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Sample records for two-dimensional infrared 2dir

  1. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

    Science.gov (United States)

    Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

    2017-03-01

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

  2. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

    Science.gov (United States)

    Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

    2017-03-05

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Measuring protein dynamics with ultrafast two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    Adamczyk, Katrin; Candelaresi, Marco; Hunt, Neil T; Robb, Kirsty; Hoskisson, Paul A; Tucker, Nicholas P; Gumiero, Andrea; Walsh, Martin A; Parker, Anthony W

    2012-01-01

    Recent advances in the methodology and application of ultrafast two-dimensional infrared (2D-IR) spectroscopy to biomolecular systems are reviewed. A description of the 2D-IR technique and the molecular contributions to the observed spectra are presented followed by a discussion of recent literature relating to the use of 2D-IR and associated approaches for measuring protein dynamics. In particular, these include the use of diatomic ligand groups for measuring haem protein dynamics, isotopic labelling strategies and the use of vibrational probe groups. The final section reports on the current state of the art regarding the use of 2D-IR methods to provide insights into biological reaction mechanisms. (topical review)

  4. Waiting Time Dynamics in Two-Dimensional Infrared Spectroscopy

    NARCIS (Netherlands)

    Jansen, Thomas L. C.; Knoester, Jasper

    We review recent work on the waiting time dynamics of coherent two-dimensional infrared (2DIR) spectroscopy. This dynamics can reveal chemical and physical processes that take place on the femto- and picosecond time scale, which is faster than the time scale that may be probed by, for example,

  5. Proton transport in a membrane protein channel: two-dimensional infrared spectrum modeling.

    NARCIS (Netherlands)

    Liang, C.; Knoester, J.; Jansen, T.L.Th.A.

    2012-01-01

    We model the two-dimensional infrared (2DIR) spectrum of a proton channel to investigate its applicability as a spectroscopy tool to study the proton transport process in biological systems. Proton transport processes in proton channels are involved in numerous fundamental biochemical reactions.

  6. A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Vogt, Tim; Winter, Ernst; Bredenbeck, Jens, E-mail: bredenbeck@biophysik.uni-frankfurt.org, E-mail: bredenbeck@biophysik.uni-frankfurt.de [Institut für Biophysik, Johann Wolfgang Goethe-Universität, Max-von-Laue-Strasse 1, 60438 Frankfurt (Germany)

    2015-08-15

    A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported.

  7. A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Vogt, Tim; Winter, Ernst; Bredenbeck, Jens

    2015-01-01

    A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported

  8. Study on Senna alata and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation infrared spectroscopy

    Science.gov (United States)

    Adiana, M. A.; Mazura, M. P.

    2011-04-01

    Senna alata L. commonly known as candle bush belongs to the family of Fabaceae and the plant has been reported to possess anti-inflammatory, analgesic, laxative and antiplatelet-aggregating activity. In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional infrared correlation spectroscopy (2D-IR) to study the main constituents of S. alata and its different extracts (extracted by hexane, dichloromethane, ethyl acetate and methanol in turn). The findings indicated that FT-IR and 2D-IR can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can identify the main chemical constituents in medicinal materials and their extracts, but also compare the components differences among similar samples. In a conclusion, FT-IR spectroscopy combined with 2D correlation analysis provides a powerful method for the quality control of traditional medicines.

  9. Ultrafast Two-Dimensional Infrared Spectroscopy of a Quasifree Rotor: J Scrambling and Perfectly Anticorrelated Cross Peaks

    Science.gov (United States)

    Mandal, Aritra; Ng Pack, Greg; Shah, Parth P.; Erramilli, Shyamsunder; Ziegler, L. D.

    2018-03-01

    Ultrafast two-dimensional infrared (2DIR) spectra of the N2O ν3 mode in moderately dense SF6 gas exhibit complex line shapes with diagonal and antidiagonal features in contrast to condensed phase vibrational 2DIR spectroscopy. Observed spectra for this quasifree rotor system are well captured by a model that includes all 36 possible rovibrational pathways and treats P (Δ J =-1 ) and R (Δ J =+1 ) branch resonances as distinct Kubo line shape features. Transition frequency correlation decay is due to J scrambling within one to two gas collisions at each density. Studies of supercritical solvation and relaxation at high pressure and temperature are enabled by this methodology.

  10. Study on Angelica and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

    Science.gov (United States)

    Liu, Hong-xia; Sun, Su-qin; Lv, Guang-hua; Chan, Kelvin K. C.

    2006-05-01

    In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy (2D-IR) to study the main constituents in traditional Chinese medicine Angelica and its different extracts (extracted by petroleum ether, ethanol and water in turn). The findings indicated that FT-IR spectrum can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can not only identify the main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. This analytical method is highly rapid, effective, visual and accurate for pharmaceutical research.

  11. The structure of salt bridges between Arg(+) and Glu(-) in peptides investigated with 2D-IR spectroscopy: Evidence for two distinct hydrogen-bond geometries.

    Science.gov (United States)

    Huerta-Viga, Adriana; Amirjalayer, Saeed; Domingos, Sérgio R; Meuzelaar, Heleen; Rupenyan, Alisa; Woutersen, Sander

    2015-06-07

    Salt bridges play an important role in protein folding and in supramolecular chemistry, but they are difficult to detect and characterize in solution. Here, we investigate salt bridges between glutamate (Glu(-)) and arginine (Arg(+)) using two-dimensional infrared (2D-IR) spectroscopy. The 2D-IR spectrum of a salt-bridged dimer shows cross peaks between the vibrational modes of Glu(-) and Arg(+), which provide a sensitive structural probe of Glu(-)⋯Arg(+) salt bridges. We use this probe to investigate a β-turn locked by a salt bridge, an α-helical peptide whose structure is stabilized by salt bridges, and a coiled coil that is stabilized by intra- and intermolecular salt bridges. We detect a bidentate salt bridge in the β-turn, a monodentate one in the α-helical peptide, and both salt-bridge geometries in the coiled coil. To our knowledge, this is the first time 2D-IR has been used to probe tertiary side chain interactions in peptides, and our results show that 2D-IR spectroscopy is a powerful method for investigating salt bridges in solution.

  12. Towards a Molecular Movie: Real Time Observation of Hydrogen Bond Breaking by Transient 2D-IR Spectroscopy in a Cyclic Peptide

    Science.gov (United States)

    Kolano, Christoph; Helbing, Jan; Sander, Wolfram; Hamm, Peter

    Transient two-dimensional infrared spectroscopy (T2D-IR) has been used to observe in real time the non-equilibrium structural dynamics of intramolecular hydrogen bond breaking in a small cyclic disulfide-bridged peptide.

  13. Acid-base equilibrium dynamics in methanol and dimethyl sulfoxide probed by two-dimensional infrared spectroscopy.

    Science.gov (United States)

    Lee, Chiho; Son, Hyewon; Park, Sungnam

    2015-07-21

    Two-dimensional infrared (2DIR) spectroscopy, which has been proven to be an excellent experimental method for studying thermally-driven chemical processes, was successfully used to investigate the acid dissociation equilibrium of HN3 in methanol (CH3OH) and dimethyl sulfoxide (DMSO) for the first time. Our 2DIR experimental results indicate that the acid-base equilibrium occurs on picosecond timescales in CH3OH but that it occurs on much longer timescales in DMSO. Our results imply that the different timescales of the acid-base equilibrium originate from different proton transfer mechanisms between the acidic (HN3) and basic (N3(-)) species in CH3OH and DMSO. In CH3OH, the acid-base equilibrium is assisted by the surrounding CH3OH molecules which can directly donate H(+) to N3(-) and accept H(+) from HN3 and the proton migrates through the hydrogen-bonded chain of CH3OH. On the other hand, the acid-base equilibrium in DMSO occurs through the mutual diffusion of HN3 and N3(-) or direct proton transfer. Our 2DIR experimental results corroborate different proton transfer mechanisms in the acid-base equilibrium in protic (CH3OH) and aprotic (DMSO) solvents.

  14. Two-dimensional correlation infrared spectroscopy applied to analyzing and identifying the extracts of Baeckea frutescens medicinal materials.

    Science.gov (United States)

    Adib, Adiana Mohamed; Jamaludin, Fadzureena; Kiong, Ling Sui; Hashim, Nuziah; Abdullah, Zunoliza

    2014-08-05

    Baeckea frutescens or locally known as Cucur atap is used as antibacterial, antidysentery, antipyretic and diuretic agent. In Malaysia and Indonesia, they are used as an ingredient of the traditional medicine given to mothers during confinement. A three-steps infra-red (IR) macro-fingerprinting method combining conventional IR spectra, and the secondary derivative spectra with two dimensional infrared correlation spectroscopy (2D-IR) have been proved to be effective methods to examine a complicated mixture such as herbal medicines. This study investigated the feasibility of employing multi-steps IR spectroscopy in order to study the main constituents of B. frutescens and its different extracts (extracted by chloroform, ethyl acetate, methanol and aqueous in turn). The findings indicated that FT-IR and 2D-IR can provide many holistic variation rules of chemical constituents. The structural information of the samples indicated that B. frutescens and its extracts contain a large amount of flavonoids, since some characteristic absorption peaks of flavonoids, such as ∼1600cm(-1), ∼1500cm(-1), ∼1450cm(-1), and ∼1270cm(-1) can be observed. The macroscopical fingerprint characters of FT-IR and 2D-IR spectra can not only provide the information of main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Revealing the Solvation Structure and Dynamics of Carbonate Electrolytes in Lithium-Ion Batteries by Two-Dimensional Infrared Spectrum Modeling.

    Science.gov (United States)

    Liang, Chungwen; Kwak, Kyungwon; Cho, Minhaeng

    2017-12-07

    Carbonate electrolytes in lithium-ion batteries play a crucial role in conducting lithium ions between two electrodes. Mixed solvent electrolytes consisting of linear and cyclic carbonates are commonly used in commercial lithium-ion batteries. To understand how the linear and cyclic carbonates introduce different solvation structures and dynamics, we performed molecular dynamics simulations of two representative electrolyte systems containing either linear or cyclic carbonate solvents. We then modeled their two-dimensional infrared (2DIR) spectra of the carbonyl stretching mode of these carbonate molecules. We found that the chemical exchange process involving formation and dissociation of lithium-ion/carbonate complexes is responsible for the growth of 2DIR cross peaks with increasing waiting time. In addition, we also found that cyclic carbonates introduce faster dynamics of dissociation and formation of lithium-ion/carbonate complexes than linear carbonates. These findings provide new insights into understanding the lithium-ion mobility and its interplay with solvation structure and ultrafast dynamics in carbonate electrolytes used in lithium-ion batteries.

  16. Two-dimensional vibrational spectroscopy of the amide I band of crystalline acetanilide: Fermi resonance, conformational substates, or vibrational self-trapping?

    Science.gov (United States)

    Edler, J.; Hamm, P.

    2003-08-01

    Two-dimensional infrared (2D-IR) spectroscopy is applied to investigate acetanilide, a molecular crystal consisting of quasi-one-dimensional hydrogen bonded peptide units. The amide-I band exhibits a double peak structure, which has been attributed to different mechanisms including vibrational self-trapping, a Fermi resonance, or the existence of two conformational substates. The 2D-IR spectrum of crystalline acetanilide is compared with that of two different molecular systems: (i) benzoylchloride, which exhibits a strong symmetric Fermi resonance and (ii) N-methylacetamide dissolved in methanol which occurs in two spectroscopically distinguishable conformations. Both 2D-IR spectra differ significantly from that of crystalline acetanilide, proving that these two alternative mechanisms cannot account for the anomalous spectroscopy of crystalline acetanilide. On the other hand, vibrational self-trapping of the amide-I band can naturally explain the 2D-IR response.

  17. Verification of Ganoderma (lingzhi) commercial products by Fourier Transform infrared spectroscopy and two-dimensional IR correlation spectroscopy

    Science.gov (United States)

    Choong, Yew-Keong; Sun, Su-Qin; Zhou, Qun; Lan, Jin; Lee, Han-Lim; Chen, Xiang-Dong

    2014-07-01

    Ganoderma commercial products are typically based on two sources, raw material (powder form and/or spores) and extract (water and/or solvent). This study compared three types of Ganoderma commercial products using 1 Dimensional Fourier Transform infrared and second derivative spectroscopy. The analyzed spectra of Ganoderma raw material products were compared with spectra of cultivated Ganoderma raw material powder from different mushroom farms in Malaysia. The Ganoderma extract product was also compared with three types of cultivated Ganoderma extracts. Other medicinal Ganoderma contents in commercial extract product that included glucan and triterpenoid were analyzed by using FTIR and 2DIR. The results showed that water extract of cultivated Ganoderma possessed comparable spectra with that of Ganoderma product water extract. By comparing the content of Ganoderma commercial products using FTIR and 2DIR, product content profiles could be detected. In addition, the geographical origin of the Ganoderma products could be verified by comparing their spectra with Ganoderma products from known areas. This study demonstrated the possibility of developing verification tool to validate the purity of commercial medicinal herbal and mushroom products.

  18. Development of the relaxation-assisted 2DIR method for accessing structures of molecules and its application for studying the energy transport on a molecular level

    Science.gov (United States)

    Kasyanenko, Valeriy Mitrofanovich

    Measuring the three-dimensional structure of molecules, dynamics of structural changes, and energy transport on a molecular scale is important for many areas of natural science. Supplementing the widely used methods of x-ray diffraction, NMR, and optical spectroscopies, a two-dimensional infrared spectroscopy (2DIR) method was introduced about a decade ago. The 2DIR method measures pair-wise interactions between vibrational modes in molecules, thus acquiring molecular structural constraints such as distances between vibrating groups and the angles between their transition dipoles. The 2DIR method has been applied to a variety of molecular systems but in studying larger molecules such as proteins and peptides the method is facing challenges associated with the congestion of their vibrational spectra and delocalized character of their vibrational modes. To help extract structural information from such spectra and make efficient use of vibrational modes separated by large distances, a novel relaxation-assisted 2DIR method (RA 2DIR) has recently been proposed, which exploits the transport of excess vibrational energy from the initially excited mode. With the goal of further development of RA 2DIR, we applied it to a variety of molecular systems, including model compounds, transition-metal complexes, and isomers. The experiments revealed several novel effects which both enhance the power of RA 2DIR and bring a deeper understanding to the fundamental process of energy transport on a molecular level. We demonstrated that RA 2DIR can enhance greatly (27-fold) the cross-peak amplitude among spatially remote modes, which leads to an increase of the range of distances accessible for structural measurements by several fold. We demonstrated that the energy transport time correlates with the intermode distance. This correlation offers a new way for identifying connectivity patterns in molecules. We developed two models of energy transport in molecules. In one, a spatial overlap

  19. Ultrafast internal rotational dynamics of the azido group in (4S)-azidoproline: Chemical exchange 2DIR spectroscopic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung-Koo; Park, Kwang-Hee; Joo, Cheonik; Kwon, Hyeok-Jun; Han, Hogyu [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of); Ha, Jeong-Hyon [Multidimensional Spectroscopy Laboratory, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of); Park, Sungnam, E-mail: spark8@korea.ac.kr [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of); Multidimensional Spectroscopy Laboratory, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of); Cho, Minhaeng, E-mail: mcho@korea.ac.kr [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of); Multidimensional Spectroscopy Laboratory, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of); Research Institute for Natural Sciences, Korea University, Seoul 136-713 (Korea, Republic of)

    2012-03-02

    Graphical abstract: Internal rotational dynamics of the azido group in SA (Ac-(4S)-Azp-NHMe) was studied in real time by using ultrafast 2DIR spectroscopic method. The time constant of the internal rotation around the C{sup {gamma}}-N{sup {delta}} bond in SA was determined to be {tau}{sub ir} = 5.1 ps, which is found to be much faster than that around the C-C bond in ethane. Highlights: Black-Right-Pointing-Pointer Femtosecond two-dimensional IR spectroscopy of internal rotational dynamics. Black-Right-Pointing-Pointer Stereo-electronic effects of azido group in azido-derivatized proline peptide. Black-Right-Pointing-Pointer The timescale of the azido group internal rotation is about 5.1 ps. - Abstract: The azido group in 4-azidoproline (Azp) derivative, SA (Ac-(4S)-Azp-NHMe), can form an intramolecular electrostatic interaction with the backbone peptide in the s-trans and C{sup {gamma}}-endo conformations of SA. As a result, the azido group exists as two forms, bound and free, which are defined by the presence and absence of such interaction, respectively. The bound and free azido forms are spectrally resolved in the azido IR spectrum of SA in CHCl{sub 3}. Using the two-dimensional infrared (2DIR) and polarization-controlled IR pump-probe methods, we investigated the internal rotational and orientational relaxation dynamics of the azido group and determined the internal rotational time constant of the azido group to be 5.1 ps. The internal rotational motion is found to be responsible for the early part of the orientational relaxation of the azido group in SA. Thus, the femtosecond 2DIR spectroscopy is shown to be an ideal tool for studying ultrafast conformational dynamics of SA.

  20. IL 6: 2D-IR spectroscopy: chemistry and biophysics in real time

    International Nuclear Information System (INIS)

    Bredenbeck, Jens

    2010-01-01

    Pulsed multidimensional experiments, daily business in the field of NMR spectroscopy, have been demonstrated only relatively recently in IR spectroscopy. Similar as nuclear spins in multidimensional NMR, molecular vibrations are employed in multidimensional IR experiments as probes of molecular structure and dynamics, albeit with femtosecond time resolution. Different types of multidimensional IR experiments have been implemented, resembling basic NMR experiments such as NOESY, COSY and EXSY. In contrast to one-dimensional linear spectroscopy, such multidimensional experiments reveal couplings and correlations of vibrations, which are closely linked to molecular structure and its change in time. The use of mixed IR/VIS pulse sequences further extends the potential of multidimensional IR spectroscopy, enabling studies of ultrafast non-equilibrium processes as well as surface specific, highly sensitive experiments. A UV/VIS pulse preceding the IR pulse sequence can be used to prepare the system under study in a non-equilibrium state. 2D-IR snapshots of the evolving non-equilibrium system are then taken, for example during a photochemical reaction or during the photo-cycle of a light sensitive protein. Preparing the system in a non-equilibrium state by UV/Vis excitation during the IR pulse sequence allows for correlating states of reactant and product of the light triggered process via their 2D-IR cross peaks - a technique that has been used to map the connectivity between different binding sites of a ligand as it migrates through a protein. Introduction of a non-resonant VIS pulse at the end of the IR part of the experiment allows to selectively up-convert the infrared signal of interfacial molecules to the visible spectral range by sum frequency generation. In this way, femtosecond interfacial 2D-IR spectroscopy can be implemented, achieving sub-monolayer sensitivity. (author)

  1. Differentiation and quality estimation of Cordyceps with infrared spectroscopy

    Science.gov (United States)

    Yang, Ping; Song, Ping; Sun, Su-Qin; Zhou, Qun; Feng, Shu; Tao, Jia-Xun

    2009-11-01

    Heretofore, a scientific and systemic method for differentiation and quality estimation of a well-known Chinese traditional medicine, 'Cordyceps', has not been established in modern market. In this paper, Fourier-transform infrared spectroscopy (FTIR) and two-dimensional correlation infrared spectroscopy (2D-IR) are employed to propose a method for analysis of Cordyceps. It has presented that IR spectra of real Cordyceps of different origins and counterfeits have their own macroscopic fingerprints, with discriminated shapes, positions and intensities. Their secondary derivative spectra can amplify the differences and confirm the potentially characteristic IR absorption bands 1400-1700 cm -1 to be investigated in 2D-IR. Many characteristic fingerprints are discovered in 2D-IR spectra in the range of 1400-1700 cm -1 and hetero 2D spectra of 670-780 cm -1 × 1400-1700 cm -1. The different fingerprints display different chemical constitutes. Through the three steps, different Cordyceps and their counterfeits can be discriminated effectively and their qualities distinctly display. Successful analysis of eight Cordyceps capsule products has proved the practicability of the method, which can also be applied to the quality estimation of other Chinese traditional medicines.

  2. Ultrafast vibrational spectroscopy (2D-IR) of CO{sub 2} in ionic liquids: Carbon capture from carbon dioxide’s point of view

    Energy Technology Data Exchange (ETDEWEB)

    Brinzer, Thomas; Berquist, Eric J.; Ren, Zhe; Dutta, Samrat; Johnson, Clinton A.; Krisher, Cullen S.; Lambrecht, Daniel S.; Garrett-Roe, Sean, E-mail: sgr@pitt.edu [Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260 (United States)

    2015-06-07

    The CO{sub 2}ν{sub 3} asymmetric stretching mode is established as a vibrational chromophore for ultrafast two-dimensional infrared (2D-IR) spectroscopic studies of local structure and dynamics in ionic liquids, which are of interest for carbon capture applications. CO{sub 2} is dissolved in a series of 1-butyl-3-methylimidazolium-based ionic liquids ([C{sub 4}C{sub 1}im][X], where [X]{sup −} is the anion from the series hexafluorophosphate (PF{sub 6}{sup −}), tetrafluoroborate (BF{sub 4}{sup −}), bis-(trifluoromethyl)sulfonylimide (Tf{sub 2}N{sup −}), triflate (TfO{sup −}), trifluoroacetate (TFA{sup −}), dicyanamide (DCA{sup −}), and thiocyanate (SCN{sup −})). In the ionic liquids studied, the ν{sub 3} center frequency is sensitive to the local solvation environment and reports on the timescales for local structural relaxation. Density functional theory calculations predict charge transfer from the anion to the CO{sub 2} and from CO{sub 2} to the cation. The charge transfer drives geometrical distortion of CO{sub 2}, which in turn changes the ν{sub 3} frequency. The observed structural relaxation timescales vary by up to an order of magnitude between ionic liquids. Shoulders in the 2D-IR spectra arise from anharmonic coupling of the ν{sub 2} and ν{sub 3} normal modes of CO{sub 2}. Thermal fluctuations in the ν{sub 2} population stochastically modulate the ν{sub 3} frequency and generate dynamic cross-peaks. These timescales are attributed to the breakup of ion cages that create a well-defined local environment for CO{sub 2}. The results suggest that the picosecond dynamics of CO{sub 2} are gated by local diffusion of anions and cations.

  3. Discrimination of different red wine by Fourier-transform infrared and two-dimensional infrared correlation spectroscopy

    Science.gov (United States)

    Zhang, Yan-ling; Chen, Jian-bo; Lei, Yu; Zhou, Qun; Sun, Su-qin; Noda, Isao

    2010-06-01

    Fourier-transform infrared spectroscopy (FT-IR) and two-dimensional infrared (2D IR) correlation spectroscopy were applied to analyze main components of liquid red wine with different sugar contents and volatilization residues of dry red wine from different manufactures. The infrared spectra, second derivative spectra of dry red wine show the typical peaks of alcohol, while the spectra of sweet wine are composed of the peaks of both alcohol and sugar, and the contribution of sugar enhanced as the increase of sugar content. Using principal component analysis (PCA) method, dry and sweet wine can be readily classified. Analysis of the infrared spectra of the volatilization residues of dry red wine samples from five different manufactures indicates that dry red wine may be composed of glycerol, carboxylic acids or esters and carboxyl ate, at the same time, different dry red wine show different characteristic peaks in the second derivative spectra and 2D IR correlation spectra, which can be used to discriminate the different manufactures and evaluate the quality of wine samples. The results suggested that infrared spectroscopy is a direct and effective method for the analysis of principle components of different red wines and discrimination of different red wines.

  4. [Infrared spectroscopic analysis of Guilin watermelon frost products].

    Science.gov (United States)

    Huang, Dong-lan; Chen, Xiao-kang; Xu, Yong-qun; Sun, Su-qin; Zhou, Qun; Lu, Wen-guan

    2012-08-01

    The objective of the present study is to analyze different products of Guilin watermelon frost by Fourier transform infrared spectroscopy (FTIR), second derivative infrared spectroscopy and two-dimensional correlation spectroscopy (2D-IR) under thermal perturbation. The structural information of the samples indicates that samples from the same factory but of different brands had some dissimilarities in the IR spectra, and the type and content of accessories of them were different compared with conventional IR spectra of samples, peaks at 638 and 616 cm(-1) all arise from anhydrous sodium sulfate in watermelon frost spray and watermelon frost capsule; the characteristic absorption peaks of the sucrose, dextrin or other accessories can be seen clearly in the spectra of watermelon frost throat-clearing buccal tablets, watermelon frost throat tablets and watermelon frost lozenge. And the IR spectra of watermelon frost lozenge is very similar to the IR spectra of sucrose, so it can be easily proved that the content of sucrose in watermelon frost lozenge is high. In the 2D-IR correlation spectra, the samples presented the differences in the position, number and relative intensity of autopeaks and correlation peak clusters. Consequently, the macroscopical fingerprint characters of FTIR, second derivative infrared spectra and 2D-IR spectra can not only provide the information about main chemical constituents in medical materials, but also analyze and identify the type and content of accessories in Guilin watermelon frost. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research.

  5. Two-Dimensional SiO2/VO2 Photonic Crystals with Statically Visible and Dynamically Infrared Modulated for Smart Window Deployment.

    Science.gov (United States)

    Ke, Yujie; Balin, Igal; Wang, Ning; Lu, Qi; Tok, Alfred Iing Yoong; White, Timothy J; Magdassi, Shlomo; Abdulhalim, Ibrahim; Long, Yi

    2016-12-07

    Two-dimensional (2D) photonic structures, widely used for generating photonic band gaps (PBG) in a variety of materials, are for the first time integrated with the temperature-dependent phase change of vanadium dioxide (VO 2 ). VO 2 possesses thermochromic properties, whose potential remains unrealized due to an undesirable yellow-brown color. Here, a SiO 2 /VO 2 core/shell 2D photonic crystal is demonstrated to exhibit static visible light tunability and dynamic near-infrared (NIR) modulation. Three-dimensional (3D) finite difference time domain (FDTD) simulations predict that the transmittance can be tuned across the visible spectrum, while maintaining good solar regulation efficiency (ΔT sol = 11.0%) and high solar transmittance (T lum = 49.6%). Experiments show that the color changes of VO 2 films are accompanied by NIR modulation. This work presents a novel way to manipulate VO 2 photonic structures to modulate light transmission as a function of wavelength at different temperatures.

  6. Discriminating trpzip2 and trpzip4 peptides’ folding landscape using the two-dimensional infrared spectroscopy: A simulation study

    International Nuclear Information System (INIS)

    Wu, Tianmin; Zhang, Ruiting; Li, Huanhuan; Zhuang, Wei; Yang, Lijiang

    2014-01-01

    We analyzed, based on the theoretical spectroscopic modeling, how the differences in the folding landscapes of two β-hairpin peptides trpzip2 and trpzip4 are reflected in their thermal unfolding infrared measurements. The isotope-edited equilibrium FTIR and two dimensional infrared spectra of the two peptides were calculated, using the nonlinear exciton propagation method, at a series of temperatures. The spectra calculations were based on the configuration distributions generated using the GB OBC implicit solvent MD simulation and the integrated tempering sampling technique. Conformational analysis revealed the different local thermal stabilities for these two peptides, which suggested the different folding landscapes. Our study further suggested that the ellipticities of the isotope peaks in the coherent IR signals are more sensitive to these local stability differences compared with other spectral features such as the peak intensities. Our technique can thus be combined with the relevant experimental measurements to achieve a better understanding of the peptide folding behaviors

  7. Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cahoon, James Francis [Univ. of California, Berkeley, CA (United States)

    2008-12-01

    One and two dimensional time-resolved vibrational spectroscopy has been used to investigate the elementary reactions of several prototypical organometallic complexes in room temperature solution. The electron transfer and ligand substitution reactions of photogenerated 17-electron organometallic radicals CpW(CO)3 and CpFe(CO)2 have been examined with one dimensional spectroscopy on the picosecond through microsecond time-scales, revealing the importance of caging effects and odd-electron intermediates in these reactions. Similarly, an investigation of the photophysics of the simple Fischer carbene complex Cr(CO)5[CMe(OMe)] showed that this class of molecule undergoes an unusual molecular rearrangement on the picosecond time-scale, briefly forming a metal-ketene complex. Although time-resolved spectroscopy has long been used for these types of photoinitiated reactions, the advent of two dimensional vibrational spectroscopy (2D-IR) opens the possibility to examine the ultrafast dynamics of molecules under thermal equilibrium conditions. Using this method, the picosecond fluxional rearrangements of the model metal carbonyl Fe(CO)5 have been examined, revealing the mechanism, time-scale, and transition state of the fluxional reaction. The success of this experiment demonstrates that 2D-IR is a powerful technique to examine the thermally-driven, ultrafast rearrangements of organometallic molecules in solution.

  8. Analysis and identification of two similar traditional Chinese medicines by using a three-stage infrared spectroscopy: Ligusticum chuanxiong, Angelica sinensis and their different extracts

    Science.gov (United States)

    Xiang, Li; Wang, Jingjuan; Zhang, Guijun; Rong, Lixin; Wu, Haozhong; Sun, Suqin; Guo, Yizhen; Yang, Yanfang; Lu, Lina; Qu, Lei

    2016-11-01

    Rhizoma Chuanxiong (CX) and Radix Angelica sinensis (DG) are very important Traditional Chinese Medicine (TCM) and usually used in clinic. They both are from the Umbelliferae family, and have almost similar chemical constituents with each other. It is complicated, time-consuming and laborious to discriminate them by using the chromatographic methods such as high performance liquid chromatography (HPLC) and gas chromatography (GC). Therefore, to find a fast, applicable and effective identification method for two herbs is urged in quality research of TCM. In this paper, by using a three-stage infrared spectroscopy (Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2D-IR)), we analyzed and discriminated CX, DG and their different extracts (aqueous extract, alcoholic extract and petroleum ether extract). In FT-IR, all the CX and DG samples' spectra seemed similar, but they had their own unique macroscopic fingerprints to identify. Through comparing with the spectra of sucrose and the similarity calculation, we found the content of sucrose in DG raw materials was higher than in CX raw materials. The significant differences in alcoholic extract appeared that in CX alcoholic extract, the peaks at 1743 cm-1 was obviously stronger than the peak at same position in DG alcoholic extract. Besides in petroleum ether extract, we concluded CX contained much more ligustilide than DG by the similarity calculation. With the function of SD-IR, some tiny differences were amplified and overlapped peaks were also unfolded in FT-IR. In the range of 1100-1175 cm-1, there were six peaks in the SD-IR spectra of DG and the intensity, shape and location of those six peaks were similar to that of sucrose, while only two peaks could be observed in that of CX and those two peaks were totally different from sucrose in shape and relative intensity. This result was consistent with that of the

  9. Method for generation of tunable far infrared radiation from two-dimensional plasmons

    Science.gov (United States)

    Katz, Joseph (Inventor)

    1989-01-01

    Tunable far infrared radiation is produced from two-dimensional plasmons in a heterostructure, which provides large inversion-layer electron densities at the heterointerface, without the need for a metallic grating to couple out the radiation. Instead, a light interference pattern is produced on the planar surface of the heterostructure using two coherent laser beams of a wavelength selected to be strongly absorbed by the heterostructure in order to penetrate through the inversion layer. The wavelength of the far infrared radiation coupled out can then be readily tuned by varying the angle between the coherent beams, or varying the wavelength of the two interfering coherent beams, thus varying the periodicity of the photoconductivity grating to vary the wavelength of the far infrared radiation being coupled out.

  10. Solute-solvent complex switching dynamics of chloroform between acetone and dimethylsulfoxide-two-dimensional IR chemical exchange spectroscopy.

    Science.gov (United States)

    Kwak, Kyungwon; Rosenfeld, Daniel E; Chung, Jean K; Fayer, Michael D

    2008-11-06

    Hydrogen bonds formed between C-H and various hydrogen bond acceptors play important roles in the structure of proteins and organic crystals, and the mechanisms of C-H bond cleavage reactions. Chloroform, a C-H hydrogen bond donor, can form weak hydrogen-bonded complexes with acetone and with dimethylsulfoxide (DMSO). When chloroform is dissolved in a mixed solvent consisting of acetone and DMSO, both types of hydrogen-bonded complexes exist. The two complexes, chloroform-acetone and chloroform-DMSO, are in equilibrium, and they rapidly interconvert by chloroform exchanging hydrogen bond acceptors. This fast hydrogen bond acceptor substitution reaction is probed using ultrafast two-dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy. Deuterated chloroform is used in the experiments, and the 2D-IR spectrum of the C-D stretching mode is measured. The chemical exchange of the chloroform hydrogen bonding partners is tracked by observing the time-dependent growth of off-diagonal peaks in the 2D-IR spectra. The measured substitution rate is 1/30 ps for an acetone molecule to replace a DMSO molecule in a chloroform-DMSO complex and 1/45 ps for a DMSO molecule to replace an acetone molecule in a chloroform-acetone complex. Free chloroform exists in the mixed solvent, and it acts as a reactive intermediate in the substitution reaction, analogous to a SN1 type reaction. From the measured rates and the equilibrium concentrations of acetone and DMSO, the dissociation rates for the chloroform-DMSO and chloroform-acetone complexes are found to be 1/24 ps and 1/5.5 ps, respectively. The difference between the measured rate for the complete substitution reaction and the rate for complex dissociation corresponds to the diffusion limited rate. The estimated diffusion limited rate agrees well with the result from a Smoluchowski treatment of diffusive reactions.

  11. Quantum Dots in Two-Dimensional Perovskite Matrices for Efficient Near-Infrared Light Emission

    KAUST Repository

    Yang, Zhenyu

    2017-03-13

    Quantum-dot-in-perovskite solids are excellent candidates for infrared light-emitting applications. The first generation of dot-in-perovskite light-emitting diodes (LEDs) has shown bright infrared electroluminescence with tunable emission wavelength; however, their performance has been limited by degradation of the active layer at practical operating voltages. This arises from the instability of the three-dimensional (3D) organolead halide perovskite matrix. Herein we report the first dot-in-perovskite solids that employ two-dimensional (2D) perovskites as the matrix. 2D perovskite passivation is achieved via an in situ alkylammonium/alkylamine substitution carried out during the quantum dot (QD) ligand exchange process. This single-step film preparation process enables deposition of the QD/perovskite active layers with thicknesses of 40 nm, over seven times thinner than the first-generation dot-in-perovskite thin films that relied on a multistep synthesis. The dot-in-perovskite film roughness improved from 31 nm for the first-generation films to 3 nm for films as a result of this new approach. The best devices exhibit external quantum efficiency peaks exceeding 2% and radiances of ∼1 W sr–1 m–2, with an improved breakdown voltage up to 7.5 V. Compared to first-generation dot-in-perovskites, this new process reduces materials consumptions 10-fold and represents a promising step toward manufacturable devices.

  12. Quantum Dots in Two-Dimensional Perovskite Matrices for Efficient Near-Infrared Light Emission

    KAUST Repository

    Yang, Zhenyu; Voznyy, Oleksandr; Walters, Grant; Fan, James Z.; Liu, Min; Kinge, Sachin; Hoogland, Sjoerd; Sargent, Edward H.

    2017-01-01

    Quantum-dot-in-perovskite solids are excellent candidates for infrared light-emitting applications. The first generation of dot-in-perovskite light-emitting diodes (LEDs) has shown bright infrared electroluminescence with tunable emission wavelength; however, their performance has been limited by degradation of the active layer at practical operating voltages. This arises from the instability of the three-dimensional (3D) organolead halide perovskite matrix. Herein we report the first dot-in-perovskite solids that employ two-dimensional (2D) perovskites as the matrix. 2D perovskite passivation is achieved via an in situ alkylammonium/alkylamine substitution carried out during the quantum dot (QD) ligand exchange process. This single-step film preparation process enables deposition of the QD/perovskite active layers with thicknesses of 40 nm, over seven times thinner than the first-generation dot-in-perovskite thin films that relied on a multistep synthesis. The dot-in-perovskite film roughness improved from 31 nm for the first-generation films to 3 nm for films as a result of this new approach. The best devices exhibit external quantum efficiency peaks exceeding 2% and radiances of ∼1 W sr–1 m–2, with an improved breakdown voltage up to 7.5 V. Compared to first-generation dot-in-perovskites, this new process reduces materials consumptions 10-fold and represents a promising step toward manufacturable devices.

  13. Analysis of Chuanxiong Rhizoma and its active components by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy.

    Science.gov (United States)

    Guo, Yizhen; Lv, Beiran; Wang, Jingjuan; Liu, Yang; Sun, Suqin; Xiao, Yao; Lu, Lina; Xiang, Li; Yang, Yanfang; Qu, Lei; Meng, Qinghong

    2016-01-15

    As complicated mixture systems, active components of Chuanxiong Rhizoma are very difficult to identify and discriminate. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was applied to study and identify Chuanxiong raw materials and its different segmented production of HPD-100 macroporous resin. Chuanxiong Rhizoma is rich in sucrose. In the FT-IR spectra, water eluate is more similar to sucrose than the powder and the decoction. Their second derivative spectra amplified the differences and revealed the potentially characteristic IR absorption bands and combined with the correlation coefficient, concluding that 50% ethanol eluate had more ligustilide than other eluates. Finally, it can be found from 2DCOS-IR spectra that proteins were extracted by ethanol from Chuanxiong decoction by HPD-100 macroporous resin. It was demonstrated that the above three-step infrared spectroscopy could be applicable for quick, non-destructive and effective analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Discrimination of wild-growing and cultivated Lentinus edodes by tri-step infrared spectroscopy

    Science.gov (United States)

    Lin, Haojian; Liu, Gang; Yang, Weimei; An, Ran; Ou, Quanhong

    2018-01-01

    It's not easy to discriminate dried wild-growing Lentinus edodes (WL) and cultivated Lentinus edodes (CL) by conventional method based on the morphological inspection of fruiting bodies. In this paper, fruiting body samples of WL and CL are discriminated by a tri-step IR spectroscopy method, including Fourier transform infrared (FT-IR) spectroscopy, second derivatives infrared (SD-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy under thermal perturbation. The results show that the FT-IR spectra of WL and CL are similar in holistic spectral profile. More significant differences are exhibited in their SD-IR spectra in the range of 1700 - 900 cm-1. Furthermore, more evident differences have been observed in their synchronous 2D-IR spectra in the range of 2970 - 2900, 1678 - 1390, 1250 -1104 and 1090 - 1030 cm-1. The CL has thirteen auto-peaks at 2958, 2921, 1649, 1563, 1450, 1218, 1192, 1161, 1140, 1110, 1082, 1065 and 1047 cm-1, in which the four strongest auto-peaks are at 2921, 1563, 1192 and 1082 cm-1. The WL shows fifteen auto-peaks at 2960, 2937, 2921, 1650, 1615, 1555, 1458, 1219, 1190, 1138, 1111, 1084, 1068, 1048 and 1033 cm-1, in which the four strongest auto-peaks are at 2921, 1650, 1190 and 1068 cm-1. This study shows the potential of FT-IR spectroscopy and 2D correlation analysis in a simple and quick distinction of wild-growing and cultivated mushrooms.

  15. Dispersive infrared spectroscopy measurements of atmospheric CO2 using a Fabry–Pérot interferometer sensor

    International Nuclear Information System (INIS)

    Chan, K.L.; Ning, Z.; Westerdahl, D.; Wong, K.C.; Sun, Y.W.; Hartl, A.; Wenig, M.O.

    2014-01-01

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO 2 ) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO 2 absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO 2 concentration is determined from the measured optical absorption spectra by fitting it to the CO 2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H 2 O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO 2 measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO 2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO 2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO 2 measurement featuring high accuracy, correction of non-linear absorption and interference of water vapor. - Highlights: • Dispersive infrared

  16. Si-H bond dynamics in hydrogenated amorphous silicon

    Science.gov (United States)

    Scharff, R. Jason; McGrane, Shawn D.

    2007-08-01

    The ultrafast structural dynamics of the Si-H bond in the rigid solvent environment of an amorphous silicon thin film is investigated using two-dimensional infrared four-wave mixing techniques. The two-dimensional infrared (2DIR) vibrational correlation spectrum resolves the homogeneous line shapes ( 4ps waiting times. The Si-H stretching mode anharmonic shift is determined to be 84cm-1 and decreases slightly with vibrational frequency. The 1→2 linewidth increases with vibrational frequency. Frequency dependent vibrational population times measured by transient grating spectroscopy are also reported. The narrow homogeneous line shape, large inhomogeneous broadening, and lack of spectral diffusion reported here present the ideal backdrop for using a 2DIR probe following electronic pumping to measure the transient structural dynamics implicated in the Staebler-Wronski degradation [Appl. Phys. Lett. 31, 292 (1977)] in a-Si:H based solar cells.

  17. Red DirCom

    Directory of Open Access Journals (Sweden)

    Joan Costa

    2007-01-01

    Full Text Available Catorce países congregados de manera activa, a través de una plataforma de encuentro donde se comparten conocimiento y experiencias en la gestión estratégica de la comunicación en las organizaciones. La red reconoce en el DirCom una figura clave del desarrollo corporativo en el nuevo contexto de los negocios, impulsa la exigencia ética a través de la formación y consolida la proyección profesional para posicionar la gestión integral del DirCom en Iberoamérica.

  18. TU-E-BRB-02: DIR QA Options and Research Development

    International Nuclear Information System (INIS)

    Kirby, N.

    2015-01-01

    Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will also discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations

  19. TU-E-BRB-02: DIR QA Options and Research Development

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, N. [University of Texas HSC SA (United States)

    2015-06-15

    Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will also discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations.

  20. Functionalization of liquid-exfoliated two-dimensional 2H-MoS2.

    Science.gov (United States)

    Backes, Claudia; Berner, Nina C; Chen, Xin; Lafargue, Paul; LaPlace, Pierre; Freeley, Mark; Duesberg, Georg S; Coleman, Jonathan N; McDonald, Aidan R

    2015-02-23

    Layered two-dimensional (2D) inorganic transition-metal dichalchogenides (TMDs) have attracted great interest as a result of their potential application in optoelectronics, catalysis, and medicine. However, methods to functionalize and process such 2D TMDs remain scarce. We have established a facile route towards functionalized layered MoS2 . We found that the reaction of liquid-exfoliated 2D MoS2 , with M(OAc)2 salts (M=Ni, Cu, Zn; OAc=acetate) yielded functionalized MoS2 -M(OAc)2 materials. Importantly, this method furnished the 2H-polytype of MoS2 which is a semiconductor. X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT-IR), and thermogravimetric analysis (TGA) provide strong evidence for the coordination of MoS2 surface sulfur atoms to the M(OAc)2 salt. Interestingly, functionalization of 2H-MoS2 allows for its dispersion/processing in more conventional laboratory solvents. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. TU-E-BRB-01: Overview of DIR Advantages/Challenges and Workflow

    International Nuclear Information System (INIS)

    Geneser, S.

    2015-01-01

    Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will also discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations

  2. TU-E-BRB-01: Overview of DIR Advantages/Challenges and Workflow

    Energy Technology Data Exchange (ETDEWEB)

    Geneser, S. [University of California San Francisco (United States)

    2015-06-15

    Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will also discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations.

  3. Dispersive infrared spectroscopy measurements of atmospheric CO{sub 2} using a Fabry–Pérot interferometer sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.L. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Ning, Z., E-mail: zhining@cityu.edu.hk [School of Energy and Environment, City University of Hong Kong (Hong Kong); Guy Carpenter Climate Change Centre, City University of Hong Kong (Hong Kong); Westerdahl, D. [Ability R and D Energy Research Centre, City University of Hong Kong (Hong Kong); Wong, K.C. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Sun, Y.W. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei (China); Hartl, A. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Wenig, M.O. [Meteorological Institute, Ludwig-Maximilians-Universität Munich (Germany)

    2014-02-01

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO{sub 2}) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO{sub 2} absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO{sub 2} concentration is determined from the measured optical absorption spectra by fitting it to the CO{sub 2} reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H{sub 2}O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO{sub 2} measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO{sub 2} measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO{sub 2} analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO{sub 2} measurement featuring high accuracy, correction of non-linear absorption and interference of water

  4. Comprehensive two-dimensional liquid chromatography with on-line Fourier-transform-infrared-spectroscopy detection for the characterization of copolymers

    NARCIS (Netherlands)

    Kok, S.J.; Hankemeier, T.; Schoenmakers, P.J.

    2005-01-01

    The on-line coupling of comprehensive two-dimensional liquid chromatography (liquid chromatography × size-exclusion chromatography, LC × SEC) and infrared (IR) spectroscopy has been realized by means of an IR flow cell. The system has been assessed by the functional-group analysis of a series of

  5. Two-Dimensional Infrared Study of Vibrational Coupling between Azide and Nitrile Reporters in a RNA Nucleoside.

    Science.gov (United States)

    Schmitz, Andrew J; Hogle, David G; Gai, Xin Sonia; Fenlon, Edward E; Brewer, Scott H; Tucker, Matthew J

    2016-09-08

    The vibrations in the azide, N3, asymmetric stretching region and nitrile, CN, symmetric stretching region of 2'-azido-5-cyano-2'-deoxyuridine (N3CNdU) are examined by two-dimensional infrared (2D IR) spectroscopy. At earlier waiting times, the 2D IR spectrum shows the presence of both vibrational transitions along the diagonal and off-diagonal cross peaks indicating vibrational coupling. The coupling strength is determined from the off-diagonal anharmonicity to be 66 cm(-1) for the intramolecular distance of ∼7.9 Å, based on a structural map generated for this model system. In addition, the frequency-frequency correlation decay is detected, monitoring the solvent dynamics around each individual probe position. Overall, these vibrational reporters can be utilized in tandem to simultaneously track global structural information and fast structural fluctuations.

  6. Contact ion pair formation between hard acids and soft bases in aqueous solutions observed with 2DIR spectroscopy.

    Science.gov (United States)

    Sun, Zheng; Zhang, Wenkai; Ji, Minbiao; Hartsock, Robert; Gaffney, Kelly J

    2013-12-12

    The interaction of charged species in aqueous solution has important implications for chemical, biological, and environmental processes. We have used 2DIR spectroscopy to study the equilibrium dynamics of thiocyanate chemical exchange between free ion (NCS(-)) and contact ion pair configurations (MNCS(+)), where M(2+) = Mg(2+) or Ca(2+). Detailed studies of the influence of anion concentration and anion speciation show that the chemical exchange observed with the 2DIR measurements results from NCS(-) exchanging with other anion species in the first solvation shell surrounding Mg(2+) or Ca(2+). The presence of chemical exchange in the 2DIR spectra provides an indirect, but robust, determinant of contact ion pair formation. We observe preferential contact ion pair formation between soft Lewis base anions and hard Lewis acid cations. This observation cannot be easily reconciled with Pearson's acid-base concept or Collins' Law of Matching Water Affinities. The anions that form contact ion pairs also correspond to the ions with an affinity for water and protein surfaces, so similar physical and chemical properties may control these distinct phenomena.

  7. [Study on the identification of six kinds of bee pollens by three-step infrared macro-fingerprint method].

    Science.gov (United States)

    Wu, Jie; Zhou, Quno; Wu, Li-Ming; Au, Jian-Dong; Sun, Su-Qin; Hu, Fu-Liang

    2010-02-01

    Six kinds of bee pollens, including apricot pollen, lotus pollen, rape pollen, camellia pollen, watermelon pollen and corn poppy pollen, were identified non-destructively by Fourier transform infrared spectroscopy (FTIR) combined with derivative spectra and two-dimensional correlation spectroscopy (2D) in the present article. Compared with conventional IR spectra of samples, some certain differences were found in the characteristic peaks of proteins, lipids and carbohydrates. Obvious differences of the six kinds of bee pollens were found in the second derivative spectra. And in the 2D-IR correlation spectra, the samples presented the differences in the position and intensity of the autopeaks and correlation peak clusters. Therefore, the three-step IR macro-fingerprint provides a more rapid and effective method for the identification of different kinds of bee pollens.

  8. Identification of the traditional Tibetan medicine "Shaji" and their different extracts through tri-step infrared spectroscopy

    Science.gov (United States)

    Liu, Yue; Li, Jingyi; Fan, Gang; Sun, Suqin; Zhang, Yuxin; Zhang, Yi; Tu, Ya

    2016-11-01

    Hippophae rhamnoides subsp. sinensis Rousi, Hippophae gyantsensis (Rousi) Y. S. Lian, Hippophae neurocarpa S. W. Liu & T. N. He and Hippophae tibetana Schlechtendal are typically used under one name "Shaji", to treat cardiovascular diseases and lung disorders in Tibetan medicine (TM). A complete set of infrared (IR) macro-fingerprints of these four Hippophae species should be characterized and compared simply, accurately, and in detail for identification. In the present study, tri-step IR spectroscopy, which included Fourier transform IR (FT-IR) spectroscopy, second derivative IR (SD-IR) spectroscopy and two-dimensional correlation IR (2D-IR) spectroscopy, was employed to discriminate the four Hippophae species and their corresponding extracts using different solvents. The relevant spectra exhibited the holistic chemical compositions and variations. Flavonoids, fatty acids and sugars were found to be the main chemical components. Characteristic peak positions, intensities and shapes derived from FT-IR, SD-IR and 2D-IR spectra provided valuable information for sample discrimination. Principal component analysis (PCA) of spectral differences was performed to illustrate the objective identification. Results showed that the species and their extracts can be clearly distinguished. Thus, a quick, precise and effective tri-step IR spectroscopy combined with PCA can be applied to identify and discriminate medicinal materials and their extracts in TM research.

  9. Two Dimensional Symmetric Correlation Functions of the S Operator and Two Dimensional Fourier Transforms: Considering the Line Coupling for P and R Lines of Linear Molecules

    Science.gov (United States)

    Ma, Q.; Boulet, C.; Tipping, R. H.

    2014-01-01

    The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ^S operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

  10. Infrared magneto-spectroscopy of two-dimensional and three-dimensional massless fermions: A comparison

    Energy Technology Data Exchange (ETDEWEB)

    Orlita, M., E-mail: milan.orlita@lncmi.cnrs.fr [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic); Faugeras, C.; Barra, A.-L.; Martinez, G.; Potemski, M. [Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble (France); Basko, D. M. [LPMMC UMR 5493, Université Grenoble 1/CNRS, B.P. 166, 38042 Grenoble (France); Zholudev, M. S. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Gavrilenko, V. I. [Institute for Physics of Microstructures, RAS, Nizhny Novgorod GSP-105 603950 (Russian Federation); Mikhailov, N. N.; Dvoretskii, S. A. [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Neugebauer, P. [Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Berger, C. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Institut Néel/CNRS-UJF BP 166, F-38042 Grenoble Cedex 9 (France); Heer, W. A. de [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-03-21

    Here, we report on a magneto-optical study of two distinct systems hosting massless fermions—two-dimensional graphene and three-dimensional HgCdTe tuned to the zero band gap condition at the point of the semiconductor-to-semimetal topological transition. Both materials exhibit, in the quantum regime, a fairly rich magneto-optical response, which is composed from a series of intra- and interband inter-Landau level resonances with for massless fermions typical √(B) dependence. The impact of the system's dimensionality and of the strength of the spin-orbit interaction on the optical response is also discussed.

  11. The infrared transmission through gold films on ordered two-dimensional non-close-packed colloidal crystals

    International Nuclear Information System (INIS)

    Ju Jing; Zhou Yuqin; Dong Gangqiang

    2014-01-01

    We studied the infrared transmission properties of gold films on ordered two-dimensional non-close-packed polystyrene (PS) colloidal crystal. The gold films consist of gold half-shells on the PS spheres and gold film with 2D arrays of holes on the glass substrate. An extraordinary optical transmission phenomenon could be found in such a structure. Simulations with the finite-difference time-domain method were also employed to get the transmission spectra and electric field distribution. The transmission response of the samples can be adjusted by controlling the thickness of the gold films. Angle-resolved measurements were performed using polarized light to obtain more information about the surface plasmon polariton resonances of the gold films. As the angle changes, the transmission spectra change a lot. The transmission spectra of p-polarized light have quite different properties compared to those of s-polarized light. (semiconductor physics)

  12. DirQ: A Directed Query Dissemination Scheme for Wireless Sensor Networks

    NARCIS (Netherlands)

    Chatterjea, Supriyo; De Luigi, Simone; Havinga, Paul J.M.; Kaminska, B

    This paper describes a Directed Query Dissemination Scheme, DirQ that routes queries to the appropriate source nodes based on both constant and dynamic-valued attributes such as sensor types and sensor values. Location information is not essential for the operation of DirQ. DirQ only uses locally

  13. [Apply fourier transform infrared spectra coupled with two-dimensional correlation analysis to study the evolution of humic acids during composting].

