of the approximate quantum yields Φ is 62%.

  16. GROWTH, PHYSIOLOGY AND YIELD OF FORMOSA ‘PAPAYA’ CULTIVATED UNDER DIFFERENT DOSES OF COATED AND CONVENTIONAL UREA

    Directory of Open Access Journals (Sweden)

    GABRIEL BARBOSA DA SILVA JÚNIOR

    2016-01-01

    Full Text Available Mineral fertilizer management is one of the most important agronomic techniques applied in papaya cultivation, which generally extracts large amounts of nutrients from soil, especially nitrogen. This study aimed to assess the phytotechnical and physiological attributes and yield of „Formosa‟ papaya hybrid Caliman 01 as a function of different doses of coated and conventional urea in the region of Bom Jesus - PI, Brazil. The treatments were arranged in a factorial scheme (2 × 4 and distributed in a randomized block design with four replications, corresponding to 2 nitrogen sources (coated urea, 43% of N; and conventional urea, 45% of N and 4 doses nitrogen (350, 440, 530 and 620 g per plant. The N doses used corresponded to 80, 100, 120 and 140% of the nitrogen fertilization. It was used six plants per plot with two row borders, totaling 192 plants cultivated in the field. It was assessed the intercepted photosynthetically active radiation (int.PAR, radiation interception efficiency (PAREff., leaf area index (LAI, plant height, stem diameter and yield. The coated urea promotes a higher growth and yield of „Formosa‟ papaya compared to the conventional urea. The application of 1.0 g of coated N promotes the production of 2.87 g of fruit per hectare while the application of 1.0 g of conventional N produces only 1.89 g of fruit per hectare, showing that the source of polymerized N increases the use efficiency of N applied to soil.

  17. Productivity, Profitability and Resource Use Efficiency: A Comparative Analysis between Conventional and High Yielding Rice in Rajbari District, Bangladesh

    Directory of Open Access Journals (Sweden)

    Md. Yahia Bapari

    2016-10-01

    Full Text Available The study was analyzed the determinants, costs and benefits and resources allocation of both conventional and high yielding rice cultivation over the Rajbari district of Bangladesh. Data were accumulated from 300 regular rice growers of conventional and high yielding varieties and random sampling technique was applied for selecting the respondents from the study area from which information was collected through pre-tested questionnaire. Cobb – Douglas production function and gross margin were mainly used to determine the productivities and profits of both rice and the marginal value of the product was highly recommended to derive the optimal use of the resources. Results obtained by applying ordinary least square method showed that the most important factors of production in the study area were irrigation, labor, fertilizer and insecticide costs whose elasticities were 0.904, 0.048, 0.045 and 0.044 respectively and insignificant factors were seed and ploughing costs whose elasticities were – 0.009 and 0.030 respectively for high yielding rice. On the other hand, irrigation, insecticide, seed and ploughing costs of elasticities 0.880, 0.589, 0.116 and – 0.127 respectively were the important factors and minor role playing factors were labor and fertilizer costs whose elasticities were 0.098 and 0.077 respectively for conventional yielding rice. The core message from productivity analysis was that the irrigation was key variable which played a positive and vital role in producing rice of both varieties. All variables (resources were economically misallocated in the production activities of both varieties along the study area but high yielding rice was more profitable than conventional one. Results also showed that the farmers of the study area produced rice of both varieties in the inefficient range of production. Continuous supply of electricity, flexible credit and improving the existing resources were the prime policy recommendations of

  18. Control of the external photoluminescent quantum yield of emitters coupled to nanoantenna phased arrays

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ke; Verschuuren, Marc A. [Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); Lozano, Gabriel [Center for Nanophotonics, FOM Institute AMOLF, c/o Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); Gómez Rivas, Jaime, E-mail: J.Gomez@amolf.nl [Center for Nanophotonics, FOM Institute AMOLF, c/o Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2015-08-21

    Optical losses in metals represent the largest limitation to the external quantum yield of emitters coupled to plasmonic antennas. These losses can be at the emission wavelength, but they can be more important at shorter wavelengths, i.e., at the excitation wavelength of the emitters, where the conductivity of metals is usually lower. We present accurate measurements of the absolute external photoluminescent quantum yield of a thin layer of emitting material deposited over a periodic nanoantenna phased array. Emission and absorptance measurements of the sample are performed using a custom-made setup including an integrating sphere and variable angle excitation. The measurements reveal a strong dependence of the external quantum yield on the angle at which the optical field excites the sample. Such behavior is attributed to the coupling between far-field illumination and near-field excitation mediated by the collective resonances supported by the array. Numerical simulations confirm that the inherent losses associated with the metal can be greatly reduced by selecting an optimum angle of illumination, which boosts the light conversion efficiency in the emitting layer. This combined experimental and numerical characterization of the emission from plasmonic arrays reveals the need to carefully design the illumination to achieve the maximum external quantum yield.

  19. Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

    NARCIS (Netherlands)

    Flameling, I.A.; Kromkamp, J.C.

    1998-01-01

    Quantum yields of photosystem II (PSII) charge separation (Phi(P)) and oxygen production (Phi(O2)) were determined by simultaneous measurements of oxygen production and variable fluorescence in four different aquatic microalgae representing three different taxonomic groups: the freshwater alga

  20. Variations in fluorescence quantum yield of basic fuchsin with silver nanoparticles prepared by femtosecond laser ablation.

    Science.gov (United States)

    Pathrose, Bini; Sahira, H; Nampoori, V P N; Radhakrishnan, P; Mujeeb, A

    2014-07-15

    Nano structured noble metals have very important applications in diverse fields such as photovoltaics, catalysis, electronic and magnetic devices, etc. In the present work, the application of dual beam thermal lens technique is employed for the determination of the absolute fluorescence quantum yield of the triaminotriphenylmethane dye, basic fuchsin in the presence of silver sol is studied. Silver sol is prepared by femtosecond laser ablation. It is observed that the presence of silver sol decreases the fluorescence quantum efficiency. The observed results are in line with the conclusion that the reduction in quantum yield in the quenching region is essentially due to the non-radiative relaxation of the absorbed energy. It is also observed that the presence of silver sol enhances the thermal lens signal which makes its detection easier at any concentration.

  1. A nanocryotron comparator can connect single-flux-quantum circuits to conventional electronics

    Science.gov (United States)

    Zhao, Qing-Yuan; McCaughan, Adam N.; Dane, Andrew E.; Berggren, Karl K.; Ortlepp, Thomas

    2017-04-01

    Integration with conventional electronics offers a straightforward and economical approach to upgrading existing superconducting technologies, such as scaling up superconducting detectors into large arrays and combining single flux quantum (SFQ) digital circuits with semiconductor logic gates and memories. However, direct output signals from superconducting devices (e.g., Josephson junctions) are usually not compatible with the input requirements of conventional devices (e.g., transistors). Here, we demonstrate the use of a single three-terminal superconducting-nanowire device, called the nanocryotron (nTron), as a digital comparator to combine SFQ circuits with mature semiconductor circuits such as complementary metal oxide semiconductor (CMOS) circuits. Since SFQ circuits can digitize output signals from general superconducting devices and CMOS circuits can interface existing CMOS-compatible electronics, our results demonstrate the feasibility of a general architecture that uses an nTron as an interface to realize a ‘super-hybrid’ system consisting of superconducting detectors, superconducting quantum electronics, CMOS logic gates and memories, and other conventional electronics.

  2. A nanoCryotron comparator can connect single-flux quantum circuits to conventional electronics

    CERN Document Server

    Zhao, Qing-Yuan; Dane, Andrew E; Berggren, Karl K; Ortlepp, Thomas

    2016-01-01

    Integration with conventional electronics offers a straightforward and economical approach to upgrading existing superconducting technologies, such as scaling up superconducting detectors into large arrays and combining single flux quantum (SFQ) digital circuits with semiconductor logic and memories. However, direct output signals from superconducting devices (e.g., Josephson junctions) are usually not compatible with the input requirements of conventional devices (e.g., transistors). Here, we demonstrate the use of a single three-terminal superconducting-nanowire device, called the nanocryotron (nTron), as a digital comparator to combine SFQ circuits with mature semiconductor circuits such as complementary metal oxide semiconductor (CMOS) circuits. Since SFQ circuits can digitize output signals from general superconducting devices and CMOS circuits can interface existing CMOS-compatible electronics, our results demonstrate the feasibility of a general architecture that uses an nTron as an interface to realiz...

  3. Absolute I(asterisk) quantum yields for the ICN A state by diode laser gain-vs-absorption spectroscopy

    Science.gov (United States)

    Hess, Wayne P.; Leone, Stephen R.

    1987-01-01

    Absolute I(asterisk) quantum yields have been measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The yields are obtained by the technique of time-resolved diode laser gain-vs-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 + or - 2 percent and it falls off to 53.4 + or - 2 percent and 44.0 + or - 4 percent at 284 and 248 nm, respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I(asterisk) quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I(asterisk) yields reported here. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I(asterisk) quantum yield results.

  4. Fluorescence Quantum Yield Measurements of Fluorescent Proteins: A Laboratory Experiment for a Biochemistry or Molecular Biophysics Laboratory Course

    Science.gov (United States)

    Wall, Kathryn P.; Dillon, Rebecca; Knowles, Michelle K.

    2015-01-01

    Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…

  5. Photophysical investigation of (D-π-A) DMHP dye: Dipole moments, photochemical quantum yield and fluorescence quantum yield, by solvatochromic shift methods and DFT studies

    Science.gov (United States)

    Asiri, Abdullah M.; Sobahi, Tariq R.; Osman, Osman I.; Khan, Salman A.

    2017-01-01

    (2E)-3-(3,4-dimethoxyphenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (DMHP) was synthesized by the reaction of 3,4-dimethoxy benzaldehyde with 1-(2-hydroxyphenyl) ethanone under microwave irradiation. The structure of DMHP was established experimentally by EI-MS, FT-IR, 1H and 13C NMR spectral studies and elemental analysis and theoretically. Electronic absorption and emission spectra of DMHP were studied in different solvents on the basis of polarities, and the obtain data were used to determine the solvatochromic properties such as extinction coefficient, oscillator strength, transition dipole moment, stokes shift, fluorescence quantum yield and photochemical quantum yield. The absorption and emission maxima were red-shifted when the polarity of the solvent was increased from dioxan to DMSO; in excellent agreement the DFT findings. The DMHP experimental intramolecular charge transfer (ICT) was complemented by a natural bond orbital (NBO) analysis. Fluorescence intensities of DMHP were increase and decrease in presence of CTAB and SDS, so DMHP was used to find out the critical micelle concentration (CMC) of CTAB and SDS.

  6. Nanomechanical method to gauge emission quantum yield applied to NV-centers in nanodiamond

    CERN Document Server

    Frimmer, Martin; Koenderink, A Femius

    2012-01-01

    We present a technique to nanomechanically vary the distance between a fluorescent source and a mirror, thereby varying the local density of optical states at the source position. Our method can therefore serve to measure the quantum efficiency of fluorophores. Application of our technique to NV defects in diamond nanocrystals shows that their quantum yield can significantly differ from unity. Relying on a lateral scanning mechanism with shear-force probe-sample distance control our technique is straightforwardly implemented in most state-of-the-art near-field microscopes.

  7. Fish growth, yield and economics of conventional feed and weed based polyculture in ponds

    Directory of Open Access Journals (Sweden)

    Md Asadujjaman

    2016-04-01

    Full Text Available Fish growth, yield and economics of polyculture were evaluated for six months from April to September, 2011 in ponds of Kushtia district, Bangladesh under 4 treatments of feeds and weeds as T0: rice bran, wheat bran and mustard oilcake; T1: Azolla; T2: Grass and T3: Banana leaf. Each treatment had 3 replications. Mean initial stocking weight of fishes like Hypophthalmichthyes molitrix, Catla catla, Labeo rohita, Cirrhinus mrigala, Cyprinus carpio, Ctenopharyngodon idella and Barbonymus gonionotus was 62, 64, 57, 54, 63, 65 and 25 g, respectively. Stocking density (11,115 fishes/ha, liming (250 kg/ha, basal fertilization (Cowdung, 1,500 kg/ha; urea, 60 kg/ha; and Triple Super Phosphate, TSP 60 kg/ha and periodic fertilization (Urea, 2.5 kg/ha/day; and TSP, 2.5 kg/ha/day were same for all the treatments. Water quality parameters (water temperature, transparency, dissolved oxygen, pH, alkalinity and free carbon dioxide were monitored fortnightly and fish growth parameters (weight gain and Specific Growth Rate, SGR were monitored monthly. Treatments did not vary significantly for the mean water quality parameters. Treatment T0 varied more significantly (P<0.05 for the mean final weight, weight gain, SGR, survival rate and yield for almost all the species except C. idella and B. gonionotus. Significantly highest CBR was recorded with treatment T1.

  8. Preparation of carbon quantum dots with a high quantum yield and the application in labeling bovine serum albumin

    Science.gov (United States)

    Liu, Pengpeng; Zhang, Changchang; Liu, Xiang; Cui, Ping

    2016-04-01

    An economic and green approach of manufacturing carbon quantum dots (CQDs) with a high quantum yield (denoted with HQY-CQDs) and the application in labeling bovine serum albumin (BSA) were described in detail in this work. Firstly, the cheap resources of citric acid and glycine were pyrolysed in drying oven for preparing the CQDs. Then the product was immersed in tetrahydrofuran for 8 h. HQY-CQDs were obtained by removing tetrahydrofuran from the supernate and were evaluated that they possessed a much higher quantum yield compared with that without dealing with tetrahydrofuran and a wonderful photo-bleaching resistance. Such HQY-CQDs could be functionalized by N-hydroxysuccinimide and successively combined with BSA covalently. Thus fluorescent labeling on BSA was realized. The HQY-CQDs were demonstrated with transmission electron microscopy and the chemical modification with N-hydroxysuccinimide was proved by infrared and X-ray photoelectron spectra. Labeling BSA with the HQY-CQDs was confirmed by gel electrophoresis and fluorescence imaging.

  9. Determining the Photoisomerization Quantum Yield of Photoswitchable Molecules in Solution and in the Solid State

    Science.gov (United States)

    Stranius, K.; Börjesson, K.

    2017-01-01

    Photoswitchable molecules are able to isomerize between two metastable forms through light stimuli. Originally being studied by photochemists, this type of molecule has now found a wide range of applications within physics, chemistry and biology. The extensive usage of photochromic molecules is due to the two isomers having fundamentally different physical and chemical properties. The most important attribute of a photoswitch is the photoisomerization quantum yield, which defines the efficiency of the photoisomerization event. Here we show how to determine the photoisomerization quantum yield in the solid state and in solution when taking thermal processes into account. The described method together with provided software allows for rapid and accurate determination of the isomerization process for this important class of molecules.

  10. The effect of axial ligands on the quantum yield of singlet oxygen of new silicon phthalocyanine

    Science.gov (United States)

    Lv, Huafei; Zhang, Xuemei; Yu, Xinxin; Pan, Sujuan; Xie, Shusen; Yang, Hongqin; Peng, Yiru

    2016-10-01

    The singlet oxygen (1O2) production abilitity is an important factor to assess their potential as effective of photosensitizers. In this paper, the 1O2 production rate, production rate constant and quantum yield of silicon(IV) phthalocyanine axially bearing 1-3 generation dendritic substituents were evaluated by a high performance liquid chromatographic method. The results show that the 1O2 production rate and production rate constant of these compounds increase gradually with dendritic generations increase. And the 1O2 quantum yield of silicon(IV) phthalocyanine with first generation dendritic ligand was the highest. This may be due to the isolation effect of the dendritic ligands on the phthalocyanine core. The parameters of the observed 1O2 production properties will provide valuable data for these dendrimer phthalocyanines as promising photosensitizer in PDT application.

  11. Luminescent carbon quantum dots with high quantum yield as a single white converter for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Feng, X. T.; Zhang, Y.; Liu, X. G., E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, F.; Wang, Y. L.; Yang, Y. Z., E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China)

    2015-11-23

    Carbon quantum dots (CQDs) with high quantum yield (51.4%) were synthesized by a one-step hydrothermal method using thiosalicylic acid and ethylenediamine as precursor. The CQDs have the average diameter of 2.3 nm and possess excitation-independent emission wavelength in the range from 320 to 440 nm excitation. Under an ultraviolet (UV) excitation, the CQDs aqueous solutions emit bright blue fluorescence directly and exhibit broad emission with a high spectral component ratio of 67.4% (blue to red intensity to total intensity). We applied the CQDs as a single white-light converter for white light emitting diodes (WLEDs) using a UV-LED chip as the excitation light source. The resulted WLED shows superior performance with corresponding color temperature of 5227 K and the color coordinates of (0.34, 0.38) belonging to the white gamut.

  12. Quantum Yield Determination Based on Photon Number Measurement, Protocols for Firefly Bioluminescence Reactions.

    Science.gov (United States)

    Niwa, Kazuki

    2016-01-01

    Quantum yield (QY), which is defined as the probability of photon production by a single bio/chemiluminescence reaction, is an important factor to characterize luminescence light intensity emitted diffusively from the reaction solution mixture. Here, methods to measure number of photons to determine QY according to the techniques of national radiometry standards are described. As an example, experiments using firefly bioluminescence reactions are introduced.

  13. Photoisomerization quantum yield of azobenzene-modified DNA depends on local sequence.

    Science.gov (United States)

    Yan, Yunqi; Wang, Xin; Chen, Jennifer I L; Ginger, David S

    2013-06-05

    Photoswitch-modified DNA is being studied for applications including light-harvesting molecular motors, photocontrolled drug delivery, gene regulation, and optically mediated assembly of plasmonic metal nanoparticles in DNA-hybridization assays. We study the sequence and hybridization dependence of the photoisomerization quantum yield of azobenzene attached to DNA via the popular d-threoninol linkage. Compared to free azobenzene we find that the quantum yield for photoisomerization from trans to cis form is decreased 3-fold (from 0.094 ± 0.004 to 0.036 ± 0.002) when the azobenzene is incorporated into ssDNA, and is further reduced 15-fold (to 0.0056 ± 0.0008) for azobenzene incorporated into dsDNA. In addition, we find that the quantum yield is sensitive to the local sequence including both specific mismatches and the overall sequence-dependent melting temperature (Tm). These results serve as design rules for efficient photoswitchable DNA sequences tailored for sensing, drug delivery, and energy-harvesting applications, while also providing a foundation for understanding phenomena such as photonically controlled hybridization stringency.

  14. Influence of conventional biochar and ageing biochar application to arable soil on soil fertility and plant yield

    Science.gov (United States)

    Dvořáčková, Helena; Záhora, Jaroslav; Elbl, Jakub; Kynický, Jindřich; Hladký, Jan; Brtnický, Martin

    2017-04-01

    Biochar represents very controversial material which is product of pyrolysis. According to many studies biochar has positive effect on physical and chemical properties such as pH, conductivity, aggregates stability etc. Unfortunately biochar is product of combustion, so it can content toxic substance as are aromatic compound. These substances may have a negative effect on yield and microbial activities in soil. Our aim was eliminated concentration of toxic compound but preserved positive effect of biochar on soil properties. We was ageing/ activating of biochar in water environment and for soil inoculum we used native soil from landscape. Moreover two types of biochar was tested by pot experiment with seven variants, where conventional biochar from residual biomass and ageing biochar were applied in different doses: 10 t/ha, 20t/ha and 50 t/ha. Pots were placed in green house for 90 days and after the end of experiment the following parameters of soil fertility, health and quality were evaluated: content of soil organic matter, arbuscular mycorrhizal colonisation of Lactuca sativa L. roots, leaching of mineral nitrogen, changes in plant available nutrient content, EC and pH. Above all the total yield of indicator plant was observed. The significant (P biochar didn't have positive effect on plant yield in comparison with ageing biochar. The positive effect of ageing biochar addition on soil fertility was directly proportional to the dose which were applied - increasing in dose of ageing biochar resulted in increase of plant yield. Moreover the special experimental containers were used, where we was able to monitor the development of root in soil with and without addition of biochar (conventional or ageing). The positive influence of ageing biochar addition into soil on development of Lactuca sativa L. roots was observed.

  15. Acetone photolysis at 248 nm revisited: pressure dependence of the CO and CO2 quantum yields.

    Science.gov (United States)

    Somnitz, H; Ufer, T; Zellner, R

    2009-10-14

    Pressure dependent CO and CO2 quantum yields in the laser pulse photolysis of acetone at 248 nm and T = 298 K have been measured directly using quantitative infrared diode laser absorption. The experiments cover the pressure range from 50 to 900 mbar. It is found that the quantum yields show a significant dependence on total pressure, with Phi(CO) decreasing from around 0.5 at 20 mbar to approximately 0.3 at 900 mbar. The corresponding CO2 yields as observed when O2 exists in the reaction mixture, exhibit exactly the opposite behaviour. For the sum of both a value of 1.05(-0.05)(+0.02) independent of pressure is obtained, showing that the sum of (Phi(CO) + Phi(CO2)) is a measure for the primary quantum yield in the photolysis of acetone. In addition, CO quantum yields and corresponding pressure dependences were measured in experiments using different bath gases including He, Ar, Kr, SF6, and O2 as third body colliders. The theoretical framework in which we discuss these data is based on our previous findings that the pressure dependence of the CO yield is a consequence of a stepwise fragmentation mechanism during which acetone decomposes initially into methyl and a vibrationally 'hot' acetyl radical, with the latter being able to decompose promptly into methyl plus CO. The pressure dependence of the CO yield then originates from the second step and is modelled quantitatively via statistical dynamical calculations using a combination of RRKM theory with a time-dependent master equation (ME) approach. From a comparison of experiment with theory the amount of excess energy in the vibrationally hot acetyl radicals (E* approximately 65 kJ mol(-1)) as well as the characteristic collision parameters for interaction of acetyl with the different bath gases were derived. Values of 90, 280, 310, 545, 550 and 1800 cm(-1) for the average energy transferred per downward collision for the bath gases He, Ar, Kr, O2, N2, and SF6, respectively, are obtained. The calculations also

  16. Measurement method for photoluminescent quantum yields of fluorescent organic dyes in polymethyl methacrylate for luminescent solar concentrators.

    Science.gov (United States)

    Wilson, L R; Richards, B S

    2009-01-10

    A method for measuring the photoluminescent quantum yields (PLQY) of luminescent organic dyes is presented. The self-absorption probability calculated at different dye concentrations is used to determine the absolute quantum yield from the observed values. The results for a range of commercially available dyes show high quantum yields, even at high concentrations, and an absence of quenching. The PLQY of several dye mixtures are also presented. The results indicate an absence of any reduction of PLQY in a dye mixture as compared with the individual PLQY of the dyes.

  17. Correlations between dissolved organic matter optical properties and quantum yields of singlet oxygen and hydrogen peroxide.

    Science.gov (United States)

    Dalrymple, Renée M; Carfagno, Amy K; Sharpless, Charles M

    2010-08-01

    Various aquatic dissolved organic matter (DOM) samples produce singlet oxygen (1O2) and hydrogen peroxide (H2O2) with quantum yields of 0.59 to 4.5% (1O2 at 365 nm) and 0.017 to 0.053% (H2O2, 300-400 nm integrated). The two species' yields have opposite pH dependencies and strong, but opposite, correlations with the E2/E3 ratio (A254 divided by A365). Linear regressions allow prediction of both quantum yields from E2/E3 in natural water samples with errors ranging from -3% to 60%. Experimental evidence and kinetic calculations indicate that less than six percent of the H2O2 is produced by reaction between 1O2 and DOM. The inverse relationship between the 1O2 and H2O2 yields is thus best explained by a model in which precursors to these species are populated competitively. A model is presented, which proposes that important precursors to H2O2 may be either charge-transfer or triplet states of DOM.

  18. High quantum yield graphene quantum dots decorated TiO{sub 2} nanotubes for enhancing photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Ailan, E-mail: qal67@163.com; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

    2016-07-01

    Highlights: • High concentration yellow GQDs and TiO{sub 2} nanotubes were achieved by a simple and green method. • High quantum yield GQDs enhanced the photodegradation capacity of TiO{sub 2} nanotube. • The catalytic performance of GQDs/TiO{sub 2} depends on the GQDs loading. • The improved photocatalytic activity of GQDs/TiO{sub 2} was attributed to three aspects. - Abstract: Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO{sub 2} nanotubes (GQDs/TiO{sub 2} NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600–800 nm. The photocatalytic activity of prepared GQDs/TiO{sub 2} NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO{sub 2} nanotubes (TiO{sub 2} NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV–vis light irradiation (λ = 380–780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO{sub 2} NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO{sub 2} NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO{sub 2} composite.

  19. Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets.

    Science.gov (United States)

    Ma, Xuedan; Diroll, Benjamin T; Cho, Wooje; Fedin, Igor; Schaller, Richard D; Talapin, Dmitri V; Gray, Stephen K; Wiederrecht, Gary P; Gosztola, David J

    2017-09-05

    Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g((2))(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicating the importance of surface passivation on NPL emission quality. Second-order photon correlation (g((2))(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. These findings reveal that by careful growth control and core-shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.

  20. Effects of ecological and conventional agricultural intensification practices on maize yields in sub-Saharan Africa under potential climate change

    Science.gov (United States)

    Folberth, Christian; Yang, Hong; Gaiser, Thomas; Liu, Junguo; Wang, Xiuying; Williams, Jimmy; Schulin, Rainer

    2014-04-01

    Much of Africa is among the world’s regions with lowest yields in staple food crops, and climate change is expected to make it more difficult to catch up in crop production in particular in the long run. Various agronomic measures have been proposed for lifting agricultural production in Africa and to adapt it to climate change. Here, we present a projection of potential climate change impacts on maize yields under different intensification options in Sub-Saharan Africa (SSA) using an agronomic model, GIS-based EPIC (GEPIC). Fallow and nutrient management options taken into account are (a) conventional intensification with high mineral N supply and a bare fallow, (b) moderate mineral N supply and cowpea rotation, and (c) moderate mineral N supply and rotation with a fast growing N fixing tree Sesbania sesban. The simulations suggest that until the 2040s rotation with Sesbania will lead to an increase in yields due to increasing N supply besides improving water infiltration and soils’ water holding capacity. Intensive cultivation with a bare fallow or an herbaceous crop like cowpea in the rotation is predicted to result in lower yields and increased soil erosion during the same time span. However, yields are projected to decrease in all management scenarios towards the end of the century, should temperature increase beyond critical thresholds. The results suggest that the effect of eco-intensification as a sole means of adapting agriculture to climate change is limited in Sub-Saharan Africa. Highly adverse temperatures would rather have to be faced by improved heat tolerant cultivars, while strongly adverse decreases in precipitation would have to be faced by expanding irrigation where feasible. While the evaluation of changes in agro-environmental variables like soil organic carbon, erosion, and soil humidity hints that these are major factors influencing climate change resilience of the field crop, no direct relationship between these factors, crop yields, and

  1. A general quantitative pH sensor developed with dicyandiamide N-doped high quantum yield graphene quantum dots.

    Science.gov (United States)

    Wu, Zhu Lian; Gao, Ming Xuan; Wang, Ting Ting; Wan, Xiao Yan; Zheng, Lin Ling; Huang, Cheng Zhi

    2014-04-07

    A general quantitative pH sensor for environmental and intracellular applications was developed by the facile hydrothermal preparation of dicyandiamide (DCD) N-doped high quantum yield (QY) graphene quantum dots (GQDs) using citric acid (CA) as the carbon source. The obtained N-doped GQDs have excellent photoluminesence (PL) properties with a relatively high QY of 36.5%, suggesting that N-doped chemistry could promote the QY of carbon nanomaterials. The possible mechanism for the formation of the GQDs involves the CA self-assembling into a nanosheet structure through intermolecular H-bonding at the initial stage of the reaction, and then the pure graphene core with many function groups formed through the dehydration between the carboxyl and hydroxyl of the intermolecules under hydrothermal conditions. These N-doped GQDs have low toxicity, and are photostable and pH-sensitive between 1.81 to 8.96, giving a general pH sensor with a wide range of applications from real water to intracellular contents.

  2. Photoisomerization dynamics of a rhodopsin-based molecule (potential molecular switch) with high quantum yields

    Science.gov (United States)

    Allen, Roland; Jiang, Chen-Wei; Zhang, Xiu-Xing; Fang, Ai-Ping; Li, Hong-Rong; Xie, Rui-Hua; Li, Fu-Li

    2015-03-01

    It is worthwhile to explore the detailed reaction dynamics of various candidates for molecular switches, in order to understand, e.g., the differences in quantum yields and switching times. Here we report density-functional-based simulations for the rhodopsin-based molecule 4-[4-Methylbenzylidene]-5-p-tolyl-3,4-dihydro-2H-pyrrole (MDP), synthesized by Sampedro et al. We find that the photoisomerization quantum yields are remarkably high: 82% for cis-to-trans, and 68% for trans-to-cis. The lifetimes of the S1 excited state in cis-MDP in our calculations are in the range of 900-1800 fs, with a mean value of 1270 fs, while the range of times required for full cis-to-trans isomerization are 1100-2000 fs, with a mean value of 1530 fs. In trans-MDP, the calculated S1 excited state lifetimes are 860-2140 fs, with a mean value of 1330 fs, and with the full trans-to-cis isomerization completed about 200 fs later. In both cases, the dominant reaction mechanism is rotation around the central C =C bond (connected to the pyrroline ring), and de-excitation occurs at an avoided crossing between the ground state and the lowest singlet state, near the midpoint of the rotational pathway. Research Fund for the Doctoral Program of Higher Education of China; Fundamental Research Funds for the Central Universities; Robert A. Welch Foundation; National Natural Science Foundation of China.

  3. Mathematical optimization approach for estimating the quantum yield distribution of a photochromic reaction in a polymer

    Science.gov (United States)

    Tanaka, Mirai; Yamashita, Takashi; Sano, Natsuki; Ishigaki, Aya; Suzuki, Tomomichi

    2017-01-01

    The convolution of a series of events is often observed for a variety of phenomena such as the oscillation of a string. A photochemical reaction of a molecule is characterized by a time constant, but materials in the real world contain several molecules with different time constants. Therefore, the kinetics of photochemical reactions of the materials are usually observed with a complexity comparable with those of theoretical kinetic equations. Analysis of the components of the kinetics is quite important for the development of advanced materials. However, with a limited number of exceptions, deconvolution of the observed kinetics has not yet been mathematically solved. In this study, we propose a mathematical optimization approach for estimating the quantum yield distribution of a photochromic reaction in a polymer. In the proposed approach, time-series data of absorbances are acquired and an estimate of the quantum yield distribution is obtained. To estimate the distribution, we solve a mathematical optimization problem to minimize the difference between the input data and a model. This optimization problem involves a differential equation constrained on a functional space as the variable lies in the space of probability distribution functions and the constraints arise from reaction rate equations. This problem can be reformulated as a convex quadratic optimization problem and can be efficiently solved by discretization. Numerical results are also reported here, and they verify the effectiveness of our approach.

  4. Mathematical optimization approach for estimating the quantum yield distribution of a photochromic reaction in a polymer

    Directory of Open Access Journals (Sweden)

    Mirai Tanaka

    2017-01-01

    Full Text Available The convolution of a series of events is often observed for a variety of phenomena such as the oscillation of a string. A photochemical reaction of a molecule is characterized by a time constant, but materials in the real world contain several molecules with different time constants. Therefore, the kinetics of photochemical reactions of the materials are usually observed with a complexity comparable with those of theoretical kinetic equations. Analysis of the components of the kinetics is quite important for the development of advanced materials. However, with a limited number of exceptions, deconvolution of the observed kinetics has not yet been mathematically solved. In this study, we propose a mathematical optimization approach for estimating the quantum yield distribution of a photochromic reaction in a polymer. In the proposed approach, time-series data of absorbances are acquired and an estimate of the quantum yield distribution is obtained. To estimate the distribution, we solve a mathematical optimization problem to minimize the difference between the input data and a model. This optimization problem involves a differential equation constrained on a functional space as the variable lies in the space of probability distribution functions and the constraints arise from reaction rate equations. This problem can be reformulated as a convex quadratic optimization problem and can be efficiently solved by discretization. Numerical results are also reported here, and they verify the effectiveness of our approach.

  5. Quantum Yields from Stationary States: Cis-Trans Isomerization of Model Retinal

    CERN Document Server

    Tscherbul, T V

    2014-01-01

    Cis-trans isomerization in retinal, the first step in vision, is often computationally studied from a time dependent viewpoint. Motivation for such studies lies in coherent pulsed laser experiments that explore the isomerization dynamics. However, such biological processes take place naturally in the presence of incoherent light, which excites a non-evolving mixture of stationary states. Here the isomerization problem is considered from the latter viewpoint and applied to a standard two-state, two-mode linear vibronic coupling model of retinal that explicitly includes a conical intersection between the ground and first excited electronic states. The calculated quantum yield at 500 nm agrees well with both the previous time-dependent calculations of Hahn and Stock (0.63) and with experiment ($0.65\\pm0.01$), as does its wavelength dependence. Significantly, the effects of environmental relaxation on the quantum yield in this well-established model are found to be negligible. The results make clear the connectio...

  6. Functionalization of quinoxalines by using TMP bases: preparation of tetracyclic heterocycles with high photoluminescene quantum yields.

    Science.gov (United States)

    Nafe, Julia; Herbert, Simon; Auras, Florian; Karaghiosoff, Konstantin; Bein, Thomas; Knochel, Paul

    2015-01-12

    Tetracyclic heterocycles that exhibit high photoluminescence quantum yields were synthesized by anellation reactions of mono-, di-, and trifunctionalized 2,3-dichloroquinoxalines. Thus, treatment of 2,3-dichloroquinoxaline with TMPLi (TMP = 2,2,6,6-tetramethylpiperidyl) allows a regioselective lithiation in position 5. Quenching with various electrophiles (iodine, (BrCl2 C)2 , allylic bromide, acid chloride, aryl iodide) leads to 5-functionalized 2,3-dichloroquinoxalines. Further functionalization in positions 6 and 8 can be achieved by using TMPLi or TMPMgCl⋅LiCl furnishing a range of new di- and tri-functionalized 2,3-dichloroquinoxalines. The chlorine atoms are readily substituted by anellation with 1,2-diphenols or 1,2-dithiophenols leading to a series of new tetracyclic compounds. These materials exhibit strong, tunable optical absorption and emission in the blue and green spectral region. The substituted O-heterocyclic compounds exhibit particularly high photoluminescence quantum yields of up to 90%, which renders them interesting candidates for fluorescence imaging applications.

  7. Study on Active Oxygen Quantum Yield, Insecticidal Activities and Stability of Diphenylthiophene

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-jun; XU Han-hong; WANG Yu-jian; HU Shan; ZHANG Zhi-xiang; ZHANG Yao-mou

    2007-01-01

    Active oxygen quantum yield, insecticidal activities and stability of diphenylthiophene were studied for the first time. The results showed that maximum diphenylthiophene absorbency variety was 0.438 after irradiation for 280 min and that of α-terthienyl (α-T) was 0.480 after irradiation for 200 min with UV. LC50 values ofdiphenylthiophene and α-T against 3rd instar larvae of Aedes albopictus were 9.18 × 10-3 and 9.69 × 10-4 μg mL-1 when treated for 24 h, respectively. LC50 values of the two chemicals against the 3rd instar larvae of Plutella xylostella were 267.87 and 222.22 μg mL-1 when treated for 24 h, respectively. The half lives of diphenylthiophene and α-T in methanol were 113.62 and 10.65 h. Difference between quantum yield of diphenylthiophene and α-T was not significant and they all possessed high toxicity to Aedes albopictus and Plutella xylostella, but diphenylthiophene was more stable than α-T. It could be concluded that diphenylthiophene has overcome the deficiency of photoactivated insecticides which degraded quickly in the environment and could not be applied on the field. Diphenylthiophene could kill the insects and accelerate the degradation rate of triazophos. The benefits of diphenylthiophene can be further exploited and applied on the field.

  8. Tuning a conventional quantum well laser by nonresonant laser field dressing of the active layer

    Energy Technology Data Exchange (ETDEWEB)

    Radu, Adrian; Eseanu, Nicoleta, E-mail: eseanu@physics.pub.ro; Spandonide, Ana

    2014-10-03

    Highlights: • The feasibility of tuning a GaAs QW laser by ILF dressing was investigated. • The effective mass approximation and finite differences method were used. • Conduction and valence subbands are found to be sensitive to the ILF dressing. • The interband transition energy of the active layer is blueshifted by the ILF. • Emitted wavelength, threshold current and characteristic temperature are discussed. - Abstract: Tunable semiconductor lasers may be considered as a critical technology for optical communications. We investigate the theoretical feasibility of tuning a conventional GaAs/Al{sub 0.2}Ga{sub 0.8}As quantum well laser emitting at 825 nm by non-resonant laser-dressing of the active layer. Conduction and valence subbands are sensitive to the intense dressing field and this effect can be used to blueshift the active interband transition. The laser-dressed electron and hole states are calculated in the effective mass approximation by using the finite difference method. Emitted wavelength, threshold current and characteristic temperature are discussed as functions of the dressing laser parameter and cavity length.

  9. Effect of PMMA impregnation on the fluorescence quantum yield of sol-gel glasses doped with quinine sulfate

    Science.gov (United States)

    Meneses-Nava, M. A.; Barbosa-García, O.; Díaz-Torres, L. A.; Chávez-Cerda, S.; Torres-Cisneros, M.; King, T. A.

    2001-08-01

    The fluorescence quantum yield of quinine sulfate in sol-gel and PMMA impregnated glasses is measured. The observed quantum yield improvement in the sol-gel matrix, compared to ethanol, is interpreted as a reduction of non-radiative relaxation channels by isolation of the molecules by the cage of the glass. PMMA impregnated sol-gel glasses show an extra improvement of the fluorescence yield, which is interpreted as a reduction of the free space and the rigid fixation of the molecules to the matrix.

  10. SU-E-T-191: First Principle Calculation of Quantum Yield in Photodynamic Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Abolfath, R; Guo, F; Chen, Z; Nath, R [Yale New Haven Hospital, New Haven, CT (United States)

    2014-06-01

    Purpose: We present a first-principle method to calculate the spin transfer efficiency in oxygen induced by any photon fields especially in MeV energy range. The optical pumping is mediated through photosensitizers, e.g., porphyrin and/or ensemble of quantum dots. Methods: Under normal conditions, oxygen molecules are in the relatively non-reactive triplet state. In the presence of certain photosensitizer compounds such as porphyrins, electromagnetic radiation of specific wavelengths can excite oxygen to highly reactive singlet state. With selective uptake of photosensitizers by certain malignant cells, photon irradiation of phosensitized tumors can lead to selective killing of cancer cells. This is the basis of photodynamic therapy (PDT). Despite several attempts, PDT has not been clinically successful except in limited superficial cancers. Many parameters such as photon energy, conjugation with quantum dots etc. can be potentially combined with PDT in order to extend the role of PDT in cancer management. The key quantity for this optimization is the spin transfer efficiency in oxygen by any photon field. The first principle calculation model presented here, is an attempt to fill this need. We employ stochastic density matrix description of the quantum jumps and the rate equation methods in quantum optics based on Markov/Poisson processes and calculate time evolution of the population of the optically pumped singlet oxygen. Results: The results demonstrate the feasibility of our model in showing the dependence of the optical yield in generating spin-singlet oxygen on the experimental conditions. The adjustable variables can be tuned to maximize the population of the singlet oxygen hence the efficacy of the photodynamic therapy. Conclusion: The present model can be employed to fit and analyze the experimental data and possibly to assist researchers in optimizing the experimental conditions in photodynamic therapy.

  11. Yield and economic performance of organic and conventional cotton-based farming systems--results from a field trial in India.

    Science.gov (United States)

    Forster, Dionys; Andres, Christian; Verma, Rajeev; Zundel, Christine; Messmer, Monika M; Mäder, Paul

    2013-01-01

    The debate on the relative benefits of conventional and organic farming systems has in recent time gained significant interest. So far, global agricultural development has focused on increased productivity rather than on a holistic natural resource management for food security. Thus, developing more sustainable farming practices on a large scale is of utmost importance. However, information concerning the performance of farming systems under organic and conventional management in tropical and subtropical regions is scarce. This study presents agronomic and economic data from the conversion phase (2007-2010) of a farming systems comparison trial on a Vertisol soil in Madhya Pradesh, central India. A cotton-soybean-wheat crop rotation under biodynamic, organic and conventional (with and without Bt cotton) management was investigated. We observed a significant yield gap between organic and conventional farming systems in the 1(st) crop cycle (cycle 1: 2007-2008) for cotton (-29%) and wheat (-27%), whereas in the 2(nd) crop cycle (cycle 2: 2009-2010) cotton and wheat yields were similar in all farming systems due to lower yields in the conventional systems. In contrast, organic soybean (a nitrogen fixing leguminous plant) yields were marginally lower than conventional yields (-1% in cycle 1, -11% in cycle 2). Averaged across all crops, conventional farming systems achieved significantly higher gross margins in cycle 1 (+29%), whereas in cycle 2 gross margins in organic farming systems were significantly higher (+25%) due to lower variable production costs but similar yields. Soybean gross margin was significantly higher in the organic system (+11%) across the four harvest years compared to the conventional systems. Our results suggest that organic soybean production is a viable option for smallholder farmers under the prevailing semi-arid conditions in India. Future research needs to elucidate the long-term productivity and profitability, particularly of cotton and

  12. Yield and economic performance of organic and conventional cotton-based farming systems--results from a field trial in India.

    Directory of Open Access Journals (Sweden)

    Dionys Forster

    Full Text Available The debate on the relative benefits of conventional and organic farming systems has in recent time gained significant interest. So far, global agricultural development has focused on increased productivity rather than on a holistic natural resource management for food security. Thus, developing more sustainable farming practices on a large scale is of utmost importance. However, information concerning the performance of farming systems under organic and conventional management in tropical and subtropical regions is scarce. This study presents agronomic and economic data from the conversion phase (2007-2010 of a farming systems comparison trial on a Vertisol soil in Madhya Pradesh, central India. A cotton-soybean-wheat crop rotation under biodynamic, organic and conventional (with and without Bt cotton management was investigated. We observed a significant yield gap between organic and conventional farming systems in the 1(st crop cycle (cycle 1: 2007-2008 for cotton (-29% and wheat (-27%, whereas in the 2(nd crop cycle (cycle 2: 2009-2010 cotton and wheat yields were similar in all farming systems due to lower yields in the conventional systems. In contrast, organic soybean (a nitrogen fixing leguminous plant yields were marginally lower than conventional yields (-1% in cycle 1, -11% in cycle 2. Averaged across all crops, conventional farming systems achieved significantly higher gross margins in cycle 1 (+29%, whereas in cycle 2 gross margins in organic farming systems were significantly higher (+25% due to lower variable production costs but similar yields. Soybean gross margin was significantly higher in the organic system (+11% across the four harvest years compared to the conventional systems. Our results suggest that organic soybean production is a viable option for smallholder farmers under the prevailing semi-arid conditions in India. Future research needs to elucidate the long-term productivity and profitability, particularly of cotton

  13. Determination of vis and NIR quantum yields of Nd{sup 3+}-activated garnets sensitized by Ce{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Möller, S.; Hoffmann, A.; Knaut, D.; Flottmann, J.; Jüstel, T., E-mail: tj@fh-muenster.de

    2015-02-15

    One of the most important quantities to describe the efficiency of luminescent materials is the external photoluminescence quantum yield (ePLQY) which is defined as the ratio of emitted to absorbed photons and thus describes the conversion efficiency of a given phosphor. In optical spectroscopy two methods of determination are applied: The absolute measurement conducted in an integrating sphere and a relative measurement based on a reference material with a known quantum yield. So far both methods are only described for phosphors in the UV and visible range of the electromagnetic spectrum. By using Nd{sup 3+} sensitized and Ce{sup 3+} activated garnets with the general formula (Y,Lu){sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+},Nd{sup 3+} ((Y,Lu)AG:Ce,Nd) we developed a method for the determination of the quantum yield in the near-infrared region. Therefore samples of different compositions have been synthesized and spectroscopically characterized. Starting point of the determination of the overall quantum yield is the determination of the quantum yield of the Ce{sup 3+} emission in the visible range by well-established methods. For using the proportionality of emission integral to the quantum yield it is necessary to scale and combine the measured spectra (460–1000 nm on the vis detector, and 900–1500 nm on the NIR detector). Furthermore, the accuracy of the method was evaluated not only by statistic calculations comprising the propagation of uncertainty but also by using branching ratio data of Nd{sup 3+} given in literature to check the generated overall emission spectra. - Highlights: • Method for determining the external quantum efficiency in the NIR range. • Sensitization and dopant ratio optimization of (Y,Lu)AG:Nd{sup 3+} by Ce{sup 3+}. • Application of branching ratios for evaluation of experimental ePLQY.

  14. Fluorescence quantum yield measurements of fluorescent proteins: a laboratory experiment for a biochemistry or molecular biophysics laboratory course.

    Science.gov (United States)

    Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K

    2015-01-01

    Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum.

  15. Microwave-assisted hydrothermal synthesis of highly luminescent ZnSe-based quantum dots with a quantum yield higher than 90%

    Science.gov (United States)

    Lee, Yong-Shin; Nakano, Kaoru; Bu, Hang-Beom; Gwi Kim, Dae

    2017-06-01

    Highly luminescent ZnSe-based quantum dots (QDs) were synthesized by a microwave-assisted hydrothermal method. The characteristics of the ZnSe precursor solution strongly influenced the photoluminescence (PL) quantum yields (QYs) of the QDs. The PL QY of ZnSe-core QDs synthesized under the optimum conditions reached 60%. Furthermore, the PL QY further increased to higher than 90% when a ZnS shell was applied to prepare ZnSe/ZnS-core/shell QDs.

  16. Gold Doping of Silver Nanoclusters: A 26-Fold Enhancement in the Luminescence Quantum Yield

    KAUST Repository

    Soldan, Giada

    2016-04-10

    A high quantum yield (QY) of photoluminescence (PL) in nanomaterials is necessary for a wide range of applications. Unfortunately, the weak PL and moderate stability of atomically precise silver nanoclusters (NCs) suppress their utility. Herein, we accomplished a ≥26-fold PL QY enhancement of the Ag29(BDT)12(TPP)4 cluster (BDT: 1,3-benzenedithiol; TPP: triphenylphosphine) by doping with a discrete number of Au atoms, producing Ag29-xAux(BDT)12(TPP)4, x=1-5. The Au-doped clusters exhibit an enhanced stability and an intense red emission around 660nm. Single-crystal XRD, mass spectrometry, optical, and NMR spectroscopy shed light on the PL enhancement mechanism and the probable locations of the Au dopants within the cluster.

  17. Novel fully-BODIPY functionalized cyclotetraphosphazene photosensitizers having high singlet oxygen quantum yields

    Science.gov (United States)

    Şenkuytu, Elif; Eçik, Esra Tanrıverdi

    2017-07-01

    Novel fully-BODIPY functionalized dendrimeric cyclotetraphosphazenes (FBCP 1 and 2) have been synthesized and characterized by 1H, 13C and 31P NMR spectroscopies. The photophysical and photochemical properties of FBCP 1 and 2 are investigated in dichloromethane solution. The effectiveness of singlet oxygen generation was measured for FBCP 1 and 2 by UV-Vis spectra monitoring of the solution of 1,3-diphenylisobenzofuran (DPBF), which is a well-known trapping molecule used in detection of singlet oxygen. FBCP 1 and 2 show high molar extinction coefficients in the NIR region, good singlet oxygen quantum yields and appropriate photo degradation. The data presented in the work indicate that the dendrimeric cyclotetraphosphazenes are effective singlet oxygen photosensitizers that might be used for various areas of applications such as photodynamic therapy and photocatalysis.

  18. Quantum yields for the light adaptations in Anabaena sensory rhodopsin and bacteriorhodopsin

    Science.gov (United States)

    Wada, Yoichiro; Kawanabe, Akira; Furutani, Yuji; Kandori, Hideki; Ohtani, Hiroyuki

    2008-02-01

    Archael-type rhodopsin has an all- trans or a 13- cis retinal. The light-induced interconversion between these two forms has been found in Anabaena sensory rhodopsin, even though only the photoreaction from the 13- cis form to the all- trans form exists in bacteriorhodopsin. In this study, we obtained the quantum yields for the 13- cis → all- trans and all- trans → 13- cis reactions of Anabaena sensory rhodopsin (0.24 ± 0.03 and 0.38 ± 0.07, respectively) and concluded that these values were independent of the wavelength of the excitation light as well as bacteriorhodopsin. In other words, no excess energy effects can be found in these reactions.

  19. Quantum yield variation across the three pathways of photosynthesis: not yet out of the dark.

    Science.gov (United States)

    Skillman, John B

    2008-01-01

    The convergent quantum yield hypothesis (CQY) assumes that thermodynamics and natural selection jointly limit variation in the maximum energetic efficiency of photosynthesis in low light under otherwise specified conditions (e.g. temperature and CO(2) concentration). A literature survey of photosynthetic quantum yield (phi) studies in terrestrial plants from C(3), C(4), and CAM photosynthetic types was conducted to test the CQY hypothesis. Broad variation in phi values from C(3) plants could partially be explained by accounting for whether the measuring conditions were permissive or restrictive for photorespiration. Assimilatory quotients (AQ), calculated from the CO(2) phi:O(2) phi ratios, indicated that 49% and 29% of absorbed light energy was allocated to carbon fixation and photorespiration in C(3) plants, respectively. The unexplained remainder (22%) may represent diversion to various other energy-demanding processes (e.g. starch synthesis, nitrogen assimilation). Individual and cumulative effects of these other processes on photosynthetic efficiency are poorly quantified. In C(4) plants, little variation in phi values was observed, consistent with the fact that C(4) plants exhibit little photorespiration. As before, AQ values indicate that 22% of absorbed light energy cannot be accounted for by carbon fixation in C(4) plants. Among all three photosynthetic types, the phi of photosynthesis in CAM plants is the least studied, appears to be highly variable, and may present the greatest challenge to the CQY hypothesis. The high amount of energy diverted to processes other than carbon fixation in C(3) and C(4) plants and the poor characterization of photosynthetic efficiency in CAM plants are significant deficiencies in our otherwise robust understanding of the energetics of terrestrial photoautotrophy.