    Science.gov (United States)

    Bu, Gui-jun; Yu, Jing; Di, Hui-hui; Luo, Shi-jia; Zhou, Da-zhai; Xiao, Qiang

    2015-02-01

    The composition and structure of humic acids formed during composting play an important influence on the quality and mature of compost. In order to explore the composition and evolution mechanism, municipal solid wastes were collected to compost and humic and fulvic acids were obtained from these composted municipal solid wastes. Furthermore, fourier transform infrared spectra and two-dimensional correlation analysis were applied to study the composition and transformation of humic and fulvic acids during composting. The results from fourier transform infrared spectra showed that, the composition of humic acids was complex, and several absorbance peaks were observed at 2917-2924, 2844-2852, 2549, 1662, 1622, 1566, 1454, 1398, 1351, 990-1063, 839 and 711 cm(-1). Compared to humic acids, the composition of fulvci acids was simple, and only three peaks were detected at 1725, 1637 and 990 cm(-1). The appearance of these peaks showed that both humic and fulvic acids comprised the benzene originated from lignin and the polysaccharide. In addition, humic acids comprised a large number of aliphatic and protein which were hardly detected in fulvic acids. Aliphatic, polysaccharide, protein and lignin all were degraded during composting, however, the order of degradation was different between humic and fulvci acids. The result from two-dimensional correlation analysis showed that, organic compounds in humic acids were degraded in the following sequence: aliphatic> protein> polysaccharide and lignin, while that in fulvic acids was as following: protein> polysaccharide and aliphatic. A large number of carboxyl, alcohols and ethers were formed during the degradation process, and the carboxyl was transformed into carbonates. It can be concluded that, fourier transform infrared spectra coupled with two-dimensional correlation analysis not only can analyze the function group composition of humic substances, but also can characterize effectively the degradation sequence of these

  14. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Karma Rae [Univ. of California, Berkeley, CA (United States)

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  15. Infrared problems in two-dimensional generalized σ-models

    International Nuclear Information System (INIS)

    Curci, G.; Paffuti, G.

    1989-01-01

    We study the correlations of the energy-momentum tensor for classically conformally invariant generalized σ-models in the Wilson operator-product-expansion approach. We find that these correlations are, in general, infrared divergent. The absence of infrared divergences is obtained, as one can expect, for σ-models on a group manifold or for σ-models with a string-like interpretation. Moreover, the infrared divergences spoil the naive scaling arguments used by Zamolodchikov in the demonstration of the C-theorem. (orig.)

  16. Two-dimensional infrared spectroscopy of vibrational polaritons.

    Science.gov (United States)

    Xiang, Bo; Ribeiro, Raphael F; Dunkelberger, Adam D; Wang, Jiaxi; Li, Yingmin; Simpkins, Blake S; Owrutsky, Jeffrey C; Yuen-Zhou, Joel; Xiong, Wei

    2018-04-19

    We report experimental 2D infrared (2D IR) spectra of coherent light-matter excitations--molecular vibrational polaritons. The application of advanced 2D IR spectroscopy to vibrational polaritons challenges and advances our understanding in both fields. First, the 2D IR spectra of polaritons differ drastically from free uncoupled excitations and a new interpretation is needed. Second, 2D IR uniquely resolves excitation of hybrid light-matter polaritons and unexpected dark states in a state-selective manner, revealing otherwise hidden interactions between them. Moreover, 2D IR signals highlight the impact of molecular anharmonicities which are applicable to virtually all molecular systems. A quantum-mechanical model is developed which incorporates both nuclear and electrical anharmonicities and provides the basis for interpreting this class of 2D IR spectra. This work lays the foundation for investigating phenomena of nonlinear photonics and chemistry of molecular vibrational polaritons which cannot be probed with traditional linear spectroscopy.

  17. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water dimer. II. Infrared spectrum and vibrational dynamics

    DEFF Research Database (Denmark)

    Vendrell, Oriol; Gatti, Fabien; Meyer, Hans-Dieter

    2007-01-01

    The infrared absorption spectrum of the protonated water dimer (H5O2+) is simulated in full dimensionality (15 dimensional) in the spectral range of 0-4000 cm(-1). The calculations are performed using the multiconfiguration time-dependent Hartree (MCTDH) method for propagation of wavepackets. All...

  18. Molecular Characterization, Evolution, and Expression Profiling of the Dirigent (DIR Family Genes in Chinese White Pear (Pyrus bretschneideri

    Directory of Open Access Journals (Sweden)

    Xi Cheng

    2018-04-01

    Full Text Available Stone cells content and size are the key factors determining the internal quality of the pear fruit. Synthesis of lignin and thickening of secondary cell wall are the keys to the development of stone cells. The polymerization of monolignols and secondary cell wall formation requires the participation of dirigent proteins (DIRs. In recent years, DIR family have been studied in higher plants, but lack of comprehensive study in the pear DIR (PbDIR family. This study focuses on the identification and analysis of PbDIR family for the first time. We identified 35 PbDIRs from the pear genome, 89% of which are intronless genes. Phylogenetic tree and chromosome localization analysis showed that 35 PbDIRs were divided into four subfamilies (DIR-a, -b/d, -e, and -g and irregularly distributed among 10 chromosomes. In addition, we identified 29, 26, and 14 DIRs from the other three Rosids (peach, Mei, and grape, respectively. Interspecies microsynteny analysis revealed the collinear gene pairs between pear and peach are the most. Temporal expression analysis showed that the expression changes of seven PbDIRs (DIR-a subfamily: PbDIR4 and PbDIR5; DIR-b/d subfamily: PbDIR11; DIR-g subfamily: PbDIR19; DIR-e subfamily: PbDIR23, 25 and 26 in fruits were consistent with the changes of fruit lignin and stone cells contents. In addition, the subfamily of PbDIRs in fruits showed significant responses after treatment with ABA, SA, and MeJA. According to the protein tertiary structure, key amino acid residues and expression patterns analysis found that PbDIR4 might be involved in the metabolism of lignin and related to stone cells contents in pear fruits. In this study, we systematically analyzed the structure, evolution, function and expression of PbDIR family, which not only confirmed the characteristics of PbDIR family, but also laid the foundation for revealing the role of DIR in pear stone cell development and lignin polymerization.

  19. Orthology Analysis and In Vivo Complementation Studies to Elucidate the Role of DIR1 during Systemic Acquired Resistance in Arabidopsis thaliana and Cucumis sativus

    Directory of Open Access Journals (Sweden)

    Marisa Isaacs

    2016-05-01

    Full Text Available AtDIR1 (Defective in Induced Resistance1 is an acidic lipid transfer protein essential for systemic acquired resistance (SAR in Arabidopsis thaliana. Upon SAR induction, DIR1 moves from locally infected to distant uninfected leaves to activate defense priming; however, a molecular function for DIR1 has not been elucidated. Bioinformatic analysis and in silico homology modeling identified putative AtDIR1 orthologs in crop species, revealing conserved protein motifs within and outside of DIR1’s central hydrophobic cavity. In vitro assays to compare the capacity of recombinant AtDIR1 and targeted AtDIR1-variant proteins to bind the lipophilic probe TNS (6,P-toluidinylnaphthalene-2-sulfonate provided evidence that conserved leucine 43 and aspartic acid 39 contribute to the size of the DIR1 hydrophobic cavity and possibly hydrophobic ligand binding. An Arabidopsis–cucumber SAR model was developed to investigate the conservation of DIR1 function in cucumber (Cucumis sativus, and we demonstrated that phloem exudates from SAR-induced cucumber rescued the SAR defect in the Arabidopsis dir1-1 mutant. Additionally, an AtDIR1 antibody detected a protein of the same size as AtDIR1 in SAR-induced cucumber phloem exudates, providing evidence that DIR1 function during SAR is conserved in Arabidopsis and cucumber. In vitro TNS displacement assays demonstrated that recombinant AtDIR1 did not bind the SAR signals azelaic acid (AzA, glycerol-3-phosphate or pipecolic acid. However, recombinant CsDIR1 and CsDIR2 interacted weakly with AzA and pipecolic acid. Bioinformatic and functional analyses using the Arabidopsis–cucumber SAR model provide evidence that DIR1 orthologs exist in tobacco, tomato, cucumber, and soybean, and that DIR1-mediated SAR signaling is conserved in Arabidopsis and cucumber.

  20. Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Tokihiro; Loo, Billy W Jr; Keall, Paul J [Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Dr, Stanford, CA 94305-5847 (United States); Kabus, Sven; Lorenz, Cristian; Von Berg, Jens; Blaffert, Thomas [Department of Digital Imaging, Philips Research Europe, Roentgenstrasse 24-26, D-22335 Hamburg (Germany); Klinder, Tobias, E-mail: Tokihiro@stanford.edu [Clinical Informatics, Interventional, and Translational Solutions, Philips Research North America, Briarcliff Manor, NY 10510 (United States)

    2011-04-07

    A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIR{sup sur}) and volumetric (DIR{sup vol}), and two metrics: Hounsfield unit (HU) change (V{sub HU}) and Jacobian determinant of deformation (V{sub Jac}), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. V{sub HU} resulted in statistically significant differences for both DIR{sup sur} (0.14 {+-} 0.14 versus 0.29 {+-} 0.16, p = 0.01) and DIR{sup vol} (0.13 {+-} 0.13 versus 0.27 {+-} 0.15, p < 0.01). However, V{sub Jac} resulted in non-significant differences for both DIR{sup sur} (0.15 {+-} 0.07 versus 0.17 {+-} 0.08, p = 0.20) and DIR{sup vol} (0.17 {+-} 0.08 versus 0.19 {+-} 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A

  1. Dimensionality Crossover in the Organic Superconductor Tetramethyltetraselenafulvalene Hexafluorophosphate [(TMTSF)2PF6

    DEFF Research Database (Denmark)

    Jacobsen, Claus Schelde; Tanner, D. B.; Bechgaard, K.

    1981-01-01

    Polarized reflectance measurements from the far infrared to the visible are reported for (TMTSF)2PF6. At low temperatures, both parallel and perpendicular polarizations show plasma edges in the infrared with metallic reflection below these edges, indicating two- or three-dimensional behavior. The...

  2. Photon-phonon-enhanced infrared rectification in a two-dimensional nanoantenna-coupled tunnel diode

    International Nuclear Information System (INIS)

    Kadlec, Emil A.; Jarecki, Robert L.; Starbuck, Andrew; Peters, David W.; Davids, Paul S.

    2016-01-01

    The interplay of strong infrared photon-phonon coupling with electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast photon-assisted tunneling in metal-oxide-semiconductor (MOS) structures. Infrared active optical phonon modes in polar oxides lead to strong dispersion and enhanced electric fields at material interfaces. We find that the infrared dispersion of SiO_2 near a longitudinal optical phonon mode can effectively impedance match a photonic surface mode into a nanoscale tunnel gap that results in large transverse-field confinement. An integrated 2D nanoantenna structure on a distributed large-area MOS tunnel-diode rectifier is designed and built to resonantly excite infrared surface modes and is shown to efficiently channel infrared radiation into nanometer-scale gaps in these MOS devices. This enhanced-gap transverse-electric field is converted to a rectified tunneling displacement current resulting in a dc photocurrent. We examine the angular and polarization-dependent spectral photocurrent response of these 2D nanoantenna-coupled tunnel diodes in the photon-enhanced tunneling spectral region. Lastly, our 2D nanoantenna-coupled infrared tunnel-diode rectifier promises to impact large-area thermal energy harvesting and infrared direct detectors.

  3. Facile synthesis of CuSe nanoparticles and high-quality single-crystal two-dimensional hexagonal nanoplatelets with tunable near-infrared optical absorption

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yimin [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Korolkov, Ilia [Laboratory of Glasses and Ceramics, Institute of Chemistry, CNRS-Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex (France); Qiao, Xvsheng [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Xianghua [Laboratory of Glasses and Ceramics, Institute of Chemistry, CNRS-Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex (France); Wan, Jun; Fan, Xianping [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-06-15

    A rapid injection approach is used to synthesize the copper selenide nanoparticles and two-dimensional single crystal nanoplates. This technique excludes the use of toxic or expensive materials, increasing the availability of two-dimensional binary chalcogenide semiconductors. The structure of the nanocrystals has been studied and the possible formation mechanism of the nanoplates has been proposed. The optical absorption showed that the nanoplates demonstrated wide and tuneable absorption band in the visible and near infrared region. These nanoplates could be interesting for converting solar energy and for nanophotonic devices operating in the near infrared. - Graphical abstract: TEM images of the copper selenides nanoparticles and nanoplates synthesized at 180 °C for 0 min, 10 min, 60 min. And the growth mechanism of the copper selenide nanoplates via the “oriented attachment”. Display Omitted - Highlights: • CuSe nanoparticles and nanoplates are synthesized by a rapid injection approach. • CuSe band gap can be widely tuned simply by modifying the synthesized time. • Al{sup 3+} ions have a significant impact on the growth rate of the nanoplates. • Growth mechanism of the CuSe nanoplates is based on the “oriented attachment”.

  4. On the relation between Marcus theory and ultrafast spectroscopy of solvation kinetics

    Science.gov (United States)

    Roy, Santanu; Galib, Mirza; Schenter, Gregory K.; Mundy, Christopher J.

    2018-01-01

    The phenomena of solvent exchange control the process of solvating ions, protons, and charged molecules. Building upon our extension of Marcus' philosophy of electron transfer, we provide a new perspective of ultrafast solvent exchange mechanism around ions measurable by two-dimensional infrared (2DIR) spectroscopy. In this theory, solvent rearrangement drives an ion-bound water to an activated state of higher coordination number, triggering ion-water separation that leads to the solvent-bound state of the water molecule. This ion-bound to solvent-bound transition rate for a BF4--water system is computed using ab initio molecular dynamics and Marcus theory, and is found to be in excellent agreement with the 2DIR measurement.

  5. Raman Scattering from Higgs Mode Oscillations in the Two-Dimensional Antiferromagnet Ca_{2}RuO_{4}.

    Science.gov (United States)

    Souliou, Sofia-Michaela; Chaloupka, Jiří; Khaliullin, Giniyat; Ryu, Gihun; Jain, Anil; Kim, B J; Le Tacon, Matthieu; Keimer, Bernhard

    2017-08-11

    We present and analyze Raman spectra of the Mott insulator Ca_{2}RuO_{4}, whose quasi-two-dimensional antiferromagnetic order has been described as a condensate of low-lying spin-orbit excitons with angular momentum J_{eff}=1. In the A_{g} polarization geometry, the amplitude (Higgs) mode of the spin-orbit condensate is directly probed in the scalar channel, thus avoiding infrared-singular magnon contributions. In the B_{1g} geometry, we observe a single-magnon peak as well as two-magnon and two-Higgs excitations. Model calculations using exact diagonalization quantitatively agree with the observations. Together with recent neutron scattering data, our study provides strong evidence for excitonic magnetism in Ca_{2}RuO_{4} and points out new perspectives for research on the Higgs mode in two dimensions.

  6. Postmortem verification of MS cortical lesion detection with 3D DIR

    NARCIS (Netherlands)

    Seewann, A.M.; Kooi, E.J.; Roosendaal, S.D.; Pouwels, P.J.W.; Wattjes, M.P.; van der Valk, P.; Barkhof, F.; Polman, C.H.; Geurts, J.J.G.

    2012-01-01

    Objective: To assess the sensitivity and specificity of 3D double inversion recovery (DIR) MRI for detecting multiple sclerosis (MS) cortical lesions (CLs) using a direct postmortem MRI to histopathology comparison. Methods: Single-slab 3D DIR and 3D fluid-attenuated inversion recovery (FLAIR)

  7. Topology as fluid geometry two-dimensional spaces, volume 2

    CERN Document Server

    Cannon, James W

    2017-01-01

    This is the second of a three volume collection devoted to the geometry, topology, and curvature of 2-dimensional spaces. The collection provides a guided tour through a wide range of topics by one of the twentieth century's masters of geometric topology. The books are accessible to college and graduate students and provide perspective and insight to mathematicians at all levels who are interested in geometry and topology. The second volume deals with the topology of 2-dimensional spaces. The attempts encountered in Volume 1 to understand length and area in the plane lead to examples most easily described by the methods of topology (fluid geometry): finite curves of infinite length, 1-dimensional curves of positive area, space-filling curves (Peano curves), 0-dimensional subsets of the plane through which no straight path can pass (Cantor sets), etc. Volume 2 describes such sets. All of the standard topological results about 2-dimensional spaces are then proved, such as the Fundamental Theorem of Algebra (two...

  8. A Flow System for Generation of Concentration Perturbation in Two-Dimensional Correlation Near-Infrared Spectroscopy: Application to Variable Selection in Multivariate Calibration

    OpenAIRE

    Pereira, CF; Pasquini, C

    2010-01-01

    A flow system is proposed to produce a concentration perturbation in liquid samples, aiming at the generation of two-dimensional correlation near-infrared spectra. The system presents advantages in relation to batch systems employed for the same purpose: the experiments are accomplished in a closed system; application of perturbation is rapid and easy; and the experiments can be carried out with micro-scale volumes. The perturbation system has been evaluated in the investigation and selection...

  9. Two-dimensional temperature and carbon dioxide concentration profiles in atmospheric laminar diffusion flames measured by mid-infrared direct absorption spectroscopy at 4.2 μm

    Science.gov (United States)

    Liu, Xunchen; Zhang, Guoyong; Huang, Yan; Wang, Yizun; Qi, Fei

    2018-04-01

    We present a multi-line flame thermometry technique based on mid-infrared direct absorption spectroscopy of carbon dioxide at its v_3 fundamental around 4.2 μm that is particularly suitable for sooting flames. Temperature and concentration profiles of gas phase molecules in a flame are important characteristics to understand its flame structure and combustion chemistry. One of the standard laboratory flames to analyze polycyclic aromatic hydrocarbons (PAH) and soot formation is laminar non-premixed co-flow flame, but PAH and soot introduce artifact to most non-contact optical measurements. Here we report an accurate diagnostic method of the temperature and concentration profiles of CO2 in ethylene diffusion flames by measuring its v_3 vibrational fundamental. An interband cascade laser was used to probe the R-branch bandhead at 4.2 μm, which is highly sensitive to temperature change, free from soot interference and ambient background. Calibration measurement was carried out both in a low-pressure Herriott cell and an atmospheric pressure tube furnace up to 1550 K to obtain spectroscopic parameters for high-temperature spectra. In our co-flow flame measurement, two-dimensional line-of-sight optical depth of an ethylene/N2 laminar sooting flame was recorded by dual-beam absorption scheme. The axially symmetrical attenuation coefficient profile of CO2 in the co-flow flame was reconstructed from the optical depth by Abel inversion. Spatially resolved flame temperature and in situ CO2 volume fraction profiles were derived from the calibrated CO2 spectroscopic parameters and compared with temperature profiles measured by two-line atomic fluorescence.

  10. Energy Spectra of Vortex Distributions in Two-Dimensional Quantum Turbulence

    Directory of Open Access Journals (Sweden)

    Ashton S. Bradley

    2012-10-01

    Full Text Available We theoretically explore key concepts of two-dimensional turbulence in a homogeneous compressible superfluid described by a dissipative two-dimensional Gross-Pitaeveskii equation. Such a fluid supports quantized vortices that have a size characterized by the healing length ξ. We show that, for the divergence-free portion of the superfluid velocity field, the kinetic-energy spectrum over wave number k may be decomposed into an ultraviolet regime (k≫ξ^{-1} having a universal k^{-3} scaling arising from the vortex core structure, and an infrared regime (k≪ξ^{-1} with a spectrum that arises purely from the configuration of the vortices. The Novikov power-law distribution of intervortex distances with exponent -1/3 for vortices of the same sign of circulation leads to an infrared kinetic-energy spectrum with a Kolmogorov k^{-5/3} power law, which is consistent with the existence of an inertial range. The presence of these k^{-3} and k^{-5/3} power laws, together with the constraint of continuity at the smallest configurational scale k≈ξ^{-1}, allows us to derive a new analytical expression for the Kolmogorov constant that we test against a numerical simulation of a forced homogeneous, compressible, two-dimensional superfluid. The numerical simulation corroborates our analysis of the spectral features of the kinetic-energy distribution, once we introduce the concept of a clustered fraction consisting of the fraction of vortices that have the same sign of circulation as their nearest neighboring vortices. Our analysis presents a new approach to understanding two-dimensional quantum turbulence and interpreting similarities and differences with classical two-dimensional turbulence, and suggests new methods to characterize vortex turbulence in two-dimensional quantum fluids via vortex position and circulation measurements.

  11. Two-dimensional N = 2 Super-Yang-Mills Theory

    Science.gov (United States)

    August, Daniel; Wellegehausen, Björn; Wipf, Andreas

    2018-03-01

    Supersymmetry is one of the possible scenarios for physics beyond the standard model. The building blocks of this scenario are supersymmetric gauge theories. In our work we study the N = 1 Super-Yang-Mills (SYM) theory with gauge group SU(2) dimensionally reduced to two-dimensional N = 2 SYM theory. In our lattice formulation we break supersymmetry and chiral symmetry explicitly while preserving R symmetry. By fine tuning the bar-mass of the fermions in the Lagrangian we construct a supersymmetric continuum theory. To this aim we carefully investigate mass spectra and Ward identities, which both show a clear signal of supersymmetry restoration in the continuum limit.

  12. Performance of 12 DIR algorithms in low-contrast regions for mass and density conserving deformation

    International Nuclear Information System (INIS)

    Yeo, U. J.; Supple, J. R.; Franich, R. D.; Taylor, M. L.; Smith, R.; Kron, T.

    2013-01-01

    Purpose: Deformable image registration (DIR) has become a key tool for adaptive radiotherapy to account for inter- and intrafraction organ deformation. Of contemporary interest, the application to deformable dose accumulation requires accurate deformation even in low contrast regions where dose gradients may exist within near-uniform tissues. One expects high-contrast features to generally be deformed more accurately by DIR algorithms. The authors systematically assess the accuracy of 12 DIR algorithms and quantitatively examine, in particular, low-contrast regions, where accuracy has not previously been established.Methods: This work investigates DIR algorithms in three dimensions using deformable gel (DEFGEL) [U. J. Yeo, M. L. Taylor, L. Dunn, R. L. Smith, T. Kron, and R. D. Franich, “A novel methodology for 3D deformable dosimetry,” Med. Phys. 39, 2203–2213 (2012)], for application to mass- and density-conserving deformations. CT images of DEFGEL phantoms with 16 fiducial markers (FMs) implanted were acquired in deformed and undeformed states for three different representative deformation geometries. Nonrigid image registration was performed using 12 common algorithms in the public domain. The optimum parameter setup was identified for each algorithm and each was tested for deformation accuracy in three scenarios: (I) original images of the DEFGEL with 16 FMs; (II) images with eight of the FMs mathematically erased; and (III) images with all FMs mathematically erased. The deformation vector fields obtained for scenarios II and III were then applied to the original images containing all 16 FMs. The locations of the FMs estimated by the algorithms were compared to actual locations determined by CT imaging. The accuracy of the algorithms was assessed by evaluation of three-dimensional vectors between true marker locations and predicted marker locations.Results: The mean magnitude of 16 error vectors per sample ranged from 0.3 to 3.7, 1.0 to 6.3, and 1.3 to 7

  13. Infrared realization of dS2 in AdS2

    Science.gov (United States)

    Anninos, Dionysios; Hofman, Diego M.

    2018-04-01

    We describe a two-dimensional geometry that smoothly interpolates between an asymptotically AdS2 geometry and the static patch of dS2. We find this ‘centaur’ geometry to be a solution of dilaton gravity with a specific class of potentials for the dilaton. We interpret the centaur geometry as a thermal state in the putative quantum mechanics dual to the AdS2 evolved with the global Hamiltonian. We compute the thermodynamic properties and observe that the centaur state has finite entropy and positive specific heat. The static patch is the infrared part of the centaur geometry. We discuss boundary observables sensitive to the static patch region.

  14. Two-dimensional NMR spectrometry

    International Nuclear Information System (INIS)

    Farrar, T.C.

    1987-01-01

    This article is the second in a two-part series. In part one (ANALYTICAL CHEMISTRY, May 15) the authors discussed one-dimensional nuclear magnetic resonance (NMR) spectra and some relatively advanced nuclear spin gymnastics experiments that provide a capability for selective sensitivity enhancements. In this article and overview and some applications of two-dimensional NMR experiments are presented. These powerful experiments are important complements to the one-dimensional experiments. As in the more sophisticated one-dimensional experiments, the two-dimensional experiments involve three distinct time periods: a preparation period, t 0 ; an evolution period, t 1 ; and a detection period, t 2

  15. Polarization-selective transmission in stacked two-dimensional complementary plasmonic crystal slabs

    Science.gov (United States)

    Iwanaga, Masanobu

    2010-02-01

    It has been experimentally and numerically shown that transmission at near infrared wavelengths is selectively controlled by polarizations in two-dimensional complementary plasmonic crystal slabs (2D c-PlCSs) of stacked unit cell. This feature is naturally derived by taking account of Babinet's principle. Moreover, the slight structural modification of the unit cell has been found to result in a drastic change in linear optical responses of stacked 2D c-PlCSs. These results substantiate the feasibility of 2D c-PlCSs for producing efficient polarizers with subwavelength thickness.

  16. DIRS1-like retrotransposons are widely distributed among Decapoda and are particularly present in hydrothermal vent organisms

    Directory of Open Access Journals (Sweden)

    Bonnivard Eric

    2009-04-01

    Full Text Available Abstract Background Transposable elements are major constituents of eukaryote genomes and have a great impact on genome structure and stability. Considering their mutational abilities, TEs can contribute to the genetic diversity and evolution of organisms. Knowledge of their distribution among several genomes is an essential condition to study their dynamics and to better understand their role in species evolution. DIRS1-like retrotransposons are a particular group of retrotransposons according to their mode of transposition that implies a tyrosine recombinase. To date, they have been described in a restricted number of species in comparison with the LTR retrotransposons. In this paper, we determine the distribution of DIRS1-like elements among 25 decapod species, 10 of them living in hydrothermal vents that correspond to particularly unstable environments. Results Using PCR approaches, we have identified 15 new DIRS1-like families in 15 diverse decapod species (shrimps, lobsters, crabs and galatheid crabs. Hydrothermal organisms show a particularly great diversity of DIRS1-like elements with 5 families characterized among Alvinocarididae shrimps and 3 in the galatheid crab Munidopsis recta. Phylogenic analyses show that these elements are divergent toward the DIRS1-like families previously described in other crustaceans and arthropods and form a new clade called AlDIRS1. At larger scale, the distribution of DIRS1-like retrotransposons appears more or less patchy depending on the taxa considered. Indeed, a scattered distribution can be observed in the infraorder Brachyura whereas all the species tested in infraorders Caridea and Astacidea harbor some DIRS1-like elements. Conclusion Our results lead to nearly double both the number of DIRS1-like elements described to date, and the number of species known to harbor these ones. In this study, we provide the first degenerate primers designed to look specifically for DIRS1-like retrotransposons. They

  17. Linear and non-linear infrared response of one-dimensional vibrational Holstein polarons in the anti-adiabatic limit: Optical and acoustical phonon models

    Science.gov (United States)

    Falvo, Cyril

    2018-02-01

    The theory of linear and non-linear infrared response of vibrational Holstein polarons in one-dimensional lattices is presented in order to identify the spectral signatures of self-trapping phenomena. Using a canonical transformation, the optical response is computed from the small polaron point of view which is valid in the anti-adiabatic limit. Two types of phonon baths are considered: optical phonons and acoustical phonons, and simple expressions are derived for the infrared response. It is shown that for the case of optical phonons, the linear response can directly probe the polaron density of states. The model is used to interpret the experimental spectrum of crystalline acetanilide in the C=O range. For the case of acoustical phonons, it is shown that two bound states can be observed in the two-dimensional infrared spectrum at low temperature. At high temperature, analysis of the time-dependence of the two-dimensional infrared spectrum indicates that bath mediated correlations slow down spectral diffusion. The model is used to interpret the experimental linear-spectroscopy of model α-helix and β-sheet polypeptides. This work shows that the Davydov Hamiltonian cannot explain the observations in the NH stretching range.

  18. Effect of Different Heat Treatment Temperatures on the Chemical Composition and Structure of Chinese Fir Wood

    Directory of Open Access Journals (Sweden)

    Shichao Cheng

    2016-03-01

    Full Text Available The properties of wood can be improved after heat-treatment. There have been many studies dealing with mechanical properties and chemical modifications of heat-treated wood. The purpose of this paper is to provide a new analysis method, to give better insights on the hemicelluloses, cellulose, and lignin contents of heat-treated wood by using Fourier transform infrared (FT-IR and two-dimensional infrared (2D-IR spectroscopies. The FT-IR spectra results showed progressive degradation in the carbonyl groups of the glucuronic acid units and degradation of the pyranose of hemicelluloses. These changes were measured as the percentage decrease of crystalline cellulose and the loss of C=O and C=C groups linking together the aromatic skeleton of lignin. The 2D-IR spectra showed the appearance of 5 × 5 peak clusters in the 1000 to 1200 cm-1 region, which could account for the hemicellulose degradation. In addition, changes in the degree of sensitivity at 1627 and 1509 cm-1 coincided with cross-linking reactions among the aromatic units in the lignin molecules.

  19. A Novel Soybean Dirigent Gene GmDIR22 Contributes to Promotion of Lignan Biosynthesis and Enhances Resistance to Phytophthora sojae

    Directory of Open Access Journals (Sweden)

    Ninghui Li

    2017-07-01

    Full Text Available Phytophthora root and stem rot caused by the oomycete pathogen Phytophthora sojae is a destructive disease of soybean worldwide. Plant dirigent proteins (DIR are proposed to have roles in biosynthesis of either lignan or lignin-like molecules, and are important for defense responses, secondary metabolism, and pathogen resistance. In the present work, a novel DIR gene expressed sequence tag is identified as up-regulated in the highly resistant soybean cultivar ‘Suinong 10’ inoculated with P. sojae. The full length cDNA is isolated using rapid amplification of cDNA ends, and designated GmDIR22 (GenBank accession no. HQ_993047. The full length GmDIR22 is 789 bp and contains a 567 bp open reading frame encoding a polypeptide of 188 amino acids. The sequence analysis indicated that GmDIR22 contains a conserved dirigent domain at amino acid residues 43–187. The quantitative real-time reverse transcription PCR demonstrated that soybean GmDIR22 mRNA is expressed most highly in stems, followed by roots and leaves. The treatments with stresses demonstrated that GmDIR22 is significantly induced by P. sojae and gibberellic acid (GA3, and also responds to salicylic acid, methyl jasmonic acid, and abscisic acid. The GmDIR22 is targeted to the cytomembrane when transiently expressed in Arabidopsis protoplasts. Moreover, The GmDIR22 recombinant protein purified from Escherichia coli could effectively direct E-coniferyl alcohol coupling into lignan (+-pinoresinol. Accordingly, the overexpression of GmDIR22 in transgenic soybean increased total lignan accumulation. Moreover, the lignan extracts from GmDIR22 transgenic plants effectively inhibits P. sojae hyphal growth. Furthermore, the transgenic overexpression of GmDIR22 in the susceptible soybean cultivar ‘Dongnong 50’ enhances its resistance to P. sojae. Collectively, these data suggested that the primary role of GmDIR22 is probably involved in the regulation of lignan biosynthesis, and which

  20. SU(1,2) invariance in two-dimensional oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Krivonos, Sergey [Bogoliubov Laboratory of Theoretical Physics,Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nersessian, Armen [Yerevan State University,1 Alex Manoogian St., Yerevan, 0025 (Armenia); Tomsk Polytechnic University,Lenin Ave. 30, 634050 Tomsk (Russian Federation)

    2017-02-01

    Performing the Hamiltonian analysis we explicitly established the canonical equivalence of the deformed oscillator, constructed in arXiv:1607.03756, with the ordinary one. As an immediate consequence, we proved that the SU(1,2) symmetry is the dynamical symmetry of the ordinary two-dimensional oscillator. The characteristic feature of this SU(1,2) symmetry is a non-polynomial structure of its generators written in terms of the oscillator variables.

  1. Optical coupling between atomically thin black phosphorus and a two dimensional photonic crystal nanocavity

    Science.gov (United States)

    Ota, Yasutomo; Moriya, Rai; Yabuki, Naoto; Arai, Miho; Kakuda, Masahiro; Iwamoto, Satoshi; Machida, Tomoki; Arakawa, Yasuhiko

    2017-05-01

    Atomically thin black phosphorus (BP) is an emerging two dimensional (2D) material exhibiting bright photoluminescence in the near infrared region. Coupling its radiation to photonic nanostructures will be an important step toward the realization of 2D material based nanophotonic devices that operate efficiently in the near infrared region, which includes the technologically important optical telecommunication wavelength bands. In this letter, we demonstrate the optical coupling between atomically thin BP and a 2D photonic crystal nanocavity. We employed a home-build dry transfer apparatus for placing a thin BP flake on the surface of the nanocavity. Their optical coupling was analyzed through measuring cavity mode emission under optical carrier injection at room temperature.

  2. Effects on the Thermo-Mechanical and Crystallinity Properties of Nylon 6,6 Electrospun Fibres Reinforced with One Dimensional (1D and Two Dimensional (2D Carbon

    Directory of Open Access Journals (Sweden)

    Francisco Medellín-Rodríguez

    2013-08-01

    Full Text Available Electrospun one dimensional (1D and two dimensional (2D carbon based polymer nanocomposites are studied in order to determine the effect provided by the two differently structured nanofillers on crystallinity and thermo-mechanical properties of the nanofibres. The nanomaterials studied are pristine carbon nanotubes, oxidised carbon nanotubes, reduced graphene oxide and graphene oxide. Functional groups associated with the order structure of the polymers are analysed by infrared and Raman spectroscopies; the morphology is studied by scanning electron microscopy and the crystallinity properties are investigated by differential scanning calorimetry and X-ray diffraction. Differences in crystallisation behaviour between 1D and 2D carbon based nanofibres are shown by their crystallinity degree and their crystal sizes. The nanocomposite crystal sizes perpendicular to the plane (100 decrease with nanofiller content in all cases. The crystallinity trend and crystal sizes are in accordance with storage modulus response. The results also suggest that functionalisation favours interfacial bonding and dispersion of the nanomaterials within the polymer matrix. As a consequence the number of nucleating sites increases which in turn decreases the crystal size in the nanocomposites. These features explain the improved thermo-mechanical properties in the nanocomposites.

  3. Equivalence of two-dimensional gravities

    International Nuclear Information System (INIS)

    Mohammedi, N.

    1990-01-01

    The authors find the relationship between the Jackiw-Teitelboim model of two-dimensional gravity and the SL(2,R) induced gravity. These are shown to be related to a two-dimensional gauge theory obtained by dimensionally reducing the Chern-Simons action of the 2 + 1 dimensional gravity. The authors present an explicit solution to the equations of motion of the auxiliary field of the Jackiw-Teitelboim model in the light-cone gauge. A renormalization of the cosmological constant is also given

  4. Conservation laws for two (2 + 1)-dimensional differential-difference systems

    International Nuclear Information System (INIS)

    Yu Guofu; Tam, H.-W.

    2006-01-01

    Two integrable differential-difference equations are considered. One is derived from the discrete BKP equation and the other is a symmetric (2 + 1)-dimensional Lotka-Volterra equation. An infinite number of conservation laws for the two differential-difference equations are deduced

  5. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

    International Nuclear Information System (INIS)

    Mandal, Aritra; Tokmakoff, Andrei

    2015-01-01

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm −1 . We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions

  6. Two-dimensional multifractal cross-correlation analysis

    International Nuclear Information System (INIS)

    Xi, Caiping; Zhang, Shuning; Xiong, Gang; Zhao, Huichang; Yang, Yonghong

    2017-01-01

    Highlights: • We study the mathematical models of 2D-MFXPF, 2D-MFXDFA and 2D-MFXDMA. • Present the definition of the two-dimensional N 2 -partitioned multiplicative cascading process. • Do the comparative analysis of 2D-MC by 2D-MFXPF, 2D-MFXDFA and 2D-MFXDMA. • Provide a reference on the choice and parameter settings of these methods in practice. - Abstract: There are a number of situations in which several signals are simultaneously recorded in complex systems, which exhibit long-term power-law cross-correlations. This paper presents two-dimensional multifractal cross-correlation analysis based on the partition function (2D-MFXPF), two-dimensional multifractal cross-correlation analysis based on the detrended fluctuation analysis (2D-MFXDFA) and two-dimensional multifractal cross-correlation analysis based on the detrended moving average analysis (2D-MFXDMA). We apply these methods to pairs of two-dimensional multiplicative cascades (2D-MC) to do a comparative study. Then, we apply the two-dimensional multifractal cross-correlation analysis based on the detrended fluctuation analysis (2D-MFXDFA) to real images and unveil intriguing multifractality in the cross correlations of the material structures. At last, we give the main conclusions and provide a valuable reference on how to choose the multifractal algorithms in the potential applications in the field of SAR image classification and detection.

  7. Is 3D MPRAGE better than the combination DIR/PSIR for cortical lesion detection at 3T MRI?

    Science.gov (United States)

    Nelson, Flavia; Poonawalla, Aziz; Datta, Sushmita; Wolinsky, Jerry; Narayana, Ponnada

    2014-03-01

    Based on the application of newer magnetic resonance imaging (MRI) acquisition sequences, the detection of cortical lesions (CL) in multiple sclerosis (MS) has significantly improved. Double inversion recovery (DIR) at 3T has increased the detection sensitivity and classification specificity when combined with phase sensitive inversion recovery (PSIR). Previous findings with 3D magnetization prepared rapid acquisition with gradient echo (MPRAGE) sequences, showed improved classification specificity of purely intracortical (IC) and mixed (MX) lesions, compared to the classification based on DIR/PSIR. Direct comparison between the detection of CL by 3D MPRAGE and by DIR/PSIR at 3T has not been evaluated. Eleven subjects were imaged on a 3T magnet. DIR/PSIR and 3D MPRAGE images were reviewed independently. Each image set was reviewed twice; only lesions detected on both sessions were scored. Review time per scan was ~5min for DIR/PSIR and ~15min for 3D MPRAGE. We identified 141 CL (62 IC+79 MX) based on DIR/PSIR images vs. 93 (38 IC+55 MX) based on MPRAGE from all eleven patients. MPRAGE under-detected the number of CL in seven cases and over-detected the number of CL in three, only one case had the same number of CL on both sets of images. Combination DIR/PSIR at 3T is superior to 3D MPRAGE for detection of cortical gray matter lesions in MS. The contrast-to-noise ratio of CL appears to be inferior on the MPRAGE images relative to DIR/PSIR. © 2013 Published by Elsevier B.V.

  8. Application of Tandem Two-Dimensional Mass Spectrometry for Top-Down Deep Sequencing of Calmodulin.

    Science.gov (United States)

    Floris, Federico; Chiron, Lionel; Lynch, Alice M; Barrow, Mark P; Delsuc, Marc-André; O'Connor, Peter B

    2018-06-04

    Two-dimensional mass spectrometry (2DMS) involves simultaneous acquisition of the fragmentation patterns of all the analytes in a mixture by correlating their precursor and fragment ions by modulating precursor ions systematically through a fragmentation zone. Tandem two-dimensional mass spectrometry (MS/2DMS) unites the ultra-high accuracy of Fourier transform ion cyclotron resonance (FT-ICR) MS/MS and the simultaneous data-independent fragmentation of 2DMS to achieve extensive inter-residue fragmentation of entire proteins. 2DMS was recently developed for top-down proteomics (TDP), and applied to the analysis of calmodulin (CaM), reporting a cleavage coverage of about ~23% using infrared multiphoton dissociation (IRMPD) as fragmentation technique. The goal of this work is to expand the utility of top-down protein analysis using MS/2DMS in order to extend the cleavage coverage in top-down proteomics further into the interior regions of the protein. In this case, using MS/2DMS, the cleavage coverage of CaM increased from ~23% to ~42%. Graphical Abstract Two-dimensional mass spectrometry, when applied to primary fragment ions from the source, allows deep-sequencing of the protein calmodulin.

  9. Two-dimensional fluorescence lifetime correlation spectroscopy. 2. Application.

    Science.gov (United States)

    Ishii, Kunihiko; Tahara, Tahei

    2013-10-03

    In the preceding article, we introduced the theoretical framework of two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS). In this article, we report the experimental implementation of 2D FLCS. In this method, two-dimensional emission-delay correlation maps are constructed from the photon data obtained with the time-correlated single photon counting (TCSPC), and then they are converted to 2D lifetime correlation maps by the inverse Laplace transform. We develop a numerical method to realize reliable transformation, employing the maximum entropy method (MEM). We apply the developed actual 2D FLCS to two real systems, a dye mixture and a DNA hairpin. For the dye mixture, we show that 2D FLCS is experimentally feasible and that it can identify different species in an inhomogeneous sample without any prior knowledge. The application to the DNA hairpin demonstrates that 2D FLCS can disclose microsecond spontaneous dynamics of biological molecules in a visually comprehensible manner, through identifying species as unique lifetime distributions. A FRET pair is attached to the both ends of the DNA hairpin, and the different structures of the DNA hairpin are distinguished as different fluorescence lifetimes in 2D FLCS. By constructing the 2D correlation maps of the fluorescence lifetime of the FRET donor, the equilibrium dynamics between the open and the closed forms of the DNA hairpin is clearly observed as the appearance of the cross peaks between the corresponding fluorescence lifetimes. This equilibrium dynamics of the DNA hairpin is clearly separated from the acceptor-missing DNA that appears as an isolated diagonal peak in the 2D maps. The present study clearly shows that newly developed 2D FLCS can disclose spontaneous structural dynamics of biological molecules with microsecond time resolution.

  10. Two-dimensional spectroscopy at infrared and optical frequencies

    OpenAIRE

    Hochstrasser, Robin M.

    2007-01-01

    This Perspective on multidimensional spectroscopy in the optical and infrared spectral regions focuses on the principles and the scientific and technical challenges facing these new fields. The methods hold great promise for advances in the visualization of time-dependent structural changes in complex systems ranging from liquids to biological assemblies, new materials, and fundamental physical processes. The papers in this special feature on multidimensional spectroscopy in chemistry, physic...

  11. Development of plenoptic infrared camera using low dimensional material based photodetectors

    Science.gov (United States)

    Chen, Liangliang

    Infrared (IR) sensor has extended imaging from submicron visible spectrum to tens of microns wavelength, which has been widely used for military and civilian application. The conventional bulk semiconductor materials based IR cameras suffer from low frame rate, low resolution, temperature dependent and highly cost, while the unusual Carbon Nanotube (CNT), low dimensional material based nanotechnology has been made much progress in research and industry. The unique properties of CNT lead to investigate CNT based IR photodetectors and imaging system, resolving the sensitivity, speed and cooling difficulties in state of the art IR imagings. The reliability and stability is critical to the transition from nano science to nano engineering especially for infrared sensing. It is not only for the fundamental understanding of CNT photoresponse induced processes, but also for the development of a novel infrared sensitive material with unique optical and electrical features. In the proposed research, the sandwich-structured sensor was fabricated within two polymer layers. The substrate polyimide provided sensor with isolation to background noise, and top parylene packing blocked humid environmental factors. At the same time, the fabrication process was optimized by real time electrical detection dielectrophoresis and multiple annealing to improve fabrication yield and sensor performance. The nanoscale infrared photodetector was characterized by digital microscopy and precise linear stage in order for fully understanding it. Besides, the low noise, high gain readout system was designed together with CNT photodetector to make the nano sensor IR camera available. To explore more of infrared light, we employ compressive sensing algorithm into light field sampling, 3-D camera and compressive video sensing. The redundant of whole light field, including angular images for light field, binocular images for 3-D camera and temporal information of video streams, are extracted and

  12. Rapid identification of Chinese Sauce liquor from different fermentation positions with FT-IR spectroscopy

    Science.gov (United States)

    Li, Changwen; Wei, Jiping; Zhou, Qun; Sun, Suqin

    2008-07-01

    FT-IR and two-dimensional correlation spectroscopy (2D-IR) technology were applied to discriminate Chinese Sauce liquor from different fermentation positions (top, middle and bottom of fermentation cellar) for the first time. The liquors at top, middle and bottom of fermentation cellar, possessed the characteristic peaks at 1731 cm -1, 1733 cm -1 and 1602 cm -1, respectively. In the 2D correlation infrared spectra, the differences were amplified. A strong auto-peak at 1725 cm -1 showed in the 2D spectra of the Top Liquor, which indicated that the liquor might contain some ester compounds. Different from Top Liquor, three auto-peaks at 1695, 1590 and 1480 cm -1 were identified in 2D spectra of Middle Liquor, which were the characteristic absorption of acid, lactate. In 2D spectra of Bottom Liquor, two auto-peaks at 1570 and 1485 cm -1 indicated that lactate was the major component. As a result, FT-IR and 2D-IR correlation spectra technology provided a rapid and effective method for the quality analysis of the Sauce liquor.

  13. A full dimensional investigation of infrared spectroscopy of the RbCs dimer using the multi-configuration time-dependent Hartree method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huihui; Yang, Yonggang, E-mail: ygyang@sxu.edu.cn; Xiao, Liantuan; Jia, Suotang [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006 (China)

    2013-12-28

    The geometry and infrared absorption spectrum of (RbCs){sub 2} have been studied by full dimensional quantum dynamics simulations. For this purpose, the potential energy and dipole moment surfaces are generated by means of a cluster expansion with all two and three mode correlations, and fitted to analytical expressions with negligible deviations. Accordingly, the ground state (RbCs){sub 2} has a diamond geometry with D{sub 2h} symmetry. The infrared spectrum with frequencies up to 120 cm{sup −1}, exhibits rich details of the fundamentals, overtones, and combination bands; the highest fundamental frequency of (RbCs){sub 2} is only 40.26 cm{sup −1}. The present study unravels important details of the interactions between the widely investigated ultracold RbCs molecules.

  14. Two-Dimensional Spectroscopy Is Being Used to Address Core Scientific Questions in Biology and Materials Science.

    Science.gov (United States)

    Petti, Megan K; Lomont, Justin P; Maj, Michał; Zanni, Martin T

    2018-02-15

    Two-dimensional spectroscopy is a powerful tool for extracting structural and dynamic information from a wide range of chemical systems. We provide a brief overview of the ways in which two-dimensional visible and infrared spectroscopies are being applied to elucidate fundamental details of important processes in biological and materials science. The topics covered include amyloid proteins, photosynthetic complexes, ion channels, photovoltaics, batteries, as well as a variety of promising new methods in two-dimensional spectroscopy.

  15. Dimensional regularization and infrared divergences in quantum electrodynamics

    International Nuclear Information System (INIS)

    Marculescu, S.

    1979-01-01

    Dimensional continuation was devised as a powerful regularization method for ultraviolet divergences in quantum field theories. Recently it was clear, at least for quantum electrodynamics, that such a method could be employed for factorizing out infrared divergences from the on-shell S-matrix elements. This provides a renormalization scheme on the electron mass-shell without using a gauge violating ''photon mass''. (author)

  16. Lie algebra contractions on two-dimensional hyperboloid

    International Nuclear Information System (INIS)

    Pogosyan, G. S.; Yakhno, A.

    2010-01-01

    The Inoenue-Wigner contraction from the SO(2, 1) group to the Euclidean E(2) and E(1, 1) group is used to relate the separation of variables in Laplace-Beltrami (Helmholtz) equations for the four corresponding two-dimensional homogeneous spaces: two-dimensional hyperboloids and two-dimensional Euclidean and pseudo-Euclidean spaces. We show how the nine systems of coordinates on the two-dimensional hyperboloids contracted to the four systems of coordinates on E 2 and eight on E 1,1 . The text was submitted by the authors in English.

  17. Molecular and functional analysis of DIR1; a novel gene with a potential role in induced radioresistance

    International Nuclear Information System (INIS)

    Young, S.M.; McKeen, H.; Valentine, A.; Burke, G.; Hirst, D.; Robson, T.

    2003-01-01

    Full text: There is now little doubt about the existence of radioprotective mechanisms that are upregulated following exposure to small doses of ionizing radiation and other DNA-damaging agents. The identification of genes whose expression is altered following exposure to a low dose of ionizing radiation will be an important step in understanding these phenomena. We have identified a novel gene, DIR1, that is transiently repressed by low radiation doses (Robson et al.,1997 and 1999) and is otherwise expressed in a wide range of cell lines and tissues. The repression of this gene is in the dose range where induced radioresistance is observed in a number of cell survival studies (Joiner et al., 2001) implicating this gene in induced radioresistance. Using antisense strategies, we have demonstrated that the DIR1 gene product appears to be involved in cell survival and DNA repair in a range of cell lines following exposure to X-rays (Robson et al., 1999 and 2000). Using microchip array analysis we have been able to identify a number of genes activated as a consequence of DIR1 repression. Preliminary data implicate genes involved in repair, cell cycle and stress response and include ATM and BRCA2. We are now confirming these responses using northern and western blot analysis. Yeast two hybrid analysis has also been useful in demonstrating interacting proteins. One protein, which interacts with DIR1 is similar to murine UIP28, a RING finger protein which interacts with the ubiquitin conjugating enzyme, UbcM4. Interestingly, the ubiquitin (Ub)/proteosome pathway regulates many cellular processes including apoptosis, cell cycle progression, stress responses, development and transcriptional regulation. Further characterisation of these downstream genes and interacting proteins will allow us to:- i) dissect the cellular pathways involved in adaptation to oxidative and genotoxic stress ii) elucidate the mechanisms involved in many disease pathologies iii) identify new

  18. A two-dimensional bilayered Cd(II) coordination polymer with a three-dimensional supramolecular architecture incorporating 1,2-bis(pyridin-4-yl)ethene and 2,2'-(diazenediyl)dibenzoic acid.

    Science.gov (United States)

    Liu, Lei-Lei; Zhou, Yan; Li, Ping; Tian, Jiang-Ya

    2014-02-01

    In poly[[μ2-1,2-bis(pyridin-4-yl)ethene-κ(2)N:N'][μ2-2,2'-(diazenediyl)dibenzoato-κ(3)O,O':O'']cadmium(II)], [Cd(C14H8N2O4)(C12H10N2)]n, the asymmetric unit contains one Cd(II) cation, one 2,2'-(diazenediyl)dibenzoate anion (denoted L(2-)) and one 1,2-bis(pyridin-4-yl)ethene ligand (denoted bpe). Each Cd(II) centre is six-coordinated by four O atoms of bridging/chelating carboxylate groups from three L(2-) ligands and by two N atoms from two bpe ligands, forming a distorted octahedron. The Cd(II) cations are bridged by L(2-) and bpe ligands to give a two-dimensional (4,4) layer. The layers are interlinked through bridging carboxylate O atoms from L(2-) ligands, generating a two-dimensional bilayered structure with a 3(6)4(13)6(2) topology. The bilayered structures are further extended to form a three-dimensional supramolecular architecture via a combination of hydrogen-bonding and aromatic stacking interactions.

  19. Dehydration of a layered double hydroxide-C2AH8

    International Nuclear Information System (INIS)

    Ukrainczyk, N.; Matusinovic, T.; Kurajica, S.; Zimmermann, B.; Sipusic, J.

    2007-01-01

    Thermal dehydration of dicalcium aluminate hydrate, C 2 AH 8 , has been investigated by simultaneous differential thermal and thermo gravimetric analysis (DTA/TGA), powder X-ray diffraction (XRD), temperature-dependent infrared spectroscopy (FT-IR), and BET method of surface area measurement. The temperature-dependent infrared measurements were studied by two-dimensional infrared (2D-IR) correlation spectroscopy. The structure of aluminum-oxide polyhedron, characterized by 27 Al solid state NMR spectrum method and FT-IR, shows tetrahedron and octahedron as the main forms of aluminum-oxide polyhedrons in C 2 AH 8 sample. From the results obtained a variety of structural transformations observed are explained as a consequence of the removal of loosely held interlayer water molecules at lower temperatures, followed by grafting process of the interlayer [Al(OH) 4 ] - anion. Structural model of a grafting process of the interlayer [Al(OH) 4 ] - tetrahedron onto hydroxylated octahedrons of [Ca 2 Al(OH) 6 ] + layers has been proposed in order to explain observed loss of one water molecule, shrinkage of interlayer spacing and qualitative changes of FT-IR spectra. At higher temperatures the dehydroxylation of the lattice and decomposition of the interlayer species occurs, yielding amorphous material that crystallizes into C 3 A and C 12 A 7 at 885 deg. C. Those findings provide improvement in the interpretation of thermo-analytical results of calcium aluminate cements (CAC) hydration products, and better understanding of CAC conversion process

  20. Symmetries, holography, and quantum phase transition in two-dimensional dilaton AdS gravity

    Science.gov (United States)

    Cadoni, Mariano; Ciulu, Matteo; Tuveri, Matteo

    2018-05-01

    We revisit the Almheiri-Polchinski dilaton gravity model from a two-dimensional (2D) bulk perspective. We describe a peculiar feature of the model, namely the pattern of conformal symmetry breaking using bulk Killing vectors, a covariant definition of mass and the flow between different vacua of the theory. We show that the effect of the symmetry breaking is both the generation of an infrared scale (a mass gap) and to make local the Goldstone modes associated with the asymptotic symmetries of the 2D spacetime. In this way a nonvanishing central charge is generated in the dual conformal theory, which accounts for the microscopic entropy of the 2D black hole. The use of covariant mass allows to compare energetically the two different vacua of the theory and to show that at zero temperature the vacuum with a constant dilaton is energetically preferred. We also translate in the bulk language several features of the dual CFT discussed by Maldacena et al. The uplifting of the 2D model to (d +2 )-dimensional theories exhibiting hyperscaling violation is briefly discussed.

  1. On two flexible methods of 2-dimensional regression analysis

    Czech Academy of Sciences Publication Activity Database

    Volf, Petr

    2012-01-01

    Roč. 18, č. 4 (2012), s. 154-164 ISSN 1803-9782 Grant - others:GA ČR(CZ) GAP209/10/2045 Institutional support: RVO:67985556 Keywords : regression analysis * Gordon surface * prediction error * projection pursuit Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2013/SI/volf-on two flexible methods of 2-dimensional regression analysis.pdf

  2. Two-dimensional Dirac fermions in thin films of C d3A s2

    Science.gov (United States)

    Galletti, Luca; Schumann, Timo; Shoron, Omor F.; Goyal, Manik; Kealhofer, David A.; Kim, Honggyu; Stemmer, Susanne

    2018-03-01

    Two-dimensional states in confined thin films of the three-dimensional Dirac semimetal C d3A s2 are probed by transport and capacitance measurements under applied magnetic and electric fields. The results establish the two-dimensional Dirac electronic spectrum of these states. We observe signatures of p -type conduction in the two-dimensional states as the Fermi level is tuned across their charge neutrality point and the presence of a zero-energy Landau level, all of which indicate topologically nontrivial states. The resistance at the charge neutrality point is approximately h /e2 and increases rapidly under the application of a magnetic field. The results open many possibilities for gate-tunable topological devices and for the exploration of novel physics in the zero-energy Landau level.

  3. Digital Review of Asia Pacific (DirAP) - Phase II | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    The Digital Review of Asia Pacific (DirAP) has a mission to generate new knowledge ... Call for new OWSD Fellowships for Early Career Women Scientists now open ... IWRA/IDRC webinar on climate change and adaptive water management.

  4. Negative refraction at infrared wavelengths in a two-dimensional photonic crystal

    International Nuclear Information System (INIS)

    Berrier, A.; Mulot, M.; Swillo, M.; Qiu, M.; Thylen, L.; Anand, S.; Talneau, A.

    2004-01-01

    We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area

  5. Studi atas Zikir Tarekat Masyarakat Urban Jemaah Tarîqah Qâdirîyah Naqshabandîyah di Jakarta

    Directory of Open Access Journals (Sweden)

    Ach. Shodiqil Hafil

    2014-10-01

    Full Text Available This article seeks to know the practice of dhikr ritual in Qâdirîyah wa Naqshabandîyah Tariqa that is practiced by the Jakarta urban society. Furthermore, how the community interpret and understand the values of dhikr in the Tariqa. The results of this study indicate that the practice of dhikr in Qâdirîyah wa Naqshabandîyah Tariqa conducted by some of Jakarta urban society is by combining two techniques of dhikr of Allah, the jahr recitation (orally and with loud voice and the khafî zikr (with heart and silently. Besides, Jakarta urban society that follow the Qâdirîyah wa Naqshabandîyah Tariqa interpret dhikr with various arguments. The deeper of knowledge had by the followers of the Tariqa, the deeper of interpretation they will have. Adherents of the Tariqa who have higher level of knowledge do not interpret the practice of dhikr only as sensory motivations, but rather spiritual obligations oriented to togetherness and closeness with God.

  6. (2 + 1)-dimensional interacting model of two massless spin-2 fields as a bi-gravity model

    Science.gov (United States)

    Hoseinzadeh, S.; Rezaei-Aghdam, A.

    2018-06-01

    We propose a new group-theoretical (Chern-Simons) formulation for the bi-metric theory of gravity in (2 + 1)-dimensional spacetime which describe two interacting massless spin-2 fields. Our model has been formulated in terms of two dreibeins rather than two metrics. We obtain our Chern-Simons gravity model by gauging mixed AdS-AdS Lie algebra and show that it has a two dimensional conformal field theory (CFT) at the boundary of the anti de Sitter (AdS) solution. We show that the central charge of the dual CFT is proportional to the mass of the AdS solution. We also study cosmological implications of our massless bi-gravity model.

  7. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao

    2015-02-25

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

  8. Adding a dimension to the infrared spectra of interfaces using heterodyne detected 2D sum-frequency generation (HD 2D SFG) spectroscopy.

    Science.gov (United States)

    Xiong, Wei; Laaser, Jennifer E; Mehlenbacher, Randy D; Zanni, Martin T

    2011-12-27

    In the last ten years, two-dimensional infrared spectroscopy has become an important technique for studying molecular structures and dynamics. We report the implementation of heterodyne detected two-dimensional sum-frequency generation (HD 2D SFG) spectroscopy, which is the analog of 2D infrared (2D IR) spectroscopy, but is selective to noncentrosymmetric systems such as interfaces. We implement the technique using mid-IR pulse shaping, which enables rapid scanning, phase cycling, and automatic phasing. Absorptive spectra are obtained, that have the highest frequency resolution possible, from which we extract the rephasing and nonrephasing signals that are sometimes preferred. Using this technique, we measure the vibrational mode of CO adsorbed on a polycrystalline Pt surface. The 2D spectrum reveals a significant inhomogenous contribution to the spectral line shape, which is quantified by simulations. This observation indicates that the surface conformation and environment of CO molecules is more complicated than the simple "atop" configuration assumed in previous work. Our method can be straightforwardly incorporated into many existing SFG spectrometers. The technique enables one to quantify inhomogeneity, vibrational couplings, spectral diffusion, chemical exchange, and many other properties analogous to 2D IR spectroscopy, but specifically for interfaces.

  9. Two-dimensional errors

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    This chapter addresses the extension of previous work in one-dimensional (linear) error theory to two-dimensional error analysis. The topics of the chapter include the definition of two-dimensional error, the probability ellipse, the probability circle, elliptical (circular) error evaluation, the application to position accuracy, and the use of control systems (points) in measurements

  10. Star formation in the inner galaxy: a far-infrared and radio study of two H2 regions

    International Nuclear Information System (INIS)

    Lester, D.F.; Dinerstein, H.L.; Werner, M.W.; Harvey, P.M.; Evans, N.J.; Brown, R.L.

    1985-09-01

    Far-infrared and radio continuum maps have been made of the central 6' of the inner-galaxy HII regions G30.8-0.0 (in the W43 complex) and G25.4-0.2, along with radio and molecular line measurements at selected positions. The purpose of this study is an effort to understand star formation in the molecular ring at 5 kpc in galactic radius. Measurements at several far infrared wavelengths allow the dust temperature structures and total far infrared fluxes to be determined. Comparison of the radio and infrared maps shows a close relationship between the ionized gas and the infrared-emitting material. There is evidence that parts of G30.8 are substantially affected by extinction, even at far-infrared wavelengths. Using radio recombination line and CO line data for G25.4-0.2, the distance ambiguity for this source is resolved. The large distance previously ascribed to the entire complex is found to apply to only one of the two main components. The confusion in distance determination is found to result from an extraordinary near-superposition of two bright HII regions. Using the revised distances of 4.3 kpc for G25.4SE and 12 kpc for G25.4NW, it is found that the latter, which is apparently the fainter of the two sources, is actually the more luminous. The ratio of total luminosity to ionizing luminosity is very similar to that of HII regions in the solar circle. Assuming a coeval population of ionizing stars, a normal initial mass function is indicated

  11. [The analyses and identification of Flos rhododendri mollis and Flos chrysanthemi indici via infrared spectroscopy].

    Science.gov (United States)

    Jin, Zhe-Xiong; Wang, Yue; Zhou, Qun; Chen, Jian-Bo; Ma, Fang; Sun, Su-Qin

    2014-09-01

    In this study, major chemical components of Flos rhododendri mollis and Flos chrysanthemi indici were characterized using Fourier transform infrared spectroscopy (FTIR). For Flos rhododendri mollis, the bands at 1,648 and 1,543 cm(-1) were attributed to amide I and amide II , respectively, indicating that it contained proteins probably resulting in immunization. In case of Flos chrysanthemi indici, stretching vibration of C==O function group was responsible for the bands at 1,734 and 1,515 cm(-1), as a result of essential oils, lipids, etc. Since FTIR spectra of Flos rhododendri mollis and Flos chrysanthemi indici are almost identical and it is difficult to discriminate them, two-step identification was investigated via secondary derivative of the FTIR spectra. The bands at 1,656 and 1,515 cm(-1) corresponds to flavonoides in Flos rhododendri mollis and Flos chrysanthemi indici. In the secondary derivative of the FTIR spectrum of Flos chrysanthemi indici, characteristic bands of inulin were present at 1,163, 1,077, 1,026, 986 and 869 cm(-1), and therefore Flos chrysanthemi indici contained inulin as well. Tri-step identification was carried out for Flos rhododendri mollis and Flos chrysanthemi indici by means of comparing their 2D-IR correlation spectra in different wave number range. In the characteristic range of flavonoides (1,700-1,400 cm(-1)), Flos rhododendri mollis exhibited 3 obvious autopeaks, while 10 autopeaks were visualized in the 2D-IR correlation spectrum of Flos chrysanthemi indici Moreover, in the characteristic range of glucoside (1,250-900 cm(-1)), 10 and 9 autopeaks were present in the 2D-IR correlation spectra of Flos rhododendri mollis and Flos chrysanthemi indici, respectively. Therefore, the tri-step identification of FTIR is a time-saving; accurate, cost-saving and convenient method to effectively distinguish traditional Chinese medicines.

  12. Radiation effects on two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Walker, R.C. II; Robinson, J.A. [Department of Materials Science, Penn State, University Park, PA (United States); Center for Two-Dimensional Layered Materials, Penn State, University Park, PA (United States); Shi, T. [Department of Mechanical and Nuclear Engineering, Penn State, University Park, PA (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Silva, E.C. [GlobalFoundries, Malta, NY (United States); Jovanovic, I. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)

    2016-12-15

    The effects of electromagnetic and particle irradiation on two-dimensional materials (2DMs) are discussed in this review. Radiation creates defects that impact the structure and electronic performance of materials. Determining the impact of these defects is important for developing 2DM-based devices for use in high-radiation environments, such as space or nuclear reactors. As such, most experimental studies have been focused on determining total ionizing dose damage to 2DMs and devices. Total dose experiments using X-rays, gamma rays, electrons, protons, and heavy ions are summarized in this review. We briefly discuss the possibility of investigating single event effects in 2DMs based on initial ion beam irradiation experiments and the development of 2DM-based integrated circuits. Additionally, beneficial uses of irradiation such as ion implantation to dope materials or electron-beam and helium-beam etching to shape materials have begun to be used on 2DMs and are reviewed as well. For non-ionizing radiation, such as low-energy photons, we review the literature on 2DM-based photo-detection from terahertz to UV. The majority of photo-detecting devices operate in the visible and UV range, and for this reason they are the focus of this review. However, we review the progress in developing 2DMs for detecting infrared and terahertz radiation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Novel target design algorithm for two-dimensional optical storage (TwoDOS)

    NARCIS (Netherlands)

    Huang, Li; Chong, T.C.; Vijaya Kumar, B.V.K.; Kobori, H.

    2004-01-01

    In this paper we introduce the Hankel transform based channel model of Two-Dimensional Optical Storage (TwoDOS) system. Based on this model, the two-dimensional (2D) minimum mean-square error (MMSE) equalizer has been derived and applied to some simple but common cases. The performance of the 2D

  14. Two-dimensional models

    International Nuclear Information System (INIS)

    Schroer, Bert; Freie Universitaet, Berlin

    2005-02-01

    It is not possible to compactly review the overwhelming literature on two-dimensional models in a meaningful way without a specific viewpoint; I have therefore tacitly added to the above title the words 'as theoretical laboratories for general quantum field theory'. I dedicate this contribution to the memory of J. A. Swieca with whom I have shared the passion of exploring 2-dimensional models for almost one decade. A shortened version of this article is intended as a contribution to the project 'Encyclopedia of mathematical physics' and comments, suggestions and critical remarks are welcome. (author)

  15. A flow system for generation of concentration perturbation in two-dimensional correlation near-infrared spectroscopy: application to variable selection in multivariate calibration.

    Science.gov (United States)

    Pereira, Claudete Fernandes; Pasquini, Celio

    2010-05-01

    A flow system is proposed to produce a concentration perturbation in liquid samples, aiming at the generation of two-dimensional correlation near-infrared spectra. The system presents advantages in relation to batch systems employed for the same purpose: the experiments are accomplished in a closed system; application of perturbation is rapid and easy; and the experiments can be carried out with micro-scale volumes. The perturbation system has been evaluated in the investigation and selection of relevant variables for multivariate calibration models for the determination of quality parameters of gasoline, including ethanol content, MON (motor octane number), and RON (research octane number). The main advantage of this variable selection approach is the direct association between spectral features and chemical composition, allowing easy interpretation of the regression models.

  16. The retrieval of two-dimensional distribution of the earth's surface aerodynamic roughness using SAR image and TM thermal infrared image

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Renhua; WANG; Jinfeng; ZHU; Caiying; SUN; Xiaomin

    2004-01-01

    After having analyzed the requirement on the aerodynamic earth's surface roughness in two-dimensional distribution in the research field of interaction between land surface and atmosphere, this paper presents a new way to calculate the aerodynamic roughness using the earth's surface geometric roughness retrieved from SAR (Synthetic Aperture Radar) and TM thermal infrared image data. On the one hand, the SPM (Small Perturbation Model) was used as a theoretical SAR backscattering model to describe the relationship between the SAR backscattering coefficient and the earth's surface geometric roughness and its dielectric constant retrieved from the physical model between the soil thermal inertia and the soil surface moisture with the simultaneous TM thermal infrared image data and the ground microclimate data. On the basis of the SAR image matching with the TM image, the non-volume scattering surface geometric information was obtained from the SPM model at the TM image pixel scale, and the ground pixel surface's equivalent geometric roughness-height standard RMS (Root Mean Square) was achieved from the geometric information by the transformation of the typical topographic factors. The vegetation (wheat, tree) height retrieved from spectrum model was also transferred into its equivalent geometric roughness. A completely two-dimensional distribution map of the equivalent geometric roughness over the experimental area was produced by the data mosaic technique. On the other hand, according to the atmospheric eddy currents theory, the aerodynamic surface roughness was iterated out with the atmosphere stability correction method using the wind and the temperature profiles data measured at several typical fields such as bare soil field and vegetation field. After having analyzed the effect of surface equivalent geometric roughness together with dynamic and thermodynamic factors on the aerodynamic surface roughness within the working area, this paper first establishes a scale

  17. GPM GROUND VALIDATION TWO-DIMENSIONAL VIDEO DISDROMETER (2DVD) IPHEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) IPHEx dataset was collected during the GPM Ground Validation Integrated Precipitation and...

  18. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    Directory of Open Access Journals (Sweden)

    Nikola Stefanović

    2007-06-01

    Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.

  19. Investigating vibrational anharmonic couplings in cyanide-bridged transition metal mixed valence complexes using two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Slenkamp, Karla M.; Lynch, Michael S.; Van Kuiken, Benjamin E.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira, E-mail: mkhalil@chem.washington.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2014-02-28

    Using polarization-selective two-dimensional infrared (2D IR) spectroscopy, we measure anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching (ν{sub CN}) vibrations found in [(NH{sub 3}){sub 5}Ru{sup III}NCFe{sup II}(CN){sub 5}]{sup −} (FeRu) dissolved in D{sub 2}O and formamide and [(NC){sub 5}Fe{sup II}CNPt{sup IV}(NH{sub 3}){sub 4}NCFe{sup II}(CN){sub 5}]{sup 4−} (FePtFe) dissolved in D{sub 2}O. These cyanide-bridged transition metal complexes serve as model systems for studying the role of high frequency vibrational modes in ultrafast photoinduced charge transfer reactions. Here, we focus on the spectroscopy of the ν{sub CN} modes in the electronic ground state. The FTIR spectra of the ν{sub CN} modes of the bimetallic and trimetallic systems are strikingly different in terms of frequencies, amplitudes, and lineshapes. The experimental 2D IR spectra of FeRu and FePtFe and their fits reveal a set of weakly coupled anharmonic ν{sub CN} modes. The vibrational mode anharmonicities of the individual ν{sub CN} modes range from 14 to 28 cm{sup −1}. The mixed-mode anharmonicities range from 2 to 14 cm{sup −1}. In general, the bridging ν{sub CN} mode is most weakly coupled to the radial ν{sub CN} mode, which involves the terminal CN ligands. Measurement of the relative transition dipole moments of the four ν{sub CN} modes reveal that the FeRu molecule is almost linear in solution when dissolved in formamide, but it assumes a bent geometry when dissolved in D{sub 2}O. The ν{sub CN} modes are modelled as bilinearly coupled anharmonic oscillators with an average coupling constant of 6 cm{sup −1}. This study elucidates the role of the solvent in modulating the molecular geometry and the anharmonic vibrational couplings between the ν{sub CN} modes in cyanide-bridged transition metal mixed valence complexes.

  20. Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-05-07

    Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

  1. Two-dimensional MoS2 electromechanical actuators

    Science.gov (United States)

    Hung, Nguyen T.; Nugraha, Ahmad R. T.; Saito, Riichiro

    2018-02-01

    We investigate the electromechanical properties of two-dimensional MoS2 monolayers with 1H, 1T, and 1T‧ structures as a function of charge doping by using density functional theory. We find isotropic elastic moduli in the 1H and 1T structures, while the 1T‧ structure exhibits an anisotropic elastic modulus. Moreover, the 1T structure is shown to have a negative Poisson’s ratio, while Poisson’s ratios of the 1H and 1T‧ are positive. By charge doping, the monolayer MoS2 shows a reversible strain and work density per cycle ranging from  -0.68% to 2.67% and from 4.4 to 36.9 MJ m-3, respectively, making them suitable for applications in electromechanical actuators. We also examine the stress generated in the MoS2 monolayers and we find that 1T and 1T‧ MoS2 monolayers have relatively better performance than 1H MoS2 monolayer. We argue that such excellent electromechanical performance originate from the electrical conductivity of the metallic 1T and semimetallic 1T‧ structures and also from their high Young’s modulus of about 150-200 GPa.

  2. Electronic configuration of the c(2 x 2)MnCu two-dimensional alloy in layered structures supported on Cu(100)

    International Nuclear Information System (INIS)

    Gallego, S; Munoz, M C; Huttel, Y; Avila, J; Asensio, M C

    2003-01-01

    The c(2 x 2)MnCu surface alloy on Cu(100) can be considered as a purely two-dimensional magnetic system where the Mn atoms exhibit a large corrugation closely related to their high spin moment. In this paper we investigate the influence of the atomic environment on the electronic and magnetic properties of the two-dimensional alloyed layer, extending our study to the less known multilayered system made of MnCu two-dimensional alloy layers embedded in a Cu crystal. The analysis is based on angle-resolved photoelectron spectroscopy measurements and calculations using the Green function matching method, which allows us to treat exactly the projection of the three-dimensional lattice on the c(2 x 2) plane. A complete study of the valence band is performed along the two-dimensional Brillouin zone in a wide energy range. We show that the presence of Mn results in an important redistribution of the spin-polarized electronic states of the neighbouring Cu atoms. This redistribution is not accompanied by a net charge transfer between different atoms, and also the spin moment of Cu remains small. Most of the new features induced by Mn in the surface alloy are also present in the multilayered system, evidencing that they are specific to the two-dimensional alloyed layer and not surface effects

  3. Fe/Co doped molybdenum diselenide: a promising two-dimensional intermediate-band photovoltaic material

    International Nuclear Information System (INIS)

    Zhang, Jiajia; He, Haiyan; Pan, Bicai

    2015-01-01

    An intermediate-band (IB) photovoltaic material is an important candidate in developing the new-generation solar cell. In this paper, we propose that the Fe-doped or the Co-doped MoSe 2 just meets the required features in IB photovoltaic materials. Our calculations demonstrate that when the concentration of the doped element reaches 11.11%, the doped MoSe 2 shows a high absorptivity for both infrared and visible light, where the photovoltaic efficiency of the doped MoSe 2 is as high as 56%, approaching the upper limit of photovoltaic efficiency of IB materials. So, the Fe- or Co-doped MoSe 2 is a promising two-dimensional photovoltaic material. (paper)

  4. The emergence of geometry: a two-dimensional toy model

    CERN Document Server

    Alfaro, Jorge; Puigdomenech, Daniel

    2010-01-01

    We review the similarities between the effective chiral lagrangrian, relevant for low-energy strong interactions, and the Einstein-Hilbert action. We use these analogies to suggest a specific mechanism whereby gravitons would emerge as Goldstone bosons of a global SO(D) X GL(D) symmetry broken down to SO(D) by fermion condensation. We propose a two-dimensional toy model where a dynamical zwei-bein is generated from a topological theory without any pre-existing metric structure, the space being endowed only with an affine connection. A metric appears only after the symmetry breaking; thus the notion of distance is an induced effective one. In spite of several non-standard features this simple toy model appears to be renormalizable and at long distances is described by an effective lagrangian that corresponds to that of two-dimensional gravity (Liouville theory). The induced cosmological constant is related to the dynamical mass M acquired by the fermion fields in the breaking, which also acts as an infrared re...

  5. The two-dimensional thiophosphate CsCrP2S7

    Directory of Open Access Journals (Sweden)

    Kyounghee Kim

    2010-09-01

    Full Text Available The quaternary title compound, caesium chromium(III heptathiodiphosphate(V, CsCrP2S7, has been synthesized using the reactive halide flux method. It is isotypic with other AMP2S7 (A = alkali metal; M = Cr, V or In structures and consists of two-dimensional2[CrP2S7]− layers extending parallel to (001 which are separated from each other by Cs+ ions (symmetry 2. The layer is built up from slightly distorted octahedral [CrS6] units (symmetry 2 and bent [P2S7] units consisting of two corner-sharing [PS4] tetrahedra. The [CrS6] octahedra share two edges and two corners with the [PS4] tetrahedra. There are only van der Waals interactions present between the layers. The Cs+ ions are located in this van der Waals gap and stabilize the structure through weak ionic interactions. The classical charge balance of the title compound can be expressed as [Cs+][Cr3+][P5+]2[S2−]7.

  6. GPM GROUND VALIDATION TWO-DIMENSIONAL VIDEO DISDROMETER (2DVD) IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) IFloodS dataset was collected during the GPM Ground Validation Iowa Flood Studies (IFloodS) field...

  7. Insight into the Local Solvent Environment of Biologically Relevant Iron-nitroysl Systems through Two-Dimensional Infrared Spectroscopy

    Science.gov (United States)

    Brookes, Jennifer Faith

    Iron-nitrosyl systems, particularly in the form of heme proteins, with their iron metal active sites play an important role in biological systems. Heme proteins act as storage, transporters, and receptors for nitric oxide (NO), a signaling molecule that is important in immune, nervous, and cardiovascular systems of mammals. By better understanding the local environment of the active site of NO binding heme proteins we can gain insight into disease in which the NO pathways have been implicated. This is an important step to being able to develop pharmaceuticals targeting NO pathways in humans. Sodium nitroprusside ((SNP, Na2[Fe(CN)5is NO]·2H 2O) investigated as a model system for the active site of nitric oxide binding heme proteins. Using two-dimensional infrared spectroscopy (2D IR) to obtain dephasing dynamics of the nitrosyl stretch (nuNO) in a series of solvents we are able to better understand the local environment of the more complicated metalloproteins. Rigorous line shape analysis is performed by using nonlinear response theory to simulate 2D IR spectra which are then fit to experimental data in an iterative process to extract frequency-frequency correlation functions (FFCFs). The time scales obtained are then correlated to empirical solvent polarity parameters. The analysis of the 2D IR lineshapes reveal that the spectral diffusion timescale of the nuNO in SNP varies from 0.8 -- 4 ps and is negatively correlated with the empirical solvent polarity scales. We continue to investigate NO binding of metalloproteins through 2D IR experiments on nitrophorin 4 (NP4). NP4 is a pH-sensitive NO transporter protein present in the salivary gland of the blood sucking insect Rhodius prolixus which undergoes a pH sensitive structural change between a closed and open conformation allowing for the storage and delivery of NO. The two structures are observed spectroscopically as two distinct pH-dependent nu NO frequencies at ~1904 and ~1917 cm-1. We obtain FFCFs by globally

  8. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Science.gov (United States)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-08-01

    We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester Cdbnd O and diazo Ndbnd N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency-frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single Cdbnd O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  9. Status for the two-dimensional Navier-Stokes solver EllipSys2D

    DEFF Research Database (Denmark)

    Bertagnolio, F.; Sørensen, Niels N.; Johansen, J.

    2001-01-01

    This report sets up an evaluation of the two-dimensional Navier-Stokes solver EllipSys2D in its present state. This code is used for blade aerodynamics simulations in the Aeroelastic Design group at Risø. Two airfoils are investigated by computing theflow at several angles of attack ranging from...

  10. Identifying Two-Dimensional Z 2 Antiferromagnetic Topological Insulators

    Science.gov (United States)

    Bègue, F.; Pujol, P.; Ramazashvili, R.

    2018-01-01

    We revisit the question of whether a two-dimensional topological insulator may arise in a commensurate Néel antiferromagnet, where staggered magnetization breaks the symmetry with respect to both elementary translation and time reversal, but retains their product as a symmetry. In contrast to the so-called Z 2 topological insulators, an exhaustive characterization of antiferromagnetic topological phases with the help of topological invariants has been missing. We analyze a simple model of an antiferromagnetic topological insulator and chart its phase diagram, using a recently proposed criterion for centrosymmetric systems [13]. We then adapt two methods, originally designed for paramagnetic systems, and make antiferromagnetic topological phases manifest. The proposed methods apply far beyond the particular examples treated in this work, and admit straightforward generalization. We illustrate this by two examples of non-centrosymmetric systems, where no simple criteria have been known to identify topological phases. We also present, for some cases, an explicit construction of edge states in an antiferromagnetic topological insulator.

  11. N = 2 two dimensional Wess-Zumino model on the lattice

    International Nuclear Information System (INIS)

    Elitzur, S.; Schwimmer, A.

    1983-04-01

    A lattice version of the N = 2 SUSY two dimensional Wess-Zumino model was constructed and studied. The correct continuum limit is checked in perturbation theory. The strong coupling limit is defined and investigated. We find that the ground state of the model has zero energy and infinite degeneracy. The connection between this degeneracy and the properties of the Nicolai-Parisi-Sourlas transformation is discussed. (author)

  12. Deformations of infrared-conformal theories in two dimensions

    CERN Document Server

    Akerlund, Oscar

    2014-01-01

    We study two exactly solvable two-dimensional conformal models, the critical Ising model and the Sommerfield model, on the lattice. We show that finite-size effects are important and depend on the aspect ratio of the lattice. In particular, we demonstrate how to obtain the correct massless behavior from an infinite tower of finite-size-induced masses and show that it is necessary to first take the cylindrical geometry limit in order to get correct results. In the Sommerfield model we also introduce a mass deformation to measure the mass anomalous dimension, $\\gamma_m$. We find that the explicit scale breaking of the lattice setup induces corrections which must be taken into account in order to reproduce $\\gamma_m$ at the infrared fixed point. These results can be used to improve the methodology in the search for the conformal window in QCD-like theories with many flavors.

  13. Evaluation of the performance of deformable image registration between planning CT and CBCT images for the pelvic region: comparison between hybrid and intensity-based DIR.

    Science.gov (United States)

    Takayama, Yoshiki; Kadoya, Noriyuki; Yamamoto, Takaya; Ito, Kengo; Chiba, Mizuki; Fujiwara, Kousei; Miyasaka, Yuya; Dobashi, Suguru; Sato, Kiyokazu; Takeda, Ken; Jingu, Keiichi

    2017-07-01

    This study aimed to evaluate the performance of the hybrid deformable image registration (DIR) method in comparison with intensity-based DIR for pelvic cone-beam computed tomography (CBCT) images, using intensity and anatomical information. Ten prostate cancer patients treated with intensity-modulated radiation therapy (IMRT) were studied. Nine or ten CBCT scans were performed for each patient. First, rigid registration was performed between the planning CT and all CBCT images using gold fiducial markers, and then DIR was performed. The Dice similarity coefficient (DSC) and center of mass (COM) displacement were used to evaluate the quantitative DIR accuracy. The average DSCs for intensity-based DIR for the prostate, rectum, bladder, and seminal vesicles were 0.84 ± 0.05, 0.75 ± 0.05, 0.69 ± 0.07 and 0.65 ± 0.11, respectively, whereas those values for hybrid DIR were 0.98 ± 0.00, 0.97 ± 0.01, 0.98 ± 0.00 and 0.94 ± 0.03, respectively (P DSC for hybrid DIR had a higher DSC value and smaller COM displacement for all structures and all patients, compared with intensity-based DIR. Thus, the accumulative dose based on hybrid DIR might be trusted as a high-precision dose estimation method that takes into account organ movement during treatment radiotherapy. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  14. A theoretical study on the electronic property of a new two-dimensional material molybdenum dinitride

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Haiping, E-mail: mrhpwu@njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Qian, Yan, E-mail: qianyan@njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Lu, Ruifeng; Tan, Weishi [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2016-02-15

    Motivated by the recent synthesis of bulk MoN{sub 2} which exhibits the layered structure just like the bulk MoS{sub 2}, the monolayered MoN{sub 2} exfoliated from the bulk counterpart is investigated systematically by using density-functional calculations in this work. The result shows that the ground-state two-dimensional monolayered MoN{sub 2} behaves as an indirect band gap semiconductor with the energy gap of ∼0.12 eV. Subsequently, the external strain from −6% to 6% is employed to engineer the band structure, and the energy gap can be efficiently tuned from 0 to 0.70 eV. Notably, when the strain is beyond 5% or −3%, the two-dimensional monolayered MoN{sub 2} would transfer from an indirect band gap to a direct band gap semiconductor. This work introduces a new member of two-dimensional transition-metal family, which is important for industry applications, especially for the utilization in the long-wavelength infrared field. - Highlights: • The 2D MoN{sub 2} behaves as an indirect band gap semiconductor with the energy gap of ∼0.12 eV. • The energy gap can be efficiently tuned from 0 to 0.70 eV by small strain. • The band gap would transfer from an indirect to a direct one when the strain is beyond 5% or −3%.

  15. Two-dimensional x-ray diffraction

    CERN Document Server

    He, Bob B

    2009-01-01

    Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea

  16. Fully automated dual-frequency three-pulse-echo 2DIR spectrometer accessing spectral range from 800 to 4000 wavenumbers

    Energy Technology Data Exchange (ETDEWEB)

    Leger, Joel D.; Nyby, Clara M.; Varner, Clyde; Tang, Jianan; Rubtsova, Natalia I.; Yue, Yuankai; Kireev, Victor V.; Burtsev, Viacheslav D.; Qasim, Layla N.; Rubtsov, Igor V., E-mail: irubtsov@tulane.edu [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Rubtsov, Grigory I. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312 (Russian Federation)

    2014-08-15

    A novel dual-frequency two-dimensional infrared instrument is designed and built that permits three-pulse heterodyned echo measurements of any cross-peak within a spectral range from 800 to 4000 cm{sup −1} to be performed in a fully automated fashion. The superior sensitivity of the instrument is achieved by a combination of spectral interferometry, phase cycling, and closed-loop phase stabilization accurate to ∼70 as. The anharmonicity of smaller than 10{sup −4} cm{sup −1} was recorded for strong carbonyl stretching modes using 800 laser shot accumulations. The novel design of the phase stabilization scheme permits tuning polarizations of the mid-infrared (m-IR) pulses, thus supporting measurements of the angles between vibrational transition dipoles. The automatic frequency tuning is achieved by implementing beam direction stabilization schemes for each m-IR beam, providing better than 50 μrad beam stability, and novel scheme for setting the phase-matching geometry for the m-IR beams at the sample. The errors in the cross-peak amplitudes associated with imperfect phase matching conditions and alignment are found to be at the level of 20%. The instrument can be used by non-specialists in ultrafast spectroscopy.

  17. Interfacial nondegenerate doping of MoS2 and other two-dimensional semiconductors.

    Science.gov (United States)

    Behura, Sanjay; Berry, Vikas

    2015-03-24

    Controlled nondegenerate doping of two-dimensional semiconductors (2DSs) with their ultraconfined carriers, high quantum capacitance, and surface-sensitive electronics can enable tuning their Fermi levels for rational device design. However, doping techniques for three-dimensional semiconductors, such as ion implantation, cannot be directly applied to 2DSs because they inflict high defect density. In this issue of ACS Nano, Park et al. demonstrate that interfacing 2DSs with substrates having dopants can controllably inject carriers to achieve nondegenerate doping, thus significantly broadening 2DSs' functionality and applications. Futuristically, this can enable complex spatial patterning/contouring of energy levels in 2DSs to form p-n junctions, integrated logic, and opto/electronic devices. The process is also extendable to biocellular-interfaced devices, band-continuum structures, and intricate 2D circuitry.

  18. Center Line Slope Analysis in Two-Dimensional Electronic Spectroscopy

    OpenAIRE

    ?anda, Franti?ek; Perl?k, V?clav; Lincoln, Craig N.; Hauer, J?rgen

    2015-01-01

    Center line slope (CLS) analysis in 2D infrared spectroscopy has been extensively used to extract frequency?frequency correlation functions of vibrational transitions. We apply this concept to 2D electronic spectroscopy, where CLS is a measure of electronic gap fluctuations. The two domains, infrared and electronic, possess differences: In the infrared, the frequency fluctuations are classical, often slow and Gaussian. In contrast, electronic spectra are subject to fast spectral diffusion and...

  19. Role of thermal two-phonon scattering for impurity dynamics in a low-dimensional Bose-Einstein condensate

    Science.gov (United States)

    Lausch, Tobias; Widera, Artur; Fleischhauer, Michael

    2018-03-01

    We numerically study the relaxation dynamics of a single, heavy impurity atom interacting with a finite one- or two-dimensional, ultracold Bose gas. While there is a clear separation of time scales between processes resulting from single- and two-phonon scattering in three spatial dimensions, the thermalization in lower dimensions is dominated by two-phonon processes. This is due to infrared divergences in the corresponding scattering rates in the thermodynamic limit, which are a manifestation of the Mermin-Wagner-Hohenberg theorem. This makes it necessary to include second-order phonon scattering above a crossover temperature T2ph . T2ph scales inversely with the system size and is much smaller than currently experimentally accessible.

  20. Asymptotics for Two-dimensional Atoms

    DEFF Research Database (Denmark)

    Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip

    2012-01-01

    We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....

  1. Two-dimensional sum-frequency generation (2D SFG) reveals structure and dynamics of a surface-bound peptide

    Science.gov (United States)

    Laaser, Jennifer E.; Skoff, David R.; Ho, Jia-Jung; Joo, Yongho; Serrano, Arnaldo L.; Steinkruger, Jay D.; Gopalan, Padma; Gellman, Samuel H.; Zanni, Martin T.

    2014-01-01

    Surface-bound polypeptides and proteins are increasingly used to functionalize inorganic interfaces such as electrodes, but their structural characterization is exceedingly difficult with standard technologies. In this paper, we report the first two-dimensional sum-frequency generation (2D SFG) spectra of a peptide monolayer, which is collected by adding a mid-IR pulse shaper to a standard femtosecond SFG spectrometer. On a gold surface, standard FTIR spectroscopy is inconclusive about the peptide structure because of solvation-induced frequency shifts, but the 2D lineshapes, anharmonic shifts, and lifetimes obtained from 2D SFG reveal that the peptide is largely α-helical and upright. Random coil residues are also observed, which do not themselves appear in SFG spectra due to their isotropic structural distribution, but which still absorb infrared light and so can be detected by cross-peaks in 2D SFG spectra. We discuss these results in the context of peptide design. Because of the similar way in which the spectra are collected, these 2D SFG spectra can be directly compared to 2D IR spectra, thereby enabling structural interpretations of surface-bound peptides and biomolecules based on the well-studied structure/2D IR spectra relationships established from soluble proteins. PMID:24372101

  2. Emergence of geometry: A two-dimensional toy model

    International Nuclear Information System (INIS)

    Alfaro, Jorge; Espriu, Domene; Puigdomenech, Daniel

    2010-01-01

    We review the similarities between the effective chiral Lagrangrian, relevant for low-energy strong interactions, and the Einstein-Hilbert action. We use these analogies to suggest a specific mechanism whereby gravitons would emerge as Goldstone bosons of a global SO(D)xGL(D) symmetry broken down to SO(D) by fermion condensation. We propose a two-dimensional toy model where a dynamical zweibein is generated from a topological theory without any preexisting metric structure, the space being endowed only with an affine connection. A metric appears only after the symmetry breaking; thus the notion of distance is an induced effective one. In spite of several nonstandard features this simple toy model appears to be renormalizable and at long distances is described by an effective Lagrangian that corresponds to that of two-dimensional gravity (Liouville theory). The induced cosmological constant is related to the dynamical mass M acquired by the fermion fields in the breaking, which also acts as an infrared regulator. The low-energy expansion is valid for momenta k>M, i.e. for supra-horizon scales. We briefly discuss a possible implementation of a similar mechanism in four dimensions.

  3. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao; Zhang, Hua

    2015-01-01

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards

  4. Long-Range Vibrational Dynamics Are Directed by Watson-Crick Base Pairing in Duplex DNA.

    Science.gov (United States)

    Hithell, Gordon; Shaw, Daniel J; Donaldson, Paul M; Greetham, Gregory M; Towrie, Michael; Burley, Glenn A; Parker, Anthony W; Hunt, Neil T

    2016-05-05

    Ultrafast two-dimensional infrared (2D-IR) spectroscopy of a 15-mer A-T DNA duplex in solution has revealed structure-dependent vibrational coupling and energy transfer processes linking bases with the sugar-phosphate backbone. Duplex melting induces significant changes in the positions of off-diagonal peaks linking carbonyl and ring-stretching vibrational modes of the adenine and thymine bases with vibrations of the phosphate group and phosphodiester linkage. These indicate that Watson-Crick hydrogen bonding and helix formation lead to a unique vibrational coupling arrangement of base vibrational modes with those of the phosphate unit. On the basis of observations from time-resolved 2D-IR data, we conclude that rapid energy transfer processes occur between base and backbone, mediated by additional modes located on the deoxyribose moiety within the same nucleotide. These relaxation dynamics are insensitive to duplex melting, showing that efficient intramolecular energy relaxation to the solvent via the phosphate groups is the key to excess energy dissipation in both single- and double-stranded DNA.

  5. Nucleation front instability in two-dimensional (2D) nanosheet gadolinium-doped cerium oxide (CGO) formation

    DEFF Research Database (Denmark)

    Marani, Debora; Moraes, Leticia Poras Reis; Gualandris, Fabrizio

    2018-01-01

    Herein we report for the first time the synthesis of ceramic–organic three-dimensional (3D) layered gadolinium-doped cerium oxide (Ce1−XGdXO2−δ, CGO) and its exfoliation into two-dimensional (2D) nanosheets. We adopt a water-based synthetic route via a homogenous precipitation approach at low...... temperatures (10–80 °C). The reaction conditions are tuned to investigate the effects of thermal energy on the final morphology. A low temperature (40 °C) morphological transition from nanoparticles (1D) to two-dimensional (2D) nanosheets is observed and associated with a low thermal energy transition of ca. 2.......6 kJ mol−1. For the 3D-layered material, exfoliation experiments are conducted in water/ethanol solutions. Systems at volume fractions ranging from 0.15 to 0.35 are demonstrated to promote under ultrasonic treatment the delamination into 2D nanosheets....

  6. Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS2 systems

    KAUST Repository

    Cheng, Yingchun

    2013-03-05

    Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X=Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.

  7. Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation

    Directory of Open Access Journals (Sweden)

    Arendt-Nielsen Lars

    2010-11-01

    Full Text Available Abstract Background CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers. Methods In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. Results The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p 0.90, p 2 (5 W, 0.12 s, d1/e2 = 11.4 mm only two reported pain to glabrous skin stimulation using the same stimulus intensity. The temperature at the epidermal-dermal junction (depth 50 μm in hairy and depth 133 μm in glabrous skin was estimated to 46°C for hairy skin stimulation and 39°C for glabrous skin stimulation. Conclusions As compared to previous one dimensional heat distribution models, the current two dimensional model provides new possibilities for detailed studies regarding CO2 laser stimulation intensity, temperature levels and nociceptor activation.

  8. Three-dimensional isotropic T2-weighted cervical MRI at 3 T: Comparison with two-dimensional T2-weighted sequences

    International Nuclear Information System (INIS)

    Kwon, J.W.; Yoon, Y.C.; Choi, S.-H.

    2012-01-01

    Aim: To compare three-dimensional (3D) isotropic T2-weighted magnetic resonance imaging (MRI) sequences and reformation with two-dimensional (2D) T2-weighted sequences regarding image quality of the cervical spine at 3 T. Materials and methods: A phantom study was performed using a water-filled cylinder. The signal-to-noise and image homogeneity were evaluated. Fourteen (n = 14) volunteers were examined at 3 T using 3D isotropic T2-weighted sagittal and conventional 2D T2-weighted sagittal, axial, and oblique sagittal MRI. Multiplanar reformation (MPR) of the 3D T2-weighted sagittal dataset was performed simultaneously with image evaluation. In addition to artefact assessment, the visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen’s kappa and Wilcoxon signed rank test were used for the statistical analysis. Result: The 3D isotropic T2-weighted sequence resulted in the highest signal-to-noise ratio (SNR) and lowest non-uniformity (NU) among the sequences in the phantom study. Quantitative evaluation revealed lower NU values of the cerebrospinal fluid (CSF) and muscles in 2D T2-weighted sagittal sequences compared to the 3D volume isotropic turbo spin-echo acquisition (VISTA) sequence. The other NU values revealed no statistically significant difference between the 2D turbo spin-echo (TSE) and 3D VISTA sequences (0.059 < p < 0.959). 3D VISTA images showed significantly fewer CSF flow artefacts (p < 0.001) and better delineated intradural nerve rootlets (p = 0.001) and neural foramina (p = 0.016) compared to 2D sequences. Conclusion: A 3D T2 weighted sequence is superior to conventional 2D sequences for the delineation of intradural nerve rootlets and neural foramina and is less affected by CSF flow artefacts.

  9. Infrared problems in field perturbation theory

    International Nuclear Information System (INIS)

    David, Francois.

    1982-12-01

    The work presented mainly covers questions related to the presence of ''infrared'' divergences in perturbation expansions of the Green functions of certain massless field theories. It is important to determine the mathematical status of perturbation expansions in field theory in order to define the region in which they are valid. Renormalization and the symmetry of a theory are important factors in infrared problems. The main object of this thesis resides in the mathematical techniques employed: integral representations of the Feynman amplitudes; methods for desingularization, regularization and dimensional renormalization. Nonlinear two dimensional space-time sigma models describing Goldstone's low energy boson dynamics associated with a breaking of continuous symmetry are studied. Random surface models are then investigated followed by infrared divergences in super-renormalizable theories. Finally, nonperturbation effects in massless theories are studied by expanding the two-dimensional nonlinear sigma model in 1/N [fr

  10. Bi[NC5H3(CO2)2](OH2)xF (x=1 and 2): New one-dimensional Bi-coordination materials—Reversible hydration and topotactic decomposition to α-Bi2O3

    Science.gov (United States)

    Jeon, Hye Rim; Lee, Dong Woo; Ok, Kang Min

    2012-03-01

    Two one-dimensional bismuth-coordination materials, Bi[NC5H3(CO2)2](OH2)xF (x=1 and 2), have been synthesized by hydrothermal reactions using Bi2O3, 2,6-NC5H3(CO2H)2, HF, and water at 180 °C. Structures of the two materials were determined by single-crystal X-ray diffraction. Although they have different crystal structures, both Bi-organic materials shared a common structural motif, a one-dimensional chain structure consisting of Bi3+ cations and pyridine dicarboxylate linkers. Detailed structural analyses include infrared spectroscopy, thermogravimetric analysis, and reversible hydration reactions for the coordinated water molecules were reported. Also, thermal decomposition of the rod-shaped Bi[NC5H3(CO2)2](OH2)F single crystals at 800 °C led to α-Bi2O3 that maintained the same morphology of the original crystals.

  11. Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sarycheva, Asia [Drexel Univ., Philadelphia, PA (United States); Makaryan, Taron [Drexel Univ., Philadelphia, PA (United States); Maleski, Kathleen [Drexel Univ., Philadelphia, PA (United States); Satheeshkumar, Elumalai [National Cheng Kung Univ., Tainan (Taiwan); National Institute of Technology-Trichy, Tamil Nadu (India); Melikyan, Armen [Russian-Armenian (Slavonic) State Univ., Yerevan (Armenia); Minassian, Hayk [A. Alikhanian National Science Lab., Yerevan (Armenia); Yoshimura, Masahiro [National Cheng Kung Univ., Tainan (Taiwan); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

    2017-08-22

    Here, noble metal (gold or silver) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic conductivity and plasmon resonance in the visible or near-infrared range, making them promising candidates for a wide variety of applications. Herein, we show that 2D titanium carbide, Ti3C2Tx, enhances Raman signal from organic dyes on a substrate and in solution. As a proof of concept, MXene SERS substrates were manufactured by spray-coating and used to detect several common dyes, with calculated enhancement factors reaching ~106. Titanium carbide MXene demonstrates SERS effect in aqueous colloidal solutions, suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance positively charged molecules.

  12. Two-dimensional N=(2,2) lattice gauge theories with matter in higher representations

    International Nuclear Information System (INIS)

    Joseph, Anosh

    2014-06-01

    We construct two-dimensional N=(2,2) supersymmetric gauge theories on a Euclidean spacetime lattice with matter in the two-index symmetric and anti-symmetric representations of SU(N c ) color group. These lattice theories preserve a subset of the supercharges exact at finite lattice spacing. The method of topological twisting is used to construct such theories in the continuum and then the geometric discretization scheme is used to formulate them on the lattice. The lattice theories obtained this way are gauge-invariant, free from fermion doubling problem and exact supersymmetric at finite lattice spacing. We hope that these lattice constructions further motivate the nonperturbative explorations of models inspired by technicolor, orbifolding and orientifolding in string theories and the Corrigan-Ramond limit.

  13. A two-dimensional Zn coordination polymer with a three-dimensional supramolecular architecture

    Directory of Open Access Journals (Sweden)

    Fuhong Liu

    2017-10-01

    Full Text Available The title compound, poly[bis{μ2-4,4′-bis[(1,2,4-triazol-1-ylmethyl]biphenyl-κ2N4:N4′}bis(nitrato-κOzinc(II], [Zn(NO32(C18H16N62]n, is a two-dimensional zinc coordination polymer constructed from 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl units. It was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The ZnII cation is located on an inversion centre and is coordinated by two O atoms from two symmetry-related nitrate groups and four N atoms from four symmetry-related 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl ligands, forming a distorted octahedral {ZnN4O2} coordination geometry. The linear 4,4′-bis[(1H-1,2,4-triazol-1-ylmethyl]-1,1′-biphenyl ligand links two ZnII cations, generating two-dimensional layers parallel to the crystallographic (132 plane. The parallel layers are connected by C—H...O, C—H...N, C—H...π and π–π stacking interactions, resulting in a three-dimensional supramolecular architecture.

  14. Computational Search for Two-Dimensional MX2 Semiconductors with Possible High Electron Mobility at Room Temperature

    Directory of Open Access Journals (Sweden)

    Zhishuo Huang

    2016-08-01

    Full Text Available Neither of the two typical two-dimensional materials, graphene and single layer MoS 2 , are good enough for developing semiconductor logical devices. We calculated the electron mobility of 14 two-dimensional semiconductors with composition of MX 2 , where M (=Mo, W, Sn, Hf, Zr and Pt are transition metals, and Xs are S, Se and Te. We approximated the electron phonon scattering matrix by deformation potentials, within which long wave longitudinal acoustical and optical phonon scatterings were included. Piezoelectric scattering in the compounds without inversion symmetry is also taken into account. We found that out of the 14 compounds, WS 2 , PtS 2 and PtSe 2 are promising for logical devices regarding the possible high electron mobility and finite band gap. Especially, the phonon limited electron mobility in PtSe 2 reaches about 4000 cm 2 ·V - 1 ·s - 1 at room temperature, which is the highest among the compounds with an indirect bandgap of about 1.25 eV under the local density approximation. Our results can be the first guide for experiments to synthesize better two-dimensional materials for future semiconductor devices.

  15. Star formation in the inner galaxy: a far-infrared and radio study of two H2 regions

    International Nuclear Information System (INIS)

    Lester, D.F.; Dinerstein, H.L.; Werner, M.W.; Harvey, P.M.; Evans, N.J.II; Brown, R.L.