  20. Sedimentation of Reversibly Interacting Macromolecules with Changes in Fluorescence Quantum Yield

    Science.gov (United States)

    Chaturvedi, Sumit K.; Zhao, Huaying; Schuck, Peter

    2017-04-01

    Sedimentation velocity analytical ultracentrifugation with fluorescence detection has emerged as a powerful method for the study of interacting systems of macromolecules. It combines picomolar sensitivity with high hydrodynamic resolution, and can be carried out with photoswitchable fluorophores for multi-component discrimination, to determine the stoichiometry, affinity, and shape of macromolecular complexes with dissociation equilibrium constants from picomolar to micromolar. A popular approach for data interpretation is the determination of the binding affinity by isotherms of weight-average sedimentation coefficients, sw. A prevailing dogma in sedimentation analysis is that the weight-average sedimentation coefficient from the transport method corresponds to the signal- and population-weighted average of all species. We show that this does not always hold true for systems that exhibit significant signal changes with complex formation - properties that may be readily encountered in practice, e.g., from a change in fluorescence quantum yield. Coupled transport in the reaction boundary of rapidly reversible systems can make significant contributions to the observed migration in a way that cannot be accounted for in the standard population-based average. Effective particle theory provides a simple physical picture for the reaction-coupled migration process. On this basis we develop a more general binding model that converges to the well-known form of sw with constant signals, but can account simultaneously for hydrodynamic co-transport in the presence of changes in fluorescence quantum yield. We believe this will be useful when studying interacting systems exhibiting fluorescence quenching, enhancement or Forster resonance energy transfer with transport methods.

  1. Quantum yield in blue-emitting anthracene derivatives: vibronic coupling density and transition dipole moment density.

    Science.gov (United States)

    Uejima, Motoyuki; Sato, Tohru; Yokoyama, Daisuke; Tanaka, Kazuyoshi; Park, Jong-Wook

    2014-07-21

    A theoretical design principle for enhancement of the quantum yield of light-emitting molecules is desired. For the establishment of the principle, we focused on the S1 states of blue-emitting anthracene derivatives: 2-methyl-9,10-di(2'-naphthyl)anthracene (MADN), 4,9,10-bis(3',5'-diphenylphenyl)anthracene (MAM), 9-(3',5'-diphenylphenyl)-10-(3'',5''-diphenylbiphenyl-4''-yl) anthracene (MAT), and 9,10-bis(3''',5'''-diphenylbiphenyl-4'-yl) anthracene (TAT) [Kim et al., J. Mater. Chem., 2008, 18, 3376]. The vibronic coupling constants and transition dipole moments were calculated and analyzed by using the concepts of vibronic coupling density (VCD) and transition dipole moment density (TDMD), respectively. It is found that the driving force of the internal conversions and vibrational relaxations originate mainly from the anthracenylene group. On the other hand, fluorescence enhancement results from the large torsional distortion of the side groups in the S1 state. The torsional distortion is caused by the diagonal vibronic coupling for the lowest-frequency mode in the Franck-Condon (FC) S1 state, which originates from a small portion of the electron density difference on the side groups. These findings lead to the following design principles for anthracene derivatives with a high quantum yield: (1) reduction in the electron density difference and overlap density between the S0 and S1 states in the anthracenylene group to suppress vibrational relaxation and radiationless transitions, respectively; (2) increase in the overlap density in the side group to enhance the fluorescence.

  2. Quantum Yields of OH From the Photolysis of HOOH in Ice

    Science.gov (United States)

    Chu, L.; Anastasio, C.

    2003-12-01

    Hydrogen peroxide (HOOH) is a common constituent of snow and cirrus ice clouds. Based on its behavior in aqueous solution, photolysis of HOOH on snow/ice should form hydroxyl radical (OH), a process that might be significant as a loss of HOOH as well as a source of OH. In turn, the formation of OH should lead to the oxidation of organic carbon and halides and subsequent release of these oxidation products (e.g., carbonyls, carboxylic acids, and reactive molecular halogens). Determining the importance and rate of OH generation from HOOH photolysis on snow and ice requires knowing the quantum yields for this process as a function of temperature and other environmental variables (e.g., pH and ionic strength). Since these values have not been previously measured, our goal in this work was to determine these quantum yields (i.e., Φ HOOH->OH). Our first step was to measure the molar absorptivities of HOOH between 274 K to 298 K so that we could extrapolate to ice temperatures. There was no temperature dependence of the HOOH molar absorptivity in our measurements, suggesting that the HOOH molar absorptivity is similar in the quasi-liquid layer of ice at low temperatures. Our initial experiments measuring Φ HOOH->OH as a function of temperature (243 - 268 K) show that the values roughly follow the same temperature dependence previously reported for aqueous solution (Zellner et al., 1990). In addition to these results we will also report how Φ HOOH->OH varies as a function of ionic strength and pH. The implications of our measurements for ice particle and snowpack chemistry will also be discussed. Zellner, R.; Exner, M.; Herrmann, H. J. Atmos. Chem. 1990, 10, 411.

  3. Consequences and Limitations of Conventional Computers and their Solutions through Quantum Computers

    Directory of Open Access Journals (Sweden)

    Nilesh BARDE

    2012-08-01

    Full Text Available Quantum computer is the current topic of research in the field of computational science, which uses principles of quantum mechanics. Quantum computers will be much more powerful than the classical computer due to its enormous computational speed. Recent developments in quantum computers which are based on the laws of quantum mechanics, shows different ways of performing efficient calculations along with the various results which are not possible on the classical computers in an efficient period of time. One of the most striking results that have obtained on the quantum computers is the prime factorization of the large integer in a polynomial time. The idea of involvement of the quantum mechanics for the computational purpose is outlined briefly in the present work that reflects the importance and advantages of the next generation of the 21st century classical computers, named as quantum computers, in terms of the cost as well as time period required for the computation purpose. Present paper presents a quantum computer simulator for executing the limitations of classical computer with respect to time and the number of digits of a composite integer used for calculating its prime factors.

  4. Organically vs conventionally grown winter wheat: effects on grain yield, technological quality, and on phenolic composition and antioxidant properties of bran and refined flour.

    Science.gov (United States)

    Mazzoncini, Marco; Antichi, Daniele; Silvestri, Nicola; Ciantelli, Giulia; Sgherri, Cristina

    2015-05-15

    Since organic food is widely assumed to have a better nutritional quality than conventional food, our aim was to study the effects of organic vs conventional cropping systems on yield and the phenolic composition of winter wheat cv. 'Bologna'. Although organic wheat yielded less than conventional wheat, mainly due to the nitrogen shortage, and its bread-making quality was lower, the cultivation system did not affect the total amounts of phenolics and phenolic acids. Of the eight phenolic acids identified, only ferulic acid was influenced by the cultivation system. Phenolic composition and quantity were significantly affected by the milling fraction (bran or white flour): phenolics were more concentrated in the bran, which showed the highest antioxidant power. Under the conditions adopted in this study, an organic cropping system can maintain or even increase the health properties of the wheat milled products, provided a reduction in grain yield is accepted.

  5. Quantum-limit linkage of ‘strange’ and conventional metal states of high-T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Krusin-Elbaum, L., E-mail: krusin@sci.ccny.cuny.edu [Department of Physics, The City College of New York, NY 10031 (United States); Shibauchi, T. [Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Kasahara, Y. [Quantum-Phase Electronics Center, University of Tokyo, Tokyo 113-8656 (Japan); Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Okazaki, R.; Matsuda, Y. [Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); McDonald, R.D.; Mielke, C.H. [NHMFL, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hasegawa, M. [Department of Materials Science and Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2013-10-15

    Highlights: • High magnetic field transport in high-Tc cuprate superconductors. • Field-temperature-doping map of the pseudogap state. • Crossover from non-Fermi-liquid to the conventional Fermi liquid in the overdoped regime. • Strange metal regime and magnetic field dependent quantum critical point. -- Abstract: The key to the nature of superconducting pairing in high-T{sub c} cuprates lies in understanding the transition to a conventional behavior when they are heavily doped. By using high magnetic fields, we show that the pseudogapped Tl{sub 2}Ba{sub 2}CuO{sub 6+x} becomes a conventional metal at heavy doping in a quantum phase transition, where the pseudogap boundary develops a thermodynamic divergence corresponding to a zero entropy jump. The critical doping point downshifts with magnetic field in unison with the suppression of T{sub c}. This implies that quantum critical fluctuations and magnetic degrees that destabilize the pseudogap are linked to the superconductivity with high T{sub c}.

  6. Exotic versus conventional scaling and universality in a disordered bilayer quantum heisenberg antiferromagnet.

    Science.gov (United States)

    Sknepnek, Rastko; Vojta, Thomas; Vojta, Matthias

    2004-08-27

    We present Monte Carlo simulations of a two-dimensional bilayer quantum Heisenberg antiferromagnet with random dimer dilution. In contrast with exotic scaling scenarios found in other random quantum systems, the quantum phase transition in this system is characterized by a finite-disorder fixed point with power-law scaling. After accounting for corrections to scaling, with a leading irrelevant exponent of omega approximately 0.48, we find universal critical exponents z=1.310(6) and nu=1.16(3). We discuss the consequences of these findings and suggest new experiments.

  7. Quantum Character of Electromagnetic Langmuir Oscillations in Conventional Electron-Ion Plasma

    Directory of Open Access Journals (Sweden)

    Boris Alexandrovich Veklenko

    2012-01-01

    Full Text Available It is shown that the low-temperature plasma near-thermodynamic equilibrium cannot be classical because of a quantum nature of the longitudinal electromagnetic field and electron interaction with Rayleigh-Jeans distribution of Langmuir waves. The theory requires introduction of a dimensionless quantum charge whose value is greater than unity leading to a liquid-like behavior of the plasma.

  8. Accounting for the decrease of photosystem photochemical efficiency with increasing irradiance to estimate quantum yield of leaf photosynthesis

    NARCIS (Netherlands)

    Yin, X.; Belay, D.; Putten, van der P.E.L.; Struik, P.C.

    2014-01-01

    Maximum quantum yield for leaf CO2 assimilation under limiting light conditions (UCO2LL) is commonly estimated as the slope of the linear regression of net photosynthetic rate against absorbed irradiance over a range of low-irradiance conditions. Methodological errors associated with this estimation

  9. Accounting for the decrease of photosystem photochemical efficiency with increasing irradiance to estimate quantum yield of leaf photosynthesis

    NARCIS (Netherlands)

    Yin, X.; Belay, D.; Putten, van der P.E.L.; Struik, P.C.

    2014-01-01

    Maximum quantum yield for leaf CO2 assimilation under limiting light conditions (UCO2LL) is commonly estimated as the slope of the linear regression of net photosynthetic rate against absorbed irradiance over a range of low-irradiance conditions. Methodological errors associated with this estimation

  10. Ultrastable green fluorescence carbon dots with a high quantum yield for bioimaging and use as theranostic carriers

    DEFF Research Database (Denmark)

    Yang, Chuanxu; Thomsen, Rasmus Peter; Ogaki, Ryosuke

    2015-01-01

    in biomedical applications. Oligoethylenimine (OEI)–β-cyclodextrin (βCD) Cdots were synthesised using a simple and fast heating method in phosphoric acid. The synthesised Cdots showed strong green fluorescence under UV excitation with a 30% quantum yield and exhibited superior stability over a wide pH range. We......Carbon dots (Cdots) have recently emerged as a novel platform of fluorescent nanomaterials. These carbon nanoparticles have great potential in biomedical applications such as bioimaging as they exhibit excellent photoluminescence properties, chemical inertness and low cytotoxicity in comparison...... to widely used semiconductor quantum dots. However, it remains a great challenge to prepare highly stable, water-soluble green luminescent Cdots with a high quantum yield. Herein we report a new synthesis route for green luminescent Cdots imbuing these desirable properties and demonstrate their potential...

  11. Yield and Quality of Sequentially Grown Cherry Tomato and Lettuce under Long-Term Conventional, Low-Input and Organic Soil Management Systems

    NARCIS (Netherlands)

    Moccia, S.; Chiesa, A.; Oberti, A.; Tittonell, P.A.

    2006-01-01

    Besides to conventional fertiliser use, organic and low-input technologies are being increasingly used for soil management in vegetable production. However, different factors operating during crop growth (i.e. the pre-harvest factors) and related to soil properties may affect yield and quality of ve

  12. CDOM Sources and Photobleaching Control Quantum Yields for Oceanic DMS Photolysis

    KAUST Repository

    Galí, Martí

    2016-11-14

    Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY) for DMS photolysis varied according to the quantity and quality of its photosensitizers, chiefly chromophoric dissolved organic matter (CDOM) and nitrate. AQY compiled from the literature and unpublished studies ranged across 3 orders of magnitude at the 330 nm reference wavelength. The smallest AQY(330) were observed in coastal waters receiving major riverine inputs of terrestrial CDOM (0.06-0.5 m3 (mol quanta)-1). In open-ocean waters, AQY(330) generally ranged between 1 and 10 m3 (mol quanta)-1. The largest AQY(330), up to 34 m3 (mol quanta)-1), were seen in the Southern Ocean potentially associated with upwelling. Despite the large AQY variability, daily photolysis rate constants at the sea surface spanned a smaller range (0.04-3.7 d-1), mainly because of the inverse relationship between CDOM absorption and AQY. Comparison of AQY(330) with CDOM spectral signatures suggests there is an interplay between CDOM origin (terrestrial versus marine) and photobleaching that controls variations in AQYs, with a secondary role for nitrate. Our results can be used for regional or large-scale assessment of DMS photolysis rates in future studies.

  13. Near-unity photoluminescence quantum yield in MoS2

    KAUST Repository

    Amani, Matin

    2015-11-26

    Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure of merit, the room-temperature photoluminescence quantum yield (QY), is extremely low.The prototypical 2D material molybdenum disulfide (MoS2) is reported to have a maximum QYof 0.6%, which indicates a considerable defect density. Herewe report on an air-stable, solution-based chemical treatment by an organic superacid, which uniformly enhances the photoluminescence and minority carrier lifetime of MoS2 monolayers by more than two orders of magnitude.The treatment eliminates defect-mediated nonradiative recombination, thus resulting in a finalQYofmore than 95%, with a longest-observed lifetime of 10.8 0.6 nanoseconds. Our ability to obtain optoelectronic monolayers with near-perfect properties opens the door for the development of highly efficient light-emitting diodes, lasers, and solar cells based on 2D materials.

  14. White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis

    Science.gov (United States)

    Meiling, Till T.; Cywiński, Piotr J.; Bald, Ilko

    2016-06-01

    In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst.

  15. Girdling effects on fruit set and quantum yield efficiency of PSII in two Citrus cultivars.

    Science.gov (United States)

    Rivas, F; Gravina, A; Agustí, M

    2007-04-01

    Girdling effects on fruitlet abscission, leaf chlorophyll, chlorophyll a fluorescence and carbohydrate concentration in various flowering and vegetative shoots were studied during natural fruit drop in two Citrus cultivars. Irrespective of shoot type, girdling delayed fruitlet abscission, but only fruitlets borne on leafy shoots had increased final fruit set. Chlorophyll a fluorescence analysis revealed differences in quantum yield efficiency of photosystem II of light adapted leaves (Phi(PSII)) among shoot types and in response to girdling. In young leaves of vegetative shoots, girdling decreased Phi(PSII), whereas Phi(PSII) increased from Day 30 after girdling in young leaves of leafy flowering shoots; however, Phi(PSII) did not change in mature leaves during fruit set in either control or girdled trees. Girdling altered leaf carbohydrate concentrations and the photosynthetic performance of the various shoot types. Our results indicate that, in Citrus, several carbohydrate-based regulatory mechanisms of photosynthesis coexist during carbohydrate accumulation brought about by girdling. It is concluded that the delay in fruitlet abscission and the increase in Phi(PSII )observed in girdled leafy flowering shoots are the mechanisms underlying the enhancement of fruit set after girdling.

  16. Action spectra of photosystems II and I and quantum yield of photosynthesis in leaves in State 1.

    Science.gov (United States)

    Laisk, Agu; Oja, Vello; Eichelmann, Hillar; Dall'Osto, Luca

    2014-02-01

    The spectral global quantum yield (YII, electrons/photons absorbed) of photosystem II (PSII) was measured in sunflower leaves in State 1 using monochromatic light. The global quantum yield of PSI (YI) was measured using low-intensity monochromatic light flashes and the associated transmittance change at 810nm. The 810-nm signal change was calibrated based on the number of electrons generated by PSII during the flash (4·O2 evolution) which arrived at the PSI donor side after a delay of 2ms. The intrinsic quantum yield of PSI (yI, electrons per photon absorbed by PSI) was measured at 712nm, where photon absorption by PSII was small. The results were used to resolve the individual spectra of the excitation partitioning coefficients between PSI (aI) and PSII (aII) in leaves. For comparison, pigment-protein complexes for PSII and PSI were isolated, separated by sucrose density ultracentrifugation, and their optical density was measured. A good correlation was obtained for the spectral excitation partitioning coefficients measured by these different methods. The intrinsic yield of PSI was high (yI=0.88), but it absorbed only about 1/3 of quanta; consequently, about 2/3 of quanta were absorbed by PSII, but processed with the low intrinsic yield yII=0.63. In PSII, the quantum yield of charge separation was 0.89 as detected by variable fluorescence Fv/Fm, but 29% of separated charges recombined (Laisk A, Eichelmann H and Oja V, Photosynth. Res. 113, 145-155). At wavelengths less than 580nm about 30% of excitation is absorbed by pigments poorly connected to either photosystem, most likely carotenoids bound in pigment-protein complexes.

  17. Grain yield losses in yellow-rusted durum wheat estimated using digital and conventional parameters under field conditions

    Institute of Scientific and Technical Information of China (English)

    Omar; Vergara-Diaz; Shawn; C.Kefauver; Abdelhalim; Elazab; Maria; Teresa; Nieto-Taladriz; José; Luis; Araus

    2015-01-01

    The biotrophic fungus Puccinia striiformis f. sp. tritici is the causal agent of the yellow rust in wheat. Between the years 2010–2013 a new strain of this pathogen(Warrior/Ambition),against which the present cultivated wheat varieties have no resistance, appeared and spread rapidly. It threatens cereal production in most of Europe. The search for sources of resistance to this strain is proposed as the most efficient and safe solution to ensure high grain production. This will be helped by the development of high performance and low cost techniques for field phenotyping. In this study we analyzed vegetation indices in the Red,Green, Blue(RGB) images of crop canopies under field conditions. We evaluated their accuracy in predicting grain yield and assessing disease severity in comparison to other field measurements including the Normalized Difference Vegetation Index(NDVI), leaf chlorophyll content, stomatal conductance, and canopy temperature. We also discuss yield components and agronomic parameters in relation to grain yield and disease severity.RGB-based indices proved to be accurate predictors of grain yield and grain yield losses associated with yellow rust(R2= 0.581 and R2= 0.536, respectively), far surpassing the predictive ability of NDVI(R2= 0.118 and R2= 0.128, respectively). In comparison to potential yield, we found the presence of disease to be correlated with reductions in the number of grains per spike, grains per square meter, kernel weight and harvest index. Grain yield losses in the presence of yellow rust were also greater in later heading varieties. The combination of RGB-based indices and days to heading together explained 70.9% of the variability in grain yield and 62.7% of the yield losses.

  18. Grain yield losses in yellow-rusted durum wheat estimated using digital and conventional parameters under field conditions

    Institute of Scientific and Technical Information of China (English)

    Omar Vergara-Diaz; Shawn C. Kefauver; Abdelhalim Elazab; Maria Teresa Nieto-Taladriz; José Luis Araus

    2015-01-01

    The biotrophic fungus Puccinia striiformis f. sp. tritici is the causal agent of the yellow rust in wheat. Between the years 2010–2013 a new strain of this pathogen (Warrior/Ambition), against which the present cultivated wheat varieties have no resistance, appeared and spread rapidly. It threatens cereal production in most of Europe. The search for sources of resistance to this strain is proposed as the most efficient and safe solution to ensure high grain production. This will be helped by the development of high performance and low cost techniques for field phenotyping. In this study we analyzed vegetation indices in the Red, Green, Blue (RGB) images of crop canopies under field conditions. We evaluated their accuracy in predicting grain yield and assessing disease severity in comparison to other field measurements including the Normalized Difference Vegetation Index (NDVI), leaf chlorophyll content, stomatal conductance, and canopy temperature. We also discuss yield components and agronomic parameters in relation to grain yield and disease severity. RGB-based indices proved to be accurate predictors of grain yield and grain yield losses associated with yellow rust (R2=0.581 and R2=0.536, respectively), far surpassing the predictive ability of NDVI (R2=0.118 and R2=0.128, respectively). In comparison to potential yield, we found the presence of disease to be correlated with reductions in the number of grains per spike, grains per square meter, kernel weight and harvest index. Grain yield losses in the presence of yellow rust were also greater in later heading varieties. The combination of RGB-based indices and days to heading together explained 70.9% of the variability in grain yield and 62.7%of the yield losses.

  19. Comparative tree growth, phenology and fruit yield of several Japanese plum cultivars in two newly established orchards, organic and conventionally managed

    Directory of Open Access Journals (Sweden)

    F. T. Arroyo

    2013-02-01

    Full Text Available The growth, phenology and fruit yield of 14 Japanese plum cultivars (Prunus salicina Lindl were studied in two newly established experimental orchards under organic and conventional management. The experiment was conducted during 2005-2011 in the province of Seville (SW Spain, an important region of Japanese plum culture. Trunk cross-section areas (TCSA, flowering, yield and tree defoliation before winter dormancy were analysed over several years. After one year, TCSA were larger in the organically managed orchard (OMO for most of the cultivars, in the next two years they were equal, and from the fourth year, several cultivars showed significantly larger TCSA in the conventionally managed orchard (CMO. Flowering in the conventional orchard started from 2 to 6 days before and lasted for 3 to 5 days more than in the OMO. Several cultivars produced significantly more fruit in the CMO, being the average fruit yield in the organic orchard about 72% of the conventionally managed orchard. Autumn defoliation was significantly advanced in the organic orchard, especially in cultivars highly susceptible to rust (Tranzschelia pruni spinosae, a disease not adequately controlled in the organic orchard.

  20. Comparative tree growth, penology and fruit yield of several Japanese plum cultivars in two newly established orchards, organic and conventionally managed

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo, F. T.; Jimenez-Bocanegra, J. A.; Garcia-Galavis, P. A.; Santamaria, C.; Camacho, M.; Castejon, M.; Perez-Romero, L. F.; Daza, A.

    2013-05-01

    The growth, penology and fruit yield of 14 Japanese plum cultivars (Prunus salicina Lindl) were studied in two newly established experimental orchards under organic and conventional management. The experiment was conducted during 2005-2011 in the province of Seville (SW Spain), an important region of Japanese plum culture. Trunk cross-section areas (TCSA), flowering, yield and tree defoliation before winter dormancy were analysed over several years. After one year, TCSA were larger in the organically managed orchard (OMO) for most of the cultivars, in the next two years they were equal, and from the fourth year, several cultivars showed significantly larger TCSA in the conventionally managed orchard (CMO). Flowering in the conventional orchard started from 2 to 6 days before and lasted for 3 to 5 days more than in the OMO. Several cultivars produced significantly more fruit in the CMO, being the average fruit yield in the organic orchard about 72% of the conventionally managed orchard. Autumn defoliation was significantly advanced in the organic orchard, especially in cultivars highly susceptible to rust (Tranzschelia pruni spinosae), a disease not adequately controlled in the organic orchard. (Author) 35 refs.

  1. Comparison on extraction yield of sennoside A and sennoside B from senna (Cassia angustifolia) using conventional and non conventional extraction techniques and their quantification using a validated HPLC-PDA detection method.

    Science.gov (United States)

    Dhanani, Tushar; Singh, Raghuraj; Reddy, Nagaraja; Trivedi, A; Kumar, Satyanshu

    2017-05-01

    Senna is an important medicinal plant and is used in many Ayurvedic formulations. Dianthraquinone glucosides are the main bioactive phytochemicals present in leaves and pods of senna. The extraction efficiency in terms of yield and composition of the extract of senna prepared using both conventional (cold percolation at room temperature and refluxing) and non conventional (ultrasound and microwave assisted solvent extraction as well as supercritical fluid extraction) techniques were compared in the present study. Also a rapid reverse phase HPLC-PDA detection method was developed and validated for the simultaneous determination of sennoside A and sennoside B in the different extracts of senna leaves. Ultrasound and microwave assisted solvent extraction techniques were more effective in terms of yield and composition of the extracts compared to cold percolation at room temperature and refluxing methods of extraction.

  2. Foliar Spray of Nitrogen Fertilizer on Raised Bed Increases Yield of Transplanted Aman Rice over Conventional Method

    OpenAIRE

    M. H. M. Bhuyan; Mst. R. Ferdousi; Iqbal, M. T.

    2012-01-01

    Bed planting with foliar nitrogen fertilizer application of rice production systems is very new, and research on it is still at introductory phase. Influence of foliar application of nitrogen fertilizer on growth and yield of transplanted aman rice and evaluation of water and fertilizer application efficiency of rice-fallow-rice cropping system were investigated under raised bed cultivation method. Results showed that foliar spray in bed planting method increased grain yield of transplanted a...

  3. Biosolar cells: global artificial photosynthesis needs responsive matrices with quantum coherent kinetic control for high yield.

    Science.gov (United States)

    Purchase, R L; de Groot, H J M

    2015-06-06

    This contribution discusses why we should consider developing artificial photosynthesis with the tandem approach followed by the Dutch BioSolar Cells consortium, a current operational paradigm for a global artificial photosynthesis project. We weigh the advantages and disadvantages of a tandem converter against other approaches, including biomass. Owing to the low density of solar energy per unit area, artificial photosynthetic systems must operate at high efficiency to minimize the land (or sea) area required. In particular, tandem converters are a much better option than biomass for densely populated countries and use two photons per electron extracted from water as the raw material into chemical conversion to hydrogen, or carbon-based fuel when CO2 is also used. For the average total light sum of 40 mol m(-2) d(-1) for The Netherlands, the upper limits are many tons of hydrogen or carbon-based fuel per hectare per year. A principal challenge is to forge materials for quantitative conversion of photons to chemical products within the physical limitation of an internal potential of ca 2.9 V. When going from electric charge in the tandem to hydrogen and back to electricity, only the energy equivalent to 1.23 V can be stored in the fuel and regained. A critical step is then to learn from nature how to use the remaining difference of ca 1.7 V effectively by triple use of one overpotential for preventing recombination, kinetic stabilization of catalytic intermediates and finally generating targeted heat for the release of oxygen. Probably the only way to achieve this is by using bioinspired responsive matrices that have quantum-classical pathways for a coherent conversion of photons to fuels, similar to what has been achieved by natural selection in evolution. In appendix A for the expert, we derive a propagator that describes how catalytic reactions can proceed coherently by a convergence of time scales of quantum electron dynamics and classical nuclear dynamics. We

  4. Yield and apparent dry matter and nitrogen balances for muskmelon in a long-term comparison between an organic and a conventional low input cropping system

    Directory of Open Access Journals (Sweden)

    Michela Farneselli

    2015-09-01

    Full Text Available Nine-year yields and apparent balances of dry matter and nitrogen (N are reported for muskmelon cultivated in a long-term comparison trial between an organic and a conventional low input system in Central Italy. In every year, yield, above ground biomass and N accumulation of each cash crop, green manure and weeds, and the partitioning between marketable yield and crop residues were determined. Apparent dry matter and nitrogen balances were calculated at the end of each crop cycle by taking into account the amounts of dry matter and ex novo N supplied to the system as green manure legume Ndfa (i.e., an estimate of N derived from the atmosphere via symbiotic fixation and fertilisers, and those removed with marketable yield. Differences between systems varied across years. On average, organic muskmelon yielded 16% less than the conventional one, while the fruit quality was similar in the two cropping systems. Fruit ripening began one week later and it was more scaled than in the crop grown conventionally. This was the consequence of a slow initial growth of the organic crop, due to inadequate green manure N total supply or timing of N release. Moreover such a wide spaced crop (0.5 plants m–2, in rows 2 m apart was not efficient in intercepting N released from green manure biomass incorporated broadcast. Compared to the conventional crop management, the organic crop management resulted in much higher organic matter supply to the soil and in higher residual N after harvest. Thus, the choice of cultivating wheat just after melon to prevent postharvest residual N loss appears a key strategy especially in organic systems. Fall-winter green manure crops contributed to the self-sufficiency of the organic system by supplying muskmelon with either N absorbed from the soil or ex novo legume Ndfa.

  5. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  6. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  7. Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

    Science.gov (United States)

    Monje, O.; Bugbee, B.

    1998-01-01

    The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

  8. Predicting fluorescence quantum yield for anisole at elevated temperatures and pressures

    Science.gov (United States)

    Wang, Q.; Tran, K. H.; Morin, C.; Bonnety, J.; Legros, G.; Guibert, P.

    2017-07-01

    Aromatic molecules are promising candidates for using as a fluorescent tracer for gas-phase scalar parameter diagnostics in a drastic environment like engines. Along with anisole turning out an excellent temperature tracer by Planar Laser-Induced Fluorescence (PLIF) diagnostics in Rapid Compression Machine (RCM), its fluorescence signal evolution versus pressure and temperature variation in a high-pressure and high-temperature cell have been reported in our recent paper on Applied Phys. B by Tran et al. Parallel to this experimental study, a photophysical model to determine anisole Fluorescence Quantum Yield (FQY) is delivered in this paper. The key to development of the model is the identification of pressure, temperature, and ambient gases, where the FQY is dominated by certain processes of the model (quenching effect, vibrational relaxation, etc.). In addition to optimization of the vibrational relaxation energy cascade coefficient and the collision probability with oxygen, the non-radiative pathways are mainly discussed. The common non-radiative rate (intersystem crossing and internal conversion) is simulated in parametric form as a function of excess vibrational energy, derived from the data acquired at different pressures and temperatures from the literature. A new non-radiative rate, namely, the equivalent Intramolecular Vibrational Redistribution or Randomization (IVR) rate, is proposed to characterize anisole deactivated processes. The new model exhibits satisfactory results which are validated against experimental measurements of fluorescence signal induced at a wavelength of 266 nm in a cell with different bath gases (N2, CO2, Ar and O2), a pressure range from 0.2 to 4 MPa, and a temperature range from 473 to 873 K.

  9. Effect of farming systems on the yield, quality parameters and sensory properties of conventionally and organically grown potato (Solanum tuberosum L.) tubers.

    Science.gov (United States)

    Brazinskiene, V; Asakaviciute, R; Miezeliene, A; Alencikiene, G; Ivanauskas, L; Jakstas, V; Viskelis, P; Razukas, A

    2014-02-15

    The objectives of this two-year research were to study the impact of two different farming types, conventional and organic, on the yield and sensory properties of five Lithuanian varieties of potato tuber. The parameters and properties examined were: phenolic acids; dry matter and starch content; and the spread and intensity of Phytophthora infestans growth. It was determined that potato yield fluctuates with the variety, but for conventional farming it is significantly (porganic farming. The farming type has no significant effect (p>0.05) on the content of phenolic acids. No significant effect (p>0.05) of farming type on dry matter and starch content, or sensory properties was found. No significant relation (p>0.05) was found between the content of phenolic acids and P. infestans spread. The spread of P. infestans was faster and infection was heavier in organically grown potatoes.

  10. Structure-Triggered High Quantum Yield Luminescence and Switchable Dielectric Properties in Manganese(II) Based Hybrid Compounds.

    Science.gov (United States)

    Wang, Zhong-Xia; Li, Peng-Fei; Liao, Wei-Qiang; Tang, Yuanyuan; Ye, Heng-Yun; Zhang, Yi

    2016-04-01

    Two new manganese(II) based organic-inorganic hybrid compounds, C11H21Cl3MnN2 (1) and C11H22Cl4MnN2 (2), with prominent photoluminescence and dielectric properties were synthesized by solvent modulation. Compound 1 with novel trigonal bipyramidal geometry exhibits bright red luminescence with a lifetime of 2.47 ms and high quantum yield of 35.8 %. Compound 2 with tetrahedral geometry displays intense long-lived (1.54 ms) green light emission with higher quantum yield of 92.3 %, accompanied by reversible solid-state phase transition at 170 K and a distinct switchable dielectric property. The better performance of 2 results from the structure, including a discrete organic cation moiety and inorganic metal anion framework, which gives the cations large freedom of motion.

  11. Quantum yield of Cl∗ (21/2) production in the gas phase photolysis of CCl4 in the ultraviolet

    Indian Academy of Sciences (India)

    Manish Tak; Manabendra Chandra; Dulal Senapati; Puspendu K Das

    2006-07-01

    In this paper, we have probed the dynamics of chlorine atom production from the gas phase photodissociation of carbon tetrachloride at 222 and 235 nm. The quantum yield, * of Cl∗ (21/2) production has been determined by probing the nascent concentrations of both excited (21/2) and ground state (23/2) chlorine atoms by suitable resonance-enhanced multiphoton ionization (REMPI) detection schemes. Although at the photolysis wavelengths the absorption of carbon tetrachloride is weak, significant amounts of Cl∗ are produced. Surprisingly, the quantum yield of Cl∗ production does not follow the absorption spectrum closely, which gives rise to the possibility of an indirect dissociation mechanism present in CCl4 along with direct dissociation at these ultraviolet wavelengths.

  12. Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry

    DEFF Research Database (Denmark)

    Meusinger, Carl; Berhanu, Tesfaye A.; Erbland, Joseph

    2014-01-01

    Post-depositional processes alter nitrate concentration and nitrate isotopic composition in the top layers of snow at sites with low snow accumulation rates, such as Dome C, Antarctica. Available nitrate ice core records can provide input for studying past atmospheres and climate if such processes...... undergoing secondary (recombination) chemistry. Modeled NOx emissions may increase significantly above measured values due to the observed quantum yield in this study. The apparent quantum yield in the 200 nm band was found to be ∼ 1%, much lower than reported for aqueous chemistry. A companion paper...... presents an analysis of the change in isotopic composition of snowpack nitrate based on the same samples as in this study....

  13. Quantum yields for OH production from 193 and 248 nm photolysis of HNO3 and H2O2

    Science.gov (United States)

    Schiffman, A.; Nelson, D. D., Jr.; Nesbitt, D. J.

    1993-05-01

    Flash kinetic spectroscopy in a flow tube is used to measure at room temperature the absolute yields for OH production from 193 and 248 nm photolysis of HNO3 and H2O2. The OH radicals are produced by excimer laser photolysis and probed via direct absorption of high resolution tunable IR laser light. The results indicate quantum yields for both precursors at both wavelengths which are less than the maximum possible values of 1 for H2O2. The present measurements are discussed in light of contrasting results suggested from other work.

  14. Yield of glyphosate-resistant sugar beets and efficiency of weed management systems with glyphosate and conventional herbicides under German and Polish crop production.

    Science.gov (United States)

    Nichterlein, Henrike; Matzk, Anja; Kordas, Leszek; Kraus, Josef; Stibbe, Carsten

    2013-08-01

    In sugar beet production, weed control is one of the most important and most expensive practices to ensure yield. Since glyphosate-resistant sugar beets are not yet approved for cultivation in the EU, little commercial experience exists with these sugar beets in Europe. Experimental field trials were conducted at five environments (Germany, Poland, 2010, 2011) to compare the effects of glyphosate with the effects of conventional weed control programs on the development of weeds, weed control efficiency and yield. The results show that the glyphosate weed control programs compared to the conventional methods decreased not only the number of herbicide applications but equally in magnitude decreased the dosage of active ingredients. The results also showed effective weed control with glyphosate when the weed covering was greater and sugar beets had a later growth stage of four true leaves. Glyphosate-resistant sugar beets applied with the glyphosate herbicide two or three times had an increase in white sugar yield from 4 to 18 % in comparison to the high dosage conventional herbicide systems. In summary, under glyphosate management sugar beets can positively contribute to the increasingly demanding requirements regarding efficient sugar beet cultivation and to the demands by society and politics to reduce the use of chemical plant protection products in the environment.

  15. Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Meusinger, Carl; Johnson, Matthew S. [Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Berhanu, Tesfaye A.; Erbland, Joseph; Savarino, Joel, E-mail: jsavarino@lgge.obs.ujf-grenoble.fr [Univ. Grenoble Alpes, LGGE, F-38000 Grenoble (France); CNRS, LGGE, F-38000 Grenoble (France)

    2014-06-28

    Post-depositional processes alter nitrate concentration and nitrate isotopic composition in the top layers of snow at sites with low snow accumulation rates, such as Dome C, Antarctica. Available nitrate ice core records can provide input for studying past atmospheres and climate if such processes are understood. It has been shown that photolysis of nitrate in the snowpack plays a major role in nitrate loss and that the photolysis products have a significant influence on the local troposphere as well as on other species in the snow. Reported quantum yields for the main reaction spans orders of magnitude – apparently a result of whether nitrate is located at the air-ice interface or in the ice matrix – constituting the largest uncertainty in models of snowpack NO{sub x} emissions. Here, a laboratory study is presented that uses snow from Dome C and minimizes effects of desorption and recombination by flushing the snow during irradiation with UV light. A selection of UV filters allowed examination of the effects of the 200 and 305 nm absorption bands of nitrate. Nitrate concentration and photon flux were measured in the snow. The quantum yield for loss of nitrate was observed to decrease from 0.44 to 0.003 within what corresponds to days of UV exposure in Antarctica. The superposition of photolysis in two photochemical domains of nitrate in snow is proposed: one of photolabile nitrate, and one of buried nitrate. The difference lies in the ability of reaction products to escape the snow crystal, versus undergoing secondary (recombination) chemistry. Modeled NO{sub x} emissions may increase significantly above measured values due to the observed quantum yield in this study. The apparent quantum yield in the 200 nm band was found to be ∼1%, much lower than reported for aqueous chemistry. A companion paper presents an analysis of the change in isotopic composition of snowpack nitrate based on the same samples as in this study.

  16. Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry.

    Science.gov (United States)

    Meusinger, Carl; Berhanu, Tesfaye A; Erbland, Joseph; Savarino, Joel; Johnson, Matthew S

    2014-06-28

    Post-depositional processes alter nitrate concentration and nitrate isotopic composition in the top layers of snow at sites with low snow accumulation rates, such as Dome C, Antarctica. Available nitrate ice core records can provide input for studying past atmospheres and climate if such processes are understood. It has been shown that photolysis of nitrate in the snowpack plays a major role in nitrate loss and that the photolysis products have a significant influence on the local troposphere as well as on other species in the snow. Reported quantum yields for the main reaction spans orders of magnitude - apparently a result of whether nitrate is located at the air-ice interface or in the ice matrix - constituting the largest uncertainty in models of snowpack NOx emissions. Here, a laboratory study is presented that uses snow from Dome C and minimizes effects of desorption and recombination by flushing the snow during irradiation with UV light. A selection of UV filters allowed examination of the effects of the 200 and 305 nm absorption bands of nitrate. Nitrate concentration and photon flux were measured in the snow. The quantum yield for loss of nitrate was observed to decrease from 0.44 to 0.003 within what corresponds to days of UV exposure in Antarctica. The superposition of photolysis in two photochemical domains of nitrate in snow is proposed: one of photolabile nitrate, and one of buried nitrate. The difference lies in the ability of reaction products to escape the snow crystal, versus undergoing secondary (recombination) chemistry. Modeled NOx emissions may increase significantly above measured values due to the observed quantum yield in this study. The apparent quantum yield in the 200 nm band was found to be ∼1%, much lower than reported for aqueous chemistry. A companion paper presents an analysis of the change in isotopic composition of snowpack nitrate based on the same samples as in this study.

  17. Photolysis quantum yield measurements in the near-UV; a critical analysis of 1-(2-nitrophenyl)ethyl photochemistry.

    Science.gov (United States)

    Corrie, John E T; Kaplan, Jack H; Forbush, Biff; Ogden, David C; Trentham, David R

    2016-05-11

    The photolysis quantum yield, Qp, of 1-(2-nitrophenyl)ethyl phosphate (caged Pi) measured in the near-UV (342 nm peak with 60 nm half-bandwidth) is 0.53 and is based on results reported in 1978 (Biochemistry, 17, 1929-1935). This article amplifies methodology for determining that Qp in view of different recent estimates. Some general principles together with other examples relating to measurement of Qp values are discussed together with their relevance to biological research.

  18. Tomato (Lycopersicon esculentum, cv CXD271BIO) yield and quality during converion from conventional to organic production

    OpenAIRE

    Nardo, N.; Foddai, MS; E.Azzini; Baiamonte, I; Di Ferdinando, S; Paoletti, S.; Vizioli, V; Paoletti, F.

    2011-01-01

    The conversion of a conventional farm to the methods of the organic farming is a very critical stage of technical and economical investment. From an agronomical point of view, usually the conversion needs a very different length of time with respect to that set by the regulation, because the organic farming is based on the soil fertility and, in general, on the preservation at the equilibrium of the farm’s ecosystem. These elements affect time and method of the conversions that, although base...

  19. Biosolar cells: global artificial photosynthesis needs responsive matrices with quantum coherent kinetic control for high yield

    Science.gov (United States)

    Purchase, R. L.; de Groot, H. J. M.

    2015-01-01

    This contribution discusses why we should consider developing artificial photosynthesis with the tandem approach followed by the Dutch BioSolar Cells consortium, a current operational paradigm for a global artificial photosynthesis project. We weigh the advantages and disadvantages of a tandem converter against other approaches, including biomass. Owing to the low density of solar energy per unit area, artificial photosynthetic systems must operate at high efficiency to minimize the land (or sea) area required. In particular, tandem converters are a much better option than biomass for densely populated countries and use two photons per electron extracted from water as the raw material into chemical conversion to hydrogen, or carbon-based fuel when CO2 is also used. For the average total light sum of 40 mol m−2 d−1 for The Netherlands, the upper limits are many tons of hydrogen or carbon-based fuel per hectare per year. A principal challenge is to forge materials for quantitative conversion of photons to chemical products within the physical limitation of an internal potential of ca 2.9 V. When going from electric charge in the tandem to hydrogen and back to electricity, only the energy equivalent to 1.23 V can be stored in the fuel and regained. A critical step is then to learn from nature how to use the remaining difference of ca 1.7 V effectively by triple use of one overpotential for preventing recombination, kinetic stabilization of catalytic intermediates and finally generating targeted heat for the release of oxygen. Probably the only way to achieve this is by using bioinspired responsive matrices that have quantum–classical pathways for a coherent conversion of photons to fuels, similar to what has been achieved by natural selection in evolution. In appendix A for the expert, we derive a propagator that describes how catalytic reactions can proceed coherently by a convergence of time scales of quantum electron dynamics and classical nuclear dynamics

  20. Radiation from relativistic electrons in "light" and in conventional undulators. Classical and quantum approaches

    Science.gov (United States)

    Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strokov, S. A.

    2016-07-01

    A photon spectrum of undulator radiation (UR) is calculated in the semi-classical approach. The UR intensity spectrum is determined by an electron trajectory in the undulator neglecting by energy losses for radiation. Using the Planck's law, the UR photon spectrum can be calculated from the classical intensity spectrum both for linear and nonlinear regimes. The radiation of an electron in a field of strong electromagnetic wave (radiation in the "light" undulator) is considered in the quantum electromagnetic frame. Comparison of results obtained by both approaches has been shown that UR spectra in the whole cone coincide with high accuracy for the case xbeam were simulated with taking into account the discrete process of photon emission along an electron trajectory in both kinds of undulators.

  1. Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through use of millisecond single pulse excitation with high peak power

    DEFF Research Database (Denmark)

    Liu, Haichun; Xu, Can T.; Dumlupinar, Gökhan;

    2013-01-01

    quantum yield that is utilized by upconverting nanoparticles for generating this near infrared upconversion emission. The pulsed excitation approach thus promises previously unreachable imaging depths and shorter data acquisition times compared with continuous wave excitation, while simultaneously keeping...

  2. Multiple exciton generation for photoelectrochemical hydrogen evolution reactions with quantum yields exceeding 100%

    Science.gov (United States)

    Yan, Yong; Crisp, Ryan W.; Gu, Jing; Chernomordik, Boris D.; Pach, Gregory F.; Marshall, Ashley R.; Turner, John A.; Beard, Matthew C.

    2017-04-01

    Multiple exciton generation (MEG) in quantum dots (QDs) has the potential to greatly increase the power conversion efficiency in solar cells and in solar-fuel production. During the MEG process, two electron-hole pairs (excitons) are created from the absorption of one high-energy photon, bypassing hot-carrier cooling via phonon emission. Here we demonstrate that extra carriers produced via MEG can be used to drive a chemical reaction with quantum efficiency above 100%. We developed a lead sulfide (PbS) QD photoelectrochemical cell that is able to drive hydrogen evolution from aqueous Na2S solution with a peak external quantum efficiency exceeding 100%. QD photoelectrodes that were measured all demonstrated MEG when the incident photon energy was larger than 2.7 times the bandgap energy. Our results demonstrate a new direction in exploring high-efficiency approaches to solar fuels.

  3. Broadband spectroscopy with external cavity quantum cascade lasers beyond conventional absorption measurements.

    Science.gov (United States)

    Lambrecht, Armin; Pfeifer, Marcel; Konz, Werner; Herbst, Johannes; Axtmann, Felix

    2014-05-07

    Laser spectroscopy is a powerful tool for analyzing small molecules, i.e. in the gas phase. In the mid-infrared spectral region quantum cascade lasers (QCLs) have been established as the most frequently used laser radiation source. Spectroscopy of larger molecules in the gas phase, of complex mixtures, and analysis in the liquid phase requires a broader tuning range and is thus still the domain of Fourier transform infrared (FTIR) spectroscopy. However, the development of tunable external cavity (EC) QCLs is starting to change this situation. The main advantage of QCLs is their high spectral emission power that is enhanced by a factor of 10(4) compared with thermal light sources. Obviously, transmission measurements with EC-QCLs in strongly absorbing samples are feasible, which can hardly be measured by FTIR due to detector noise limitations. We show that the high power of EC-QCLs facilitates spectroscopy beyond simple absorption measurements. Starting from QCL experiments with liquid samples, we show results of fiber evanescent field analysis (FEFA) to detect pesticides in drinking water. FEFA is a special case of attenuated total reflection spectroscopy. Furthermore, powerful CW EC-QCLs enable fast vibrational circular dichroism (VCD) spectroscopy of chiral molecules in the liquid phase - a technique which is very time consuming with standard FTIR equipment. We present results obtained for the chiral compound 1,1'-bi-2-naphthol (BINOL). Finally, powerful CW EC-QCLs enable the application of laser photothermal emission spectroscopy (LPTES). We demonstrate this for a narrowband and broadband absorber in the gas phase. All three techniques have great potential for MIR process analytical applications.

  4. THE CROP YIELD GAP BETWEEN ORGANIC AND CONVENTIONAL AGRICULTURE%有机—常规农业中作物产量差距分析

    Institute of Scientific and Technical Information of China (English)

    托曼克·德·波帝; 波特·里克; 马丁·克·范·伊特松

    2015-01-01

    to feed the world. Comparisons of organic and conventional yields play a central role in this debate. We therefore compiled and analyzed a meta-dataset of 362 published organ-ic-conventional comparative crop yields. Our results show that organic yields of individual crops are on average 80%of conventional yields,but variation is substantial( standard deviation 21%) . In our dataset,the organic yield gap significantly differed between crop groups and regions. The analysis gave some support to our hypothesis that the or-ganic-conventional yield gap increases as conventional yields increase, but this relationship was only rather weak. The rationale behind this hypothesis is that when conventional yields are high and relatively close to the po-tential or water-limited level,nutrient stress must,as per definition of the potential or water-limited yield levels,be low and pests and diseases well controlled,which are conditions more difficult to attain in organic agriculture. We discuss our findings in the context of the literature on this subject and address the issue of upscaling our results to higher system levels. Our analysis was at field and crop level. We hypothesize that due to challenges in the mainte-nance of nutrient availability in organic systems at crop rotation,farm and regional level,the average yield gap be-tween conventional and organic systems may be larger than 20% at higher system levels. This relates in particular to the role of legumes in the rotation and the farming system,and to the availability of( organic) manure at the farm and regional levels. Future research should therefore focus on assessing the relative performance of both types of agricul-ture at higher system levels,i. e. the farm,regional and global system levels,and should in that context pay particu-lar attention to nutrient availability in both organic and conventional agriculture.

  5. Mapping quantum yield for (Fe-Zn-Sn-Ti)Ox photoabsorbers using a high throughput photoelectrochemical screening system.

    Science.gov (United States)

    Xiang, Chengxiang; Haber, Joel; Marcin, Martin; Mitrovic, Slobodan; Jin, Jian; Gregoire, John M

    2014-03-10

    Combinatorial synthesis and screening of light absorbers are critical to material discoveries for photovoltaic and photoelectrochemical applications. One of the most effective ways to evaluate the energy-conversion properties of a semiconducting light absorber is to form an asymmetric junction and investigate the photogeneration, transport and recombination processes at the semiconductor interface. This standard photoelectrochemical measurement is readily made on a semiconductor sample with a back-side metallic contact (working electrode) and front-side solution contact. In a typical combinatorial material library, each sample shares a common back contact, requiring novel instrumentation to provide spatially resolved and thus sample-resolved measurements. We developed a multiplexing counter electrode with a thin layer assembly, in which a rectifying semiconductor/liquid junction was formed and the short-circuit photocurrent was measured under chopped illumination for each sample in a material library. The multiplexing counter electrode assembly demonstrated a photocurrent sensitivity of sub-10 μA cm(-2) with an external quantum yield sensitivity of 0.5% for each semiconductor sample under a monochromatic ultraviolet illumination source. The combination of cell architecture and multiplexing allows high-throughput modes of operation, including both fast-serial and parallel measurements. To demonstrate the performance of the instrument, the external quantum yields of 1819 different compositions from a pseudoquaternary metal oxide library, (Fe-Zn-Sn-Ti)Ox, at 385 nm were collected in scanning serial mode with a throughput of as fast as 1 s per sample. Preliminary screening results identified a promising ternary composition region centered at Fe0.894Sn0.103Ti0.0034Ox, with an external quantum yield of 6.7% at 385 nm.