    1985-12-01

    Far-infrared and radio continuum maps have been made of the central 6' of the inner-galaxy H II regions G30.8-0.0 (in the W43 complex) and G25.4-02., along with radio and molecular line measurements at selected positions. An effort is made to understand far infrared wavelingths allow the dust temperature structures and total far infrared fluxes to be determined. Comparison of the radio and infrared maps shows a close relationship between the ionized gas and the infrared-emitting material. There is evidence that parts of G30.8 are substantially affected by extinction, even at far-infrared wavelengths. For G25.4-0.2, the radio recombination line and CO line data permit resolution of the distance ambiguity for this source. The confusion in distance determination is found to result from an extraordinary near-superposition of two bright H II regions. Using revised distances of 4.3 kpc for G26.4SE and 12 kpc for G25.4NW, that the latter, which is apparently the fainter of the two sources, is actually the more luminous. Though it is not seen on the Palomar Sky Survey, G25.4SE is easily visible in the 9532A line of S III and is mapped in this line. The ratio of total luminosity to ionizing luminosity is very similar to that of H II regions in the solar circle. Assuming a coeval population of ionizing stars, a normal initial mass function is indicated

  16. MO-C-17A-08: Evaluation of Lung Deformation Using Three Dimensional Strain Maps

    Energy Technology Data Exchange (ETDEWEB)

    Cui, T [Duke University, Durham, NC (United States); Huang, Q [Duke Unversity, Durham, NC (United States); Miller, W [University of Virginia, Charlottesville, VA (United States); Zhong, X [Siemens Healthcare, Atlanta, GA (United States); Yin, F; Cai, J [Duke University Medical Center, Durham, NC (United States)

    2014-06-15

    Purpose: To develop a systematic approach to generate three dimensional (3D) strain maps of lung using the displacement vector field (DVF) during the respiratory deformation, and to demonstrate its application in evaluating deformable image registration (DIR). Methods: A DVF based strain tensor at each voxel of interest (VOI) was calculated from the relative displacements between the VOI and each of the six nearest neighbors. The maximum and minimum stretches of a VOI can be determined by the principal strains (E{sub 1}, E{sub 2} and E{sub 3}), which are the eigenvalues and the corresponding strain tensors. Two healthy volunteers enrolled in this study under IRB-approved protocol, each was scanned using 3D Hyperpolarized He-3 tagging-MRI and 3D proton-MRI with TrueFISP sequence at the endof- inhalation (EOI) and the end-of-exhalation (EOE) phases. 3D DVFs of tagging- and proton-MRI were obtained by the direct measurements of the tagging grid trajectory and by the DIR method implemented in commercial software. Results: 3D strain maps were successfully generated for all DVFs. The principal strain E1s were calculated as 0.43±0.05 and 0.17±0.25 for tagging-MRI and proton-MRI, respectively. The large values of E{sub 1} indicate the predominant lung motion in the superior-inferior (SI) direction. Given that the DVFs from the tagging images are considered as the ground truth, the discrepancies in the DIR-based strain maps suggest the inaccuracy of the DIR algorithm. In the E{sub 1} maps of tagging-MRI for subject 1, the fissures were distinguishable by the larger values (0.49±0.02) from the adjacent tissues (0.41±0.03) due to the larger relative displacement between the lung lobes. Conclusion: We have successfully developed a methodology to generate DVF-based 3D strain maps of lung. It can potentially enable us to better understand the pulmonary biomechanics and to evaluate and improve the DIR algorithms for the lung deformation. We are currently studying more

  17. Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS2 systems

    KAUST Repository

    Cheng, Yingchun; Guo, Z. B.; Mi, W. B.; Schwingenschlö gl, Udo; Zhu, Zhiyong

    2013-01-01

    Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number

  18. A three-dimensional head-and-neck phantom for validation of multimodality deformable image registration for adaptive radiotherapy

    International Nuclear Information System (INIS)

    Singhrao, Kamal; Kirby, Neil; Pouliot, Jean

    2014-01-01

    Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage (kV) and megavoltage (MV) imaging modalities and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kV and MV imaging. The phantom opens along a sagittal midsection to reveal radiotransparent markers, which were used to characterize the phantom deformation. The deformed and undeformed phantoms were scanned with kV and MV imaging modalities. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able to represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV–kV registration, MIM produced mean and maximum errors of 1.8 and 11.5 mm, respectively. These same numbers for Velocity were 2.4 and 7.1 mm, respectively. For MV–MV, kV–MV, and kV–MC Velocity produced similar mean and maximum error values. MIM, however, produced gross errors for all three of these scenarios, with maximum errors ranging from 33.4 to 41.6 mm. Conclusions: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool

  19. Theory of the one- and two-dimensional electron gas

    International Nuclear Information System (INIS)

    Emery, V.J.

    1987-01-01

    Two topics are discussed: (1) the competition between 2k/sub F/ and 4k/sub F/ charge state waves in a one-dimensional electron gas and (2) a two-dimensional model of high T/sub c/ superconductivity in the oxides

  20. Current status of three-dimensional silicon photonic crystals operating at infrared wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    LIN,SHAWN-YU; FLEMING,JAMES G.; SIGALAS,M.M.; BISWAS,R.; HO,K.M.

    2000-05-11

    In this paper, the experimental realization and promises of three-dimensional (3D) photonic crystals in the infrared and optical wavelengths will be described. Emphasis will be placed on the development of new 3D photonic crystals, the micro- and nano-fabrication techniques, the construction of high-Q micro-cavities and the creation of 3D waveguides.

  1. Two-Dimensional Materials for Sensing: Graphene and Beyond

    Directory of Open Access Journals (Sweden)

    Seba Sara Varghese

    2015-09-01

    Full Text Available Two-dimensional materials have attracted great scientific attention due to their unusual and fascinating properties for use in electronics, spintronics, photovoltaics, medicine, composites, etc. Graphene, transition metal dichalcogenides such as MoS2, phosphorene, etc., which belong to the family of two-dimensional materials, have shown great promise for gas sensing applications due to their high surface-to-volume ratio, low noise and sensitivity of electronic properties to the changes in the surroundings. Two-dimensional nanostructured semiconducting metal oxide based gas sensors have also been recognized as successful gas detection devices. This review aims to provide the latest advancements in the field of gas sensors based on various two-dimensional materials with the main focus on sensor performance metrics such as sensitivity, specificity, detection limit, response time, and reversibility. Both experimental and theoretical studies on the gas sensing properties of graphene and other two-dimensional materials beyond graphene are also discussed. The article concludes with the current challenges and future prospects for two-dimensional materials in gas sensor applications.

  2. A two-dimensional Zn coordination polymer with a three-dimensional supra-molecular architecture.

    Science.gov (United States)

    Liu, Fuhong; Ding, Yan; Li, Qiuyu; Zhang, Liping

    2017-10-01

    The title compound, poly[bis-{μ 2 -4,4'-bis-[(1,2,4-triazol-1-yl)meth-yl]biphenyl-κ 2 N 4 : N 4' }bis-(nitrato-κ O )zinc(II)], [Zn(NO 3 ) 2 (C 18 H 16 N 6 ) 2 ] n , is a two-dimensional zinc coordination polymer constructed from 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl units. It was synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Zn II cation is located on an inversion centre and is coordinated by two O atoms from two symmetry-related nitrate groups and four N atoms from four symmetry-related 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl ligands, forming a distorted octa-hedral {ZnN 4 O 2 } coordination geometry. The linear 4,4'-bis-[(1 H -1,2,4-triazol-1-yl)meth-yl]-1,1'-biphenyl ligand links two Zn II cations, generating two-dimensional layers parallel to the crystallographic (132) plane. The parallel layers are connected by C-H⋯O, C-H⋯N, C-H⋯π and π-π stacking inter-actions, resulting in a three-dimensional supra-molecular architecture.

  3. Solution-Based Processing and Applications of Two-Dimensional Heterostructures

    Science.gov (United States)

    Hersam, Mark

    Two-dimensional materials have emerged as promising candidates for next-generation electronics and optoelectronics, but advances in scalable nanomanufacturing are required to exploit this potential in real-world technology. This talk will explore methods for improving the uniformity of solution-processed two-dimensional materials with an eye toward realizing dispersions and inks that can be deposited into large-area thin-films. In particular, density gradient ultracentrifugation allows the solution-based isolation of graphene, boron nitride, montmorillonite, and transition metal dichalcogenides (e.g., MoS2, WS2, ReS2, MoSe2, WSe2) with homogeneous thickness down to the atomically thin limit. Similarly, two-dimensional black phosphorus is isolated in organic solvents or deoxygenated aqueous surfactant solutions with the resulting phosphorene nanosheets showing field-effect transistor mobilities and on/off ratios that are comparable to micromechanically exfoliated flakes. By adding cellulosic polymer stabilizers to these dispersions, the rheological properties can be tuned by orders of magnitude, thereby enabling two-dimensional material inks that are compatible with a range of additive manufacturing methods including inkjet, gravure, screen, and 3D printing. The resulting solution-processed two-dimensional heterostructures show promise in several device applications including photodiodes, anti-ambipolar transistors, gate-tunable memristors, and heterojunction photovoltaics.

  4. Coherent control of D2/H2 dissociative ionization by a mid-infrared two-color laser field

    International Nuclear Information System (INIS)

    Wanie, Vincent; Ibrahim, Heide; Beaulieu, Samuel; Thiré, Nicolas; Schmidt, Bruno E; Légaré, François; Deng, Yunpei; Alnaser, Ali S; Litvinyuk, Igor V; Tong, Xiao-Min

    2016-01-01

    Steering the electrons during an ultrafast photo-induced process in a molecule influences the chemical behavior of the system, opening the door to the control of photochemical reactions and photobiological processes. Electrons can be efficiently localized using a strong laser field with a well-designed temporal shape of the electric component. Consequently, many experiments have been performed with laser sources in the near-infrared region (800 nm) in the interest of studying and enhancing the electron localization. However, due to its limited accessibility, the mid-infrared (MIR) range has barely been investigated, although it allows to efficiently control small molecules and even more complex systems. To push further the manipulation of basic chemical mechanisms, we used a MIR two-color (1800 and 900 nm) laser field to ionize H 2 and D 2 molecules and to steer the remaining electron during the photo-induced dissociation. The study of this prototype reaction led to the simultaneous control of four fragmentation channels. The results are well reproduced by a theoretical model solving the time-dependent Schrödinger equation for the molecular ion, identifying the involved dissociation mechanisms. By varying the relative phase between the two colors, asymmetries (i.e., electron localization selectivity) of up to 65% were obtained, corresponding to enhanced or equivalent levels of control compared to previous experiments. Experimentally easier to implement, the use of a two-color laser field leads to a better electron localization than carrier-envelope phase stabilized pulses and applying the technique in the MIR range reveals more dissociation channels than at 800 nm. (paper)

  5. Solution of the two-dimensional spectral factorization problem

    Science.gov (United States)

    Lawton, W. M.

    1985-01-01

    An approximation theorem is proven which solves a classic problem in two-dimensional (2-D) filter theory. The theorem shows that any continuous two-dimensional spectrum can be uniformly approximated by the squared modulus of a recursively stable finite trigonometric polynomial supported on a nonsymmetric half-plane.

  6. Two-dimensional effects in nonlinear Kronig-Penney models

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Christiansen, Peter Leth; Rasmussen, Kim

    1997-01-01

    An analysis of two-dimensional (2D) effects in the nonlinear Kronig-Penney model is presented. We establish an effective one-dimensional description of the 2D effects, resulting in a set of pseudodifferential equations. The stationary states of the 2D system and their stability is studied...

  7. Complex Quasi-Two-Dimensional Crystalline Order Embedded in VO2 and Other Crystals

    Science.gov (United States)

    Lovorn, Timothy; Sarker, Sanjoy K.

    2017-07-01

    Metal oxides such as VO2 undergo structural transitions to low-symmetry phases characterized by intricate crystalline order, accompanied by rich electronic behavior. We derive a minimal ionic Hamiltonian based on symmetry and local energetics which describes structural transitions involving all four observed phases, in the correct order. An exact analysis shows that complexity results from the symmetry-induced constraints of the parent phase, which forces ionic displacements to form multiple interpenetrating groups using low-dimensional pathways and distant neighbors. Displacements within each group exhibit independent, quasi-two-dimensional order, which is frustrated and fragile. This selective ordering mechanism is not restricted to VO2 : it applies to other oxides that show similar complex order.

  8. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  9. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  10. Two-dimensional nonlinear equations of supersymmetric gauge theories

    International Nuclear Information System (INIS)

    Savel'ev, M.V.

    1985-01-01

    Supersymmetric generalization of two-dimensional nonlinear dynamical equations of gauge theories is presented. The nontrivial dynamics of a physical system in the supersymmetry and supergravity theories for (2+2)-dimensions is described by the integrable embeddings of Vsub(2/2) superspace into the flat enveloping superspace Rsub(N/M), supplied with the structure of a Lie superalgebra. An equation is derived which describes a supersymmetric generalization of the two-dimensional Toda lattice. It contains both super-Liouville and Sinh-Gordon equations

  11. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

    Science.gov (United States)

    Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

    2013-10-21

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

  12. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S. [Department of Chemistry, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Long, Phillip D.; Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, The University of Chicago, Chicago, Illinois 60637 (United States)

    2013-10-21

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

  13. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

    International Nuclear Information System (INIS)

    Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S.; Long, Phillip D.; Dahlberg, Peter D.

    2013-01-01

    Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex

  14. Three-dimensional tokamak equilibria and stellarators with two-dimensional magnetic symmetry

    International Nuclear Information System (INIS)

    Garabedian, P.R.

    1997-01-01

    Three-dimensional computer codes have been developed to simulate equilibrium, stability and transport in tokamaks and stellarators. Bifurcated solutions of the tokamak problem suggest that three-dimensional effects may be more important than has generally been thought. Extensive calculations have led to the discovery of a stellarator configuration with just two field periods and with aspect ratio 3.2 that has a magnetic field spectrum B mn with toroidal symmetry. Numerical studies of equilibrium, stability and transport for this new device, called the Modular Helias-like Heliac 2 (MHH2), will be presented. (author)

  15. Two-dimensional condensation of physi-sorbed methane on layer-like halides

    International Nuclear Information System (INIS)

    Nardon, Yves

    1972-01-01

    Two-dimensional condensation of methane in physi-sorbed layers has been studied from sets of stepped isotherms of methane on the cleavage plane of layer-like halides (FeCl 2 , CdCl 2 , NiBr 2 , CdBr 2 , FeI 2 , CaI 2 , CaI 2 and PbI 2 ) in most cases prepared by sublimation in a rapid current of inert gas. The vertical parts of the steps of adsorption isotherms correspond to the formation of successive monomolecular layers by two-dimensional condensation. Thermodynamic analysis of experimental results, has mainly emphasized the important effect of the potential relief of adsorbent surfaces, on both the structure of the physi-sorbed layers and the two-dimensional critical temperature. From its entropy, we conclude that the first layer is a (111) plane of f.c.c.: methane which becomes more loosely packed as the dimensional compatibility of the lattices of the adsorbent and adsorbate becomes poorer. Experimental values of the two-dimensional critical temperatures in the first, second and third layers have been determined, and interpreted on the following basis. An expansion of the layer induces a lowering of the two-dimensional critical temperature by decreasing the lateral interaction energy, while a localisation of the adsorbed molecules in potential wells, when possible, induces a rise of the two-dimensional critical temperature. (author) [fr

  16. Thermodynamic analysis of application of organic Rankine cycle for heat recovery from an integrated DIR-MCFC with pre-reformer

    International Nuclear Information System (INIS)

    Vatani, Ali; Khazaeli, Ali; Roshandel, Ramin; Panjeshahi, Mohammad Hassan

    2013-01-01

    Highlights: ► Using an integrated pre-reformer before feeding a DIR-MCFC is proposed. ► An ORC with different working fluid is used for waste heat recovery from the proposed plant. ► Performance of compound system is evaluated by thermodynamic analysis. ► An improvement on simultaneously heat integration between the units and waste heat recovery is performed. ► Overall energy and exergy efficiencies are found to be 60.45% and 57.75%. - Abstract: This work deals with waste heat recovery from a proposed direct internal reforming molten carbonate fuel cell (DIR-MCFC), including an integrated pre-reformer. In this regard, some advantages are attainable over exhaust gas recycling. For instance, due to low temperature in the pre-reformer, carbon deposition and coke formation resulting from higher hydrocarbons can be eliminated. In this study, the cathode outlet provides the heat requirement for the pre-reforming process. After partial heat recovery from the cathode outlet, the stream still has a considerable energy and exergy (352.55 °C and 83.687 kW respectively). This study investigates waste heat recovery from the proposed DIR-MCFC, using an organic Rankine cycle (ORC) with two different configurations. In the first case, the cathode outlet provides the heat requirement for the pre-reforming process; then, it enters the heat recovery vapor generator of the organic Rankine cycle. In the second case, the cathode outlet is split into two streams for using in an ORC and supplying the pre-reforming process required heat. Several substances are selected as working fluids in order to compare their performance in the waste heat recovery system. The overall results at optimum conditions indicate that the energy and exergy efficiencies of the compound system are increased and its exergy loss is decreased with cathode splitting for all substances (1.1% average over all fluids). It is concluded that cathode splitting has a significant impact on the substances which

  17. Multiple resonant absorber with prism-incorporated graphene and one-dimensional photonic crystals in the visible and near-infrared spectral range

    Science.gov (United States)

    Zou, X. J.; Zheng, G. G.; Chen, Y. Y.; Xu, L. H.; Lai, M.

    2018-04-01

    A multi-band absorber constructed from prism-incorporated one-dimensional photonic crystal (1D-PhC) containing graphene defects is achieved theoretically in the visible and near-infrared (vis-NIR) spectral range. By means of the transfer matrix method (TMM), the effect of structural parameters on the optical response of the structure has been investigated. It is possible to achieve multi-peak and complete optical absorption. The simulations reveal that the light intensity is enhanced at the graphene plane, and the resonant wavelength and the absorption intensity can also be tuned by tilting the incidence angle of the impinging light. In particular, multiple graphene sheets are embedded in the arrays, without any demand of manufacture process to cut them into periodic patterns. The proposed concept can be extended to other two-dimensional (2D) materials and engineered for promising applications, including selective or multiplex filters, multiple channel sensors, and photodetectors.

  18. Two-dimensional metamaterial optics

    International Nuclear Information System (INIS)

    Smolyaninov, I I

    2010-01-01

    While three-dimensional photonic metamaterials are difficult to fabricate, many new concepts and ideas in the metamaterial optics can be realized in two spatial dimensions using planar optics of surface plasmon polaritons. In this paper we review recent progress in this direction. Two-dimensional photonic crystals, hyperbolic metamaterials, and plasmonic focusing devices are demonstrated and used in novel microscopy and waveguiding schemes

  19. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-01-01

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed

  20. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Hiroaki; Sul, Soohwan [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States); Ge, Nien-Hui, E-mail: nhge@uci.edu [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States)

    2013-08-30

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  1. Digital Review of Asia Pacific (DirAP) - Phase II | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'honorable Chrystia Freeland, ministre du Commerce international, a annoncé le lancement d'un nouveau projet financé par le Centre de recherches pour le ... Le Panorama numérique de l'Asie-Pacifique (Digital Review of Asia Pacific ou DirAP) a pour objet de produire des connaissances et de la documentation ...

  2. Exploring two-dimensional electron gases with two-dimensional Fourier transform spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Paul, J.; Dey, P.; Karaiskaj, D., E-mail: karaiskaj@usf.edu [Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620 (United States); Tokumoto, T.; Hilton, D. J. [Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294 (United States); Reno, J. L. [CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2014-10-07

    The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells of 12 nm and 18 nm thickness and in-well carrier concentration of ∼4 × 10{sup 11} cm{sup −2} was carefully measured using spectrally resolved four-wave mixing (FWM) and two-dimensional Fourier transform (2DFT) spectroscopy. Although the absorption at the Fermi edge is broad at this doping level, the spectrally resolved FWM shows narrow resonances. Two peaks are observed separated by the heavy hole/light hole energy splitting. Temperature dependent “rephasing” (S{sub 1}) 2DFT spectra show a rapid linear increase of the homogeneous linewidth with temperature. The dephasing rate increases faster with temperature in the narrower 12 nm quantum well, likely due to an increased carrier-phonon scattering rate. The S{sub 1} 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations. Distinct 2DFT lineshapes were observed for co-linear and cross-linear polarizations, suggesting the existence of polarization dependent contributions. The “two-quantum coherence” (S{sub 3}) 2DFT spectra for the 12 nm quantum well show a single peak for both co-linear and co-circular polarizations.

  3. Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation

    Science.gov (United States)

    2010-01-01

    Background CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers. Methods In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. Results The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p 0.90, p < 0.001). Of the 16 subjects tested; eight subjects reported pricking pain in the hairy skin following a stimulus of 0.6 J/cm2 (5 W, 0.12 s, d1/e2 = 11.4 mm) only two reported pain to glabrous skin stimulation using the same stimulus intensity. The temperature at the epidermal-dermal junction (depth 50 μm in hairy and depth 133 μm in glabrous skin) was estimated to 46°C for hairy skin stimulation and 39°C for glabrous skin stimulation. Conclusions As compared to previous one dimensional heat distribution models, the current two dimensional model provides new possibilities for detailed studies regarding CO2 laser stimulation intensity, temperature levels and nociceptor activation. PMID:21059226

  4. High Y-chromosomal differentiation among ethnic groups of Dir and Swat districts, Pakistan

    DEFF Research Database (Denmark)

    Ullah, Inam; Olofsson, Jill K.; Margaryan, Ashot

    2017-01-01

    The ethnic groups that inhabit the mountainous Dir and Swat districts of northern Pakistan are marked by high levels of cultural and phenotypic diversity. To obtain knowledge of the extent of genetic diversity in this region, we investigated Y-chromosomal diversity in five population samples repr...

  5. Two-dimensional membranes in motion

    NARCIS (Netherlands)

    Davidovikj, D.

    2018-01-01

    This thesis revolves around nanomechanical membranes made of suspended two - dimensional materials. Chapters 1-3 give an introduction to the field of 2D-based nanomechanical devices together with an overview of the underlying physics and the measurementtools used in subsequent chapters. The research

  6. Procedures for two-dimensional electrophoresis of proteins

    Energy Technology Data Exchange (ETDEWEB)

    Tollaksen, S.L.; Giometti, C.S.

    1996-10-01

    High-resolution two-dimensional gel electrophoresis (2DE) of proteins, using isoelectric focusing in the first dimension and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) in the second, was first described in 1975. In the 20 years since those publications, numerous modifications of the original method have evolved. The ISO-DALT system of 2DE is a high-throughput approach that has stood the test of time. The problem of casting many isoelectric focusing gels and SDS-PAGE slab gels (up to 20) in a reproducible manner has been solved by the use of the techniques and equipment described in this manual. The ISO-DALT system of two-dimensional gel electrophoresis originated in the late 1970s and has been modified many times to improve its high-resolution, high-throughput capabilities. This report provides the detailed procedures used with the current ISO-DALT system to prepare, run, stain, and photograph two-dimensional gels for protein analysis.

  7. Two-dimensional radiative transfer for the retrieval of limb emission measurements in the martian atmosphere

    Science.gov (United States)

    Kleinböhl, Armin; Friedson, A. James; Schofield, John T.

    2017-01-01

    The remote sounding of infrared emission from planetary atmospheres using limb-viewing geometry is a powerful technique for deriving vertical profiles of structure and composition on a global scale. Compared with nadir viewing, limb geometry provides enhanced vertical resolution and greater sensitivity to atmospheric constituents. However, standard limb profile retrieval techniques assume spherical symmetry and are vulnerable to biases produced by horizontal gradients in atmospheric parameters. We present a scheme for the correction of horizontal gradients in profile retrievals from limb observations of the martian atmosphere. It characterizes horizontal gradients in temperature, pressure, and aerosol extinction along the line-of-sight of a limb view through neighboring measurements, and represents these gradients by means of two-dimensional radiative transfer in the forward model of the retrieval. The scheme is applied to limb emission measurements from the Mars Climate Sounder instrument on Mars Reconnaissance Orbiter. Retrieval simulations using data from numerical models indicate that biases of up to 10 K in the winter polar region, obtained with standard retrievals using spherical symmetry, are reduced to about 2 K in most locations by the retrieval with two-dimensional radiative transfer. Retrievals from Mars atmospheric measurements suggest that the two-dimensional radiative transfer greatly reduces biases in temperature and aerosol opacity caused by observational geometry, predominantly in the polar winter regions.

  8. An integrable (2+1)-dimensional Toda equation with two discrete variables

    International Nuclear Information System (INIS)

    Cao Cewen; Cao Jianli

    2007-01-01

    An integrable (2+1)-dimensional Toda equation with two discrete variables is presented from the compatible condition of a Lax triad composed of the ZS-AKNS (Zakharov, Shabat; Ablowitz, Kaup, Newell, Segur) eigenvalue problem and two discrete spectral problems. Through the nonlinearization technique, the Lax triad is transformed into a Hamiltonian system and two symplectic maps, respectively, which are integrable in the Liouville sense, sharing the same set of integrals, functionally independent and involutive with each other. In the Jacobi variety of the associated algebraic curve, both the continuous and the discrete flows are straightened out by the Abel-Jacobi coordinates, and are integrated by quadratures. An explicit algebraic-geometric solution in the original variable is obtained by the Riemann-Jacobi inversion

  9. Orbital order and effective mass enhancement in t2 g two-dimensional electron gases

    Science.gov (United States)

    Tolsma, John; Principi, Alessandro; Polini, Marco; MacDonald, Allan

    2015-03-01

    It is now possible to prepare d-electron two-dimensional electron gas systems that are confined near oxide heterojunctions and contain t2 g electrons with a density much smaller than one electron per metal atom. I will discuss a generic model that captures all qualitative features of electron-electron interaction physics in t2 g two-dimensional electron gas systems, and the use of a GW approximation to explore t2 g quasiparticle properties in this new context. t2 g electron gases contain a high density isotropic light mass xy component and low-density xz and yz anisotropic components with light and heavy masses in orthogonal directions. The high density light mass band screens interactions within the heavy bands. As a result the wave vector dependence of the self-energy is reduced and the effective mass is increased. When the density in the heavy bands is low, the difference in anisotropy between the two heavy bands favors orbital order. When orbital order does not occur, interactions still reshape the heavy-band Fermi surfaces. I will discuss these results in the context of recently reported magnetotransport experiments.

  10. New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

    International Nuclear Information System (INIS)

    Xiong, Kecai; Liu, Wei; Teat, Simon J.; An, Litao; Wang, Hao; Emge, Thomas J.; Li, Jing

    2015-01-01

    Two new hybrid lead halides (H 2 BDA)[PbI 4 ] (1) (H 2 BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI 3 ] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations

  11. New hybrid lead iodides: From one-dimensional chain to two-dimensional layered perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Kecai; Liu, Wei [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Teat, Simon J. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); An, Litao; Wang, Hao; Emge, Thomas J. [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States); Li, Jing, E-mail: jingli@rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854 (United States)

    2015-10-15

    Two new hybrid lead halides (H{sub 2}BDA)[PbI{sub 4}] (1) (H{sub 2}BDA=1,4-butanediammonium dication) and (HNPEIM)[PbI{sub 3}] (2) (HNPEIM=N-​phenyl-ethanimidamidine cation) have been synthesized and structurally characterized. X-ray diffraction analyses reveal that compound 1 features a two-dimensional corner-sharing perovskite layer whereas compound 2 contains one-dimensional edge-sharing double chains. The N-​phenyl-ethanimidamidine cation within compound 2 was generated in-situ under solvothermal conditions. The optical absorption spectra collected at room temperature suggest that both compounds are semiconductors having direct band gaps, with estimated values of 2.64 and 2.73 eV for 1 and 2, respectively. Results from the density functional theory (DFT) calculations are consistent with the experimental data. Density of states (DOS) analysis reveals that in both compounds 1 and 2, the energy states in the valence band maximum region are iodine 5p atomic orbitals with a small contribution from lead 6s, while in the region of conduction band minimum, the major contributions are from the inorganic (Pb 6p atomic orbitals) and organic components (C and N 2p atomic orbitals) in compound 1 and 2, respectively. - Graphical abstract: Two new hybrid lead halides built on one-dimensional edge-sharing double chains and two-dimensional corner-sharing perovskite layers are synthesized and their structural and electronic properties are analyzed. - Highlights: • Two new hybrid lead iodides are designed, synthesized, and characterized. • They are closely related to, but different from, perovskite structures. • The electronic properties of both compounds are analyzed by DFT calculations.

  12. Evidence for Intramolecular Antiparallel Beta-Sheet Structure in Alpha-Synuclein Fibrils from a Combination of Two-Dimensional Infrared Spectroscopy and Atomic Force Microscopy

    Science.gov (United States)

    Roeters, Steven J.; Iyer, Aditya; Pletikapić, Galja; Kogan, Vladimir; Subramaniam, Vinod; Woutersen, Sander

    2017-01-01

    The aggregation of the intrinsically disordered protein alpha-synuclein (αS) into amyloid fibrils is thought to play a central role in the pathology of Parkinson’s disease. Using a combination of techniques (AFM, UV-CD, XRD, and amide-I 1D- and 2D-IR spectroscopy) we show that the structure of αS fibrils varies as a function of ionic strength: fibrils aggregated in low ionic-strength buffers ([NaCl] ≤ 25 mM) have a significantly different structure than fibrils grown in higher ionic-strength buffers. The observations for fibrils aggregated in low-salt buffers are consistent with an extended conformation of αS molecules, forming hydrogen-bonded intermolecular β-sheets that are loosely packed in a parallel fashion. For fibrils aggregated in high-salt buffers (including those prepared in buffers with a physiological salt concentration) the measurements are consistent with αS molecules in a more tightly-packed, antiparallel intramolecular conformation, and suggest a structure characterized by two twisting stacks of approximately five hydrogen-bonded intermolecular β-sheets each. We find evidence that the high-frequency peak in the amide-I spectrum of αS fibrils involves a normal mode that differs fundamentally from the canonical high-frequency antiparallel β-sheet mode. The high sensitivity of the fibril structure to the ionic strength might form the basis of differences in αS-related pathologies.

  13. Edge Epitaxy of Two-dimensional MoSe2 and MoS2 Nanosheets on One-dimensional Nanowires

    KAUST Repository

    Chen, Junze; Wu, Xue-Jun; Gong, Yue; Zhu, Yihan; Yang, Zhenzhong; Li, Bing; Lu, Qipeng; Yu, Yifu; Han, Shikui; Zhang, Zhicheng; Zong, Yun; Han, Yu; Gu, Lin; Zhang, Hua

    2017-01-01

    the longitudinal direction of one-dimensional (1D) Cu2-xS nanowires (NWs) in an epitaxial manner. The obtained Cu2-xS-TMD heterostructures with tunable loading amount and lateral size of TMD NSs are achieved by the consecutive growth of TMD NSs on Cu2-xS NWs

  14. Two dimensional solid state NMR

    International Nuclear Information System (INIS)

    Kentgens, A.P.M.

    1987-01-01

    This thesis illustrates, by discussing some existing and newly developed 2D solid state experiments, that two-dimensional NMR of solids is a useful and important extension of NMR techniques. Chapter 1 gives an overview of spin interactions and averaging techniques important in solid state NMR. As 2D NMR is already an established technique in solutions, only the basics of two dimensional NMR are presented in chapter 2, with an emphasis on the aspects important for solid spectra. The following chapters discuss the theoretical background and applications of specific 2D solid state experiments. An application of 2D-J resolved NMR, analogous to J-resolved spectroscopy in solutions, to natural rubber is given in chapter 3. In chapter 4 the anisotropic chemical shift is mapped out against the heteronuclear dipolar interaction to obtain information about the orientation of the shielding tensor in poly-(oxymethylene). Chapter 5 concentrates on the study of super-slow molecular motions in polymers using a variant of the 2D exchange experiment developed by us. Finally chapter 6 discusses a new experiment, 2D nutation NMR, which makes it possible to study the quadrupole interaction of half-integer spins. 230 refs.; 48 figs.; 8 tabs

  15. Critical Behaviour of a Two-Dimensional Random Antiferromagnet

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.

    1976-01-01

    A neutron scattering study of the order parameter, correlation length and staggered susceptibility of the two-dimensional random antiferromagnet Rb2Mn0.5Ni0.5F4 is reported. The system is found to exhibit a well-defined phase transition with critical exponents identical to those of the isomorphou...... pure materials K2NiF4 and K2MnF4. Thus, in these systems, which have the asymptotic critical behaviour of the two-dimensional Ising model, randomness has no measurable effect on the phase-transition behaviour....

  16. Silicon isotope separation utilizing infrared multiphoton dissociation of Si2F6 irradiated with two-color CO2 laser light

    International Nuclear Information System (INIS)

    Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi; Arai, Shigeyoshi

    2002-01-01

    Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si 2 F 6 irradiated with two-color CO 2 laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of 28 Si was obtained at 49.63% dissociation of Si 2 F 6 after the simultaneous irradiation of 200 pulses with 966.23 cm -1 photons (0.084 J/cm 2 ) and 954.55 cm -1 photons (0.658 J/cm 2 ), while 2000 pulses were needed to obtain 99.35% of 28 Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm -1 (0.97 J/cm 2 ). (author)

  17. Analysis of Different Classification Techniques for Two-Class Functional Near-Infrared Spectroscopy-Based Brain-Computer Interface

    Directory of Open Access Journals (Sweden)

    Noman Naseer

    2016-01-01

    Full Text Available We analyse and compare the classification accuracies of six different classifiers for a two-class mental task (mental arithmetic and rest using functional near-infrared spectroscopy (fNIRS signals. The signals of the mental arithmetic and rest tasks from the prefrontal cortex region of the brain for seven healthy subjects were acquired using a multichannel continuous-wave imaging system. After removal of the physiological noises, six features were extracted from the oxygenated hemoglobin (HbO signals. Two- and three-dimensional combinations of those features were used for classification of mental tasks. In the classification, six different modalities, linear discriminant analysis (LDA, quadratic discriminant analysis (QDA, k-nearest neighbour (kNN, the Naïve Bayes approach, support vector machine (SVM, and artificial neural networks (ANN, were utilized. With these classifiers, the average classification accuracies among the seven subjects for the 2- and 3-dimensional combinations of features were 71.6, 90.0, 69.7, 89.8, 89.5, and 91.4% and 79.6, 95.2, 64.5, 94.8, 95.2, and 96.3%, respectively. ANN showed the maximum classification accuracies: 91.4 and 96.3%. In order to validate the results, a statistical significance test was performed, which confirmed that the p values were statistically significant relative to all of the other classifiers (p < 0.005 using HbO signals.

  18. Metallic few-layered VS2 ultrathin nanosheets: high two-dimensional conductivity for in-plane supercapacitors.

    Science.gov (United States)

    Feng, Jun; Sun, Xu; Wu, Changzheng; Peng, Lele; Lin, Chenwen; Hu, Shuanglin; Yang, Jinlong; Xie, Yi

    2011-11-09

    With the rapid development of portable electronics, such as e-paper and other flexible devices, practical power sources with ultrathin geometries become an important prerequisite, in which supercapacitors with in-plane configurations are recently emerging as a favorable and competitive candidate. As is known, electrode materials with two-dimensional (2D) permeable channels, high-conductivity structural scaffolds, and high specific surface areas are the indispensible requirements for the development of in-plane supercapacitors with superior performance, while it is difficult for the presently available inorganic materials to make the best in all aspects. In this sense, vanadium disulfide (VS(2)) presents an ideal material platform due to its synergic properties of metallic nature and exfoliative characteristic brought by the conducting S-V-S layers stacked up by weak van der Waals interlayer interactions, offering great potential as high-performance in-plane supercapacitor electrodes. Herein, we developed a unique ammonia-assisted strategy to exfoliate bulk VS(2) flakes into ultrathin VS(2) nanosheets stacked with less than five S-V-S single layers, representing a brand new two-dimensional material having metallic behavior aside from graphene. Moreover, highly conductive VS(2) thin films were successfully assembled for constructing the electrodes of in-plane supercapacitors. As is expected, a specific capacitance of 4760 μF/cm(2) was realized here in a 150 nm in-plane configuration, of which no obvious degradation was observed even after 1000 charge/discharge cycles, offering as a new in-plane supercapacitor with high performance based on quasi-two-dimensional materials.

  19. Two Dimensional X-Ray Diffraction (2D-XRD) studies on Olivine of U.S.A

    International Nuclear Information System (INIS)

    Jabeen, S.; Raza, S.M.; Ahmed, M.A.; Zai, M.Y.; Elacher, K.

    2011-01-01

    The Olivine (Mg, Fe) 2SiO/sub 4/ of USA has been studied with two dimensional X-ray diffractometer (D8 discover with GADDS). The two distinct phases of orthorhombic structure, one with Mg/sub 8/[Fe/sub 2/SiO/sub 4/] and the other with Mg/sub 2/SiO/sub 4/ is observed. We also observed phase transitions due to presence of iron and Silicon preferably the structural change of Mg/sub 8/[Fe/sub 2/SiO/sub 4/] from orthorhombic to spinel like (spinel chord) structure. Magnesium ions in Mg/sub 8/[Fe/sub 2/SiO/sub 4/] shuffle, arrange at the five vertices of a pentagon and the remaining three at the central but with displaced position from the plane of the pentagon, Thus resulting into a three dimensional spinel chord like structure. We evidenced the same from diverse orientations of phase peaks and indeed from Kossel lines. (author)

  20. Photodetectors based on junctions of two-dimensional transition metal dichalcogenides

    International Nuclear Information System (INIS)

    Wei Xia; Yan Fa-Guang; Shen Chao; Lv Quan-Shan; Wang Kai-You

    2017-01-01

    Transition metal dichalcogenides (TMDCs) have gained considerable attention because of their novel properties and great potential applications. The flakes of TMDCs not only have great light absorption from visible to near infrared, but also can be stacked together regardless of lattice mismatch like other two-dimensional (2D) materials. Along with the studies on intrinsic properties of TMDCs, the junctions based on TMDCs become more and more important in applications of photodetection. The junctions have shown many exciting possibilities to fully combine the advantages of TMDCs, other 2D materials, conventional and organic semiconductors together. Early studies have greatly enriched the application of TMDCs in photodetection. In this review, we investigate the efforts in photodetectors based on the junctions of TMDCs and analyze the properties of those photodetectors. Homojunctions based on TMDCs can be made by surface chemical doping, elemental doping and electrostatic gating. Heterojunction formed between TMDCs/2D materials, TMDCs/conventional semiconductors and TMDCs/organic semiconductor also deserve more attentions. We also compare the advantages and disadvantages of different junctions, and then give the prospects for the development of junctions based on TMDCs. (topical reviews)

  1. Late gadolinium enhancement cardiac imaging on a 3T scanner with parallel RF transmission technique: prospective comparison of 3D-PSIR and 3D-IR

    International Nuclear Information System (INIS)

    Schultz, Anthony; Caspar, Thibault; Schaeffer, Mickael; Labani, Aissam; Jeung, Mi-Young; El Ghannudi, Soraya; Roy, Catherine; Ohana, Mickael

    2016-01-01

    To qualitatively and quantitatively compare different late gadolinium enhancement (LGE) sequences acquired at 3T with a parallel RF transmission technique. One hundred and sixty participants prospectively enrolled underwent a 3T cardiac MRI with 3 different LGE sequences: 3D Phase-Sensitive Inversion-Recovery (3D-PSIR) acquired 5 minutes after injection, 3D Inversion-Recovery (3D-IR) at 9 minutes and 3D-PSIR at 13 minutes. All LGE-positive patients were qualitatively evaluated both independently and blindly by two radiologists using a 4-level scale, and quantitatively assessed with measurement of contrast-to-noise ratio and LGE maximal surface. Statistical analyses were calculated under a Bayesian paradigm using MCMC methods. Fifty patients (70 % men, 56yo ± 19) exhibited LGE (62 % were post-ischemic, 30 % related to cardiomyopathy and 8 % post-myocarditis). Early and late 3D-PSIR were superior to 3D-IR sequences (global quality, estimated coefficient IR > early-PSIR: -2.37 CI = [-3.46; -1.38], prob(coef > 0) = 0 % and late-PSIR > IR: 3.12 CI = [0.62; 4.41], prob(coef > 0) = 100 %), LGE surface estimated coefficient IR > early-PSIR: -0.09 CI = [-1.11; -0.74], prob(coef > 0) = 0 % and late-PSIR > IR: 0.96 CI = [0.77; 1.15], prob(coef > 0) = 100 %. Probabilities for late PSIR being superior to early PSIR concerning global quality and CNR were over 90 %, regardless of the aetiological subgroup. In 3T cardiac MRI acquired with parallel RF transmission technique, 3D-PSIR is qualitatively and quantitatively superior to 3D-IR. (orig.)

  2. Peak clustering in two-dimensional gas chromatography with mass spectrometric detection based on theoretical calculation of two-dimensional peak shapes: the 2DAid approach.

    Science.gov (United States)

    van Stee, Leo L P; Brinkman, Udo A Th

    2011-10-28

    A method is presented to facilitate the non-target analysis of data obtained in temperature-programmed comprehensive two-dimensional (2D) gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-ToF-MS). One main difficulty of GC×GC data analysis is that each peak is usually modulated several times and therefore appears as a series of peaks (or peaklets) in the one-dimensionally recorded data. The proposed method, 2DAid, uses basic chromatographic laws to calculate the theoretical shape of a 2D peak (a cluster of peaklets originating from the same analyte) in order to define the area in which the peaklets of each individual compound can be expected to show up. Based on analyte-identity information obtained by means of mass spectral library searching, the individual peaklets are then combined into a single 2D peak. The method is applied, amongst others, to a complex mixture containing 362 analytes. It is demonstrated that the 2D peak shapes can be accurately predicted and that clustering and further processing can reduce the final peak list to a manageable size. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Bi[NC5H3(CO2)2](OH2)xF (x=1 and 2): New one-dimensional Bi-coordination materials—Reversible hydration and topotactic decomposition to α-Bi2O3

    International Nuclear Information System (INIS)

    Jeon, Hye Rim; Lee, Dong Woo; Ok, Kang Min

    2012-01-01

    Two one-dimensional bismuth-coordination materials, Bi[NC 5 H 3 (CO 2 ) 2 ](OH 2 ) x F (x=1 and 2), have been synthesized by hydrothermal reactions using Bi 2 O 3 , 2,6-NC 5 H 3 (CO 2 H) 2 , HF, and water at 180 °C. Structures of the two materials were determined by single-crystal X-ray diffraction. Although they have different crystal structures, both Bi-organic materials shared a common structural motif, a one-dimensional chain structure consisting of Bi 3+ cations and pyridine dicarboxylate linkers. Detailed structural analyses include infrared spectroscopy, thermogravimetric analysis, and reversible hydration reactions for the coordinated water molecules were reported. Also, thermal decomposition of the rod-shaped Bi[NC 5 H 3 (CO 2 ) 2 ](OH 2 )F single crystals at 800 °C led to α-Bi 2 O 3 that maintained the same morphology of the original crystals. - Graphical abstract: Calcination of the Bi[NC 5 H 3 (CO 2 ) 2 ](OH 2 )F single crystals at 800 °C results in the α-Bi 2 O 3 rods that maintain the original morphology of the crystals. Highlights: ► Synthesis of one-dimensional chain Bi-organic frameworks. ► Reversible hydration reactions of Bi[NC 5 H 3 (CO 2 ) 2 ](OH 2 )F. ► Topotactic decomposition maintaining the same morphology of the original crystals.

  4. Two-dimensional magnetism in the triangular antiferromagnet NiGa2S4

    International Nuclear Information System (INIS)

    Nambu, Yusuke

    2013-01-01

    At sufficiently low temperatures, electron spins in normal magnets generally order into some fashion, for instance, ferromagnetic and antiferromagnetic. Geometrical frustration and/or reduced dimensionality can suppress such conventional orders, and occasionally induce unknown states of matter. This is the case for the two-dimensional (2D) triangular antiferromagnet Ni(Ga 2 S 4 , in which S=1 nickel spins do not order, instead show an exotic magnetism. We found (1) a resonant critical slowing down toward T*=8.5 K followed by a viscous spin liquid behavior, and (2) a spin-size dependent ground state. To elucidate (1), spin dynamics ranging from 10 -13 to 10 0 seconds were quantitatively explored through the experimental techniques such as inelastic neutron scattering, backscattering, neutron spin echo, ac and nonlinear susceptibilities. The finding of (2) is evidenced by impurity effects. Integer spins substituted systems such as zinc and iron ions retain a quadratic temperature dependence of the magnetic specific heat as for the parent compound. However, substitutions of half-odd integer spins, cobalt and manganese ions, eventually induce a distinct behavior, indicating an importance of integer size of spins to stabilize the 2D magnetism realized in NiGa 2 S 4 . The article gives our experimental findings and as well as some relevant theoretical scenarios. (author)

  5. Four-dimensional dose evaluation using deformable image registration in radiotherapy for liver cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hoon Jung, Sang; Min Yoon, Sang; Ho Park, Sung; Cho, Byungchul; Won Park, Jae; Jung, Jinhong; Park, Jin-hong; Hoon Kim, Jong; Do Ahn, Seung [Departments of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736 (Korea, Republic of)

    2013-01-15

    Purpose: In order to evaluate the dosimetric impact of respiratory motion on the dose delivered to the target volume and critical organs during free-breathing radiotherapy, a four-dimensional dose was evaluated using deformable image registration (DIR). Methods: Four-dimensional computed tomography (4DCT) images were acquired for 11 patients who were treated for liver cancer. Internal target volume-based treatment planning and dose calculation (3D dose) were performed using the end-exhalation phase images. The four-dimensional dose (4D dose) was calculated based on DIR of all phase images from 4DCT to the planned image. Dosimetric parameters from the 4D dose, were calculated and compared with those from the 3D dose. Results: There was no significant change of the dosimetric parameters for gross tumor volume (p > 0.05). The increase D{sub mean} and generalized equivalent uniform dose (gEUD) for liver were by 3.1%{+-} 3.3% (p= 0.003) and 2.8%{+-} 3.3% (p= 0.008), respectively, and for duodenum, they were decreased by 15.7%{+-} 11.2% (p= 0.003) and 15.1%{+-} 11.0% (p= 0.003), respectively. The D{sub max} and gEUD for stomach was decreased by 5.3%{+-} 5.8% (p= 0.003) and 9.7%{+-} 8.7% (p= 0.003), respectively. The D{sub max} and gEUD for right kidney was decreased by 11.2%{+-} 16.2% (p= 0.003) and 14.9%{+-} 16.8% (p= 0.005), respectively. For left kidney, D{sub max} and gEUD were decreased by 11.4%{+-} 11.0% (p= 0.003) and 12.8%{+-} 12.1% (p= 0.005), respectively. The NTCP values for duodenum and stomach were decreased by 8.4%{+-} 5.8% (p= 0.003) and 17.2%{+-} 13.7% (p= 0.003), respectively. Conclusions: The four-dimensional dose with a more realistic dose calculation accounting for respiratory motion revealed no significant difference in target coverage and potentially significant change in the physical and biological dosimetric parameters in normal organs during free-breathing treatment.

  6. Acoustic phonon emission by two dimensional plasmons

    International Nuclear Information System (INIS)

    Mishonov, T.M.

    1990-06-01

    Acoustic wave emission of the two dimensional plasmons in a semiconductor or superconductor microstructure is investigated by using the phenomenological deformation potential within the jellium model. The plasmons are excited by the external electromagnetic (e.m.) field. The power conversion coefficient of e.m. energy into acoustic wave energy is also estimated. It is shown, the coherent transformation has a sharp resonance at the plasmon frequency of the two dimensional electron gas (2DEG). The incoherent transformation of the e.m. energy is generated by ohmic dissipation of 2DEG. The method proposed for coherent phonon beam generation can be very effective for high mobility 2DEG and for thin superconducting layers if the plasmon frequency ω is smaller than the superconducting gap 2Δ. (author). 21 refs, 1 fig

  7. On the two-dimensional Saigo-Maeda fractional calculus asociated with two-dimensional Aleph TRANSFORM

    Directory of Open Access Journals (Sweden)

    Dinesh Kumar

    2013-11-01

    Full Text Available This paper deals with the study of two-dimensional Saigo-Maeda operators of Weyl type associated with Aleph function defined in this paper. Two theorems on these defined operators are established. Some interesting results associated with the H-functions and generalized Mittag-Leffler functions are deduced from the derived results. One dimensional analog of the derived results is also obtained.

  8. On the ground state of the two-dimensional non-ideal Bose gas

    International Nuclear Information System (INIS)

    Lozovik, Yu.E.; Yudson, V.I.

    1978-01-01

    The theory of the ground state of the two-dimensional non-ideal Bose gas is presented. The conditions for the validity of the ladder and the Bogolubov approximations are derived. These conditions ensure the existence of a Bose condensate in the ground state of two-dimensional systems. These conditions are different from the corresponding conditions for the three-dimensional case. The connection between the effective interaction and the two-dimensional scattering amplitude at some characteristic energy kappa 2 /2m (not equal to 0) is obtained (f(kappa = 0) = infinity in the two-dimensional case). (Auth.)

  9. Construction of two-dimensional quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Klimek, S.; Kondracki, W.

    1987-12-01

    We present a sketch of the construction of the functional measure for the SU(2) quantum chromodynamics with one generation of fermions in two-dimensional space-time. The method is based on a detailed analysis of Wilson loops.

  10. High-resolution two-dimensional and three-dimensional modeling of wire grid polarizers and micropolarizer arrays

    Science.gov (United States)

    Vorobiev, Dmitry; Ninkov, Zoran

    2017-11-01

    Recent advances in photolithography allowed the fabrication of high-quality wire grid polarizers for the visible and near-infrared regimes. In turn, micropolarizer arrays (MPAs) based on wire grid polarizers have been developed and used to construct compact, versatile imaging polarimeters. However, the contrast and throughput of these polarimeters are significantly worse than one might expect based on the performance of large area wire grid polarizers or MPAs, alone. We investigate the parameters that affect the performance of wire grid polarizers and MPAs, using high-resolution two-dimensional and three-dimensional (3-D) finite-difference time-domain simulations. We pay special attention to numerical errors and other challenges that arise in models of these and other subwavelength optical devices. Our tests show that simulations of these structures in the visible and near-IR begin to converge numerically when the mesh size is smaller than ˜4 nm. The performance of wire grid polarizers is very sensitive to the shape, spacing, and conductivity of the metal wires. Using 3-D simulations of micropolarizer "superpixels," we directly study the cross talk due to diffraction at the edges of each micropolarizer, which decreases the contrast of MPAs to ˜200∶1.

  11. Two-Dimensional (2D Slices Encryption-Based Security Solution for Three-Dimensional (3D Printing Industry

    Directory of Open Access Journals (Sweden)

    Giao N. Pham

    2018-05-01

    Full Text Available Nowadays, three-dimensional (3D printing technology is applied to many areas of life and changes the world based on the creation of complex structures and shapes that were not feasible in the past. But, the data of 3D printing is often attacked in the storage and transmission processes. Therefore, 3D printing must be ensured security in the manufacturing process, especially the data of 3D printing to prevent attacks from hackers. This paper presents a security solution for 3D printing based on two-dimensional (2D slices encryption. The 2D slices of 3D printing data is encrypted in the frequency domain or in the spatial domain by the secret key to generate the encrypted data of 3D printing. We implemented the proposed solution in both the frequency domain based on the Discrete Cosine Transform and the spatial domain based on geometric transform. The entire 2D slices of 3D printing data is altered and secured after the encryption process. The proposed solution is responsive to the security requirements for the secured storage and transmission. Experimental results also verified that the proposed solution is effective to 3D printing data and is independent on the format of 3D printing models. When compared to the conventional works, the security and performance of the proposed solution is also better.

  12. ALD-Developed Plasmonic Two-Dimensional Au-WO3-TiO2 Heterojunction Architectonics for Design of Photovoltaic Devices.

    Science.gov (United States)

    Karbalaei Akbari, Mohammad; Hai, Zhenyin; Wei, Zihan; Detavernier, Christophe; Solano, Eduardo; Verpoort, Francis; Zhuiykov, Serge

    2018-03-28

    Electrically responsive plasmonic devices, which benefit from the privilege of surface plasmon excited hot carries, have supported fascinating applications in the visible-light-assisted technologies. The properties of plasmonic devices can be tuned by controlling charge transfer. It can be attained by intentional architecturing of the metal-semiconductor (MS) interfaces. In this study, the wafer-scaled fabrication of two-dimensional (2D) TiO 2 semiconductors on the granular Au metal substrate is achieved using the atomic layer deposition (ALD) technique. The ALD-developed 2D MS heterojunctions exhibited substantial enhancement of the photoresponsivity and demonstrated the improvement of response time for 2D Au-TiO 2 -based plasmonic devices under visible light illumination. To circumvent the undesired dark current in the plasmonic devices, a 2D WO 3 nanofilm (∼0.7 nm) was employed as the intermediate layer on the MS interface to develop the metal-insulator-semiconductor (MIS) 2D heterostructure. As a result, 13.4% improvement of the external quantum efficiency was obtained for fabricated 2D Au-WO 3 -TiO 2 heterojunctions. The impedancometry measurements confirmed the modulation of charge transfer at the 2D MS interface using MIS architectonics. Broadband photoresponsivity from the UV to the visible light region was observed for Au-TiO 2 and Au-WO 3 -TiO 2 heterostructures, whereas near-infrared responsivity was not observed. Consequently, considering the versatile nature of the ALD technique, this approach can facilitate the architecturing and design of novel 2D MS and MIS heterojunctions for efficient plasmonic devices.

  13. On the use of band-target entropy minimization to simplify the interpretation of two-dimensional correlation spectroscopy.

    Science.gov (United States)

    Widjaja, Effendi; Tan, Boon Hong; Garland, Marc

    2006-03-01

    Two-dimensional (2D) correlation spectroscopy has been extensively applied to analyze various vibrational spectroscopic data, especially infrared and Raman. However, when it is applied to real-world experimental data, which often contains various imperfections (such as noise interference, baseline fluctuations, and band-shifting) and highly overlapping bands, many artifacts and misleading features in synchronous and asynchronous maps will emerge, and this will lead to difficulties with interpretation. Therefore, an approach that counters many artifacts and therefore leads to simplified interpretation of 2D correlation analysis is certainly useful. In the present contribution, band-target entropy minimization (BTEM) is employed as a spectral pretreatment to handle many of the artifact problems before the application of 2D correlation analysis. BTEM is employed to elucidate the pure component spectra of mixtures and their corresponding concentration profiles. Two alternate forms of analysis result. In the first, the normally vxv problem is converted to an equivalent nvxnv problem, where n represents the number of species present. In the second, the pure component spectra are transformed into simple distributions, and an equivalent and less computationally intensive nv'xnv' problem results (v'evaporation study where in situ Fourier transform infrared (FT-IR) spectroscopy is used as the analytical tool.

  14. Level crossings in complex two-dimensional potentials

    Indian Academy of Sciences (India)

    Two-dimensional P T -symmetric quantum-mechanical systems with the complex cubic potential 12 = 2 + 2 + 2 and the complex Hénon–Heiles potential HH = 2 + 2 + (2 − 3/3) are investigated. Using numerical and perturbative methods, energy spectra are obtained to high levels. Although both ...

  15. Tracking single cells in live animals using a photoconvertible near-infrared cell membrane label.

    Science.gov (United States)

    Carlson, Alicia L; Fujisaki, Joji; Wu, Juwell; Runnels, Judith M; Turcotte, Raphaël; Spencer, Joel A; Celso, Cristina Lo; Scadden, David T; Strom, Terry B; Lin, Charles P

    2013-01-01

    We describe a novel photoconversion technique to track individual cells in vivo using a commercial lipophilic membrane dye, DiR. We show that DiR exhibits a permanent fluorescence emission shift (photoconversion) after light exposure and does not reacquire the original color over time. Ratiometric imaging can be used to distinguish photoconverted from non-converted cells with high sensitivity. Combining the use of this photoconvertible dye with intravital microscopy, we tracked the division of individual hematopoietic stem/progenitor cells within the calvarium bone marrow of live mice. We also studied the peripheral differentiation of individual T cells by tracking the gain or loss of FoxP3-GFP expression, a marker of the immune suppressive function of CD4(+) T cells. With the near-infrared photoconvertible membrane dye, the entire visible spectral range is available for simultaneous use with other fluorescent proteins to monitor gene expression or to trace cell lineage commitment in vivo with high spatial and temporal resolution.

  16. Extended Polymorphism of Two-Dimensional Material

    NARCIS (Netherlands)

    Yoshida, Masaro; Ye, Jianting; Zhang, Yijin; Imai, Yasuhiko; Kimura, Shigeru; Fujiwara, Akihiko; Nishizaki, Terukazu; Kobayashi, Norio; Nakano, Masaki; Iwasa, Yoshihiro

    When controlling electronic properties of bulk materials, we usually assume that the basic crystal structure is fixed. However, in two-dimensional (2D) materials, atomic structure or to functionalize their properties. Various polymorphs can exist in transition metal dichalcogenides (TMDCs) from

  17. Two-dimensional nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Bax, A.; Lerner, L.

    1986-01-01

    Great spectral simplification can be obtained by spreading the conventional one-dimensional nuclear magnetic resonance (NMR) spectrum in two independent frequency dimensions. This so-called two-dimensional NMR spectroscopy removes spectral overlap, facilitates spectral assignment, and provides a wealth of additional information. For example, conformational information related to interproton distances is available from resonance intensities in certain types of two-dimensional experiments. Another method generates 1 H NMR spectra of a preselected fragment of the molecule, suppressing resonances from other regions and greatly simplifying spectral appearance. Two-dimensional NMR spectroscopy can also be applied to the study of 13 C and 15 N, not only providing valuable connectivity information but also improving sensitivity of 13 C and 15 N detection by up to two orders of magnitude. 45 references, 10 figures

  18. Universality of modular symmetries in two-dimensional magnetotransport

    Science.gov (United States)

    Olsen, K. S.; Limseth, H. S.; Lütken, C. A.

    2018-01-01

    We analyze experimental quantum Hall data from a wide range of different materials, including semiconducting heterojunctions, thin films, surface layers, graphene, mercury telluride, bismuth antimonide, and black phosphorus. The fact that these materials have little in common, except that charge transport is effectively two-dimensional, shows how robust and universal the quantum Hall phenomenon is. The scaling and fixed point data we analyzed appear to show that magnetotransport in two dimensions is governed by a small number of universality classes that are classified by modular symmetries, which are infinite discrete symmetries not previously seen in nature. The Hall plateaux are (infrared) stable fixed points of the scaling-flow, and quantum critical points (where the wave function is delocalized) are unstable fixed points of scaling. Modular symmetries are so rigid that they in some cases fix the global geometry of the scaling flow, and therefore predict the exact location of quantum critical points, as well as the shape of flow lines anywhere in the phase diagram. We show that most available experimental quantum Hall scaling data are in good agreement with these predictions.

  19. Black phosphorus saturable absorber for a diode-pumped passively Q-switched Er:CaF2 mid-infrared laser

    Science.gov (United States)

    Li, Chun; Liu, Jie; Guo, Zhinan; Zhang, Han; Ma, Weiwei; Wang, Jingya; Xu, Xiaodong; Su, Liangbi

    2018-01-01

    A multilayer black phosphorus, as a novel two dimensional saturable absorber, has superb saturable absorption properties for a Er:CaF2 solid-state pulse laser. The pulse laser is realized at mid-infrared region with the passively Q-switched technology by a diode-pumping. The high-quality black phosphorus saturable absorber is fabricated by liquid phase exfoliation method. The pulse laser generates the pulses operation with the pulse duration of 954.8 ns, the repetition rate of 41.93 kHz, the pulse energy of 4.25 μJ and the peak power of 4.45 W. Our work demonstrates that black phosphorus could be used as a kind of efficient mid-infrared region optical absorber for ultrafast photonics.

  20. Strain-engineered growth of two-dimensional materials.

    Science.gov (United States)

    Ahn, Geun Ho; Amani, Matin; Rasool, Haider; Lien, Der-Hsien; Mastandrea, James P; Ager Iii, Joel W; Dubey, Madan; Chrzan, Daryl C; Minor, Andrew M; Javey, Ali

    2017-09-20

    The application of strain to semiconductors allows for controlled modification of their band structure. This principle is employed for the manufacturing of devices ranging from high-performance transistors to solid-state lasers. Traditionally, strain is typically achieved via growth on lattice-mismatched substrates. For two-dimensional (2D) semiconductors, this is not feasible as they typically do not interact epitaxially with the substrate. Here, we demonstrate controlled strain engineering of 2D semiconductors during synthesis by utilizing the thermal coefficient of expansion mismatch between the substrate and semiconductor. Using WSe 2 as a model system, we demonstrate stable built-in strains ranging from 1% tensile to 0.2% compressive on substrates with different thermal coefficient of expansion. Consequently, we observe a dramatic modulation of the band structure, manifested by a strain-driven indirect-to-direct bandgap transition and brightening of the dark exciton in bilayer and monolayer WSe 2 , respectively. The growth method developed here should enable flexibility in design of more sophisticated devices based on 2D materials.Strain engineering is an essential tool for modifying local electronic properties in silicon-based electronics. Here, Ahn et al. demonstrate control of biaxial strain in two-dimensional materials based on the growth substrate, enabling more complex low-dimensional electronics.

  1. Anisotropic strain in YBa2Cu3O7-δ films analysed by deconvolution of two-dimensional intensity data

    International Nuclear Information System (INIS)

    Broetz, J.; Fuess, H.

    2001-01-01

    The influence of the instrumental resolution on two-dimensional reflection profiles of epitaxic YBa 2 Cu 3 O 7-δ films on SrTiO 3 (001) has been studied in order to investigate the strain in the superconducting films. The X-ray diffraction intensity data were obtained by two-dimensional scans in reciprocal space (q-scan). Since the reflection broadening caused by the apparatus differs for each position in reciprocal space, a highly crystalline substrate was used as a standard. Thus it was possible to measure a standard very close to the YBa 2 Cu 3 O 7-δ reflections in reciprocal space. The two-dimensional deconvolution of reflections by a new computer program revealed an anisotropic strain of the two twinning systems of the film. (orig.)

  2. On some classes of two-dimensional local models in discrete two-dimensional monatomic FPU lattice with cubic and quartic potential

    International Nuclear Information System (INIS)

    Quan, Xu; Qiang, Tian

    2009-01-01

    This paper discusses the two-dimensional discrete monatomic Fermi–Pasta–Ulam lattice, by using the method of multiple-scale and the quasi-discreteness approach. By taking into account the interaction between the atoms in the lattice and their nearest neighbours, it obtains some classes of two-dimensional local models as follows: two-dimensional bright and dark discrete soliton trains, two-dimensional bright and dark line discrete breathers, and two-dimensional bright and dark discrete breather. (condensed matter: structure, thermal and mechanical properties)

  3. Static Internal Performance of a Two-Dimensional Convergent-Divergent Nozzle with External Shelf

    Science.gov (United States)

    Lamb, Milton; Taylor, John G.; Frassinelli, Mark C.

    1996-01-01

    An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a two-dimensional convergent-divergent nozzle. The nozzle design was tested with dry and afterburning throat areas, which represent different power settings and three expansion ratios. For each of these configurations, three trailing-edge geometries were tested. The baseline geometry had a straight trailing edge. Two different shaping techniques were applied to the baseline nozzle design to reduce radar observables: the scarfed design and the sawtooth design. A flat plate extended downstream of the lower divergent flap trailing edge parallel to the model centerline to form a shelf-like expansion surface. This shelf was designed to shield the plume from ground observation (infrared radiation (IR) signature suppression). The shelf represents the part of the aircraft structure that might be present in an installed configuration. These configurations were tested at nozzle pressure ratios from 2.0 to 12.0.

  4. Status for the two-dimensional Navier-Stokes solver EllipSys2D

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F.; Soerensen, N.; Johansen, J.

    2001-08-01

    This report sets up an evaluation of two-dimensional Navier-Stokes solver EllipSys2D in its present state. This code is used for blade aerodynamics simulations in the Aeroelastic Design group at Risoe. Two airfoils are investigated by computing the flow at several angles of attack ranging from the linear to the stalled region. The computational data are compared to experimental data and numerical results from other computational codes. Several numerical aspects are studied, as mesh dependency, convective scheme, steady state versus unsteady computations, transition modelling. Some general conclusions intended to help in using this code for numerical simulations are given. (au)

  5. Critical Behaviour of Pure and Site-Random Two Dimensional Antiferromagnets

    DEFF Research Database (Denmark)

    Birgenau, R. J.; Als-Nielsen, Jens Aage; Shirane, G.

    1977-01-01

    Quasielastic neutron scattering studies of the static critical behavior in the two-dimensional antiferromagnets K2NiF4, K2MnF4, and Rb2Mn0.5Ni0.5F4 are reported. For T......Quasielastic neutron scattering studies of the static critical behavior in the two-dimensional antiferromagnets K2NiF4, K2MnF4, and Rb2Mn0.5Ni0.5F4 are reported. For T...

  6. Exact lattice supersymmetry: The two-dimensional N=2 Wess-Zumino model

    International Nuclear Information System (INIS)

    Catterall, Simon; Karamov, Sergey

    2002-01-01

    We study the two-dimensional Wess-Zumino model with extended N=2 supersymmetry on the lattice. The lattice prescription we choose has the merit of preserving exactly a single supersymmetric invariance at finite lattice spacing a. Furthermore, we construct three other transformations of the lattice fields under which the variation of the lattice action vanishes to O(ga 2 ) where g is a typical interaction coupling. These four transformations correspond to the two Majorana supercharges of the continuum theory. We also derive lattice Ward identities corresponding to these exact and approximate symmetries. We use dynamical fermion simulations to check the equality of the mass gaps in the boson and fermion sectors and to check the lattice Ward identities. At least for weak coupling we see no problems associated with a lack of reflection positivity in the lattice action and find good agreement with theory. At strong coupling we provide evidence that problems associated with a lack of reflection positivity are evaded for small enough lattice spacing

  7. Two-dimensional fourier transform spectrometer

    Science.gov (United States)

    DeFlores, Lauren; Tokmakoff, Andrei

    2013-09-03

    The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

  8. SU-F-J-88: Comparison of Two Deformable Image Registration Algorithms for CT-To-CT Contour Propagation

    Energy Technology Data Exchange (ETDEWEB)

    Gopal, A; Xu, H; Chen, S [University of Maryland School of Medicine, Columbia, MD (United States)

    2016-06-15

    Purpose: To compare the contour propagation accuracy of two deformable image registration (DIR) algorithms in the Raystation treatment planning system – the “Hybrid” algorithm based on image intensities and anatomical information; and the “Biomechanical” algorithm based on linear anatomical elasticity and finite element modeling. Methods: Both DIR algorithms were used for CT-to-CT deformation for 20 lung radiation therapy patients that underwent treatment plan revisions. Deformation accuracy was evaluated using landmark tracking to measure the target registration error (TRE) and inverse consistency error (ICE). The deformed contours were also evaluated against physician drawn contours using Dice similarity coefficients (DSC). Contour propagation was qualitatively assessed using a visual quality score assigned by physicians, and a refinement quality score (0DIR (TRE = 3.2 mm) performed better than the biomechanical DIR (TRE = 4.3 mm) with landmark tracking. Both algorithms had comparable DSC (DSC > 0.9 for lungs, > 0.85 for heart, > 0.8 for liver) and similar qualitative assessments (VQS < 0.35, RQS > 0.75 for lungs). When anatomical structures were used to control the deformation, the DSC improved more significantly for the biomechanical DIR compared to the hybrid DIR, while the VQS and RQS improved only for the controlling structures. However, while the inclusion of controlling structures improved the TRE for the hybrid DIR, it increased the TRE for the biomechanical DIR. Conclusion: The hybrid DIR was found to perform slightly better than the biomechanical DIR based on lower TRE while the DSC, VQS, and RQS studies yielded comparable results for both. The use of controlling structures showed considerable improvement in the hybrid DIR results and is recommended for clinical use in

  9. Two-dimensional beam profiles and one-dimensional projections

    Science.gov (United States)

    Findlay, D. J. S.; Jones, B.; Adams, D. J.

    2018-05-01

    One-dimensional projections of improved two-dimensional representations of transverse profiles of particle beams are proposed for fitting to data from harp-type monitors measuring beam profiles on particle accelerators. Composite distributions, with tails smoothly matched on to a central (inverted) parabola, are shown to give noticeably better fits than single gaussian and single parabolic distributions to data from harp-type beam profile monitors all along the proton beam transport lines to the two target stations on the ISIS Spallation Neutron Source. Some implications for inferring beam current densities on the beam axis are noted.

  10. Dynamic three-dimensional display of common congenital cardiac defects from reconstruction of two-dimensional echocardiographic images.

    Science.gov (United States)

    Hsieh, K S; Lin, C C; Liu, W S; Chen, F L

    1996-01-01

    Two-dimensional echocardiography had long been a standard diagnostic modality for congenital heart disease. Further attempts of three-dimensional reconstruction using two-dimensional echocardiographic images to visualize stereotypic structure of cardiac lesions have been successful only recently. So far only very few studies have been done to display three-dimensional anatomy of the heart through two-dimensional image acquisition because such complex procedures were involved. This study introduced a recently developed image acquisition and processing system for dynamic three-dimensional visualization of various congenital cardiac lesions. From December 1994 to April 1995, 35 cases were selected in the Echo Laboratory here from about 3000 Echo examinations completed. Each image was acquired on-line with specially designed high resolution image grazmber with EKG and respiratory gating technique. Off-line image processing using a window-architectured interactive software package includes construction of 2-D ehcocardiographic pixel to 3-D "voxel" with conversion of orthogonal to rotatory axial system, interpolation, extraction of region of interest, segmentation, shading and, finally, 3D rendering. Three-dimensional anatomy of various congenital cardiac defects was shown, including four cases with ventricular septal defects, two cases with atrial septal defects, and two cases with aortic stenosis. Dynamic reconstruction of a "beating heart" is recorded as vedio tape with video interface. The potential application of 3D display of the reconstruction from 2D echocardiographic images for the diagnosis of various congenital heart defects has been shown. The 3D display was able to improve the diagnostic ability of echocardiography, and clear-cut display of the various congenital cardiac defects and vavular stenosis could be demonstrated. Reinforcement of current techniques will expand future application of 3D display of conventional 2D images.

  11. Surface topography to reflectivity mapping in two-dimensional photonic crystals designed in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Husanu, M.A.; Ganea, C.P. [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele, Ilfov (Romania); Anghel, I. [National Institute for Laser, Plasma & Radiation Physics, Atomistilor 409, 077125 Magurele (Romania); University of Bucharest, Faculty of Physics, Atomistilor 405, 077125 Magurele (Romania); Florica, C.; Rasoga, O. [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele, Ilfov (Romania); Popescu, D.G., E-mail: dana.popescu@infim.ro [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele, Ilfov (Romania)

    2015-11-15

    Highlights: • Laser ablation is used for drilling a periodic 2D photonic structure. • Confinement of radiation is revealed by infra-red spectromicroscopy correlated with numerical calculations. • Telecommunication range is accessible upon tuning conveniently the processing parameters. - Abstract: Light confinement in a two dimensional photonic crystal (2D PhC) with hexagonal symmetry is studied using infra-red reflectance spectromicroscopy and numerical calculations. The structure has been realized by laser ablation, using a pulsed laser (λ = 775 nm), perforating an In-doped Ge wafer and creating a lattice of holes with well-defined symmetry. Correlating the spectral signature of the photonic gaps recorded experimentally with the results obtained in the finite difference time domain and finite difference frequency domain calculations, we established the relationship between the geometric parameters of the structure (lattice constants, shape of the hole) and its efficiency in trapping and guiding the radiation in a well-defined frequency range. Besides the gap in the low energy range of transversal electric modes, a second one is identified in the telecommunication range, originating in the localization of the leaky modes within the radiation continuum. The emerging picture is of a device with promising characteristics as an alternative to Si-based technology in photonic device fabrication with special emphasize in energy storage and conversion.

  12. Non-collinear upconversion of infrared light

    DEFF Research Database (Denmark)

    Pedersen, Christian; Hu, Qi; Høgstedt, Lasse

    2014-01-01

    Two dimensional mid-infrared upconversion imaging provides unique spectral and spatial information showing good potential for mid- infrared spectroscopy and hyperspectral imaging. However, to extract spectral or spatial information from the upconverted images an elaborate model is needed, which...... includes non-collinear interaction. We derive here a general theory providing the far field of the upconverted light when two arbitrary fields interact inside a non linear crystal. Theoretical predictions are experimentally verified for incoherent radiation and subsequently applied to previously published...

  13. FPGA Implementation of one-dimensional and two-dimensional cellular automata

    International Nuclear Information System (INIS)

    D'Antone, I.

    1999-01-01

    This report describes the hardware implementation of one-dimensional and two-dimensional cellular automata (CAs). After a general introduction to the cellular automata, we consider a one-dimensional CA used to implement pseudo-random techniques in built-in self test for VLSI. Due to the increase in digital ASIC complexity, testing is becoming one of the major costs in the VLSI production. The high electronics complexity, used in particle physics experiments, demands higher reliability than in the past time. General criterions are given to evaluate the feasibility of the circuit used for testing and some quantitative parameters are underlined to optimize the architecture of the cellular automaton. Furthermore, we propose a two-dimensional CA that performs a peak finding algorithm in a matrix of cells mapping a sub-region of a calorimeter. As in a two-dimensional filtering process, the peaks of the energy clusters are found in one evolution step. This CA belongs to Wolfram class II cellular automata. Some quantitative parameters are given to optimize the architecture of the cellular automaton implemented in a commercial field programmable gate array (FPGA)

  14. Quasi-two-dimensional holography

    International Nuclear Information System (INIS)

    Kutzner, J.; Erhard, A.; Wuestenberg, H.; Zimpfer, J.

    1980-01-01

    The acoustical holography with numerical reconstruction by area scanning is memory- and time-intensive. With the experiences by the linear holography we tried to derive a scanning for the evaluating of the two-dimensional flaw-sizes. In most practical cases it is sufficient to determine the exact depth extension of a flaw, whereas the accuracy of the length extension is less critical. For this reason the applicability of the so-called quasi-two-dimensional holography is appropriate. The used sound field given by special probes is divergent in the inclined plane and light focussed in the perpendicular plane using cylindrical lenses. (orig.) [de

  15. Iterative Two- and One-Dimensional Methods for Three-Dimensional Neutron Diffusion Calculations

    International Nuclear Information System (INIS)

    Lee, Hyun Chul; Lee, Deokjung; Downar, Thomas J.

    2005-01-01

    Two methods are proposed for solving the three-dimensional neutron diffusion equation by iterating between solutions of the two-dimensional (2-D) radial and one-dimensional (1-D) axial solutions. In the first method, the 2-D/1-D equations are coupled using a current correction factor (CCF) with the average fluxes of the lower and upper planes and the axial net currents at the plane interfaces. In the second method, an analytic expression for the axial net currents at the interface of the planes is used for planar coupling. A comparison of the new methods is made with two previously proposed methods, which use interface net currents and partial currents for planar coupling. A Fourier convergence analysis of the four methods was performed, and results indicate that the two new methods have at least three advantages over the previous methods. First, the new methods are unconditionally stable, whereas the net current method diverges for small axial mesh size. Second, the new methods provide better convergence performance than the other methods in the range of practical mesh sizes. Third, the spectral radii of the new methods asymptotically approach zero as the mesh size increases, while the spectral radius of the partial current method approaches a nonzero value as the mesh size increases. Of the two new methods proposed here, the analytic method provides a smaller spectral radius than the CCF method, but the CCF method has several advantages over the analytic method in practical applications

  16. Matching Two-dimensional Gel Electrophoresis' Spots

    DEFF Research Database (Denmark)

    Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza

    2012-01-01

    This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar...

  17. Topology optimization of two-dimensional waveguides

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2003-01-01

    In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....

  18. Traditional Semiconductors in the Two-Dimensional Limit.

    Science.gov (United States)

    Lucking, Michael C; Xie, Weiyu; Choe, Duk-Hyun; West, Damien; Lu, Toh-Ming; Zhang, S B

    2018-02-23

    Interest in two-dimensional materials has exploded in recent years. Not only are they studied due to their novel electronic properties, such as the emergent Dirac fermion in graphene, but also as a new paradigm in which stacking layers of distinct two-dimensional materials may enable different functionality or devices. Here, through first-principles theory, we reveal a large new class of two-dimensional materials which are derived from traditional III-V, II-VI, and I-VII semiconductors. It is found that in the ultrathin limit the great majority of traditional binary semiconductors studied (a series of 28 semiconductors) are not only kinetically stable in a two-dimensional double layer honeycomb structure, but more energetically stable than the truncated wurtzite or zinc-blende structures associated with three dimensional bulk. These findings both greatly increase the landscape of two-dimensional materials and also demonstrate that in the double layer honeycomb form, even ordinary semiconductors, such as GaAs, can exhibit exotic topological properties.

  19. Two-trace two-dimensional (2T2D) correlation spectroscopy - A method for extracting useful information from a pair of spectra

    Science.gov (United States)

    Noda, Isao

    2018-05-01

    Two-trace two-dimensional (2T2D) correlation spectroscopy, where a pair of spectra are compared as 2D maps by a form of cross correlation analysis, is introduced. In 2T2D, spectral intensity changes of bands arising from the same origin, which cannot change independently of each other, are synchronized. Meanwhile, those arising from different sources may and often do change asynchronously. By taking advantage of this property, one can distinguish and classify a number of contributing bands present in the original pair of spectra in a systematic manner. Highly overlapped neighboring bands originating from different sources can also be identified by the presence of asynchronous cross peaks, thus enhancing the apparent spectral resolution. Computational procedure to obtain 2T2D correlation spectra and their interpretation method, as well as an illustrative description of the basic concept in the vector phase space, are provided. 2T2D spectra may also be viewed as individual building blocks of the generalized 2D correlation spectra derived from a series of more than two spectral data. Some promising application potentials of 2T2D correlation and integration with established advanced 2D correlation techniques are discussed.

  20. Sufficient Controllability Condition for Affine Systems with Two-Dimensional Control and Two-Dimensional Zero Dynamics

    Directory of Open Access Journals (Sweden)

    D. A. Fetisov

    2015-01-01

    Full Text Available The controllability conditions are well known if we speak about linear stationary systems: a linear stationary system is controllable if and only if the dimension of the state vector is equal to the rank of the controllability matrix. The concept of the controllability matrix is extended to affine systems, but relations between affine systems controllability and properties of this matrix are more complicated. Various controllability conditions are set for affine systems, but they deal as usual either with systems of some special form or with controllability in some small neighborhood of the concerned point. An affine system is known to be controllable if the system is equivalent to a system of a canonical form, which is defined and regular in the whole space of states. In this case, the system is said to be feedback linearizable in the space of states. However there are examples, which illustrate that a system can be controllable even if it is not feedback linearizable in any open subset in the space of states. In this article we deal with such systems.Affine systems with two-dimensional control are considered. The system in question is assumed to be equivalent to a system of a quasicanonical form with two-dimensional zero dynamics which is defined and regular in the whole space of states. Therefore the controllability of the original system is equivalent to the controllability of the received system of a quasicanonical form. In this article the sufficient condition for an available solution of the terminal problem is proven for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. The condition is valid in the case of an arbitrary time interval and arbitrary initial and finite states of the system. Therefore the controllability condition is set for systems of a quasicanonical form with two-dimensional control and two-dimensional zero dynamics. An example is given which illustrates how the proved

  1. Design of a rotational three-dimensional nonimaging device by a compensated two-dimensional design process.

    Science.gov (United States)

    Yang, Yi; Qian, Ke-Yuan; Luo, Yi

    2006-07-20

    A compensation process has been developed to design rotational three-dimensional (3D) nonimaging devices. By compensating the desired light distribution during a two-dimensional (2D) design process for an extended Lambertian source using a compensation coefficient, the meridian plane of a 3D device with good performance can be obtained. This method is suitable in many cases with fast calculation speed. Solutions to two kinds of optical design problems have been proposed, and the limitation of this compensated 2D design method is discussed.

  2. Analysis of Two-Dimensional Electrophoresis Gel Images

    DEFF Research Database (Denmark)

    Pedersen, Lars

    2002-01-01

    This thesis describes and proposes solutions to some of the currently most important problems in pattern recognition and image analysis of two-dimensional gel electrophoresis (2DGE) images. 2DGE is the leading technique to separate individual proteins in biological samples with many biological...

  3. Two- and three-dimensional CT evaluation of sacral and pelvic anomalies

    International Nuclear Information System (INIS)

    Kuhlman, J.E.; Fishman, E.K.; Magid, D.

    1988-01-01

    Pelvic anomalies are difficult to evaluate with standard techniques. Detailed knowledge of the existing pelvic structures and musculature is essential for successful repair. The authors evaluated 12 patients with complex malformations of the pelvis using two- and three-dimensional imaging. The anomalies included bladder exstrophy (n = 4), cloacal exstrophy (n = 1), duplicated and absent sacrum (n = 3), myelomeningoceles (n = 2), and diastrophic dwarfism (n = 2). The two-dimensional images consisted of sequential coronal and sagittal reconstructions that could be reviewed dynamically on screen. Three-dimensional images were generated on the Pixar imaging computer with use of volumetric rendering. Two- and three-dimensional CT proved complementary in the evaluation of pelvic anomalies, providing optimal information from transaxial CT data

  4. Reliability of tunnel angle in ACL reconstruction: two-dimensional versus three-dimensional guide technique.

    Science.gov (United States)

    Leiter, Jeff R S; de Korompay, Nevin; Macdonald, Lindsey; McRae, Sheila; Froese, Warren; Macdonald, Peter B

    2011-08-01

    To compare the reliability of tibial tunnel position and angle produced with a standard ACL guide (two-dimensional guide) or Howell 65° Guide (three-dimensional guide) in the coronal and sagittal planes. In the sagittal plane, the dependent variables were the angle of the tibial tunnel relative to the tibial plateau and the position of the tibial tunnel with respect to the most posterior aspect of the tibia. In the coronal plane, the dependent variables were the angle of the tunnel with respect to the medial joint line of the tibia and the medial and lateral placement of the tibial tunnel relative to the most medial aspect of the tibia. The position and angle of the tibial tunnel in the coronal and sagittal planes were determined from anteroposterior and lateral radiographs, respectively, taken 2-6 months postoperatively. The two-dimensional and three-dimensional guide groups included 28 and 24 sets of radiographs, respectively. Tibial tunnel position was identified, and tunnel angle measurements were completed. Multiple investigators measured the position and angle of the tunnel 3 times, at least 7 days apart. The angle of the tibial tunnel in the coronal plane using a two-dimensional guide (61.3 ± 4.8°) was more horizontal (P guide (64.7 ± 6.2°). The position of the tibial tunnel in the sagittal plane was more anterior (P guide group compared to the three-dimensional guide group (43.3 ± 2.9%). The Howell Tibial Guide allows for reliable placement of the tibial tunnel in the coronal plane at an angle of 65°. Tibial tunnels were within the anatomical footprint of the ACL with either technique. Future studies should investigate the effects of tibial tunnel angle on knee function and patient quality of life. Case-control retrospective comparative study, Level III.

  5. Two-dimensional network formation of cardiac myocytes in agar microculture chip with 1480 nm infrared laser photo-thermal etching.

    Science.gov (United States)

    Kojima, Kensuke; Moriguchi, Hiroyuki; Hattori, Akihiro; Kaneko, Tomoyuki; Yasuda, Kenji

    2003-11-01

    We have developed a new method that enables agar microstructures to be used to cultivate cells and that allows cell network patterns to be controlled. The method makes use of non-contact three-dimensional photo-thermal etching with a 1480 nm infrared focused laser beam, which is strongly absorbed by water and agar gel, to form the shapes of agar microstructures. It allows microstructures to be easily formed in an agar layer within a few minutes, with cell-culture holes formed by the spot heating of a 100 mW laser and tunnels by the tracing of a 100 microm s(-1), 40 mW laser. We cultivated rat cardiac myocytes in adjacent microstructures and observed synchronized beating in them 90 min after they had made physical contact. Our results indicate that the system can make and use microstructures for cell-network cultivation in a minimal amount of time without any expensive microfabrication facilities or complicated procedures.

  6. MO-C-17A-05: A Three-Dimensional Head-And-Neck Phantom for Validation of Kilovoltage- and Megavoltage-Based Deformable Image Registration

    International Nuclear Information System (INIS)

    Kirby, N; Singhrao, K; Pouliot, J

    2014-01-01

    Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage and megavoltage computed tomography and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kilovoltage (kV) and megavoltage (MV) imaging. The phantom opened along a sagittal midsection to reveal nonradiopaque markers, which were used to characterize the phantom deformation. The deformed and undeformed phantom was scanned with kV and MV computed tomography. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM Software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV-kV registration, MIM made the lowest mean error, and Velocity made the lowest maximum error. For MV-MV, kV-MV, and kV-MC Velocity produced both the lowest mean and lowest maximum errors. Conclusion: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool for this purpose

  7. Two-Dimensional Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Bo Jia

    2015-01-01

    (BP networks. However, like many other methods, ELM is originally proposed to handle vector pattern while nonvector patterns in real applications need to be explored, such as image data. We propose the two-dimensional extreme learning machine (2DELM based on the very natural idea to deal with matrix data directly. Unlike original ELM which handles vectors, 2DELM take the matrices as input features without vectorization. Empirical studies on several real image datasets show the efficiency and effectiveness of the algorithm.

  8. Navigator channel adaptation to reconstruct three dimensional heart volumes from two dimensional radiotherapy planning data

    International Nuclear Information System (INIS)

    Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L; Hodgson, David C; Sharpe, Michael B; Brock, Kristy K

    2012-01-01

    Biologically-based models that utilize 3D radiation dosimetry data to estimate the risk of late cardiac effects could have significant utility for planning radiotherapy in young patients. A major challenge arises from having only 2D treatment planning data for patients with long-term follow-up. In this study, we evaluate the accuracy of an advanced deformable image registration (DIR) and navigator channels (NC) adaptation technique to reconstruct 3D heart volumes from 2D radiotherapy planning images for Hodgkin's Lymphoma (HL) patients. Planning CT images were obtained for 50 HL patients who underwent mediastinal radiotherapy. Twelve image sets (6 male, 6 female) were used to construct a male and a female population heart model, which was registered to 23 HL 'Reference' patients' CT images using a DIR algorithm, MORFEUS. This generated a series of population-to-Reference patient specific 3D deformation maps. The technique was independently tested on 15 additional 'Test' patients by reconstructing their 3D heart volumes using 2D digitally reconstructed radiographs (DRR). The technique involved: 1) identifying a matching Reference patient for each Test patient using thorax measurements, 2) placement of six NCs on matching Reference and Test patients' DRRs to capture differences in significant heart curvatures, 3) adapting the population-to-Reference patient-specific deformation maps to generate population-to-Test patient-specific deformation maps using linear and bilinear interpolation methods, 4) applying population-to-Test patient specific deformation to the population model to reconstruct Test-patient specific 3D heart models. The percentage volume overlap between the NC-adapted reconstruction and actual Test patient's true heart volume was calculated using the Dice coefficient. The average Dice coefficient expressed as a percentage between the NC-adapted and actual Test model was 89.4 ± 2.8%. The modified NC adaptation

  9. Novel DiR and SPIO nanoparticles embedded PEG-PLGA nanobubbles as a multimodalimaging contrast agent.

    Science.gov (United States)

    Luo, Binhua; Zhang, Huajie; Liu, Xuhan; Rao, Rong; Wu, Yun; Liu, Wei

    2015-01-01

    Fluorescence dye DiR and superparamagnetic iron oxide nanoparticles (SPIONs) embedded in PEG-PLGA nanobubbles (DiR-SPIO-NBs) were produced using double emulsion method on a membrane of Shirasu porous glass (SPG). The nanobubbles encapsulated with DiR and SPIONs had a liquid core (perfluoropentane) and a PEG-PLGA shell. DiR-SPIO-NBs showed biocompatibility based on MTT cytotoxicity and hemolysis studies. The PFP encapsulated in the nanobubbles experienced phase transition under ultrasonic irradation. Nanobubbles dispersed well in saline over 3 months, and the relaxivity was 127.9 mM(-1)s(-1), suggesting that it could be used as a contrast agent in MRI. The MR and fluorescence images in vivo demonstrated that the signal intensity in the spleen and liver was significantly enhanced with the treatment of nanobubbles. In addition, results of ultrasound images suggested that the nanobubbles had persistent contrast ability. In conclusion, nanobubbles could be utilized as an US/MRI/fluorescence contrast agent.

  10. Screened Raman response in two-dimensional d(x2-y2)-wave superconductors: Relative intensities in different symmetry channels

    DEFF Research Database (Denmark)

    Wenger, F.; Käll, M.

    1997-01-01

    We analyze the Raman-scattering response in a two-dimensional d(x2-y2)-wave superconductor and point out a strong suppression of relative intensity in the screened A(1g) channel compared to the B-1g channel for a generic tight-binding model. This is in contrast with the observed behavior in high...

  11. Thermal transport in a two-dimensional Z2 spin liquid

    Science.gov (United States)

    Metavitsiadis, Alexandros; Pidatella, Angelo; Brenig, Wolfram

    2017-11-01

    We study the dynamical thermal conductivity of the two-dimensional Kitaev spin model on the honeycomb lattice. We find a strongly temperature dependent low-frequency spectral intensity as a direct consequence of fractionalization of spins into mobile Majorana matter and a static Z2 gauge field. The latter acts as an emergent thermally activated disorder, leading to the appearance of a pseudogap which closes in the thermodynamic limit, indicating a dissipative heat conductor. Our analysis is based on complementary calculations of the current correlation function, comprising exact diagonalization by means of a complete summation over all gauge sectors, as well as a phenomenological mean-field treatment of thermal gauge fluctuations, valid at intermediate and high temperatures. The results will also be contrasted against the conductivity discarding gauge fluctuations.

  12. Two-and three-dimensional CT reconstruction

    International Nuclear Information System (INIS)

    Fishman, E.K.; Ney, D.R.; Magid, D.

    1990-01-01

    This paper determines the optimal imaging sequence for creating two- and three-dimensional (2D/3D) skeletal reconstructions from CT data. A cadaver femur, a bone phantom, and a surgically created fracture were scanned with varying protocols to determine the optimal protocol for creating 2D/3D images. The scanning protocols used varying section thickness (2, 4, and 8 mm) as well as scan spacing (2, 3, 4 and 8 mm). All images were reconstructed into 2D data sets with a bicubic interpolation and 3D datasets with volumetric rendering. The results were reviewed by two reviewers to determine the quality of images reconstruction

  13. Multi-institutional Validation Study of Commercially Available Deformable Image Registration Software for Thoracic Images

    International Nuclear Information System (INIS)

    Kadoya, Noriyuki; Nakajima, Yujiro; Saito, Masahide; Miyabe, Yuki; Kurooka, Masahiko; Kito, Satoshi; Fujita, Yukio; Sasaki, Motoharu; Arai, Kazuhiro; Tani, Kensuke; Yagi, Masashi; Wakita, Akihisa; Tohyama, Naoki; Jingu, Keiichi

    2016-01-01

    Purpose: To assess the accuracy of the commercially available deformable image registration (DIR) software for thoracic images at multiple institutions. Methods and Materials: Thoracic 4-dimensional (4D) CT images of 10 patients with esophageal or lung cancer were used. Datasets for these patients were provided by DIR-lab ( (dir-lab.com)) and included a coordinate list of anatomic landmarks (300 bronchial bifurcations) that had been manually identified. Deformable image registration was performed between the peak-inhale and -exhale images. Deformable image registration error was determined by calculating the difference at each landmark point between the displacement calculated by DIR software and that calculated by the landmark. Results: Eleven institutions participated in this study: 4 used RayStation (RaySearch Laboratories, Stockholm, Sweden), 5 used MIM Software (Cleveland, OH), and 3 used Velocity (Varian Medical Systems, Palo Alto, CA). The ranges of the average absolute registration errors over all cases were as follows: 0.48 to 1.51 mm (right-left), 0.53 to 2.86 mm (anterior-posterior), 0.85 to 4.46 mm (superior-inferior), and 1.26 to 6.20 mm (3-dimensional). For each DIR software package, the average 3-dimensional registration error (range) was as follows: RayStation, 3.28 mm (1.26-3.91 mm); MIM Software, 3.29 mm (2.17-3.61 mm); and Velocity, 5.01 mm (4.02-6.20 mm). These results demonstrate that there was moderate variation among institutions, although the DIR software was the same. Conclusions: We evaluated the commercially available DIR software using thoracic 4D-CT images from multiple centers. Our results demonstrated that DIR accuracy differed among institutions because it was dependent on both the DIR software and procedure. Our results could be helpful for establishing prospective clinical trials and for the widespread use of DIR software. In addition, for clinical care, we should try to find the optimal DIR procedure using thoracic 4D

  14. Two-dimensional flexible nanoelectronics

    Science.gov (United States)

    Akinwande, Deji; Petrone, Nicholas; Hone, James

    2014-12-01

    2014/2015 represents the tenth anniversary of modern graphene research. Over this decade, graphene has proven to be attractive for thin-film transistors owing to its remarkable electronic, optical, mechanical and thermal properties. Even its major drawback--zero bandgap--has resulted in something positive: a resurgence of interest in two-dimensional semiconductors, such as dichalcogenides and buckled nanomaterials with sizeable bandgaps. With the discovery of hexagonal boron nitride as an ideal dielectric, the materials are now in place to advance integrated flexible nanoelectronics, which uniquely take advantage of the unmatched portfolio of properties of two-dimensional crystals, beyond the capability of conventional thin films for ubiquitous flexible systems.

  15. A new semi-invasive method for two dimensional pO2 measurements of cortical structures.

    Science.gov (United States)

    Warnat, Jan; Liebsch, Gregor; Stoerr, Eva-Maria; Brawanski, Alexander; Woertgen, Chris

    2008-01-01

    Measuring brain oxygenation in patients with TBI or SAH is of major interest. We present a new semi-invasive method for two dimensional measurements of cortical pO2. For this feasibility study, a porphyrin containing sensor foil was placed directly on the cortex of intubated and variably ventilated Wistar rats. The sensor was excited with a light pulse and pictures of the foil's pO2 dependant emissions were captured with a CCD camera. After online data processing, two-dimensional maps of cortex oxygenation were displayed and analyzed using ROIs (here: arteriole, vein, parenchyma) with a display rate of 7 Hz. The size of one single measurement pixel was 0.03 x 0.03 mm2. The mean pO2 over cortex arterioles was 20.3 +/- 0.69, over veins 17.1 +/- 0.5 and over parenchyma 9.1 +/- 0.6 (mmHg +/- SD). The arterial pO2 showed a good correlation to the pO2 in the ROIs (r = 0.46-0.72, p pO2 values in the ROIs of the cortex. This prototype is capable of obtaining cortical pO2 maps with excellent temporal and spatial resolution and provides simultaneous imaging of the cortex structures.

  16. Control Operator for the Two-Dimensional Energized Wave Equation

    Directory of Open Access Journals (Sweden)

    Sunday Augustus REJU

    2006-07-01

    Full Text Available This paper studies the analytical model for the construction of the two-dimensional Energized wave equation. The control operator is given in term of space and time t independent variables. The integral quadratic objective cost functional is subject to the constraint of two-dimensional Energized diffusion, Heat and a source. The operator that shall be obtained extends the Conjugate Gradient method (ECGM as developed by Hestenes et al (1952, [1]. The new operator enables the computation of the penalty cost, optimal controls and state trajectories of the two-dimensional energized wave equation when apply to the Conjugate Gradient methods in (Waziri & Reju, LEJPT & LJS, Issues 9, 2006, [2-4] to appear in this series.

  17. Three two-dimensional coordination polymers constructed from transition metals and 2,3-norbornanedicarboxylic acid: Hydrothermal synthesis, crystal structures and photocatalytic properties

    Science.gov (United States)

    Zhang, Jia; Wang, Chong-Chen

    2017-02-01

    Three novel coordination polymers based on transition metals like Co(II), Cu(II) and Mn(II), namely [Co2(bpy)2(nbda)2(H2O)22H2O (denoted as BUC-1), [Cu2(bpy)2(nbda)2(H2O)22H2O (BUC-2), [Mn2(bpy)2(nbda)2(H2O)22H2O (BUC-3), (where bpy = 4,4‧-bipyridine, H2nbda = 2,3-norbornanedicarboxylic acid, BUC = Beijing University of Civil Engineering and Architecture), were synthesized under hydrothermal conditions, and characterized by CNH elemental analyses (EA), Fourier Transform infrared spectroscopy (FTIR), and single crystal X-ray diffraction (SCXRD). BUC 1-3 were isostructural and crystallized in the monoclinic space group C2/c, in which the corresponding metal atoms were linked by typical bidentate bpy ligands into two adjacent 1D [M1(bpy)]n2n+ and [M2(bpy)]n2n+ (M = Co(II), Cu(II), Mn(II)), further joined by versatile nbda2- ligands into 2D [M2(bpy)2(nbda)2]n sheets. Finally, three-dimensional supramolecular frameworks were constructed with the aid of the intermolecular hydrogen bonding interactions. BUC 1-3 exhibited different photocatalytic degradation ability to decompose methylene blue (MB) and methyl orange (MO) under UV light irradiation. Additionally, a possible photocatalytic mechanism HOMO-LUMO was proposed and discussed, which was further confirmed by radicals trapping experiments using isopropanol as radical scavenger.

  18. Two-dimensional structure and kinematics of a representative sample of low-z ULIRGs

    International Nuclear Information System (INIS)

    Garcia-Marin, M; Colina, L; Arribas, S

    2008-01-01

    We present the optical INTEGRAL integral field spectroscopy data and Hubble Space Telescope archive images obtained for a representative sample of 22 local Ultraluminous Infrared Galaxies (ULIRGs L IR >10 12 L o-dot ). The sample has been designed for fulfilling a program aimed at studying the internal structure and kinematics of this type of galaxies. Taking advantage of the two-dimensional nature of the data, we study the structure of the stellar and ionized gas, the internal ionization state and the gas kinematics. In this contribution we present the sample and the most important results obtained so far.

  19. Bluish-white-light-emitting diodes based on two-dimensional lead halide perovskite (C6H5C2H4NH3)2PbCl2Br2

    Science.gov (United States)

    Cai, Peiqing; Wang, Xiangfu; Seo, Hyo Jin; Yan, Xiaohong

    2018-04-01

    Bluish-white-light-emitting diodes (BWLEDs) are designed based on the two-dimensional mixed halide perovskite (C6H5C2H4NH3)2PbCl2Br2 at room temperature. Bluish-white electroluminescence devices were fabricated by a spin-coating method. The BWLEDs can be turned on at 4.9 V and depict a maximum luminance of ˜70 cd/m2 at 7 V. Low and room temperature photoluminescence spectra show the coexistence of free exciton and self-trapped exciton luminescence in a deformable lattice. The strategy of achieving white electroluminescence (EL) from mixed halide perovskite reported here can be applied to other two-dimensional perovskites to increase the optoelectronic efficiency of the device in the future.

  20. Two-dimensional numerical experiments with DRIX-2D on two-phase-water-flows referring to the HDR-blowdown-experiments

    International Nuclear Information System (INIS)

    Moesinger, H.

    1979-08-01

    The computer program DRIX-2D has been developed from SOLA-DF. The essential elements of the program structure are described. In order to verify DRIX-2D an Edwards-Blowdown-Experiment is calculated and other numerical results are compared with steady state experiments and models. Numerical experiments on transient two-phase flow, occurring in the broken pipe of a PWR in the case of a hypothetic LOCA, are performed. The essential results of the two-dimensional calculations are: 1. The appearance of a radial profile of void-fraction, velocity, sound speed and mass flow-rate inside the blowdown nozzle. The reason for this is the flow contraction at the nozzle inlet leading to more vapour production in the vicinity of the pipe wall. 2. A comparison between modelling in axisymmetric and Cartesian coordinates and calculations with and without the core barrel show the following: a) The three-dimensional flow pattern at the nozzle inlet is poorly described using Cartesian coordinates. In consequence a considerable difference in pressure history results. b) The core barrel alters the reflection behaviour of the pressure waves oscillating in the blowdown-nozzle. Therefore, the core barrel should be modelled as a wall normal to the nozzle axis. (orig./HP) [de

  1. Learning 2-Dimensional and 3-Dimensional Geometry with Geogebra: Which Would Students Do Better?

    Directory of Open Access Journals (Sweden)

    Zaleha Ismail

    2017-08-01

    Full Text Available The purpose of this study is to examine the geometric thinking of young children who worked with GeoGebra to learn two-dimensional (2-D and three-dimensional (3-D geometry. GeoGebra is an open sourced dynamic mathematics software which is applicable for learning mathematics from primary school to secondary school and to higher education. Thirty pupils studying in second grade (Year 2 at a school located in Pontian, a district in one of the Malaysian state participated in the study. They attended GeoGebra sessions to construct and analyze dynamics of two-dimensional and three-dimensional geometry after learning these topics in the conventional setting. Pretest and posttest on two-dimensional and three-dimensional spatial ability based on Van Hiele level of geometric thinking were administered to the pupils. The comparison between pretest and posttest results demonstrate significant enhancement in visualization and informal deduction for both 2-D and 3-D geometry. Moreover from the intervention, the students benefit most in analyzing 3-D and visualizing 2-D geometry. Interestingly, skills and knowledge acquired through activities using GeoGebra in student-centered learning environment could be successfully transferred to paper and pencil test.

  2. Two-dimensional simulations of multi-hollow VHF SiH4/H2 plasma

    Directory of Open Access Journals (Sweden)

    Li-Wen Su

    2018-02-01

    Full Text Available A triode multi-hollow VHF SiH4/H2 plasma (60 MHz was examined at a pressure of 20 Pa by two-dimensional simulations using the fluid model. In this study, we considered the effect of the rate constant of reaction, SiH3 + SiH3→SiH2 + SiH4, on the plasma characteristics. A typical VHF plasma of a high-electron density with a low-electron temperature was obtained between two discharge electrodes. Spatial profiles of SiH3+, SiH2+, SiH3- and SiH3 densities were similar to that of the electron density while the electron temperature had a maximum value near the two discharge electrodes. It was found that the SiH3 radical density did not decrease rapidly near the substrate and the electron temperature was lower than 1 eV, suggesting that the triode multi-hollow plasma source can provide high quality amorphous silicon with a high deposition rate.

  3. Dose accumulation of multiple high dose rate prostate brachytherapy treatments in two commercially available image registration systems.

    Science.gov (United States)

    Poder, Joel; Yuen, Johnson; Howie, Andrew; Bece, Andrej; Bucci, Joseph

    2017-11-01

    The purpose of this study was to assess whether deformable image registration (DIR) is required for dose accumulation of multiple high dose rate prostate brachytherapy (HDRPBT) plans treated with the same catheter pattern on two different CT datasets. DIR was applied to 20 HDRPBT patients' planning CT images who received two treatment fractions on sequential days, on two different CT datasets, with the same implant. Quality of DIR in Velocity and MIM image registration systems was assessed by calculating the Dice Similarity Coefficient (DSC) and mean distance to agreement (MDA) for the prostate, urethra and rectum contours. Accumulated doses from each system were then calculated using the same DIR technique and dose volume histogram (DVH) parameters compared to manual addition with no DIR. The average DSC was found to be 0.83 (Velocity) and 0.84 (MIM), 0.80 (Velocity) and 0.80 (MIM), 0.80 (Velocity) and 0.81 (MIM), for the prostate, rectum and urethra contours, respectively. The average difference in calculated DVH parameters between the two systems using dose accumulation was less than 1%, and there was no statistically significant difference found between deformably accumulated doses in the two systems versus manual DVH addition with no DIR. Contour propagation using DIR in velocity and MIM was shown to be at least equivalent to inter-observer contouring variability on CT. The results also indicate that dose accumulation through manual addition of DVH parameters may be sufficient for HDRPBT treatments treated with the same catheter pattern on two different CT datasets. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  4. Three-dimensional fluorescence lifetime tomography

    International Nuclear Information System (INIS)

    Godavarty, Anuradha; Sevick-Muraca, Eva M.; Eppstein, Margaret J.

    2005-01-01

    Near-infrared fluorescence tomography using molecularly targeted lifetime-sensitive, fluorescent contrast agents have applications for early-stage cancer diagnostics. Yet, although the measurement of fluorescent lifetime imaging microscopy (FLIM) is extensively used in microscopy and spectroscopy applications, demonstration of fluorescence lifetime tomography for medical imaging is limited to two-dimensional studies. Herein, the feasibility of three-dimensional fluorescence-lifetime tomography on clinically relevant phantom volumes is established, using (i) a gain-modulated intensified charge coupled device (CCD) and modulated laser diode imaging system, (ii) two fluorescent contrast agents, e.g., Indocyanine green and 3-3'-Diethylthiatricarbocyanine iodide differing in their fluorescence lifetime by 0.62 ns, and (iii) a two stage approximate extended Kalman filter reconstruction algorithm. Fluorescence measurements of phase and amplitude were acquired on the phantom surface under different target to background fluorescence absorption (70:1, 100:1) and fluorescence lifetime (1:1, 2.1:1) contrasts at target depths of 1.4-2 cm. The Bayesian tomography algorithm was employed to obtain three-dimensional images of lifetime and absorption owing to the fluorophores

  5. Approximate solutions for the two-dimensional integral transport equation. Solution of complex two-dimensional transport problems

    International Nuclear Information System (INIS)

    Sanchez, Richard.