  6. Solvent dependence of laser-synthesized blue-emitting Si nanoparticles: Size, quantum yield, and aging performance

    Science.gov (United States)

    Xin, Yunzi; Kitasako, Takumi; Maeda, Makoto; Saitow, Ken-ichi

    2017-04-01

    Pulsed-laser ablation of silicon (Si) was conducted in six different organic solvents using a nanosecond laser. Si nanoparticles (Si-NPs) that exhibited blue photoluminescence (PL) were generated in all the solvents, but a significant solvent dependence emerged: particle size, PL spectra, and PL quantum yield (QY). The results of solvent dependence were well characterized using an atomic ratio in a solvent molecule. The highest QY was observed for the smallest Si-NPs (ca. 2 nm) synthesized in 1-octyne. The QY was enhanced by aging in 1-octyne, and its mechanism was attributed to alkyl passivation of dangling bonds on the Si-NPs.

  7. Quantum molecular dynamics approach to estimate spallation yield from + 208Pb reaction at 800 MeV

    Indian Academy of Sciences (India)

    P K Sarkar; Maitreyee Nandy

    2003-10-01

    The spallation yield of neutrons and other mass fragments produced in 800 MeV proton induced reaction on 208Pb have been calculated in the framework of quantum molecular dynamics (QMD) model. The energy spectra and angular distribution have been calculated. Also, multiplicity distributions of the emitted neutrons and kinetic energy carried away by them have been estimated and compared with the available experimental data. The agreement is satisfactory. A major contribution to the neutron emission comes from statistical decay of the fragments. For mass and charge distributions of spallation productsthe QMD process gives rise to target-like and projectile-like fragments only.

  8. Active and silent chromophore isoforms for phytochrome Pr photoisomerization: An alternative evolutionary strategy to optimize photoreaction quantum yields

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2014-01-01

    Full Text Available Photoisomerization of a protein bound chromophore is the basis of light sensing of many photoreceptors. We tracked Z-to-E photoisomerization of Cph1 phytochrome chromophore PCB in the Pr form in real-time. Two different phycocyanobilin (PCB ground state geometries with different ring D orientations have been identified. The pre-twisted and hydrogen bonded PCBa geometry exhibits a time constant of 30 ps and a quantum yield of photoproduct formation of 29%, about six times slower and ten times higher than that for the non-hydrogen bonded PCBb geometry. This new mechanism of pre-twisting the chromophore by protein-cofactor interaction optimizes yields of slow photoreactions and provides a scaffold for photoreceptor engineering.

  9. The Effects of Controlled Release Fertilizer and Conventional Complex Fertilizer on the Dry Matter Accumulation and the Yield in Winter Wheat

    Directory of Open Access Journals (Sweden)

    Guoqing Li

    2013-03-01

    Full Text Available In order to research the use ratio of controlled release fertilizer in winter wheat. So, the experiment about the effects of Controlled Release Fertilizer (CRF and Conventional Complex Fertilizer (CCF on the dry matter accumulation and the grain yield in winter wheat has studied with pots in the open field. The results indicated that the CRF improved the proportion of the number of effective tillers to the total number of tillers. And the mixture of the CRF and equivalent CCF have more improved the proportion of the dry root weight to the total dry matters of the after of wheat flowering stage than that of the CRF used alone (T1, T2, T3. The treatment T6 was more improved the accumulation of the dry matters of aerial part than others. And the weight gain of T6 after a thesis was higher than other treatments and the control treatment (CK. In the facts of grain number per spike, thousand grain weight and yield, the treatments of the mixture of the CRF and equivalent CCF (T4,T5,T6 were higher than that of the treatments of CRF used only (T1,T2,T3 and CK, in which the T6 was highest. So, we think that this treatment namely T6 was used fertilizers least and gained the highest yield of grain.

  10. [Effects of applying controlled-release fertilizer blended with conventional nitrogen fertilizer on Chinese cabbage yield and quality as well as nitrogen losses].

    Science.gov (United States)

    Yang, Jun-gang; Xu, Kai; Tong, Er-jian; Cao, Bing; Ni, Xiao-hui; Xu, Jun-xiang

    2010-12-01

    An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3- -N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg x hm(-2)) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg x hm(-2)), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg x hm(-2) of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3- -N leaching. At harvest, the NO3- -N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment.

  11. Effects of Cultural System (Organic and Conventional on Growth, Photosynthesis and Yield Components of Sweet Corn (Zea mays L. under Semi-Arid Environment

    Directory of Open Access Journals (Sweden)

    Aspasia EFTHIMIADOU

    2009-11-01

    Full Text Available Organic sweet maize consists of a new industrial crop product. Field experiment was conducted to determine the effects of cultural systems on growth, photosynthesis and yield components of sweet maize crop (Zea mays L. F1 hybrid Midas. A randomized complete block design was employed with four replicates per treatment (organic fertilization: cow manure (5, 10 and 20 t ha1, poultry manure (5, 10 and 20 t ha1 and barley mulch (5, 10 and 20 t ha1, synthetic fertilizer (240 kg N ha1: 21-0-0 and control. The lowest dry weight, height and leaf area index and soil organic matter were measured in the control treatment. Organic matter content was proportionate to the amount of manure applied. The control plots had the lowest yield (1593 kg ha-1 and the double rate cow manure plots the had greatest one. (6104 kg ha-1. High correlation between sweet corn yield and organic matter was registered. Moreover, the lowest values of 1000-grain weight were obtained with control plot. The fertilizer plot gave values, which were similar to the full rate cow manure treatment. The photosynthetic rate of the untreated control was significantly lower than that of the other treatments. The photosynthetic rate increased as poultry manure and barley mulch rates decreased and as cow manure increased. Furthermore, the untreated control had the lowest stomatal conductance and chlorophyll content. Our results indicated that sweet corn growth and yield in the organic plots was significantly higher than those in the conventional plots.

  12. Effects of Bleaching by Nitrogen Deficiency on the Quantum Yield of Photosystem II in Synechocystis sp. PCC 6803 Revealed by Chl Fluorescence Measurements.

    Science.gov (United States)

    Ogawa, Takako; Sonoike, Kintake

    2016-03-01

    Estimation of photosynthesis by Chl fluorescence measurement of cyanobacteria is always problematic due to the interference from respiratory electron transfer and from phycocyanin fluorescence. The interference from respiratory electron transfer could be avoided by the use of DCMU or background illumination by blue light, which oxidizes the plastoquinone pool that tends to be reduced by respiration. On the other hand, the precise estimation of photosynthesis in cells with a different phycobilisome content by Chl fluorescence measurement is difficult. By subtracting the basal fluorescence due to the phycobilisome and PSI, it becomes possible to estimate the precise maximum quantum yield of PSII in cyanobacteria. Estimated basal fluorescence accounted for 60% of the minimum fluorescence, resulting in a large difference between the 'apparent' yield and 'true' yield under high phycocyanin conditions. The calculated value of the 'true' maximum quantum yield of PSII was around 0.8, which was similar to the value observed in land plants. The results suggest that the cause of the apparent low yield reported in cyanobacteria is mainly ascribed to the interference from phycocyanin fluorescence. We also found that the 'true' maximum quantum yield of PSII decreased under nitrogen-deficient conditions, suggesting the impairment of the PSII reaction center, while the 'apparent' maximum quantum yield showed a marginal change under the same conditions. Due to the high contribution of phycocyanin fluorescence in cyanobacteria, it is essential to eliminate the influence of the change in phycocyanin content on Chl fluorescence measurement and to evaluate the 'true' photosynthetic condition.

  13. A comparison of the retention of vitamins B1, B2 and B6, and cooking yield in pork loin with conventional and enhanced meal-service systems

    DEFF Research Database (Denmark)

    Lassen, Anne Dahl; Kall, M.; Hansen, K.;

    2002-01-01

    In this study different simulated meal-service systems were compared with respect to vitamin B-1, B-2 and B-6 retention, and cooking yield in pork roasts. Initially the roasts were cooked traditionally or sous vide. No significant differences were observed between cooking methods. Further...... processing included warm-holding, conventional cook-chill, modified atmosphere packaging (MAP) and sous vide. Compared to retention in the freshly cooked samples, vitamin B-2 retention remained unaffected, irrespective of the meal-service system used and storage period. As regards vitamin B-1 and vitamin B-6......, retentions declined significantly, by 14% and 21% respectively during 3 h of warm-holding, and by 11% and 19% respectively after 1 day of storage and subsequent reheating (cook-chill, MAP and sous vide). Vitamin B-1 retention declined by an extra 4% during storage for 14 days (sous vide) (not significant...

  14. Harnessing Diversity in Wheat to Enhance Grain Yield, Climate Resilience, Disease and Insect Pest Resistance and Nutrition Through Conventional and Modern Breeding Approaches

    Science.gov (United States)

    Mondal, Suchismita; Rutkoski, Jessica E.; Velu, Govindan; Singh, Pawan K.; Crespo-Herrera, Leonardo A.; Guzmán, Carlos; Bhavani, Sridhar; Lan, Caixia; He, Xinyao; Singh, Ravi P.

    2016-01-01

    Current trends in population growth and consumption patterns continue to increase the demand for wheat, a key cereal for global food security. Further, multiple abiotic challenges due to climate change and evolving pathogen and pests pose a major concern for increasing wheat production globally. Triticeae species comprising of primary, secondary, and tertiary gene pools represent a rich source of genetic diversity in wheat. The conventional breeding strategies of direct hybridization, backcrossing and selection have successfully introgressed a number of desirable traits associated with grain yield, adaptation to abiotic stresses, disease resistance, and bio-fortification of wheat varieties. However, it is time consuming to incorporate genes conferring tolerance/resistance to multiple stresses in a single wheat variety by conventional approaches due to limitations in screening methods and the lower probabilities of combining desirable alleles. Efforts on developing innovative breeding strategies, novel tools and utilizing genetic diversity for new genes/alleles are essential to improve productivity, reduce vulnerability to diseases and pests and enhance nutritional quality. New technologies of high-throughput phenotyping, genome sequencing and genomic selection are promising approaches to maximize progeny screening and selection to accelerate the genetic gains in breeding more productive varieties. Use of cisgenic techniques to transfer beneficial alleles and their combinations within related species also offer great promise especially to achieve durable rust resistance. PMID:27458472

  15. Measurement of Quantum Yield, Quantum Requirement, and Energetic Efficiency of the O2-Evolving System of Photosynthesis by a Simple Dye Reaction

    Science.gov (United States)

    Ros Barcelò, A.; Zapata, J. M.

    1996-11-01

    Photosynthesis is the conversion of absorbed radiant energy from sunlight into various forms of chemical energy by the chloroplasts of higher green plants. The overall process of photosynthesis consists of the oxidation of water (with the release of O2 as a product) and the reduction of CO2 to form carbohydrates. In the test tube electrons produced by the photolytic cleavage of H2) may be deviated from their true acceptor by inserting a suitable dye in the electron chain; i.e.; 2,6-dichlorophenol indophenol (DCPIP) (E'o = + 0.217 V), which is blue in the oxidized quinone form and which becomes colorless when reduced to the phenolic form. This dye-electrom acceptor also has the advantage that it accepts electroms directly from the quinone (Qa) electron-acceptor of the photosystem IIsupplied) of the O2-evolving system of photosynthesis. Although values for the quantum yield, the quantum requirement and the energetic efficiency calculated in the classroom laboratory differ widely from those expected theoretically, these calculations are useful for illustrating the transformation of light energy into chemical energy by the chloroplasts of green plants.

  16. In vivo characterization of hair and skin derived carbon quantum dots with high quantum yield as long-term bioprobes in zebrafish

    Science.gov (United States)

    Zhang, Jing-Hui; Niu, Aping; Li, Jing; Fu, Jian-Wei; Xu, Qun; Pei, De-Sheng

    2016-11-01

    Carbon quantum dots (CDs) were widely investigated because of their tunable fluorescence properties and low toxicity. However, so far there have been no reports on in vivo functional studies of hair and skin derived CDs. Here, hair derived CDs (HCDs) and skin derived CDs (SCDs) were produced by using human hair and pig skin as precursors. The quantum yields (QYs) of HCDs and SCDs were quite high, compared to citric acid derived CDs (CCDs). HCDs and SCDs possess optimal photostability, hypotoxicity and biocompatibility in zebrafish, indicating that HCDs and SCDs possess the capacity of being used as fluorescence probes for in vivo biological imaging. The long-time observation for fluorescence alternation of CDs in zebrafish and the quenching assay of CDs by ATP, NADH and Fe3+ ions demonstrated that the decaying process of CDs in vivo might be induced by the synergistic effect of the metabolism process. All results indicated that large batches and high QYs of CDs can be acquired by employing natural and nontoxic hair and skin as precursors. To our knowledge, this is the first time to report SCDs, in vivo comparative studies of HCDs, SCDs and CCDs as bioprobes, and explore their mechanism of photostability in zebrafish.

  17. Iridium Cyclometalated Complexes in Host-Guest Chemistry: A Strategy for Maximizing Quantum Yield in Aqueous Media.

    Science.gov (United States)

    Alrawashdeh, Lubna R; Cronin, Michael P; Woodward, Clifford E; Day, Anthony I; Wallace, Lynne

    2016-07-01

    The weaker emission typically seen for iridium(III) cyclometalated complexes in aqueous medium can be reversed via encapsulation in cucurbit[10]uril (Q[10]). The Q[10] cavity is shown to effectively maximize quantum yields for the complexes, compared to any other medium. This may provide significant advantages for a number of sensor applications. NMR studies show that the complexes are accommodated similarly within the host molecule, even with cationic substituents attached to the ppy ligands, indicating that the hydrophobic effect is the dominant driving force for binding. Cavity-encapsulated 1:1 host-guest species dominate the emission, but 1:2 species are also indicated, which also give some enhancement of intensity. Results demonstrate that the enhancement is due primarily to much lower rates of nonradiative decay but also suggest that the encapsulation can cause a change in character of the emitting state.

  18. Freestanding carbon nanodots/poly (vinyl alcohol) films with high photoluminescent quantum yield realized by inverted-pyramid structure

    Science.gov (United States)

    Pang, Linna; Ba, Lixiang; Pan, Wei; Shen, Wenzhong

    2017-02-01

    Carbon nanodots (C-dots) have attracted great attention for their biocompatibility and strong tunable photoluminescence (PL). However, aggregation-induced PL quenching blocks their practical application in solid-state optoelectronics. Here, we report a luminescent C-dots freestanding film with a substantially enhanced high quantum yield (QY) of 72.3%. A facile template method, rather than complicate lithography and etching technique is proposed to fabricate the C-dots composite films with large-area (8 inch × 8 inch) ordered micro-scale inverted-pyramid patterns on the surface. The control experiment and theoretical analysis demonstrate the key success to QY enhancement lies in the separation of C-dots and the pattern of surface inverted-pyramid structure. This work realizes the QY enhancement simply by geometrical optics, not the chemical treatment of luminescent particles. It provides a general approach to fabricate large-area freestanding luminescent composite film with high QY.

  19. Phosphorescent Iridium(III) Complexes Bearing Fluorinated Aromatic Sulfonyl Group with Nearly Unity Phosphorescent Quantum Yields and Outstanding Electroluminescent Properties.

    Science.gov (United States)

    Zhao, Jiang; Yu, Yue; Yang, Xiaolong; Yan, Xiaogang; Zhang, Huiming; Xu, Xianbin; Zhou, Guijiang; Wu, Zhaoxin; Ren, Yixia; Wong, Wai-Yeung

    2015-11-11

    A series of heteroleptic functional Ir(III) complexes bearing different fluorinated aromatic sulfonyl groups has been synthesized. Their photophysical features, electrochemical behaviors, and electroluminescent (EL) properties have been characterized in detail. These complexes emit intense yellow phosphorescence with exceptionally high quantum yields (ΦP > 0.9) at room temperature, and the emission maxima of these complexes can be finely tuned depending upon the number of the fluorine substituents on the pendant phenyl ring of the sulfonyl group. Furthermore, the electrochemical properties and electron injection/transporting (EI/ET) abilities of these Ir(III) phosphors can also be effectively tuned by the fluorinated aromatic sulfonyl group to furnish some desired characters for enhancing the EL performance. Hence, the maximum luminance efficiency (ηL) of 81.2 cd A(-1), corresponding to power efficiency (ηP) of 64.5 lm W(-1) and external quantum efficiency (ηext) of 19.3%, has been achieved, indicating the great potential of these novel phosphors in the field of organic light-emitting diodes (OLEDs). Furthermore, a clear picture has been drawn for the relationship between their optoelectronic properties and chemical structures. These results should provide important information for developing highly efficient phosphors.

  20. Quality of carcass sides, yield and distribution of certain tissues in carcasses from pigs fattened in conventional way and on deep litter

    Directory of Open Access Journals (Sweden)

    Kosovac Olga

    2008-01-01

    Full Text Available Objective of this research was to present and compare results of the research of the effect of two fattening methods, on deep litter and conventional method (without litter. Slaughter properties have been determined with special focus on distribution of certain tissues in pig carcasses fattened in two different ways. Research was carried out on meat, fattening pig breeds - Swedish landrace. Research included 115 fatteners from single farm in Vojvodina. Depending on the housing conditions, two groups were formed: first group - group I (60 heads in group was housed on deep litter, and the second - group II (55 heads in group, without litter. At the end of the trial, pigs were slaughtered and dissection was performed on cooled (+4ºC left carcass sides and meat yield determined using the method of partial dissection (Walstra and Merkus, 1996. Carcass sides were cut in 12 parts. Based on the meat quantity in four main carcass parts: leg, shoulder, back-loin part (BLP and belly-rib part (BRP, which contain 75% of total musculature mass and mass of tenderloin of carcass side, meat percentage in carcass sides was calculated according to formulation (Manojlović Danica et al., 1999. Fatteners housed on deep litter had statistically significantly (**p<0.01 lower mass of cool carcass sides (38.38 kg compared to fatteners housed without litter (40.90 kg. Higher absolute and relative shares of leg (10.22 kg and 25.02% were established and higher absolute yield of shoulder (5.35 kg in fatteners housed in boxes without litter (II group. Yield of muscle tissue in leg, shoulder, BLP and BRP was higher in fatteners of the II group (without litter compared to pigs fattened on deep litter, and also statistically highly significant differences were established in share of muscle tissue in shoulder (**p<0.01 and considerable differences in regard to share of muscle tissue in BRP (*p<0.05. Meat yield of pig carcass sides was determined by method of partial dissection

  1. Acetylene bridged porphyrin-monophthalocyaninato ytterbium(III) hybrids with strong two-photon absorption and high singlet oxygen quantum yield.

    Science.gov (United States)

    Ke, Hanzhong; Li, Wenbin; Zhang, Tao; Zhu, Xunjin; Tam, Hoi-Lam; Hou, Anxin; Kwong, Daniel W J; Wong, Wai-Kwok

    2012-04-21

    Several acetylene bridged porphyrin-monophthalocyaninato ytterbium(III) hybrids, PZn-PcYb, PH(2)-PcYb and PPd-PcYb, have been prepared and characterized by (1)H and (31)P NMR, mass spectrometry, and UV-vis spectroscopy. Their photophysical and photochemical properties, especially the relative singlet oxygen ((1)O(2)) quantum yields and the two-photon absorption cross-section (σ(2)), were investigated. These three newly synthesized compounds exhibited very large σ(2) values and substantial (1)O(2) quantum yields upon photo-excitation, making them potential candidates as one- and two-photon photodynamic therapeutic agents.

  2. A Novel Method For Predicting Carbon Monoxide Apparent Quantum Yield Spectra in Coastal Water Using Remote Sensing Reflectance Data

    Science.gov (United States)

    Reader, H. E.; Miller, W. L.

    2010-12-01

    Photochemical oxidation of chromophoric dissolved organic matter (CDOM) is the major source of carbon monoxide to the surface ocean. Bacterial consumption and air-sea exchange comprise the two known sinks for CO in marine systems. Though the two loss terms are relatively efficient, CO remains supersaturated with respect to the atmosphere in the surface ocean. Global oceanic estimates of CO photoproduction range from 30-84Tg CO/year (Zafiriou 2003, Fichot and Miller 2010). The variation in estimates is largely due to the difficulty in predicting the efficiency of photoproduction (i.e. Apparent Quantum Yield; AQY). Though the AQY for CO photoproduction appears to be relatively constant, there is indication that terrestrially derived sources, such as those found in estuarine environments, produce CO more efficiently than marine derived sources (Ziolkowski 2000). Since variation among sources is likely in the global ocean, accurate assignment of AQY to variable water types is required to accurately predict CO photoproduction. Deriving the correct apparent quantum yield from remotely sensed data would lead to better predictions of large scale CO photoproduction from optical data. Thirty-eight (38) AQY spectra for CO photoproduction were determined by monthly sampling during spring tides in three dark water locations on the coast of Georgia, USA, from November 2008 to September 2009. Sapelo Sound, a marine dominated system, receives little to no freshwater input over the year, while Altamaha Sound drains the largest watershed in the state of Georgia, and has largely variably freshwater input. Doboy Sound, situated between Sapelo Sound and Altamaha Sound, is largely marine dominated, though in periods of high flow on the Altamaha River, receives some fresh water overflow. The coast of Georgia is dominated by Spartina alterniflora salt marshes, and thus also has a strong non-point source of terrestrially derived carbon. CO apparent quantum yields were determined by

  3. Use of the fluorescence quantum yield for the determination of the number-average molecular weight of polymers of epicatechin with 4β→8 interflavin bonds

    Science.gov (United States)

    D. Cho; W.L. Mattice; L.J. Porter; Richard W. Hemingway

    1989-01-01

    Excitation at 280 nm produces a structureless emission band with a maximum at 321-324 nm for dilute solutions of catechin, epicatechin, and their oligomers in l,4-dioxane or water. The fluorescence quantum yield, Q, has been measured in these two solvents for five dimers, a trimer, a tetramer, a pentamer, a hexamer, and a polymer in which the monomer...

  4. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    Science.gov (United States)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  5. Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield

    KAUST Repository

    Baron, Marco

    2012-02-06

    Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au 2(RIm-Y-ImR) 2](PF 6) 2 (R = Me, Cy; Y = (CH 2) 1-4, o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH 2) 3 exhibit an intense blue emission (λ max = 450 nm) with a high quantum yield (Φ em = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au•••Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au•••Au distance. © 2012 American Chemical Society.

  6. Controls of the quantum yield and saturation light of isoprene emission in different-aged aspen leaves.

    Science.gov (United States)

    Niinemets, Ülo; Sun, Zhihong; Talts, Eero

    2015-12-01

    Leaf age alters the balance between the use of end-product of plastidic isoprenoid synthesis pathway, dimethylallyl diphosphate (DMADP), in prenyltransferase reactions leading to synthesis of pigments of photosynthetic machinery and in isoprene synthesis, but the implications of such changes on environmental responses of isoprene emission have not been studied. Because under light-limited conditions, isoprene emission rate is controlled by DMADP pool size (SDMADP ), shifts in the share of different processes are expected to particularly strongly alter the light dependency of isoprene emission. We examined light responses of isoprene emission in young fully expanded, mature and old non-senescent leaves of hybrid aspen (Populus tremula x P. tremuloides) and estimated in vivo SDMADP and isoprene synthase activity from post-illumination isoprene release. Isoprene emission capacity was 1.5-fold larger in mature than in young and old leaves. The initial quantum yield of isoprene emission (αI ) increased by 2.5-fold with increasing leaf age primarily as the result of increasing SDMADP . The saturating light intensity (QI90 ) decreased by 2.3-fold with increasing leaf age, and this mainly reflected limited light-dependent increase of SDMADP possibly due to feedback inhibition by DMADP. These major age-dependent changes in the shape of the light response need consideration in modelling canopy isoprene emission.

  7. Low cost 3D-printing used in an undergraduate project: an integrating sphere for measurement of photoluminescence quantum yield

    Science.gov (United States)

    Tomes, John J.; Finlayson, Chris E.

    2016-09-01

    We report upon the exploitation of the latest 3D printing technologies to provide low-cost instrumentation solutions, for use in an undergraduate level final-year project. The project addresses prescient research issues in optoelectronics, which would otherwise be inaccessible to such undergraduate student projects. The experimental use of an integrating sphere in conjunction with a desktop spectrometer presents opportunities to use easily handled, low cost materials as a means to illustrate many areas of physics such as spectroscopy, lasers, optics, simple circuits, black body radiation and data gathering. Presented here is a 3rd year undergraduate physics project which developed a low cost (£25) method to manufacture an experimentally accurate integrating sphere by 3D printing. Details are given of both a homemade internal reflectance coating formulated from readily available materials, and a robust instrument calibration method using a tungsten bulb. The instrument is demonstrated to give accurate and reproducible experimental measurements of luminescence quantum yield of various semiconducting fluorophores, in excellent agreement with literature values.

  8. Lyman- photodissociation of CH3CFCl2 (HCFC-141b): Quantum yield and translational energy of hydrogen atoms

    Indian Academy of Sciences (India)

    Almuth Laeuter; Hans-Robert Volpp; Jai P Mittal; Rajesh K Vatsa

    2007-07-01

    The collision-free, room temperature gas-phase photodissociation dynamics of CH3CFCl2 (HCFC-141b) was studied using Lyman- laser radiation (121.6 nm) by the laser photolysis/laserinduced fluorescence `pump/probe’ technique. Lyman- radiation was used both to photodissociate the parent molecule and to detect the nascent H atom products via (22P → 12S) laser-induced fluorescence. Absolute H atom quantum yield, H = (0.39 ± 0.09) was determined by calibration method in which CH4 photolysis at 121.6 nm was used as a reference source of well-defined H atom concentrations. The line shapes of the measured H atom Doppler profiles indicate a Gaussian velocity distribution suggesting the presence of indirect H atom formation pathways in the Lyman- photodissociation of CH3CFCl2. The average kinetic energy of H atoms calculated from Doppler profiles was found to be T(lab) = (50 ± 3) kJ/mol. The nearly statistical translational energy together with the observed Maxwell-Boltzmann velocity distribution indicates that for CH3CFCl2 the H atom forming dissociation process comes closer to the statistical limit.

  9. Action spectrum and maximum quantum yield of carbon fixation in natural phytoplankton populations: implications for primary production estimates in the ocean

    Science.gov (United States)

    Arbones, B.; Figueiras, F. G.; Varela, R.

    2000-09-01

    Spectral and non-spectral measurements of the maximum quantum yield of carbon fixation for natural phytoplankton assemblages were compared in order to evaluate their effect on bio-optical models of primary production. Field samples were collected from two different coastal regions of NW Spain in spring, summer and autumn and in a polar environment (Gerlache Strait, Antarctica) during the austral summer. Concurrent determinations were made of spectral phytoplankton absorption coefficient [ aph( λ)], white-light-limited slope of the photosynthesis-irradiance relationships ( αB), carbon uptake action spectra [ αB( λ)], broad-band maximum quantum yields ( φm), and spectral maximum quantum yields [ φm( λ)]. Carbon uptake action spectra roughly followed the shape of the corresponding phytoplankton absorption spectra but with a slight displacement in the blue-green region that could be attributed to imbalance between the two photosystems PS I and PS II. Results also confirmed previous observations of wavelength dependency of maximum quantum yield. The broad-band maximum quantum yield ( φm) calculated considering the measured spectral phytoplankton absorption coefficient and the spectrum of the light source of the incubators was not significantly different form the averaged spectral maximum quantum yield [ overlineφ max(λ) ] ( t-test for paired samples, P=0.34). These results suggest that maximum quantum yield can be estimated with enough accuracy from white-light P- E curves and measured phytoplankton absorption spectra. Primary production at light limiting regimes was compared using four different models with a varying degree of spectral complexity. No significant differences ( t-test for paired samples, P=0.91) were found between a spectral model based on the carbon uptake action spectra [ αB( λ) — model a] and a model which uses the broad-band φm and measured aph( λ) (model b). In addition, primary production derived from constructed action spectra [ ac

  10. Determinism and Dissipation in Quantum Gravity

    NARCIS (Netherlands)

    Hooft, G. 't

    2001-01-01

    Without invalidating quantum mechanics as a principle underlying the dynamics of a fundamental theory, it is possible to ask for even more basic dynamical laws that may yield quantum mechanics as the machinery needed for its statistical analysis. In conventional systems such as the Standard Model

  11. Cupriphication of gold to sensitize d(10)-d(10) metal-metal bonds and near-unity phosphorescence quantum yields.

    Science.gov (United States)

    Galassi, Rossana; Ghimire, Mukunda M; Otten, Brooke M; Ricci, Simone; McDougald, Roy N; Almotawa, Ruaa M; Alhmoud, Dieaa; Ivy, Joshua F; Rawashdeh, Abdel-Monem M; Nesterov, Vladimir N; Reinheimer, Eric W; Daniels, Lee M; Burini, Alfredo; Omary, Mohammad A

    2017-06-27

    Outer-shell s(0)/p(0) orbital mixing with d(10) orbitals and symmetry reduction upon cupriphication of cyclic trinuclear trigonal-planar gold(I) complexes are found to sensitize ground-state Cu(I)-Au(I) covalent bonds and near-unity phosphorescence quantum yields. Heterobimetallic Au4Cu2 {[Au4(μ-C(2),N(3)-EtIm)4Cu2(µ-3,5-(CF3)2Pz)2], (4a)}, Au2Cu {[Au2(μ-C(2),N(3)-BzIm)2Cu(µ-3,5-(CF3)2Pz)], (1) and [Au2(μ-C(2),N(3)-MeIm)2Cu(µ-3,5-(CF3)2Pz)], (3a)}, AuCu2 {[Au(μ-C(2),N(3)-MeIm)Cu2(µ-3,5-(CF3)2Pz)2], (3b) and [Au(μ-C(2),N(3)-EtIm)Cu2(µ-3,5-(CF3)2Pz)2], (4b)} and stacked Au3/Cu3 {[Au(μ-C(2),N(3)-BzIm)]3[Cu(µ-3,5-(CF3)2Pz)]3, (2)} form upon reacting Au3 {[Au(μ-C(2),N(3)-(N-R)Im)]3 ((N-R)Im = imidazolate; R = benzyl/methyl/ethyl = BzIm/MeIm/EtIm)} with Cu3 {[Cu(μ-3,5-(CF3)2Pz)]3 (3,5-(CF3)2Pz = 3,5-bis(trifluoromethyl)pyrazolate)}. The crystal structures of 1 and 3a reveal stair-step infinite chains whereby adjacent dimer-of-trimer units are noncovalently packed via two Au(I)⋯Cu(I) metallophilic interactions, whereas 4a exhibits a hexanuclear cluster structure wherein two monomer-of-trimer units are linked by a genuine d(10)-d(10) polar-covalent bond with ligand-unassisted Cu(I)-Au(I) distances of 2.8750(8) Å each-the shortest such an intermolecular distance ever reported between any two d(10) centers so as to deem it a "metal-metal bond" vis-à-vis "metallophilic interaction." Density-functional calculations estimate 35-43 kcal/mol binding energy, akin to typical M-M single-bond energies. Congruently, FTIR spectra of 4a show multiple far-IR bands within 65-200 cm(-1), assignable to vCu-Au as validated by both the Harvey-Gray method of crystallographic-distance-to-force-constant correlation and dispersive density functional theory computations. Notably, the heterobimetallic complexes herein exhibit photophysical properties that are favorable to those for their homometallic congeners, due to threefold-to-twofold symmetry reduction, resulting in

  12. Aqueous synthesis of MPA-capped CdTe nanocrystals emitted in near infrared with high quantum yield.

    Science.gov (United States)

    Cao, Yongqiang; Liu, Ning; Yang, Ping; Zhu, Yuanna; Shi, Ruixia; Ma, Qian; Zhang, Aiyu

    2014-07-01

    The high luminescent near infrared (NIR)--emitting CdTe nanocrystals (NCs) with 3-mercaptopropionic acid (MPA) as the stabilized molecules had been sucessfully fabricated by a facile and simple water-reflux method. By virtue of the characterizations for the as-prepared MPA-capped CdTe NCs, such as UV-Vis absorption, steady-state photoluminescence (PL), time-resolved PL spectra and PL image, the optical properties, diameters and morphologies of the CdTe NCs were investigated detailedly. With the increase of reflux time, the PL peak wavelength of NCs gradually shifted from red light to NIR spectra range within 7 h, and the PL quantum yield (QY) was increased firstly and then decreased slightly. It was worth noted that the NCs still showed a relative high PL QY of 47% as well as a narrow full width at half maximum (FWHM) of PL spectra even when the NCs emitted at the NIR wavelength of 754 nm. In addition, the average PL lifetime also exhibited an obvious increase as the growth of CdTe NCs due to the formation of thin CdS shell on the surface of CdTe. The PL stabilities for these NIR-emitting NCs (754 nm) in phosphate-buffered saline (PBS) buffer solution with various concentrations ranged from 0.005 to 0.1 M were also checked accordingly, and the results indicated that the as-prepared NIR-emitting CdTe NCs had a satisfied PL stability, implying a potential application in the biological field. Hopefully, all the superiority of these NIR-emitting CdTe NCs, such as high PL QY and PL lifetime, narrow FWHM of PL spectra, high PL stability in PBS solution, would make them to be a good candidate for biological applications in future.

  13. A 200-fold quantum yield boost in the photoluminescence of silver-doped Ag(x)Au(25-x) nanoclusters: the 13th silver atom matters.

    Science.gov (United States)

    Wang, Shuxin; Meng, Xiangming; Das, Anindita; Li, Tao; Song, Yongbo; Cao, Tiantian; Zhu, Xiuyi; Zhu, Manzhou; Jin, Rongchao

    2014-02-24

    The rod-shaped Au25 nanocluster possesses a low photoluminescence quantum yield (QY=0.1%) and hence is not of practical use in bioimaging and related applications. Herein, we show that substituting silver atoms for gold in the 25-atom matrix can drastically enhance the photoluminescence. The obtained Ag(x)Au(25-x) (x=1-13) nanoclusters exhibit high quantum yield (QY=40.1%), which is in striking contrast with the normally weakly luminescent Ag(x)Au(25-x) species (x=1-12, QY=0.21%). X-ray crystallography further determines the substitution sites of Ag atoms in the Ag(x)Au(25-x) cluster through partial occupancy analysis, which provides further insight into the mechanism of photoluminescence enhancement. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Accurate quantum yields by laser gain vs absorption spectroscopy - Investigation of Br/Br(asterisk) channels in photofragmentation of Br2 and IBr

    Science.gov (United States)

    Haugen, H. K.; Weitz, E.; Leone, S. R.

    1985-01-01

    Various techniques have been used to study photodissociation dynamics of the halogens and interhalogens. The quantum yields obtained by these techniques differ widely. The present investigation is concerned with a qualitatively new approach for obtaining highly accurate quantum yields for electronically excited states. This approach makes it possible to obtain an accuracy of 1 percent to 3 percent. It is shown that measurement of the initial transient gain/absorption vs the final absorption in a single time-resolved signal is a very accurate technique in the study of absolute branching fractions in photodissociation. The new technique is found to be insensitive to pulse and probe laser characteristics, molecular absorption cross sections, and absolute precursor density.

  15. Electron Photodetachment from Aqueous Anions. I. Quantum Yields for Generation of Hydrated Electron by 193 and 248 nm Laser Photoexcitation of Miscellaneous Inorganic Anions

    CERN Document Server

    Sauer, M C; Shkrob, I A; Sauer, Myran C.; Shkrob, Ilya A.

    2004-01-01

    Time resolved transient absorption spectroscopy has been used to determine quantum yields for electron photodetachment in 193 nm and (where possible) 248 nm laser excitation of miscellaneous aqueous anions, including hexacyanoferrate(II), sulfate, sulfite, halide anions (Cl-, Br-, and I-), pseudohalide anions (OH-, HS-, CNS-), and several common inorganic anions for which no quantum yields have been reported heretofore: SO3=, NO2-, NO3-, ClO3- and ClO4-. Molar extinction coefficients for these anions and photoproducts of electron detachment from these anions at the excitation wavelengths were also determined. These results are discussed in the context of recent ultrafast kinetic studies and compared with the previous data obtained by product analyses. We suggest using electron photodetachment from the aqueous halide and pseudohalide anions as actinometric standard for time-resolved studies of aqueous photosystems in the UV.

  16. Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

    Energy Technology Data Exchange (ETDEWEB)

    Diroll, Benjamin T.; Talapin, Dmitri V.; Schaller, Richard D.

    2017-02-13

    Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS and newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields of 2% or less for single excitons, which we show results from hole trapping, the samples exhibit low ASE thresholds. Furthermore, four-monolayer CdS samples show ASE at shorter wavelengths than any reported film of colloidal quantum-confined material. This work underlines that low quantum yields for single excitons do not necessarily lead to a poor gain medium. The low ASE thresholds originate from negligible dispersion in thickness, large absorption cross sections of 2.8 × 10–14 cm–2, and rather slow (150 to 300 ps) biexciton recombination. We show that under higher-fluence excitation, ASE can kinetically outcompete hole trapping. Using nanoplatelets as the gain medium, lasing is observed in a linear optical cavity. This work confirms the fundamental advantages of colloidal quantum well structures as gain media, even in the absence of high photoluminescence efficiency.

  17. Quantum yield for O-atom production in the VUV photodissociation of CO2 using the time-sliced velocity-mapped imaging (TS-VMI) method

    Science.gov (United States)

    Jackson, William M.

    2016-10-01

    VUV photodissociation above 10.5 eV is considered the primary region for photochemical destruction of CO2 by solar radiation. There is enough photon energy in this region so that in addition to ground state O(3PJ) and CO(1Σ +) that can be produced during photodissociation excited species such as atomic oxygen O(1D) and O(1S), as well as excited carbon monoxide CO(a3Π, a'3Σ+) also can be formed. Electronic excited oxygen atom and carbon monoxide are the species that are responsible for the airglows in atmospheres of the solar planets and comets. Therefore, detail photodissociation quantum yields for these excited species from CO2 are critical in interpreting the chemistry in these solar system bodies. We have previously shown that the time-sliced velocity-mapped imaging (TS-VMI) technique can provide detailed branching ratio information about photodissociation of diatomic molecules.1, 2 However, to date we have not been able to show how this technique can be use to determine absolute quantum yields for the products produced in the VUV photodissociation of CO2. In this talk we will describe how the known quantum yields for the photodissociation O2 to O(3P2), O(3P1), O(3P0) and O(1D) can be used to determine quantum yields of similar products in the photodissociation of CO2.[1] Yu Song, Hong Gao, Yih Chung Chang, D. Hammouténe, H. Ndome, M. Hochlaf, William M. Jackson, and C. Y. Ng, Ap. J., 819:23 (13pp), 2016; doi:10.3847/0004-637X/819/1/23.[2] Hong Gao, Yu Song, William M. Jackson and C. Y. Ng, J. Chem. Phys, 138, 191102, 2013.

  18. Fluorescence quantum yields of natural organic matter and organic compounds: Implications for the fluorescence-based interpretation of organic matter composition

    DEFF Research Database (Denmark)

    Wünsch, Urban; Murphy, Kathleen R.; Stedmon, Colin

    2015-01-01

    Absorbance and fluorescence spectroscopy are economical tools for tracing the supply, turnover and fate of dissolved organic matter (DOM). The colored and fluorescent fractions of DOM (CDOM and FDOM, respectively) are linked by the apparent fluorescence quantum yield (AQY) of DOM, which reflects ...... to confirm matches was limited due to multiple compounds exhibiting very similar spectra. This reiterates the fact that spectral similarity alone is insufficient evidence of the presence of particular compounds, and additional evidence is required...

  19. Increased upconversion quantum yield in photonic structures due to local field enhancement and modification of the local density of states--a simulation-based analysis.

    Science.gov (United States)

    Herter, Barbara; Wolf, Sebastian; Fischer, Stefan; Gutmann, Johannes; Bläsi, Benedikt; Goldschmidt, Jan Christoph

    2013-09-09

    In upconversion processes, two or more low-energy photons are converted into one higher-energy photon. Besides other applications, upconversion has the potential to decrease sub-band-gap losses in silicon solar cells. Unfortunately, upconverting materials known today show quantum yields, which are too low for this application. In order to improve the upconversion quantum yield, two parameters can be tuned using photonic structures: first, the irradiance can be increased within the structure. This is beneficial, as upconversion is a non-linear process. Second, the rates of the radiative transitions between ionic states within the upconverter material can be altered due to a varied local density of photonic states. In this paper, we present a theoretical model of the impact of a photonic structure on upconversion and test this model in a simulation based analysis of the upconverter material β -NaYF(4):20% Er(3+) within a dielectric waveguide structure. The simulation combines a finite-difference time-domain simulation model that describes the variations of the irradiance and the change of the local density of photonic states within a photonic structure, with a rate equation model of the upconversion processes. We find that averaged over the investigated structure the upconversion luminescence is increased by a factor of 3.3, and the upconversion quantum yield can be improved in average by a factor of 1.8 compared to the case without the structure for an initial irradiance of 200 Wm(-2).

  20. Absolute quantum yield measurements for the formation of oxygen atoms after UV laser excitation of SO2 at 222.4 nm

    Indian Academy of Sciences (India)

    Mohammed Abu-Bajeh; Melanie Cameron; Kyung-Hoon Jung; Christoph Kappel; Almuth Läuter; Kyoung-Seok Lee; Hari P Upadhyaya; Rajesh K Vatsa; Hans-Robert Volpp

    2002-12-01

    The dynamics of formation of oxygen atoms after UV photoexcitation of SO2 in the gas-phase was studied by pulsed laser photolysis-laser-induced fluorescence `pump-and-probe' technique in a flow reactor. SO2 at room-temperature was excited at the KrCl excimer laser wavelength (222.4 nm) and O(3P) photofragments were detected under collision-free conditions by vacuum ultraviolet laser-induced fluorescence. The use of narrow-band probe laser radiation, generated via resonant third-order sum-difference frequency conversion of dye laser radiation in Krypton, allowed the measurement of the nascent O(3P=2,1,0) fine-structure state distribution: =2/=1/=0 = (0.88 ± 0.02)/(0.10 ± 0.01)/(0.02 ± 0.01). Employing NO2 photolysis as a reference, a value of O(3P) = 0.13 ± 0.05 for the absolute O(3P) atom quantum yield was determined. The measured O(3P) quantum yield is compared with the results of earlier fluorescence quantum yield measurements. A suitable mechanism is suggested in which the dissociation proceeds via internal conversion from high rotational states of the initially excited SO2(∼ 1 B2) (1, 2, 2) vibronic level to nearby continuum states of the electronic ground state.

  1. Molar Absorptivity and Quantum Yield of Fe(II) Photo-formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Comlexes

    Science.gov (United States)

    Hitomi, Y.; Arakaki, T.

    2009-04-01

    Fe(III)/Fe(II) cycle in the environment affects formation of active oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be an important source of photo-chemically formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species in the aqueous solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. Dicarboxylate compounds studied were oxalate, malonate, succinate, malate, and phthalate.

  2. Cocoa and total system yields of organic and conventional agroforestry vs. monoculture systems in a long-term field trial in Bolivia

    OpenAIRE

    Schneider, M; Andres, C; Trujillo, G.; Alcon, F.; Amurrios, P.; Perez, E.; Weibel, F.; Milz, J.

    2016-01-01

    Cocoa (Theobroma cacao L.) is produced in systems of varying complexity ranging from monoculture with temporary shade to highly diverse agroforests. Producers have to weigh high cocoa yields in the short to medium term in monocultures against higher total system yields in the short term and sustainable production systems in the long term in conjunction with ecosystem services in agroforestry systems (AFs). More long-term data on the comparative agronomic, economic and ecological performance o...

  3. Grass pea (Lthyrus sativum L.) as pre-plant organic fertilizer for conventionally tilled winter wheat: effects on yield and quality

    Science.gov (United States)

    Sources of organic nitrogen (N) for the southern Great Plains (SGP) - and methods of their use – need testing to find ways to counter the rising cost of N fertilizer. This study investigated the cool-season pulse grass pea (Lathyrus sativum L.) (GP) as a pre-plant N source for continuous, convention...

  4. Assessment of Total Phenolic and Flavonoid Content, Antioxidant Properties, and Yield of Aeroponically and Conventionally Grown Leafy Vegetables and Fruit Crops: A Comparative Study

    Science.gov (United States)

    Chandra, Suman; Khan, Shabana; Avula, Bharathi; Lata, Hemant; Yang, Min Hye; ElSohly, Mahmoud A.; Khan, Ikhlas A.

    2014-01-01

    A comparison of the product yield, total phenolics, total flavonoids, and antioxidant properties was done in different leafy vegetables/herbs (basil, chard, parsley, and red kale) and fruit crops (bell pepper, cherry tomatoes, cucumber, and squash) grown in aeroponic growing systems (AG) and in the field (FG). An average increase of about 19%, 8%, 65%, 21%, 53%, 35%, 7%, and 50% in the yield was recorded for basil, chard, red kale, parsley, bell pepper, cherry tomatoes, cucumber, and squash, respectively, when grown in aeroponic systems, compared to that grown in the soil. Antioxidant properties of AG and FG crops were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DDPH) and cellular antioxidant (CAA) assays. In general, the study shows that the plants grown in the aeroponic system had a higher yield and comparable phenolics, flavonoids, and antioxidant properties as compared to those grown in the soil. PMID:24782905

  5. Photolysis of CF3CH2CHO in the presence of O2 at 248 and 266 nm: quantum yields, products, and mechanism.

    Science.gov (United States)

    Antiñolo, M; Bettinelli, C; Jain, C; Dréan, P; Lemoine, B; Albaladejo, J; Jiménez, E; Fittschen, C

    2013-10-17

    Three different detection techniques, coupled to pulsed laser photolysis (PLP), have been employed to determine the quantum yields of CF3CH2CHO at 248 and 266 nm: CF3CH2CHO + hν → CF3CH2 + HCO (R1a), CF3CH2CHO + hν → CF3CH3 + CO (R1b), and CF3CH2CHO + hν → CF3CH2O + H (R1c). (a) In the presence of air, Fourier transform infrared (FTIR) spectroscopy was employed at a total pressure of 760 Torr to monitor and quantify the loss of CF3CH2CHO at both wavelengths as well as the build-up of formed products (CO, CF3CH3, CF3CHO, and CF3CH2OH) after various laser pulses. Cyclohexane was added as OH-scavenger in most experiments. CF3CH3 was observed and quantified at both wavelengths, confirming that channel R1b is occurring. Small amounts of HCOOH and COF2 were also detected. (b) Time-resolved cw-cavity ring down spectroscopy (cw-CRDS) at 40 Torr He coupled to photolysis at 248 nm was employed for the detection of HO2 radicals. Varying the O2 concentration allows distinguishing the origin of the HO2 radicals from either R1a or R1c. OH radicals were simultaneously detected by laser-induced fluorescence. (c) Time-resolved tunable diode laser absorption spectroscopy (TDLAS) at 30 Torr N2 coupled to photolysis at 266 nm was employed for the determination of the quantum yields of CO. By varying the O2 concentration, a distinction can be achieved between the yields of prompt CO R1b or decomposition of highly excited CF3CH2CO from R1c and HCO radicals R1a. Channel R1a has been identified as the major reaction path. The overall quantum yield, Φλ(CF3CH2CHO), at 248 nm was found as Φ248nm = (0.76 ± 0.14) and (0.73 ± 0.20) from cw-CRDS and FTIR experiments, respectively. At 266 nm, the overall quantum yield was found as Φ266nm = (0.55 ± 0.10) and (0.47 ± 0.10) from TDLAS and FTIR experiments, respectively.

  6. Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network.

    Science.gov (United States)

    Goto, Hayato

    2016-02-22

    The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schrödinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence.

  7. Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network

    Science.gov (United States)

    Goto, Hayato

    2016-02-01

    The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schrödinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence.

  8. Quantum

    CERN Document Server

    Al-Khalili, Jim

    2003-01-01

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

  9. Comparative conventional- and quantum dot-labelling strategies for LPS binding site detection in Arabidopsis thaliana mesophyll protoplasts

    Directory of Open Access Journals (Sweden)

    Londiwe Siphephise Mgcina

    2015-05-01

    Full Text Available Lipopolysaccharide (LPS from Gram-negative bacteria is recognized as a microbe-associated molecular pattern (MAMP and not only induces an innate immune response in plants, but also stimulates the development of characteristic defense responses. However, identification and characterization of a cell surface LPS-receptor/binding site, as described in mammals, remains elusive in plants. As an amphiphilic, macromolecular lipoglycan, intact LPS potentially contains three MAMP-active regions, represented by the O-polysaccharide chain, the core and the lipid A. Binding site studies with intact labelled LPS were conducted in Arabidopsis thaliana protoplasts and quantified using flow cytometry fluorescence changes. Qdots, which allow non-covalent, hydrophobic labelling were used as a novel strategy in this study and compared to covalent, hydrophilic labelling with Alexa 488. Affinity for LPS-binding sites was clearly demonstrated by concentration-, temperature- and time-dependent increases in protoplast fluorescence following treatment with the labelled LPS. Moreover, this induced fluorescence increase was convincingly reduced following pre-treatment with excess unlabeled LPS, thereby indicating reversibility of LPS binding. Inhibition of the binding process is also reported using endo- and exocytosis inhibitors. Here, we present evidence for the anticipated presence of LPS-specific binding sites in Arabidopsis protoplasts, and furthermore propose Qdots as a more sensitive LPS-labelling strategy in comparison to the conventional Alexa 488 hydrazide label for binding studies.

  10. Formation and properties of epitaxial CdSe, ZnSe quantum dots. Conventional molecular beam epitaxy and related techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, Suddhasatta

    2008-01-16

    This thesis systematically investigates three such alternative approaches, along with conventional MBE, with emphasis on the formation-mechanism of QDs, and optimization of their morphological and optical attributes. it is shown here that no distinct 3D islands are formed in MBE growth of CdSe on ZnSe. While CdSe heteroepitaxy occurs in the multilayer-mode at T{sub G}=300 C, a reentrant recovery of the layer-by-layer mode is reported in this thesis, for growth at T{sub G}<{proportional_to}240 C. In the second variant technique, formation of large and distinct islands is demonstrated by deposition of amorphous selenium (a-Se) onto a 2D CdSe epilayer at room temperature and its subsequent desorption at a higher temperature (T{sub D}=230 C). The process steps of the third variant technique, developed in course of this work, are very similar to those of the previous one-the only alteration being the substitution of selenium with tellurium as the cap-forming-material. (orig.)