    1980-11-01

    This work is divided into two parts: the first part deals with the solution of complex two-dimensional transport problems, the second one (note CEA-N-2166) treats the critically mixed methods of resolution. A set of approximate solutions for the isotropic two-dimensional neutron transport problem has been developed using the interface current formalism. The method has been applied to regular lattices of rectangular cells containing a fuel pin, cladding, and water, or homogenized structural material. The cells are divided into zones that are homogeneous. A zone-wise flux expansion is used to formulate a direct collision probability problem within a cell. The coupling of the cells is effected by making extra assumptions on the currents entering and leaving the interfaces. Two codes have been written: CALLIOPE uses a cylindrical cell model and one or three terms for the flux expansion, and NAUSICAA uses a two-dimensional flux representation and does a truly two-dimensional calculation inside each cell. In both codes, one or three terms can be used to make a space-independent expansion of the angular fluxes entering and leaving each side of the cell. The accuracies and computing times achieved with the different approximations are illustrated by numerical studies on two benchmark problems and by calculations performed in the APOLLO multigroup code [fr

  6. Two-dimensional MoS2: A promising building block for biosensors.

    Science.gov (United States)

    Gan, Xiaorong; Zhao, Huimin; Quan, Xie

    2017-03-15

    Recently, two-dimensional (2D) layered nanomaterials have trigged intensive interest due to the intriguing physicochemical properties that stem from a quantum size effect connected with their ultra-thin structure. In particular, 2D molybdenum disulfide (MoS 2 ), as an emerging class of stable inorganic graphene analogs with intrinsic finite bandgap, would possibly complement or even surpass graphene in electronics and optoelectronics fields. In this review, we first discuss the historical development of ultrathin 2D nanomaterials. Then, we are concerned with 2D MoS 2 including its structure-property relationships, synthesis methods, characterization for the layer thickness, and biosensor applications over the past five years. Thereinto, we are highlighting recent advances in 2D MoS 2 -based biosensors, especially emphasize the preparation of sensing elements, roles of 2D MoS 2 , and assay strategies. Finally, on the basis of the current achievements on 2D MoS 2 and other ultrathin layered nanomaterials, perspectives on the challenges and opportunities for the exploration of 2D MoS 2 -based biosensors are put forward. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Two-dimensional topological field theories coupled to four-dimensional BF theory

    International Nuclear Information System (INIS)

    Montesinos, Merced; Perez, Alejandro

    2008-01-01

    Four-dimensional BF theory admits a natural coupling to extended sources supported on two-dimensional surfaces or string world sheets. Solutions of the theory are in one to one correspondence with solutions of Einstein equations with distributional matter (cosmic strings). We study new (topological field) theories that can be constructed by adding extra degrees of freedom to the two-dimensional world sheet. We show how two-dimensional Yang-Mills degrees of freedom can be added on the world sheet, producing in this way, an interactive (topological) theory of Yang-Mills fields with BF fields in four dimensions. We also show how a world sheet tetrad can be naturally added. As in the previous case the set of solutions of these theories are contained in the set of solutions of Einstein's equations if one allows distributional matter supported on two-dimensional surfaces. These theories are argued to be exactly quantizable. In the context of quantum gravity, one important motivation to study these models is to explore the possibility of constructing a background-independent quantum field theory where local degrees of freedom at low energies arise from global topological (world sheet) degrees of freedom at the fundamental level

  8. SONATINA-2H: a computer program for seismic analysis of the two-dimensional horizontal slice HTGR core

    International Nuclear Information System (INIS)

    Ikushima, Takeshi

    1990-02-01

    A Computer program SONATINA-2H has been developed for predicting the behavior of a two-dimensional horizontal HTGR core under seismic excitation. SONATINA-2H is a general two-dimensional computer program capable of analyzing the horizontal slice HTGR core with the fixed side reflector blocks and its restraint structures and the core support structure. In the analytical model, each block is treated as a rigid body and represent one column of the reactor core and is connected to the core support structure by means of column springs and viscous dampers. A single dashpot model is used for the collision process between adjacent blocks. The core support structure is represented by a single block. The computer program SONATINA-2H is capable of analyzing the core behavior for an excitation input applied simultaneously in two mutually perpendicular horizontal directions. In the present report are given, the theoretical formulation of the analytical model, an user's manual to describe the input and output format and sample problems. (author)

  9. Oxygen infrared spectra of oxyhemoglobins and oxymyoglobins. Evidence of two major liganded O2 structures

    International Nuclear Information System (INIS)

    Potter, W.T.; Tucker, M.P.; Houtchens, R.A.; Caughey, W.S.

    1987-01-01

    The dioxygen stretch bands in infrared spectra for solutions of oxy species of human hemoglobin A and its separated subunits, human mutant hemoglobin Zurich (β63His to Arg), rabbit hemoglobin, lamprey, hemoglobin, sperm whale myoglobin, bovine myoglobin, and a sea worm chlorocruorin are examined. Each protein exhibits multiple isotope-sensitive bands between 1160 and 1060 cm -1 for the liganded 16 O 2 , 17 O 2 , and 18 O 2 . The O-O stretch bands for each of the mammalian myoglobins and hemoglobins are similar, with frequencies that differ between proteins by only 3-5 cm -1 . The spectra for the lamprey and sea worm hemoglobins exhibit greater diversity. For all proteins an O-O stretch band expected to occur near 1125 cm -1 for 16 O 2 and 17 O 2 , but not 18 O 2 , appears split by ∼25 cm -1 due to an unidentified perturbation. The spectrum for each dioxygen isotope, if unperturbed, would contain two strong bands for the mammalian myoglobins (1150 and 1120 cm -1 ) and hemoglobins (1155 and 1125 cm -1 ). Two strong bands separated by ∼30 cm -1 for each oxy heme protein subunit indicate that two major protein conformations (structure) that differ substantially in O 2 bonding are present. The two dioxygen structures can result from a combination of dynamic distal and proximal effects upon the O 2 ligand bound in a bent-end-on stereochemistry

  10. Two-dimensional Kagome photonic bandgap waveguide

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou

    2000-01-01

    The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

  11. Two-dimensional microstrip detector for neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Oed, A [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.

  12. KEDUDUKAN HUKUM NOKEP 883-DIR/KPS/10/2012 SEBAGAI DASAR PEMBERIAN HAK PENSIUN BAGI PEKERJA PT BRI PERSERO TBK

    Directory of Open Access Journals (Sweden)

    Asri Wijayanti

    2014-05-01

    Full Text Available Prior to the enactment of Law 13/2003, workers whose did dismissal due to retirement, the right to receive pension funds (for civil servants or rights to severance pay (for private sector workers. The aim of the article to provide an alternative solution for the national case on retired PT BRI Persero Tbk on going at this time, Status of Directors Nokep 883-DIR/KPS/10/2012 SK analyzed based on Article 167 Law 13/2003, this is BRI has included workers/employees in the pension plans whose contributions/premiums paid by the BRI and workers. SK Nokep 883-DIR/KPS/10/2012 Directors has violated Article 167 paragraph (3 of Law 13/2003.

  13. Generating Far-Infrared Radiation By Two-Wave Mixing

    Science.gov (United States)

    Borenstain, Shmuel

    1992-01-01

    Far-infrared radiation 1 to 6 GHz generated by two-wave mixing in asymmetrically grown GaAs/AlxGa1-xAs multiple-quantum-well devices. Two near-infrared semiconductor diode lasers phase-locked. Outputs amplified, then combined in semiconductor nonlinear multiple-quantum-well planar waveguide. Necessary to optimize design of device with respect to three factors: high degree of confinement of electromagnetic field in nonlinear medium to maximize power density, phase matching to extend length of zone of interaction between laser beams in non-linear medium, and nonlinear susceptibility. Devices used as tunable local oscillators in heterodyne-detection radiometers.

  14. Beginning Introductory Physics with Two-Dimensional Motion

    Science.gov (United States)

    Huggins, Elisha

    2009-01-01

    During the session on "Introductory College Physics Textbooks" at the 2007 Summer Meeting of the AAPT, there was a brief discussion about whether introductory physics should begin with one-dimensional motion or two-dimensional motion. Here we present the case that by starting with two-dimensional motion, we are able to introduce a considerable…

  15. Two-dimensional thermofield bosonization

    International Nuclear Information System (INIS)

    Amaral, R.L.P.G.; Belvedere, L.V.; Rothe, K.D.

    2005-01-01

    The main objective of this paper was to obtain an operator realization for the bosonization of fermions in 1 + 1 dimensions, at finite, non-zero temperature T. This is achieved in the framework of the real-time formalism of Thermofield Dynamics. Formally, the results parallel those of the T = 0 case. The well-known two-dimensional Fermion-Boson correspondences at zero temperature are shown to hold also at finite temperature. To emphasize the usefulness of the operator realization for handling a large class of two-dimensional quantum field-theoretic problems, we contrast this global approach with the cumbersome calculation of the fermion-current two-point function in the imaginary-time formalism and real-time formalisms. The calculations also illustrate the very different ways in which the transmutation from Fermi-Dirac to Bose-Einstein statistics is realized

  16. Evaluation on the concentration change of paeoniflorin and glycyrrhizic acid in different formulations of Shaoyao-Gancao-Tang by the tri-level infrared macro-fingerprint spectroscopy and the whole analysis method

    Science.gov (United States)

    Liu, Aoxue; Wang, Jingjuan; Guo, Yizhen; Xiao, Yao; Wang, Yue; Sun, Suqin; Chen, Jianbo

    2018-03-01

    As a kind of common prescriptions, Shaoyao-Gancao-Tang (SGT) contains two Chinese herbs with four different proportions which have different clinical efficacy because of their various components. In order to investigate the herb-herb interaction mechanisms, we used the method of tri-level infrared macro-fingerprint spectroscopy to evaluate the concentration change of active components of four SGTs in this research. Fourier transform infrared spectroscopy (FT-IR) and Second derivative infrared spectroscopy (SD-IR) can recognize the multiple prescriptions directly and simultaneously. 2D-IR spectra enhance the spectral resolution and obtain much new information for discriminating the similar complicated samples of SGT. Furthermore, the whole analysis method from the analysis of the main components to the specific components and the relative content of the components may evaluate the quality of TCM better. Then we concluded that paeoniflorin and glycyrrhizic acid were the highest proportion in active ingredients in SGT-12:1 and the lowest one in SGT-12:12, which matched the HPLC-DAD results. It is demonstrated that the method composed by the tri-level infrared macro-fingerprint spectroscopy and the whole analysis can be applicable for effective, visual and accurate analysis and identification of very complicated and similar mixture systems of traditional Chinese medicine.

  17. Decoherence in two-dimensional quantum walks

    International Nuclear Information System (INIS)

    Oliveira, A. C.; Portugal, R.; Donangelo, R.

    2006-01-01

    We analyze the decoherence in quantum walks in two-dimensional lattices generated by broken-link-type noise. In this type of decoherence, the links of the lattice are randomly broken with some given constant probability. We obtain the evolution equation for a quantum walker moving on two-dimensional (2D) lattices subject to this noise, and we point out how to generalize for lattices in more dimensions. In the nonsymmetric case, when the probability of breaking links in one direction is different from the probability in the perpendicular direction, we have obtained a nontrivial result. If one fixes the link-breaking probability in one direction, and gradually increases the probability in the other direction from 0 to 1, the decoherence initially increases until it reaches a maximum value, and then it decreases. This means that, in some cases, one can increase the noise level and still obtain more coherence. Physically, this can be explained as a transition from a decoherent 2D walk to a coherent 1D walk

  18. Sub-Nanometer Channels Embedded in Two-Dimensional Materials

    KAUST Repository

    Han, Yimo; Li, Ming-yang; Jung, Gang-Seob; Marsalis, Mark A.; Qin, Zhao; Buehler, Markus J.; Li, Lain-Jong; Muller, David A.

    2017-01-01

    Two-dimensional (2D) materials are among the most promising candidates for next-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling1. Thus far, atomically-thin p-n junctions2

  19. Developing cross entropy genetic algorithm for solving Two-Dimensional Loading Heterogeneous Fleet Vehicle Routing Problem (2L-HFVRP)

    Science.gov (United States)

    Paramestha, D. L.; Santosa, B.

    2018-04-01

    Two-dimensional Loading Heterogeneous Fleet Vehicle Routing Problem (2L-HFVRP) is a combination of Heterogeneous Fleet VRP and a packing problem well-known as Two-Dimensional Bin Packing Problem (BPP). 2L-HFVRP is a Heterogeneous Fleet VRP in which these costumer demands are formed by a set of two-dimensional rectangular weighted item. These demands must be served by a heterogeneous fleet of vehicles with a fix and variable cost from the depot. The objective function 2L-HFVRP is to minimize the total transportation cost. All formed routes must be consistent with the capacity and loading process of the vehicle. Sequential and unrestricted scenarios are considered in this paper. We propose a metaheuristic which is a combination of the Genetic Algorithm (GA) and the Cross Entropy (CE) named Cross Entropy Genetic Algorithm (CEGA) to solve the 2L-HFVRP. The mutation concept on GA is used to speed up the algorithm CE to find the optimal solution. The mutation mechanism was based on local improvement (2-opt, 1-1 Exchange, and 1-0 Exchange). The probability transition matrix mechanism on CE is used to avoid getting stuck in the local optimum. The effectiveness of CEGA was tested on benchmark instance based 2L-HFVRP. The result of experiments shows a competitive result compared with the other algorithm.

  20. Two-dimensional Cu2Si sheet: a promising electrode material for nanoscale electronics

    Science.gov (United States)

    Meng Yam, Kah; Guo, Na; Zhang, Chun

    2018-06-01

    Building electronic devices on top of two-dimensional (2D) materials has recently become one of most interesting topics in nanoelectronics. Finding high-performance 2D electrode materials is one central issue in 2D nanoelectronics. In the current study, based on first-principles calculations, we compare the electronic and transport properties of two nanoscale devices. One device consists of two single-atom-thick planar Cu2Si electrodes, and a nickel phthalocyanine (NiPc) molecule in the middle. The other device is made of often-used graphene electrodes and a NiPc molecule. Planer Cu2Si is a new type of 2D material that was recently predicted to exist and be stable under room temperature [11]. We found that at low bias voltages, the electric current through the Cu2Si–NiPc–Cu2Si junction is about three orders higher than that through graphene–NiPc–graphene. Detailed analysis shows that the surprisingly high conductivity of Cu2Si–NiPc–Cu2Si originates from the mixing of the Cu2Si state near Fermi energy and the highest occupied molecular orbital of NiPc. These results suggest that 2D Cu2Si may be an excellent candidate for electrode materials for future nanoscale devices.

  1. Surface Reconstruction-Induced Coincidence Lattice Formation Between Two-Dimensionally Bonded Materials and a Three-Dimensionally Bonded Substrate

    NARCIS (Netherlands)

    Boschker, Jos E.; Momand, Jamo; Bragaglia, Valeria; Wang, Ruining; Perumal, Karthick; Giussani, Alessandro; Kooi, Bart J.; Riechert, Henning; Calarco, Raffaella

    Sb2Te3 films are used for studying the epitaxial registry between two-dimensionally bonded (2D) materials and three-dimensional bonded (3D) substrates. In contrast to the growth of 3D materials, it is found that the formation of coincidence lattices between Sb2Te3 and Si(111) depends on the geometry

  2. Waterlike anomalies in a two-dimensional core-softened potential

    Science.gov (United States)

    Bordin, José Rafael; Barbosa, Marcia C.

    2018-02-01

    We investigate the structural, thermodynamic, and dynamic behavior of a two-dimensional (2D) core-corona system using Langevin dynamics simulations. The particles are modeled by employing a core-softened potential which exhibits waterlike anomalies in three dimensions. In previous studies in a quasi-2D system a new region in the pressure versus temperature phase diagram of structural anomalies was observed. Here we show that for the two-dimensional case two regions in the pressure versus temperature phase diagram with structural, density, and diffusion anomalies are observed. Our findings indicate that, while the anomalous region at lower densities is due the competition between the two length scales in the potential at higher densities, the anomalous region is related to the reentrance of the melting line.

  3. Status of the solar and infrared radiation submodels in the LLNL 1-D and 2-D chemical-transport models

    International Nuclear Information System (INIS)

    Grant, K.E.; Taylor, K.E.; Ellis, J.S.; Wuebbles, D.J.

    1987-07-01

    The authors have implemented a series of state of the art radiation transport submodels in previously developed one dimensional and two dimensional chemical transport models of the troposphere and stratosphere. These submodels provide the capability of calculating accurate solar and infrared heating rates. They are a firm basis for further radiation submodel development as well as for studying interactions between radiation and model dynamics under varying conditions of clear sky, clouds, and aerosols. 37 refs., 3 figs

  4. FireStem2D — A two-dimensional heat transfer model for simulating tree stem injury in fires

    Science.gov (United States)

    Efthalia K. Chatziefstratiou; Gil Bohrer; Anthony S. Bova; Ravishankar Subramanian; Renato P.M. Frasson; Amy Scherzer; Bret W. Butler; Matthew B. Dickinson

    2013-01-01

    FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by...

  5. Two-dimensional confinement of heavy fermions

    International Nuclear Information System (INIS)

    Shishido, Hiroaki; Shibauchi, Takasada; Matsuda, Yuji; Terashima, Takahito

    2010-01-01

    Metallic systems with the strongest electron correlations are realized in certain rare-earth and actinide compounds whose physics are dominated by f-electrons. These materials are known as heavy fermions, so called because the effective mass of the conduction electrons is enhanced via correlation effects up to as much as several hundreds times the free electron mass. To date the electronic structure of all heavy-fermion compounds is essentially three-dimensional. Here we report on the first realization of a two-dimensional heavy-fermion system, where the dimensionality is adjusted in a controllable fashion by fabricating heterostructures using molecular beam epitaxy. The two-dimensional heavy fermion system displays striking deviations from the standard Fermi liquid low-temperature electronic properties. (author)

  6. Linkage analysis by two-dimensional DNA typing

    NARCIS (Netherlands)

    te Meerman, G J; Mullaart, E; Meulen ,van der Martin; den Daas, J H; Morolli, B; Uitterlinden, A G; Vijg, J

    1993-01-01

    In two-dimensional (2-D) DNA typing, genomic DNA fragments are separated, first according to size by electrophoresis in a neutral polyacrylamide gel and second according to sequence by denaturing gradient gel electrophoresis, followed by hybridization analysis using micro- and minisatellite core

  7. Electronic structure in Bi2Sr2CaCu2O8 studied by two dimensional angular correlation of positron annihilation radiations

    International Nuclear Information System (INIS)

    Kondo, H.; Kubota, T.; Nakashima, N.; Tanigawa, S.; Minami, F.; Takekawa, S.

    1992-01-01

    Electronic structure in one of high-Tc-sperconducting materials, Bi 2 Sr 2 CaCu 2 O 8 , was studied by two dimensional angular correlation of positron annihilation radiations (2D-ACAR). The measurements were performed for Bi 2 Sr 2 CaCu 2 O 8 at room temperature and 24K; in the normal and superconducting states. The three dimensional electron momentum density ρ(p) has been reconstructed by using the image reconstruction technique based on a direct Fourier transportation. The reconstructed electron momentum density ρ(p) has been reduced into the reduced electron momentum density n(k) by using the LCW folding procedure. They are compared with that for Cu and Si. The difference in the density distributions between both states was observed. This may be attributed to the smearing by the reduced thermal momenta of positrons. But there is a possibility that the difference is due to the phase transition

  8. Thermal expansion of two-dimensional itinerant nearly ferromagnetic metal

    International Nuclear Information System (INIS)

    Konno, R; Hatayama, N; Takahashi, Y; Nakano, H

    2009-01-01

    Thermal expansion of two-dimensional itinerant nearly ferromagnetic metal is investigated according to the recent theoretical development of magneto-volume effect for the three-dimensional weak ferromagnets. We particularly focus on the T 2 -linear thermal expansion of magnetic origin at low temperatures, so far disregarded by conventional theories. As the effect of thermal spin fluctuations we have found that the T-linear thermal expansion coefficient shows strong enhancement by assuming the double Lorentzian form of the non-interacting dynamical susceptibility justified in the small wave-number and low frequency region. It grows faster in proportional to y -1/2 as we approach the magnetic instability point than two-dimensional nearly antiferromagnetic metals with ln(1/y s ) dependence, where y and y s are the inverses of the reduced uniform and staggered magnetic susceptibilities, respectively. Our result is consistent with the Grueneisen's relation between the thermal expansion coefficient and the specific heat at low temperatures. In 2-dimensional electron gas we find that the thermal expansion coefficient is divergent with a finite y when the higher order term of non-interacting dynamical susceptibility is taken into account.

  9. Two-dimensional topological photonics

    Science.gov (United States)

    Khanikaev, Alexander B.; Shvets, Gennady

    2017-12-01

    Originating from the studies of two-dimensional condensed-matter states, the concept of topological order has recently been expanded to other fields of physics and engineering, particularly optics and photonics. Topological photonic structures have already overturned some of the traditional views on wave propagation and manipulation. The application of topological concepts to guided wave propagation has enabled novel photonic devices, such as reflection-free sharply bent waveguides, robust delay lines, spin-polarized switches and non-reciprocal devices. Discrete degrees of freedom, widely used in condensed-matter physics, such as spin and valley, are now entering the realm of photonics. In this Review, we summarize the latest advances in this highly dynamic field, with special emphasis on the experimental work on two-dimensional photonic topological structures.

  10. Structures of two-dimensional three-body systems

    International Nuclear Information System (INIS)

    Ruan, W.Y.; Liu, Y.Y.; Bao, C.G.

    1996-01-01

    Features of the structure of L = 0 states of a two-dimensional three-body model system have been investigated. Three types of permutation symmetry of the spatial part, namely symmetric, antisymmetric, and mixed, have been considered. A comparison has been made between the two-dimensional system and the corresponding three-dimensional one. The effect of symmetry on microscopic structures is emphasized. (author)

  11. Confined catalysis under two-dimensional materials

    OpenAIRE

    Li, Haobo; Xiao, Jianping; Fu, Qiang; Bao, Xinhe

    2017-01-01

    Small spaces in nanoreactors may have big implications in chemistry, because the chemical nature of molecules and reactions within the nanospaces can be changed significantly due to the nanoconfinement effect. Two-dimensional (2D) nanoreactor formed under 2D materials can provide a well-defined model system to explore the confined catalysis. We demonstrate a general tendency for weakened surface adsorption under the confinement of graphene overlayer, illustrating the feasible modulation of su...

  12. Method for coupling two-dimensional to three-dimensional discrete ordinates calculations

    International Nuclear Information System (INIS)

    Thompson, J.L.; Emmett, M.B.; Rhoades, W.A.; Dodds, H.L. Jr.

    1985-01-01

    A three-dimensional (3-D) discrete ordinates transport code, TORT, has been developed at the Oak Ridge National Laboratory for radiation penetration studies. It is not feasible to solve some 3-D penetration problems with TORT, such as a building located a large distance from a point source, because (a) the discretized 3-D problem is simply too big to fit on the computer or (b) the computing time (and corresponding cost) is prohibitive. Fortunately, such problems can be solved with a hybrid approach by coupling a two-dimensional (2-D) description of the point source, which is assumed to be azimuthally symmetric, to a 3-D description of the building, the region of interest. The purpose of this paper is to describe this hybrid methodology along with its implementation and evaluation in the DOTTOR (Discrete Ordinates to Three-dimensional Oak Ridge Transport) code

  13. Polytypism and unexpected strong interlayer coupling in two-dimensional layered ReS2

    Science.gov (United States)

    Qiao, Xiao-Fen; Wu, Jiang-Bin; Zhou, Linwei; Qiao, Jingsi; Shi, Wei; Chen, Tao; Zhang, Xin; Zhang, Jun; Ji, Wei; Tan, Ping-Heng

    2016-04-01

    Anisotropic two-dimensional (2D) van der Waals (vdW) layered materials, with both scientific interest and application potential, offer one more dimension than isotropic 2D materials to tune their physical properties. Various physical properties of 2D multi-layer materials are modulated by varying their stacking orders owing to significant interlayer vdW coupling. Multilayer rhenium disulfide (ReS2), a representative anisotropic 2D material, was expected to be randomly stacked and lack interlayer coupling. Here, we demonstrate two stable stacking orders, namely isotropic-like (IS) and anisotropic-like (AI) N layer (NL, N > 1) ReS2 are revealed by ultralow- and high-frequency Raman spectroscopy, photoluminescence and first-principles density functional theory calculation. Two interlayer shear modes are observed in AI-NL-ReS2 while only one shear mode appears in IS-NL-ReS2, suggesting anisotropic- and isotropic-like stacking orders in IS- and AI-NL-ReS2, respectively. This explicit difference in the observed frequencies identifies an unexpected strong interlayer coupling in IS- and AI-NL-ReS2. Quantitatively, the force constants of them are found to be around 55-90% of those of multilayer MoS2. The revealed strong interlayer coupling and polytypism in multi-layer ReS2 may stimulate future studies on engineering physical properties of other anisotropic 2D materials by stacking orders.Anisotropic two-dimensional (2D) van der Waals (vdW) layered materials, with both scientific interest and application potential, offer one more dimension than isotropic 2D materials to tune their physical properties. Various physical properties of 2D multi-layer materials are modulated by varying their stacking orders owing to significant interlayer vdW coupling. Multilayer rhenium disulfide (ReS2), a representative anisotropic 2D material, was expected to be randomly stacked and lack interlayer coupling. Here, we demonstrate two stable stacking orders, namely isotropic-like (IS) and

  14. Tuning spin transport across two-dimensional organometallic junctions

    Science.gov (United States)

    Liu, Shuanglong; Wang, Yun-Peng; Li, Xiangguo; Fry, James N.; Cheng, Hai-Ping

    2018-01-01

    We study via first-principles modeling and simulation two-dimensional spintronic junctions made of metal-organic frameworks consisting of two Mn-phthalocyanine ferromagnetic metal leads and semiconducting Ni-phthalocyanine channels of various lengths. These systems exhibit a large tunneling magnetoresistance ratio; the transmission functions of such junctions can be tuned using gate voltage by three orders of magnitude. We find that the origin of this drastic change lies in the orbital alignment and hybridization between the leads and the center electronic states. With physical insight into the observed on-off phenomenon, we predict a gate-controlled spin current switch based on two-dimensional crystallines and offer general guidelines for designing spin junctions using 2D materials.

  15. Kinetics of two-dimensional electron plasma, interacting with fluctuating potential

    International Nuclear Information System (INIS)

    Boiko, I.I.; Sirenko, Y.M.

    1990-01-01

    In this paper, from the first principles, after the fashion of Klimontovich, the authors derive quantum kinetic equation for electron gas, inhomogeneous in z-direction and homogeneous in XY-plane. Special attention is given to the systems with quasi-two-dimensional electron gas (2 DEG), which are widely explored now. Both interaction between the particles of 2 DEG (in general, of several sorts), and interaction with an external system (phonons, impurities, after change carries etc.) are considered. General theory is used to obtain energy and momentum balance equations and relaxation frequencies for 2 DEG in the basis of plane waves. The case of crossed electric and magnetic fields is also treated. As an illustration the problems of 2 DEG scattering on semibounded three-dimensional electron gas and on two-dimensional hole gas are considered; transverse conductivity of nondegenerate 2 DEG, scattered by impurities in ultraquantum magnetic field, is calculated

  16. Infrared spectromicroscopy and magneto-optical imaging stations at SPring-8

    CERN Document Server

    Kimura, S; Sada, T; Okuno, M; Matsunami, M; Shinoda, K; Kimura, H; Moriwaki, T; Yamagata, M; Kondo, Y; Yoshimatsu, Y; Takahashi, T; Fukui, K; Kawamoto, T; Ishikawa, T

    2001-01-01

    At the BL43IR of SPring-8, infrared microanalysis on various kinds of solid specimens under multiple environments with a spatial resolution smaller than 10 mu m in diameter is planned in the infrared region. In order to perform such analysis, two different stations, a multipurpose spectromicroscopy apparatus and a magneto-optical imaging one have been constructed. Measurements on the spatial two-dimensional cross-section of the infrared beam at the spectromicroscopy station have proven that the stations have a good prospective feature in the performance.

  17. Fingerprints of field-induced Berezinskii–Kosterlitz–Thouless transition in quasi-two-dimensional S=1/2 Heisenberg magnets Cu(en)(H2O)2SO4 and Cu(tn)Cl2

    International Nuclear Information System (INIS)

    Baranová, Lucia; Orendáčová, Alžbeta; Čižmár, Erik; Tarasenko, Róbert; Tkáč, Vladimír; Orendáč, Martin; Feher, Alexander

    2016-01-01

    Organo-metallic compounds Cu(en)(H 2 O) 2 SO 4 (en=C 2 H 8 N 2 ) and Cu(tn)Cl 2 (tn=C 3 H 10 N 2 ) representing S=1/2 quasi-two-dimensional Heisenberg antiferromagnets with an effective intra-layer exchange coupling J/k B ≈3 K, have been examined by specific heat measurements at temperatures down to nominally 50 mK and magnetic fields up to 14 T. A comparative analysis of magnetic specific heat in zero magnetic field revealed nearly identical contribution of short-range magnetic correlations and significant differences were observed at lowest temperatures. A phase transition to long-range order was observed in Cu(en)(H 2 O) 2 SO 4 at T C =0.9 K while hidden in Cu(tn)Cl 2 . A response of both compounds to the application of magnetic field has rather universal features characteristic for a field-induced Berezinskii–Kosterlitz–Thouless transition theoretically predicted for ideal two-dimensional magnets. - Highlights: • Magnetic specific heat of Cu(en)(H 2 O) 2 SO 4 (1) and Cu(tn)Cl 2 (2) was analysed. • In zero magnetic field, (1) and (2) behave as quasi-two-dimensional magnets. • We observed universal thermodynamic response of (1) and (2) to applied field. • Features of field-induced Berezinskii–Kosterlitz–Thouless transition were detected.

  18. X-ray imaging device for one-dimensional and two-dimensional radioscopy

    International Nuclear Information System (INIS)

    1978-01-01

    The X-ray imaging device for the selectable one-dimensional or two-dimensional pictures of objects illuminated by X-rays, comprising an X-ray source, an X-ray screen, and an opto-electrical picture development device placed behind the screen, is characterized by an anamorphotic optical system, which is positioned with a one-dimensional illumination between the X-ray screen and the opto-electrical device and that a two-dimensional illumination will be developed, and that in view of the lens system which forms part of the opto-electrical device, there is placed an X-ray screen in a specified beam direction so that a magnified image may be formed by equalisation of the distance between the X-ray screen and the lens system. (G.C.)

  19. Quantitative optical mapping of two-dimensional materials

    DEFF Research Database (Denmark)

    Jessen, Bjarke S.; Whelan, Patrick R.; Mackenzie, David M. A.

    2018-01-01

    The pace of two-dimensional materials (2DM) research has been greatly accelerated by the ability to identify exfoliated thicknesses down to a monolayer from their optical contrast. Since this process requires time-consuming and error-prone manual assignment to avoid false-positives from image...

  20. Hamiltonian formalism of two-dimensional Vlasov kinetic equation.

    Science.gov (United States)

    Pavlov, Maxim V

    2014-12-08

    In this paper, the two-dimensional Benney system describing long wave propagation of a finite depth fluid motion and the multi-dimensional Russo-Smereka kinetic equation describing a bubbly flow are considered. The Hamiltonian approach established by J. Gibbons for the one-dimensional Vlasov kinetic equation is extended to a multi-dimensional case. A local Hamiltonian structure associated with the hydrodynamic lattice of moments derived by D. J. Benney is constructed. A relationship between this hydrodynamic lattice of moments and the two-dimensional Vlasov kinetic equation is found. In the two-dimensional case, a Hamiltonian hydrodynamic lattice for the Russo-Smereka kinetic model is constructed. Simple hydrodynamic reductions are presented.

  1. Two-dimensional correlation spectroscopy in polymer study

    Science.gov (United States)

    Park, Yeonju; Noda, Isao; Jung, Young Mee

    2015-01-01

    This review outlines the recent works of two-dimensional correlation spectroscopy (2DCOS) in polymer study. 2DCOS is a powerful technique applicable to the in-depth analysis of various spectral data of polymers obtained under some type of perturbation. The powerful utility of 2DCOS combined with various analytical techniques in polymer studies and noteworthy developments of 2DCOS used in this field are also highlighted. PMID:25815286

  2. Two-dimensional ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L M; Fridkin, Vladimir M; Palto, Sergei P [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation); Bune, A V; Dowben, P A; Ducharme, Stephen [Department of Physics and Astronomy, Behlen Laboratory of Physics, Center for Materials Research and Analysis, University of Nebraska-Linkoln, Linkoln, NE (United States)

    2000-03-31

    The investigation of the finite-size effect in ferroelectric crystals and films has been limited by the experimental conditions. The smallest demonstrated ferroelectric crystals had a diameter of {approx}200 A and the thinnest ferroelectric films were {approx}200 A thick, macroscopic sizes on an atomic scale. Langmuir-Blodgett deposition of films one monolayer at a time has produced high quality ferroelectric films as thin as 10 A, made from polyvinylidene fluoride and its copolymers. These ultrathin films permitted the ultimate investigation of finite-size effects on the atomic thickness scale. Langmuir-Blodgett films also revealed the fundamental two-dimensional character of ferroelectricity in these materials by demonstrating that there is no so-called critical thickness; films as thin as two monolayers (1 nm) are ferroelectric, with a transition temperature near that of the bulk material. The films exhibit all the main properties of ferroelectricity with a first-order ferroelectric-paraelectric phase transition: polarization hysteresis (switching); the jump in spontaneous polarization at the phase transition temperature; thermal hysteresis in the polarization; the increase in the transition temperature with applied field; double hysteresis above the phase transition temperature; and the existence of the ferroelectric critical point. The films also exhibit a new phase transition associated with the two-dimensional layers. (reviews of topical problems)

  3. Plasma kinetics of Ar/O2 magnetron discharge by two-dimensional multifluid modeling

    International Nuclear Information System (INIS)

    Costin, C.; Minea, T. M.; Popa, G.; Gousset, G.

    2010-01-01

    Multifluid two-dimensional model was developed to describe the plasma kinetics of the direct current Ar/O 2 magnetron, coupling two modules: charged particles and neutrals. The first module deals with three positive ions - Ar + , O 2 + , and O + - and two negative species - e - and O - - treated by the moments of Boltzmann's equation. The second one follows seven neutral species (Ar, O 2 , O, O 3 , and related metastables) by the multicomponent diffusion technique. The two modules are self-consistently coupled by the mass conservation and kinetic coefficients taking into account more than 100 volume reactions. The steady state is obtained when the overall convergence is achieved. Calculations for 10%O 2 in Ar/O 2 mixture at 2.67 and 4 Pa show that the oxygen excited species are mainly created by electron collisions in the negative glow of the discharge. Decreasing the pressure down to 0.67 Pa, the model reveals the nonlocal behavior of the reactive species. The density gradient of O 2 ground state is reversed with respect to all gradients of the other reactive species, since the latter ones originate from the molecular ground state of oxygen. It is also found that the wall reactions drastically modify the space gradient of neutral reactive species, at least as much as the pressure, even if the discharge operates in compound mode.

  4. Characterization and identification of early proteins in Chlamydia trachomatis serovar L2 by two-dimensional gel electrophoresis

    DEFF Research Database (Denmark)

    Lundemose, AG; Birkelund, Svend; Larsen, PM

    1990-01-01

    The synthesis of early proteins from Chlamydia trachomatis serovar L2 was analyzed by two-dimensional gel electrophoresis. By pulse-label experiments, the synthesis of seven proteins was observed at 2 to 8 h postinfection before the major outer membrane protein was detected at 8 to 10 h after...

  5. Nonlinear dynamic characterization of two-dimensional materials

    NARCIS (Netherlands)

    Davidovikj, D.; Alijani, F.; Cartamil Bueno, S.J.; van der Zant, H.S.J.; Amabili, M.; Steeneken, P.G.

    2017-01-01

    Owing to their atomic-scale thickness, the resonances of two-dimensional (2D) material membranes show signatures of nonlinearities at forces of only a few picoNewtons. Although the linear dynamics of membranes is well understood, the exact relation between the nonlinear response and the resonator's

  6. Impurity states in two - and three-dimensional disordered systems

    International Nuclear Information System (INIS)

    Silva, A.F. da; Fabbri, M.

    1984-01-01

    We investigate the microscopic structure of the impurity states in two-and three-dimensional (2D and 3d) disordered systems. A cluster model is outlined for the donor impurity density of states (DIDS) of doped semiconductors. It is shown that the impurity states are very sensitive to a change in the dimensionality of the system, i.e from 3D to 2D system. It is found that all eigenstates become localized in 2D disordered system for a large range of concentration. (Author) [pt

  7. Impurity states in two-and three-dimensional disordered systems

    International Nuclear Information System (INIS)

    Silva, A.F. da; Fabbri, M.

    1984-04-01

    The microscopic structure of the impurity states in two-and three-dimensional (2D and 3D) disordered systems is investigated. A cluster model is outlined for the donor impurity density of states (DIDS) of doped semiconductors. It is shown that the impurity states are very sensitive to a change in the dimensionality of the system, i.e., from 3D to 2D system. It is found that all eigenstates become localized in 2D disordered system for a large range of concentration. (Author) [pt

  8. Two- to three-dimensional crossover in a dense electron liquid in silicon

    Science.gov (United States)

    Matmon, Guy; Ginossar, Eran; Villis, Byron J.; Kölker, Alex; Lim, Tingbin; Solanki, Hari; Schofield, Steven R.; Curson, Neil J.; Li, Juerong; Murdin, Ben N.; Fisher, Andrew J.; Aeppli, Gabriel

    2018-04-01

    Doping of silicon via phosphine exposures alternating with molecular beam epitaxy overgrowth is a path to Si:P substrates for conventional microelectronics and quantum information technologies. The technique also provides a well-controlled material for systematic studies of two-dimensional lattices with a half-filled band. We show here that for a dense (ns=2.8 ×1014 cm-2) disordered two-dimensional array of P atoms, the full field magnitude and angle-dependent magnetotransport is remarkably well described by classic weak localization theory with no corrections due to interaction. The two- to three-dimensional crossover seen upon warming can also be interpreted using scaling concepts developed for anistropic three-dimensional materials, which work remarkably except when the applied fields are nearly parallel to the conducting planes.

  9. Two-dimensional calculus

    CERN Document Server

    Osserman, Robert

    2011-01-01

    The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o

  10. Collapse arresting in an inhomogeneous two-dimensional nonlinear Schrodinger model

    DEFF Research Database (Denmark)

    Schjødt-Eriksen, Jens; Gaididei, Yuri Borisovich; Christiansen, Peter Leth

    2001-01-01

    Collapse of (2 + 1)-dimensional beams in the inhomogeneous two-dimensional cubic nonlinear Schrodinger equation is analyzed numerically and analytically. It is shown that in the vicinity of a narrow attractive inhomogeneity, the collapse of beams that in a homogeneous medium would collapse may...

  11. Phase transitions in two-dimensional systems

    International Nuclear Information System (INIS)

    Salinas, S.R.A.

    1983-01-01

    Some experiences are related using synchrotron radiation beams, to characterize solid-liquid (fusion) and commensurate solid-uncommensurate solid transitions in two-dimensional systems. Some ideas involved in the modern theories of two-dimensional fusion are shortly exposed. The systems treated consist of noble gases (Kr,Ar,Xe) adsorbed in the basal plane of graphite and thin films formed by some liquid crystal shells. (L.C.) [pt

  12. New indium selenite-oxalate and indium oxalate with two- and three-dimensional structures

    International Nuclear Information System (INIS)

    Cao Junjun; Li Guodong; Chen Jiesheng

    2009-01-01

    Two new indium(III) compounds with extended structures, [In 2 (SeO 3 ) 2 (C 2 O 4 )(H 2 O) 2 ].2H 2 O (I) and [NH 3 (CH 2 ) 2 NH 3 ][In(C 2 O 4 ) 2 ] 2 .5H 2 O (II), have been prepared under mild hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Compound I crystallizes in the triclinic system, space group P-1, with a=5.2596(11) A, b=6.8649(14) A, c=9.3289(19) A, α=101.78(3) o , β=102.03(3) o , γ=104.52(3) o , while compound II crystallizes in the orthorhombic system, space group Fdd2, with a=15.856(3) A, b=31.183(6) A, c=8.6688(17) A. In compound I, indium-selenite chains are bridged by oxalate units to form two-dimensional (2D) In 2 (SeO 3 ) 2 C 2 O 4 layers, separated by non-coordinating water molecules. In compound II, the indium atoms are connected through the oxalate units to generate a 3D open framework containing cross-linked 12- and 8-membered channels. - Graphical abstract: Two new indium(III) compounds have been hydrothermally synthesized and structurally characterized. In I, the indium-selenite chains are bridged by oxalate units to form 2D In 2 (SeO 3 ) 2 C 2 O 4 layers. In II, the indium atoms are connected through the oxalate units to generate a 3D open framework containing cross-linked 12- and 8-membered ring channels

  13. Two-dimensional Si nanosheets with local hexagonal structure on a MoS(2) surface.

    Science.gov (United States)

    Chiappe, Daniele; Scalise, Emilio; Cinquanta, Eugenio; Grazianetti, Carlo; van den Broek, Bas; Fanciulli, Marco; Houssa, Michel; Molle, Alessandro

    2014-04-02

    The structural and electronic properties of a Si nanosheet (NS) grown onto a MoS2 substrate by means of molecular beam epitaxy are assessed. Epitaxially grown Si is shown to adapt to the trigonal prismatic surface lattice of MoS2 by forming two-dimensional nanodomains. The Si layer structure is distinguished from the underlying MoS2 surface structure. The local electronic properties of the Si nanosheet are dictated by the atomistic arrangement of the layer and unlike the MoS2 hosting substrate they are qualified by a gap-less density of states. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Infrared emission of a freestanding plasmonic membrane

    Science.gov (United States)

    Monshat, Hosein; Liu, Longju; McClelland, John; Biswas, Rana; Lu, Meng

    2018-01-01

    This paper reports a free-standing plasmonic membrane as a thermal emitter in the near- and mid-infrared regions. The plasmonic membrane consists of an ultrathin gold film perforated with a two-dimensional array of holes. The device was fabricated using an imprint and transfer process and fixed on a low-emissivity metal grid. The thermal radiation characteristics of the plasmonic membrane can be engineered by controlling the array period and the thickness of the gold membrane. Plasmonic membranes with two different periods were designed using electromagnetic simulation and then characterized for their transmission and infrared radiation properties. The free-standing membranes exhibit extraordinary optical transmissions with the resonant transmission coefficient as high as 76.8%. After integration with a customized heater, the membranes demonstrate narrowband thermal emission in the wavelength range of 2.5 μm to 5.5 μm. The emission signatures, including peak emission wavelength and bandwidth, are associated with the membrane geometry. The ultrathin membrane infrared emitter can be adopted in applications, such as chemical analysis and thermal imaging.

  15. The theory of critical phenomena in two-dimensional systems

    International Nuclear Information System (INIS)

    Olvera de la C, M.

    1981-01-01

    An exposition of the theory of critical phenomena in two-dimensional physical systems is presented. The first six chapters deal with the mean field theory of critical phenomena, scale invariance of the thermodynamic functions, Kadanoff's spin block construction, Wilson's renormalization group treatment of critical phenomena in configuration space, and the two-dimensional Ising model on a triangular lattice. The second part of this work is made of four chapters devoted to the application of the ideas expounded in the first part to the discussion of critical phenomena in superfluid films, two-dimensional crystals and the two-dimensional XY model of magnetic systems. Chapters seven to ten are devoted to the following subjects: analysis of long range order in one, two, and three-dimensional physical systems. Topological defects in the XY model, in superfluid films and in two-dimensional crystals. The Thouless-Kosterlitz iterated mean field theory of the dipole gas. The renormalization group treatment of the XY model, superfluid films and two-dimensional crystal. (author)

  16. Two-dimensional profiling of Xanthomonas campestris pv. viticola ...

    African Journals Online (AJOL)

    However, the analysis of the 2D-PAGE gel images revealed a larger number of spots in the lysis method when compared to the others. Taking ... Keywords: Bacterial canker, Vitis vinifera, proteomics, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2D-PAGE).

  17. Dynamics of vortex interactions in two-dimensional flows

    DEFF Research Database (Denmark)

    Juul Rasmussen, J.; Nielsen, A.H.; Naulin, V.

    2002-01-01

    The dynamics and interaction of like-signed vortex structures in two dimensional flows are investigated by means of direct numerical solutions of the two-dimensional Navier-Stokes equations. Two vortices with distributed vorticity merge when their distance relative to their radius, d/R-0l. is below...... a critical value, a(c). Using the Weiss-field, a(c) is estimated for vortex patches. Introducing an effective radius for vortices with distributed vorticity, we find that 3.3 ... is effectively producing small scale structures and the relation to the enstrophy "cascade" in developed 2D turbulence is discussed. The influence of finite viscosity on the merging is also investigated. Additionally, we examine vortex interactions on a finite domain, and discuss the results in connection...

  18. Two-dimensional atom localization via Raman-driven coherence

    Energy Technology Data Exchange (ETDEWEB)

    Rahmatullah,; Qamar, Sajid, E-mail: sajid_qamar@comsats.edu.pk

    2014-02-07

    A scheme for two-dimensional (2D) atom localization via Raman-driven coherence in a four-level diamond-configuration system is suggested. The atom interacts with two orthogonal standing-wave fields where each standing-wave field is constructed from the superposition of the two-standing wave fields along the corresponding directions. Due to the position-dependent atom–field interaction, the frequency of the spontaneously emitted photon carries the position information about the atom. We investigate the effect of the detunings and phase shifts associated with standing-wave fields. Unique position information of the single atom is obtained by properly adjusting the system parameters. This is an extension of our previous proposal for one-dimensional atom localization via Raman-driven coherence.

  19. Tunneling between parallel two-dimensional electron liquids

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; MacDonald, A. H.

    361/362, - (1996), s. 167-170 ISSN 0039-6028. [International Conference on the Electronic Properties of Two Dimensional Systems /11./. Nottingham, 07.08.1995-11.08.1995] R&D Projects: GA ČR GA202/94/1278 Grant - others:INT(XX) 9106888 Impact factor: 2.783, year: 1996

  20. Half-metallic ferromagnetism prediction in MoS2-based two-dimensional superlattice from first-principles

    Science.gov (United States)

    Wen, Yan-Ni; Gao, Peng-Fei; Xia, Ming-Gang; Zhang, Sheng-Li

    2018-03-01

    Half-metallic ferromagnetism (HMFM) has great potential application in spin filter. However, it is extremely rare, especially in two-dimensional (2D) materials. At present, 2D materials have drawn international interest in spintronic devices. Here, we use ab initio density functional theory (DFT) calculations to study the structural stability and electrical and magnetic properties of the MoS2-based 2D superlattice formed by inserting graphene hexagonal ring in 6 × 6 × 1 MoS2 supercell. Two kinds of structures with hexagonal carbon ring were predicted with structural stability and were shown HMFM. The two structures combine the spin transport capacity of graphene with the magnetism of the defective 2D MoS2. And they have strong covalent bonding between the C and S or Mo atoms near the interface. This work is very useful to help us to design reasonable MoS2-based spin filter.

  1. Quasi-two-dimensional thermoelectricity in SnSe

    Science.gov (United States)

    Tayari, V.; Senkovskiy, B. V.; Rybkovskiy, D.; Ehlen, N.; Fedorov, A.; Chen, C.-Y.; Avila, J.; Asensio, M.; Perucchi, A.; di Pietro, P.; Yashina, L.; Fakih, I.; Hemsworth, N.; Petrescu, M.; Gervais, G.; Grüneis, A.; Szkopek, T.

    2018-01-01

    Stannous selenide is a layered semiconductor that is a polar analog of black phosphorus and of great interest as a thermoelectric material. Unusually, hole doped SnSe supports a large Seebeck coefficient at high conductivity, which has not been explained to date. Angle-resolved photoemission spectroscopy, optical reflection spectroscopy, and magnetotransport measurements reveal a multiple-valley valence-band structure and a quasi-two-dimensional dispersion, realizing a Hicks-Dresselhaus thermoelectric contributing to the high Seebeck coefficient at high carrier density. We further demonstrate that the hole accumulation layer in exfoliated SnSe transistors exhibits a field effect mobility of up to 250 cm2/V s at T =1.3 K . SnSe is thus found to be a high-quality quasi-two-dimensional semiconductor ideal for thermoelectric applications.

  2. Nonperturbative infrared dynamics in three dimensional QED

    International Nuclear Information System (INIS)

    Gusynin, V.P.

    2000-01-01

    A non-linear Schwinger-Dyson (SD) equation for the gauge boson propagator of massless QED in 2 + 1 dimensions is studied. It is shown that the nonperturbative solution leads to a non-trivial renormalization-group infrared fixed point quantitatively close to the one found in the leading order of the 1/N expansion, with N the number of fermion flavors

  3. Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

    2002-08-01

    Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

  4. Optimal Padding for the Two-Dimensional Fast Fourier Transform

    Science.gov (United States)

    Dean, Bruce H.; Aronstein, David L.; Smith, Jeffrey S.

    2011-01-01

    One-dimensional Fast Fourier Transform (FFT) operations work fastest on grids whose size is divisible by a power of two. Because of this, padding grids (that are not already sized to a power of two) so that their size is the next highest power of two can speed up operations. While this works well for one-dimensional grids, it does not work well for two-dimensional grids. For a two-dimensional grid, there are certain pad sizes that work better than others. Therefore, the need exists to generalize a strategy for determining optimal pad sizes. There are three steps in the FFT algorithm. The first is to perform a one-dimensional transform on each row in the grid. The second step is to transpose the resulting matrix. The third step is to perform a one-dimensional transform on each row in the resulting grid. Steps one and three both benefit from padding the row to the next highest power of two, but the second step needs a novel approach. An algorithm was developed that struck a balance between optimizing the grid pad size with prime factors that are small (which are optimal for one-dimensional operations), and with prime factors that are large (which are optimal for two-dimensional operations). This algorithm optimizes based on average run times, and is not fine-tuned for any specific application. It increases the amount of times that processor-requested data is found in the set-associative processor cache. Cache retrievals are 4-10 times faster than conventional memory retrievals. The tested implementation of the algorithm resulted in faster execution times on all platforms tested, but with varying sized grids. This is because various computer architectures process commands differently. The test grid was 512 512. Using a 540 540 grid on a Pentium V processor, the code ran 30 percent faster. On a PowerPC, a 256x256 grid worked best. A Core2Duo computer preferred either a 1040x1040 (15 percent faster) or a 1008x1008 (30 percent faster) grid. There are many industries that

  5. Dynamical observations on the crack tip zone and stress corrosion of two-dimensional MoS2

    KAUST Repository

    Ly, Thuc Hue

    2017-01-18

    Whether and how fracture mechanics needs to be modified for small length scales and in systems of reduced dimensionality remains an open debate. Here, employing in situ transmission electron microscopy, atomic structures and dislocation dynamics in the crack tip zone of a propagating crack in two-dimensional (2D) monolayer MoS2 membrane are observed, and atom-to-atom displacement mapping is obtained. The electron beam is used to initiate the crack; during in situ observation of crack propagation the electron beam effect is minimized. The observed high-frequency emission of dislocations is beyond previous understanding of the fracture of brittle MoS2. Strain analysis reveals dislocation emission to be closely associated with the crack propagation path in nanoscale. The critical crack tip plastic zone size of nearly perfect 2D MoS2 is between 2 and 5 nm, although it can grow to 10 nm under corrosive conditions such as ultraviolet light exposure, showing enhanced dislocation activity via defect generation.

  6. Quasi-Two-Dimensional h-BN/β-Ga2O3 Heterostructure Metal-Insulator-Semiconductor Field-Effect Transistor.

    Science.gov (United States)

    Kim, Janghyuk; Mastro, Michael A; Tadjer, Marko J; Kim, Jihyun

    2017-06-28

    β-gallium oxide (β-Ga 2 O 3 ) and hexagonal boron nitride (h-BN) heterostructure-based quasi-two-dimensional metal-insulator-semiconductor field-effect transistors (MISFETs) were demonstrated by integrating mechanical exfoliation of (quasi)-two-dimensional materials with a dry transfer process, wherein nanothin flakes of β-Ga 2 O 3 and h-BN were utilized as the channel and gate dielectric, respectively, of the MISFET. The h-BN dielectric, which has an extraordinarily flat and clean surface, provides a minimal density of charged impurities on the interface between β-Ga 2 O 3 and h-BN, resulting in superior device performances (maximum transconductance, on/off ratio, subthreshold swing, and threshold voltage) compared to those of the conventional back-gated configurations. Also, double-gating of the fabricated device was demonstrated by biasing both top and bottom gates, achieving the modulation of the threshold voltage. This heterostructured wide-band-gap nanodevice shows a new route toward stable and high-power nanoelectronic devices.