  11. Probing the charged Higgs quantum numbers through the decay H{sup +}{sub {alpha}} {yields} W{sup +}h{sup 0}{sub s}s

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Cruz, J L [Cuerpo Academico de PartIculas, Campos y Relatividad de la BUAP (Mexico); Felix-Beltran, O [Instituto de Fisica, UNAM, Apdo. Postal 20-364, Mexico 01000 D.F. (Mexico); Hernandez-Sanchez, J [Universidad Autonoma del Estado de Hidalgo, Carretera a Pachuca Tulancingo Km. 4.5, C. U., C.P. 42020, Pachuca Hidalgo (Mexico); Barradas-Guevara, E [Cuerpo Academico de PartIculas, Campos y Relatividad de la BUAP (Mexico)

    2006-05-15

    The vertex H{sup +}{sub {alpha}} {yields} W{sup -}h{sup 0}{sub s}s, involving the gauge boson W{sup {+-}} and the charged (H{sup {+-}}{sub {alpha}}) and neutral Higgs bosons (h{sup 0}{sub s}s), arises within the context of many extensions of the SM, and it can be used to probe the quantum numbers of the Higgs multiplet. After presenting a general discussion for the expected form of this vertex for arbitrary Higgs representations, we discuss its strength for an extended MSSM with one complex triplet. We find that in this model, there are regions of parameters where the decay H{sup +}{sub {alpha}} {yields} W{sup +}h{sup 0}{sub s}s, is kinematically allowed, and reaches Branching Ratios (BR) that may be detectable, thus allowing to test the properties of the Higgs sector.

  12. Upconversion in a Bragg structure: photonic effects of a modified local density of states and irradiance on luminescence and upconversion quantum yield.

    Science.gov (United States)

    Hofmann, Clarissa L M; Herter, Barbara; Fischer, Stefan; Gutmann, Johannes; Goldschmidt, Jan Christoph

    2016-06-27

    In this paper, we present a comprehensive simulation-based analysis of the two photonic effects of a Bragg stack - a modified local density of photon states (LDOS) and an enhanced local irradiance - on the upconversion (UC) luminescence and quantum yield of the upconverter β-NaYF4 doped with 25% Er3+. The investigated Bragg stack consists of alternating layers of TiO2 and Poly(methylmethacrylate), the latter containing upconverter nanoparticles. Using experimentally determined input parameters, the photonic effects are first simulated separately and subsequently coupled in a rate equation model, describing the dynamics of the UC processes within β-NaYF4:25% Er3+. With this integrated simulation model, the Bragg stack design is optimized to maximize either the UC quantum yield (UCQY) or UC luminescence. We find that in an optimized Bragg stack, due to the modified LDOS, the maximum UCQY is enhanced from 14% to 16%, compared to an unstructured layer of upconverter material. Additionally, this maximum UCQY can already be reached at an incident irradiance as low as 100 W/m2. With a Bragg stack design that maximizes UC luminescence, enhancement factors of up to 480 of the UC luminescence can be reached.

  13. Intrinsic Time Quantum Gravity

    CERN Document Server

    Yu, Hoi Lai

    2016-01-01

    Correct identification of the true gauge symmetry of General Relativity being 3d spatial diffeomorphism invariant(3dDI) (not the conventional infinite tensor product group with principle fibre bundle structure), together with intrinsic time extracted from clean decomposition of the canonical structure yields a self-consistent theory of quantum gravity. A new set of fundamental commutation relations is also presented. The basic variables are the eight components of the unimodular part of the spatial dreibein and eight SU(3) generators which correspond to Klauder's momentric variables that characterize a free theory of quantum gravity. The commutation relations are not canonical, but have well defined group theoretical meanings. All fundamental entities are dimensionless; and the quantum wave functionals are preferentially in the dreibein representation. The successful quantum theory of gravity involves only broad spectrum of knowledge and deep insights but no exotic idea.

  14. Quantum yield measurements of short-lived photoactivation intermediates in DNA photolyase: toward a detailed understanding of the triple tryptophan electron transfer chain.

    Science.gov (United States)

    Byrdin, Martin; Lukacs, Andras; Thiagarajan, Viruthachalam; Eker, André P M; Brettel, Klaus; Vos, Marten H

    2010-03-11

    The light-dependent DNA repair enzyme photolyase contains a unique evolutionary conserved triple tryptophan electron transfer chain (W382-W359-W306 in photolyase from E. coli) that bridges the approximately 15 A distance between the buried flavin adenine dinucleotide (FAD) cofactor and the surface of the protein. Upon excitation of the semireduced flavin (FADH(o)), electron transfer through the chain leads to formation of fully reduced flavin (FADH(-); required for DNA repair) and oxidation of the most remote tryptophan residue W306, followed by its deprotonation. The thus-formed tryptophanyl radical W306(o)(+) is reduced either by an extrinsic reductant or by reverse electron transfer from FADH(-). Altogether the kinetics of these charge transfer reactions span 10 orders of magnitude, from a few picoseconds to tens of milliseconds. We investigated electron transfer processes in the picosecond-nanosecond time window bridging the time domains covered by ultrafast pump-probe and "classical" continuous probe techniques. Using a recent dedicated setup, we directly show that virtually no absorption change between 300 ps and 10 ns occurs in wild-type photolyase, implying that no charge recombination takes place in this time window. In contrast, W306F mutant photolyase showed a partial absorption recovery with a time constant of 0.85 ns. In wild-type photolyase, the quantum yield of FADH(-) W306(o)(+) was found at 19 +/- 4%, in reference to the established quantum yield of the long-lived excited state of [Ru(bpy)(3)](2+). With this yield, the optical spectrum of the excited state of FADH(o) can be constructed from ultrafast spectroscopic data; this spectrum is dominated by excited state absorption extending from below 450 to 850 nm. The new experimental results, taken together with previous data, allow us to propose a detailed kinetic and energetic scheme of the electron transfer chain.

  15. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    1998-01-01

    Full Text Available The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii A derivation of the Bekenstein-Hawking black hole entropy formula. (iii An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  16. Past Quantum States of a Monitored System

    DEFF Research Database (Denmark)

    Gammelmark, Søren; Julsgaard, Brian; Mølmer, Klaus

    2013-01-01

    A density matrix ρ(t) yields probabilistic information about the outcome of measurements on a quantum system. We introduce here the past quantum state, which, at time T, accounts for the state of a quantum system at earlier times tstate Ξ(t) is composed of two objects, ρ......(t) and E(t), conditioned on the dynamics and the probing of the system until t and in the time interval [t, T], respectively. The past quantum state is characterized by its ability to make better predictions for the unknown outcome of any measurement at t than the conventional quantum state at that time....... On the one hand, our formalism shows how smoothing procedures for estimation of past classical signals by a quantum probe [M. Tsang, Phys. Rev. Lett. 102 250403 (2009)] apply also to describe the past state of the quantum system itself. On the other hand, it generalizes theories of pre- and postselected...

  17. Oxalyl chloride, ClC(O)C(O)Cl: UV/vis spectrum and Cl atom photolysis quantum yields at 193, 248, and 351 nm.

    Science.gov (United States)

    Ghosh, Buddhadeb; Papanastasiou, Dimitrios K; Burkholder, James B

    2012-10-28

    Oxalyl chloride, (ClCO)(2), has been used as a Cl atom photolytic precursor in numerous laboratory kinetic and photochemical studies. In this study, the UV/vis absorption spectrum of (ClCO)(2) and the Cl atom quantum yields in its photolysis at 193, 248, and 351 nm are reported. The UV∕vis spectrum was measured between 200 and 450 nm at 296 K using diode array spectroscopy in conjunction with an absolute cross section obtained at 213.9 nm. Our results are in agreement with the spectrum reported by Baklanov and Krasnoperov [J. Phys. Chem. A 105, 97-103 (2001)], which was obtained at 11 discrete wavelengths between 193.3 and 390 nm. Cl atom quantum yields, Φ(λ), were measured using pulsed laser photolysis coupled with time resolved atomic resonance fluorescence detection of Cl. The UV photolysis of (ClCO)(2) has been shown in previous studies to occur via an impulsive three-body dissociation mechanism, (COCl)(2) + hv → ClCO* + Cl + CO (2), where the excited ClCO radical, ClCO*, either dissociates or stabilizes ClCO* → Cl + CO (3a), → ClCO (3b). ClCO is thermally unstable at the temperatures (253-298 K) and total pressures (13-128 Torr) used in our experiments ClCO + M → Cl + CO + M (4) leading to the formation of a secondary Cl atom that was resolvable in the Cl atom temporal profiles obtained in the 248 and 351 nm photolysis of (ClCO)(2). Φ(193 nm) was found to be 2.07 ± 0.37 independent of bath gas pressure (25.8-105.7 Torr, N(2)), i.e., the branching ratio for channel 2a or the direct formation of 2Cl + 2CO in the photolysis of (ClCO)(2) is >0.95. At 248 nm, the branching ratio for channel 2a was determined to be 0.79 ± 0.15, while the total Cl atom yield, i.e., following the completion of reaction (4), was found to be 1.98 ± 0.26 independent of bath gas pressure (15-70 Torr, N(2)). Φ(351 nm) was found to be pressure dependent between 7.8 and 122.4 Torr (He, N(2)). The low-pressure limit of the total Cl atom quantum yield, Φ(0)(351 nm), was 2

  18. Structural and physicochemical aspects of silica encapsulated ZnO quantum dots with high quantum yield and their natural uptake in HeLa cells.

    Science.gov (United States)

    Depan, D; Misra, R D K

    2014-09-01

    Photoluminescent semiconductor quantum dots (QDs) are of significant interest for bioimaging and fluorescence labeling. In this regard, we describe here the design of high sensitivity and high specificity non-toxic ZnO QDs (∼5 nm) with long-term stability of up to 12 months. The embedding of ZnO QDs on silica nanospheres led to significant increase in photoluminescence intensity rendering them highly bright QD-based probes. The QDs were characterized in vitro with respect to cancer cells (HeLa) and evaluated in terms of viability, fluorescence and cytoskeletal organization. The immobilization of ZnO QDs on silica nanospheres promoted the internalization and enhanced fluorescence emission of HeLa cells. The fluorescence emission from QDs was stable for 3 days, indicating excellent stability toward photobleaching. Cytoskeletal reorganization was observed after internalization of QDs such that the ZnO QDS on silica nanospheres resulted in broadening of the actin cytoskeleton. The study underscores that ZnO QDs immobilized on Si nanospheres are promising for tracking cancer cells in cell therapy.

  19. Improved photoluminescence quantum yield and stability of CdSe-TOP, CdSe-ODA-TOPO, CdSe/CdS and CdSe/EP nanocomposites

    Science.gov (United States)

    Wei, Shutian; Zhu, Zhilin; Wang, Zhixiao; Wei, Gugangfen; Wang, Pingjian; Li, Hai; Hua, Zhen; Lin, Zhonghai

    2016-07-01

    Size-controllable monodisperse CdSe nanocrystals with different organic capping were prepared based on the hot-injection method. The effective separation of nucleation and growth was achieved by rapidly mixing two highly reactive precursors. As a contrast, we prepared CdSe/CdS nanocrystals (NCs) successfully based on the selective ion layer adsorption and reaction (SILAR) technique. This inorganic capping obtained higher photoluminescence quantum yield (PLQY) of 59.3% compared with organic capping of 40.8%. Furthermore, the CdSe-epoxy resin (EP) composites were prepared by adopting a flexible ex situ method, and showed excellent stability in the ambient environment for one year. So the composites with both high PLQY of nanocrystals and excellent stability are very promising to device application.

  20. Perturbation of planarity as the possible mechanism of solvent-dependent variations of fluorescence quantum yield in 2-aryl-3-hydroxychromones

    Science.gov (United States)

    Klymchenko, Andrey S.; Pivovarenko, Vasyl G.; Demchenko, Alexander P.

    2003-03-01

    In order to understand the unexpectedly low quantum yields of 3-hydroxyflavones (3-HFs) in certain solvents, such as acetonitrile or ethyl acetate, the comparative study of solvent-dependent properties of parent 3-HF, 2-furyl-3-hydroxychromone and 2-benzofuryl-3-hydroxychromone derivatives have been performed. The results suggest that the formation of intermolecular hydrogen bond of 3-hydroxy group with the solvent favors non-planar conformations of phenyl group with respect to chromone system. This steric hindrance is not observed in the case of furan- and benzofuran-substituted 3-hydroxychromones (3-HCs). These results suggesting a new strategy for dramatic improvement of fluorescence properties of 3-HCs as two-wavelength ratiometric fluorescence probes.

  1. Photochemistry of UV-excited trifluoroacetylacetone and hexafluoroacetylacetone II: Quantum yield and rate constants of hydrogen fluoride photoelimination forming fluorinated methylfuranones

    Science.gov (United States)

    Disselkoen, Kyle R.; Alsum, Joel R.; Thielke, Timothy A.; Muyskens, Mark A.

    2017-03-01

    The photochemistry of gas-phase 1,1,1-trifluoroacetylacetone (TFAA) and 1,1,1,5,5,5-hexafluoroacetylacetone (HFAA) excited with ultraviolet light involves a significant photoelimination channel producing HF and difluoromethylfuranone or pentafluoromethylfuranone, respectively. We report collisional self-quenching of the experimentally-determined relative quantum yield, and determine rate constants of 0.27 ± 0.03 and 0.33 ± 0.04 μs-1, for HFAA and TFAA respectively. A strong collision model is consistent with the observed quenching. The data suggest that this elimination is the primary photochemical fate at low pressure in both cases. The TFAA rate constant is larger than that for HFAA, in spite of TFAA having half as many fluorine atoms as HFAA.

  2. Determination of Quantum Yield for the Photochemical Decomposition of Dichloramine-B and Dibromamine-B in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    K. N. Mohana

    2007-01-01

    Full Text Available The photolysis of dihaloamines (RNX2, viz., dichloramine-B (DCB and dibromamine-B (DBB in aqueous acetic acid (1:1 v/v solutions has been studied with the UV light source (λ= 2537 Å. The experimental rate law obtained is - d [RNX2] / dt = k' Io / [RNX2], where Io is the intensity of incident light. The addition of benzenesulphonamide, the product of photolysis or uranyl ion had no significant effect on the rate of photochemical decomposition. A slight decrease in the rate has been observed by the addition of NaCl / NaBr to DCB / DBB solutions. The quantum yield (Φ for the photolytic decomposition has been computed. A suitable photolytic mechanism and a rate law consistent with the observed results have been proposed.

  3. Slow-Injection Growth of Seeded CdSe/CdS Nanorods with Unity Fluorescence Quantum Yield and Complete Shell to Core Energy Transfer.

    Science.gov (United States)

    Coropceanu, Igor; Rossinelli, Aurelio; Caram, Justin R; Freyria, Francesca S; Bawendi, Moungi G

    2016-03-22

    A two-step process has been developed for growing the shell of CdSe/CdS core/shell nanorods. The method combines an established fast-injection-based step to create the initial elongated shell with a second slow-injection growth that allows for a systematic variation of the shell thickness while maintaining a high degree of monodispersity at the batch level and enhancing the uniformity at the single-nanorod level. The second growth step resulted in nanorods exhibiting a fluorescence quantum yield up to 100% as well as effectively complete energy transfer from the shell to the core. This improvement suggests that the second step is associated with a strong suppression of the nonradiative channels operating both before and after the thermalization of the exciton. This hypothesis is supported by the suppression of a defect band, ubiquitous to CdSe-based nanocrystals after the second growth.

  4. Absorption and Quantum Yield of Single Conjugated Polymer Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) Molecules

    Science.gov (United States)

    2017-01-01

    We simultaneously measured the absorption and emission of single conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) molecules in a poly(methyl methacrylate) (PMMA) matrix using near-critical xenon to enhance the photothermal contrast for direct absorption measurements. We directly measured the number of monomers and the quantum yield of single conjugated polymer molecules. Simultaneous absorption and emission measurements provided new insight into the photophysics of single conjugated polymers under optical excitation: quenching in larger molecules is more efficient than in smaller ones. Photoinduced traps and defects formed under prolonged illumination lead to decrease of both polymer fluorescence and absorption signals with the latter declining slower. PMID:28221806

  5. Quantum Photonics Beyond Conventional Computing

    Science.gov (United States)

    2015-07-10

    Optica , 2, 510-516, (2015) • J. Carolan et al.,‘Universal linear optics’, Science, 349, 711-716, (2015) • N. Russell et al., ‘Direct dialling of Haar...Zhou, H. Cable, R. Whittaker, P. Shadbolt, J. L. O’Brien, and J. C. F. Matthews, Optica 2, 510 (2015). [13] M. Reck, A. Zeilinger, H. J. Bernstein, and P

  6. Luminescent pincer platinum(II) complexes with emission quantum yields up to almost unity: photophysics, photoreductive C-C bond formation, and materials applications.

    Science.gov (United States)

    Chow, Pui-Keong; Cheng, Gang; Tong, Glenna So Ming; To, Wai-Pong; Kwong, Wai-Lun; Low, Kam-Hung; Kwok, Chi-Chung; Ma, Chensheng; Che, Chi-Ming

    2015-02-09

    Luminescent pincer-type Pt(II)  complexes supported by C-deprotonated π-extended tridentate RC^N^NR' ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time-resolved fluorescence measurements and time-dependent DFT calculations together reveal the dependence of excited-state structural distortions of [Pt(RC^N^NR')(CC-C6 F5 )] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R-C^N^NR')(CC-Ar)] are efficient photocatalysts for visible-light-induced reductive CC bond formation. The [Pt(R-C^N^NR')(CC-C6 F5 )] complexes perform strongly as phosphorescent dopants for green- and red-emitting organic light-emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two-photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs).

  7. Arbuscular mycorrhizal symbiosis ameliorates the optimum quantum yield of photosystem II and reduces non-photochemical quenching in rice plants subjected to salt stress.

    Science.gov (United States)

    Porcel, Rosa; Redondo-Gómez, Susana; Mateos-Naranjo, Enrique; Aroca, Ricardo; Garcia, Rosalva; Ruiz-Lozano, Juan Manuel

    2015-08-01

    Rice is the most important food crop in the world and is a primary source of food for more than half of the world population. However, salinity is considered the most common abiotic stress reducing its productivity. Soil salinity inhibits photosynthetic processes, which can induce an over-reduction of the reaction centres in photosystem II (PSII), damaging the photosynthetic machinery. The arbuscular mycorrhizal (AM) symbiosis may improve host plant tolerance to salinity, but it is not clear how the AM symbiosis affects the plant photosynthetic capacity, particularly the efficiency of PSII. This study aimed at determining the influence of the AM symbiosis on the performance of PSII in rice plants subjected to salinity. Photosynthetic activity, plant gas-exchange parameters, accumulation of photosynthetic pigments and rubisco activity and gene expression were also measured in order to analyse comprehensively the response of the photosynthetic processes to AM symbiosis and salinity. Results showed that the AM symbiosis enhanced the actual quantum yield of PSII photochemistry and reduced the quantum yield of non-photochemical quenching in rice plants subjected to salinity. AM rice plants maintained higher net photosynthetic rate, stomatal conductance and transpiration rate than nonAM plants. Thus, we propose that AM rice plants had a higher photochemical efficiency for CO2 fixation and solar energy utilization and this increases plant salt tolerance by preventing the injury to the photosystems reaction centres and by allowing a better utilization of light energy in photochemical processes. All these processes translated into higher photosynthetic and rubisco activities in AM rice plants and improved plant biomass production under salinity.

  8. Yield and quality criteria in organically and conventionally grown tomatoes in Turkey Produção e qualidade de tomates cultivados sob sistemas orgânico e convencional na Turquia

    Directory of Open Access Journals (Sweden)

    Ersin Polat

    2010-08-01

    Full Text Available The term 'organically grown food' denotes products that have been produced in accordance with the principles and practices of organic agriculture. The use of alternatives to synthetic fertilizers is an important issue in organic systems. A two-year field experiment to evaluate effects of organic fertilizers on the yield and quality of open field grown tomatoes (Lycopersicon esculentum Mill. was carried out in Southern Turkey in 2000 and 2001. Combinations of manure, blood flour and micronutrient preparations were used for fertilization, and conventional mineral fertilization was included as the control. Yield did not differ between the fertilization and the Conventional treatments in the first year of the study, but the highest yield was obtained from conventional in the second year. No differences were found between treatments in terms of fruit soluble sugar content or citric acid. The application of organic fertilizers positively affected the micronutritional element content of tomato fruits compared to the conventional treatment. Organic fertilization results in improved yield and fruit quality compared to conventional fertilization. In addition, organic fertilization should be supported in order to facilitate reuse and disposal of organic wastes and to maintain and/or increase soil fertility.O termo "alimentos cultivados organicamente" denota produtos que tenham sido produzidos em conformidade com os princípios e práticas da agricultura orgânica. O uso de alternativas para fertilizantes sintéticos é uma questão importante em sistemas orgânicos. Um experimento de campo foi conduzido no sul da Turquia em 2000 e 2001 para avaliar os efeitos da adubação orgânica na produtividade e na qualidade de tomates (Lycopersicon esculentum Mill, cultivados em campo aberto. Combinações de esterco, farinha de sangue e preparações de micronutrientes foram utilizados para a fertilização, e adubações minerais convencionais foram inclu

  9. Quantum Nanomechanics

    OpenAIRE

    2008-01-01

    Quantum Nanomechanics is the emerging field which pertains to the mechanical behavior of nanoscale systems in the quantum domain. Unlike the conventional studies of vibration of molecules and phonons in solids, quantum nanomechanics is defined as the quantum behavior of the entire mechanical structure, including all of its constituents--the atoms, the molecules, the ions, the electrons as well as other excitations. The relevant degrees of freedom of the system are described by macroscopic var...

  10. Origin of the Photoluminescence Quantum Yields Enhanced by Alkane-Termination of Freestanding Silicon Nanocrystals: Temperature-Dependence of Optical Properties

    Science.gov (United States)

    Ghosh, Batu; Takeguchi, Masaki; Nakamura, Jin; Nemoto, Yoshihiro; Hamaoka, Takumi; Chandra, Sourov; Shirahata, Naoto

    2016-11-01

    On the basis of the systematic study on temperature dependence of photoluminescence (PL) properties along with relaxation dynamics we revise a long-accepted mechanism for enhancing absolute PL quantum yields (QYs) of freestanding silicon nanocrystals (ncSi). A hydrogen-terminated ncSi (ncSi:H) of 2.1 nm was prepared by thermal disproportination of (HSiO1.5)n, followed by hydrofluoric etching. Room-temperature PL QY of the ncSi:H increased twentyfold only by hydrosilylation of 1-octadecene (ncSi-OD). A combination of PL spectroscopic measurement from cryogenic to room temperature with structural characterization allows us to link the enhanced PL QYs with the notable difference in surface structure between the ncSi:H and the ncSi-OD. The hydride-terminated surface suffers from the presence of a large amount of nonradiative relaxation channels whereas the passivation with alkyl monolayers suppresses the creation of the nonradiative relaxation channels to yield the high PL QY.

  11. High quantum-yield CdSexS1-x/ZnS core/shell quantum dots for warm white light-emitting diodes with good color rendering.

    Science.gov (United States)

    Duan, Hongyan; Jiang, Yang; Zhang, Yugang; Sun, Dapeng; Liu, Chao; Huang, Jian; Lan, Xinzheng; Zhou, Hongyang; Chen, Lei; Zhong, Honghai

    2013-07-19

    Composition-controllable ternary CdSe(x)S(1-x) quantum dots (QDs) with multiple emission colors were obtained via a hot-injection-like method at a relatively low injection temperature (230 ° C) in octadecene. Then highly fluorescent CdSe(x)S(1-x)/ZnS core/shell (CS) QDs were synthesized by a facile single-molecular precursor approach. The fluorescent quantum yield of the resulting green (λ(em) = 523 nm), yellow (λ(em) = 565 nm) and red (λ(em) = 621 nm) emission of CS QDs in toluene reached up to 85%, 55% and 39%, respectively. Moreover, a QDs white light-emitting diode (QDs-WLED) was fabricated by hybridizing green-, yellow- and red-emitting CdSe(x)S(1-x)/ZnS CS QDs/epoxy composites on a blue InGaN chip. The resulting four-band RYGB QDs-WLED showed good performance with CIE-1931 coordinates of (0.4137, 0.3955), an R(a) of 81, and a T(c) of 3360 K at 30 mA, which indicated the combination of multiple-color QDs with high fluorescence QYs in LEDs as a promising approach to obtain warm WLEDs with good color rendering.

  12. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    2008-07-01

    Full Text Available The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime, is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler’s “spacetime foam” intuition. (iii Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv A derivation of the Bekenstein–Hawking black-hole entropy. (v Low-energy calculations, yielding n-point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  13. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. "Batavia" (green) and cv. "Lollo Rossa" (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m(-2) s(-1) for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m(-2) s(-1) from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m(-2) s(-1) from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m(-2) s(-1) from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m(-2) s(-1) from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  14. Dynamics of cover, UV-protective pigments, and quantum yield in biological soil crust communities of an undisturbed Mojave Desert shrubland

    Science.gov (United States)

    Belnap, J.; Phillips, S.L.; Smith, S.D.

    2007-01-01

    Biological soil crusts are an integral part of dryland ecosystems. We monitored the cover of lichens and mosses, cyanobacterial biomass, concentrations of UV-protective pigments in both free-living and lichenized cyanobacteria, and quantum yield in the soil lichen species Collema in an undisturbed Mojave Desert shrubland. During our sampling time, the site received historically high and low levels of precipitation, whereas temperatures were close to normal. Lichen cover, dominated by Collema tenax and C. coccophorum, and moss cover, dominated by Syntrichia caninervis, responded to both increases and decreases in precipitation. This finding for Collema spp. at a hot Mojave Desert site is in contrast to a similar study conducted at a cool desert site on the Colorado Plateau in SE Utah, USA, where Collema spp. cover dropped in response to elevated temperatures, but did not respond to changes in rainfall. The concentrations of UV-protective pigments in free-living cyanobacteria at the Mojave Desert site were also strongly and positively related to rainfall received between sampling times (R2 values ranged from 0.78 to 0.99). However, pigment levels in the lichenized cyanobacteria showed little correlation with rainfall. Quantum yield in Collema spp. was closely correlated with rainfall. Climate models in this region predict a 3.5-4.0 ??C rise in temperature and a 15-20% decline in winter precipitation by 2099. Based on our data, this rise in temperature is unlikely to have a strong effect on the dominant species of the soil crusts. However, the predicted drop in precipitation will likely lead to a decrease in soil lichen and moss cover, and high stress or mortality in soil cyanobacteria as levels of UV-protective pigments decline. In addition, surface-disturbing activities (e.g., recreation, military activities, fire) are rapidly increasing in the Mojave Desert, and these disturbances quickly remove soil lichens and mosses. These stresses combined are likely to lead to

  15. A Facile and Low-Cost Method to Enhance the Internal Quantum Yield and External Light-Extraction Efficiency for Flexible Light-Emitting Carbon-Dot Films

    Science.gov (United States)

    Jiang, Z. C.; Lin, T. N.; Lin, H. T.; Talite, M. J.; Tzeng, T. T.; Hsu, C. L.; Chiu, K. P.; Lin, C. A. J.; Shen, J. L.; Yuan, C. T.

    2016-01-01

    Solution-processed, non-toxic carbon dots (CDs) have attracted much attention due to their unique photoluminescence (PL) properties. They are promising emissive layers for flexible light-emitting devices. To this end, the CDs in pristine aqueous solutions need to be transferred to form solid-state thin films without sacrificing their original PL characteristics. Unfortunately, solid-state PL quenching induced by extra non-radiative (NR) energy transfer among CDs would significantly hinder their practical applications in optoelectronics. Here, a facile, low-cost and effective method has been utilized to fabricate high-performance CD/polymer light-emitting flexible films with submicron-structured patterns. The patterned polymers can serve as a solid matrix to disperse and passivate CDs, thus achieving high internal quantum yields of 61%. In addition, they can act as an out-coupler to mitigate the waveguide-mode losses, approximately doubling the external light-extraction efficiency. Such CD/polymer composites also exhibit good photo-stability, and thus can be used as eco-friendly, low-cost phosphors for solid-state lighting.

  16. Host-Guest Chemistry between Perylene Diimide (PDI) Derivatives and 18-Crown-6: Enhancement in Luminescence Quantum Yield and Electrical Conductivity.

    Science.gov (United States)

    Lasitha, P; Prasad, Edamana

    2016-07-18

    Perylene diimide (PDI) derivatives exhibit a high propensity for aggregation, which causes the aggregation-induced quenching of emission from the system. Host-guest chemistry is one of the best-known methods for preventing aggregation through the encapsulation of guest molecules. Herein we report the use of 18-crown-6 (18-C-6) as a host system to disaggregate suitably substituted PDI derivatives in methanol. 18-C-6 formed complexes with amino-substituted PDIs in methanol, which led to disaggregation and enhanced emission from the systems. Furthermore, the embedding of the PDI⋅18-C-6 complexes in poly(vinyl alcohol) (PVA) films generated remarkably high emission quantum yields (60-70 %) from the PDI derivatives. More importantly, the host-guest systems were tested for their ability to conduct electricity in PVA films. The electrical conductivities of the self-assembled systems in PVA were measured by electrochemical impedance spectroscopy (EIS) and the highest conductivity observed was 2.42×10(-5)  S cm(-1) .

  17. Synthesis and characterization of (3-Aminopropyl)trimethoxy-silane (APTMS) functionalized Gd2O3:Eu3+ red phosphor with enhanced quantum yield

    Science.gov (United States)

    Jain, Akhil; Hirata, G. A.; Farías, M. H.; Castillón, F. F.

    2016-02-01

    We report the surface modification of nanocrystalline Gd2O3:Eu3+ phosphor by (3-Aminopropyl)trimethoxysilane (APTMS). The nanoparticles were first coated with silica using the Stöber process, and then annealed at 650 °C for 2 h. Afterwards, APTMS was functionalized onto the silica layer to obtain Gd2O3:Eu3+ nanoparticles bearing amine groups on the surface. The effect of silica coating, and the subsequent annealing process on the crystallization of the nanophosphor were analyzed by x-ray diffraction (XRD). High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of a silica layer of ∼45 nm thickness. X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of silica and the amine groups. Photoluminescence (PL) analysis demonstrated an increased emission after functionalization of nanoparticles. Absolute quantum yield (QY) measurements revealed an 18% enhancement in QY in functionalized nanoparticles compared with unmodified nanoparticles, which is of great importance for their biomedical applications.

  18. Synthesis and characterization of (3-Aminopropyl)trimethoxy-silane (APTMS) functionalized Gd2O3:Eu(3+) red phosphor with enhanced quantum yield.

    Science.gov (United States)

    Jain, Akhil; Hirata, G A; Farías, M H; Castillón, F F

    2016-02-12

    We report the surface modification of nanocrystalline Gd2O3:Eu(3+) phosphor by (3-Aminopropyl)trimethoxysilane (APTMS). The nanoparticles were first coated with silica using the Stöber process, and then annealed at 650 °C for 2 h. Afterwards, APTMS was functionalized onto the silica layer to obtain Gd2O3:Eu(3+) nanoparticles bearing amine groups on the surface. The effect of silica coating, and the subsequent annealing process on the crystallization of the nanophosphor were analyzed by x-ray diffraction (XRD). High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of a silica layer of ∼45 nm thickness. X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of silica and the amine groups. Photoluminescence (PL) analysis demonstrated an increased emission after functionalization of nanoparticles. Absolute quantum yield (QY) measurements revealed an 18% enhancement in QY in functionalized nanoparticles compared with unmodified nanoparticles, which is of great importance for their biomedical applications.

  19. A Brown Mesoporous TiO2-x /MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution.

    Science.gov (United States)

    Xing, Mingyang; Zhang, Jinlong; Qiu, Bocheng; Tian, Baozhu; Anpo, Masakazu; Che, Michel

    2015-04-24

    A brown mesoporous TiO2-x /MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record-breaking quantum yield (Φ = 46%) and a high photon-hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H2 production, which are all higher than that of the black hydrogen-doped TiO2 (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO2 /MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high-concentration F doping and the synergistic effect between lattice Ti(3+)-F and surface Ti(3+)-F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H2 for these catalysts. The as-prepared F-doped composite is an ideal solar light-driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H2 production.

  20. Cupriphication of gold to sensitize d10–d10 metal–metal bonds and near-unity phosphorescence quantum yields

    Science.gov (United States)

    Galassi, Rossana; Ghimire, Mukunda M.; Otten, Brooke M.; Ricci, Simone; McDougald, Roy N.; Almotawa, Ruaa M.; Alhmoud, Dieaa; Ivy, Joshua F.; Rawashdeh, Abdel-Monem M.; Nesterov, Vladimir N.; Reinheimer, Eric W.; Daniels, Lee M.; Burini, Alfredo; Omary, Mohammad A.

    2017-01-01

    Outer-shell s0/p0 orbital mixing with d10 orbitals and symmetry reduction upon cupriphication of cyclic trinuclear trigonal-planar gold(I) complexes are found to sensitize ground-state Cu(I)–Au(I) covalent bonds and near-unity phosphorescence quantum yields. Heterobimetallic Au4Cu2 {[Au4(μ-C2,N3-EtIm)4Cu2(µ-3,5-(CF3)2Pz)2], (4a)}, Au2Cu {[Au2(μ-C2,N3-BzIm)2Cu(µ-3,5-(CF3)2Pz)], (1) and [Au2(μ-C2,N3-MeIm)2Cu(µ-3,5-(CF3)2Pz)], (3a)}, AuCu2 {[Au(μ-C2,N3-MeIm)Cu2(µ-3,5-(CF3)2Pz)2], (3b) and [Au(μ-C2,N3-EtIm)Cu2(µ-3,5-(CF3)2Pz)2], (4b)} and stacked Au3/Cu3 {[Au(μ-C2,N3-BzIm)]3[Cu(µ-3,5-(CF3)2Pz)]3, (2)} form upon reacting Au3 {[Au(μ-C2,N3-(N-R)Im)]3 ((N-R)Im = imidazolate; R = benzyl/methyl/ethyl = BzIm/MeIm/EtIm)} with Cu3 {[Cu(μ-3,5-(CF3)2Pz)]3 (3,5-(CF3)2Pz = 3,5-bis(trifluoromethyl)pyrazolate)}. The crystal structures of 1 and 3a reveal stair-step infinite chains whereby adjacent dimer-of-trimer units are noncovalently packed via two Au(I)⋯Cu(I) metallophilic interactions, whereas 4a exhibits a hexanuclear cluster structure wherein two monomer-of-trimer units are linked by a genuine d10–d10 polar-covalent bond with ligand-unassisted Cu(I)–Au(I) distances of 2.8750(8) Å each—the shortest such an intermolecular distance ever reported between any two d10 centers so as to deem it a “metal–metal bond” vis-à-vis “metallophilic interaction.” Density-functional calculations estimate 35–43 kcal/mol binding energy, akin to typical M–M single-bond energies. Congruently, FTIR spectra of 4a show multiple far-IR bands within 65–200 cm−1, assignable to vCu-Au as validated by both the Harvey–Gray method of crystallographic-distance-to-force-constant correlation and dispersive density functional theory computations. Notably, the heterobimetallic complexes herein exhibit photophysical properties that are favorable to those for their homometallic congeners, due to threefold-to-twofold symmetry reduction, resulting in cuprophilic

  1. A chlorophyll fluorescence analysis of photosynthetic efficiency, quantum yield and photon energy dissipation in PSII antennae of Lactuca sativa L. leaves exposed to cinnamic acid.

    Science.gov (United States)

    Hussain, M Iftikhar; Reigosa, Manuel J

    2011-11-01

    This study investigated the effects of cinnamic acid (CA) on growth, biochemical and physiological responses of Lactuca sativa L. CA (0.1, 0.5, 1.0 and 1.5 mM) treatments decreased plant height, root length, leaf and root fresh weight, but it did not affect the leaf water status. CA treatment (1.5 mM) significantly reduced F(v), F(m), photochemical efficiency of PSII (F(v)/F(m)) and quantum yield of PSII (ΦPSII) photochemistry in L. sativa. The photochemical fluorescence quenching (qP) and non-photochemical quenching (NPQ) were reduced after treatment with 1.5 mM CA. Fraction of photon energy absorbed by PS II antennae trapped by "open" PS II reaction centers (P) was reduced by CA (1.5 mM) while, portion of absorbed photon energy thermally dissipated (D) and photon energy absorbed by PSII antennae and trapped by "closed" PSII reaction centers (E) was increased. Carbon isotope composition ratios (δ(13)C) was less negative (-27.10) in CA (1.5 mM) treated plants as compared to control (-27.61). Carbon isotope discrimination (Δ(13)C) and ratio of intercellular CO(2) concentration (ci/ca) from leaf to air were also less in CA treated plants. CA (1.5 mM) also decreased the leaf protein contents of L. sativa as compared to control.

  2. X-ray induced singlet oxygen generation by nanoparticle-photosensitizer conjugates for photodynamic therapy: determination of singlet oxygen quantum yield

    Science.gov (United States)

    Clement, Sandhya; Deng, Wei; Camilleri, Elizabeth; Wilson, Brian C.; Goldys, Ewa M.

    2016-01-01

    Singlet oxygen is a primary cytotoxic agent in photodynamic therapy. We show that CeF3 nanoparticles, pure as well as conjugated through electrostatic interaction with the photosensitizer verteporfin, are able to generate singlet oxygen as a result of UV light and 8 keV X-ray irradiation. The X-ray stimulated singlet oxygen quantum yield was determined to be 0.79 ± 0.05 for the conjugate with 31 verteporfin molecules per CeF3 nanoparticle, the highest conjugation level used. From this result we estimate the singlet oxygen dose generated from CeF3-verteporfin conjugates for a therapeutic dose of 60 Gy of ionizing radiation at energies of 6 MeV and 30 keV to be (1.2 ± 0.7) × 108 and (2.0 ± 0.1) × 109 singlet oxygen molecules per cell, respectively. These are comparable with cytotoxic doses of 5 × 107-2 × 109 singlet oxygen molecules per cell reported in the literature for photodynamic therapy using light activation. We confirmed that the CeF3-VP conjugates enhanced cell killing with 6 MeV radiation. This work confirms the feasibility of using X- or γ- ray activated nanoparticle-photosensitizer conjugates, either to supplement the radiation treatment of cancer, or as an independent treatment modality.

  3. Synthesis of Novel Hyperbranched Polybenzo-Bisthiazole Amide with Donor–Acceptor (D-A Architecture, High Fluorescent Quantum Yield and Large Stokes Shift

    Directory of Open Access Journals (Sweden)

    Xiaobing Hu

    2017-07-01

    Full Text Available Two novel highly fluorescent hyperbranched polybenzobisthiazole amides with a donor–acceptor architecture and large Stokes shift were rationally designed and synthesized. The chemical structures of the prepared hyperbranched polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR analysis, Hydrogen Nuclear Magnetic Resonance (1H-NMR analysis, and Gel Permeation Chromatography (GPC analysis. These two polymers were soluble in dimethyl sulfoxide (DMSO and N,N-dimethylformamide (DMF, and their DMSO and DMF solutions emitted strong green light (517–537 nm with high quantum yields (QYs and large Stokes shifts. Their relative fluorescence QYs in the DMSO solution were calculated as 77.75% and 81.14% with the Stokes shifts of 137 nm (0.86 eV and 149 nm (0.92 eV for HP–COOH and HP–NH2, respectively, using quinine sulfate as the standard. In the DMF solution, the QYs of HP–COOH and HP–NH2 were calculated as 104.65% and 118.72%, with the Stokes shifts of 128 nm (0.79 eV and 147 nm (0.87 eV, respectively. Their films mainly emitted strong blue light with the maximum emission wavelengths of 436 nm and 480 nm for HP–COOH and HP–NH2, respectively. The Stokes shifts for HP–COOH and HP–NH2 films were 131 nm (0.42 eV and 179 nm (0.86 eV, respectively. They are promising candidates for luminescent solar concentrators and blue light emitting materials.

  4. Nitrogen- and irradiance-dependent variations of the maximum quantum yield of carbon fixation in eutrophic, mesotrophic and oligotrophic marine systems

    Science.gov (United States)

    Babin, Marcel; Morel, André; Claustre, Hervé; Bricaud, Annick; Kolber, Zbigniew; Falkowski, Paul G.

    1996-08-01

    Natural variability of the maximum quantum yield of carbon fixation ( φC max), as determined from the initial slope of the photosynthesis-irradiance curve and from light absorption measurements, was studied at three sites in the northeast tropical Atlantic representing typical eutrophic, mesotrophic and oligotrophic regimes. At the eutrophic and mesotrophic sites, where the mixed layer extended deeper than the euphotic layer, all photosynthetic parameters were nearly constant with depth, and φC max averaged between 0.05 and 0.03 molC (mol quanta absorbed) -1, respectively. At the oligotrophic site, a deep chlorophyll maximum (DCM) existed and φC max varied from ca 0.005 in the upper nutrient-depleted mixed layer to 0.063 below the DCM in stratified waters. firstly, φC max was found roughly to covary with nitrate concentration between sites and with depth at the oligotrophic site, and secondly, it was found to decrease with increasing relative concentrations of non-photosynthetic pigments. The extent of φC max variations directly related to nitrate concentration was inferred from variations in the fraction of functional PS2 reaction centers ( f), measured using fast repetition rate fluorometry. Covariations between f and nitrate concentration indicate that the latter factor may be responsible for a 2-fold variation in φC max. Moreover, partitioning light absorption between photosynthetic and non-photosynthetic pigments suggests that the variable contribution of the non-photosynthetic absorption may explain a 3-fold variation in φC max, as indicated by variations in the effective absorption cross-section of photosystem 2 ( σPS2). Results confirm the role of nitrate in φC max variation, and emphasize those of light and vertical mixing.

  5. Effects of Controlled Release Urea Combined with Conventional Urea on Grain Yield and Nitrogen Use Efficiency of Winter Wheat%控释肥料配施对冬小麦产量和氮肥利用的影响

    Institute of Scientific and Technical Information of China (English)

    栗丽; 洪坚平; 王宏庭; 谢英荷

    2012-01-01

    The field experiment was conducted by using a randomized complete block design to investigate the effects of different dosages coated controlled release urea(CRU) combined with conventional urea (U) used as basal application on the growth and development, grain yield, nitrogen uptake and utilization of winter wheat in this study. Five treatments were set, i.e. control (CK), 100% U (T1), 100% CRU (T2), 80% CRU + 20% U (T3), 60% CRU + 40% U (T4). The results showed that the 1000-grain weight, grain number per ear, harvest index and grain yield were significantly increased in the treatments of T3 and T4 compared with T1 treatment in the same N -application. The grain yield of winter wheat was increased by 7. 42% -13. 12%. Besides, in comparison with the T1 treatment, the amount of nitrogen accumulation in wheat grain was increased and the amount of residual nitrogen in vegetative organs was reduced at the mature stage in treatments T3 and T4. The nitrogen use efficiency were increased by 8. 37% ~ 14. 05% and the soil nitrogen dependency ratio was reduced by 7. 43% -11. 04% in these two treatments. Composite application of controlled-release urea and traditional urea could reduce fertilizer costs to some extent and improve the economic efficiency. In this study, the T4 treatment was recommended as the appropriate combination of controlled - release urea and traditional urea for the high grain yield, nitrogen use efficiency and maximum economic benefits.%采用完全随机区组设计,通过田间试验研究不同量的控释尿素(CRU)与普通尿素(U)配合基施(100%U,T1;100% CRU,T2;80% CRU+20%U,T3;60% CRU+40%U,T4)对冬小麦生长发育、产量及氮素吸收利用的影响.结果表明,在施氮量相等条件下,控释尿素与普通尿素配施处理(T3和T4)冬小麦千粒重、穗粒数和收获指数与单施尿素(T1)相比显著增加,冬小麦产量提高7.42%~13.12%;此外,两种尿素配施能增加冬小麦成熟期籽粒中

  6. Photoactive yellow protein from the purple phototrophic bacterium, Ectothiorhodospira halophila. Quantum yield of photobleaching and effects of temperature, alcohols, glycerol, and sucrose on kinetics of photobleaching and recovery.

    Science.gov (United States)

    Meyer, T E; Tollin, G; Hazzard, J H; Cusanovich, M A

    1989-09-01

    A water-soluble yellow protein from E. halophila was previously shown to be photoactive (Meyer, T. E., E. Yakali, M. A. Cusanovich, and G. Tollin. 1987. Biochemistry. 26:418-423). Pulsed laser excitation in the protein visible absorption band (maximum at 445 nm) causes a rapid bleach of color (k = 7.5 x 10(3) s-1) followed by a slower dark recovery (k = 2.6 s-1). This is analogous to the photocycle of sensory rhodopsin II from Halobacterium (which also has k = 2.6 s-1 for recovery). We have now determined the quantum yield of the photobleaching process to be 0.64, which is comparable with that of bacteriorhodopsin (0.25), and is thus large enough to be biologically significant. Although the photoreactions of yellow protein were previously shown to be relatively insensitive to pH, ionic strength and the osmoregulator betaine, the present experiments demonstrate that temperature, glycerol, sucrose, and various alcohol-water mixtures strongly influence the kinetics of photobleaching and recovery. The effect of temperature follows normal Arrhenius behavior for the bleach reaction (Ea = 15.5 kcal/mol). The rate constant for the recovery reaction increases with temperature between 5 degrees C and 35 degrees C, but decreases above 35 degrees C indicating alternate conformations with differing kinetics. There is an order of magnitude decrease in the rate constant for photobleaching in both glycerol and sucrose solutions that can be correlated with the changes in viscosity. We conclude from this that the protein undergoes a conformational change as a consequence of the photoinduced bleach. Recovery kinetics are affected by glycerol and sucrose to a much smaller extent and in a more complicated manner. Aliphatic, monofunctional alcohol-water solutions increase the rate constant for the bleach reaction and decrease the rate constant for the recovery reaction, each by an order of magnitude. These effects do not correlate with dielectric constant, indicating that the photocycle

  7. Quantum Cat's Dilemma

    CERN Document Server

    Makowski, M; Makowski, Marcin; Piotrowski, Edward W.

    2005-01-01

    We study a quantum version of the sequential game illustrating problems connected with making rational decisions. We compare the results that the two models (quantum and classical) yield. In the quantum model intransitivity gains importance significantly. We argue that the quantum model describes our spontaneously shown preferences more precisely than the classical model, as these preferences are often intransitive.

  8. Sky-Blue Organic Light Emitting Diode with 37% External Quantum Efficiency Using Thermally Activated Delayed Fluorescence from Spiroacridine-Triazine Hybrid.

    Science.gov (United States)

    Lin, Ting-An; Chatterjee, Tanmay; Tsai, Wei-Lung; Lee, Wei-Kai; Wu, Meng-Jung; Jiao, Min; Pan, Kuan-Chung; Yi, Chih-Lung; Chung, Chin-Lung; Wong, Ken-Tsung; Wu, Chung-Chih

    2016-08-01

    Extremely efficient sky-blue organic electroluminescence with external quantum efficiency of ≈37% is achieved in a conventional planar device structure, using a highly efficient thermally activated delayed fluorescence emitter based on the spiroacridine-triazine hybrid and simultaneously possessing nearly unitary (100%) photoluminescence quantum yield, excellent thermal stability, and strongly horizontally oriented emitting dipoles (with a horizontal dipole ratio of 83%).

  9. Relative quantum yield of I-asterisk(2P1/2) in the tunable laser UV photodissociation of i-C3F7I and n-C3F7I - Effect of temperature and exciplex emission

    Science.gov (United States)

    Smedley, J. E.; Leone, S. R.

    1983-01-01

    Wavelength-specific relative quantum yields of metastable I from pulsed laser photodissociation of i-C3F7I and n-C3F7I in the range 265-336 nm are determined by measuring the time-resolved infrared emission from the atomic I(P-2(1/2) P-2(3/2) transition. It is shown that although this yield appears to be unity from 265 to 298 nm, it decreases dramatically at longer wavelengths. Values are also reported for the enhancement of emission from metastable I due to exciplex formation at several temperatures. The exciplex formation emission increases linearly with parent gas pressure, but decreases with increasing temperature. Absorption spectra of i- and n-C3F7I between 303 and 497 K are presented, and the effect of temperature on the quantum yields at selected wavelengths greater than 300 nm, where increasing the temperature enhances the absorption considerably, are given. The results are discussed in regard to the development of solar-pumped iodine lasers.

  10. Quantum Plasmonics

    OpenAIRE

    Diego Martin-Cano, Paloma A. Huidobro, Esteban Moreno; Diego Martin-Cano; Huidobro, Paloma A.; Esteban Moreno; Garcia-Vidal, F.J.

    2014-01-01

    Quantum plasmonics is a rapidly growing field of research that involves the study of the quantum properties of light and its interaction with matter at the nanoscale. Here, surface plasmons - electromagnetic excitations coupled to electron charge density waves on metal-dielectric interfaces or localized on metallic nanostructures - enable the confinement of light to scales far below that of conventional optics. In this article we review recent progress in the experimental and theoretical inve...

  11. On Quantum Algorithms

    CERN Document Server

    Cleve, R; Henderson, L; Macchiavello, C; Mosca, M

    1998-01-01

    Quantum computers use the quantum interference of different computational paths to enhance correct outcomes and suppress erroneous outcomes of computations. In effect, they follow the same logical paradigm as (multi-particle) interferometers. We show how most known quantum algorithms, including quantum algorithms for factorising and counting, may be cast in this manner. Quantum searching is described as inducing a desired relative phase between two eigenvectors to yield constructive interference on the sought elements and destructive interference on the remaining terms.

  12. Quantum data gathering

    Science.gov (United States)

    Blume-Kohout, Robin; Croke, Sarah; Zwolak, Michael

    2013-05-01

    Measurement of a quantum system - the process by which an observer gathers information about it - provides a link between the quantum and classical worlds. The nature of this process is the central issue for attempts to reconcile quantum and classical descriptions of physical processes. Here, we show that the conventional paradigm of quantum measurement is directly responsible for a well-known disparity between the resources required to extract information from quantum and classical systems. We introduce a simple form of quantum data gathering, ``coherent measurement'', that eliminates this disparity and restores a pleasing symmetry between classical and quantum statistical inference. To illustrate the power of quantum data gathering, we demonstrate that coherent measurements are optimal and strictly more powerful than conventional one-at-a-time measurements for the task of discriminating quantum states, including certain entangled many-body states (e.g., matrix product states).