  7. Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

    DEFF Research Database (Denmark)

    Tang, Yingying; Cao, Xianyi; Chi, Qijin

    2018-01-01

    Compared to their conventional three-dimensional (3D) counterparts, two-dimensional (2D) halide perovskites have attracted more interests recently in a variety of areas related to optoelectronics because of their unique structural characteristics and enhanced performances. In general, there are two...... distinct types of 2D halide perovskites. One represents those perovskites with an intrinsic layered crystal structure (i.e. MX6 layers, M = metal and X = Cl, Br, I), the other defines the perovskites with a 2D nanostructured morphology such as nanoplatelets and nanosheets. Recent studies have shown that 2D...... halide perovskites hold promising potential for the development of new-generation photodetectors, mainly arising from their highly efficient photoluminescence and absorbance, color tunability in the visible-light range and relatively high stability. In this chapter, we present the summary and highlights...

  8. Two dimensional MoS{sub 2}/graphene p-n heterojunction diode: Fabrication and electronic characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wei-Jhih [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Chang, Hsuan-Chen [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Wang, Yi-Ping [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Hsu, Hung-Pin [Department of Electronic Engineering, Ming Chi University of Technology, 84 Gungjuan Road, New Taipei City 24301, Taiwan (China); Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2016-06-25

    Molybdenum disulfide (MoS{sub 2}) films are currently the most potential semiconductor materials of the two-dimensional nano-material heterojunction. Few-layer MoS{sub 2} is an n-type semiconductor that has good mechanical strength, high carrier mobility, and has similar thickness as graphene. Graphene is presently the thinnest two-dimensional material with good thermal conductivity and high carrier mobility. The graphene Fermi level can be precisely controlled using the oxygen adsorption. Therefore, graphene can be tuned from zero-gap to p-type semiconductor material using the amount of adsorbed oxygen. In this study we combine few-layer MoS{sub 2} and graphene to produce a heterojunction and exhaustively study the interface properties for heterojunction diode application. According to the results, the MoS{sub 2} band-gap increases with decreasing thickness. The I–V characteristics of the MoS{sub 2}/Graphene p-n junction diodes can be precisely tuned by adjusting different thicknesses of the MoS{sub 2} films. By applying our fabricating method, MoS{sub 2}/Graphene heterojunction diode can be easily constructed and have potential to different applications. - Highlights: • We controlled the layer thickness of MoS{sub 2} by different exfoliation times. • We presented Raman scattering of MoS{sub 2} and define their layers number. • The few-layer MoS{sub 2}/graphene pn junction diode was synthesized. • We measured the device current and voltage characteristics. • The built-in potential barrier could be adjusted by controlling MoS{sub 2} thicknesses.

  9. Mass spectrum of the two dimensional lambdaphi4-1/4phi2-μphi quantum field model

    International Nuclear Information System (INIS)

    Imbrie, J.Z.

    1980-01-01

    It is shown that r-particle irreducible kernels in the two-dimensional lambdaphi 4 -1/4phi 2 -μphi quantum field theory have (r+1)-particle decay for vertical stroke μ vertical stroke 2 << 1. As a consequence there is an upper mass gap and, in the subspace of two-particle states, a bound state. The proof extends Spencer's expansion to handle fluctuations between the two wells of the classical potential. A new method for resumming the low temperature cluster expansion is introduced. (orig.)

  10. Three-dimensional versus two-dimensional vision in laparoscopy

    DEFF Research Database (Denmark)

    Sørensen, Stine D; Savran, Mona Meral; Konge, Lars

    2016-01-01

    were cohort size and characteristics, skill trained or operation performed, instrument used, outcome measures, and conclusions. Two independent authors performed the search and data extraction. RESULTS: Three hundred and forty articles were screened for eligibility, and 31 RCTs were included...... through a two-dimensional (2D) projection on a monitor, which results in loss of depth perception. To counter this problem, 3D imaging for laparoscopy was developed. A systematic review of the literature was performed to assess the effect of 3D laparoscopy. METHODS: A systematic search of the literature...... in the review. Three trials were carried out in a clinical setting, and 28 trials used a simulated setting. Time was used as an outcome measure in all of the trials, and number of errors was used in 19 out of 31 trials. Twenty-two out of 31 trials (71 %) showed a reduction in performance time, and 12 out of 19...

  11. From Soft Walls to Infrared Branes

    CERN Document Server

    von Gersdorff, Gero

    2010-01-01

    Five dimensional warped spaces with soft walls are generalizations of the standard Randall-Sundrum compactifications, where instead of an infrared brane one has a curvature singularity (with vanishing warp factor) at finite proper distance in the bulk. We project the physics near the singularity onto a hypersurface located a small distance away from it in the bulk. This results in a completely equivalent description of the soft wall in terms of an effective infrared brane, hiding any singular point. We perform explicitly this calculation for two classes of soft wall backgrounds used in the literature. The procedure has several advantages. It separates in a clean way the physics of the soft wall from the physics of the five dimensional bulk, facilitating a more direct comparison with standard two-brane warped compactifications. Moreover, consistent soft walls show a sort of universal behavior near the singularity which is reflected in the effective brane Lagrangian. Thirdly, for many purposes, a good approxima...

  12. String vacuum backgrounds with covariantly constant null Killing vector and two-dimensional quantum gravity

    International Nuclear Information System (INIS)

    Tseytlin, A.A.

    1993-01-01

    We consider a two-dimensional sigma model with a (2+N)-dimensional Minkowski signature target space metric having a covariantly constant null Killing vector. We study solutions of the conformal invariance conditions in 2+N dimensions and find that generic solutions can be represented in terms of the RG flow in N-dimensional 'transverse space' theory. The resulting conformal invariant sigma model is interpreted as a quantum action of the two-dimensional scalar ('dilaton') quantum gravity model coupled to a (non-conformal) 'transverse' sigma model. The conformal factor of the two-dimensional metric is identified with a light-cone coordinate of the (2+N)-dimensional sigma model. We also discuss the case when the transverse theory is conformal (with or without the antisymmetric tensor background) and reproduce in a systematic way the solutions with flat transverse space known before. (orig.)

  13. Principal Component Analysis Based Two-Dimensional (PCA-2D) Correlation Spectroscopy: PCA Denoising for 2D Correlation Spectroscopy

    International Nuclear Information System (INIS)

    Jung, Young Mee

    2003-01-01

    Principal component analysis based two-dimensional (PCA-2D) correlation analysis is applied to FTIR spectra of polystyrene/methyl ethyl ketone/toluene solution mixture during the solvent evaporation. Substantial amount of artificial noise were added to the experimental data to demonstrate the practical noise-suppressing benefit of PCA-2D technique. 2D correlation analysis of the reconstructed data matrix from PCA loading vectors and scores successfully extracted only the most important features of synchronicity and asynchronicity without interference from noise or insignificant minor components. 2D correlation spectra constructed with only one principal component yield strictly synchronous response with no discernible a asynchronous features, while those involving at least two or more principal components generated meaningful asynchronous 2D correlation spectra. Deliberate manipulation of the rank of the reconstructed data matrix, by choosing the appropriate number and type of PCs, yields potentially more refined 2D correlation spectra

  14. Two- and three-dimensional CT analysis of ankle fractures

    International Nuclear Information System (INIS)

    Magid, D.; Fishman, E.K.; Ney, D.R.; Kuhlman, J.E.

    1988-01-01

    CT with coronal and sagittal reformatting (two-dimensional CT) and animated volumetric image rendering (three-dimensional CT) was used to assess ankle fractures. Partial volume limits transaxial CT in assessments of horizontally oriented structures. Two-dimensional CT, being orthogonal to the plafond, superior mortise, talar dome, and tibial epiphysis, often provides the most clinically useful images. Two-dimensional CT is most useful in characterizing potentially confusing fractures, such as Tillaux (anterior tubercle), triplane, osteochondral talar dome, or nondisplaced talar neck fractures, and it is the best study to confirm intraarticular fragments. Two-and three-dimensional CT best indicate the percentage of articular surface involvement and best demonstrate postoperative results or complications (hardware migration, residual step-off, delayed union, DJD, AVN, etc). Animated three-dimensional images are the preferred means of integrating the two-dimensional findings for surgical planning, as these images more closely simulate the clinical problem

  15. On two-dimensionalization of three-dimensional turbulence in shell models

    DEFF Research Database (Denmark)

    Chakraborty, Sagar; Jensen, Mogens Høgh; Sarkar, A.

    2010-01-01

    Applying a modified version of the Gledzer-Ohkitani-Yamada (GOY) shell model, the signatures of so-called two-dimensionalization effect of three-dimensional incompressible, homogeneous, isotropic fully developed unforced turbulence have been studied and reproduced. Within the framework of shell m......-similar PDFs for longitudinal velocity differences are also presented for the rotating 3D turbulence case....

  16. Two-dimensional turbulent convection

    Science.gov (United States)

    Mazzino, Andrea

    2017-11-01

    We present an overview of the most relevant, and sometimes contrasting, theoretical approaches to Rayleigh-Taylor and mean-gradient-forced Rayleigh-Bénard two-dimensional turbulence together with numerical and experimental evidences for their support. The main aim of this overview is to emphasize that, despite the different character of these two systems, especially in relation to their steadiness/unsteadiness, turbulent fluctuations are well described by the same scaling relationships originated from the Bolgiano balance. The latter states that inertial terms and buoyancy terms balance at small scales giving rise to an inverse kinetic energy cascade. The main difference with respect to the inverse energy cascade in hydrodynamic turbulence [R. H. Kraichnan, "Inertial ranges in two-dimensional turbulence," Phys. Fluids 10, 1417 (1967)] is that the rate of cascade of kinetic energy here is not constant along the inertial range of scales. Thanks to the absence of physical boundaries, the two systems here investigated turned out to be a natural physical realization of the Kraichnan scaling regime hitherto associated with the elusive "ultimate state of thermal convection" [R. H. Kraichnan, "Turbulent thermal convection at arbitrary Prandtl number," Phys. Fluids 5, 1374-1389 (1962)].

  17. Two-dimensional structure of poly[[[μ2-1,4-bis(pyridin-4-ylbutane]bis(μ4-pentanedioatodicopper(II] acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Do Nam Lee

    2017-10-01

    Full Text Available In the title compound, {[Cu2(μ4-C5H6O42(μ2-C14H16N22CH3CN}n, the Cu2 dinuclear units are connected by glutartate ligands, forming one-dimensional double chains. These chains, are in turn bridged by 1,4-bis(pyridin-4-ylbutane ligands to form a two-dimensional layer structure parallel to (112. The carboxylate groups of the glutarate ligand bridge two copper(II ions, forming a paddle-wheel-type Cu2(CO24 dinuclear secondary building unit. A crystallographic inversion centre is located midway between two CuII ions, with a Cu...Cu distance of 2.639 (3 Å. The coordination geometry of the unique CuII ion is slightly disorted square pyramidal, formed by four equatorial carboxylate O atoms and an axial pyridyl N atom.

  18. On final states of two-dimensional decaying turbulence

    NARCIS (Netherlands)

    Yin, Z.

    2004-01-01

    Numerical and analytical studies of final states of two-dimensional (2D) decaying turbulence are carried out. The first part of this work is trying to give a definition for final states of 2D decaying turbulence. The functional relation of ¿-¿, which is frequently adopted as the characterization of

  19. Magnetic structure of two- and three-dimensional supramolecular compounds

    Energy Technology Data Exchange (ETDEWEB)

    Decurtins, S.; Schmalle, H.W.; Pellaux, R. [Zurich Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    Supramolecular chiral networks of oxalato-bridged transition metals show either two- or three-dimensional structural features. The magnetic structures of such compounds have been investigated by means of elastic neutron powder diffraction. (author) 2 figs., 2 refs.

  20. Two dimensional layered materials: First-principle investigation

    Science.gov (United States)

    Tang, Youjian

    Two-dimensional layered materials have emerged as a fascinating research area due to their unique physical and chemical properties, which differ from those of their bulk counterparts. Some of these unique properties are due to carriers and transport being confined to 2 dimensions, some are due to lattice symmetry, and some arise from their large surface area, gateability, stackability, high mobility, spin transport, or optical accessibility. How to modify the electronic and magnetic properties of two-dimensional layered materials for desirable long-term applications or fundamental physics is the main focus of this thesis. We explored the methods of adsorption, intercalation, and doping as ways to modify two-dimensional layered materials, using density functional theory as the main computational methodology. Chapter 1 gives a brief review of density functional theory. Due to the difficulty of solving the many-particle Schrodinger equation, density functional theory was developed to find the ground-state properties of many-electron systems through an examination of their charge density, rather than their wavefunction. This method has great application throughout the chemical and material sciences, such as modeling nano-scale systems, analyzing electronic, mechanical, thermal, optical and magnetic properties, and predicting reaction mechanisms. Graphene and transition metal dichalcogenides are arguably the two most important two-dimensional layered materials in terms of the scope and interest of their physical properties. Thus they are the main focus of this thesis. In chapter 2, the structure and electronic properties of graphene and transition metal dichalcogenides are described. Alkali adsorption onto the surface of bulk graphite and metal intecalation into transition metal dichalcogenides -- two methods of modifying properties through the introduction of metallic atoms into layered systems -- are described in chapter 2. Chapter 3 presents a new method of tuning

  1. Warranty menu design for a two-dimensional warranty

    International Nuclear Information System (INIS)

    Ye, Zhi-Sheng; Murthy, D.N. Pra

    2016-01-01

    Fierce competitions in the commercial product market have forced manufacturers to provide customer-friendly warranties with a view to achieving higher customer satisfaction and increasing the market share. This study proposes a strategy that offers customers a two-dimensional warranty menu with a number of warranty choices, called a flexible warranty policy. We investigate the design of a flexible two-dimensional warranty policy that contains a number of rectangular regions. This warranty policy is obtained by dividing customers into several groups according to their use rates and providing each group a germane warranty region. Consumers choose a favorable one from the menu according to their usage behaviors. Evidently, this flexible warranty policy is attractive to users of different usage behaviors, and thus, it gives the manufacturer a good position in advertising the product. When consumers are unaware about their use rates upon purchase, we consider a fixed two-dimensional warranty policy with a stair-case warranty region and show that it is equivalent to the flexible policy. Such an equivalence reveals the inherent relationship between the rectangular warranty policy, the L-shape warranty policy, the step-stair warranty policy and the iso-probability of failure warranty policy that were extensively discussed in the literature. - Highlights: • We design a two-dimensional warranty menu with a number of warranty choices. • Consumers can choose a favorable one from the menu as per their usage behavior. • We further consider a fixed 2D warranty policy with a stair-case warranty region. • We show the equivalence of the two warranty policies.

  2. Additive Manufacturing Infrared Inspection

    Science.gov (United States)

    Gaddy, Darrell; Nettles, Mindy

    2015-01-01

    The Additive Manufacturing Infrared Inspection Task started the development of a real-time dimensional inspection technique and digital quality record for the additive manufacturing process using infrared camera imaging and processing techniques. This project will benefit additive manufacturing by providing real-time inspection of internal geometry that is not currently possible and reduce the time and cost of additive manufactured parts with automated real-time dimensional inspections which deletes post-production inspections.

  3. FX2-TH: a two-dimensional nuclear reactor kinetics code with thermal-hydraulic feedback

    International Nuclear Information System (INIS)

    Shober, R.A.; Daly, T.A.; Ferguson, D.R.

    1978-10-01

    FX2-TH is a two-dimensional, time-dependent nuclear reactor kinetics program with thermal and hydraulic feedback. The neutronics model used is multigroup neutron diffusion theory. The following geometry options are available: x, r, x-y, r-z, theta-r, and triangular. FX2-TH contains two basic thermal and hydraulic models: a simple adiabatic fuel temperature calculation, and a more detailed model consisting of an explicit representation of a fuel pin, gap, clad, and coolant. FX2-TH allows feedback effects from both fuel temperature (Doppler) and coolant temperature (density) changes. FX2-TH will calculate a consistent set of steady state conditions by iterating between the neutronics and thermal-hydraulics until convergence is reached. The time-dependent calculation is performed by the use of the improved quasistatic method. A disk editing capability is available. FX2-TH is operational on IBM system 360 or 370 computers and on the CDC 7600

  4. THE INFRARED PROPERTIES OF EMBEDDED SUPER STAR CLUSTERS: PREDICTIONS FROM THREE-DIMENSIONAL RADIATIVE TRANSFER MODELS

    International Nuclear Information System (INIS)

    Whelan, David G.; Johnson, Kelsey E.; Indebetouw, Remy; Whitney, Barbara A.; Wood, Kenneth

    2011-01-01

    With high-resolution infrared data becoming available that can probe the formation of high-mass stellar clusters for the first time, appropriate models that make testable predictions of these objects are necessary. We utilize a three-dimensional radiative transfer code, including a hierarchically clumped dusty envelope, to study the earliest stages of super star cluster (SSC) evolution. We explore a range of parameter space in geometric sequences that mimic the hypothesized evolution of an embedded SSC. The inclusion of a hierarchically clumped medium can make the envelope porous, in accordance with previous models and supporting observational evidence. The infrared luminosity inferred from observations can differ by a factor of two from the true value in the clumpiest envelopes depending on the viewing angle. The infrared spectral energy distribution also varies with viewing angle for clumpy envelopes, creating a range in possible observable infrared colors and magnitudes, silicate feature depths, and dust continua. General observable features of cluster evolution differ between envelopes that are relatively opaque or transparent to mid-infrared photons. For optically thick envelopes, evolution is marked by a gradual decline of the 9.8 μm silicate absorption feature depth and a corresponding increase in the visual/ultraviolet flux. For the optically thin envelopes, clusters typically begin with a strong hot dust component and silicates in emission, and these features gradually fade until the mid-infrared polycyclic aromatic hydrocarbon features are predominant. For the models with a smooth dust distribution, the Spitzer MIPS or Herschel PACS [70]-[160] color is a good probe of the stellar mass relative to the total mass or star formation efficiency (SFE). Likewise, the IRAC/MIPS [3.6]-[24] color can be used to constrain the R in and R out values of the envelope. However, clumpiness confuses the general trends seen in the smooth dust distribution models, making it

  5. Infrared studies of two dark clouds

    International Nuclear Information System (INIS)

    Elias, J.H.

    1978-01-01

    The IC5146 dark cloud complex was surveyed in the infrared in order to identify and study associated young stellar objects. Most of the objects detected in the survey appears to be field stars, predominantly late-type giants. Three young objects were detected in the survey: the BO star BD + 46 x 3474, the Ae star BD + 46 x 3471, and a previously unidentified object which appear to be a heavily obscured FU Ori star. The properties of the last two objects are examined in detail, and an attempt is made to produce reasonable models for them. It is suggested that FU Ori stars are binaries, and some consequences of this model are described. Photometry of the brighter stars in the IC5146 cluster was used to establish a distance to the cluster of 900 +- 100 pc. A near-infrared survey was also conducted of nearly 18 square degrees of the Ophiuchus dark cloud complex. Additional observations were made of selected objects found in this region, in order to identify and study the young stars associated with the cloud. These observations show that very recent star formation has been largely restricted to a small region no more than a few parsecs in extent at the center of the dark cloud complex. Most of the young stars do not appear to be main sequence stars. At least three of these objects appear to be surrounded by infrared reflection nebulae. Many of the objects studies are background K and M giants which can be used to determine the near-infrared extinction due to the dark cloud

  6. Multi-perspective views of students’ difficulties with one-dimensional vector and two-dimensional vector

    Science.gov (United States)

    Fauzi, Ahmad; Ratna Kawuri, Kunthi; Pratiwi, Retno

    2017-01-01

    Researchers of students’ conceptual change usually collects data from written tests and interviews. Moreover, reports of conceptual change often simply refer to changes in concepts, such as on a test, without any identification of the learning processes that have taken place. Research has shown that students have difficulties with vectors in university introductory physics courses and high school physics courses. In this study, we intended to explore students’ understanding of one-dimensional and two-dimensional vector in multi perspective views. In this research, we explore students’ understanding through test perspective and interviews perspective. Our research study adopted the mixed-methodology design. The participants of this research were sixty students of third semester of physics education department. The data of this research were collected by testand interviews. In this study, we divided the students’ understanding of one-dimensional vector and two-dimensional vector in two categories, namely vector skills of the addition of one-dimensionaland two-dimensional vector and the relation between vector skills and conceptual understanding. From the investigation, only 44% of students provided correct answer for vector skills of the addition of one-dimensional and two-dimensional vector and only 27% students provided correct answer for the relation between vector skills and conceptual understanding.

  7. Optimizing separations in online comprehensive two-dimensional liquid chromatography.

    Science.gov (United States)

    Pirok, Bob W J; Gargano, Andrea F G; Schoenmakers, Peter J

    2018-01-01

    Online comprehensive two-dimensional liquid chromatography has become an attractive option for the analysis of complex nonvolatile samples found in various fields (e.g. environmental studies, food, life, and polymer sciences). Two-dimensional liquid chromatography complements the highly popular hyphenated systems that combine liquid chromatography with mass spectrometry. Two-dimensional liquid chromatography is also applied to the analysis of samples that are not compatible with mass spectrometry (e.g. high-molecular-weight polymers), providing important information on the distribution of the sample components along chemical dimensions (molecular weight, charge, lipophilicity, stereochemistry, etc.). Also, in comparison with conventional one-dimensional liquid chromatography, two-dimensional liquid chromatography provides a greater separation power (peak capacity). Because of the additional selectivity and higher peak capacity, the combination of two-dimensional liquid chromatography with mass spectrometry allows for simpler mixtures of compounds to be introduced in the ion source at any given time, improving quantitative analysis by reducing matrix effects. In this review, we summarize the rationale and principles of two-dimensional liquid chromatography experiments, describe advantages and disadvantages of combining different selectivities and discuss strategies to improve the quality of two-dimensional liquid chromatography separations. © 2017 The Authors. Journal of Separation Science published by WILEY-VCH Verlag GmbH & Co. KGaA.

  8. The simulation of a two-dimensional (2D) transport problem in a rectangular region with Lattice Boltzmann method with two-relaxation-time

    Science.gov (United States)

    Sugiyanto, S.; Hardyanto, W.; Marwoto, P.

    2018-03-01

    Transport phenomena are found in many problems in many engineering and industrial sectors. We analyzed a Lattice Boltzmann method with Two-Relaxation Time (LTRT) collision operators for simulation of pollutant moving through the medium as a two-dimensional (2D) transport problem in a rectangular region model. This model consists of a 2D rectangular region with 54 length (x), 27 width (y), and it has isotropic homogeneous medium. Initially, the concentration is zero and is distributed evenly throughout the region of interest. A concentration of 1 is maintained at 9 < y < 18, whereas the concentration of zero is maintained at 0 < y < 9 and 18 < y < 27. A specific discharge (Darcy velocity) of 1.006 is assumed. A diffusion coefficient of 0.8333 is distributed uniformly with a uniform porosity of 0.35. A computer program is written in MATLAB to compute the concentration of pollutant at any specified place and time. The program shows that LTRT solution with quadratic equilibrium distribution functions (EDFs) and relaxation time τa=1.0 are in good agreement result with other numerical solutions methods such as 3DLEWASTE (Hybrid Three-dimensional Lagrangian-Eulerian Finite Element Model of Waste Transport Through Saturated-Unsaturated Media) obtained by Yeh and 3DFEMWATER-LHS (Three-dimensional Finite Element Model of Water Flow Through Saturated-Unsaturated Media with Latin Hypercube Sampling) obtained by Hardyanto.

  9. Binding energy of two-dimensional biexcitons

    DEFF Research Database (Denmark)

    Singh, Jai; Birkedal, Dan; Vadim, Lyssenko

    1996-01-01

    Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....

  10. Second invariant for two-dimensional classical super systems

    Indian Academy of Sciences (India)

    Construction of superpotentials for two-dimensional classical super systems (for N. 2) is carried ... extensively used for the case of non-linear partial differential equation by various authors. [3,4–7,12 ..... found to be integrable just by accident.

  11. Spin-Dependent Scattering Effects and Dimensional Crossover in a Quasi-Two-Dimensional Disordered Electron System

    Institute of Scientific and Technical Information of China (English)

    YANG YongHong; WANG YongGang; LIU Mei; WANG Jin

    2002-01-01

    Two kinds of spin-depcndcnt scattering effects (magnetic-iinpurity and spin-orbit scatterings) axe investi-gated theoretically in a quasi-two-dimensional (quasi-2D) disordered electron system. By making use of the diagrammatictechniques in perturbation theory, we have calculated the dc conductivity and magnetoresistance due to weak-localizationeffects, the analytical expressions of them are obtained as functions of the interlayer hopping energy and the charac-teristic times: elastic, inelastic, magnetic and spin-orbit scattering times. The relevant dimensional crossover behaviorfrom 3D to 2D with decreasing the interlayer coupling is discussed, and the condition for the crossover is shown to bedependent on the aforementioned scattering times. At low temperature there exists a spin-dcpendent-scattering-induccddimensional crossover in this system.

  12. Two-dimensional multiferroics in monolayer group IV monochalcogenides

    Science.gov (United States)

    Wang, Hua; Qian, Xiaofeng

    2017-03-01

    Low-dimensional multiferroic materials hold great promises in miniaturized device applications such as nanoscale transducers, actuators, sensors, photovoltaics, and nonvolatile memories. Here, using first-principles theory we predict that two-dimensional (2D) monolayer group IV monochalcogenides including GeS, GeSe, SnS, and SnSe are a class of 2D semiconducting multiferroics with giant strongly-coupled in-plane spontaneous ferroelectric polarization and spontaneous ferroelastic lattice strain that are thermodynamically stable at room temperature and beyond, and can be effectively modulated by elastic strain engineering. Their optical absorption spectra exhibit strong in-plane anisotropy with visible-spectrum excitonic gaps and sizable exciton binding energies, rendering the unique characteristics of low-dimensional semiconductors. More importantly, the predicted low domain wall energy and small migration barrier together with the coupled multiferroic order and anisotropic electronic structures suggest their great potentials for tunable multiferroic functional devices by manipulating external electrical, mechanical, and optical field to control the internal responses, and enable the development of four device concepts including 2D ferroelectric memory, 2D ferroelastic memory, and 2D ferroelastoelectric nonvolatile photonic memory as well as 2D ferroelectric excitonic photovoltaics.

  13. Two-dimensional liquid chromatography

    DEFF Research Database (Denmark)

    Græsbøll, Rune

    -dimensional separation space. Optimization of gradients in online RP×RP is more difficult than in normal HPLC as a result of the increased number of parameters and their influence on each other. Modeling the coverage of the compounds across the two-dimensional chromatogram as a result of a change in gradients could...... be used for optimization purposes, and reduce the time spend on optimization. In this thesis (chapter 6), and manuscript B, a measure of the coverage of the compounds in the twodimensional separation space is defined. It is then shown that this measure can be modeled for changes in the gradient in both...

  14. Two-dimensional simulation of sintering process

    International Nuclear Information System (INIS)

    Vasconcelos, Vanderley de; Pinto, Lucio Carlos Martins; Vasconcelos, Wander L.

    1996-01-01

    The results of two-dimensional simulations are directly applied to systems in which one of the dimensions is much smaller than the others, and to sections of three dimensional models. Moreover, these simulations are the first step of the analysis of more complex three-dimensional systems. In this work, two basic features of the sintering process are studied: the types of particle size distributions related to the powder production processes and the evolution of geometric parameters of the resultant microstructures during the solid-state sintering. Random packing of equal spheres is considered in the sintering simulation. The packing algorithm does not take into account the interactive forces between the particles. The used sintering algorithm causes the densification of the particle set. (author)

  15. Three New (2+1)-dimensional Integrable Systems and Some Related Darboux Transformations

    International Nuclear Information System (INIS)

    Guo Xiu-Rong

    2016-01-01

    We introduce two operator commutators by using different-degree loop algebras of the Lie algebra A 1 , then under the framework of zero curvature equations we generate two (2+1)-dimensional integrable hierarchies, including the (2+1)-dimensional shallow water wave (SWW) hierarchy and the (2+1)-dimensional Kaup-Newell (KN) hierarchy. Through reduction of the (2+1)-dimensional hierarchies, we get a (2+1)-dimensional SWW equation and a (2+1)-dimensional KN equation. Furthermore, we obtain two Darboux transformations of the (2+1)-dimensional SWW equation. Similarly, the Darboux transformations of the (2+1)-dimensional KN equation could be deduced. Finally, with the help of the spatial spectral matrix of SWW hierarchy, we generate a (2+1) heat equation and a (2+1) nonlinear generalized SWW system containing inverse operators with respect to the variables x and y by using a reduction spectral problem from the self-dual Yang-Mills equations. (paper)

  16. Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy.

    Science.gov (United States)

    Jin, Yuwei; Cristescu, Simona M; Harren, Frans J M; Mandon, Julien

    2014-06-01

    We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250  cm(-1) within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000  cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.

  17. Highly mobile charge-transfer excitons in two-dimensional WS2/tetracene heterostructures

    Science.gov (United States)

    Zhu, Tong; Yuan, Long; Zhao, Yan; Zhou, Mingwei; Wan, Yan; Mei, Jianguo; Huang, Libai

    2018-01-01

    Charge-transfer (CT) excitons at heterointerfaces play a critical role in light to electricity conversion using organic and nanostructured materials. However, how CT excitons migrate at these interfaces is poorly understood. We investigate the formation and transport of CT excitons in two-dimensional WS2/tetracene van der Waals heterostructures. Electron and hole transfer occurs on the time scale of a few picoseconds, and emission of interlayer CT excitons with a binding energy of ~0.3 eV has been observed. Transport of the CT excitons is directly measured by transient absorption microscopy, revealing coexistence of delocalized and localized states. Trapping-detrapping dynamics between the delocalized and localized states leads to stretched-exponential photoluminescence decay with an average lifetime of ~2 ns. The delocalized CT excitons are remarkably mobile with a diffusion constant of ~1 cm2 s−1. These highly mobile CT excitons could have important implications in achieving efficient charge separation. PMID:29340303

  18. Equatorial spread F studies using SAMI3 with two-dimensional and three-dimensional electrostatics

    Directory of Open Access Journals (Sweden)

    H. C. Aveiro

    2013-12-01

    Full Text Available This letter presents a study of equatorial F region irregularities using the NRL SAMI3/ESF model, comparing results using a two-dimensional (2-D and a three-dimensional (3-D electrostatic potential solution. For the 3-D potential solution, two cases are considered for parallel plasma transport: (1 transport based on the parallel ambipolar field, and (2 transport based on the parallel electric field. The results show that the growth rate of the generalized Rayleigh–Taylor instability is not affected by the choice of the potential solution. However, differences are observed in the structures of the irregularities between the 2-D and 3-D solutions. Additionally, the plasma velocity along the geomagnetic field computed using the full 3-D solution shows complex structures that are not captured by the simplified model. This points out that only the full 3-D model is able to fully capture the complex physics of the equatorial F region.

  19. Crystal structure of a two-dimensional grid-type iron(II coordination polymer: poly[[diaquatetra-μ-cyanido-diargentate(Iiron(II] trans-1,2-bis(pyridin-2-ylethylene disolvate

    Directory of Open Access Journals (Sweden)

    Jintana Othong

    2014-08-01

    Full Text Available In the title compound, {[Ag2Fe(CN4(H2O22C12H10N2}n, the asymmetric unit contains one FeII cation, two water molecules, two dicyanidoargentate(I anions and two uncoordinating 1,2-bis(pyridin-2-ylethylene (2,2′-bpe molecules. Each FeII atom is six-coordinated in a nearly regular octahedral geometry by four N atoms from dicyanidoargentate(I bridges and two coordinating water molecules. The FeII atoms are bridged by dicyanidoargentate(I units to give a two-dimensional layer with square-grid spaces. The intergrid spaces with interlayer distance of 6.550 (2 Å are occupied by 2,2′-bpe guest molecules which form O—H...N hydrogen bonds to the host layers. This leads to an extended three-dimensional supramolecular architecture. The structure of the title compound is compared with some related compounds containing dicyanidoargentate(I ligands and N-donor organic co-ligands.

  20. Driving performance of a two-dimensional homopolar linear DC motor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Yamaguchi, M.; Kano, Y. [Tokyo University of Agriculture and Technology, Tokyo (Japan)

    1998-05-01

    This paper presents a novel two-dimensional homopolar linear de motor (LDM) which can realize two-dimensional (2-D) motion. For position control purposes, two kinds of position detecting methods are proposed. The position in one position is detected by means of a capacitive sensor which makes the output of the sensor partially immune to the variation of the gap between electrodes. The position in the other direction is achieved by exploiting the position dependent property of the driving coil inductance, instead of using an independent sensor. The position control is implemented on the motor and 2-D tracking performance is analyzed. Experiments show that the motor demonstrates satisfactory driving performance, 2-D tracking error being within 5.5% when the angular frequency of reference signal is 3.14 rad./s. 7 refs., 17 figs., 2 tabs.

  1. Two-Dimensional Homogeneous Fermi Gases

    Science.gov (United States)

    Hueck, Klaus; Luick, Niclas; Sobirey, Lennart; Siegl, Jonas; Lompe, Thomas; Moritz, Henning

    2018-02-01

    We report on the experimental realization of homogeneous two-dimensional (2D) Fermi gases trapped in a box potential. In contrast to harmonically trapped gases, these homogeneous 2D systems are ideally suited to probe local as well as nonlocal properties of strongly interacting many-body systems. As a first benchmark experiment, we use a local probe to measure the density of a noninteracting 2D Fermi gas as a function of the chemical potential and find excellent agreement with the corresponding equation of state. We then perform matter wave focusing to extract the momentum distribution of the system and directly observe Pauli blocking in a near unity occupation of momentum states. Finally, we measure the momentum distribution of an interacting homogeneous 2D gas in the crossover between attractively interacting fermions and bosonic dimers.

  2. A Dirac-Kaehler approach to the two dimensional Wess-Zumino N=2 model on the lattice

    International Nuclear Information System (INIS)

    Zimerman, A.H.; Aratyn, H.

    1983-08-01

    We introduce a Dirac-Kaehler model for the two dimensional Wess-Zumino N=2 Lagrangean. We can show that in the model, when we go to the euclidean space-time lattive, we have no energy doubling, the action has no lattice surface terms (contrary to other authors), while the Hamiltonians (when time is continuous) present lattice surface terms. (orig.)

  3. Image Making in Two Dimensional Art; Experiences with Straw and ...

    African Journals Online (AJOL)

    Image making in art is professionally referred to as bust in Sculpture andPortraiture in Painting. It is an art form executed in three dimensional (3D)and two dimensional (2D) formats respectively. Uncountable materials havebeen used to achieve these forms of art; like clay cement, marble, stone,different metals and, fibre ...

  4. Chaotic dynamics in two-dimensional noninvertible maps

    CERN Document Server

    Mira, Christian; Cathala, Jean-Claude; Gardini, Laura

    1996-01-01

    This book is essentially devoted to complex properties (Phase plane structure and bifurcations) of two-dimensional noninvertible maps, i.e. maps having either a non-unique inverse, or no real inverse, according to the plane point. They constitute models of sets of discrete dynamical systems encountered in Engineering (Control, Signal Processing, Electronics), Physics, Economics, Life Sciences. Compared to the studies made in the one-dimensional case, the two-dimensional situation remained a long time in an underdeveloped state. It is only since these last years that the interest for this resea

  5. Induction of Chirality in Two-Dimensional Nanomaterials: Chiral 2D MoS2 Nanostructures.

    Science.gov (United States)

    Purcell-Milton, Finn; McKenna, Robert; Brennan, Lorcan J; Cullen, Conor P; Guillemeney, Lilian; Tepliakov, Nikita V; Baimuratov, Anvar S; Rukhlenko, Ivan D; Perova, Tatiana S; Duesberg, Georg S; Baranov, Alexander V; Fedorov, Anatoly V; Gun'ko, Yurii K

    2018-02-27

    Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS 2 have gathered much deserved attention recently. Here, we report the induction of chirality into 2D chiral nanomaterials by carrying out liquid exfoliation of MoS 2 in the presence of chiral ligands (cysteine and penicillamine) in water. This processing resulted in exfoliated chiral 2D MoS 2 nanosheets showing strong circular dichroism signals, which were far past the onset of the original chiral ligand signals. Using theoretical modeling, we demonstrated that the chiral nature of MoS 2 nanosheets is related to the presence of chiral ligands causing preferential folding of the MoS 2 sheets. There was an excellent match between the theoretically calculated and experimental spectra. We believe that, due to their high aspect ratio planar morphology, chiral 2D nanomaterials could offer great opportunities for the development of chiroptical sensors, materials, and devices for valleytronics and other potential applications. In addition, chirality plays a key role in many chemical and biological systems, with chiral molecules and materials critical for the further development of biopharmaceuticals and fine chemicals, and this research therefore should have a strong impact on relevant areas of science and technology such as nanobiotechnology, nanomedicine, and nanotoxicology.

  6. Application of a method for comparing one-dimensional and two-dimensional models of a ground-water flow system

    International Nuclear Information System (INIS)

    Naymik, T.G.

    1978-01-01

    To evaluate the inability of a one-dimensional ground-water model to interact continuously with surrounding hydraulic head gradients, simulations using one-dimensional and two-dimensional ground-water flow models were compared. This approach used two types of models: flow-conserving one-and-two dimensional models, and one-dimensional and two-dimensional models designed to yield two-dimensional solutions. The hydraulic conductivities of controlling features were varied and model comparison was based on the travel times of marker particles. The solutions within each of the two model types compare reasonably well, but a three-dimensional solution is required to quantify the comparison

  7. Discrete breathers in a two-dimensional Fermi-Pasta-Ulam lattice

    International Nuclear Information System (INIS)

    Butt, Imran A; Wattis, Jonathan A D

    2006-01-01

    Using asymptotic methods, we investigate whether discrete breathers are supported by a two-dimensional Fermi-Pasta-Ulam lattice. A scalar (one-component) two-dimensional Fermi-Pasta-Ulam lattice is shown to model the charge stored within an electrical transmission lattice. A third-order multiple-scale analysis in the semi-discrete limit fails, since at this order, the lattice equations reduce to the (2 + 1)-dimensional cubic nonlinear Schroedinger (NLS) equation which does not support stable soliton solutions for the breather envelope. We therefore extend the analysis to higher order and find a generalized (2 + 1)-dimensional NLS equation which incorporates higher order dispersive and nonlinear terms as perturbations. We find an ellipticity criterion for the wave numbers of the carrier wave. Numerical simulations suggest that both stationary and moving breathers are supported by the system. Calculations of the energy show the expected threshold behaviour whereby the energy of breathers does not go to zero with the amplitude; we find that the energy threshold is maximized by stationary breathers, and becomes arbitrarily small as the boundary of the domain of ellipticity is approached

  8. Twelve inequivalent Dirac cones in two-dimensional ZrB2

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Bezanilla, Alejandro

    2018-01-01

    Theoretical evidence of the existence of 12 inequivalent Dirac cones at the vicinity of the Fermi energy in monolayered ZrB2 is presented. Two-dimensional ZrB2 is a mechanically stable d- and p-orbital compound exhibiting a unique electronic structure with two Dirac cones out of high-symmetry points in the irreducible Brillouin zone with a small electron-pocket compensation. First-principles calculations demonstrate that while one of the cones is insensitive to lattice expansion, the second cone vanishes for small perturbation of the vertical Zr position. Internal symmetry breaking with external physical stimuli, along with the relativistic effect of spin-orbit coupling, is able to remove selectively the Dirac cones. A rational explanation in terms of d- and p-orbital mixing is provided to elucidate the origin of the infrequent Dirac cones in a flat structure. The versatility of transition-metal d orbitals combined with the honeycomb lattice provided by the B atoms yields particular features in a two-dimensional material.

  9. Folding two dimensional crystals by swift heavy ion irradiation

    International Nuclear Information System (INIS)

    Ochedowski, Oliver; Bukowska, Hanna; Freire Soler, Victor M.; Brökers, Lara; Ban-d'Etat, Brigitte; Lebius, Henning; Schleberger, Marika

    2014-01-01

    Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS 2 and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS 2 does not

  10. Two-dimensional electron gas in monolayer InN quantum wells

    International Nuclear Information System (INIS)

    Pan, W.; Wang, G. T.; Dimakis, E.; Moustakas, T. D.; Tsui, D. C.

    2014-01-01

    We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in a superlattice structure of 40 InN quantum wells consisting of one monolayer of InN embedded between 10 nm GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5 × 10 15  cm −2 (or 1.25 × 10 14  cm −2 per InN quantum well, assuming all the quantum wells are connected by diffused indium contacts) and 420 cm 2 /Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES

  11. Two-dimensional analytic weighting functions for limb scattering

    Science.gov (United States)

    Zawada, D. J.; Bourassa, A. E.; Degenstein, D. A.

    2017-10-01

    Through the inversion of limb scatter measurements it is possible to obtain vertical profiles of trace species in the atmosphere. Many of these inversion methods require what is often referred to as weighting functions, or derivatives of the radiance with respect to concentrations of trace species in the atmosphere. Several radiative transfer models have implemented analytic methods to calculate weighting functions, alleviating the computational burden of traditional numerical perturbation methods. Here we describe the implementation of analytic two-dimensional weighting functions, where derivatives are calculated relative to atmospheric constituents in a two-dimensional grid of altitude and angle along the line of sight direction, in the SASKTRAN-HR radiative transfer model. Two-dimensional weighting functions are required for two-dimensional inversions of limb scatter measurements. Examples are presented where the analytic two-dimensional weighting functions are calculated with an underlying one-dimensional atmosphere. It is shown that the analytic weighting functions are more accurate than ones calculated with a single scatter approximation, and are orders of magnitude faster than a typical perturbation method. Evidence is presented that weighting functions for stratospheric aerosols calculated under a single scatter approximation may not be suitable for use in retrieval algorithms under solar backscatter conditions.

  12. Geometrical aspects of solvable two dimensional models

    International Nuclear Information System (INIS)

    Tanaka, K.

    1989-01-01

    It was noted that there is a connection between the non-linear two-dimensional (2D) models and the scalar curvature r, i.e., when r = -2 the equations of motion of the Liouville and sine-Gordon models were obtained. Further, solutions of various classical nonlinear 2D models can be obtained from the condition that the appropriate curvature two form Ω = 0, which suggests that these models are closely related. This relation is explored further in the classical version by obtaining the equations of motion from the evolution equations, the infinite number of conserved quantities, and the common central charge. The Poisson brackets of the solvable 2D models are specified by the Virasoro algebra. 21 refs

  13. Infrared radiative transfer in dense disks around young stars

    International Nuclear Information System (INIS)

    Dent, W.R.F.

    1988-01-01

    A two-dimensional radiative transfer program has been used to determine the temperature distribution within cylindrically symmetric, centrally heated dust clouds. In particular, the disk-shaped structures observed around young luminous stars have been modeled. Changing the dust distribution in these disks primarily affected the observed morphology in the near-infrared and far-infrared, and at millimeter wavelengths. The overall cloud spectrum, however, was mainly determined by the characteristics of the grains themselves. Comparison with published far-infrared and molecular line data has indicated that the dust density can generally be modeled by a power-law distribution in r with index of -2 and an exponential in z with disk thickness proportional to 1/r. When observed nearly edge-on, scattered direct stellar radiation is observed in the polar regions in the form of comet-shaped lobes of emission. 26 references

  14. Complex dynamical invariants for two-dimensional complex potentials

    Indian Academy of Sciences (India)

    Abstract. Complex dynamical invariants are searched out for two-dimensional complex poten- tials using rationalization method within the framework of an extended complex phase space characterized by x = x1 + ip3, y = x2 + ip4, px = p1 + ix3, py = p2 + ix4. It is found that the cubic oscillator and shifted harmonic oscillator ...

  15. On the size distribution of one-, two- and three-dimensional Voronoi cells

    International Nuclear Information System (INIS)

    Marthinsen, K.

    1994-03-01

    The present report gives a presentation of the different cell size distribution obtained by computer simulations of random Voronoi cell structures in one-, two- and three-dimensional space. The random Voronoi cells are constructed from cell centroids randomly distributed along a string, in the plane and in three-dimensional space, respectively. The size distributions are based on 2-3 · 10 4 cells. For the spacial polyhedra both the distribution of volumes, areas and radii are presented, and the two latter quantities are compared to the distributions of areas and radii from a planar section through the three-dimensional structure as well as to the corresponding distributions obtained from a pure two-dimensional cell structure. 11 refs., 11 figs

  16. Efficient two-dimensional compressive sensing in MIMO radar

    Science.gov (United States)

    Shahbazi, Nafiseh; Abbasfar, Aliazam; Jabbarian-Jahromi, Mohammad

    2017-12-01

    Compressive sensing (CS) has been a way to lower sampling rate leading to data reduction for processing in multiple-input multiple-output (MIMO) radar systems. In this paper, we further reduce the computational complexity of a pulse-Doppler collocated MIMO radar by introducing a two-dimensional (2D) compressive sensing. To do so, we first introduce a new 2D formulation for the compressed received signals and then we propose a new measurement matrix design for our 2D compressive sensing model that is based on minimizing the coherence of sensing matrix using gradient descent algorithm. The simulation results show that our proposed 2D measurement matrix design using gradient decent algorithm (2D-MMDGD) has much lower computational complexity compared to one-dimensional (1D) methods while having better performance in comparison with conventional methods such as Gaussian random measurement matrix.

  17. Ray trace visualization of negative refraction of light in two-dimensional air-bridged silicon photonic crystal slabs at 1.55 microm.

    Science.gov (United States)

    Gan, Lin; Liu, Ya-Zhao; Li, Jiang-Yan; Zhang, Ze-Bo; Zhang, Dao-Zhong; Li, Zhi-Yuan

    2009-06-08

    We demonstrate design, fabrication, and ray trace observation of negative refraction of near-infrared light in a two-dimensional square lattice of air holes etched into an air-bridged silicon slab. Special surface morphologies are designed to reduce the impedance mismatch when light refracts from a homogeneous silicon slab into the photonic crystal slab. We clearly observed negative refraction of infrared light for TE-like modes in a broad wavelength range by using scanning near-field optical microscopy technology. The experimental results are in good agreement with finite-difference time-domain simulations. The results indicate the designed photonic crystal structure can serve as polarization beam splitter.

  18. Depth-enhanced three-dimensional-two-dimensional convertible display based on modified integral imaging.

    Science.gov (United States)

    Park, Jae-Hyeung; Kim, Hak-Rin; Kim, Yunhee; Kim, Joohwan; Hong, Jisoo; Lee, Sin-Doo; Lee, Byoungho

    2004-12-01

    A depth-enhanced three-dimensional-two-dimensional convertible display that uses a polymer-dispersed liquid crystal based on the principle of integral imaging is proposed. In the proposed method, a lens array is located behind a transmission-type display panel to form an array of point-light sources, and a polymer-dispersed liquid crystal is electrically controlled to pass or to scatter light coming from these point-light sources. Therefore, three-dimensional-two-dimensional conversion is accomplished electrically without any mechanical movement. Moreover, the nonimaging structure of the proposed method increases the expressible depth range considerably. We explain the method of operation and present experimental results.

  19. TWO-DIMENSIONAL CORE-COLLAPSE SUPERNOVA MODELS WITH MULTI-DIMENSIONAL TRANSPORT

    International Nuclear Information System (INIS)

    Dolence, Joshua C.; Burrows, Adam; Zhang, Weiqun

    2015-01-01

    We present new two-dimensional (2D) axisymmetric neutrino radiation/hydrodynamic models of core-collapse supernova (CCSN) cores. We use the CASTRO code, which incorporates truly multi-dimensional, multi-group, flux-limited diffusion (MGFLD) neutrino transport, including all relevant O(v/c) terms. Our main motivation for carrying out this study is to compare with recent 2D models produced by other groups who have obtained explosions for some progenitor stars and with recent 2D VULCAN results that did not incorporate O(v/c) terms. We follow the evolution of 12, 15, 20, and 25 solar-mass progenitors to approximately 600 ms after bounce and do not obtain an explosion in any of these models. Though the reason for the qualitative disagreement among the groups engaged in CCSN modeling remains unclear, we speculate that the simplifying ''ray-by-ray'' approach employed by all other groups may be compromising their results. We show that ''ray-by-ray'' calculations greatly exaggerate the angular and temporal variations of the neutrino fluxes, which we argue are better captured by our multi-dimensional MGFLD approach. On the other hand, our 2D models also make approximations, making it difficult to draw definitive conclusions concerning the root of the differences between groups. We discuss some of the diagnostics often employed in the analyses of CCSN simulations and highlight the intimate relationship between the various explosion conditions that have been proposed. Finally, we explore the ingredients that may be missing in current calculations that may be important in reproducing the properties of the average CCSNe, should the delayed neutrino-heating mechanism be the correct mechanism of explosion

  20. Evidence for the quasi-two dimensional behavior of the vortex structure in Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Pastoriza, H.; Arribere, A.; Goffman, M.F.; Cruz, F. de la; Mitzi, D.B.; Kapitulnik, A.

    1994-01-01

    AC susceptibility and dc magnetization measurements on Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) single crystals in a wide range of temperatures clearly show that below the dc irreversibility line the vortex system loss the long range order in the c direction. The susceptibility data taken at 7 Hz show the different nature of two dissipation peaks: One related to the interplane currents at temperatures well below the dc irreversibility line and the other associated with the intraplane ones at temperatures above that line. In this sense the irreversibility line corresponds to the temperature where quasi-two dimensional vortices are depinned. (orig.)

  1. Logarithmic Superdiffusion in Two Dimensional Driven Lattice Gases

    Science.gov (United States)

    Krug, J.; Neiss, R. A.; Schadschneider, A.; Schmidt, J.

    2018-03-01

    The spreading of density fluctuations in two-dimensional driven diffusive systems is marginally anomalous. Mode coupling theory predicts that the diffusivity in the direction of the drive diverges with time as (ln t)^{2/3} with a prefactor depending on the macroscopic current-density relation and the diffusion tensor of the fluctuating hydrodynamic field equation. Here we present the first numerical verification of this behavior for a particular version of the two-dimensional asymmetric exclusion process. Particles jump strictly asymmetrically along one of the lattice directions and symmetrically along the other, and an anisotropy parameter p governs the ratio between the two rates. Using a novel massively parallel coupling algorithm that strongly reduces the fluctuations in the numerical estimate of the two-point correlation function, we are able to accurately determine the exponent of the logarithmic correction. In addition, the variation of the prefactor with p provides a stringent test of mode coupling theory.

  2. Efficient construction of two-dimensional cluster states with probabilistic quantum gates

    International Nuclear Information System (INIS)

    Chen Qing; Cheng Jianhua; Wang Kelin; Du Jiangfeng

    2006-01-01

    We propose an efficient scheme for constructing arbitrary two-dimensional (2D) cluster states using probabilistic entangling quantum gates. In our scheme, the 2D cluster state is constructed with starlike basic units generated from 1D cluster chains. By applying parallel operations, the process of generating 2D (or higher-dimensional) cluster states is significantly accelerated, which provides an efficient way to implement realistic one-way quantum computers

  3. Low-cost three-dimensional gait analysis system for mice with an infrared depth sensor.

    Science.gov (United States)

    Nakamura, Akihiro; Funaya, Hiroyuki; Uezono, Naohiro; Nakashima, Kinichi; Ishida, Yasumasa; Suzuki, Tomohiro; Wakana, Shigeharu; Shibata, Tomohiro

    2015-11-01

    Three-dimensional (3D) open-field gait analysis of mice is an essential procedure in genetic and nerve regeneration research. Existing gait analysis systems are generally expensive and may interfere with the natural behaviors of mice because of optical markers and transparent floors. In contrast, the proposed system captures the subjects shape from beneath using a low-cost infrared depth sensor (Microsoft Kinect) and an opaque infrared pass filter. This means that we can track footprints and 3D paw-tip positions without optical markers or a transparent floor, thereby preventing any behavioral changes. Our experimental results suggest with healthy mice that they are more active on opaque floors and spend more time in the center of the open-field, when compared with transparent floors. The proposed system detected footprints with a comparable performance to existing systems, and precisely tracked the 3D paw-tip positions in the depth image coordinates. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  4. Functional inks and printing of two-dimensional materials.

    Science.gov (United States)

    Hu, Guohua; Kang, Joohoon; Ng, Leonard W T; Zhu, Xiaoxi; Howe, Richard C T; Jones, Christopher G; Hersam, Mark C; Hasan, Tawfique

    2018-05-08

    Graphene and related two-dimensional materials provide an ideal platform for next generation disruptive technologies and applications. Exploiting these solution-processed two-dimensional materials in printing can accelerate this development by allowing additive patterning on both rigid and conformable substrates for flexible device design and large-scale, high-speed, cost-effective manufacturing. In this review, we summarise the current progress on ink formulation of two-dimensional materials and the printable applications enabled by them. We also present our perspectives on their research and technological future prospects.