  13. Comparison, artificial neural network modeling and genetic algorithm optimization of the resinoid and potassium yields from white lady’s bedstraw (Galium mollugo L. by conventional, reflux and ultrasound-assisted aqueous-ethanolic extraction

    Directory of Open Access Journals (Sweden)

    Milić Petar S.

    2013-01-01

    Full Text Available In this work, the yields of resinoid and potassium obtained from aerial parts of white lady’s bedstraw (Galium mollugo L. by maceration, reflux extraction and ultrasound-assisted extraction using aqueous ethanol solutions as solvents. The main goal was to define the influence of the extraction technique and the ethanol concentration on the resinoid and potassium yields. The resinoid and potassium yields were determined by the solvent evaporation from the liquid extracts to constant weight and the AAS emission method, respectively. The dependence of resinoid and potassium yields on the ethanol concentration was described by linear and quadratic polynomial models, respectively. The best potassium extraction selectivity of 0.077 g K/g of dry extract was achieved by maceration at the ethanol concentrations of 10 g/100 g. The artificial neural network (ANN was successfully applied to estimate the resinoid and potassium yields based on the ethanol concentration in the extracting solvent and the time duration for all three extraction techniques employed. The response surface methodology was also used to present the dependence of ANN results on the operating factors. The extraction process was optimized using the ANN model coupled with genetic algorithm. The maximum predicted resinoid and potassium yields of 30.4 and 1.67 g/100 g of dry plant were obtained by the ultrasonic extraction (80 min using the 10 g/100 g aqueous ethanol solution.

  14. Crop yield, root growth, and nutrient dynamics in a conventional and three organic cropping systems with different levels of external inputs and N re-cycling through fertility building crops

    DEFF Research Database (Denmark)

    Thorup-Kristensen, Kristian; Dresbøll, Dorte Bodin; Kristensen, Hanne Lakkenborg

    2012-01-01

    to reduce the reliance on import of external resources significantly. We compared a conventional system (C) and an organic system relying on manure import for soil fertility (O1) to two novel systems (O2 and O3) all based on the same crop rotation. The O2 and O3 systems represented new versions...... systems based on fertility building crops (green manures and catch crops). In short, the main distinctions were not observed between organic and conventional systems (i.e. C vs. O1, O2 and O3), but between systems based mainly on nutrient import vs. systems based mainly on fertility building crops (C......One of the core ideas behind organic production is that cropping systems should be less dependent on import of resources, and minimize negative effects on the surrounding environment compared to conventional production. However, even when clearly complying with regulations for organic production...

  15. Crop yield, root growth, and nutrient dynamics in a conventional and three organic cropping systems with different levels of external inputs and N re-cycling through fertility building crops

    DEFF Research Database (Denmark)

    Thorup-Kristensen, Kristian; Dresbøll, Dorte Bodin; Kristensen, Hanne Lakkenborg

    2012-01-01

    systems based on fertility building crops (green manures and catch crops). In short, the main distinctions were not observed between organic and conventional systems (i.e. C vs. O1, O2 and O3), but between systems based mainly on nutrient import vs. systems based mainly on fertility building crops (C...

  16. Photolithographic process for the patterning of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Na, Young Joo; Park, Sang Joon; Lee, Sang Wha [Department of Chemical and Bioengineering, Kyungwon University, Seongnam-si, Gyeonggi-Do 461-701 (Korea, Republic of); Kim, Jong Sung [Department of Chemical and Bioengineering, Kyungwon University, Seongnam-si, Gyeonggi-Do 461-701 (Korea, Republic of)], E-mail: jskim@kyungwon.ac.kr

    2008-09-15

    Recently, quantum dots have been used as molecular probes substituting for conventional organic fluorophores. Quantum dots are stable against photobleaching and have more controllable emission bands, broader absorption spectra, and higher quantum yields. In this study, an array of ZnS-coated CdSe quantum dots on a slide glass has been prepared by photolithographic method. The array pattern was prepared using a positive photoresist (AZ1518) and developer (AZ351). The patterned glass was silanized with 3-aminopropyltriethoxysilane (APTES), and carboxyl-coated quantum dots were selectively attached onto the array pattern. The silanization was examined by measuring contact angle and the surface of the array pattern was analyzed using AFM and fluorescent microscope.

  17. Single-particle tracking of quantum dot-conjugated prion proteins inside yeast cells

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Toshikazu; Kawai-Noma, Shigeko [Department of Biomolecular Engineering, Graduate School of Biosciences and Biotechnology, Tokyo Institute of Technology, B56, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501 (Japan); Pack, Chan-Gi [Cellular Informatics Laboratory, RIKEN Advanced Science Institute, Wako-shi, Saitama 351-0198 (Japan); Terajima, Hideki [Department of Biomolecular Engineering, Graduate School of Biosciences and Biotechnology, Tokyo Institute of Technology, B56, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501 (Japan); Yajima, Junichiro; Nishizaka, Takayuki [Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588 (Japan); Kinjo, Masataka [Laboratory of Molecular Cell Dynamics, Graduate School of Life Sciences, Hokkaido University, Sapporo 001-0021 (Japan); Taguchi, Hideki, E-mail: taguchi@bio.titech.ac.jp [Department of Biomolecular Engineering, Graduate School of Biosciences and Biotechnology, Tokyo Institute of Technology, B56, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501 (Japan)

    2011-02-25

    Research highlights: {yields} We develop a method to track a quantum dot-conjugated protein in yeast cells. {yields} We incorporate the conjugated quantum dot proteins into yeast spheroplasts. {yields} We track the motions by conventional or 3D tracking microscopy. -- Abstract: Yeast is a model eukaryote with a variety of biological resources. Here we developed a method to track a quantum dot (QD)-conjugated protein in the budding yeast Saccharomyces cerevisiae. We chemically conjugated QDs with the yeast prion Sup35, incorporated them into yeast spheroplasts, and tracked the motions by conventional two-dimensional or three-dimensional tracking microscopy. The method paves the way toward the individual tracking of proteins of interest inside living yeast cells.

  18. Devices used by automated milking systems are similarly accurate in estimating milk yield and in collecting a representative milk sample compared with devices used by farms with conventional milk recording

    NARCIS (Netherlands)

    Kamphuis, Claudia; Dela Rue, B.; Turner, S.A.; Petch, S.

    2015-01-01

    Information on accuracy of milk-sampling devices used on farms with automated milking systems (AMS) is essential for development of milk recording protocols. The hypotheses of this study were (1) devices used by AMS units are similarly accurate in estimating milk yield and in collecting

  19. High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

    2013-01-01

    In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

  20. High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

    2013-01-01

    In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

  1. Application of controlled-released urea combined with conventional urea on physiological indices, yield and quality of Chrysanthemum morifolium Ramat.%控释尿素与普通尿素配施对菊花生理指标及产量和质量的影响

    Institute of Scientific and Technical Information of China (English)

    祝丽香; 王建华; 高先涛

    2012-01-01

    2009和2010年采取田间实验方法研究控释尿素和普通尿素不同施用方式对菊花生长发育及产量和品质的影响。结果表明,孕蕾期菊花叶片可溶性蛋白质和叶绿素含量、硝酸还原酶活性、根系活力明显高于生长旺盛期和开花期,且施用尿素高于对照。控释尿素、控释尿素与普通尿素混合一次性基施可促进菊花生长发育前期干物质积累,分次施用有利于后期干物质积累。施用尿素增加单株花序数、百朵花序鲜重,对花序直径影响较少。两种尿素分别分次施用菊花产量明显高于一次性基施,控释尿素与普通尿素等量混合分次施用产量高于其它处理。与普通尿素单施相比,控释尿素提高了菊花总黄酮、蛋白质和可溶性糖含量,其中以控释尿素与普通尿素等量混合分次施用的最高。综合菊花产量和品质指标,在本实验条件下,控释尿素与普通尿素等量混合分次施用的效果最佳。%Nitrogen is one of the most important nutrients and plays a vital role in crop growth and yield production, rational nitrogen fertilization is essential to achieve an optimal yield and the desired product quality. Field experiments were conducted from 2009 to 2010 to compare the effects of controlled-release urea and conventional urea on the growth, yield and quality of Chrysanthemum morifolium. The results show that the physiological indices, including soluble protein content, chlorophyll content, nitrate reductase and root activities, are highest at the pregnant stage, and the indices in the treatments applied two kind of urea are higher than those of the control. The controlled-release urea and conventional urea applied as single basal application can improve growth and dry matter accumulation at the early stages of C. morifolium, while split fertilizations are more favorable to these in the later stages. The amounts of inflorescence number per plant and 100-inforescence flesh

  2. Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity

    Science.gov (United States)

    Pradeepa, S. M.; Bhojya Naik, H. S.; Vinay Kumar, B.; Indira Priyadarsini, K.; Barik, Atanu; Ravikumar Naik, T. R.

    2013-01-01

    In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6 × 104 M-1, 5.7 × 104 M-1 and 4.5 × 104 M-1, respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

  3. Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity.

    Science.gov (United States)

    Pradeepa, S M; Bhojya Naik, H S; Vinay Kumar, B; Indira Priyadarsini, K; Barik, Atanu; Ravikumar Naik, T R

    2013-01-15

    In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6×10(4) M(-1), 5.7×10(4) M(-1) and 4.5×10(4) M(-1), respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

  4. A father protocol for quantum broadcast channels

    CERN Document Server

    Dupuis, F; Dupuis, Fr\\'ed\\'eric; Hayden, Patrick

    2006-01-01

    We present a new protocol for quantum broadcast channels based on the fully quantum Slepian-Wolf protocol. The protocol yields an achievable rate region for entanglement-assisted transmission of quantum information through a quantum broadcast channel that can be considered the quantum analogue of Marton's region for classical broadcast channels. The protocol can be adapted to yield achievable rate regions for unassisted quantum communication and for entanglement-assisted classical communication. Regularized versions of all three rate regions are provably optimal.

  5. Quantum-chemical calculations of the metallofullerene yields in the X@C{sub 74}, L@C{sub 74}, and Z@C{sub 82} series

    Energy Technology Data Exchange (ETDEWEB)

    Uhlík, Filip [Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2 (Czech Republic); Slanina, Zdeněk; Nagase, Shigeru [Department of Theoretical Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Aichi (Japan)

    2015-01-22

    The contribution reports computations for Al@C{sub 82}, Sc@C{sub 82}, Y@C{sub 82} and La@C{sub 82} based on encapsulation into the IPR (isolated pentagon rule) C{sub 2ν} C{sub 82} cage and also on Mg@C{sub 74}, Ca@C{sub 74}, Sr@C{sub 74} and Ba@C{sub 74} based on encapsulation into the only C{sub 74} IPR cage as well as for three selected lanthanoids La@C{sub 74}, Yb@C{sub 74}, and Lu@C{sub 74}. Their structural and energetic characteristics are used for evaluations of the relative production yields, using the encapsulation Gibbs-energy and saturated metal pressures. It is shown that the results can be well related to the ionization potentials of the free metal atoms.

  6. Short-Term Responses in Maximum Quantum Yield of PSII (Fv/Fm to ex situ Temperature Treatment of Populations of Bryophytes Originating from Different Sites in Hokkaido, Northern Japan

    Directory of Open Access Journals (Sweden)

    Annika K. Jägerbrand

    2016-04-01

    Full Text Available There is limited knowledge available on the thermal acclimation processes for bryophytes, especially when considering variation between populations or sites. This study investigated whether short-term ex situ thermal acclimation of different populations showed patterns of site dependency and whether the maximum quantum yield of PSII (Fv/Fm could be used as an indicator of adaptation or temperature stress in two bryophyte species: Pleurozium schreberi (Willd. ex Brid. Mitt. and Racomitrium lanuginosum (Hedw. Brid. We sought to test the hypothesis that differences in the ability to acclimate to short-term temperature treatment would be revealed as differences in photosystem II maximum yield (Fv/Fm. Thermal treatments were applied to samples from 12 and 11 populations during 12 or 13 days in growth chambers and comprised: (1 10/5 °C; (2 20/10 °C; (3 25/15 °C; (4 30/20 °C (12 hours day/night temperature. In Pleurozium schreberi, there were no significant site-dependent differences before or after the experiment, while site dependencies were clearly shown in Racomitrium lanuginosum throughout the study. Fv/Fm in Pleurozium schreberi decreased at the highest and lowest temperature treatments, which can be interpreted as a stress response, but no similar trends were shown by Racomitrium lanuginosum.

  7. Quantum Memory as Light Pulses Quantum States Transformer

    Directory of Open Access Journals (Sweden)

    Vetlugin A.N.

    2015-01-01

    Full Text Available Quantum memory can operate not only as a write-in/readout device [1] for quantum light pulses and non-classical states generation [2] device but also as a quantum states of light transformer. Here the addressable parallel quantum memory [3] possibilities for this type of transformation are researched. Quantum memory operates as a conventional N-port interferometer with N equals to the number of the involved spin waves. As example we consider the ability to transform quantum states of two light pulses – in this case the quantum memory works as a mirror with a controlled transmission factor.

  8. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  9. Chemical processing of three-dimensional graphene networks on transparent conducting electrodes for depleted-heterojunction quantum dot solar cells.

    Science.gov (United States)

    Tavakoli, Mohammad Mahdi; Simchi, Abdolreza; Fan, Zhiyong; Aashuri, Hossein

    2016-01-07

    We present a novel chemical procedure to prepare three-dimensional graphene networks (3DGNs) as a transparent conductive film to enhance the photovoltaic performance of PbS quantum-dot (QD) solar cells. It is shown that 3DGN electrodes enhance electron extraction, yielding a 30% improvement in performance compared with the conventional device.

  10. An Acoustic Charge Transport Imager for High Definition Television Applications: Reliability Modeling and Parametric Yield Prediction of GaAs Multiple Quantum Well Avalanche Photodiodes. Degree awarded Oct. 1997

    Science.gov (United States)

    Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Yun, Ilgu

    1994-01-01

    Reliability modeling and parametric yield prediction of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiodes (APDs), which are of interest as an ultra-low noise image capture mechanism for high definition systems, have been investigated. First, the effect of various doping methods on the reliability of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiode (APD) structures fabricated by molecular beam epitaxy is investigated. Reliability is examined by accelerated life tests by monitoring dark current and breakdown voltage. Median device lifetime and the activation energy of the degradation mechanism are computed for undoped, doped-barrier, and doped-well APD structures. Lifetimes for each device structure are examined via a statistically designed experiment. Analysis of variance shows that dark-current is affected primarily by device diameter, temperature and stressing time, and breakdown voltage depends on the diameter, stressing time and APD type. It is concluded that the undoped APD has the highest reliability, followed by the doped well and doped barrier devices, respectively. To determine the source of the degradation mechanism for each device structure, failure analysis using the electron-beam induced current method is performed. This analysis reveals some degree of device degradation caused by ionic impurities in the passivation layer, and energy-dispersive spectrometry subsequently verified the presence of ionic sodium as the primary contaminant. However, since all device structures are similarly passivated, sodium contamination alone does not account for the observed variation between the differently doped APDs. This effect is explained by the dopant migration during stressing, which is verified by free carrier concentration measurements using the capacitance-voltage technique.

  11. Study on fluorescence absolute quantum yield and lifetime of europium complexes by doping yttrium%掺杂钇的铕稀土配合物的荧光绝对量子产率和寿命的研究

    Institute of Scientific and Technical Information of China (English)

    费邦忠; 陶栋梁; 张宏; 崔玉民; 张坤; 王永忠; 杨森林; 鲁仕梅

    2016-01-01

    A series of Co-luminescence EuxY1-x(TTA)3phen were synthesized in anhydrous ethanol by using Eu3+and Y3+as central ions and 2-Thenoyltrifluoroacetone (TTA) and 1,10-phenanthroline (phen) as ligands. IR spectra of the ligand TTA and EuxY1-x(TTA)3phen were determined. The absolute fluorescence quantum yields and average fluorescence lifetimes of europium complexes undergo great change after the europium complexes are doped Y into. With the Y content increasing, the absolute quantum yields of EuxY1- x(TTA)3phen first increase and then decrease, and the average fluorescence lifetimes of EuxY1- x (TTA)3phen become shorter in a wave-like pattern. These results indicate that Y-doped results in intramolecular microstructure change of EuxY1-x(TTA)3phen, which results in change of intramolecular energy transfer system of EuxY1-x(TTA)3phen.%在无水乙醇中,利用Eu3+和Y3+作为中心离子,α-噻吩甲酰三氟丙酮(TTA)和1,10-邻菲啰啉(phen)作为配体制备了一系列共发光稀土配合物EuxY1-x(TTA)3phen,并对TTA和EuxY1-x(TTA)3phen进行了红外表征。掺杂钇的铕配合物与没掺杂钇相比,荧光绝对量子产率和平均寿命都发生了很大变化,随着钇含量的增大,EuxY1-x(TTA)3phen的荧光绝对量子产率先增大,然后减小,而平均寿命则以波动方式逐渐减小,说明钇的掺杂改变了EuxY1-x(TTA)3phen的分子微观结构,从而改变了EuxY1-x(TTA)3phen的能量传递方式。

  12. Yield Improvement in Steel Casting (Yield II)

    Energy Technology Data Exchange (ETDEWEB)

    Richard A. Hardin; Christoph Beckermann; Tim Hays

    2002-02-18

    This report presents work conducted on the following main projects tasks undertaken in the Yield Improvement in Steel Casting research program: Improvement of Conventional Feeding and Risering Methods, Use of Unconventional Yield Improvement Techniques, and Case Studies in Yield Improvement. Casting trials were conducted and then simulated using the precise casting conditions as recorded by the participating SFSA foundries. These results present a statistically meaningful set of experimental data on soundness versus feeding length. Comparisons between these casting trials and casting trials performed more than forty years ago by Pellini and the SFSA are quite good and appear reasonable. Comparisons between the current SFSA feeding rules and feeding rules based on the minimum Niyama criterion reveal that the Niyama-based rules are generally less conservative. The niyama-based rules also agree better with both the trials presented here, and the casting trails performed by Pellini an d the SFSA years ago. Furthermore, the use of the Niyama criterion to predict centerline shrinkage for horizontally fed plate sections has a theoretical basis according to the casting literature reviewed here. These results strongly support the use of improved feeding rules for horizontal plate sections based on the Niyama criterion, which can be tailored to the casting conditions for a given alloy and to a desired level of soundness. The reliability and repeatability of ASTM shrinkage x-ray ratings was investigated in a statistical study performed on 128 x-rays, each of which were rated seven different times. A manual ''Feeding and Risering Guidelines for Steel Castings' is given in this final report. Results of casting trials performed to test unconventional techniques for improving casting yield are presented. These use a stacked arrangement of castings and riser pressurization to increase the casting yield. Riser pressurization was demonstrated to feed a casting up to

  13. Linear atomic quantum coupler

    CERN Document Server

    El-Orany, Faisal A A

    2009-01-01

    In this paper, we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of them includes a localized and/or a trapped atom. These waveguides are placed close enough to allow exchanging energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way, i.e. as the Jaynes-Cummings model (JCM), and with the atom-mode in the second waveguide via evanescent wave. We present the Hamiltonian for the system and deduce the exact form for the wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional linear coupler, the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions, the system can yield the results of the two-m...

  14. Preparation of highly crystalline blue emitting MVO{sub 4}:Tm{sup 3+} (M=Gd, Y) spherical nanoparticles: Effects of activator concentration and annealing temperature on luminescence, lifetime and quantum yield

    Energy Technology Data Exchange (ETDEWEB)

    Shanta Singh, N. [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India); Ningthoujam, R.S., E-mail: rsn@barc.gov.i [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dorendrajit Singh, S., E-mail: dorendrajit@yahoo.co.i [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India); Viswanadh, B. [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Manoj, N. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Vatsa, R.K., E-mail: rkvatsa@barc.gov.i [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2010-12-15

    Highly crystalline spherical nanoparticles of MVO{sub 4}:Tm{sup 3+} (M=Gd, Y) having a size of 20-45 nm were prepared using ethylene glycol as both capping agent and reaction medium. X-ray diffraction study shows linear decrease in the unit cell volume with an increase in Tm{sup 3+} concentrations in MVO{sub 4} (M=Gd, Y; Tm{sup 3+}=0, 2, 5, 7, 10, 15, 20, 40, 60, 80 and 100 at%), indicative of quantitative substitution of Gd{sup 3+}/Y{sup 3+} lattice sites by Tm{sup 3+} ions in MVO{sub 4}. Blue light emission at 475 nm is observed after excitation at 310 nm due to energy transfer from VO{sub 4}{sup 3-} absorption band to Tm{sup 3+}. Emission intensity and average decay lifetime increase with an increase in heat treatment from 500 to 900 {sup o}C. This has been attributed to an extent of reduction in non-radiative process arising from surface. The emission intensity of Tm{sup 3+} in GdVO{sub 4} host is higher than that in YVO{sub 4} and thus the former host is better. Quantum yield increases with increase in heat-treatment temperature. This material will be the alternative blue light emitter.

  15. Facile Size-controllable Aqueous Synthesis of Water Soluble CdTe/Cd(OH)2 Core/Shell Nanoparticles with Tunable Optical Property, High Quantum Yield and Good Stability

    Institute of Scientific and Technical Information of China (English)

    CAI,Zhao-Xia; CHEN,Ying-Jun; YAN,Xiu-Ping

    2008-01-01

    A facile procedure was developed to prepare size-tunable and water soluble CdTe/Cd(OH)2 core/shell nanopar-ticles with high quantum yields and good stability using inexpensive inorganic precursors (CdCl2 and elemental Te). The emission colors of the prepared CdTe/Cd(OH)2 core/shell nanoparticles can be readily tuned from cyan to salmon pink by varying incubation time to control the growth of the Cd(OH)2 shell onto the CdTe nanoparticles. The CdTe/Cd(OH)2 core/shell nanoparticles were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction spectrometry, photoluminescence and UV-Vis spec-trometry. The good water-soluble nature of the CdTe/Cd(OH)2 core/shell nanoparticles offers great potentiality for their bio-labeling application. This approach is simple, mild and readily scaled up, affording a simple way for synthesis of size-tunable inorganic metal hydroxide capped core/shell nanoparticles.

  16. Spectral response of CuIn{sub 1-x}Ga{sub x}Se{sub 2} heterodiodes operated at constant V{sub OC} and constant I{sub SC} compared with traditionally recorded spectral quantum yield

    Energy Technology Data Exchange (ETDEWEB)

    Burdorf, Sven; Brueggemann, Rudolf; Bauer, Gottfried Heinrich [Institute of Physics, Carl von Ossietzky University Oldenburg (Germany)

    2009-07-01

    Traditional spectral response experiments in solar cells, such as quantum yields show the dependence of the excess carrier contribution and respective recombination on the depth of the device in terms of the profile of the optical generation. However, this depth information is masked by the condition of current continuity that is met by contributions of minority as well as majority carriers across the entire depth of the device and commonly the information on local properties is not reflected straightforwardly. In our approach - analogously to the concept of the constant photocurrent method (CPM) - we have adjusted either constant V{sub OC} (c-V{sub oc}) or I{sub SC} (c-I{sub sc}) by recording the spectral photon fluxes necessary for these conditions. In particular in V{sub oc} operation excess carriers recombine exclusively within the device and thus the signal is more sensitive against recombination. Our results of the c-V{sub oc} and c-I{sub sc} experiments for CIGSe-heterodiodes show significant differences particularly in the short-wavelength regimes. The comparison of experimental results with numerical modeling shows that this difference is growing larger with increasing interface recombination.

  17. Photocatalytic activity of transition-metal-ion-doped coordination polymer (CP): photoresponse region extension and quantum yields enhancement via doping of transition metal ions into the framework of CPs.

    Science.gov (United States)

    Xu, Xin-Xin; Cui, Zhong-Ping; Gao, Xin; Liu, Xiao-Xia

    2014-06-21

    To improve photocatalytic activity of a coordination polymer (CP) in the visible light region, five different transition metal ions (Fe(3+), Cr(3+), Ru(3+), Co(2+) and Ni(2+)) were introduced into its framework through an ion-exchange process. Among all the resulting transition metal ion doped coordination polymers (TMI/CPs), the one doped with Fe(3+) took on the most excellent photocatalytic activity and the highest quantum yields in the visible light region, decomposing 94% Rhodamine B (RhB) in 8 hours. It can be attributed to the doping of Fe(3+), which reduced the band gap (Eg) of the original CP, facilitating photocatalysis of the obtained polymer. Compared with the coordination polymer with Fe(3+) as a dopant, products doped with other metal ions presented weaker photocatalytic activities in the visible light region, while under the irradiation of ultraviolet light, they showed favorable photocatalytic properties. The results suggest that to dope transition metal ions into the framework of CPs would be an ideal option for enhancing the photocatalytic activity of coordination polymers.

  18. Revealing novel quantum phases in quantum antiferromagnets on random lattices

    Directory of Open Access Journals (Sweden)

    R. Yu

    2009-01-01

    Full Text Available Quantum magnets represent an ideal playground for the controlled realization of novel quantum phases and of quantum phase transitions. The Hamiltonian of the system can be indeed manipulated by applying a magnetic field or pressure on the sample. When doping the system with non-magnetic impurities, novel inhomogeneous phases emerge from the interplay between geometric randomness and quantum fluctuations. In this paper we review our recent work on quantum phase transitions and novel quantum phases realized in disordered quantum magnets. The system inhomogeneity is found to strongly affect phase transitions by changing their universality class, giving the transition a novel, quantum percolative nature. Such transitions connect conventionally ordered phases to unconventional, quantum disordered ones - quantum Griffiths phases, magnetic Bose glass phases - exhibiting gapless spectra associated with low-energy localized excitations.

  19. Thermal baths as quantum resources: more friends than foes?

    Science.gov (United States)

    Kurizki, Gershon; Shahmoon, Ephraim; Zwick, Analia

    2015-12-01

    In this article we argue that thermal reservoirs (baths) are potentially useful resources in processes involving atoms interacting with quantized electromagnetic fields and their applications to quantum technologies. One may try to suppress the bath effects by means of dynamical control, but such control does not always yield the desired results. We wish instead to take advantage of bath effects, that do not obliterate ‘quantumness’ in the system-bath compound. To this end, three possible approaches have been pursued by us. (i) Control of a quantum system faster than the correlation time of the bath to which it couples: such control allows us to reveal quasi-reversible/coherent dynamical phenomena of quantum open systems, manifest by the quantum Zeno or anti-Zeno effects (QZE or AZE, respectively). Dynamical control methods based on the QZE are aimed not only at protecting the quantumness of the system, but also diagnosing the bath spectra or transferring quantum information via noisy media. By contrast, AZE-based control is useful for fast cooling of thermalized quantum systems. (ii) Engineering the coupling of quantum systems to selected bath modes: this approach, based on field-atom coupling control in cavities, waveguides and photonic band structures, allows one to drastically enhance the strength and range of atom-atom coupling through the mediation of the selected bath modes. More dramatically, it allows us to achieve bath-induced entanglement that may appear paradoxical if one takes the conventional view that coupling to baths destroys quantumness. (iii) Engineering baths with appropriate non-flat spectra: this approach is a prerequisite for the construction of the simplest and most efficient quantum heat machines (engines and refrigerators). We may thus conclude that often thermal baths are ‘more friends than foes’ in quantum technologies.

  20. New Approach to Quantum Electrodynamics

    Directory of Open Access Journals (Sweden)

    Sze Kui Ng

    2008-04-01

    Full Text Available It is shown that a photon with a specific frequency can be identified with the Dirac magnetic monopole. When a Dirac-Wilson line forms a Dirac-Wilson loop, it is a photon. This loop model of photon is exactly solvable. From the winding numbers of this loop-form of photon, we derive the quantization properties of energy and electric charge. A new QED theory is presented that is free of ultravioletdivergences. The Dirac-Wilson line is as the quantum photon propagator of the new QED theory from which we can derive known QED effects such as the anomalous magnetic moment and the Lamb shift. The one-loop computation of these effects is simpler and is more accurate than that in the conventional QED theory. Furthermore, from the new QED theory, we have derived a new QED effect. A new formulation of the Bethe-Salpeter (BS equation solves the difficulties of the BS equation and gives a modified ground state of the positronium. By the mentioned new QED effect and by the new formulation of the BS equation, a term in the orthopositronium decay rate that is missing in the conventional QED is found, resolving the orthopositronium lifetime puzzle completely. It is also shown that the graviton can be constructed from the photon, yielding a theory of quantum gravity that unifies gravitation and electromagnetism.

  1. New Approach to Quantum Electrodynamics

    Directory of Open Access Journals (Sweden)

    Sze Kui Ng

    2008-04-01

    Full Text Available It is shown that a photon with a specific frequency can be identified with the Dirac mag- netic monopole. When a Dirac-Wilson line forms a Dirac-Wilson loop, it is a photon. This loop model of photon is exactly solvable. From the winding numbers of this loop- form of photon, we derive the quantization properties of energy and electric charge. A new QED theory is presented that is free of ultraviolet divergences. The Dirac-Wilson line is as the quantum photon propagator of the new QED theory from which we can derive known QED e ects such as the anomalous magnetic moment and the Lamb shift. The one-loop computation of these e ects is simpler and is more accurate than that in the conventional QED theory. Furthermore, from the new QED theory, we have derived a new QED e ect. A new formulation of the Bethe-Salpeter (BS equation solves the di culties of the BS equation and gives a modified ground state of the positronium. By the mentioned new QED e ect and by the new formulation of the BS equation, a term in the orthopositronium decay rate that is missing in the conventional QED is found, resolving the orthopositronium lifetime puzzle completely. It is also shown that the graviton can be constructed from the photon, yielding a theory of quantum gravity that unifies gravitation and electromagnetism.

  2. Quantum broadcast channels

    CERN Document Server

    Yard, J; Devetak, I; Yard, Jon; Hayden, Patrick; Devetak, Igor

    2006-01-01

    We analyze quantum broadcast channels, which are quantum channels with a single sender and many receivers. Focusing on channels with two receivers for simplicity, we generalize a number of results from the network Shannon theory literature which give the rates at which two senders can receive a common message, while a personalized one is sent to one of them. Our first collection of results applies to channels with a classical input and quantum outputs. The second class of theorems we prove concern sending a common classical message over a quantum broadcast channel, while sending quantum information to one of the receivers. The third group of results we obtain concern communication over an isometry, giving the rates at quantum information can be sent to one receiver, while common quantum information is sent to both, in the sense that tripartite GHZ entanglement is established. For each scenario, we provide an additivity proof for an appropriate class of channels, yielding single-letter characterizations of the...

  3. Efectos de sistemas parciales de agricultura biológica y convencional (local en la fertilidad de suelos y en la producción de frijol en Villanueva (Santander, Colombia. Ciclo II Effects of organic and conventional partial farming system on soil fertility and bean yield in Villanueva (Santander, Colombia

    Directory of Open Access Journals (Sweden)

    León Sicard Tomás Enrique

    1998-12-01

    Full Text Available Se comparó el efecto en la fertilidad del suelo y en la producción de fríjol (Phaseolus vulgaris x millo (Sorghum sp. de sistemas parciales de agricultura biológica y convencional (local, durante 3 semestres (1995A-1996A, utilizando un arreglo de parcelas divididas y un diseño en bloques completos al azar con 3 replicaciones, en el que la Parcela Mayor fue el tipo de manejo de plagas (biológico o químico, la Subparcela fue el arreglo de cultivo (asocio vs cultivo y la Sub-subparcela fue el tipo de fertilización química vs abonamiento orgánico. En ninguno de los tres semestres se presentaron diferencias significativas entre los rendimientos de fríjol por efecto de los tipos de agricultura, confirmando resultados anteriores de 1994A y B. Durante 1995B, los rendimientos del millo fueron significativamente superiores en el sistema biológico, debido probablemente, a efectos edáficos. Los Indices de Uso Eficiente de la Tierra (IET fueron superiores a 1 en toda la experiencia, indicando el efecto positivo del asocio. Se constataron incrementos en acidez, capacidad de intercambio catiónico, bases totales y saturación total del suelo en todas las parcelas, que incidieron para que su fertilidad global aumentara de baja a moderada.
    The effects of organic versus conventional farming methods in soil fertility and intercropping yields (Phaseolus vulgaris x Sorghum sp. was studied throughout three growing seasons (1995A-1996A. The methodoly used to conduct the study was to divide the field into parcels, aplying natural vs chemical disease controls, monoculture vs intercropping and manure vs chemical fertilizers. As well as other experience carried out in 1994, neither bean growing season presented significant differences between the two agricultural systems, although the yield of sorghum in the organic farming system was superior to that of the conventional system during 1995B, probably due to edaphic effects. The Efficient Land Use Index

  4. Comparative Study on Yield Formation and Nutrient Uptake and Utilization between Super Hybrid Rice and Conventional Rice%超级杂交稻与常规稻产量形成及养分吸收利用的比较研究

    Institute of Scientific and Technical Information of China (English)

    夏冰; 蒋鹏; 谢小兵; 赵杨; 魏颖娟; 黄敏; 邹应斌

    2015-01-01

    To ascertain the characteristics of yield formation, dry matter production and the nutrient uptake and utilization of nitrogen (N), phosphorus(P) and potassium(K) between super hybrid rice and conventional rice, taking similar panicles size of super hybrid rice(Liangyou peijiu, Y Liangyou 1) and conventional rice(Huanghuazhan, Yuxiangyouzhan) as materials, the field experiment with high N level(225(kg/hm2), medium N level(113~161 kg/hm2), and no N level(0 kg/hm2) was conducted in Changsha(N 28°12′) from 2011 to 2013. The results showed that super hybrid rice yield in average 9.55 and 9.57 t/hm 2 rice grains, produced averagely 18.05 and 18.24 t/hm2 dry matter and assimilated averagely 189.5 and 193.9 kg/hm2 N at maturity stage, of which increased signifi-cantly by 5.99%and 9.38%, 7.12%and 11.22%, 5.45%and 4.41% compared with conventional rice, respectively. Both super hybrid rice and conventional rice showed the nonlinear relationship of quadratic function between the grain yield and the N, P, K uptake rates and the multiple correlation coefficient was significant. Requirements for N, P and K of super hybrid rice were up to 19.79 and 20.09 kg, 3.90 and 4.09 kg, 20.57 and 22.37 kg, respectively, of which was significantly lower than that of conventional varieties. Un-der the condition of nitrogen application, there was a significantly linear correlation between the grain yield and the N, P, K nutrient requirements. Nitrogen recovery efficiency and its partial productivity showed the significant difference among tested varieties, but the agronomy efficiency and physiological utilization efficiency did not show the significant difference among the varieties. Nitrogen har-vest index of super hybrid rice was as high as 68.6% and 69.1% and significantly higher than that of conventional rice (62.7% and 64.0%), but no significant difference of N grain production efficiency was observed among the varieties. It is concluded that the high-yielding super hybrid rice was

  5. A kinetic model for evaluating the dependence of the quantum yield of nano-TiO{sub 2} based photocatalysis on light intensity, grain size, carrier lifetime, and minority carrier diffusion coefficient: Indirect interfacial charge transfer

    Energy Technology Data Exchange (ETDEWEB)

    Liu Baoshun, E-mail: liubaoshun@126.co [Key Laboratory of Silicate Materials Science and Engineering, Ministry of Education, Wuhan, Hubei 430070 (China) and School of Material Science and Technology, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Zhao Xiujian [Key Laboratory of Silicate Materials Science and Engineering, Ministry of Education, Wuhan, Hubei 430070 (China)

    2010-04-30

    A model based on spherical TiO{sub 2} nanoparticles was developed to study heterogeneous photocatalysis based on TiO{sub 2} in the case of indirect interfacial charge transfer. In this model, the effect of light intensity (I{sub 0}), grain size (r{sub 0}), carrier lifetime (tau{sub p}), and minority carrier diffusion coefficient (D{sub p}) on the quantum yield (QY) of photocatalytic reactions was investigated in detail. Under conditions of sufficiently low incident-light intensity, the QY was found to be propor toI{sub 0}, while it decreased rapidly with an increase in I{sub 0}. In addition, the QY went to zero at a critically high light intensity. Furthermore, the QY was found to decrease with increasing r{sub 0} due to the bulk-recombination loss, and the effect of r{sub 0} on the QY became increasingly stronger with the increase in I{sub 0}. The QY decreased with the decrease in tau{sub p} and D{sub p}, which was more apparent at the critically high I{sub 0}. Under conditions of low [(RH{sub 2}){sub aq}], the QY increased with an increase in [(RH{sub 2}){sub aq}], while it remained nearly constant at high [(RH{sub 2}){sub aq}] due to the fact that the photoinduced electron interfacial transfer became the limiting step for photocatalytic reactions in the case of high [(RH{sub 2}){sub aq}].

  6. Quantum computing of semiclassical formulas.

    Science.gov (United States)

    Georgeot, B; Giraud, O

    2008-04-01

    We show that semiclassical formulas such as the Gutzwiller trace formula can be implemented on a quantum computer more efficiently than on a classical device. We give explicit quantum algorithms which yield quantum observables from classical trajectories, and which alternatively test the semiclassical approximation by computing classical actions from quantum evolution. The gain over classical computation is in general quadratic, and can be larger in some specific cases.

  7. The Hague Judgments Convention

    DEFF Research Database (Denmark)

    Nielsen, Peter Arnt

    2011-01-01

    The Hague Judgments Convention of 2005 is the first global convention on international jurisdiction and recognition and enforcement of judgments in civil and commercial matters. The author explains the political and legal background of the Convention, its content and certain crucial issues during...

  8. Adiabatic Quantum Computation is Equivalent to Standard Quantum Computation

    CERN Document Server

    Aharonov, D; Kempe, J; Landau, Z; Lloyd, S; Regev, O; Aharonov, Dorit; Dam, Wim van; Kempe, Julia; Landau, Zeph; Lloyd, Seth; Regev, Oded

    2004-01-01

    Adiabatic quantum computation has recently attracted attention in the physics and computer science communities, but its computational power has been unknown. We settle this question and describe an efficient adiabatic simulation of any given quantum algorithm, which implies that the adiabatic computation model and the conventional quantum circuit model are polynomially equivalent. Our result can be extended to the physically realistic setting of particles arranged on a two-dimensional grid with nearest neighbor interactions. The equivalence between the models provides a new vantage point from which to tackle the central issues in quantum computation, namely designing new quantum algorithms and constructing fault tolerant quantum computers. In particular, by translating the main open questions in quantum algorithms to the language of spectral gaps of sparse matrices, the result makes quantum algorithmic questions accessible to a wider scientific audience, acquainted with mathematical physics, expander theory a...

  9. Extended renormalizations group analysis for quantum gravity and Newton's gravitational constant

    Energy Technology Data Exchange (ETDEWEB)

    El Naschie, M.S. [Department of Physics, University of Alexandria (Egypt); Donghua University, Shanghai (China)], E-mail: Chaossf@aol.com

    2008-02-15

    The conventional renormalization groups as applied in SU(5) GUT are adapted to the transfinite simplictic arithmetic of E-infinity theory. The resulting simple formalism yielded the exact quantum gravity inverse coupling for non-super symmetric and super symmetric unifications alike. Subsequently by means of analogy supported by Witten's T-duality and black hole theory an accurate estimation of Newton's constant of gravity is derived from what is basically the same formalism.

  10. Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae

    Directory of Open Access Journals (Sweden)

    Bascuñán-Godoy Luisa

    2012-07-01

    Full Text Available Abstract Background Ecotypes of Colobanthus quitensis Kunt Bartl (Cariophyllaceae from Andes Mountains and Maritime Antarctic grow under contrasting photoinhibitory conditions, reaching differential cold tolerance upon cold acclimation. Photoinhibition depends on the extent of photodamage and recovery capability. We propose that cold acclimation increases resistance to low-temperature-induced photoinhibition, limiting photodamage and promoting recovery under cold. Therefore, the Antarctic ecotype (cold hardiest should be less photoinhibited and have better recovery from low-temperature-induced photoinhibition than the Andean ecotype. Both ecotypes were exposed to cold induced photoinhibitory treatment (PhT. Photoinhibition and recovery of photosystem II (PSII was followed by fluorescence, CO2 exchange, and immunoblotting analyses. Results The same reduction (25% in maximum PSII efficiency (Fv/Fm was observed in both cold-acclimated (CA and non-acclimated (NA plants under PhT. A full recovery was observed in CA plants of both ecotypes under dark conditions, but CA Antarctic plants recover faster than the Andean ecotype. Under PhT, CA plants maintain their quantum yield of PSII, while NA plants reduced it strongly (50% and 73% for Andean and Antarctic plants respectively. Cold acclimation induced the maintenance of PsaA and Cyt b6/f and reduced a 41% the excitation pressure in Antarctic plants, exhibiting the lowest level under PhT. xCold acclimation decreased significantly NPQs in both ecotypes, and reduced chlorophylls and D1 degradation in Andean plants under PhT. NA and CA plants were able to fully restore their normal photosynthesis, while CA Antarctic plants reached 50% higher photosynthetic rates after recovery, which was associated to electron fluxes maintenance under photoinhibitory conditions. Conclusions Cold acclimation has a greater importance on the recovery process than on limiting photodamage. Cold acclimation determined the

  11. Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae).

    Science.gov (United States)

    Bascuñán-Godoy, Luisa; Sanhueza, Carolina; Cuba, Marely; Zuñiga, Gustavo E; Corcuera, Luis J; Bravo, León A

    2012-07-24

    Ecotypes of Colobanthus quitensis Kunt Bartl (Cariophyllaceae) from Andes Mountains and Maritime Antarctic grow under contrasting photoinhibitory conditions, reaching differential cold tolerance upon cold acclimation. Photoinhibition depends on the extent of photodamage and recovery capability. We propose that cold acclimation increases resistance to low-temperature-induced photoinhibition, limiting photodamage and promoting recovery under cold. Therefore, the Antarctic ecotype (cold hardiest) should be less photoinhibited and have better recovery from low-temperature-induced photoinhibition than the Andean ecotype. Both ecotypes were exposed to cold induced photoinhibitory treatment (PhT). Photoinhibition and recovery of photosystem II (PSII) was followed by fluorescence, CO2 exchange, and immunoblotting analyses. The same reduction (25%) in maximum PSII efficiency (Fv/Fm) was observed in both cold-acclimated (CA) and non-acclimated (NA) plants under PhT. A full recovery was observed in CA plants of both ecotypes under dark conditions, but CA Antarctic plants recover faster than the Andean ecotype.Under PhT, CA plants maintain their quantum yield of PSII, while NA plants reduced it strongly (50% and 73% for Andean and Antarctic plants respectively). Cold acclimation induced the maintenance of PsaA and Cyt b6/f and reduced a 41% the excitation pressure in Antarctic plants, exhibiting the lowest level under PhT. xCold acclimation decreased significantly NPQs in both ecotypes, and reduced chlorophylls and D1 degradation in Andean plants under PhT.NA and CA plants were able to fully restore their normal photosynthesis, while CA Antarctic plants reached 50% higher photosynthetic rates after recovery, which was associated to electron fluxes maintenance under photoinhibitory conditions. Cold acclimation has a greater importance on the recovery process than on limiting photodamage. Cold acclimation determined the kinetic and extent of recovery process under darkness in

  12. Quantum corrections for Boltzmann equation

    Institute of Scientific and Technical Information of China (English)

    M.; Levy; PETER

    2008-01-01

    We present the lowest order quantum correction to the semiclassical Boltzmann distribution function,and the equation satisfied by this correction is given. Our equation for the quantum correction is obtained from the conventional quantum Boltzmann equation by explicitly expressing the Planck constant in the gradient approximation,and the quantum Wigner distribution function is expanded in pow-ers of Planck constant,too. The negative quantum correlation in the Wigner dis-tribution function which is just the quantum correction terms is naturally singled out,thus obviating the need for the Husimi’s coarse grain averaging that is usually done to remove the negative quantum part of the Wigner distribution function. We also discuss the classical limit of quantum thermodynamic entropy in the above framework.

  13. Varieties of conventional implicature

    Directory of Open Access Journals (Sweden)

    Eric Scott McCready

    2010-07-01

    Full Text Available This paper provides a system capable of analyzing the combinatorics of a wide range of conventionally implicated and expressive constructions in natural language via an extension of Potts's (2005 L_CI logic for supplementary conventional implicatures. In particular, the system is capable of analyzing objects of mixed conventionally implicated/expressive and at-issue type, and objects with conventionally implicated or expressive meanings which provide the main content of their utterances. The logic is applied to a range of constructions and lexical items in several languages. doi:10.3765/sp.3.8 BibTeX info

  14. Quantum computing

    OpenAIRE

    Li, Shu-Shen; Long, Gui-lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi

    2001-01-01

    Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization.

  15. 控释尿素与常规尿素不同配施对根际土壤微生物数目、土壤氮素及玉米产量的影响%Effects of Controlled-release Urea Combined with Conventional Urea on Rhizosphere Soil Microorganisms , Soil Nitrogen and Yield of Maize

    Institute of Scientific and Technical Information of China (English)

    孟庆英; 朱宝国; 王囡囡; 贾会彬; 于忠和; 张春峰

    2012-01-01

    为研究控释尿素与常规尿素配施条件下对玉米根际土壤微生物的影响,采用不同肥料配比处理,对玉米根际土壤细菌、真菌、放线菌采用平板计数法进行数量测定;对玉米成熟期根际土壤微生物数量变化、土壤氮素含量变化及玉米产量相关因素进行研究,结果表明控释尿素与常规尿素不同配施条件下,与CK相比施用肥料的各个处理,土壤微生物数量均增加,CRU100%处理有利于增加土壤细菌、土壤氮素含量及玉米产量,CRU40%+PU60%处理在增加土壤真菌及放线菌数量上优于其他配比。针对实际生产应用及对土壤微生物整体影响,综合比较本研究表明CRU40%+PU60%处理为最佳配比并为控释尿素与常规尿素配施条件下土壤微生物生态环境的深入研究提供依据。%Abstract: The objective of current study was to investigate the effects of controlled-release urea combined with conventional urea on rhizosphere soil microorganisms of maize. The numbers of bacteria, fungi, actinomycetes of rtizosphere soil were determined through colony counting method. The research included the effects of different fertilizers treatments on the changes of rhizosphere soil microorganisms of maize, nitrogen content of soil, yield and yieht components of maize at maturity. The results showed that effects of controlled-release urea combined with conventional urea on the number of microorganisms of soil were different. Compared with CK treatment, the amounts of miroorganisms in fertilizer treatments were higher. The CRU100% treatment improved of nitrogen content of soil and yield of maize. CRU40%+PU60% had higher value on the number of fungi and actinomycetes. According to the praetical production and application and the overall effects on the soil microorganisms, the research of comprehensive comparison showed that CRU40%+PU60% was the optimum proportion, and the study provided evidence

  16. Local, nonlocal quantumness and information theoretic measures

    Science.gov (United States)

    Agrawal, Pankaj; Sazim, Sk; Chakrabarty, Indranil; Pati, Arun K.

    2016-08-01

    It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by information theoretic quantities such as quantum discord, but not by the conventional measures of entanglement. We argue that a state displays quantumness, that can be of local and nonlocal origin. Information theoretic measures not only characterize the nonlocal quantumness, but also the local quantumness, such as the “local superposition”. This can be a reason, why such measures are nonzero, when there is no entanglement. We consider a generalized version of the Werner state to demonstrate the interplay of local quantumness, nonlocal quantumness and classical mixedness of a state.

  17. Quantum Spin Hall Effect

    Energy Technology Data Exchange (ETDEWEB)

    Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-01-15

    The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.

  18. Quantum Distinction: Quantum Distinctiones!

    OpenAIRE

    Zeps, Dainis

    2009-01-01

    10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...

  19. Generalized Geometric Quantum Speed Limits

    Science.gov (United States)

    Pires, Diego Paiva; Cianciaruso, Marco; Céleri, Lucas C.; Adesso, Gerardo; Soares-Pinto, Diogo O.

    2016-04-01

    The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.

  20. Generalized Geometric Quantum Speed Limits

    Directory of Open Access Journals (Sweden)

    Diego Paiva Pires

    2016-06-01

    Full Text Available The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We investigate how the nonuniqueness of a bona fide measure of distinguishability defined on the quantum-state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for unitary and nonunitary evolutions, based on an elegant information geometric formalism. Our work unifies and generalizes existing results on quantum speed limits and provides instances of novel bounds that are tighter than any established one based on the conventional quantum Fisher information. We illustrate our findings with relevant examples, demonstrating the importance of choosing different information metrics for open system dynamics, as well as clarifying the roles of classical populations versus quantum coherences, in the determination and saturation of the speed limits. Our results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.

  1. Embracing the quantum limit in silicon computing.

    Science.gov (United States)

    Morton, John J L; McCamey, Dane R; Eriksson, Mark A; Lyon, Stephen A

    2011-11-16

    Quantum computers hold the promise of massive performance enhancements across a range of applications, from cryptography and databases to revolutionary scientific simulation tools. Such computers would make use of the same quantum mechanical phenomena that pose limitations on the continued shrinking of conventional information processing devices. Many of the key requirements for quantum computing differ markedly from those of conventional computers. However, silicon, which plays a central part in conventional information processing, has many properties that make it a superb platform around which to build a quantum computer.

  2. A linear atomic quantum coupler

    Energy Technology Data Exchange (ETDEWEB)

    El-Orany, Faisal A A [Department of Mathematics and computer Science, Faculty of Science, Suez Canal University 41522, Ismailia (Egypt); Wahiddin, M R B, E-mail: el_orany@hotmail.co, E-mail: faisal.orany@mimos.m, E-mail: mridza@mimos.m [Cyberspace Security Laboratory, MIMOS Berhad, Technology Park Malaysia, 57000 Kuala Lumpur (Malaysia)

    2010-04-28

    In this paper we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of which includes a localized atom. These waveguides are placed close enough to allow exchange of energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way as the Jaynes-Cummings model (JCM) and with the atom-mode system in the second waveguide via the evanescent wave. We present the Hamiltonian for this system and deduce its wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional coupler the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit a long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions the system can yield the results of the two-mode JCM.

  3. N-acetylcysteine increased rice yield

    OpenAIRE

    NOZULAIDI, MOHD; JAHAN, MD SARWAR; KHAIRI, MOHD; Khandaker, Mohammad Moneruzzaman; Mat NASHRIYAH; KHANIF, YUSOP MOHD

    2015-01-01

    N-acetylcysteine (NAC) biosynthesized reduced glutathione (GSH), which maintains redox homeostasis in plants under normal and stressful conditions. To justify the effects of NAC on rice production, we measured yield parameters, chlorophyll (Chl) content, minimum Chl fluorescence (Fo), maximum Chl fluorescence (Fm), quantum yield (Fv/Fm), net photosynthesis rate (Pn), photosynthetically active radiation (PAR), and relative water content (RWC). Four treatments, N1G0 (nitrogen (N) with no NAC), ...

  4. The Geometry of Conventionality

    CERN Document Server

    Weatherall, James Owen

    2013-01-01

    Hans Reichenbach famously argued that the geometry of spacetime is conventional in relativity theory, in the sense that one can freely choose the spacetime metric so long as one is willing to postulate a "universal force field". Here we make precise a sense in which the field Reichenbach defines fails to be a "force". We then argue that there is an interesting and perhaps tenable sense in which geometry is conventional in classical spacetimes. We conclude with a no-go result showing that the variety of conventionalism available in classical spacetimes does not extend to relativistic spacetimes.

  5. Undoing a quantum measurement.

    Science.gov (United States)

    Schindler, Philipp; Monz, Thomas; Nigg, Daniel; Barreiro, Julio T; Martinez, Esteban A; Brandl, Matthias F; Chwalla, Michael; Hennrich, Markus; Blatt, Rainer

    2013-02-15

    In general, a quantum measurement yields an undetermined answer and alters the system to be consistent with the measurement result. This process maps multiple initial states into a single state and thus cannot be reversed. This has important implications in quantum information processing, where errors can be interpreted as measurements. Therefore, it seems that it is impossible to correct errors in a quantum information processor, but protocols exist that are capable of eliminating them if they affect only part of the system. In this work we present the deterministic reversal of a fully projective measurement on a single particle, enabled by a quantum error-correction protocol in a trapped ion quantum information processor. We further introduce an in-sequence, single-species recooling procedure to counteract the motional heating of the ion string due to the measurement.

  6. Conventional Spinal Anaesthesia

    African Journals Online (AJOL)

    patients scheduled for clcctive unilateral lower limb surgery. ... the conventional group were turned supine immediately after injection. Blood pressure, heart rate, respiratory rate and oxygen .... Characteristic Type of spinal anaesthcsia P-value.

  7. Simulating chemistry using quantum computers

    CERN Document Server

    Kassal, Ivan; Perdomo-Ortiz, Alejandro; Yung, Man-Hong; Aspuru-Guzik, Alán

    2010-01-01

    The difficulty of simulating quantum systems, well-known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.

  8. Simulating chemistry using quantum computers.

    Science.gov (United States)

    Kassal, Ivan; Whitfield, James D; Perdomo-Ortiz, Alejandro; Yung, Man-Hong; Aspuru-Guzik, Alán

    2011-01-01

    The difficulty of simulating quantum systems, well known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.

  9. Tests and prospects of new physics at very high energy. Beyond the standard basic principles, and beyond conventional matter and space-time. On the possible origin of Quantum Mechanics.

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres Luis

    2015-01-01

    Full Text Available Recent results and announcements by Planck and BICEP2 have led to important controversies in the fields of Cosmology and Particle Physics. As new ideas and alternative approaches can since then more easily emerge, the link between the Mathematical Physics aspects of theories and the interpretation of experimental results becomes more direct. This evolution is also relevant for Particle Physics experiments at very high energy, where the interpretation of data on the highest-energy cosmic rays remains a major theoretical and phenomenological challenge. Alternative particle physics and cosmology can raise fundamental questions such as that of the structure of vacuum and space-time. In particular, the simplified description of the physical vacuum contained in standard quantum field theory does not necessarily correspond to reality at a deeper level, and similarly for the relativistic space-time based on four real variables. In a more general approach, the definition itself of vacuum can be a difficult task. The spinorial space-time (SST we suggested in 1996-97 automatically incorporates a local privileged space direction (PSD for each comoving observer, possibly leading to a locally anisotropic vacuum structure. As the existence of the PSD may have been confirmed by Planck, and a possible discovery of primordial B-modes in the polarization of the cosmic microwave background radiation (CMB may turn out to contain new evidence for the SST, we explore other possible implications of this approach to space-time. The SST structure can naturally be at the origin of Quantum Mechanics at distance scales larger than the fundamental one if standard particles are dealt with as vacuum excitations. We also discuss possible implications of our lack of knowledge of the structure of vacuum, as well as related theoretical, phenomenological and cosmological uncertainties. Pre-Big Bang scenarios and new ultimate constituents of matter (including superbradyons are

  10. Tests and prospects of new physics at very high energy. Beyond the standard basic principles, and beyond conventional matter and space-time. On the possible origin of Quantum Mechanics.

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres Luis

    2015-01-01

    Full Text Available Recent results and announcements by Planck and BICEP2 have led to important controversies in the fields of Cosmology and Particle Physics. As new ideas and alternative approaches can since then more easily emerge, the link between the Mathematical Physics aspects of theories and the interpretation of experimental results becomes more direct. This evolution is also relevant for Particle Physics experiments at very high energy, where the interpretation of data on the highest-energy cosmic rays remains a major theoretical and phenomenological challenge. Alternative particle physics and cosmology can raise fundamental questions such as that of the structure of vacuum and space-time. In particular, the simplified description of the physical vacuum contained in standard quantum field theory does not necessarily correspond to reality at a deeper level, and similarly for the relativistic space-time based on four real variables. In a more general approach, the definition itself of vacuum can be a difficult task. The spinorial space-time (SST we suggested in 1996-97 automatically incorporates a local privileged space direction (PSD for each comoving observer, possibly leading to a locally anisotropic vacuum structure. As the existence of the PSD may have been confirmed by Planck, and a possible discovery of primordial B-modes in the polarization of the cosmic microwave background radiation (CMB may turn out to contain new evidence for the SST, we explore other possible implications of this approach to space-time. The SST structure can naturally be at the origin of Quantum Mechanics at distance scales larger than the fundamental one if standard particles are dealt with as vacuum excitations. We also discuss possible implications of our lack of knowledge of the structure of vacuum, as well as related theoretical, phenomenological and cosmological uncertainties. Pre-Big Bang scenarios and new ultimate constituents of matter (including superbradyons are

  11. Quantum anonymous voting with unweighted continuous-variable graph states

    Science.gov (United States)

    Guo, Ying; Feng, Yanyan; Zeng, Guihua

    2016-08-01

    Motivated by the revealing topological structures of continuous-variable graph state (CVGS), we investigate the design of quantum voting scheme, which has serious advantages over the conventional ones in terms of efficiency and graphicness. Three phases are included, i.e., the preparing phase, the voting phase and the counting phase, together with three parties, i.e., the voters, the tallyman and the ballot agency. Two major voting operations are performed on the yielded CVGS in the voting process, namely the local rotation transformation and the displacement operation. The voting information is carried by the CVGS established before hand, whose persistent entanglement is deployed to keep the privacy of votes and the anonymity of legal voters. For practical applications, two CVGS-based quantum ballots, i.e., comparative ballot and anonymous survey, are specially designed, followed by the extended ballot schemes for the binary-valued and multi-valued ballots under some constraints for the voting design. Security is ensured by entanglement of the CVGS, the voting operations and the laws of quantum mechanics. The proposed schemes can be implemented using the standard off-the-shelf components when compared to discrete-variable quantum voting schemes attributing to the characteristics of the CV-based quantum cryptography.

  12. Performance of a Single Quantum Neuron

    Institute of Scientific and Technical Information of China (English)

    LIFei; ZHAOShengmei; ZHENGBaoyu

    2005-01-01

    Quantum neural network (QNN) is a promising area in the field of quantum computing and quantum information processing. A novel model for quantum neuron is described, a quantum learning algorithm is proposed and its convergence property is investigated. It has been shown, Quantum neuron (QN) has the same convergence property as Conventional neuron (CN) but can attain faster training than Conventional neuron. The computational power of the quantum neuron is also explored.Numerical and graphical results show that this single quantum neuron can implement the Walsh-Hadamard transformation, perform the XOR function unrealizable with a classical neuron and can eliminate the necessity of building a network of neurons to obtain nonlinear mapping.

  13. Low-Yield Cigarettes

    Science.gov (United States)

    ... Program Division of Reproductive Health More CDC Sites Low-Yield Cigarettes Recommend on Facebook Tweet Share Compartir ... they compensate when smoking them. Smokers Who Use Low-Yield Cigarettes Many smokers consider smoking low-yield ...

  14. Semiclassical genetic algorithm with quantum crossover and mutation operations

    CERN Document Server

    SaiToh, Akira; Nakahara, Mikio

    2012-01-01

    In order for finding a good individual for a given fitness function in the context of evolutionary computing, we introduce a novel semiclassical quantum genetic algorithm. It has both of quantum crossover and quantum mutation procedures unlike conventional quantum genetic algorithms. A complexity analysis shows a certain improvement over its classical counterpart.

  15. Strange attractor simulated on a quantum computer

    OpenAIRE

    2002-01-01

    We show that dissipative classical dynamics converging to a strange attractor can be simulated on a quantum computer. Such quantum computations allow to investigate efficiently the small scale structure of strange attractors, yielding new information inaccessible to classical computers. This opens new possibilities for quantum simulations of various dissipative processes in nature.

  16. Experimental quantum multiparty communication protocols

    Science.gov (United States)

    Smania, Massimiliano; Elhassan, Ashraf M.; Tavakoli, Armin; Bourennane, Mohamed

    2016-06-01

    Quantum information science breaks limitations of conventional information transfer, cryptography and computation by using quantum superpositions or entanglement as resources for information processing. Here we report on the experimental realisation of three-party quantum communication protocols using single three-level quantum system (qutrit) communication: secret-sharing, detectable Byzantine agreement and communication complexity reduction for a three-valued function. We have implemented these three schemes using the same optical fibre interferometric setup. Our realisation is easily scalable without compromising on detection efficiency or generating extremely complex many-particle entangled states.

  17. Symmetry and Covariance of Non-relativistic Quantum Mechanics

    OpenAIRE

    Omote, Minoru; kamefuchi, Susumu

    2000-01-01

    On the basis of a 5-dimensional form of space-time transformations non-relativistic quantum mechanics is reformulated in a manifestly covariant manner. The resulting covariance resembles that of the conventional relativistic quantum mechanics.

  18. Quantum stochastics

    CERN Document Server

    Chang, Mou-Hsiung

    2015-01-01

    The classical probability theory initiated by Kolmogorov and its quantum counterpart, pioneered by von Neumann, were created at about the same time in the 1930s, but development of the quantum theory has trailed far behind. Although highly appealing, the quantum theory has a steep learning curve, requiring tools from both probability and analysis and a facility for combining the two viewpoints. This book is a systematic, self-contained account of the core of quantum probability and quantum stochastic processes for graduate students and researchers. The only assumed background is knowledge of the basic theory of Hilbert spaces, bounded linear operators, and classical Markov processes. From there, the book introduces additional tools from analysis, and then builds the quantum probability framework needed to support applications to quantum control and quantum information and communication. These include quantum noise, quantum stochastic calculus, stochastic quantum differential equations, quantum Markov semigrou...

  19. Quantum Computing

    CERN Document Server

    Steane, A M

    1998-01-01

    The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. This review aims to summarise not just quantum computing, but the whole subject of quantum information theory. It turns out that information theory and quantum mechanics fit together very well. In order to explain their relationship, the review begins with an introduction to classical information theory and computer science, including Shannon's theorem, error correcting codes, Turing machines and computational complexity. The principles of quantum mechanics are then outlined, and the EPR experiment described. The EPR-Bell correlations, and quantum entanglement in general, form the essential new ingredient which distinguishes quantum from classical information theory, and, arguably, quantum from classical physics. Basic quantum information ideas are described, including key distribution, teleportation, data compression, quantum error correction, the universal quantum computer and qua...

  20. Quantum Blobs

    OpenAIRE

    Gosson, Maurice A. de

    2012-01-01

    Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level set...

  1. Quantum many-body simulation using monolayer exciton-polaritons in coupled-cavities.

    Science.gov (United States)

    Wang, Hai-Xiao; Zhan, Alan; Xu, Yadong; Chen, Huanyang; You, Wen-Long; Majumdar, Arka; Jiang, JianHua

    2017-08-30

    Quantum simulation is a promising approach to understand complex strongly correlated many-body systems using relatively simple and tractable systems. Photon-based quantum simulators have great advantages due to the possibility of direct measurements of multi-particle correlations and ease of simulating non-equilibrium physics. However, interparticle interaction in existing photonic systems is often too weak limiting the potential of quantum simulation. Here we propose an approach to enhance the interparticle interaction using exciton-polaritons in MoS$_2$ monolayer quantum-dots embedded in 2D photonic crystal microcavities. Realistic calculation yields optimal repulsive interaction in the range of $1$-$10$~meV --- more than an order of magnitude greater than the state-of-art value. Such strong repulsive interaction is found to emerge neither in the photon-blockade regime for small quantum dot nor in the polariton-blockade regime for large quantum dot, but in the crossover between the two regimes with a moderate quantum-dot radius around 20~nm. The optimal repulsive interaction is found to be largest in MoS$_2$ among commonly used optoelectronic materials. Quantum simulation of strongly correlated many-body systems in a finite chain of coupled cavities and its experimental signature are studied via exact diagonalization of the many-body Hamiltonian. A method to simulate 1D superlattices for interacting exciton-polariton gases in serially coupled cavities is also proposed. Realistic considerations on experimental realizations reveal advantages of transition metal dichalcogenide monolayer quantum-dots over conventional semiconductor quantum-emitters. © 2017 IOP Publishing Ltd.

  2. Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

    OpenAIRE

    Kröger, H.

    2003-01-01

    We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

  3. Nonlinear Dynamics In Quantum Physics -- Quantum Chaos and Quantum Instantons

    OpenAIRE

    Kröger, H.

    2003-01-01

    We discuss the recently proposed quantum action - its interpretation, its motivation, its mathematical properties and its use in physics: quantum mechanical tunneling, quantum instantons and quantum chaos.

  4. Quantum dynamics of simultaneously measured non-commuting observables

    Science.gov (United States)

    Hacohen-Gourgy, Shay; Martin, Leigh S.; Flurin, Emmanuel; Ramasesh, Vinay V.; Whaley, K. Birgitta; Siddiqi, Irfan

    2016-10-01

    In quantum mechanics, measurements cause wavefunction collapse that yields precise outcomes, whereas for non-commuting observables such as position and momentum Heisenberg’s uncertainty principle limits the intrinsic precision of a state. Although theoretical work has demonstrated that it should be possible to perform simultaneous non-commuting measurements and has revealed the limits on measurement outcomes, only recently has the dynamics of the quantum state been discussed. To realize this unexplored regime, we simultaneously apply two continuous quantum non-demolition probes of non-commuting observables to a superconducting qubit. We implement multiple readout channels by coupling the qubit to multiple modes of a cavity. To control the measurement observables, we implement a ‘single quadrature’ measurement by driving the qubit and applying cavity sidebands with a relative phase that sets the observable. Here, we use this approach to show that the uncertainty principle governs the dynamics of the wavefunction by enforcing a lower bound on the measurement-induced disturbance. Consequently, as we transition from measuring identical to measuring non-commuting observables, the dynamics make a smooth transition from standard wavefunction collapse to localized persistent diffusion and then to isotropic persistent diffusion. Although the evolution of the state differs markedly from that of a conventional measurement, information about both non-commuting observables is extracted by keeping track of the time ordering of the measurement record, enabling quantum state tomography without alternating measurements. Our work creates novel capabilities for quantum control, including rapid state purification, adaptive measurement, measurement-based state steering and continuous quantum error correction. As physical systems often interact continuously with their environment via non-commuting degrees of freedom, our work offers a way to study how notions of contemporary

  5. Colloidal quantum dots: synthesis, properties and applications

    Science.gov (United States)

    Brichkin, S. B.; Razumov, V. F.

    2016-12-01

    Key recent results obtained in studies of a new class of luminophores, colloidal quantum dots, are analyzed. Modern methods for the synthesis and post-synthetic treatment of colloidal quantum dots that make it possible to achieve record high quantum yield of luminescence and to modify their characteristics for specific applications are considered. Currently important avenues of research on colloidal quantum dots and the problems in and prospects for their practical applications in various fields are discussed. The bibliography includes 272 references.

  6. Catalytic Decoupling of Quantum Information

    DEFF Research Database (Denmark)

    Majenz, Christian; Berta, Mario; Dupuis, Frédéric

    2017-01-01

    of an uncorrelated ancilla system. This removes a restriction on the standard notion of decoupling, which becomes important for structureless resources, and yields a tight characterization in terms of the max-mutual information. Catalytic decoupling naturally unifies various tasks like the erasure of correlations......The decoupling technique is a fundamental tool in quantum information theory with applications ranging from quantum thermodynamics to quantum many body physics to the study of black hole radiation. In this work we introduce the notion of catalytic decoupling, that is, decoupling in the presence...... and quantum state merging, and leads to a resource theory of decoupling....

  7. Quantum Logic between Remote Quantum Registers

    CERN Document Server

    Yao, Norman Y; Laumann, Chris R; Bennett, Steven D; Duan, L -M; Lukin, Mikhail D; Jiang, Liang; Gorshkov, Alexey V

    2012-01-01

    We analyze two approaches to quantum state transfer in solid-state spin systems. First, we consider unpolarized spin-chains and extend previous analysis to various experimentally relevant imperfections, including quenched disorder, dynamical decoherence, and uncompensated long range coupling. In finite-length chains, the interplay between disorder-induced localization and decoherence yields a natural optimal channel fidelity, which we calculate. Long-range dipolar couplings induce a finite intrinsic lifetime for the mediating eigenmode; extensive numerical simulations of dipolar chains of lengths up to L=12 show remarkably high fidelity despite these decay processes. We further consider the extension of the protocol to bosonic systems of coupled oscillators. Second, we introduce a quantum mirror based architecture for universal quantum computing which exploits all of the spins in the system as potential qubits. While this dramatically increases the number of qubits available, the composite operations required...

  8. A Generalized Yield Criterion

    Institute of Scientific and Technical Information of China (English)

    Shijian YUAN; Dazhi XIAO; Zhubin HE

    2004-01-01

    A generalized yield criterion is proposed based on the metal plastic deformation mechanics and the fundamental formula in theory of plasticity. Using the generalized yield criterion, the reason is explained that Mises yield criterion and Tresca yield criterion do not completely match with experimental data. It has been shown that the yield criteria of ductile metals depend not only on the quadratic invariant of the deviatoric stress tensor J2, but also on the cubic invariant of the deviatoric stress tensor J3 and the ratio of the yield stress in pure shear to the yield stress in uniaxial tension k/σs. The reason that Mises yield criterion and Tresca yield criterion are not in good agreement with the experimental data is that the effect of J3 and k/σs is neglected.

  9. SOWING DENSITIES AND NPK AND LIMING LEVELS ON COMMON BEAN YIELD, IN CONVENTIONAL CROPPING SYSTEM, IN PONTA GROSSA, PARANÁ STATE, BRAZIL DENSIDADES DE SEMEADURA E NÍVEIS DE NPK E CALAGEM NA PRODUÇÃO DO FEIJOEIRO SOB PLANTIO CONVENCIONAL, EM PONTA GROSSA, PARANÁ

    Directory of Open Access Journals (Sweden)

    Armando de Albuquerque

    2008-03-01

    Full Text Available

    The objective of this study was to identify the most appropriate plant populations and fertilizer-liming levels for the conventional crop system, with the Iapar 81 cultivar, a type II common bean, on a heavy clay soil in Ponta Grossa, Paraná State, Brazil. An experiment was carried out in the 2003/2004 summer rainy growing season. The experimental design was a randomized block with four replications, and treatments in a 4 x 4 factorial scheme, with four populations (100 thousand, 200 thousand, 300 thousand, and 400 thousand plants ha-1 and four NPK-liming levels (0.0, 0.5, 1.0, and 1.5 times the recommended doses of NPK and lime. Plant height and grain yield, with their primary components (pod number per plant, grain number per pod and one hundred grains weight, were evaluated. Results allowed concluding that the increase of NPK-lime levels improved the plant height by 48%, the pod number per plant by 66%, and the grain yield by 88%, while the increase of plant population resulted in a decrease of 18% for plant height and 65% for pod number per plant, with no effect on the grain yield.

    KEY-WORDS: Phaseolus vulgaris; plant population; fertilization; soil liming.

    O presente estudo teve como objetivo identificar populações de plantas e níveis de adubação e calagem mais adequados para o plantio convencional da cultivar de

  10. Conventional cerebrospinal fluid scanning

    Energy Technology Data Exchange (ETDEWEB)

    Schicha, H.

    1985-06-01

    Conventional cerebrospinal fluid scanning (CSF scanning) today is mainly carried out in addition to computerized tomography to obtain information about liquor flow kinetics. Especially in patients with communicating obstructive hydrocephalus, CSF scanning is clinically useful for the decision for shunt surgery. In patients with intracranial cysts, CSF scanning can provide information about liquor circulation. Further indications for CSF scanning include the assessment of shunt patency especially in children, as well as the detection and localization of cerebrospinal fluid leaks.

  11. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  12. Quantum Blobs

    CERN Document Server

    de Gosson, Maurice A

    2011-01-01

    Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level sets defined by Fermi for the purpose of representing geometrically quantum states.

  13. Quantum Malware

    CERN Document Server

    Wu, L A; Wu, Lian-Ao; Lidar, Daniel

    2005-01-01

    Quantum computation and communication offer unprecedented advantages compared to classical information processing. Currently, quantum communication is moving from laboratory prototypes into real-life applications. When quantum communication networks become more widespread it is likely that they will be subject to attacks by hackers, virus makers, and other malicious intruders. Here we introduce the concept of "quantum malware" to describe such human-made intrusions. We offer a simple solution for storage of quantum information in a manner which protects quantum networks from quantum malware.

  14. The Linguistic Interpretation of Quantum Mechanics

    CERN Document Server

    Ishikawa, Shiro

    2012-01-01

    About twenty years ago, we proposed the mathematical formulation of Heisenberg's uncertainty principle, and further, we concluded that Heisenberg's uncertainty principle and EPR-paradox are not contradictory. This is true, however we now think that we should have argued about it under a certain firm interpretation of quantum mechanics. Recently we proposed the linguistic quantum interpretation (called quantum and classical measurement theory), which was characterized as a kind of metaphysical and linguistic turn of the Copenhagen interpretation. This turn from physics to language does not only extend quantum theory to classical systems but also yield the quantum mechanical world view (i.e., the philosophy of quantum mechanics, in other words, quantum philosophy). In fact, we can consider that traditional philosophies have progressed toward quantum philosophy. In this paper, we first review the linguistic quantum interpretation, and further, clarify the relation between EPR-paradox and Heisenberg's uncertainty...

  15. Quantum cloning

    OpenAIRE

    Scarani, Valerio; Iblisdir, Sofyan; Gisin, Nicolas; Acin, Antonio

    2005-01-01

    The impossibility of perfectly copying (or cloning) an arbitrary quantum state is one of the basic rules governing the physics of quantum systems. The processes that perform the optimal approximate cloning have been found in many cases. These "quantum cloning machines" are important tools for studying a wide variety of tasks, e.g. state estimation and eavesdropping on quantum cryptography. This paper provides a comprehensive review of quantum cloning machines (both for discrete-dimensional an...

  16. Solvothermal method to prepare graphene quantum dots by hydrogen peroxide

    Science.gov (United States)

    Tian, Renbing; Zhong, Suting; Wu, Juan; Jiang, Wei; Shen, Yewen; Jiang, Wei; Wang, Tianhe

    2016-10-01

    Graphene quantum dots (GQDs) have been synthesized by different chemical methods in recent years. For conventional chemical methods, it is inevitable to introduce a large amount of impurities in the preparation process. Long time of dialysis process increases the time cost extremely. Herein, we report a one-step solvothermal method for synthesizing GQDs with the application of hydrogen peroxide in N, N-Dimethylformamide (DMF) environment, which completely avoids the use of concentrated sulphuric acid and nitric acid to treat raw material and introduces no impurity in whole preparation process simultaneously for the first time. Pure GQDs can be obtained after evaporation/redissolution and filtration process with a strong blue emission at 15% quantum yield. This solvothermal method, not requiring dialysis process and complicated equipments, exhibits simple, eco-friendly and low time-cost properties. Besides high quantum yields, the as-prepared GQDs also show good photoluminescence stability in different pH conditions. The optical properties, morphology and structure of GQDs were studied by various equipments, implying potential application in biomedical fields and electronic device.

  17. 利用脉冲激光技术研究哺乳动物碳氧血红蛋白光解量子产率%Quantum yields in photolyses of mammalian carboxy-hemoglobin studied by pulsed laser pump-probe technique

    Institute of Scientific and Technical Information of China (English)

    赵瑾瑜; 渠敏; 李家璜; 张铮; 张淑仪; 水修基; 杨跃涛; 华子春

    2011-01-01

    本文利用脉冲光解法测量了哺乳动物碳氧血红蛋白的光解反应的量子产率.脉冲光解法是利用一束波长为532 nm、脉冲宽度为8 ns、重复频率为10 Hz的脉冲激光照射碳氧血红蛋白溶液,使其发生光解反应.考虑到碳氧血红蛋白溶液和其光解产物脱氧血红蛋白的光吸收系数不同,可利用另一束波长为432 nm的连续激光检测溶液在光解前、后的透射率的变化,以测定溶液的光解量子产率.利用此实验系统,对人、猪、牛、马和兔等5种哺乳动物的碳氧血红蛋白的光解量子产率进行了测量和研究,结果表明,不同物种的光解量子产率各不相同,其中猪、牛、马的碳氧血红蛋白的光解量子产率很接近,兔的碳氧血红蛋白的光解量子产率与其他物种的差异最大.最后,对测量的结果从血红蛋白的氨基酸序列、氢键和盐桥排布、四级结构等方面进行了分析与讨论.%Hemoglobin (Hb) as the allosteric protein, in photo-dissociations of liganded Hb has been studied widely. The mechanisms describing the cooperative binding of CO and other ligands to hemoglobins has been the subject of extensive studies as an important fundamental problem for a long time. In this paper, the quantum yields in photolyses of carboxy-hemoglobins (HbCO) of mammals, such as human,pig, bovine, horse and rabbit, are investigated by the optical pump-probe technique, in which the quantum yield is defined as the molecular number of photoproduct species divided by the absorbed photon number. In the optical pump-probe technique, the HbCO of the mammals are irradiated by a pulsed pumping laser beam with the wavelength 532 nm, pulse width 8 ns and the repetition frequency 10 Hz, then the HbCO is photo-dissociated.Meanwhile, another continuous optical beam with the wavelength 432 nm is used as a probe beam to detect the absorbance change induced by the photo-dissociation before and after the laser pulse illuminating

  18. Direct water-phase synthesis of lead sulfide quantum dots encapsulated by β-lactoglobulin for in vivo second near infrared window imaging with reduced toxicity.

    Science.gov (United States)

    Chen, Jun; Kong, Yifei; Wang, Wei; Fang, Hongwei; Wo, Yan; Zhou, Dejian; Wu, Ziying; Li, Yunxia; Chen, Shiyi

    2016-03-14

    Compared to conventional fluorescence imaging in the visible (400-700 nm) and NIR-I regions (700-900 nm), optical fluorescence imaging in the second near infrared window (NIR-II, 1000-1400 nm) offers reduced photon scattering, deeper tissue penetration and lower auto-fluorescence. Despite excellent imaging capabilities, current NIR-II probes have not yet reached their full potential due to weak quantum yield, low water solubility and suboptimal biocompatibility. To address these problems, we report herein a new NIR-II fluorescent PbS quantum dots (QDs) that are fabricated in water using β-lactoglobulin (LG) as a biological template. The LG-PbS QDs exhibit satisfactory dispersibility, relatively high quantum yield and favorable biocompatibility, and therefore are suitable for high-resolution in vivo imaging applications.

  19. Quantum CPU and Quantum Algorithm

    OpenAIRE

    Wang, An Min

    1999-01-01

    Making use of an universal quantum network -- QCPU proposed by me\\upcite{My1}, it is obtained that the whole quantum network which can implement some the known quantum algorithms including Deutsch algorithm, quantum Fourier transformation, Shor's algorithm and Grover's algorithm.

  20. Quantum Computer Games: Quantum Minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  1. Quantum Computer Games: Quantum Minesweeper

    Science.gov (United States)

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  2. Conventional and unconventional superconductivity

    Science.gov (United States)

    Fernandes, R. M.

    2012-02-01

    Superconductivity has been one of the most fruitful areas of research in condensed matter physics, bringing together researchers with distinct interests in a collaborative effort to understand from its microscopic basis to its potential for unprecedented technological applications. The concepts, techniques, and methods developed along its centennial history have gone beyond the realm of condensed matter physics and influenced the development of other fascinating areas, such as particle physics and atomic physics. These notes, based on a set of lectures given at the 2011 Advanced Summer School of Cinvestav, aim to motivate the young undergraduate student in getting involved in the exciting world of conventional and unconventional superconductors.

  3. Strategic interaction and conventions

    Directory of Open Access Journals (Sweden)

    Espinosa, María Paz

    2012-03-01

    Full Text Available The scope of the paper is to review the literature that employs coordination games to study social norms and conventions from the viewpoint of game theory and cognitive psychology. We claim that those two alternative approaches are in fact complementary, as they provide different insights to explain how people converge to a unique system of self-fulfilling expectations in presence of multiple, equally viable, conventions. While game theory explains the emergence of conventions relying on efficiency and risk considerations, the psychological view is more concerned with frame and labeling effects. The interaction between these alternative (and, sometimes, competing effects leads to the result that coordination failures may well occur and, even when coordination takes place, there is no guarantee that the convention eventually established will be the most efficient.

    El objetivo de este artículo es presentar la literatura que emplea los juegos de coordinación para el estudio de normas y convenciones sociales, que se han analizado tanto desde el punto de vista de la teoría de juegos como de la psicología cognitiva. Argumentamos en este trabajo que estos dos enfoques alternativos son en realidad complementarios, dado que ambos contribuyen al entendimiento de los procesos mediante los cuales las personas llegan a coordinarse en un único sistema de expectativas autorrealizadas, en presencia de múltiples convenciones todas ellas igualmente viables. Mientras que la teoría de juegos explica la aparición de convenciones basándose en argumentos de eficiencia y comportamientos frente al riesgo, el enfoque de la psicología cognitiva utiliza en mayor medida consideraciones referidas al entorno y naturaleza de las decisiones. La interacción entre estos efectos diferentes (y en ocasiones, rivales desemboca con frecuencia en fallos de coordinación y, aun cuando la coordinación se produce, no hay garantía de que la convención en vigor sea la m

  4. Quantum memristors

    Science.gov (United States)

    Pfeiffer, P.; Egusquiza, I. L.; di Ventra, M.; Sanz, M.; Solano, E.

    2016-07-01

    Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.

  5. Yield stress fluids slowly yield to analysis

    NARCIS (Netherlands)

    Bonn, D.; Denn, M.M.

    2009-01-01

    We are surrounded in everyday life by yield stress fluids: materials that behave as solids under small stresses but flow like liquids beyond a critical stress. For example, paint must flow under the brush, but remain fixed in a vertical film despite the force of gravity. Food products (such as mayon

  6. Quantum interpolation for high-resolution sensing.

    Science.gov (United States)

    Ajoy, Ashok; Liu, Yi-Xiang; Saha, Kasturi; Marseglia, Luca; Jaskula, Jean-Christophe; Bissbort, Ulf; Cappellaro, Paola

    2017-02-28

    Recent advances in engineering and control of nanoscale quantum sensors have opened new paradigms in precision metrology. Unfortunately, hardware restrictions often limit the sensor performance. In nanoscale magnetic resonance probes, for instance, finite sampling times greatly limit the achievable sensitivity and spectral resolution. Here we introduce a technique for coherent quantum interpolation that can overcome these problems. Using a quantum sensor associated with the nitrogen vacancy center in diamond, we experimentally demonstrate that quantum interpolation can achieve spectroscopy of classical magnetic fields and individual quantum spins with orders of magnitude finer frequency resolution than conventionally possible. Not only is quantum interpolation an enabling technique to extract structural and chemical information from single biomolecules, but it can be directly applied to other quantum systems for superresolution quantum spectroscopy.

  7. Quantum trajectories

    CERN Document Server

    Chattaraj, Pratim Kumar

    2010-01-01

    The application of quantum mechanics to many-particle systems has been an active area of research in recent years as researchers have looked for ways to tackle difficult problems in this area. The quantum trajectory method provides an efficient computational technique for solving both stationary and time-evolving states, encompassing a large area of quantum mechanics. Quantum Trajectories brings the expertise of an international panel of experts who focus on the epistemological significance of quantum mechanics through the quantum theory of motion.Emphasizing a classical interpretation of quan

  8. Self-assembled quantum dots in a nanowire system for quantum photonics

    OpenAIRE

    Heiss, M.; Fontana, Y.; Gustafsson, A; Wüst, G.; Magen, C.; O’Regan, D. D.; Luo, J. W.; Ketterer, B.; Conesa-Boj, S.; Kuhlmann, A. V.; Houel, J.; Russo-Averchi, E.; Morante, J. R.; Cantoni, M.; Marzari, N.

    2013-01-01

    Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-innanowire...

  9. A Quantum Focussing Conjecture

    CERN Document Server

    Bousso, Raphael; Leichenauer, Stefan; Wall, and Aron C

    2015-01-01

    We propose a universal inequality that unifies the Bousso bound with the classical focussing theorem. Given a surface $\\sigma$ that need not lie on a horizon, we define a finite generalized entropy $S_\\text{gen}$ as the area of $\\sigma$ in Planck units, plus the von Neumann entropy of its exterior. Given a null congruence $N$ orthogonal to $\\sigma$, the rate of change of $S_\\text{gen}$ per unit area defines a quantum expansion. We conjecture that the quantum expansion cannot increase along $N$. This extends the notion of universal focussing to cases where quantum matter may violate the null energy condition. Integrating the conjecture yields a precise version of the Strominger-Thompson Quantum Bousso Bound. Applied to locally parallel light-rays, the conjecture implies a Quantum Null Energy Condition: a lower bound on the stress tensor in terms of the second derivative of the von Neumann entropy. We sketch a proof of this novel relation in quantum field theory.

  10. Nitride quantum light sources

    Science.gov (United States)

    Zhu, T.; Oliver, R. A.

    2016-02-01

    Prototype nitride quantum light sources, particularly single-photon emitters, have been successfully demonstrated, despite the challenges inherent in this complex materials system. The large band offsets available between different nitride alloys have allowed device operation at easily accessible temperatures. A wide range of approaches has been explored: not only self-assembled quantum dot growth but also lithographic methods for site-controlled nanostructure formation. All these approaches face common challenges, particularly strong background signals which contaminate the single-photon stream and excessive spectral diffusion of the quantum dot emission wavelength. If these challenges can be successfully overcome, then ongoing rapid progress in the conventional III-V semiconductors provides a roadmap for future progress in the nitrides.

  11. Programmable Multimode Quantum Networks

    CERN Document Server

    Armstrong, Seiji; Janousek, Jiri; Hage, Boris; Treps, Nicolas; Lam, Ping Koy; Bachor, Hans-A

    2012-01-01

    Entanglement between large numbers of quantum modes is the quintessential resource for quantum information processing and future applications such as the quantum internet. Conventionally the generation of multimode entanglement in optics requires complex layouts of beam-splitters and phase shifters in order to transform the input modes in to entangled modes. These networks need substantial modification for every new set of entangled modes to be generated. Further, the complexity grows rapidly with the number of entangled modes as the number of detectors, phase locks and optical components needs to be increased. Here we report on the highly efficient and versatile generation of various multimode entangled states within one optical beam. By defining our modes to be combinations of different spatial regions of the beam, we may use just one pair of multi-pixel detectors and one local oscillator to measure an orthogonal set of modes. The transformation of this set into a desired set of entangled modes is calculate...

  12. New quantum mechanical model

    Institute of Scientific and Technical Information of China (English)

    吴宁; 阮图南

    1996-01-01

    A quantum mechanical model with one bosonic degree of freedom is discussed in detail. Conventionally, when a quantum mechanical model is constructed, one must know the corresponding classical model. And by applying the correspondence between the classical Poisson brackets and the canonical commutator, the canonical quantization condition can be obtained. In the quantum model, study of the corresponding classical model is needed first. In this model, the Lagrangian is an operator gauge invariant. After localization, in order to keep gauge invariance, the operator gauge potential must be introduced. The Eular-Lagrange equation of motion of the dynamical argument gives the usual operator equation of motion. And the operator gauge potential just gjves a constraint. This constraint is just the usual canonical quantization condition.

  13. Catalytic quantum error correction

    CERN Document Server

    Brun, T; Hsieh, M H; Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

    2006-01-01

    We develop the theory of entanglement-assisted quantum error correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to pre-shared entanglement. Conventional stabilizer codes are equivalent to dual-containing symplectic codes. In contrast, EAQEC codes do not require the dual-containing condition, which greatly simplifies their construction. We show how any quaternary classical code can be made into a EAQEC code. In particular, efficient modern codes, like LDPC codes, which attain the Shannon capacity, can be made into EAQEC codes attaining the hashing bound. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes which maintain a region of inherited noiseless qubits. We also give an alternative construction of EAQEC codes by making classical entanglement assisted codes coherent.

  14. Biodiesel from conventional feedstocks.

    Science.gov (United States)

    Du, Wei; Liu, De-Hua

    2012-01-01

    At present, traditional fossil fuels are used predominantly in China, presenting the country with challenges that include sustainable energy supply, energy efficiency improvement, and reduction of greenhouse gas emissions. In 2007, China issued The Strategic Plan of the Mid-and-Long Term Development of Renewable Energy, which aims to increase the share of clean energy in the country's energy consumption to 15% by 2020 from only 7.5% in 2005. Biodiesel, an important renewable fuel with significant advantages over fossil diesel, has attracted great attention in the USA and European countries. However, biodiesel is still in its infancy in China, although its future is promising. This chapter reviews biodiesel production from conventional feedstocks in the country, including feedstock supply and state of the art technologies for the transesterification reaction through which biodiesel is made, particularly the enzymatic catalytic process developed by Chinese scientists. Finally, the constraints and perspectives for China's biodiesel development are highlighted.

  15. Application of an InGaAsP diode laser to probe photodissociation dynamics - I(asterisk) quantum yields from n- and i-C3F7I and CH3I by laser gain vs absorption spectroscopy

    Science.gov (United States)

    Hess, W. P.; Kohler, S. J.; Haugen, H. K.; Leone, S. R.

    1986-01-01

    Initial measurements on I-asterisk yields of alkyl iodides at 266 nm are reported using gain vs. absorption spectroscopy with an InGaAsP diode probe laser. The results are 102 percent + or - 4 percent, 102 percent + or - 7 percent, and 73 percent + or - 4 percent for n-C3F7I, i-C3F7I, and CH3I respectively. Future prospects for the development of diode laser systems and for their use in dynamical studies are discussed.

  16. Particle physics: Quantum simulation of fundamental physics

    Science.gov (United States)

    Zohar, Erez

    2016-06-01

    Gauge theories underpin the standard model of particle physics, but are difficult to study using conventional computational methods. An experimental quantum system opens up fresh avenues of investigation. See Letter p.516

  17. Quantum Yields of Decomposition and Homo-Dimerization of Solid L-Alanine Induced by 7.2 eV Vacuum Ultraviolet Light Irradiation: An Estimate of the Half-Life of L-Alanine on the Surface of Space Objects

    Science.gov (United States)

    Izumi, Yudai; Nakagawa, Kazumichi

    2011-08-01

    One of the leading hypotheses regarding the origin of prebiotic molecules on primitive Earth is that they formed from inorganic molecules in extraterrestrial environments and were delivered by meteorites, space dust and comets. To evaluate the availability of extraterrestrial amino acids, it is necessary to examine their decomposition and oligomerization rates as induced by extraterrestrial energy sources, such as vacuum ultraviolet (VUV) and X-ray photons and high energy particles. This paper reports the quantum yields of decomposition ((8.2 ± 0.7) × 10-2 photon-1) and homo-dimerization ((1.2 ± 0.3) × 10-3 photon-1) and decomposition of the dimer (0.24 ± 0.06 photon-1) of solid l-alanine (Ala) induced by VUV light with an energy of 7.2 eV. Using these quantum yields, the half-life of l-Ala on the surface of a space object in the present earth orbit was estimated to be about 52 days, even when only photons with an energy of 7.2 eV emitted from the present Sun were considered. The actual half-life of solid l-Ala on the surface of a space object orbit around the present day Earth would certainly be much shorter than our estimate, because of the added effect of photons and particles of other energies. Thus, we propose that l-Ala needs to be shielded from solar VUV in protected environments, such as the interior of a meteorite, within a time scale of days after synthesis to ensure its arrival on the primitive Earth.

  18. The Decrease in Apparent Photosynthetic Quantum Yield in Wheat Leaves Caused by D, L-Glyceraldehyde Treatment%D,L-甘油醛处理引起的小麦叶片表观光合量子效率的降低

    Institute of Scientific and Technical Information of China (English)

    袁琳; 许大全

    2001-01-01

    Application of D, L-glyceraldehyde ( DL-GA, 10 mmol/L) , an inhibitor of phosphoribulokinase, decreased both net photosynthetic rate and apparent quantum yield of CO2 assimilation (Фc ) by about 20% -30% in winter wheat flag leaves. It also decreased the photochemical efficiency (△F/Fm′) of PS Ⅱ under actinic light, electron transport rate (ETR) and ATP content per unit leaf area but increased the intercellular CO2 concentration and nonphotochemical quenching of chlorophyll fluorescence (NPQ). These results indicate that after DLGA treatment the decline in apparent quantum yield in wheat flag leaves is due to the feedback inhibition of photo synthetic electron transport caused by restriction of carbon assimilation.%D,L-甘油醛(磷酸核酮糖激酶抑制剂,10mmol/L)处理小麦旗叶1 h可降低叶片净光合速率和表观量子效率.同时,光系统Ⅱ光化学效率(△F/Fm′)、电子传递速率(ETR)和单位叶面积ATP含量均降低,而胞间二氧化碳浓度(Ci)和叶绿素荧光非光化学猝灭(NPQ)增加.这些结果说明,D,L-甘油醛引起的小麦旗叶表观量子效率降低是由于光合碳同化受阻对光合电子传递的反馈抑制.

  19. Quantum Cosmology for Tunneling Universes

    CERN Document Server

    Kim, Sang Pyo

    2004-01-01

    In a quantum cosmological model consisting of a Euclidean region and a Lorentzian region, Hartle-Hawking's no-bounary wave function, and Linde's wave function and Vilenkin's tunneling wave function are briefly described and compared with each other. We put a particular emphasis on semiclassical gravity from quantum cosmology and compare it with the conventional quantum field theory in curved spacetimes. Finally, we discuss the recent debate on catastrophic particle production in the tunneling universe between Rubakov and Vilenkin within the semiclassical gravity.

  20. Quantum parallelism may be limited

    CERN Document Server

    Ozhigov, Yu I

    2016-01-01

    We consider quantum formalism limited by the classical simulating computer with the fixed memory. The memory is redistributed in the course of modeling by the variation of the set of classical states and the accuracy of the representation of amplitudes. This computational description completely preserves the conventional formalism and does not contradicts to experiments, but it makes impossible fast quantum algorithms. This description involves the slow down of quantum evolutions with the growth of the dimension of the minimal subspace containing entangled states, which arise in the evolution. This slow down is the single difference of the proposed formalism from the standard one; it is negligible for the systems from the usual experiments, including those in which many entangled particle participate, but grows rapidly in the attempt to realize the scalable quantum computations, which require the unlimited parallelism. The experimental verification of this version of quantum formalism is reduced to the fixati...

  1. What constitutes a convention? : implications for the coexistence of conventions

    OpenAIRE

    Kolstad, Ivar

    2002-01-01

    A model of repeated play of a coordination game, where stage games have a location in social space, and players receive noisy signals of the true location of their games, is reviewed. Sugden (1995) suggests that in such a model, there can be a stationary state of convention coexistence only if interaction is non-uniform across social space. This paper shows that an alternative definition of conventions, which links conventions to actions rather than expectations, permits convention coexistenc...

  2. Quantum robots and quantum computers

    Energy Technology Data Exchange (ETDEWEB)

    Benioff, P.

    1998-07-01

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  3. Quantum Darwinism

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H [Los Alamos National Laboratory

    2008-01-01

    Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.

  4. Quantum music

    CERN Document Server

    Putz, Volkmar

    2015-01-01

    We consider ways of conceptualizing, rendering and perceiving quantum music, and quantum art in general. Thereby we give particular emphasis to its non-classical aspects, such as coherent superposition and entanglement.

  5. Precision calculations for {gamma}{gamma} {yields} 4 fermions and H {yields} WW/ZZ {yields} 4 fermions

    Energy Technology Data Exchange (ETDEWEB)

    Bredenstein, A.

    2006-05-08

    In this work we provide precision calculations for the processes {gamma}{gamma} {yields} 4 fermions and H {yields} WW/ZZ {yields} 4 fermions. At a {gamma}{gamma} collider precise theoretical predictions are needed for the {gamma}{gamma} {yields} WW {yields} 4f processes because of their large cross section. These processes allow a measurement of the gauge-boson couplings {gamma}WW and {gamma}{gamma}WW. Furthermore, the reaction {gamma}{gamma} {yields} H {yields} WW/ZZ {yields} 4f arises through loops of virtual charged, massive particles. Thus, the coupling {gamma}{gamma}H can be measured and Higgs bosons with a relatively large mass could be produced. For masses M{sub H} >or(sim) 135 GeV the Higgs boson predominantly decays into W- or Z-boson pairs and subsequently into four leptons. The kinematical reconstruction of these decays is influenced by quantum corrections, especially real photon radiation. Since off-shell effects of the gauge bosons have to be taken into account below M{sub H} {approx} 2M{sub W/Z}, the inclusion of the decays of the gauge bosons is important. In addition, the spin and the CP properties of the Higgs boson can be determined by considering angular and energy distributions of the decay fermions. For a comparison of theoretical predictions with experimental data Monte Carlo generators are useful tools. We construct such programs for the processes {gamma}{gamma} {yields} WW {yields} 4f and H {yields} WW/ZZ {yields} 4f. On the one hand, they provide the complete predictions at lowest order of perturbation theory. On the other hand, they contain quantum corrections, which ca be classified into real corrections, connected with photons bremsstrahlung, and virtual corrections. Whereas the virtual quantum corrections to {gamma}{gamma} {yields} WW {yields} 4f are calculated in the double-pole approximation, i.e. only doubly-resonant contributions are taken into account, we calculate the complete O({alpha}) corrections for the H {yields} WW

  6. Observing Quantum Tunneling in Perturbation Series

    CERN Document Server

    Suzuki, H; Suzuki, Hiroshi; Yasuta, Hirofumi

    1997-01-01

    It is well-known that the quantum tunneling makes conventional perturbation series non-Borel summable. We use this fact reversely and attempt to extract the decay width of the false-vacuum from the actual perturbation series of the vacuum energy density (vacuum bubble diagrams). It is confirmed that, at least in quantum mechanical examples, our proposal provides a complimentary approach to the the conventional instanton calculus in the strong coupling region.

  7. Quantum Abacus

    CERN Document Server

    Cheon, T

    2004-01-01

    We show that the U(2) family of point interactions on a line can be utilized to provide the U(2) family of qubit operations for quantum information processing. Qubits are realized as localized states in either side of the point interaction which represents a controllable gate. The manipulation of qubits proceeds in a manner analogous to the operation of an abacus. Keywords: quantum computation, quantum contact interaction, quantum wire

  8. Quantum Econophysics

    OpenAIRE

    Esteban Guevara

    2006-01-01

    The relationships between game theory and quantum mechanics let us propose certain quantization relationships through which we could describe and understand not only quantum but also classical, evolutionary and the biological systems that were described before through the replicator dynamics. Quantum mechanics could be used to explain more correctly biological and economical processes and even it could encloses theories like games and evolutionary dynamics. This could make quantum mechanics a...

  9. Quantum cryptography

    NARCIS (Netherlands)

    Fehr, S.

    2010-01-01

    Quantum cryptography makes use of the quantum-mechanical behavior of nature for the design and analysis of cryptographic schemes. Optimally (but not always), quantum cryptography allows for the design of cryptographic schemes whose security is guaranteed solely by the laws of nature. This is in shar

  10. Probing the quantum-classical connection with open quantum dots

    Science.gov (United States)

    Ferry, D. K.; Akis, R.; Brunner, R.

    2015-10-01

    Open quantum dots provide a natural system in which to study both classical and quantum features of transport. From the classical point of view these dots possess a mixed phase space which yields families of closed, regular orbits as well as an expansive sea of chaos. As a closed test bed, they provide a natural system with a very rich set of eigen-states. When coupled to the environment through a pair of quantum point contacts, each of which passes several modes, the original quantum environment evolves into a set of decoherent and coherent states, which eventually couple to the classical states discussed above. The manner of this connection is governed strongly by decoherence theory. The remaining coherent states possess all the properties of pointer states. Here, we discuss the quantum-classical connection and how it appears within the experimental world.

  11. Probing quantum commutators

    CERN Document Server

    Rossi, Matteo A C; Paris, Matteo G A

    2016-01-01

    Quantum gravity theories predict a minimal length at the order of magnitude of the Planck length, under which the concepts of space and time lose every physical meaning. In quantum mechanics, the insurgence of such minimal length can be described by introducing a modified position-momentum commutator, which in turn yields a generalized uncertainty principle, where the uncertainty on the position measurement has a lower bound. The value of the minimal length is not predicted by theories and must be evaluated experimentally. In this paper, we address the quantum bound to estimability of the minimal uncertainty length by performing measurements on a harmonic oscillator, which is analytically solvable in the deformed algebra of the Hilbert subspace.

  12. Improving Ranking Using Quantum Probability

    OpenAIRE

    Melucci, Massimo

    2011-01-01

    The paper shows that ranking information units by quantum probability differs from ranking them by classical probability provided the same data used for parameter estimation. As probability of detection (also known as recall or power) and probability of false alarm (also known as fallout or size) measure the quality of ranking, we point out and show that ranking by quantum probability yields higher probability of detection than ranking by classical probability provided a given probability of ...

  13. Conventional mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Tobias Joseph

    2010-01-01

    Full Text Available The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU. Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.

  14. Algebraic formulation of quantum theory, particle identity and entanglement

    Science.gov (United States)

    Govindarajan, T. R.

    2016-08-01

    Quantum theory as formulated in conventional framework using statevectors in Hilbert spaces misses the statistical nature of the underlying quantum physics. Formulation using operators 𝒞∗ algebra and density matrices appropriately captures this feature in addition leading to the correct formulation of particle identity. In this framework, Hilbert space is an emergent concept. Problems related to anomalies and quantum epistemology are discussed.

  15. Euclidean and Lorentzian Quantum Gravity – Lessons from Two Dimensions

    NARCIS (Netherlands)

    Ambjørn, J.; Loll, R.; Nielsen, J. L.; Rolf, J.

    1998-01-01

    No theory of four-dimensional quantum gravity exists as yet. In this situation the two-dimensional theory, which can be analyzed by conventional field-theoretical methods, can serve as a toy model for studying some aspects of quantum gravity. It represents one of the rare settings in a quantum-gravi

  16. Quantum Computing for Quantum Chemistry

    Science.gov (United States)

    2010-09-01

    This three-year project consisted on the development and application of quantum computer algorithms for chemical applications. In particular, we developed algorithms for chemical reaction dynamics, electronic structure and protein folding. The first quantum computing for

  17. Quantum Operations as Quantum States

    CERN Document Server

    Arrighi, P; Arrighi, Pablo; Patricot, Christophe

    2004-01-01

    In this article we formalize the correspondence between quantum states and quantum operations, and harness its consequences. This correspondence was already implicit in Choi's proof of the operator sum representation of Completely Positive-preserving linear maps; we go further and show that all of the important theorems concerning quantum operations can be derived as simple corollaries of those concerning quantum states. As we do so the discussion first provides an elegant and original review of the main features of quantum operations. Next (in the second half of the paper) we search for more results to arise from the correspondence. Thus we propose a factorizability condition and an extremal trace-preservedness condition for quantum operations, give two novel Schmidt-type decompositions of bipartite pure states and two interesting composition laws for which the set of quantum operations and quantum states remain stable. The latter enables us to define a group structure upon the set of totally entangled state...

  18. Quantum memory in quantum cryptography

    CERN Document Server

    Mor, T

    1999-01-01

    [Shortened abstract:] This thesis investigates the importance of quantum memory in quantum cryptography, concentrating on quantum key distribution schemes. In the hands of an eavesdropper -- a quantum memory is a powerful tool, putting in question the security of quantum cryptography; Classical privacy amplification techniques, used to prove security against less powerful eavesdroppers, might not be effective when the eavesdropper can keep quantum states for a long time. In this work we suggest a possible direction for approaching this problem. We define strong attacks of this type, and show security against them, suggesting that quantum cryptography is secure. We start with a complete analysis regarding the information about a parity bit (since parity bits are used for privacy amplification). We use the results regarding the information on parity bits to prove security against very strong eavesdropping attacks, which uses quantum memories and all classical data (including error correction codes) to attack th...

  19. High yield DNA fragmentation using cyclical hydrodynamic shearing

    NARCIS (Netherlands)

    Shui, Lingling; Sparreboom, Wouter; Spang, Peter; Roeser, Tina; Nieto, Benjamin; Guasch, Francesc; Corbera, Antoni Homs; van den Berg, Albert; Carlen, Edwin

    2013-01-01

    We report a new DNA fragmentation technique that significantly simplifies conventional hydrodynamic shearing fragmentation by eliminating the need for sample recirculation while maintaining high fragmentation yield and low fragment length variation, and therefore, reduces instrument complexity and c

  20. High yield DNA fragmentation using cyclical hydrodynamic shearing

    NARCIS (Netherlands)

    Shui, Lingling; Sparreboom, Wouter; Spang, Peter; Roeser, Tina; Nieto, Benjamin; Guasch, Francesc; Corbera, Antoni Homs; van den Berg, Albert; Carlen, Edwin

    2013-01-01

    We report a new DNA fragmentation technique that significantly simplifies conventional hydrodynamic shearing fragmentation by eliminating the need for sample recirculation while maintaining high fragmentation yield and low fragment length variation, and therefore, reduces instrument complexity and

  1. ESD and the Rio Conventions

    Science.gov (United States)

    Sarabhai, Kartikeya V.; Ravindranath, Shailaja; Schwarz, Rixa; Vyas, Purvi

    2012-01-01

    Chapter 36 of Agenda 21, a key document of the 1992 Earth Summit, emphasised reorienting education towards sustainable development. While two of the Rio conventions, the Convention on Biological Diversity (CBD) and the United Nations Framework Convention on Climate Change (UNFCCC), developed communication, education and public awareness (CEPA)…

  2. Quantum Darwinism

    Science.gov (United States)

    Zurek, Wojciech Hubert

    2009-03-01

    Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system. It explains how the quantum fragility of a state of a single quantum system can lead to the classical robustness of states in their correlated multitude; shows how effective `wave-packet collapse' arises as a result of the proliferation throughout the environment of imprints of the state of the system; and provides a framework for the derivation of Born's rule, which relates the probabilities of detecting states to their amplitudes. Taken together, these three advances mark considerable progress towards settling the quantum measurement problem.

  3. Quantum entanglement and quantum operation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is a simple introduction to quantum entanglement and quantum operations. The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations. It includes remote state preparation by using any pure entangled states, nonlocal operation implementation using entangled states, entanglement capacity of two-qubit gates and two-qubit gates construction.

  4. Catalytic Decoupling of Quantum Information

    DEFF Research Database (Denmark)

    Majenz, Christian; Berta, Mario; Dupuis, Frédéric

    2017-01-01

    of an uncorrelated ancilla system. This removes a restriction on the standard notion of decoupling, which becomes important for structureless resources, and yields a tight characterization in terms of the max-mutual information. Catalytic decoupling naturally unifies various tasks like the erasure of correlations......The decoupling technique is a fundamental tool in quantum information theory with applications ranging from quantum thermodynamics to quantum many body physics to the study of black hole radiation. In this work we introduce the notion of catalytic decoupling, that is, decoupling in the presence...

  5. Quantum entanglement

    CERN Document Server

    Horodecki, R; Horodecki, M; Horodecki, K; Horodecki, Ryszard; Horodecki, Pawel; Horodecki, Michal; Horodecki, Karol

    2007-01-01

    All our former experience with application of quantum theory seems to say: {\\it what is predicted by quantum formalism must occur in laboratory}. But the essence of quantum formalism - entanglement, recognized by Einstein, Podolsky, Rosen and Schr\\"odinger - waited over 70 years to enter to laboratories as a new resource as real as energy. This holistic property of compound quantum systems, which involves nonclassical correlations between subsystems, is a potential for many quantum processes, including ``canonical'' ones: quantum cryptography, quantum teleportation and dense coding. However, it appeared that this new resource is very complex and difficult to detect. Being usually fragile to environment, it is robust against conceptual and mathematical tools, the task of which is to decipher its rich structure. This article reviews basic aspects of entanglement including its characterization, detection, distillation and quantifying. In particular, the authors discuss various manifestations of entanglement via ...

  6. Quantum relations

    CERN Document Server

    Weaver, Nik

    2010-01-01

    We define a "quantum relation" on a von Neumann algebra M \\subset B(H) to be a weak* closed operator bimodule over its commutant M'. Although this definition is framed in terms of a particular representation of M, it is effectively representation independent. Quantum relations on l^\\infty(X) exactly correspond to subsets of X^2, i.e., relations on X. There is also a good definition of a "measurable relation" on a measure space, to which quantum relations partially reduce in the general abelian case. By analogy with the classical setting, we can identify structures such as quantum equivalence relations, quantum partial orders, and quantum graphs, and we can generalize Arveson's fundamental work on weak* closed operator algebras containing a masa to these cases. We are also able to intrinsically characterize the quantum relations on M in terms of families of projections in M \\otimes B(l^2).

  7. Quantum technology and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Boshier, Malcolm [Los Alamos National Laboratory; Berkeland, Dana [USG; Govindan, Tr [ARO; Abo - Shaeer, Jamil [DARPA

    2010-12-10

    Quantum states of matter can be exploited as high performance sensors for measuring time, gravity, rotation, and electromagnetic fields, and quantum states of light provide powerful new tools for imaging and communication. Much attention is being paid to the ultimate limits of this quantum technology. For example, it has already been shown that exotic quantum states can be used to measure or image with higher precision or higher resolution or lower radiated power than any conventional technologies, and proof-of-principle experiments demonstrating measurement precision below the standard quantum limit (shot noise) are just starting to appear. However, quantum technologies have another powerful advantage beyond pure sensing performance that may turn out to be more important in practical applications: the potential for building devices with lower size/weight/power (SWaP) and cost requirements than existing instruments. The organizers of Quantum Technology Applications Workshop (QTAW) have several goals: (1) Bring together sponsors, researchers, engineers and end users to help build a stronger quantum technology community; (2) Identify how quantum systems might improve the performance of practical devices in the near- to mid-term; and (3) Identify applications for which more long term investment is necessary to realize improved performance for realistic applications. To realize these goals, the QTAW II workshop included fifty scientists, engineers, managers and sponsors from academia, national laboratories, government and the private-sector. The agenda included twelve presentations, a panel discussion, several breaks for informal exchanges, and a written survey of participants. Topics included photon sources, optics and detectors, squeezed light, matter waves, atomic clocks and atom magnetometry. Corresponding applications included communication, imaging, optical interferometry, navigation, gravimetry, geodesy, biomagnetism, and explosives detection. Participants

  8. Conventional colonoscopy; Konventionelle Kolonoskopie

    Energy Technology Data Exchange (ETDEWEB)

    Haefner, M. [Universitaetsklinik fuer Innere Medizin III, Klinische Abteilung fuer Gastroenterologie und Hepatologie, Wien (Austria)

    2008-02-15

    In the last 40 years colonoscopy has been the gold standard in diagnosis of conditions affecting the large intestine. We see its main disadvantages in the necessity for intestinal preparation and in the pain not infrequently experienced by patients who are not sedated. Widespread use of sedation has made it possible to improve patient acceptance in recent years. Complications of colonoscopy are rare, and even the removal of large polyps is regarded as a safe procedure. One of the main problems of colonoscopy is that a large number of far from trivial polyps - up to 20% in the literature - are overlooked. New developments, such as higher resolution videochips and chromoendoscopy, lead to a better diagnostic yield, especially of flat lesions. The rapidly developing sector of interventional colonoscopy in particular will ensure that colonoscopy continues to have an important place in the management of illnesses affecting the large intestine. (orig.) [German] Die Kolonoskopie war in den letzten 40 Jahren der Goldstandard zur Diagnostik von Dickdarmerkrankungen. Ihre Hauptnachteile liegen in der Notwendigkeit der Darmvorbereitung sowie nicht selten auftretenden Schmerzen beim nichtsedierten Patienten. Durch den breiten Einsatz der Sedierung konnte in den letzten Jahren die Patientenakzeptanz verbessert werden. Komplikationen der Kolonoskopie sind selten und selbst das Entfernen grosser Polypen wird als sicher angesehen. Eines der Hauptprobleme der Kolonoskopie liegt in der nicht unbetraechtlichen Anzahl uebersehener Polypen, die in der Literatur bis zu 20% betraegt. Neue Entwicklungen wie hoeher aufloesende Videochips oder die Chromoendoskopie fuehren zu einer verbesserten diagnostischen Ausbeute v. a. flacher Laesionen. Besonders das sich rasch entwickelnde Gebiet der interventionellen Kolonoskopie wird dafuer sorgen, dass die Kolonoskopie auch in Zukunft noch einen wichtigen Stellenwert beim Management von Dickdarmerkrankungen hat. (orig.)

  9. High-order Path Integral Monte Carlo methods for solving quantum dot problems

    CERN Document Server

    Chin, Siu A

    2014-01-01

    The conventional second-order Path Integral Monte Carlo method is plagued with the sign problem in solving many-fermion systems. This is due to the large number of anti-symmetric free fermion propagators that are needed to extract the ground state wave function at large imaginary time. In this work, we show that optimized fourth-order Path Integral Monte Carlo methods, which use no more than 5 free-fermion propagators, can yield accurate quantum dot energies for up to 20 polarized electrons with the use of the Hamiltonian energy estimator.

  10. Study on Grown Performance and High Yield Cultural Techniques of Conventional Rice Guinongzhan in Wenchang City%优质常规稻桂农占在文昌市的试种表现及高产栽培技术研究

    Institute of Scientific and Technical Information of China (English)

    郑丹艳

    2011-01-01

    Guinongzhan was the super rice breeding variety bred by rice research institute of Guangdong academy of agricultural sciences. It has characteristics of wide adaptability, high yield, great resistance and high quality, and is suitable to plant in Wenchang city as early and late rice. Agronomic traits, grain quality, resistance and yield performance were introduced and high yield cultural techniques of Guinongzhan were summarized including the time of sowing, breeding the vigorous seedlings, reasonable density, scientific fertilization, reasonable irrigation and pest control.%桂农占是广东省农业科学院水稻研究所选育的广适型优质超级稻品种。该品种具有适应性广、丰产性好、抗性强、米质优等特点,是一个适宜在海南省文昌市早、晚造种植的常规稻种。介绍了桂农占在文昌市的农艺性状、米质、抗性和产量表现,并总结了该品种的高产栽培技术,包括适时播种、培育壮秧、合理密植、科学施肥、合理排灌、及时防治病虫害等。

  11. Prospects for quantum computation with trapped ions

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; James, D.F.V.

    1997-12-31

    Over the past decade information theory has been generalized to allow binary data to be represented by two-state quantum mechanical systems. (A single two-level system has come to be known as a qubit in this context.) The additional freedom introduced into information physics with quantum systems has opened up a variety of capabilities that go well beyond those of conventional information. For example, quantum cryptography allows two parties to generate a secret key even in the presence of eavesdropping. But perhaps the most remarkable capabilities have been predicted in the field of quantum computation. Here, a brief survey of the requirements for quantum computational hardware, and an overview of the in trap quantum computation project at Los Alamos are presented. The physical limitations to quantum computation with trapped ions are discussed.

  12. Quantum Games and Quantum Discord

    CERN Document Server

    Nawaz, Ahmad

    2010-01-01

    We quantize prisoners dilemma and chicken game by our generalized quantization scheme to explore the role of quantum discord in quantum games. In order to establish this connection we use Werner-like state as an initial state of the game. In this quantization scheme measurement can be performed in entangled as well as in product basis. For the measurement in entangled basis the dilemma in both the games can be resolved by separable states with non-zero quantum discord. Similarly for product basis measurement the payoffs are quantum mechanical only for nonzero values of quantum discord.

  13. Modeling of dilute nitride cascaded quantum well solar cells for high efficiency photovoltaics

    Science.gov (United States)

    Vijaya, G.; Alemu, A.; Freundlich, A.

    2013-03-01

    III-V Dilute Nitride multi-quantum well structures are currently promising candidates to achieve 1 sun efficiencies of cell in a 4 junction configuration could yield 1 sun efficiencies greater than 40%. However for a conventional deep well design the characteristic carrier escape times could exceed that of radiative recombination hence limiting the current output of the cell, as has been indicated by prior experiments. In order to increase the current extraction here we evaluate the performance of a cascaded quantum well design whereby a thermally assisted resonant tunneling process is used to accelerate the carrier escape process (efficiency. The quantum efficiency of a p-i-n subcell where a periodic sequence of quantum wells with well and barrier thicknesses adjusted for the sequential extraction operation is calculated using a 2D drift diffusion model and taking into account absorption properties of resulting MQWs. The calculation also accounts for the E-field induced modifications of absorption properties and quantization in quantum wells. The results are then accounted for to calculate efficiencies for the proposed 4 junction design, and indicate potential for reaching efficiencies in excess of this structure is above 42% (1 sun) and above 50% (500 sun) AM1.5.

  14. YIELD OF AMARANTH

    African Journals Online (AJOL)

    department of Agricultural Engineering, University of Ibadan, Nigeria. (Received 28 ... properties, growth and shoot yield of large-green leafy amaranth (Amaranth sp.). Soil moisture ... microorganisms which stimulate the physical processes ... to plants and, consequently, crop establishment ... sustainable soil structure.

  15. 6 Grain Yield

    African Journals Online (AJOL)

    evaluate new interspecific genotypes for intensified double cropping of irrigated rice. The experimental ... the performance of the new irrigated .... nursing at a spacing of 20 cm between plants ..... if new technologies, comprising high yielding.

  16. Yield Mapping in Salix; Skoerdekartering av salix

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Christoffer; Gilbertsson, Mikael; Rogstrand, Gustav; Thylen, Lars

    2004-09-01

    The most common species for energy forest production is willow. Willow is able to produce a large amount of biomass in a short period of time. Growing willow has a potential to render a good financial result for the farmer if cultivated on fields with the right conditions and plenty of water. Under the right conditions growing willow can give the farmer a net income of 3,000 SEK (about 430 USD) per hectare and year, which is something that common cereal crops cannot compete with. However, this is not the common case since willow is often grown as a substitute crop on fields where cereal crop yield is low. The aim of this study was to reveal if it is possible to measure yield variability in willow, and if it is possible to describe the reasons for yield variation both within the field but also between different fields. Yield mapping has been used in conventional farming for about a decade. The principles for yield mapping are to continuously measure the yield while registering location by the use of GPS when harvesting the field. The collected data is then used to search for spatial variations within the field, and to try to understand the reasons for this variation. Since there is currently no commercial equipment for yield mapping in willow, a yield mapping system had to be developed within this project. The new system was installed on a Claas Jaguar harvester. The principle for yield mapping on the Claas Jaguar harvester is to measure the distance between the feeding rollers. This distance is correlated to the flow through the harvester. The speed and position of the machine was registered using GPS. Knowing the working width of the harvester this information was used to calculate the yield. All collected data was stored on a PDA computer. Soil samples were also collected from the yield mapped fields. This was to be able to test yield against both physical and chemical soil parameters. The result shows that it is possible to measure spatial variations of yield in

  17. Quantum process tomography of the quantum Fourier transform.

    Science.gov (United States)

    Weinstein, Yaakov S; Havel, Timothy F; Emerson, Joseph; Boulant, Nicolas; Saraceno, Marcos; Lloyd, Seth; Cory, David G

    2004-10-01

    The results of quantum process tomography on a three-qubit nuclear magnetic resonance quantum information processor are presented and shown to be consistent with a detailed model of the system-plus-apparatus used for the experiments. The quantum operation studied was the quantum Fourier transform, which is important in several quantum algorithms and poses a rigorous test for the precision of our recently developed strongly modulating control fields. The results were analyzed in an attempt to decompose the implementation errors into coherent (overall systematic), incoherent (microscopically deterministic), and decoherent (microscopically random) components. This analysis yielded a superoperator consisting of a unitary part that was strongly correlated with the theoretically expected unitary superoperator of the quantum Fourier transform, an overall attenuation consistent with decoherence, and a residual portion that was not completely positive-although complete positivity is required for any quantum operation. By comparison with the results of computer simulations, the lack of complete positivity was shown to be largely a consequence of the incoherent errors which occurred over the full quantum process tomography procedure. These simulations further showed that coherent, incoherent, and decoherent errors can often be identified by their distinctive effects on the spectrum of the overall superoperator. The gate fidelity of the experimentally determined superoperator was 0.64, while the correlation coefficient between experimentally determined superoperator and the simulated superoperator was 0.79; most of the discrepancies with the simulations could be explained by the cumulative effect of small errors in the single qubit gates.

  18. Comparison of conventional and non conventional methods of extraction of heartwood of Pterocarpus marsupium Roxb.

    Science.gov (United States)

    Devgun, Manish; Nanda, Arun; Ansari, Shahid H

    2012-01-01

    The renewed interest in plant-derived drugs has led to an increased need for efficient extraction methods. The present investigation was an attempt to evaluate and compare the conventional methods of extraction with non conventional methods of extraction, such as ultrasonic-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods. Pterocarpus marsupium Roxb. has been reported to contain bioactive phytochemicals, e.g., pterostilbene (3',5'-dimethoxy-4-stilbenol). The results showed that among the conventional extraction methods, percolation gave the highest yield. The non conventional methods were optimized. The extraction yield was the highest in case of MAE. The phytochemical screening of the extracts indicated similar groups of compounds in all the extracts. The thin layer chromatography showed the presence of pterostilbene in the extracts obtained by using percolation, MAE and UAE. In these extracts the quantification of pterostilbene was conducted by high performance liquid chromatography and the method was validated. The MAE method extracted significantly higher amount of pterostilbene.

  19. Conventional and nanotechniques for DNA methylation profiling.

    Science.gov (United States)

    Shanmuganathan, Rajasree; Basheer, Nazeema B; Amirthalingam, Laxmi; Muthukumar, Harshiny; Kaliaperumal, Rajendran; Shanmugam, Kumaran

    2013-01-01

    DNA methylation is critical for gene silencing and is associated with the incidence of many diseases, including cancer. Underlying molecular mechanisms of human diseases and tissue-specific gene expression have been elucidated based on DNA methylation studies. This review highlights the advantages and drawbacks of various methylation screening techniques: blotting, genomic sequencing, bisulfite sequencing, methylation-specific PCR, methylated DNA immunoprecipitation, microarray analysis, matrix-assisted laser desorption ionization time-of-flight mass spectroscopy, nanowire transistor detection procedure, quantum dot-based nanoassay, single-molecule real-time detection, fluorimetric assay, electrochemical detection, and atomic force spectroscopy. The review provides insight for selecting a method or a combination of methods for DNA methylation analysis. Convergence of conventional and contemporary nanotechniques to enumerate methylation at specific CpG sites of oncogene would fill the gap in diagnosis of cancer.

  20. Improved Quantum Genetic Algorithm in Application of Scheduling Engineering Personnel

    OpenAIRE

    Huaixiao Wang; Ling Li; Jianyong Liu; Yong Wang; Chengqun Fu

    2014-01-01

    To verify the availability of the improved quantum genetic algorithm in solving the scheduling engineering personnel problem, the following work has been carried out: the characteristics of the scheduling engineering personnel problem are analyzed, the quantum encoding method is proposed, and an improved quantum genetic algorithm is applied to address the issue. Taking the low efficiency and the bad performance of the conventional quantum genetic algorithm into account, a universal improved q...

  1. White Noise in Quantum Random Walk Search Algorithm

    Institute of Scientific and Technical Information of China (English)

    MA Lei; DU Jiang-Feng; LI Yun; LI Hui; KWEK L. C.; OH C. H.

    2006-01-01

    @@ The quantum random walk is a possible approach to construct new quantum search algorithms. It has been shown by Shenvi et al. [Phys. Rev. A 67 (2003)52307] that a kind of algorithm can perform an oracle search on a database of N items with O(√N) calling to the oracle, yielding a speedup similar to other quantum search algorithms.

  2. Quantum cryptography

    CERN Document Server

    Gilbert, Gerald; Hamrick, Michael

    2013-01-01

    This book provides a detailed account of the theory and practice of quantum cryptography. Suitable as the basis for a course in the subject at the graduate level, it crosses the disciplines of physics, mathematics, computer science and engineering. The theoretical and experimental aspects of the subject are derived from first principles, and attention is devoted to the practical development of realistic quantum communications systems. The book also includes a comprehensive analysis of practical quantum cryptography systems implemented in actual physical environments via either free-space or fiber-optic cable quantum channels. This book will be a valuable resource for graduate students, as well as professional scientists and engineers, who desire an introduction to the field that will enable them to undertake research in quantum cryptography. It will also be a useful reference for researchers who are already active in the field, and for academic faculty members who are teaching courses in quantum information s...

  3. Quantum Decoys

    CERN Document Server

    Arrighi, P

    2003-01-01

    Alice communicates with words drawn uniformly amongst $\\{\\ket{j}\\}_{j=1..n}$, the canonical orthonormal basis. Sometimes however Alice interleaves quantum decoys $\\{\\frac{\\ket{j}+i\\ket{k}}{\\sqrt{2}}\\}$ between her messages. Such pairwise superpositions of possible words cannot be distinguished from the message words. Thus as malevolent Eve observes the quantum channel, she runs the risk of damaging the superpositions (by causing a collapse). At the receiving end honest Bob, whom we assume is warned of the quantum decoys' distribution, checks upon their integrity with a measurement. The present work establishes, in the case of individual attacks, the tradeoff between Eve's information gain (her chances, if a message word was sent, of guessing which) and the disturbance she induces (Bob's chances, if a quantum decoy was sent, to detect tampering). Besides secure channel protocols, quantum decoys seem a powerful primitive for constructing n-dimensional quantum cryptographic applications. Moreover the methods emp...

  4. Quantum measurement

    CERN Document Server

    Busch, Paul; Pellonpää, Juha-Pekka; Ylinen, Kari

    2016-01-01

    This is a book about the Hilbert space formulation of quantum mechanics and its measurement theory. It contains a synopsis of what became of the Mathematical Foundations of Quantum Mechanics since von Neumann’s classic treatise with this title. Fundamental non-classical features of quantum mechanics—indeterminacy and incompatibility of observables, unavoidable measurement disturbance, entanglement, nonlocality—are explicated and analysed using the tools of operational quantum theory. The book is divided into four parts: 1. Mathematics provides a systematic exposition of the Hilbert space and operator theoretic tools and relevant measure and integration theory leading to the Naimark and Stinespring dilation theorems; 2. Elements develops the basic concepts of quantum mechanics and measurement theory with a focus on the notion of approximate joint measurability; 3. Realisations offers in-depth studies of the fundamental observables of quantum mechanics and some of their measurement implementations; and 4....

  5. Quantum Computers

    Science.gov (United States)

    2010-03-04

    efficient or less costly than their classical counterparts. A large-scale quantum computer is certainly an extremely ambi- tious goal, appearing to us...outperform the largest classical supercomputers in solving some specific problems important for data encryption. In the long term, another application...which the quantum computer depends, causing the quantum mechanically destructive process known as decoherence . Decoherence comes in several forms

  6. Quantum cryptography

    CERN Document Server

    Hughes, R J; Dyer, P L; Luther, G G; Morgan, G L; Schauer, M M; Hughes, Richard J; Dyer, P; Luther, G G; Morgan, G L; Schauer, M

    1995-01-01

    Quantum cryptography is a new method for secret communications offering the ultimate security assurance of the inviolability of a Law of Nature. In this paper we shall describe the theory of quantum cryptography, its potential relevance and the development of a prototype system at Los Alamos, which utilises the phenomenon of single-photon interference to perform quantum cryptography over an optical fiber communications link.

  7. An Overview of Quantum Teleportation for the Intelligence Community

    Energy Technology Data Exchange (ETDEWEB)

    Humble, Travis S [ORNL

    2007-01-01

    Quantum teleportation is a communication protocol for the exchange of information between remotely separated parties. We survey some prominent applications of quantum teleportation that show potential for collecting and analyzing intelligence. In addition to a background review of the underlying principles, we highlight the use of quantum teleportation in quantum key distribution, long-distance quantum communication networks, and quantum computing. The latter applications are significant for the Intelligence Community as they show promise for cracking conventional public-key encryption systems and providing alternate key distribution systems that are secure against attack.

  8. Improved Quantum Genetic Algorithm in Application of Scheduling Engineering Personnel

    Directory of Open Access Journals (Sweden)

    Huaixiao Wang

    2014-01-01

    Full Text Available To verify the availability of the improved quantum genetic algorithm in solving the scheduling engineering personnel problem, the following work has been carried out: the characteristics of the scheduling engineering personnel problem are analyzed, the quantum encoding method is proposed, and an improved quantum genetic algorithm is applied to address the issue. Taking the low efficiency and the bad performance of the conventional quantum genetic algorithm into account, a universal improved quantum genetic algorithm is introduced to solve the scheduling engineering personnel problem. Finally, the examples are applied to verify the effectiveness and superiority of the improved quantum genetic algorithm and the rationality of the encoding method.

  9. Quantum Dot-Photonic Crystal Cavity QED Based Quantum Information Processing

    Science.gov (United States)

    2012-08-14

    Physical Review A, 2012] 3. Study of the off-resonant quantum dot-cavity coupling in solid-state cavity QED system, and the phonon mediated off...resonant interaction between two quantum dots [Majumdar et al., Physical Review B , 2012] 4. Coherent optical spectroscopy of a single quantum dot via an off...Resonant cavity - much simpler than in conventional approaches [Majumdar et al, Physical Review B, 2011; Papageorge et al., New. Journal of Physics

  10. Quantum Dots-based Reverse Phase Protein Microarray

    Energy Technology Data Exchange (ETDEWEB)

    Shingyoji, Masato; Gerion, Daniele; Pinkel, Dan; Gray, Joe W.; Chen, Fanqing

    2005-07-15

    CdSe nanocrystals, also called quantum dots (Qdots) are a novel class of fluorophores, which have a diameter of a few nanometers and possess high quantum yield, tunable emission wavelength and photostability. They are an attractive alternative to conventional fluorescent dyes. Quantum dots can be silanized to be soluble in aqueous solution under biological conditions, and thus be used in bio-detection. In this study, we established a novel Qdot-based technology platform that can perform accurate and reproducible quantification of protein concentration in a crude cell lysate background. Protein lysates have been spiked with a target protein, and a dilution series of the cell lysate with a dynamic range of three orders of magnitude has been used for this proof-of-concept study. The dilution series has been spotted in microarray format, and protein detection has been achieved with a sensitivity that is at least comparable to standard commercial assays, which are based on horseradish peroxidase (HRP) catalyzed diaminobenzidine (DAB) chromogenesis. The data obtained through the Qdot method has shown a close linear correlation between relative fluorescence unit and relative protein concentration. The Qdot results are in almost complete agreement with data we obtained with the well-established HRP-DAB colorimetric array (R{sup 2} = 0.986). This suggests that Qdots can be used for protein quantification in microarray format, using the platform presented here.

  11. Quantum information

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, P

    1998-03-01

    There is more to information than a string of ones and zeroes the ability of ''quantum bits'' to be in two states at the same time could revolutionize information technology. In the mid-1930s two influential but seemingly unrelated papers were published. In 1935 Einstein, Podolsky and Rosen proposed the famous EPR paradox that has come to symbolize the mysteries of quantum mechanics. Two years later, Alan Turing introduced the universal Turing machine in an enigmatically titled paper, On computable numbers, and laid the foundations of the computer industry one of the biggest industries in the world today. Although quantum physics is essential to understand the operation of transistors and other solid-state devices in computers, computation itself has remained a resolutely classical process. Indeed it seems only natural that computation and quantum theory should be kept as far apart as possible surely the uncertainty associated with quantum theory is anathema to the reliability expected from computers? Wrong. In 1985 David Deutsch introduced the universal quantum computer and showed that quantum theory can actually allow computers to do more rather than less. The ability of particles to be in a superposition of more than one quantum state naturally introduces a form of parallelism that can, in principle, perform some traditional computing tasks faster than is possible with classical computers. Moreover, quantum computers are capable of other tasks that are not conceivable with their classical counterparts. Similar breakthroughs in cryptography and communication followed. (author)

  12. Quantum Networks for Generating Arbitrary Quantum States

    OpenAIRE

    Kaye, Phillip; Mosca, Michele

    2004-01-01

    Quantum protocols often require the generation of specific quantum states. We describe a quantum algorithm for generating any prescribed quantum state. For an important subclass of states, including pure symmetric states, this algorithm is efficient.

  13. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.;

    2015-01-01

    by recent advances in theory. As well as the well-understood overall picture, we also state clearly open questions for the field. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  14. Ecosystem Viable Yields

    CERN Document Server

    De Lara, Michel; Oliveros-Ramos, Ricardo; Tam, Jorge

    2011-01-01

    The World Summit on Sustainable Development (Johannesburg, 2002) encouraged the application of the ecosystem approach by 2010. However, at the same Summit, the signatory States undertook to restore and exploit their stocks at maximum sustainable yield (MSY), a concept and practice without ecosystemic dimension, since MSY is computed species by species, on the basis of a monospecific model. Acknowledging this gap, we propose a definition of "ecosystem viable yields" (EVY) as yields compatible i) with biological viability levels for all time and ii) with an ecosystem dynamics. To the difference of MSY, this notion is not based on equilibrium, but on viability theory, which offers advantages for robustness. For a generic class of multispecies models with harvesting, we provide explicit expressions for the EVY. We apply our approach to the anchovy--hake couple in the Peruvian upwelling ecosystem between the years 1971 and 1981.

  15. Reconsidering the conventional interpretation of the uncertainty relations

    CERN Document Server

    Dumitru, S

    2000-01-01

    The Conventional Interpretation of the Uncertainty Relations (CIUR) is reconsidered through a revaluation of its main assertions. It is shown that all the respective assertions are troubled by insurmountable defects. So it is revealed the indubitable failure of CIUR and the necessity of its abandonment as an unjustified doctrine which generates misconceptions and cofusions.Consequently theUR must be deprived of their quality of crucial formulae in distinction between quantum and classical physics. The theoretical UR are shown to be not indicators of measuring accuracies but simple fluctuations formmulae with natural analogous in classical (non-quantum) physics. That is why we propose that they to be named simply Heisenberg's relations. It is argued that the measurements description must be discriminated from quantum mechanics and done in a distict scientific branh disinct .

  16. Quantum physics without quantum philosophy

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Detlef [Muenchen Univ. (Germany). Mathematisches Inst.; Goldstein, Sheldon [Rutgers State Univ., Piscataway, NJ (United States). Dept. of Mathematics; Zanghi, Nino [Genova Univ. (Italy); Istituto Nazionale Fisica Nucleare, Genova (Italy)

    2013-02-01

    Integrates and comments on the authors' seminal papers in the field. Emphasizes the natural way in which quantum phenomena emerge from the Bohmian picture. Helps to answer many of the objections raised to Bohmian quantum mechanics. Useful overview and summary for newcomers and students. It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schroedinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  17. Probing intermediates of the induction period prior to nucleation and growth of semiconductor quantum dots

    Science.gov (United States)

    Liu, Mingyang; Wang, Kun; Wang, Linxi; Han, Shuo; Fan, Hongsong; Rowell, Nelson; Ripmeester, John A.; Renoud, Romain; Bian, Fenggang; Zeng, Jianrong; Yu, Kui

    2017-06-01

    Little is known about the induction period before the nucleation and growth of colloidal semiconductor quantum dots. Here, we introduce an approach that allows us to probe intermediates present in the induction period. We show that this induction period itself exhibits distinct stages with the evolution of the intermediates, first without and then with the formation of covalent bonds between metal cations and chalcogenide anions. The intermediates are optically invisible in toluene, while the covalent-bonded intermediates become visible as magic-size clusters when a primary amine is added. Such evolution of magic-size clusters provides indirect but compelling evidence for the presence of the intermediates in the induction period and supports the multi-step nucleation model. Our study reveals that magic-size clusters could be readily engineered in a single-size form, and suggests that the existence of the intermediates during the growth of conventional quantum dots results in low product yield.

  18. Quantum entanglement and quantum operation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It is a simple introduction to quantum entanglement and quantum operations.The authors focus on some applications of quantum entanglement and relations between two-qubit entangled states and unitary operations.It includes remote state preparation by using any pure entangled states,nonlocal operation implementation using entangled states,entanglement capacity of two-qubit gates and two-qubit gates construction.

  19. Quantum Physics Without Quantum Philosophy

    CERN Document Server

    Dürr, Detlef; Zanghì, Nino

    2013-01-01

    It has often been claimed that without drastic conceptual innovations a genuine explanation of quantum interference effects and quantum randomness is impossible. This book concerns Bohmian mechanics, a simple particle theory that is a counterexample to such claims. The gentle introduction and other contributions collected here show how the phenomena of non-relativistic quantum mechanics, from Heisenberg's uncertainty principle to non-commuting observables, emerge from the Bohmian motion of particles, the natural particle motion associated with Schrödinger's equation. This book will be of value to all students and researchers in physics with an interest in the meaning of quantum theory as well as to philosophers of science.

  20. Quantum spin liquids: a review

    Science.gov (United States)

    Savary, Lucile; Balents, Leon

    2017-01-01

    Quantum spin liquids may be considered ‘quantum disordered’ ground states of spin systems, in which zero-point fluctuations are so strong that they prevent conventional magnetic long-range order. More interestingly, quantum spin liquids are prototypical examples of ground states with massive many-body entanglement, which is of a degree sufficient to render these states distinct phases of matter. Their highly entangled nature imbues quantum spin liquids with unique physical aspects, such as non-local excitations, topological properties, and more. In this review, we discuss the nature of such phases and their properties based on paradigmatic models and general arguments, and introduce theoretical technology such as gauge theory and partons, which are conveniently used in the study of quantum spin liquids. An overview is given of the different types of quantum spin liquids and the models and theories used to describe them. We also provide a guide to the current status of experiments in relation to study quantum spin liquids, and to the diverse probes used therein.

  1. Quantum Algorithms

    Science.gov (United States)

    Abrams, D.; Williams, C.

    1999-01-01

    This thesis describes several new quantum algorithms. These include a polynomial time algorithm that uses a quantum fast Fourier transform to find eigenvalues and eigenvectors of a Hamiltonian operator, and that can be applied in cases for which all know classical algorithms require exponential time.

  2. Quantum Theory

    CERN Document Server

    Manning, Phillip

    2011-01-01

    The study of quantum theory allowed twentieth-century scientists to examine the world in a new way, one that was filled with uncertainties and probabilities. Further study also led to the development of lasers, the atomic bomb, and the computer. This exciting new book clearly explains quantum theory and its everyday uses in our world.

  3. Quantum Gravitodynamics

    CERN Document Server

    Sastry, R R

    1999-01-01

    The infinite dimensional generalization of the quantum mechanics of extended objects, namely, the quantum field theory of extended objects is employed to address the hitherto nonrenormalizable gravitational interaction following which the cosmological constant problem is addressed. The response of an electron to a weak gravitational field (linear approximation) is studied and the order $\\alpha$ correction to the magnetic gravitational moment is computed.

  4. Crop yields in intercropping

    NARCIS (Netherlands)

    Yu, Y.

    2016-01-01

    Abstract

    Intercropping, the cultivation of two or more crop species simultaneously in the same field, has been widely practiced by smallholder farmers in developing countries and is gaining increasing interest in developed countries. Intercropping can increase the yield per

  5. Crop yields in intercropping

    NARCIS (Netherlands)

    Yu, Y.

    2016-01-01

    Abstract

    Intercropping, the cultivation of two or more crop species simultaneously in the same field, has been widely practiced by smallholder farmers in developing countries and is gaining increasing interest in developed countries. Intercropping can increase the yield per

  6. Quantum entanglement

    CERN Document Server

    Hadjiivanov, Ludmil

    2015-01-01

    Expository paper providing a historical survey of the gradual transformation of the "philosophical discussions" between Bohr, Einstein and Schr\\"odinger on foundational issues in quantum mechanics into a quantitative prediction of a new quantum effect, its experimental verification and its proposed (and loudly advertised) applications. The basic idea of the 1935 paper of Einstein-Podolsky-Rosen (EPR) was reformulated by David Bohm for a finite dimensional spin system. This allowed John Bell to derive his inequalities that separate the prediction of quantum entanglement from its possible classical interpretation. We reproduce here their later (1971) version, reviewing on the way the generalization (and mathematical derivation) of Heisenberg's uncertainty relations (due to Weyl and Schr\\"odinger) needed for the passage from EPR to Bell. We also provide an improved derivation of the quantum theoretic violation of Bell's inequalities. Soon after the experimental confirmation of the quantum entanglement (culminati...

  7. Quantum magnetism

    CERN Document Server

    Richter, Johannes; Farnell, Damian; Bishop, Raymod

    2004-01-01

    The investigation of magnetic systems where quantum effects play a dominant role has become a very active branch of solid-state-physics research in its own right. The first three chapters of the "Quantum Magnetism" survey conceptual problems and provide insights into the classes of systems considered, namely one-dimensional, two-dimensional and molecular magnets. The following chapters introduce the methods used in the field of quantum magnetism, including spin wave analysis, exact diagonalization, quantum field theory, coupled cluster methods and the Bethe ansatz. The book closes with a chapter on quantum phase transitions and a contribution that puts the wealth of phenomena into the context of experimental solid-state physics. Closing a gap in the literature, this volume is intended both as an introductory text at postgraduate level and as a modern, comprehensive reference for researchers in the field.

  8. Quantum photonics

    CERN Document Server

    Pearsall, Thomas P

    2017-01-01

    This textbook employs a pedagogical approach that facilitates access to the fundamentals of Quantum Photonics. It contains an introductory description of the quantum properties of photons through the second quantization of the electromagnetic field, introducing stimulated and spontaneous emission of photons at the quantum level. Schrödinger’s equation is used to describe the behavior of electrons in a one-dimensional potential. Tunneling through a barrier is used to introduce the concept of non­locality of an electron at the quantum level, which is closely-related to quantum confinement tunneling, resonant tunneling, and the origin of energy bands in both periodic (crystalline) and aperiodic (non-crystalline) materials. Introducing the concepts of reciprocal space, Brillouin zones, and Bloch’s theorem, the determination of electronic band structure using the pseudopotential method is presented, allowing direct computation of the band structures of most group IV, group III-V, and group II-VI semiconducto...

  9. Quantum gravity

    CERN Document Server

    Kiefer, Claus

    2012-01-01

    The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantization of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of stri...

  10. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2016-01-01

    A Thorough Update of One of the Most Highly Regarded Textbooks on Quantum Mechanics Continuing to offer an exceptionally clear, up-to-date treatment of the subject, Quantum Mechanics, Sixth Edition explains the concepts of quantum mechanics for undergraduate students in physics and related disciplines and provides the foundation necessary for other specialized courses. This sixth edition builds on its highly praised predecessors to make the text even more accessible to a wider audience. It is now divided into five parts that separately cover broad topics suitable for any general course on quantum mechanics. New to the Sixth Edition * Three chapters that review prerequisite physics and mathematics, laying out the notation, formalism, and physical basis necessary for the rest of the book * Short descriptions of numerous applications relevant to the physics discussed, giving students a brief look at what quantum mechanics has made possible industrially and scientifically * Additional end-of-chapter problems with...

  11. Compact representations for the design of quantum logic

    CERN Document Server

    Niemann, Philipp

    2017-01-01

    This book discusses modern approaches and challenges of computer-aided design (CAD) of quantum circuits with a view to providing compact representations of quantum functionality. Focusing on the issue of quantum functionality, it presents Quantum Multiple-Valued Decision Diagrams (QMDDs – a means of compactly and efficiently representing and manipulating quantum logic. For future quantum computers, going well beyond the size of present-day prototypes, the manual design of quantum circuits that realize a given (quantum) functionality on these devices is no longer an option. In order to keep up with the technological advances, methods need to be provided which, similar to the design and synthesis of conventional circuits, automatically generate a circuit description of the desired functionality. To this end, an efficient representation of the desired quantum functionality is of the essence. While straightforward representations are restricted due to their (exponentially) large matrix descriptions and other de...

  12. Strategies and payoffs in quantum minority games

    CERN Document Server

    Sharif, Puya

    2011-01-01

    Game theory is the mathematical framework for analyzing strategic interactions in conflict and competition situations. In recent years quantum game theory has earned the attention of physicists, and has emerged as a branch of quantum information theory [1]. With the aid of entanglement and linear superposition of strategies, quantum games are shown to yield signifcant advantage over their classical counterparts. In this paper we explore optimal and equilibrium solutions to quantum minority games. Initial states with different level of entanglement are investigated. Focus will be on 4 and 6 player games with some N-player generalizations.

  13. Quantum Computation Toward Quantum Gravity

    Science.gov (United States)

    Zizzi, P. A.

    2001-08-01

    The aim of this paper is to enlighten the emerging relevance of Quantum Information Theory in the field of Quantum Gravity. As it was suggested by J. A. Wheeler, information theory must play a relevant role in understanding the foundations of Quantum Mechanics (the "It from bit" proposal). Here we suggest that quantum information must play a relevant role in Quantum Gravity (the "It from qubit" proposal). The conjecture is that Quantum Gravity, the theory which will reconcile Quantum Mechanics with General Relativity, can be formulated in terms of quantum bits of information (qubits) stored in space at the Planck scale. This conjecture is based on the following arguments: a) The holographic principle, b) The loop quantum gravity approach and spin networks, c) Quantum geometry and black hole entropy. From the above arguments, as they stand in the literature, it follows that the edges of spin networks pierce the black hole horizon and excite curvature degrees of freedom on the surface. These excitations are micro-states of Chern-Simons theory and account of the black hole entropy which turns out to be a quarter of the area of the horizon, (in units of Planck area), in accordance with the holographic principle. Moreover, the states which dominate the counting correspond to punctures of spin j = 1/2 and one can in fact visualize each micro-state as a bit of information. The obvious generalization of this result is to consider open spin networks with edges labeled by the spin -1/ 2 representation of SU(2) in a superposed state of spin "on" and spin "down." The micro-state corresponding to such a puncture will be a pixel of area which is "on" and "off" at the same time, and it will encode a qubit of information. This picture, when applied to quantum cosmology, describes an early inflationary universe which is a discrete version of the de Sitter universe.

  14. Low quantum defect laser performance

    Science.gov (United States)

    Bowman, Steven R.

    2017-01-01

    Low quantum defect lasers are possible using near-resonant optical pumping. This paper examines the laser material performance as the quantum defect of the laser is reduced. A steady-state model is developed, which incorporates the relevant physical processes in these materials and predicts extraction efficiency and waste heat generation. As the laser quantum defect is reduced below a few percent, the impact of fluorescence cooling must be included in the analysis. The special case of a net zero quantum defect laser is examined in detail. This condition, referred to as the radiation balance laser (RBL), is shown to provide two orders of magnitude lower heat generation at the cost of roughly 10% loss in extraction efficiency. Numerical examples are presented with the host materials Yb:YAG and Yb:Silica. The general conditions, which yield optimal laser efficiency, are derived and explored.

  15. Quantum teleportation with continuous measurements

    Science.gov (United States)

    Greplova, Eliska; Mølmer, Klaus; Andersen, Christian Kraglund

    2016-10-01

    We propose a scheme for quantum teleportation between two qubits, coupled sequentially to a cavity field. An implementation of the scheme is analyzed with superconducting qubits and a transmission line resonator, where measurements are restricted to continuous probing of the field leaking from the resonator rather than instantaneous projective Bell state measurement. We show that the past quantum state formalism S. Gammelmark, B. Julsgaard, and K. Mølmer, Phys. Rev. Lett. 111, 160401 (2013), 10.1103/PhysRevLett.111.160401 can be successfully applied to estimate what would have been the most likely Bell measurement outcome conditioned on our continuous signal record. This information determines which local operation on the target qubit yields the optimal teleportation fidelity. Our results emphasize the significance of applying a detailed analysis of quantum measurements in feedforward protocols in nonideal leaky quantum systems.

  16. Universal quantum back-action evasion

    CERN Document Server

    Tsang, Mankei

    2012-01-01

    Quantum mechanics is potentially advantageous for certain information-processing tasks, but its probabilistic nature and requirement of measurement back action often limit the precision of conventional classical information-processing devices, such as sensors and atomic clocks. Here we show that by engineering the dynamics of coupled quantum systems, it is possible to construct a subsystem that evades the measurement back action of quantum mechanics, at all times of interest, and obeys any classical dynamics, linear or nonlinear, that we choose. We call such a system a quantum-mechanics-free subsystem (QMFS). All of the observables of a QMFS are quantum-nondemolition (QND) observables; moreover, they are dynamical QND observables, thus demolishing the widely held belief that QND observables are constants of motion. QMFSs point to a new strategy for designing classical information-processing devices in regimes where quantum noise is detrimental. Potential applications include gravitational-wave detection, opto...

  17. Quantum cosmological metroland model

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Edward [DAMTP, Cambridge (United Kingdom); Franzen, Anne, E-mail: ea212@cam.ac.u, E-mail: a.t.franzen@uu.n [Spinoza Institute, Utrecht (Netherlands)

    2010-02-21

    Relational particle mechanics is useful for modelling whole-universe issues such as quantum cosmology or the problem of time in quantum gravity, including some aspects outside the reach of comparably complex mini-superspace models. In this paper, we consider the mechanics of pure shape and not scale of four particles on a line, so that the only physically significant quantities are ratios of relative separations between the constituents' physical objects. Many of our ideas and workings extend to the N-particle case. As such models' configurations resemble depictions of metro lines in public transport maps, we term them 'N-stop metrolands'. This 4-stop model's configuration space is a 2-sphere, from which our metroland mechanics interpretation is via the 'cubic' tessellation. This model yields conserved quantities which are mathematically SO(3) objects like angular momenta but are physically relative dilational momenta (i.e. coordinates dotted with momenta). We provide and interpret various exact and approximate classical and quantum solutions for 4-stop metroland; from these results one can construct expectations and spreads of shape operators that admit interpretations as relative sizes and the 'homogeneity of the model universe's contents', and also objects of significance for the problem of time in quantum gravity (e.g. in the naive Schroedinger and records theory timeless approaches).

  18. Quantum Physics and Reality

    CERN Document Server

    d'Espagnat, Bernard

    2011-01-01

    Contrary to classical physics, which was strongly objective i.e. could be interpreted as a description of mind-independent reality, standard quantum mechanics (SQM) is only weakly objective, that is to say, its statements, though intersubjectively valid, still merely refer to operations of the mind. Essentially, in fact, they are predictive of observations. On the view that SQM is universal conventional realism is thereby refuted. It is shown however that this does not rule out a broader form of realism, called here 'open realism', restoring the notion of mind-independent reality.

  19. Produção, qualidade dos frutos e estado nutricional da laranja valência sob fertirrigação e adubação convencional Yield, fruit quality and nutritional status of valencia orange under fertigation and conventional fertilization

    Directory of Open Access Journals (Sweden)

    Luiza H. Duenhas

    2005-04-01

    Full Text Available O objetivo deste trabalho foi comparar os efeitos de doses de nitrogênio, fósforo e potássio aplicadas via água de irrigação em comparação à aplicação convencional de fertilizantes, com irrigação e sem irrigação. O experimento foi conduzido em um pomar de laranja 'Valência' (Citrus sinensis Osbeck localizado em Pratânia - SP, durante três anos consecutivos, e analisados os dados do último ano de observação. As diferentes formas de aplicação dos fertilizantes e a redução das doses fornecidas via água de irrigação não resultaram em diferenças significativas sobre o número médio de frutos e produtividade. Também não foram constatadas diferenças estatísticas dos tratamentos sobre a qualidade do suco e o estado nutricional das plantas, com exceção do teor de fósforo.The purpose of this study was to compare doses of nitrogen, phosphorus and potassium applied through irrigation water and conventional fertilizer application, with and without irrigation. The experiment was carried out in a Valencia orange (Citrus sinensis Osbeck orchard in Pratania City, São Paulo State, Brazil, during three consecutive years. The data of the last year of observation were analysed. The different fertilizer application methods and the reduction of fertigation doses did not result in significative differences on the average number of fruits and productivily. Statistical differences of treatments on juice quality and plants nutritional status were not found, except leaf phosphorus.

  20. Theory of pulsed reaction yield detected magnetic resonance

    NARCIS (Netherlands)

    Nasibulov, E.A.; Kulik, L.V.; Kaptein, R.; Ivanov, K.L.

    2012-01-01

    We propose pulse sequences for Reaction Yield Detected Magnetic Resonance (RYDMR), which are based on refocusing the zero-quantum coherences in radical pairs by non-selective microwave pulses and using the population of a radical pair singlet spin state as an observable. The new experiments are

  1. CONVENTIONAL DEVELOPMENT OF ENVIRONMENTAL PREOCCUPATIONS

    OpenAIRE

    2011-01-01

    A great number of the conventions referring to nature, even if they do not refer ton particular species, were limited from the point of view of geography and territories: we may give as example here a convention for the protection of flora, fauna and panoramic beauties of America, the African convention for nature and natural resources… By the Stockholm conferences, from the 5th of June 1972, we entered in a “dynamic of globalization”. Article 1 of the Declaration that followed the conference...

  2. Conventional Armaments for coming decades .

    Directory of Open Access Journals (Sweden)

    S.K. Salwan

    1997-10-01

    Full Text Available Conventional arnaments have continued to play a decisive role even in the present scenario of nuclear weapons and electronic warfare. As a war-fighting technology, they are low cost, reliable, highly effective and proven in several battlefield situations. With the application of advancements in electronics, materials and manufacturing technologies, computers and propulsion technologies to conventional weapon systems, they are capable of having greater flexibility, lethality , accuracy and effectiveness. This communication gives an overview on advancements in conventional armament systems, emerging trends in weapon technologies and modern enabling technologies for advanced weapon systems.

  3. Comparison construction costs conventional rubblemound breakwaters/bermbreakwater

    NARCIS (Netherlands)

    Hauer, M.; Op den Velde, W.; Vrijling, J.K.; D' Angremond, K.

    1995-01-01

    Given a harbour location and a wave-climate, two different types of rubble-mound breakwaters were designed. Using realistic quarry yield curves and prices for production, transport and constmction, the total costs of the conventional statically stable and dynamically stable bermbreakwater designs we

  4. Quantum communications

    CERN Document Server

    Cariolaro, Gianfranco

    2015-01-01

    This book demonstrates that a quantum communication system using the coherent light of a laser can achieve performance orders of magnitude superior to classical optical communications Quantum Communications provides the Masters and PhD signals or communications student with a complete basics-to-applications course in using the principles of quantum mechanics to provide cutting-edge telecommunications. Assuming only knowledge of elementary probability, complex analysis and optics, the book guides its reader through the fundamentals of vector and Hilbert spaces and the necessary quantum-mechanical ideas, simply formulated in four postulates. A turn to practical matters begins with and is then developed by: ·         development of the concept of quantum decision, emphasizing the optimization of measurements to extract useful information from a quantum system; ·         general formulation of a transmitter–receiver system ·         particular treatment of the most popular quantum co...

  5. Estimating Corporate Yield Curves

    OpenAIRE

    Antionio Diaz; Frank Skinner

    2001-01-01

    This paper represents the first study of retail deposit spreads of UK financial institutions using stochastic interest rate modelling and the market comparable approach. By replicating quoted fixed deposit rates using the Black Derman and Toy (1990) stochastic interest rate model, we find that the spread between fixed and variable rates of interest can be modeled (and priced) using an interest rate swap analogy. We also find that we can estimate an individual bank deposit yield curve as a spr...

  6. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C Language

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  7. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  8. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  9. Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C Language

    OpenAIRE

    Blaha, Stephen

    2002-01-01

    We show a representation of Quantum Computers defines Quantum Turing Machines with associated Quantum Grammars. We then create examples of Quantum Grammars. Lastly we develop an algebraic approach to high level Quantum Languages using Quantum Assembly language and Quantum C language as examples.

  10. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  11. Quantum probability

    CERN Document Server

    Gudder, Stanley P

    2014-01-01

    Quantum probability is a subtle blend of quantum mechanics and classical probability theory. Its important ideas can be traced to the pioneering work of Richard Feynman in his path integral formalism.Only recently have the concept and ideas of quantum probability been presented in a rigorous axiomatic framework, and this book provides a coherent and comprehensive exposition of this approach. It gives a unified treatment of operational statistics, generalized measure theory and the path integral formalism that can only be found in scattered research articles.The first two chapters survey the ne

  12. Quantum mechanics

    CERN Document Server

    Powell, John L

    2015-01-01

    Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material.Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrödinger equation that includ

  13. Quantum Optics

    CERN Document Server

    Garrison, J C

    2008-01-01

    Quantum optics, i.e. the interaction of individual photons with matter, began with the discoveries of Planck and Einstein, but in recent years it has expanded beyond pure physics to become an important driving force for technological innovation. This book serves the broader readership growing out of this development by starting with an elementary description of the underlying physics and then building up a more advanced treatment. The reader is led from the quantum theory of thesimple harmonic oscillator to the application of entangled states to quantum information processing. An equally impor

  14. Quantum chemistry

    CERN Document Server

    Lowe, John P

    1993-01-01

    Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

  15. NULL Convention Floating Point Multiplier

    OpenAIRE

    Anitha Juliette Albert; Seshasayanan Ramachandran

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to p...

  16. Stimuli responsive polymer/quantum dot hybrid platforms modified at the nanoscale

    NARCIS (Netherlands)

    Tagit, Oya

    2010-01-01

    Quantum dots, QDs, receive growing attention from many research disciplines owing to their advantages as fluorescent probes including their nanoscale size (similar to biomolecules), high quantum yield and molar extinction coefficients, versatility in surface modification, broad excitation spectra (f

  17. Quantum algorithmic information theory

    OpenAIRE

    Svozil, Karl

    1995-01-01

    The agenda of quantum algorithmic information theory, ordered `top-down,' is the quantum halting amplitude, followed by the quantum algorithmic information content, which in turn requires the theory of quantum computation. The fundamental atoms processed by quantum computation are the quantum bits which are dealt with in quantum information theory. The theory of quantum computation will be based upon a model of universal quantum computer whose elementary unit is a two-port interferometer capa...

  18. Azadioxatriangulenium and Diazaoxatriangulenium: Quantum Yields and Fundamental Photophysical Properties

    DEFF Research Database (Denmark)

    Bogh, S. A.; Simmermacher, M.; Westberg, Michael

    2017-01-01

    Over the last decade, we have investigated and exploited the photophysical properties of triangulenium dyes. Azadioxatriangulenium (ADOTA) and diazaoxatriangulenium (DAOTA), in particular, have features that make them useful in various fluorescence-based technologies (e.g., bioimaging). Through o...

  19. Fluorescence quantum yield role on the Perovskite solar cell efficiency

    OpenAIRE

    Kramarenko, Mariia

    2016-01-01

    At the moment the use our society makes of the available energy sources is far from optimal. Only a small 5% fraction of the energy used for the electricity production comes from new renewable energy sources. For over several decades, in an attempt to maximize sunlight energy harvesting, researchers in thin film devices have been searching for the optimal materials. Out of the many thin film cell options available one of the most promising is the one based on perovskites. According to the NRE...

  20. Complementarity and Entanglement in Quantum Information Theory

    CERN Document Server

    Tessier, T E

    2004-01-01

    The restrictions that nature places on the distribution of correlations in a multipartite quantum system play fundamental roles in the evolution of such systems, and yield vital insights into the design of protocols for the quantum control of ensembles with potential applications in the field of quantum computing. We show how this entanglement sharing behavior may be studied in increasingly complex systems of both theoretical and experimental significance and demonstrate that entanglement sharing, as well as other unique features of entanglement, e.g. the fact that maximal information about a multipartite quantum system does not necessarily entail maximal information about its component subsystems, may be understood as specific consequences of the phenomenon of complementarity extended to composite quantum systems. We also present a local hidden-variable model supplemented by an efficient amount of classical communication that reproduces the quantum-mechanical predictions for the entire class of Gottesman-Kni...

  1. Conference on Mathematical Results in Quantum Mechanics

    CERN Document Server

    Exner, Pavel; Tater, Miloš; QMath-7

    1999-01-01

    At the age of almost three quarters of a century, quantum mechanics is by all accounts a mature theory. There were times when it seemed that it had borne its best fruit already and would give way to investigation of deeper levels of matter. Today this sounds like rash thinking. Modern experimental techniques have led to discoveries of numerous new quantum effects in solid state, optics and elsewhere. Quantum mechanics is thus gradually becoming a basis for many branches of applied physics, in this way entering our everyday life. While the dynamic laws of quantum mechanics are well known, a proper theoretical understanding requires methods which would allow us to de­ rive the abundance of observed quantum effects from the first principles. In many cases the rich structure hidden in the Schr6dinger equation can be revealed only using sophisticated tools. This constitutes a motivation to investigate rigorous methods which yield mathematically well-founded properties of quantum systems.

  2. High pressure intensification of cassava resistant starch (RS3) yields

    OpenAIRE

    2015-01-01

    Cassava starch, typically, has resistant starch type 3 (RS3) content of 2.4%. This paper shows that the RS3 yields can be substantially enhanced by debranching cassava starch using pullulanase followed by high pressure or cyclic high-pressure annealing. RS3 yield of 41.3% was obtained when annealing was carried out at 400 MPa/60°C for 15 min, whereas it took nearly 8 h to obtain the same yield under conventional atmospheric annealing at 60°C. The yield of RS3 could be further significantly in...

  3. Quantum fingerprinting

    CERN Document Server

    Buhrman, H; Watrous, J; De Wolf, R; Buhrman, Harry; Cleve, Richard; Watrous, John; Wolf, Ronald de

    2001-01-01

    Classical fingerprinting associates with each string a shorter string (its fingerprint), such that, with high probability, any two distinct strings can be distinguished by comparing their fingerprints alone. The fingerprints can be exponentially smaller than the original strings if the parties preparing the fingerprints share a random key, but not if they only have access to uncorrelated random sources. In this paper we show that fingerprints consisting of quantum information can be made exponentially smaller than the original strings without any correlations or entanglement between the parties: we give a scheme where the quantum fingerprints are exponentially shorter than the original strings and we give a test that distinguishes any two unknown quantum fingerprints with high probability. Our scheme implies an exponential quantum/classical gap for the equality problem in the simultaneous message passing model of communication complexity. We optimize several aspects of our scheme.

  4. Quantum computers.

    Science.gov (United States)

    Ladd, T D; Jelezko, F; Laflamme, R; Nakamura, Y; Monroe, C; O'Brien, J L

    2010-03-04

    Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future.

  5. Quantum Rotatability

    CERN Document Server

    Curran, Stephen

    2009-01-01

    In arXiv:0807.0677, K\\"ostler and Speicher observed that de Finetti's theorem on exchangeable sequences has a free analogue if one replaces exchangeability by the stronger condition of invariance under quantum permutations. In this paper we study sequences of noncommutative random variables whose joint distribution is invariant under quantum orthogonal transformations. We prove a free analogue of Freedman's characterization of conditionally independent Gaussian families, namely an infinite sequence of self-adjoint random variables is quantum orthogonally invariant if and only if they form an operator-valued free centered equivariant semicircular family. Similarly, we show that an infinite sequence of noncommutative random variables is quantum unitarily invariant if and only if they form an operator-valued free centered equivariant circular family. We provide an example to show that, as in the classical case, these results fail for finite sequences. We then give an approximation to how far the distribution of ...

  6. Quantum Brain?

    CERN Document Server

    Mershin, A; Skoulakis, E M C

    2000-01-01

    In order to create a novel model of memory and brain function, we focus our approach on the sub-molecular (electron), molecular (tubulin) and macromolecular (microtubule) components of the neural cytoskeleton. Due to their size and geometry, these systems may be approached using the principles of quantum physics. We identify quantum-physics derived mechanisms conceivably underlying the integrated yet differentiated aspects of memory encoding/recall as well as the molecular basis of the engram. We treat the tubulin molecule as the fundamental computation unit (qubit) in a quantum-computational network that consists of microtubules (MTs), networks of MTs and ultimately entire neurons and neural networks. We derive experimentally testable predictions of our quantum brain hypothesis and perform experiments on these.

  7. Estimating phase with a random generator: Strategies and resources in multiparameter quantum metrology

    Science.gov (United States)

    Yousefjani, Rozhin; Nichols, Rosanna; Salimi, Shahriar; Adesso, Gerardo

    2017-06-01

    Quantum metrology aims to exploit quantum phenomena to overcome classical limitations in the estimation of relevant parameters. We consider a probe undergoing a phase shift φ whose generator is randomly sampled according to a distribution with unknown concentration κ , which introduces a physical source of noise. We then investigate strategies for the joint estimation of the two parameters φ and κ given a finite number N of interactions with the phase imprinting channel. We consider both single qubit and multipartite entangled probes, and identify regions of the parameters where simultaneous estimation is advantageous, resulting in up to a twofold reduction in resources. Quantum enhanced precision is achievable at moderate N , while for sufficiently large N classical strategies take over and the precision follows the standard quantum limit. We show that full-scale entanglement is not needed to reach such an enhancement, as efficient strategies using significantly fewer qubits in a scheme interpolating between the conventional sequential and parallel metrological schemes yield the same effective performance. These results may have relevant applications in optimization of sensing technologies.

  8. Quantum lottery

    CERN Document Server

    CERN Bulletin

    2013-01-01

    On April Fools' Day, CERN Quantum Diaries blogger Pauline Gagnon held a giveaway of microscopic proportion. Up for grabs? Ten Higgs bosons, courtesy of CERN. Pauline announced the winners last week; let's see what they'll really be getting in the mail...   Custom-made Particle Zoo Higgs bosons were sent out to the winners. Read more about the prize in the Quantum Diaries post "Higgs boson lottery: when CERN plays April Fools' jokes".

  9. Quantum Physics

    OpenAIRE

    Haroche, Serge

    2013-01-01

    Mr Administrator,Dear colleagues,Ladies and gentlemen, “I think I can safely say that nobody understands quantum mechanics”. This statement, made by physicist Richard Feynman, expresses a paradoxical truth about the scientific theory that revolutionised our understanding of Nature and made an extraordinary contribution to our means of acting on and gaining information about the world. In this lecture, I will discuss quantum physics with you by attempting to resolve this paradox. And if I don’...

  10. Quantum optics

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund

    2013-01-01

    Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves.......Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves....

  11. Quantum optics

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund

    2013-01-01

    Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves.......Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves....

  12. Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction.

    Science.gov (United States)

    Müller, Knut; Krause, Florian F; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

    2014-12-15

    By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

  13. Quantum correlations and distinguishability of quantum states

    Science.gov (United States)

    Spehner, Dominique

    2014-07-01

    A survey of various concepts in quantum information is given, with a main emphasis on the distinguishability of quantum states and quantum correlations. Covered topics include generalized and least square measurements, state discrimination, quantum relative entropies, the Bures distance on the set of quantum states, the quantum Fisher information, the quantum Chernoff bound, bipartite entanglement, the quantum discord, and geometrical measures of quantum correlations. The article is intended both for physicists interested not only by collections of results but also by the mathematical methods justifying them, and for mathematicians looking for an up-to-date introductory course on these subjects, which are mainly developed in the physics literature.

  14. Delirium Quantum

    CERN Document Server

    Fuchs, Christopher A

    2009-01-01

    This pseudo-paper consists of excerpts drawn from two of my quantum-email samizdats. Section 1 draws a picture of a physical world whose essence is ``Darwinism all the way down.'' Section 2 outlines how quantum theory should be viewed in light of this, i.e., as being an expression of probabilism (in Bruno de Finetti or Richard Jeffrey's sense) all the way back up. Section 3 describes how the idea of ``identical'' quantum measurement outcomes, though sounding atomistic in character, nonetheless meshes well with a Jamesian style ``radical pluralism.'' Sections 4 and 5 further detail how quantum theory should not be viewed so much as a ``theory of the world,'' but rather as a theory of decision-making for agents immersed within a world of a particular character--the quantum world. Finally, Sections 6 and 7 attempt to sketch the very positive sense in which quantum theory is incomplete, but still just as complete is it can be. In total, I hope these heady speculations convey some of the excitement and potential I...

  15. Repeat-until-success quantum repeaters

    Science.gov (United States)

    Bruschi, David Edward; Barlow, Thomas M.; Razavi, Mohsen; Beige, Almut

    2014-09-01

    We propose a repeat-until-success protocol to improve the performance of probabilistic quantum repeaters. Conventionally, these rely on passive static linear-optics elements and photodetectors to perform Bell-state measurements (BSMs) with a maximum success rate of 50%. This is a strong impediment for entanglement swapping between distant quantum memories. Every time a BSM fails, entanglement needs to be redistributed between the corresponding memories in the repeater link. The key ingredients of our scheme are repeatable BSMs. Under ideal conditions, these turn probabilistic quantum repeaters into deterministic ones. Under realistic conditions, our protocol too might fail. However, using additional threshold detectors now allows us to improve the entanglement generation rate by almost orders of magnitude, at a nominal distance of 1000 km, compared to schemes that rely on conventional BSMs. This improvement is sufficient to make the performance of our scheme comparable to the expected performance of some deterministic quantum repeaters.

  16. Quantum Computation and Quantum Spin Dynamics

    NARCIS (Netherlands)

    Raedt, Hans De; Michielsen, Kristel; Hams, Anthony; Miyashita, Seiji; Saito, Keiji

    2001-01-01

    We analyze the stability of quantum computations on physically realizable quantum computers by simulating quantum spin models representing quantum computer hardware. Examples of logically identical implementations of the controlled-NOT operation are used to demonstrate that the results of a quantum

  17. Quantum Central Processing Unit and Quantum Algorithm

    Institute of Scientific and Technical Information of China (English)

    王安民

    2002-01-01

    Based on a scalable and universal quantum network, quantum central processing unit, proposed in our previous paper [Chin. Phys. Left. 18 (2001)166], the whole quantum network for the known quantum algorithms,including quantum Fourier transformation, Shor's algorithm and Grover's algorithm, is obtained in a unitied way.

  18. Quantum Computation and Quantum Spin Dynamics

    NARCIS (Netherlands)

    Raedt, Hans De; Michielsen, Kristel; Hams, Anthony; Miyashita, Seiji; Saito, Keiji

    2001-01-01

    We analyze the stability of quantum computations on physically realizable quantum computers by simulating quantum spin models representing quantum computer hardware. Examples of logically identical implementations of the controlled-NOT operation are used to demonstrate that the results of a quantum

  19. Comparing organic farming and land sparing: optimizing yield and butterfly populations at a landscape scale.

    Science.gov (United States)

    Hodgson, Jenny A; Kunin, William E; Thomas, Chris D; Benton, Tim G; Gabriel, Doreen

    2010-11-01

    Organic farming aims to be wildlife-friendly, but it may not benefit wildlife overall if much greater areas are needed to produce a given quantity of food. We measured the density and species richness of butterflies on organic farms, conventional farms and grassland nature reserves in 16 landscapes. Organic farms supported a higher density of butterflies than conventional farms, but a lower density than reserves. Using our data, we predict the optimal land-use strategy to maintain yield whilst maximizing butterfly abundance under different scenarios. Farming conventionally and sparing land as nature reserves is better for butterflies when the organic yield per hectare falls below 87% of conventional yield. However, if the spared land is simply extra field margins, organic farming is optimal whenever organic yields are over 35% of conventional yields. The optimal balance of land sparing and wildlife-friendly farming to maintain production and biodiversity will differ between landscapes.

  20. Quantum leptogenesis I

    Energy Technology Data Exchange (ETDEWEB)

    Anisimov, A. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Buchmueller, W. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Drewes, M. [Institute de Theorie des Phenomenes Physiques EPFL, Lausanne (Switzerland); Mendizabal, S. [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik

    2010-12-15

    Thermal leptogenesis explains the observed matter-antimatter asymmetry of the universe in terms of neutrino masses, consistent with neutrino oscillation experiments. We present a full quantum mechanical calculation of the generated lepton asymmetry based on Kadanoff-Baym equations. Origin of the asymmetry is the departure from equilibrium of the statistical propagator of the heavy Majorana neutrino, together with CP violating couplings. The lepton asymmetry is calculated directly in terms of Green's functions without referring to ''number densities''. Compared to Boltzmann and quantum Boltzmann equations, the crucial difference are memory effects, rapid oscillations much faster than the heavy neutrino equilibration time. These oscillations strongly suppress the generated lepton asymmetry, unless the standard model gauge interactions, which cause thermal damping, are properly taken into account. We find that these damping effects essentially compensate the enhancement due to quantum statistical factors, so that finally the conventional Boltzmann equations again provide rather accurate predictions for the lepton asymmetry. (orig.)

  1. Ion Trap Quantum Computers: Performance Limits and Experimental Progress

    Science.gov (United States)

    Hughes, Richard

    1998-03-01

    In a quantum computer information would be represented by the quantum mechanical states of suitable atomic-scale systems. (A single bit of information represented by a two-level quantum system is known as a qubit.) This notion leads to the possibility of computing with quantum mechanical superpositions of numbers ("quantum parallelism"), which for certain problems would make Quantum/quantum.html>quantum computation very much more efficient than classical computation. The possibility of rapidly factoring the large integers used in public-key cryptography is an important example. (Public key cryptosystems derive their security from the difficuty of factoring, and similar problems, with conventional computers.) Quantum computational hardware development is in its infancy, but an experimental study of quantum computation with laser-cooled trapped calcium ions that is under way at Los Alamos will be described. One of the pricipal obstacles to practical quantum computation is the inevitable loss of quantum coherence of the complex quantum states involved. The results of a theoretical analysis showing that quantum factoring of small integers should be possible with trapped ions will be presented. The prospects for larger-scale computations will be discussed.

  2. Dark Energy from Quantum Matter

    CERN Document Server

    Dappiaggi, Claudio; Möller, Jan; Pinamonti, Nicola

    2010-01-01

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the concordance model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations.

  3. Dark energy from quantum matter

    Energy Technology Data Exchange (ETDEWEB)

    Dappiaggi, Claudio; Hack, Thomas-Paul [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Moeller, Jan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Pinamonti, Nicola [Rome-2 Univ. (Italy). Dipt. di Matematica

    2010-07-15

    We study the backreaction of free quantum fields on a flat Robertson-Walker spacetime. Apart from renormalization freedom, the vacuum energy receives contributions from both the trace anomaly and the thermal nature of the quantum state. The former represents a dynamical realisation of dark energy, while the latter mimics an effective dark matter component. The semiclassical dynamics yield two classes of asymptotically stable solutions. The first reproduces the CDM model in a suitable regime. The second lacks a classical counterpart, but is in excellent agreement with recent observations. (orig.)

  4. NULL Convention Floating Point Multiplier

    Directory of Open Access Journals (Sweden)

    Anitha Juliette Albert

    2015-01-01

    Full Text Available Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  5. NULL convention floating point multiplier.

    Science.gov (United States)

    Albert, Anitha Juliette; Ramachandran, Seshasayanan

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  6. Towards a Theory of Convention

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg

    2006-01-01

    theory. Like for the study of common knowledge much has happened in this latter field since then. The theory of convention has been developed and extended so as to include multiple types as well as a basis for the study of social norms. However, classical game theory is currently undergoing severe crisis...... as a tool for understanding and explaining social phenomena; a crisis emerging from the problem of equilibrium selection around which any theory of convention must revolve. The so-called evolutionary turn in game theory marks a transition from the classical assumptions of rationality and common knowledge...... of such to evolutionary game theoretical frameworks inspired by the models of (Maynard Smith & Price 1973), (Taylor & Jonker 1978) and (Maynard Smith 1982). By providing an account of equilibrium selection these are thought to work as well-defined metaphors of learning processes upon which a revised theory of convention...

  7. The Global Approach to Quantum Field Theory

    Energy Technology Data Exchange (ETDEWEB)

    Fulling, S A [Texas A and M University (United States)

    2006-05-21

    Parts I and II develop the basic classical and quantum kinematics of fields and other dynamical systems. The presentation is conducted in the utmost generality, allowing for dynamical quantities that may be anticommuting (supernumbers) and theories subject to the most general possible gauge symmetry. The basic ingredients are action functionals and the Peierls bracket, a manifestly covariant replacement for the Poisson bracket and equal-time commutation relations. For DeWitt the logical progression is Peierls bracket {yields} Schwinger action principle {yields} Feynman functional integral although he points out that the historical development was in the opposite order. It must be pointed out that the Peierls-Schwinger-DeWitt approach, despite some advantages over initial-value formulations, has some troubles of its own. In particular, it has never completely escaped from the arena of scattering theory, the paradigm of conventional particle physics. One is naturally led to study matrix elements between an 'in-vacuum' and an 'out-vacuum' though such concepts are murky in situations, such as big bangs and black holes, where the ambient geometry is not asymptotically static in the far past and future. The newest material in the treatise appears in two chapters in part II devoted to the interpretation of quantum theory, incorporating some unpublished work of David Deutsch on the meaning of probability in physics. Parts III through V apply the formalism in depth to successively more difficult classes of systems: quantum mechanics, linear (free) fields, and interacting fields. DeWitt's characteristic tools of effective actions, heat kernels, and ghost fields are developed. Chapters 26 and 31 outline new approaches developed in collaboration with DeWitt's recent students C Molina-Paris and C Y Wang, respectively. The most of parts VI and VII consist of special topics, such as anomalies, particle creation by external fields, Unruh acceleration

  8. Rebuilding mathematics on a quantum logical foundation

    Science.gov (United States)

    DeJonghe, Richard J., III

    We construct a rich first-order quantum logic which generalizes the standard classical predicate logic used in the development of virtually all of modern mathematics, and we use this quantum logic to build the foundations of a new quantum mathematics. First, we prove both soundness and completeness for the quantum logic we develop, and also prove a powerful new completeness result which heretofore had been known to hold for classical, but not quantum, first-order logic. We then use our quantum logic to develop multiple areas of mathematics, including abstract algebra, axiomatic set theory, and arithmetic. In some preliminary investigations into quantum mathematics, Dunn found that the Peano axioms for arithmetic yield the same theorems using either classical or quantum logic. We prove a similar result for certain classes of abstract algebras, and then show that Dunn's result is not generic by presenting examples of quantum monoids, groups, lattices, vector spaces, and operator algebras, all which differ from their classical counterparts. Moreover, we find natural classes of quantum lattices, vector spaces, and operator algebras which all have a beautiful inter-relationship, and make some preliminary investigations into using these structures as a basis for a new mathematical formulation of quantum mechanics. We also develop a quantum set theory (equivalent to ZFC under classical logic) which is far more tractable than quantum set theory previously developed. We then use this set theory to construct a quantum version of the natural numbers, and develop an arithmetic of these numbers based upon an alternative to Peano's axioms (which avoids Dunn's theorem). Surprisingly, we find that these "quantum natural numbers" satisfy our arithmetical axioms if and only if the underlying truth values form a modular lattice, giving a new arithmetical characterization of this important lattice-theoretic property. Finally, we show that these numbers have a natural interpretation as

  9. Effect of different tillage intensity on yields and yield-forming factors in winter wheat

    Directory of Open Access Journals (Sweden)

    Martin Houšť

    2012-01-01

    Full Text Available The paper presents results of a study on application of minimum tillage technologies when growing winter wheat. Experiments were performed in the sugar-beet-growing region with loamy chernozem within the period of 2005–2009. Aanalysed and evaluated were effects of different methods of soil processing on yield-forming factors in stands of winter wheat grown after three different preceding crops (i.e. alfalfa, maize for silage and pea. Evaluated were the following four variants of tillage: (1 conventional ploughing to the depth of 0.22 m (Variant 1; (2 ploughing to the depth of 0.15 m (Variant 2; (3 direct sowing into the untilled soil (Variant 3, and (4 shallow tillage to the depth of 0.10 m (Variant 4.The effect of different tillage intensity on winter wheat yields was statistically non-significant after all forecrops. After alfalfa, the highest and the lowest average yields were recorded in Variant 2 (i.e. with ploughing to the depth of 0.15 m and Variant 3 (direct sowing into the untilled soil, respectively. After maize grown for silage, higher yields were obtained in Variant 2 and Variant 1 (conventional ploughing while in Variants 4 and 3 the obtained yields were lower. When growing winter wheat after pea as a preceding crop, the highest and the lowest average yields were recorded after direct sowing (Variant 3 and in Variant 1 (i.e. ploughing to the depth of 0.22 m, respectively. Results of studies on effect of different tillage technologies on yields of winter wheat crops indicate that under the given pedological and climatic conditions it is possible to apply methods of reduced tillage intensity. However, the choice of the corresponding technology must be performed with regard to the type of preceding crop.

  10. Quantum Physics for Beginners.

    Science.gov (United States)

    Strand, J.

    1981-01-01

    Suggests a new approach for teaching secondary school quantum physics. Reviews traditional approaches and presents some characteristics of the three-part "Quantum Physics for Beginners" project, including: quantum physics, quantum mechanics, and a short historical survey. (SK)

  11. Quantum Transmemetic Intelligence

    Science.gov (United States)

    Piotrowski, Edward W.; Sładkowski, Jan

    The following sections are included: * Introduction * A Quantum Model of Free Will * Quantum Acquisition of Knowledge * Thinking as a Quantum Algorithm * Counterfactual Measurement as a Model of Intuition * Quantum Modification of Freud's Model of Consciousness * Conclusion * Acknowledgements * References

  12. Quantum Physics for Beginners.

    Science.gov (United States)

    Strand, J.

    1981-01-01

    Suggests a new approach for teaching secondary school quantum physics. Reviews traditional approaches and presents some characteristics of the three-part "Quantum Physics for Beginners" project, including: quantum physics, quantum mechanics, and a short historical survey. (SK)

  13. Quantum Mechanics

    Science.gov (United States)

    Mandl, F.

    1992-07-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scientists R. J. Barlow and A. R. Barnett Quantum Mechanics aims to teach those parts of the subject which every physicist should know. The object is to display the inherent structure of quantum mechanics, concentrating on general principles and on methods of wide applicability without taking them to their full generality. This book will equip students to follow quantum-mechanical arguments in books and scientific papers, and to cope with simple cases. To bring the subject to life, the theory is applied to the all-important field of atomic physics. No prior knowledge of quantum mechanics is assumed. However, it would help most readers to have met some elementary wave mechanics before. Primarily written for students, it should also be of interest to experimental research workers who require a good grasp of quantum mechanics without the full formalism needed by the professional theorist. Quantum Mechanics features: A flow diagram allowing topics to be studied in different orders or omitted altogether. Optional "starred" and highlighted sections containing more advanced and specialized material for the more ambitious reader. Sets of problems at the end of each chapter to help student understanding. Hints and solutions to the problems are given at the end of the book.

  14. Towards a Theory of Convention

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg

    2006-01-01

    theory. Like for the study of common knowledge much has happened in this latter field since then. The theory of convention has been developed and extended so as to include multiple types as well as a basis for the study of social norms. However, classical game theory is currently undergoing severe crisis...... as a tool for understanding and explaining social phenomena; a crisis emerging from the problem of equilibrium selection around which any theory of convention must revolve. The so-called evolutionary turn in game theory marks a transition from the classical assumptions of rationality and common knowledge...

  15. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  16. Adiabatic quantum computation along quasienergies

    CERN Document Server

    Tanaka, Atushi

    2009-01-01

    The parametric deformations of quasienergies and eigenvectors of unitary operators are applied to the design of quantum adiabatic algorithms. The conventional, standard adiabatic quantum computation proceeds along eigenenergies of parameter-dependent Hamiltonians. By contrast, discrete adiabatic computation utilizes adiabatic passage along the quasienergies of parameter-dependent unitary operators. For example, such computation can be realized by a concatenation of parameterized quantum circuits, with an adiabatic though inevitably discrete change of the parameter. A design principle of adiabatic passage along quasienergy is recently proposed: Cheon's quasienergy and eigenspace anholonomies on unitary operators is available to realize anholonomic adiabatic algorithms [Tanaka and Miyamoto, Phys. Rev. Lett. 98, 160407 (2007)], which compose a nontrivial family of discrete adiabatic algorithms. It is straightforward to port a standard adiabatic algorithm to an anholonomic adiabatic one, except an introduction of...

  17. Quantum-Well Thermophotovoltaic Cells

    Science.gov (United States)

    Freudlich, Alex; Ignatiev, Alex

    2009-01-01

    Thermophotovoltaic cells containing multiple quantum wells have been invented as improved means of conversion of thermal to electrical energy. The semiconductor bandgaps of the quantum wells can be tailored to be narrower than those of prior thermophotovoltaic cells, thereby enabling the cells to convert energy from longer-wavelength photons that dominate the infrared-rich spectra of typical thermal sources with which these cells would be used. Moreover, in comparison with a conventional single-junction thermophotovoltaic cell, a cell containing multiple narrow-bandgap quantum wells according to the invention can convert energy from a wider range of wavelengths. Hence, the invention increases the achievable thermal-to-electrical energy-conversion efficiency. These thermophotovoltaic cells are expected to be especially useful for extracting electrical energy from combustion, waste-heat, and nuclear sources having temperatures in the approximate range from 1,000 to 1,500 C.

  18. Quantum Capacitance in Topological Insulators

    Science.gov (United States)

    Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V.; Zou, Jin; Wang, Kang L.

    2012-01-01

    Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature. PMID:22993694

  19. A Robust Quantum Random Number Generator Based on Bosonic Stimulation

    CERN Document Server

    H, Akshata Shenoy; Srikanth, R; Srinivas, T

    2011-01-01

    We propose a method to realize a robust quantum random number generator based on bosonic stimulation. A particular implementation that employs weak coherent pulses and conventional avalanche photo-diode detectors (APDs) is discussed.

  20. A variational eigenvalue solver on a photonic quantum processor.

    Science.gov (United States)

    Peruzzo, Alberto; McClean, Jarrod; Shadbolt, Peter; Yung, Man-Hong; Zhou, Xiao-Qi; Love, Peter J; Aspuru-Guzik, Alán; O'Brien, Jeremy L

    2014-07-23

    Quantum computers promise to efficiently solve important problems that are intractable on a conventional computer. For quantum systems, where the physical dimension grows exponentially, finding the eigenvalues of certain operators is one such intractable problem and remains a fundamental challenge. The quantum phase estimation algorithm efficiently finds the eigenvalue of a given eigenvector but requires fully coherent evolution. Here we present an alternative approach that greatly reduces the requirements for coherent evolution and combine this method with a new approach to state preparation based on ansätze and classical optimization. We implement the algorithm by combining a highly reconfigurable photonic quantum processor with a conventional computer. We experimentally demonstrate the feasibility of this approach with an example from quantum chemistry--calculating the ground-state molecular energy for He-H(+). The proposed approach drastically reduces the coherence time requirements, enhancing the potential of quantum resources available today and in the near future.

  1. Fermion-induced quantum critical points.

    Science.gov (United States)

    Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong

    2017-08-22

    A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.

  2. An Efficient Data Communication Using Conventional Codes

    Directory of Open Access Journals (Sweden)

    Mrs. Nikam Pratibha Madhavrao

    2014-07-01

    Full Text Available The BER performance of conventional FFT-OFDM system is compared with DWT-OFDM system and DCT-OFDM system in an AWGN environment and Saleh-Valenzuela (SV channel model at 60 GHz. Several wavelets such as Haar, Daubechies, Symlet, biorthogonal are considered. The BER is calculated for signaling format BPSK and the performance is analyzed at 60 GHz. Simulation results show that DCT based scheme yields the lowest average bit error rate. While out of all wavelet mother used Haar and Daubechies wavelet based scheme yields lower BER than FFT-OFDM for an AWGN channel. But it may include the implementation of forward error correction techniques such as convolution codes. An efficient channel estimation algorithm may be included for performance evaluation of DCT-OFDM and DWT- OFDM working at 60 GHz band. We introduce the Interfacing Techniques for Accessing data transfer data delivery. By using our approach we are increasing the efficiency of the data communication.

  3. Quantum asymmetric cryptography with symmetric keys

    Science.gov (United States)

    Gao, Fei; Wen, Qiaoyan; Qin, Sujuan; Zhu, Fuchen

    2009-12-01

    Based on quantum encryption, we present a new idea for quantum public-key cryptography (QPKC) and construct a whole theoretical framework of a QPKC system. We show that the quantum-mechanical nature renders it feasible and reasonable to use symmetric keys in such a scheme, which is quite different from that in conventional public-key cryptography. The security of our scheme is analyzed and some features are discussed. Furthermore, the state-estimation attack to a prior QPKC scheme is demonstrated.

  4. Quantum asymmetric cryptography with symmetric keys

    OpenAIRE

    Gao, Fei; Wen, Qiao-Yan; Qin, Su-Juan; Zhu, Fu-Chen

    2008-01-01

    Based on quantum encryption, we present a new idea for quantum public-key cryptography (QPKC) and construct a whole theoretical framework of a QPKC system. We show that the quantum-mechanical nature renders it feasible and reasonable to use symmetric keys in such a scheme, which is quite different from that in conventional public-key cryptography. The security of our scheme is analyzed and some features are discussed. Furthermore, the state-estimation attack to a prior QPKC scheme is demonstr...

  5. Quantum asymmetric cryptography with symmetric keys

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on quantum encryption,we present a new idea for quantum public-key cryptography (QPKC) and construct a whole theoretical framework of a QPKC system. We show that the quantum-mechanical nature renders it feasible and reasonable to use symmetric keys in such a scheme,which is quite different from that in conventional public-key cryptography. The security of our scheme is analyzed and some features are discussed. Furthermore,the state-estimation attack to a prior QPKC scheme is demonstrated.

  6. Quantum asymmetric cryptography with symmetric keys

    Institute of Scientific and Technical Information of China (English)

    GAO Fei; WEN QiaoYan; QIN SuJuan; ZHU FuChen

    2009-01-01

    Based on quantum encryption, we present a new idea for quantum public-key cryptography (QPKC) and construct a whole theoretical framework of a QPKC system. We show that the quantum-mechanical nature renders it feasible and reasonable to use symmetric keys in such a scheme, which is quite different from that in conventional public-key cryptography. The security of our scheme is analyzed and some features are discussed. Furthermore, the state-estimation attack to a prior QPKC scheme is demonstrated.

  7. Hybrid Models in Loop Quantum Cosmology

    CERN Document Server

    Navascués, B Elizaga; Marugán, G A Mena

    2016-01-01

    In the framework of Loop Quantum Cosmology, inhomogeneous models are usually quantized by means of a hybrid approach that combines loop quantization techniques with standard quantum field theory methods. This approach is based on a splitting of the phase space in a homogeneous sector, formed by global, zero-modes, and an inhomogeneous sector, formed by the remaining, infinite number of modes, that describe the local degrees of freedom. Then, the hybrid quantization is attained by adopting a loop representation for the homogeneous gravitational sector, while a Fock representation is used for the inhomogeneities. The zero-mode of the Hamiltonian constraint operator couples the homogeneous and inhomogeneous sectors. The hybrid approach, therefore, is expected to provide a suitable quantum theory in regimes where the main quantum effects of the geometry are those affecting the zero-modes, while the inhomogeneities, still being quantum, can be treated in a more conventional way. This hybrid strategy was first prop...

  8. Biocompatible quantum dots for biological applications.

    Science.gov (United States)

    Rosenthal, Sandra J; Chang, Jerry C; Kovtun, Oleg; McBride, James R; Tomlinson, Ian D

    2011-01-28

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots.

  9. Hydrogen storage: beyond conventional methods.

    Science.gov (United States)

    Dalebrook, Andrew F; Gan, Weijia; Grasemann, Martin; Moret, Séverine; Laurenczy, Gábor

    2013-10-09

    The efficient storage of hydrogen is one of three major hurdles towards a potential hydrogen economy. This report begins with conventional storage methods for hydrogen and broadly covers new technology, ranging from physical media involving solid adsorbents, to chemical materials including metal hydrides, ammonia borane and liquid precursors such as alcohols and formic acid.

  10. Grounding Damage to Conventional Vessels

    DEFF Research Database (Denmark)

    Lützen, Marie; Simonsen, Bo Cerup

    2003-01-01

    The present paper is concerned with rational design of conventional vessels with regard to bottom damage generated in grounding accidents. The aim of the work described here is to improve the design basis, primarily through analysis of new statistical data for grounding damage. The current...

  11. Inventory non-conventional gas

    Energy Technology Data Exchange (ETDEWEB)

    Muntendam-Bos, A.G.; Wassing, B.B.T.; Ter Heege, J.H.; Van Bergen, F.; Schavemaker, Y.A.; Van Gessel, S.F.; De Jong, M.L.; Nelskamp, S.; Van Thienen-Visser, K.; Guasti, E.; Van den Belt; Marges, V.C. [TNO Built Environment and Geosciences, Utrecht (Netherlands)

    2009-10-15

    This report describes the results of the inventory for each non-conventional gas resource expected to be present in the Netherlands, which are: Tight Gas, Shallow gas, Coal bed Methane (CBM), Shale gas, Basin Centered Gas, Aquifer Gas and Stratigraphic traps.

  12. Scaling-up of complex whole-cell bioconversions in conventional and non-conventional media.

    Science.gov (United States)

    Marques, Marco P C; de Carvalho, Carla C C R; Cabral, Joaquim M S; Fernandes, Pedro

    2010-07-01

    The use of whole cells is becoming a more common approach in pharmaceutical and agrochemical industries in order to obtain pure compounds with fewer production steps, higher yields, and cleaner processes, as compared to those achieved with traditional strategies. Whole cells are often used as enzymes pools, in particular when multi-step reactions and/or co-factor regeneration are envisaged. Nonetheless, published information on the scale-up of such systems both in aqueous and in two-phase aqueous-organic systems is relatively scarce. The present work aims to evaluate suitable scale-up criteria in conventional and non-conventional medium for a whole-cell bioconversion that uses resting cells of Mycobacterium sp. NRRL B-3805 to cleave the side chain of beta-sitosterol, a poorly water-soluble substrate. The experiments were performed in 24-well microtiter plates and in 250 mL shaken flasks as orbital stirred systems, and in 300 mL stirred tanks as mechanically stirred systems. Results show that productivity yields were similar in all scales tested, when maintaining oxygen mass transfer coefficients constant in aqueous systems, or when maintaining constant volumetric power consumption in aqueous-organic two-phase systems.

  13. Corrected Kondo temperature beyond the conventional Kondo scaling limit

    Science.gov (United States)

    Li, ZhenHua; Wei, JianHua; Zheng, Xiao; Yan, YiJing; Luo, Hong-Gang

    2017-05-01

    In the Kondo systems such as the magnetic impurity screened by the conduction electrons in a metal host, as well as the quantum dots connected by the leads, the low energy behaviors have universal dependence on the T/T\\text{K}0 or eV/{{k}\\text{B}}T\\text{K}0 , where T\\text{K}0 is the conventional Kondo temperature. However, it was shown that this scaling behavior is only valid at low-energy; this is called the Kondo scaling limit. Here we explore the extention of the scaling parameter range by introducing the corrected Kondo temperature T K, which may depend on the temperature and bias, as well as the other external parameters. We define the corrected Kondo temperature by scaling the local density of states near the Fermi level, obtained by accurate hierarchy of equations of motion approach at finite temperature and finite bias, and thus obtain a phenomenological expression of the corrected Kondo temperature. By using the corrected Kondo temperature as a characteristic energy scale, the conductance of the quantum dot can be well scaled in a wide parameter range, even two orders beyond the conventional scaling parameter range. Our work indicates that the Kondo scaling, although dominated by the conventional Kondo temperature in the low-energy of the Kondo system, could be extended to a higher energy regime, which is useful for analyzing the physics of the Kondo transport in non-equilibrium or high temperature cases.

  14. Corrected Kondo temperature beyond the conventional Kondo scaling limit.

    Science.gov (United States)

    Li, ZhenHua; Wei, JianHua; Zheng, Xiao; Yan, YiJing; Luo, Hong-Gang

    2017-02-20

    In the Kondo systems such as the magnetic impurity screened by the conduction electrons in a metal host, as well as the quantum dots connected by the leads, the low energy behaviors have universal dependence on the [Formula: see text] or [Formula: see text], where [Formula: see text] is the conventional Kondo temperature. However, it was shown that this scaling behavior is only valid at low-energy; this is called the Kondo scaling limit. Here we explore the extention of the scaling parameter range by introducing the corrected Kondo temperature T K, which may depend on the temperature and bias, as well as the other external parameters. We define the corrected Kondo temperature by scaling the local density of states near the Fermi level, obtained by accurate hierarchy of equations of motion approach at finite temperature and finite bias, and thus obtain a phenomenological expression of the corrected Kondo temperature. By using the corrected Kondo temperature as a characteristic energy scale, the conductance of the quantum dot can be well scaled in a wide parameter range, even two orders beyond the conventional scaling parameter range. Our work indicates that the Kondo scaling, although dominated by the conventional Kondo temperature in the low-energy of the Kondo system, could be extended to a higher energy regime, which is useful for analyzing the physics of the Kondo transport in non-equilibrium or high temperature cases.

  15. Correlation Analysis of some Growth, Yield, Yield Components and ...

    African Journals Online (AJOL)

    Keywords: Correlation, Wheat; growth, yield, yield components, grain quality. INTRODUCTION. Wheat ... macaroni, biscuits, cookies, cakes, pasta, noodles and couscous; beer, many .... and 6 WAS which ensured weed free plots. Fertilizer was ...

  16. Energy balance in IPM rice farms compared to conventional farms

    Directory of Open Access Journals (Sweden)

    Mehdi Fazeli

    2017-06-01

    Full Text Available Integrated Pest Management based on Farmer Field Schools (IPM/FFS is a program aimed to guide farmers toward managing agricultural pests in an environmentally responsible manner. This program has been in practice during the recent decade in the north of Iran. A study was conducted to evaluate the overall impacts of IPM/FFS program on energy balance and economic revenue of paddy (Oryza sativa L. farms compared with conventional farms (no IPM. The data of inputs, management practices, and output (yield of 238 paddy farms (135 IPM farms and 103 conventional farms located in a semi-Mediterranean climate were collected in 2010 and 2011. Total energy input, energy output, energy efficiency, and energy productivity were determined as indicators of energy balance. The total energy requirement for paddy production in IPM system was 48756 MJ ha−1, indicating that 8% more energy was used in IPM farms than that in conventional farms. It was noticed that IPM program in this region failed to reduce the consumption of chemical pesticides in paddy farms and the conventional system was more energy efficient than IPM system. Although paddy yield of the two systems was similar, the economic net return in IPM system was almost 20% higher than the conventional system due to the higher price of paddy produced in IPM system.

  17. Quantum weirdness

    CERN Document Server

    Mullin, William J

    2017-01-01

    Quantum mechanics allows a remarkably accurate description of nature and powerful predictive capabilities. The analyses of quantum systems and their interpretation lead to many surprises, for example, the ability to detect the characteristics of an object without ever touching it in any way, via "interaction-free measurement," or the teleportation of an atomic state over large distances. The results can become downright bizarre. Quantum mechanics is a subtle subject that usually involves complicated mathematics -- calculus, partial differential equations, etc., for complete understanding. Most texts for general audiences avoid all mathematics. The result is that the reader misses almost all deep understanding of the subject, much of which can be probed with just high-school level algebra and trigonometry. Thus, readers with that level of mathematics can learn so much more about this fundamental science. The book starts with a discussion of the basic physics of waves (an appendix reviews some necessary class...

  18. Quantum mechanics

    CERN Document Server

    Fitzpatrick, Richard

    2015-01-01

    Quantum mechanics was developed during the first few decades of the twentieth century via a series of inspired guesses made by various physicists, including Planck, Einstein, Bohr, Schroedinger, Heisenberg, Pauli, and Dirac. All these scientists were trying to construct a self-consistent theory of microscopic dynamics that was compatible with experimental observations. The purpose of this book is to present quantum mechanics in a clear, concise, and systematic fashion, starting from the fundamental postulates, and developing the theory in as logical manner as possible. Topics covered in the book include the fundamental postulates of quantum mechanics, angular momentum, time-dependent and time-dependent perturbation theory, scattering theory, identical particles, and relativistic electron theory.

  19. Quantum spirals

    CERN Document Server

    Yoshida, Z

    2016-01-01

    Quantum systems often exhibit fundamental incapability to entertain vortex. The Meissner effect, a complete expulsion of the magnetic field (the electromagnetic vorticity), for instance, is taken to be the defining attribute of the superconducting state. Superfluidity is another, close-parallel example; fluid vorticity can reside only on topological defects with a limited (quantized) amount. Recent developments in the Bose-Einstein condensates produced by particle traps further emphasize this characteristic. We show that the challenge of imparting vorticity to a quantum fluid can be met through a nonlinear mechanism operating in a hot fluid corresponding to a thermally modified Pauli-Schroedinger spinor field. In a simple field-free model, we show that the thermal effect, represented by a nonlinear, non-Hermitian Hamiltonian, in conjunction with spin vorticity, leads to new interesting quantum states; a spiral solution is explicitly worked out.

  20. Quantum waveguides

    CERN Document Server

    Exner, Pavel

    2015-01-01

    This monograph explains the theory of quantum waveguides, that is, dynamics of quantum particles confined to regions in the form of tubes, layers, networks, etc. The focus is on relations between the confinement geometry on the one hand and the spectral and scattering properties of the corresponding quantum Hamiltonians on the other. Perturbations of such operators, in particular, by external fields are also considered. The volume provides a unique summary of twenty five years of research activity in this area and indicates ways in which the theory can develop further. The book is fairly self-contained. While it requires some broader mathematical physics background, all the basic concepts are properly explained and proofs of most theorems are given in detail, so there is no need for additional sources. Without a parallel in the literature, the monograph by Exner and Kovarik guides the reader through this new and exciting field.