  5. High breakdown voltage quasi-two-dimensional β-Ga2O3 field-effect transistors with a boron nitride field plate

    Science.gov (United States)

    Bae, Jinho; Kim, Hyoung Woo; Kang, In Ho; Yang, Gwangseok; Kim, Jihyun

    2018-03-01

    We have demonstrated a β-Ga2O3 metal-semiconductor field-effect transistor (MESFET) with a high off-state breakdown voltage (344 V), based on a quasi-two-dimensional β-Ga2O3 field-plated with hexagonal boron nitride (h-BN). Both the β-Ga2O3 and h-BN were mechanically exfoliated from their respective crystal substrates, followed by dry-transfer onto a SiO2/Si substrate for integration into a high breakdown voltage quasi-two-dimensional β-Ga2O3 MESFETs. N-type conducting behavior was observed in the fabricated β-Ga2O3 MESFETs, along with a high on/off current ratio (>106) and excellent current saturation. A three-terminal off-state breakdown voltage of 344 V was obtained, with a threshold voltage of -7.3 V and a subthreshold swing of 84.6 mV/dec. The distribution of electric fields in the quasi-two-dimensional β-Ga2O3 MESFETs was simulated to analyze the role of the dielectric h-BN field plate in improving the off-state breakdown voltage. The stability of the field-plated β-Ga2O3 MESFET in air was confirmed after storing the MESFET in ambient air for one month. Our results pave the way for unlocking the full potential of β-Ga2O3 for use in a high-power nano-device with an ultrahigh breakdown voltage.

  6. Full dimensional (15-dimensional) quantum-dynamical simulation of the protonated water-dimer III: Mixed Jacobi-valence parametrization and benchmark results for the zero point energy, vibrationally excited states, and infrared spectrum.

    Science.gov (United States)

    Vendrell, Oriol; Brill, Michael; Gatti, Fabien; Lauvergnat, David; Meyer, Hans-Dieter

    2009-06-21

    Quantum dynamical calculations are reported for the zero point energy, several low-lying vibrational states, and the infrared spectrum of the H(5)O(2)(+) cation. The calculations are performed by the multiconfiguration time-dependent Hartree (MCTDH) method. A new vector parametrization based on a mixed Jacobi-valence description of the system is presented. With this parametrization the potential energy surface coupling is reduced with respect to a full Jacobi description, providing a better convergence of the n-mode representation of the potential. However, new coupling terms appear in the kinetic energy operator. These terms are derived and discussed. A mode-combination scheme based on six combined coordinates is used, and the representation of the 15-dimensional potential in terms of a six-combined mode cluster expansion including up to some 7-dimensional grids is discussed. A statistical analysis of the accuracy of the n-mode representation of the potential at all orders is performed. Benchmark, fully converged results are reported for the zero point energy, which lie within the statistical uncertainty of the reference diffusion Monte Carlo result for this system. Some low-lying vibrationally excited eigenstates are computed by block improved relaxation, illustrating the applicability of the approach to large systems. Benchmark calculations of the linear infrared spectrum are provided, and convergence with increasing size of the time-dependent basis and as a function of the order of the n-mode representation is studied. The calculations presented here make use of recent developments in the parallel version of the MCTDH code, which are briefly discussed. We also show that the infrared spectrum can be computed, to a very good approximation, within D(2d) symmetry, instead of the G(16) symmetry used before, in which the complete rotation of one water molecule with respect to the other is allowed, thus simplifying the dynamical problem.

  7. K-FIX: a computer program for transient, two-dimensional, two-fluid flow. THREED: an extension of the K-FIX code for three-dimensional calculations

    International Nuclear Information System (INIS)

    Rivard, W.C.; Torrey, M.D.

    1978-10-01

    The transient, two-dimensional, two-fluid code K-FIX has been extended to perform three-dimensional calculations. This capability is achieved by adding five modification sets of FORTRAN statements to the basic two-dimensional code. The modifications are listed and described, and a complete listing of the three-dimensional code is provided. Results of an example problem are provided for verification

  8. Experimental realization of optical lumped nanocircuits at infrared wavelengths.

    Science.gov (United States)

    Sun, Yong; Edwards, Brian; Alù, Andrea; Engheta, Nader

    2012-01-29

    The integration of radiofrequency electronic methodologies on micro- as well as nanoscale platforms is crucial for information processing and data-storage technologies. In electronics, radiofrequency signals are controlled and manipulated by 'lumped' circuit elements, such as resistors, inductors and capacitors. In earlier work, we theoretically proposed that optical nanostructures, when properly designed and judiciously arranged, could behave as nanoscale lumped circuit elements--but at optical frequencies. Here, for the first time we experimentally demonstrate a two-dimensional optical nanocircuit at mid-infrared wavelengths. With the guidance of circuit theory, we design and fabricate arrays of Si3N4 nanorods with specific deep subwavelength cross-sections, quantitatively evaluate their equivalent impedance as lumped circuit elements in the mid-infrared regime, and by Fourier transform infrared spectroscopy show that these nanostructures can indeed function as two-dimensional optical lumped circuit elements. We further show that the connections among nanocircuit elements, in particular whether they are in series or in parallel combination, can be controlled by the polarization of impinging optical signals, realizing the notion of 'stereo-circuitry' in metatronics-metamaterials-inspired optical circuitry.

  9. Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

    Energy Technology Data Exchange (ETDEWEB)

    Kamaraju, N., E-mail: nkamaraju@lanl.gov; Taylor, A. J.; Prasankumar, R. P., E-mail: rpprasan@lanl.gov [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Pan, W.; Reno, J. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Ekenberg, U. [Semiconsultants, Brunnsgrnd 12, SE-18773 Täby (Sweden); Gvozdić, D. M. [School of Electrical Engineering, University of Belgrade, Belgrade 11120 (Serbia); Boubanga-Tombet, S. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-Ku, Sendai (Japan); Upadhya, P. C. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Laboratory for Electro-Optics Systems, Indian Space Research Organization, Bangalore 560058 (India)

    2015-01-19

    Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG, in contrast with the dominance of superradiant damping in two-dimensional electron gases. Our results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.

  10. Study on electrical defects level in single layer two-dimensional Ta2O5

    Science.gov (United States)

    Dahai, Li; Xiongfei, Song; Linfeng, Hu; Ziyi, Wang; Rongjun, Zhang; Liangyao, Chen; David, Wei Zhang; Peng, Zhou

    2016-04-01

    Two-dimensional atomic-layered material is a recent research focus, and single layer Ta2O5 used as gate dielectric in field-effect transistors is obtained via assemblies of Ta2O5 nanosheets. However, the electrical performance is seriously affected by electronic defects existing in Ta2O5. Therefore, spectroscopic ellipsometry is used to calculate the transition energies and corresponding probabilities for two different charged oxygen vacancies, whose existence is revealed by x-ray photoelectron spectroscopy analysis. Spectroscopic ellipsometry fitting also calculates the thickness of single layer Ta2O5, exhibiting good agreement with atomic force microscopy measurement. Nondestructive and noncontact spectroscopic ellipsometry is appropriate for detecting the electrical defects level of single layer Ta2O5. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174058 and 61376093), the Fund from Shanghai Municipal Science and Technology Commission (Grant No. 13QA1400400), the National Science and Technology Major Project, China (Grant No. 2011ZX02707), and the Innovation Program of Shanghai Municipal Education Commission (Grant No. 12ZZ010).

  11. Overview of Dynamics Integration Research (DIR) program at Langley Research Center

    Science.gov (United States)

    Sliwa, Steven M.; Abel, Irving

    1989-01-01

    Research goals and objectives for an ongoing activity at Langley Research Center (LaRC) are described. The activity is aimed principally at dynamics optimization for aircraft. The effort involves active participation by the Flight Systems, Structures, and Electronics directorates at LaRC. The Functional Integration Technology (FIT) team has been pursuing related goals since 1985. A prime goal has been the integration and optimization of vehicle dynamics through collaboration at the basic principles or equation level. Some significant technical progress has been accomplished since then and is reflected here. An augmentation for this activity, Dynamics Integration Research (DIR), has been proposed to NASA Headquarters and is being considered for funding in FY 1990 or FY 1991.

  12. Two-dimensional critical phenomena

    International Nuclear Information System (INIS)

    Saleur, H.

    1987-09-01

    Two dimensional critical systems are studied using transformation to free fields and conformal invariance methods. The relations between the two approaches are also studied. The analytical results obtained generally depend on universality hypotheses or on renormalization group trajectories which are not established rigorously, so numerical verifications, mainly using the transfer matrix approach, are presented. The exact determination of critical exponents; the partition functions of critical models on toruses; and results as the critical point is approached are discussed [fr

  13. Two-dimensional electronic spectroscopy with birefringent wedges

    Energy Technology Data Exchange (ETDEWEB)

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2014-12-15

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  14. Folding two dimensional crystals by swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ochedowski, Oliver; Bukowska, Hanna [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Freire Soler, Victor M. [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Departament de Fisica Aplicada i Optica, Universitat de Barcelona, E08028 Barcelona (Spain); Brökers, Lara [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Ban-d' Etat, Brigitte; Lebius, Henning [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France); Schleberger, Marika, E-mail: marika.schleberger@uni-due.de [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany)

    2014-12-01

    Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS{sub 2} and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS{sub 2} does not.

  15. Explorative data analysis of two-dimensional electrophoresis gels

    DEFF Research Database (Denmark)

    Schultz, J.; Gottlieb, D.M.; Petersen, Marianne Kjerstine

    2004-01-01

    of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine......Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening...... if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots...

  16. Femtosecond X-ray diffraction from two-dimensional protein crystals

    Directory of Open Access Journals (Sweden)

    Matthias Frank

    2014-03-01

    Full Text Available X-ray diffraction patterns from two-dimensional (2-D protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.

  17. Airy beams on two dimensional materials

    Science.gov (United States)

    Imran, Muhammad; Li, Rujiang; Jiang, Yuyu; Lin, Xiao; Zheng, Bin; Dehdashti, Shahram; Xu, Zhiwei; Wang, Huaping

    2018-05-01

    We propose that quasi-transverse-magnetic (quasi-TM) Airy beams can be supported on two dimensional (2D) materials. By taking graphene as a typical example, the solution of quasi-TM Airy beams is studied under the paraxial approximation. The analytical field intensity in a bilayer graphene-based planar plasmonic waveguide is confirmed by the simulation results. Due to the tunability of the chemical potential of graphene, the self-accelerating behavior of the quasi-TM Airy beam can be steered effectively. 2D materials thus provide a good platform to investigate the propagation of Airy beams.

  18. Single-shot ultrabroadband two-dimensional electronic spectroscopy of the light-harvesting complex LH2.

    Science.gov (United States)

    Harel, Elad; Long, Phillip D; Engel, Gregory S

    2011-05-01

    Here we present two-dimensional (2D) electronic spectra of the light-harvesting complex LH2 from purple bacteria using coherent pulses with bandwidth of over 100 nm FWHM. This broadband excitation and detection has allowed the simultaneous capture of both the B800 and B850 bands using a single light source. We demonstrate that one laser pulse is sufficient to capture the entire 2D electronic spectrum with a high signal-to-noise ratio. At a waiting time of 800 fs, we observe population transfer from the B800 to B850 band as manifested by a prominent cross peak. These results will enable observation of the dynamics of biological systems across both ultrafast (1 ms) timescales simultaneously.

  19. Resolving molecular vibronic structure using high-sensitivity two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bizimana, Laurie A.; Brazard, Johanna; Carbery, William P.; Gellen, Tobias; Turner, Daniel B., E-mail: dturner@nyu.edu [Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003 (United States)

    2015-10-28

    Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.

  20. Two-dimensional characterization of atmospheric profile retrievals from limb sounding observations

    International Nuclear Information System (INIS)

    Worden, J.R.; Bowman, K.W.; Jones, D.B.

    2004-01-01

    Limb sounders measure atmospheric radiation that is dependent on atmospheric temperature and constituents that have a radial and angular distribution in Earth-centered coordinates. In order to evaluate the sensitivity of a limb retrieval to radial and angular distributions of trace gas concentrations, we perform and characterize one-dimensional (vertical) and two-dimensional (radial and angular) atmospheric profile retrievals. Our simulated atmosphere for these retrievals is a distribution of carbon monoxide (CO), which represents a plume off the coast of south-east Asia. Both the one-dimensional (1D) and two-dimensional (2D) limb retrievals are characterized by evaluating their averaging kernels and error covariances on a radial and angular grid that spans the plume. We apply this 2D characterization of a limb retrieval to a comparison of the 2D retrieval with the 1D (vertical) retrieval. By characterizing a limb retrieval in two dimensions the location of the air mass where the retrievals are most sensitive can be determined. For this test case the retrievals are most sensitive to the CO concentrations about 2 deg.latitude in front of the tangent point locations. We find the information content for the 2D retrieval is an order of magnitude larger and the degrees of freedom is about a factor of two larger than that of the 1D retrieval primarily because the 2D retrieval can estimate angular distributions of CO concentrations. This 2D characterization allows the radial and angular resolution as well as the degrees of freedom and information content to be computed for these limb retrievals. We also use the 2D averaging kernel to develop a strategy for validation of a limb retrieval with an in situ measurement

  1. Two-dimensional capillary origami

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu

    2016-01-08

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.

  2. Two-dimensional capillary origami

    International Nuclear Information System (INIS)

    Brubaker, N.D.; Lega, J.

    2016-01-01

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.

  3. Electronic band structure of Two-Dimensional WS2/Graphene van der Waals Heterostructures

    Science.gov (United States)

    Henck, Hugo; Ben Aziza, Zeineb; Pierucci, Debora; Laourine, Feriel; Reale, Francesco; Palczynski, Pawel; Chaste, Julien; Silly, Mathieu G.; Bertran, François; Le Fèvre, Patrick; Lhuillier, Emmanuel; Wakamura, Taro; Mattevi, Cecilia; Rault, Julien E.; Calandra, Matteo; Ouerghi, Abdelkarim

    2018-04-01

    Combining single-layer two-dimensional semiconducting transition-metal dichalcogenides (TMDs) with a graphene layer in van der Waals heterostructures offers an intriguing means of controlling the electronic properties through these heterostructures. Here, we report the electronic and structural properties of transferred single-layer W S2 on epitaxial graphene using micro-Raman spectroscopy, angle-resolved photoemission spectroscopy measurements, and density functional theory (DFT) calculations. The results show good electronic properties as well as a well-defined band arising from the strong splitting of the single-layer W S2 valence band at the K points, with a maximum splitting of 0.44 eV. By comparing our DFT results with local and hybrid functionals, we find the top valence band of the experimental heterostructure is close to the calculations for suspended single-layer W S2 . Our results provide an important reference for future studies of electronic properties of W S2 and its applications in valleytronic devices.

  4. Two-dimensional black holes and non-commutative spaces

    International Nuclear Information System (INIS)

    Sadeghi, J.

    2008-01-01

    We study the effects of non-commutative spaces on two-dimensional black hole. The event horizon of two-dimensional black hole is obtained in non-commutative space up to second order of perturbative calculations. A lower limit for the non-commutativity parameter is also obtained. The observer in that limit in contrast to commutative case see two horizon

  5. Graphene/MoS2 hybrid technology for large-scale two-dimensional electronics.

    Science.gov (United States)

    Yu, Lili; Lee, Yi-Hsien; Ling, Xi; Santos, Elton J G; Shin, Yong Cheol; Lin, Yuxuan; Dubey, Madan; Kaxiras, Efthimios; Kong, Jing; Wang, Han; Palacios, Tomás

    2014-06-11

    Two-dimensional (2D) materials have generated great interest in the past few years as a new toolbox for electronics. This family of materials includes, among others, metallic graphene, semiconducting transition metal dichalcogenides (such as MoS2), and insulating boron nitride. These materials and their heterostructures offer excellent mechanical flexibility, optical transparency, and favorable transport properties for realizing electronic, sensing, and optical systems on arbitrary surfaces. In this paper, we demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition. We have fabricated high-performance devices and circuits based on this heterostructure, where MoS2 is used as the transistor channel and graphene as contact electrodes and circuit interconnects. We provide a systematic comparison of the graphene/MoS2 heterojunction contact to more traditional MoS2-metal junctions, as well as a theoretical investigation, using density functional theory, of the origin of the Schottky barrier height. The tunability of the graphene work function with electrostatic doping significantly improves the ohmic contact to MoS2. These high-performance large-scale devices and circuits based on this 2D heterostructure pave the way for practical flexible transparent electronics.

  6. Plasma kinetics of Ar/O{sub 2} magnetron discharge by two-dimensional multifluid modeling

    Energy Technology Data Exchange (ETDEWEB)

    Costin, C.; Minea, T. M.; Popa, G.; Gousset, G. [LPGP, UMR 8578, CNRS-Paris-Sud XI University, Bat. 210, Orsay Cedex 91405, France and Faculty of Physics, Al. I. Cuza University, 11 Carol I Blvd., Iasi 700506 (Romania); LPGP, UMR 8578, CNRS-Paris-Sud XI University, Bat. 210, Orsay Cedex 91405 (France); Faculty of Physics, Al. I. Cuza University, 11 Carol I Blvd., Iasi 700506 (Romania); LPGP, UMR 8578, CNRS-Paris-Sud XI University, Bat. 210, Orsay Cedex 91405 (France)

    2010-03-15

    Multifluid two-dimensional model was developed to describe the plasma kinetics of the direct current Ar/O{sub 2} magnetron, coupling two modules: charged particles and neutrals. The first module deals with three positive ions - Ar{sup +}, O{sub 2}{sup +}, and O{sup +} - and two negative species - e{sup -} and O{sup -} - treated by the moments of Boltzmann's equation. The second one follows seven neutral species (Ar, O{sub 2}, O, O{sub 3}, and related metastables) by the multicomponent diffusion technique. The two modules are self-consistently coupled by the mass conservation and kinetic coefficients taking into account more than 100 volume reactions. The steady state is obtained when the overall convergence is achieved. Calculations for 10%O{sub 2} in Ar/O{sub 2} mixture at 2.67 and 4 Pa show that the oxygen excited species are mainly created by electron collisions in the negative glow of the discharge. Decreasing the pressure down to 0.67 Pa, the model reveals the nonlocal behavior of the reactive species. The density gradient of O{sub 2} ground state is reversed with respect to all gradients of the other reactive species, since the latter ones originate from the molecular ground state of oxygen. It is also found that the wall reactions drastically modify the space gradient of neutral reactive species, at least as much as the pressure, even if the discharge operates in compound mode.

  7. Study on general design of dual-DMD based infrared two-band scene simulation system

    Science.gov (United States)

    Pan, Yue; Qiao, Yang; Xu, Xi-ping

    2017-02-01

    Mid-wave infrared(MWIR) and long-wave infrared(LWIR) two-band scene simulation system is a kind of testing equipment that used for infrared two-band imaging seeker. Not only it would be qualified for working waveband, but also realize the essence requests that infrared radiation characteristics should correspond to the real scene. Past single-digital micromirror device (DMD) based infrared scene simulation system does not take the huge difference between targets and background radiation into account, and it cannot realize the separated modulation to two-band light beam. Consequently, single-DMD based infrared scene simulation system cannot accurately express the thermal scene model that upper-computer built, and it is not that practical. To solve the problem, we design a dual-DMD based, dual-channel, co-aperture, compact-structure infrared two-band scene simulation system. The operating principle of the system is introduced in detail, and energy transfer process of the hardware-in-the-loop simulation experiment is analyzed as well. Also, it builds the equation about the signal-to-noise ratio of infrared detector in the seeker, directing the system overall design. The general design scheme of system is given, including the creation of infrared scene model, overall control, optical-mechanical structure design and image registration. By analyzing and comparing the past designs, we discuss the arrangement of optical engine framework in the system. According to the main content of working principle and overall design, we summarize each key techniques in the system.

  8. Two-dimensional Navier-Stokes turbulence in bounded domains

    NARCIS (Netherlands)

    Clercx, H.J.H.; van Heijst, G.J.F.

    In this review we will discuss recent experimental and numerical results of quasi-two-dimensional decaying and forced Navier–Stokes turbulence in bounded domains. We will give a concise overview of developments in two-dimensional turbulence research, with emphasis on the progress made during the

  9. Two-dimensional Navier-Stokes turbulence in bounded domains

    NARCIS (Netherlands)

    Clercx, H.J.H.; Heijst, van G.J.F.

    2009-01-01

    In this review we will discuss recent experimental and numerical results of quasi-two-dimensional decaying and forced Navier–Stokes turbulence in bounded domains. We will give a concise overview of developments in two-dimensional turbulence research, with emphasis on the progress made during the

  10. Near-infrared light activation of quenched liposomal Ce6 for synergistic cancer phototherapy with effective skin protection.

    Science.gov (United States)

    Feng, Liangzhu; Tao, Danlei; Dong, Ziliang; Chen, Qian; Chao, Yu; Liu, Zhuang; Chen, Meiwan

    2017-05-01

    Current photodynamic therapy (PDT) is suffering from limited efficacy towards hypoxia tumors and severe post-treatment photo-toxicity such as light-induced skin damages. To make PDT more effective in cancer treatment while being patient-comfortable, herein, a hexylamine conjugated chlorin e6 (hCe6) as the photosensitizer together with a lipophilic near-infrared (NIR) dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) are co-encapsulated into polyethylene glycol (PEG) shelled liposomes. In the obtained DiR-hCe6-liposome, the photosensitizing effect of hCe6 is quenched by DiR via fluorescence resonance energy transfer (FRET). Interestingly, upon irradiation with a 785-nm NIR laser to photobleach DiR, both fluorescence and photodynamic effect of hCe6 in DiR-hCe6-liposome would be activated. Meanwhile, such NIR irradiation applied on tumors of mice with intravenous injection of DiR-hCe6-liposome could result in mild photothermal heating, which in turn would promote intra-tumor blood flow and relieve tumor hypoxia, contributing to the enhanced photodynamic tumor treatment. Importantly, compared to hCe6-loaded liposomes, DiR-hCe6-liposome without being activated by the 785-nm laser shows much lower skin photo-toxicity, demonstrating its great skin protection effect. This work demonstrates a promising yet simple strategy to prepare NIR-light-activatable photodynamic theranostics for synergistic cancer phototherapy, which is featured high specificity/efficacy in tumor treatment with minimal photo-toxicity towards the skin. Copyright © 2016. Published by Elsevier Ltd.

  11. Solitary wave solutions of two-dimensional nonlinear Kadomtsev ...

    Indian Academy of Sciences (India)

    Aly R Seadawy

    2017-09-13

    Sep 13, 2017 ... We considered the two-dimensional DASWs in colli- sionless, unmagnetized cold plasma consisting of dust fluid, ions and electrons. The dynamics of DASWs is governed by the normalized fluid equations of nonlin- ear continuity (1), nonlinear motion of system (2) and. (3) and linear Poisson equation (4) as.

  12. Topotactic transformations of superstructures: from thin films to two-dimensional networks to nested two-dimensional networks.

    Science.gov (United States)

    Guo, Chuan Fei; Cao, Sihai; Zhang, Jianming; Tang, Haoying; Guo, Shengming; Tian, Ye; Liu, Qian

    2011-06-01

    Design and synthesis of super-nanostructures is one of the key and prominent topics in nanotechnology. Here we propose a novel methodology for synthesizing complex hierarchical superstructures using sacrificial templates composed of ordered two-dimensional (2D) nanostructures through lattice-directed topotactic transformations. The fabricated superstructures are nested 2D orthogonal Bi(2)S(3) networks composed of nanorods. Further investigation indicates that the lattice matching between the product and sacrificial template is the dominant mechanism for the formation of the superstructures, which agrees well with the simulation results based on an anisotropic nucleation and growth analysis. Our approach may provide a promising way toward a lattice-directed nonlithographic nanofabrication technique for making functional porous nanoarchitectures and electronic devices. © 2011 American Chemical Society

  13. Two dimensional analytical model for a reconfigurable field effect transistor

    Science.gov (United States)

    Ranjith, R.; Jayachandran, Remya; Suja, K. J.; Komaragiri, Rama S.

    2018-02-01

    This paper presents two-dimensional potential and current models for a reconfigurable field effect transistor (RFET). Two potential models which describe subthreshold and above-threshold channel potentials are developed by solving two-dimensional (2D) Poisson's equation. In the first potential model, 2D Poisson's equation is solved by considering constant/zero charge density in the channel region of the device to get the subthreshold potential characteristics. In the second model, accumulation charge density is considered to get above-threshold potential characteristics of the device. The proposed models are applicable for the device having lightly doped or intrinsic channel. While obtaining the mathematical model, whole body area is divided into two regions: gated region and un-gated region. The analytical models are compared with technology computer-aided design (TCAD) simulation results and are in complete agreement for different lengths of the gated regions as well as at various supply voltage levels.

  14. Development of Two-Dimensional NMR

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 11. Development of Two-Dimensional NMR: Strucure Determination of Biomolecules in Solution. Anil Kumar. General Article Volume 20 Issue 11 November 2015 pp 995-1002 ...

  15. SU-F-J-88: Comparison of Two Deformable Image Registration Algorithms for CT-To-CT Contour Propagation

    International Nuclear Information System (INIS)

    Gopal, A; Xu, H; Chen, S

    2016-01-01

    Purpose: To compare the contour propagation accuracy of two deformable image registration (DIR) algorithms in the Raystation treatment planning system – the “Hybrid” algorithm based on image intensities and anatomical information; and the “Biomechanical” algorithm based on linear anatomical elasticity and finite element modeling. Methods: Both DIR algorithms were used for CT-to-CT deformation for 20 lung radiation therapy patients that underwent treatment plan revisions. Deformation accuracy was evaluated using landmark tracking to measure the target registration error (TRE) and inverse consistency error (ICE). The deformed contours were also evaluated against physician drawn contours using Dice similarity coefficients (DSC). Contour propagation was qualitatively assessed using a visual quality score assigned by physicians, and a refinement quality score (0 0.9 for lungs, > 0.85 for heart, > 0.8 for liver) and similar qualitative assessments (VQS 0.75 for lungs). When anatomical structures were used to control the deformation, the DSC improved more significantly for the biomechanical DIR compared to the hybrid DIR, while the VQS and RQS improved only for the controlling structures. However, while the inclusion of controlling structures improved the TRE for the hybrid DIR, it increased the TRE for the biomechanical DIR. Conclusion: The hybrid DIR was found to perform slightly better than the biomechanical DIR based on lower TRE while the DSC, VQS, and RQS studies yielded comparable results for both. The use of controlling structures showed considerable improvement in the hybrid DIR results and is recommended for clinical use in contour propagation.

  16. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    OpenAIRE

    Nikola Stefanović

    2007-01-01

    In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic ...

  17. Magnetic structure of the quasi-two-dimensional compound CoTa{sub 2}O{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Kinast, E.J. [Universidade Estadual do Rio Grande do Sul, Rua 7 de Setembro, 1156, 90010-191 Porto Alegre (Brazil); Santos, C.A. dos [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil); Schmitt, D. [Laboratoire de Geophysique Interne et Tectonophysique, Universite Joseph Fourier, B. P. 53, 38041 Grenoble Cedex 9 (France); Isnard, O., E-mail: olivier.isnard@grenoble.cnrs.f [Institut Neel, CNRS/Universite Jospeh Fourier, avenue des martyrs B. P. 166, 38042 Grenoble Cedex 9 (France); Gusmao, M.A.; Cunha, J.B.M. da [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, C.P. 15051, 91501-970 Porto Alegre (Brazil)

    2010-02-18

    We report on a detailed investigation of magnetic properties of CoTa{sub 2}O{sub 6} using several techniques: neutron and X-ray diffraction, specific-heat, magnetic susceptibility, and magnetization measurements. The compound shows quasi-two-dimensional behavior due to its layered structure of alternating Co-O and Ta-O planes. We find that all magnetic moments lie entirely in the Co-O planes, along easy axes determined by the orientations of oxygen octahedra that surround the Co ions. The easy axes in successive magnetic planes have relative orientations that differ by 90{sup o}. Antiferromagnetic ordering is observed below 6.6 K, with propagation vectors ({+-}1/4,1/4,1/4) associated to the two non-equivalent sets of Co{sup 2+} ions, whose magnetic moments are perpendicularly oriented.

  18. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.

    2015-12-09

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  19. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.; Lan, Yann Wen; Zeng, Caifu; Chen, Jyun Hong; Kou, Xufeng; Navabi, Aryan; Tang, Jianshi; Montazeri, Mohammad; Adleman, James R.; Lerner, Mitchell B.; Zhong, Yuan Liang; Li, Lain-Jong; Chen, Chii Dong; Wang, Kang L.

    2015-01-01

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  20. One-dimensional versus two-dimensional electronic states in vicinal surfaces

    International Nuclear Information System (INIS)

    Ortega, J E; Ruiz-Oses, M; Cordon, J; Mugarza, A; Kuntze, J; Schiller, F

    2005-01-01

    Vicinal surfaces with periodic arrays of steps are among the simplest lateral nanostructures. In particular, noble metal surfaces vicinal to the (1 1 1) plane are excellent test systems to explore the basic electronic properties in one-dimensional superlattices by means of angular photoemission. These surfaces are characterized by strong emissions from free-electron-like surface states that scatter at step edges. Thereby, the two-dimensional surface state displays superlattice band folding and, depending on the step lattice constant d, it splits into one-dimensional quantum well levels. Here we use high-resolution, angle-resolved photoemission to analyse surface states in a variety of samples, in trying to illustrate the changes in surface state bands as a function of d

  1. Densis. Densimetric representation of two-dimensional matrices

    International Nuclear Information System (INIS)

    Los Arcos Merino, J.M.

    1978-01-01

    Densis is a Fortran V program which allows off-line control of a Calcomp digital plotter, to represent a two-dimensional matrix of numerical elements in the form of a variable shading intensity map in two colours. Each matrix element is associated to a square of a grid which is traced over by lines whose number is a function of the element value according to a selected scale. Program features, subroutine structure and running instructions, are described. Some typical results, for gamma-gamma coincidence experimental data and a sampled two-dimensional function, are indicated. (author)

  2. Two-dimensional PCA-based human gait identification

    Science.gov (United States)

    Chen, Jinyan; Wu, Rongteng

    2012-11-01

    It is very necessary to recognize person through visual surveillance automatically for public security reason. Human gait based identification focus on recognizing human by his walking video automatically using computer vision and image processing approaches. As a potential biometric measure, human gait identification has attracted more and more researchers. Current human gait identification methods can be divided into two categories: model-based methods and motion-based methods. In this paper a two-Dimensional Principal Component Analysis and temporal-space analysis based human gait identification method is proposed. Using background estimation and image subtraction we can get a binary images sequence from the surveillance video. By comparing the difference of two adjacent images in the gait images sequence, we can get a difference binary images sequence. Every binary difference image indicates the body moving mode during a person walking. We use the following steps to extract the temporal-space features from the difference binary images sequence: Projecting one difference image to Y axis or X axis we can get two vectors. Project every difference image in the difference binary images sequence to Y axis or X axis difference binary images sequence we can get two matrixes. These two matrixes indicate the styles of one walking. Then Two-Dimensional Principal Component Analysis(2DPCA) is used to transform these two matrixes to two vectors while at the same time keep the maximum separability. Finally the similarity of two human gait images is calculated by the Euclidean distance of the two vectors. The performance of our methods is illustrated using the CASIA Gait Database.

  3. Novel Au- and Ge-based two-dimensional materials formed through topotactic transitions of AlB2-like structures

    Science.gov (United States)

    Tsetseris, Leonidas

    2016-07-01

    The topotactic reaction of a layered compound, for example CaGe2, with HCl solution is a common and facile method to produce two-dimensional (2D) materials. In this work we demonstrate with first-principles calculations that this technique can potentially lead to a whole new family of 2D materials starting from three-dimensional crystals with AlB2-like structures. As representative cases, we show here that the de-intercalation of Sc and Ca atoms from ScAuGe and Ca2AuGe3 crystals is strongly exothermic and produces the stable 2D monolayers AuGeH and AuGe3H3, respectively. Remarkably, both metals (AuGeH) and semiconductors (AuGe3H3) can be prepared by this method. Based on the broad availability of AlB2-like structures with varying stoichiometries, there are several possibilities to prepare novel functional 2D materials with suitable topotactic transitions.

  4. (2+1-dimensional regular black holes with nonlinear electrodynamics sources

    Directory of Open Access Journals (Sweden)

    Yun He

    2017-11-01

    Full Text Available On the basis of two requirements: the avoidance of the curvature singularity and the Maxwell theory as the weak field limit of the nonlinear electrodynamics, we find two restricted conditions on the metric function of (2+1-dimensional regular black hole in general relativity coupled with nonlinear electrodynamics sources. By the use of the two conditions, we obtain a general approach to construct (2+1-dimensional regular black holes. In this manner, we construct four (2+1-dimensional regular black holes as examples. We also study the thermodynamic properties of the regular black holes and verify the first law of black hole thermodynamics.

  5. Nanostructured Porous Silicon Photonic Crystal for Applications in the Infrared

    Directory of Open Access Journals (Sweden)

    G. Recio-Sánchez

    2012-01-01

    Full Text Available In the last decades great interest has been devoted to photonic crystals aiming at the creation of novel devices which can control light propagation. In the present work, two-dimensional (2D and three-dimensional (3D devices based on nanostructured porous silicon have been fabricated. 2D devices consist of a square mesh of 2 μm wide porous silicon veins, leaving 5×5 μm square air holes. 3D structures share the same design although multilayer porous silicon veins are used instead, providing an additional degree of modulation. These devices are fabricated from porous silicon single layers (for 2D structures or multilayers (for 3D structures, opening air holes in them by means of 1 KeV argon ion bombardment through the appropriate copper grids. For 2D structures, a complete photonic band gap for TE polarization is found in the thermal infrared range. For 3D structures, there are no complete band gaps, although several new partial gaps do exist in different high-symmetry directions. The simulation results suggest that these structures are very promising candidates for the development of low-cost photonic devices for their use in the thermal infrared range.

  6. Reduction of multi-dimensional laboratory data to a two-dimensional plot: a novel technique for the identification of laboratory error.

    Science.gov (United States)

    Kazmierczak, Steven C; Leen, Todd K; Erdogmus, Deniz; Carreira-Perpinan, Miguel A

    2007-01-01

    The clinical laboratory generates large amounts of patient-specific data. Detection of errors that arise during pre-analytical, analytical, and post-analytical processes is difficult. We performed a pilot study, utilizing a multidimensional data reduction technique, to assess the utility of this method for identifying errors in laboratory data. We evaluated 13,670 individual patient records collected over a 2-month period from hospital inpatients and outpatients. We utilized those patient records that contained a complete set of 14 different biochemical analytes. We used two-dimensional generative topographic mapping to project the 14-dimensional record to a two-dimensional space. The use of a two-dimensional generative topographic mapping technique to plot multi-analyte patient data as a two-dimensional graph allows for the rapid identification of potentially anomalous data. Although we performed a retrospective analysis, this technique has the benefit of being able to assess laboratory-generated data in real time, allowing for the rapid identification and correction of anomalous data before they are released to the physician. In addition, serial laboratory multi-analyte data for an individual patient can also be plotted as a two-dimensional plot. This tool might also be useful for assessing patient wellbeing and prognosis.

  7. Syntheses, structures and properties of three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers based on 2,2'-dipyridyl-5,5'-dicarboxylate ligands.

    Science.gov (United States)

    Zhao, Junwei; Cheng, Yamin; Shang, Sensen; Zhang, Fang; Chen, Li; Chen, Lijuan

    2013-12-01

    Three new two-dimensional Cu(I)-Ln(III) heterometallic coordination polymers [Ln(III)Cu2(I)(Hbpdc)4] · Cl · xH2O [Ln(III) = La(III), x = 8 (1); Ln(III) = Pr(III), x=9 (2); Ln(III) = Eu(III), x = 8 (3)] (H2bpdc = 2,2'-bipyridyl-5,5'-dicarboxylic acid) have been prepared under hydrothermal conditions and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. X-ray diffraction indicates that the isomorphic 1-3 display the two-dimensional sheet structure constructed from [Cu(I)(Hbpdc)2](-) fragments through Ln(3+) connectors. Moreover, the solid-state photoluminescence measurements of 3 indicate that the Eu(III) ions, Hbpdc(-) ligands and Cu(I) cations make contributions to its luminescent properties simultaneously. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Measurement of time-dependent $CP$ violation in charmless two-body $B$ decays

    CERN Document Server

    The LHCb Collaboration

    2012-01-01

    Using an integrated luminosity of 0.69~fb$^{-1}$ collected by LHCb in 2011, we report measurements of direct and mixing-induced $C\\!P$ violation in $B^0\\to\\pi^+\\pi^-$ and $B^0_s\\to K^+K^-$ decays. We obtain \\begin{equation*} \\begin{split} A^{\\rm dir}_{\\pi\\pi} = 0.11 \\pm 0.21 \\pm 0.03,\\\\ A^{\\rm mix}_{\\pi\\pi} = -0.56 \\pm 0.17 \\pm 0.03,\\\\ A^{\\rm dir}_{KK} = 0.02 \\pm 0.18 \\pm 0.04,\\\\ A^{\\rm mix}_{KK} = 0.17 \\pm 0.18 \\pm 0.05, \\end{split} \\end{equation*} where the first uncertainties are statistical and the second systematic. The correlations are found to be $\\rho (A^{\\rm dir}_{\\pi\\pi},\\,A^{\\rm mix}_{\\pi\\pi})=-0.34$ and $\\rho(A^{\\rm dir}_{KK},\\,A^{\\rm mix}_{KK})=-0.10$. The measurements of $A^{\\rm dir}_{\\pi\\pi}$ and $A^{\\rm mix}_{\\pi\\pi}$ are compatible with those from the $B$ factories and yield 3.2$\\sigma$ evidence of mixing-induced $C\\!P$ violation, whereas $A^{\\rm dir}_{KK}$ and $A^{\\rm mix}_{KK}$ are measured for the first time ever.

  9. Resonance fluorescence based two- and three-dimensional atom localization

    Science.gov (United States)

    Wahab, Abdul; Rahmatullah; Qamar, Sajid

    2016-06-01

    Two- and three-dimensional atom localization in a two-level atom-field system via resonance fluorescence is suggested. For the two-dimensional localization, the atom interacts with two orthogonal standing-wave fields, whereas for the three-dimensional atom localization, the atom interacts with three orthogonal standing-wave fields. The effect of the detuning and phase shifts associated with the corresponding standing-wave fields is investigated. A precision enhancement in position measurement of the single atom can be noticed via the control of the detuning and phase shifts.

  10. Toward two-dimensional search engines

    International Nuclear Information System (INIS)

    Ermann, L; Shepelyansky, D L; Chepelianskii, A D

    2012-01-01

    We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way, the ranking of nodes becomes two dimensional which paves the way for the development of two-dimensional search engines of a new type. Statistical properties of information flow on the PageRank–CheiRank plane are analyzed for networks of British, French and Italian universities, Wikipedia, Linux Kernel, gene regulation and other networks. A special emphasis is done for British universities networks using the large database publicly available in the UK. Methods of spam links control are also analyzed. (paper)

  11. Infrared Range Sensor Array for 3D Sensing in Robotic Applications

    Directory of Open Access Journals (Sweden)

    Yongtae Do

    2013-04-01

    Full Text Available This paper presents the design and testing of multiple infrared range detectors arranged in a two-dimensional (2D array. The proposed system can collect the sparse three-dimensional (3D data of objects and surroundings for robotics applications. Three kinds of tasks are considered using the system: detecting obstacles that lie ahead of a mobile robot, sensing the ground profile for the safe navigation of a mobile robot, and sensing the shape and position of an object on a conveyor belt for pickup by a robot manipulator. The developed system is potentially a simple alternative to high-resolution (and expensive 3D sensing systems, such as stereo cameras or laser scanners. In addition, the system can provide shape information about target objects and surroundings that cannot be obtained using simple ultrasonic sensors. Laboratory prototypes of the system were built with nine infrared range sensors arranged in a 3×3 array and test results confirmed the validity of system.

  12. Subjective figure reversal in two- and three-dimensional perceptual space.

    Science.gov (United States)

    Radilová, J; Radil-Weiss, T

    1984-08-01

    A permanently illuminated pattern of Mach's truncated pyramid can be perceived according to the experimental instruction given, either as a three-dimensional reversible figure with spontaneously changing convex and concave interpretation (in one experiment), or as a two-dimensional reversible figure-ground pattern (in another experiment). The reversal rate was about twice as slow, without the subjects being aware of it, if it was perceived as a three-dimensional figure compared to the situation when it was perceived as two-dimensional. It may be hypothetized that in the three-dimensional case, the process of perception requires more sequential steps than in the two-dimensional one.

  13. Zero-dimensional limit of the two-dimensional Lugiato-Lefever equation

    Science.gov (United States)

    Cardoso, Wesley B.; Salasnich, Luca; Malomed, Boris A.

    2017-05-01

    We study effects of tight harmonic-oscillator confinement on the electromagnetic field in a laser cavity by solving the two-dimensional Lugiato-Lefever (2D LL) equation, taking into account self-focusing or defocusing nonlinearity, losses, pump, and the trapping potential. Tightly confined (quasi-zero-dimensional) optical modes (pixels), produced by this model, are analyzed by means of the variational approximation, which provides a qualitative picture of the ensuing phenomena. This is followed by systematic simulations of the time-dependent 2D LL equation, which reveal the shape, stability, and dynamical behavior of the resulting localized patterns. In this way, we produce stability diagrams for the expected pixels. Then, we consider the LL model with the vortical pump, showing that it can produce stable pixels with embedded vorticity (vortex solitons) in remarkably broad stability areas. Alongside confined vortices with the simple single-ring structure, in the latter case the LL model gives rise to stable multi-ring states, with a spiral phase field. In addition to the numerical results, a qualitatively correct description of the vortex solitons is provided by the Thomas-Fermi approximation. Contribution to the Topical Issue: "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  14. Face recognition based on two-dimensional discriminant sparse preserving projection

    Science.gov (United States)

    Zhang, Dawei; Zhu, Shanan

    2018-04-01

    In this paper, a supervised dimensionality reduction algorithm named two-dimensional discriminant sparse preserving projection (2DDSPP) is proposed for face recognition. In order to accurately model manifold structure of data, 2DDSPP constructs within-class affinity graph and between-class affinity graph by the constrained least squares (LS) and l1 norm minimization problem, respectively. Based on directly operating on image matrix, 2DDSPP integrates graph embedding (GE) with Fisher criterion. The obtained projection subspace preserves within-class neighborhood geometry structure of samples, while keeping away samples from different classes. The experimental results on the PIE and AR face databases show that 2DDSPP can achieve better recognition performance.

  15. Two multi-dimensional uncertainty relations

    International Nuclear Information System (INIS)

    Skala, L; Kapsa, V

    2008-01-01

    Two multi-dimensional uncertainty relations, one related to the probability density and the other one related to the probability density current, are derived and discussed. Both relations are stronger than the usual uncertainty relations for the coordinates and momentum

  16. (2+1)-dimensional stable spatial Raman solitons

    International Nuclear Information System (INIS)

    Shverdin, M.Y.; Yavuz, D.D.; Walker, D.R.

    2004-01-01

    We analyze the formation, propagation, and interaction of stable two-frequency (2+1)-dimensional solitons, formed in a Raman media driven near maximum molecular coherence. The propagating light is trapped in the two transverse dimensions

  17. Mechanical exfoliation of two-dimensional materials

    Science.gov (United States)

    Gao, Enlai; Lin, Shao-Zhen; Qin, Zhao; Buehler, Markus J.; Feng, Xi-Qiao; Xu, Zhiping

    2018-06-01

    Two-dimensional materials such as graphene and transition metal dichalcogenides have been identified and drawn much attention over the last few years for their unique structural and electronic properties. However, their rise begins only after these materials are successfully isolated from their layered assemblies or adhesive substrates into individual monolayers. Mechanical exfoliation and transfer are the most successful techniques to obtain high-quality single- or few-layer nanocrystals from their native multi-layer structures or their substrate for growth, which involves interfacial peeling and intralayer tearing processes that are controlled by material properties, geometry and the kinetics of exfoliation. This procedure is rationalized in this work through theoretical analysis and atomistic simulations. We propose a criterion to assess the feasibility for the exfoliation of two-dimensional sheets from an adhesive substrate without fracturing itself, and explore the effects of material and interface properties, as well as the geometrical, kinetic factors on the peeling behaviors and the torn morphology. This multi-scale approach elucidates the microscopic mechanism of the mechanical processes, offering predictive models and tools for the design of experimental procedures to obtain single- or few-layer two-dimensional materials and structures.

  18. N-dimensional integrability from two-photon coalgebra symmetry

    International Nuclear Information System (INIS)

    Ballesteros, Angel; Blasco, Alfonso; Herranz, Francisco J

    2009-01-01

    A wide class of Hamiltonian systems with N degrees of freedom and endowed with, at least, (N - 2) functionally independent integrals of motion in involution is constructed by making use of the two-photon Lie-Poisson coalgebra (h 6 , Δ). The set of (N - 2) constants of the motion is shown to be a universal one for all these Hamiltonians, irrespective of the dependence of the latter on several arbitrary functions and N free parameters. Within this large class of quasi-integrable N-dimensional Hamiltonians, new families of completely integrable systems are identified by finding explicitly a new independent integral I through the analysis of the sub-coalgebra structure of h 6 . In particular, new completely integrable N-dimensional Hamiltonians describing natural systems, geodesic flows and static electromagnetic Hamiltonians are presented

  19. Investigation of two different anoxia models by 2-dimensional gel electrophoresis

    DEFF Research Database (Denmark)

    Wulff, Tune; Jessen, Flemming; Hoffmann, Else Kay

    2006-01-01

    anoxia obtained by NaN3 is a widely used model for simulating anoxia (Ossum et al., 2004). The effects of anoxia were studied by protein expression analysis using 2-dimensional gel electrophoresis followed by MS/MS. In this way we were able to separate more than 1500 protein spots with an apparent range...

  20. A two-dimensional, semi-analytic expansion method for nodal calculations

    International Nuclear Information System (INIS)

    Palmtag, S.P.

    1995-08-01

    Most modern nodal methods used today are based upon the transverse integration procedure in which the multi-dimensional flux shape is integrated over the transverse directions in order to produce a set of coupled one-dimensional flux shapes. The one-dimensional flux shapes are then solved either analytically or by representing the flux shape by a finite polynomial expansion. While these methods have been verified for most light-water reactor applications, they have been found to have difficulty predicting the large thermal flux gradients near the interfaces of highly-enriched MOX fuel assemblies. A new method is presented here in which the neutron flux is represented by a non-seperable, two-dimensional, semi-analytic flux expansion. The main features of this method are (1) the leakage terms from the node are modeled explicitly and therefore, the transverse integration procedure is not used, (2) the corner point flux values for each node are directly edited from the solution method, and a corner-point interpolation is not needed in the flux reconstruction, (3) the thermal flux expansion contains hyperbolic terms representing analytic solutions to the thermal flux diffusion equation, and (4) the thermal flux expansion contains a thermal to fast flux ratio term which reduces the number of polynomial expansion functions needed to represent the thermal flux. This new nodal method has been incorporated into the computer code COLOR2G and has been used to solve a two-dimensional, two-group colorset problem containing uranium and highly-enriched MOX fuel assemblies. The results from this calculation are compared to the results found using a code based on the traditional transverse integration procedure

  1. Two-dimensional grating guided-mode resonance tunable filter.

    Science.gov (United States)

    Kuo, Wen-Kai; Hsu, Che-Jung

    2017-11-27

    A two-dimensional (2D) grating guided-mode resonance (GMR) tunable filter is experimentally demonstrated using a low-cost two-step nanoimprinting technology with a one-dimensional (1D) grating polydimethylsiloxane mold. For the first nanoimprinting, we precisely control the UV LED irradiation dosage and demold the device when the UV glue is partially cured and the 1D grating mold is then rotated by three different angles, 30°, 60°, and 90°, for the second nanoimprinting to obtain 2D grating structures with different crossing angles. A high-refractive-index film ZnO is then coated on the surface of the grating structure to form the GMR filter devices. The simulation and experimental results demonstrate that the passband central wavelength of the filter can be tuned by rotating the device to change azimuth angle of the incident light. We compare these three 2D GMR filters with differential crossing angles and find that the filter device with a crossing angle of 60° exhibits the best performance. The tunable range of its central wavelength is 668-742 nm when the azimuth angle varies from 30° to 90°.

  2. Two-dimensional filtering of SPECT images using the Metz and Wiener filters

    International Nuclear Information System (INIS)

    King, M.A.; Schwinger, R.B.; Penney, B.C.; Doherty, P.W.

    1984-01-01

    Presently, single photon emission computed tomographic (SPECT) images are usually reconstructed by arbitrarily selecting a one-dimensional ''window'' function for use in reconstruction. A better method would be to automatically choose among a family of two-dimensional image restoration filters in such a way as to produce ''optimum'' image quality. Two-dimensional image processing techniques offer the advantages of a larger statistical sampling of the data for better noise reduction, and two-dimensional image deconvolution to correct for blurring during acquisition. An investigation of two such ''optimal'' digital image restoration techniques (the count-dependent Metz filter and the Wiener filter) was made. They were applied both as two-dimensional ''window'' functions for preprocessing SPECT images, and for filtering reconstructed images. Their performance was compared by measuring image contrast and per cent fractional standard deviation (% FSD) in multiple-acquisitions of the Jaszczak SPECT phantom at two different count levels. A statistically significant increase in image contrast and decrease in % FSD was observed with these techniques when compared to the results of reconstruction with a ramp filter. The adaptability of the techniques was manifested in a lesser % reduction in % FSD at the high count level coupled with a greater enhancement in image contrast. Using an array processor, processing time was 0.2 sec per image for the Metz filter and 3 sec for the Wiener filter. It is concluded that two-dimensional digital image restoration with these techniques can produce a significant increase in SPECT image quality

  3. Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

    Science.gov (United States)

    Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

    2016-04-15

    Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Doping of two-dimensional MoS2 by high energy ion implantation

    Science.gov (United States)

    Xu, Kang; Zhao, Yuda; Lin, Ziyuan; Long, Yan; Wang, Yi; Chan, Mansun; Chai, Yang

    2017-12-01

    Two-dimensional (2D) materials have been demonstrated to be promising candidates for next generation electronic circuits. Analogues to conventional Si-based semiconductors, p- and n-doping of 2D materials are essential for building complementary circuits. Controllable and effective doping strategies require large tunability of the doping level and negligible structural damage to ultrathin 2D materials. In this work, we demonstrate a doping method utilizing a conventional high-energy ion-implantation machine. Before the implantation, a Polymethylmethacrylate (PMMA) protective layer is used to decelerate the dopant ions and minimize the structural damage to MoS2, thus aggregating the dopants inside MoS2 flakes. By optimizing the implantation energy and fluence, phosphorus dopants are incorporated into MoS2 flakes. Our Raman and high-resolution transmission electron microscopy (HRTEM) results show that only negligibly structural damage is introduced to the MoS2 lattice during the implantation. P-doping effect by the incorporation of p+ is demonstrated by Photoluminescence (PL) and electrical characterizations. Thin PMMA protection layer leads to large kinetic damage but also a more significant doping effect. Also, MoS2 with large thickness shows less kinetic damage. This doping method makes use of existing infrastructures in the semiconductor industry and can be extended to other 2D materials and dopant species as well.

  5. NEAR-INFRARED CIRCULAR AND LINEAR POLARIMETRY OF MONOCEROS R2

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jungmi; Tamura, Motohide [Department of Astronomy, Graduate School of Science, The University of Tokyo, 113-0033 (Japan); Hough, James H. [University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Nagata, Tetsuya [Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Kusakabe, Nobuhiko [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-09-01

    We have conducted simultaneous JHK{sub s}-band imaging circular and linear polarimetry of the Monoceros R2 (Mon R2) cluster. We present results from deep and wide near-infrared linear polarimetry of the Mon R2 region. Prominent and extended polarized nebulosities over the Mon R2 field are revisited, and an infrared reflection nebula associated with the Mon R2 cluster and two local reflection nebulae, vdB 67 and vdB 69, is detected. We also present results from deep imaging circular polarimetry in the same region. For the first time, the observations show relatively high degrees of circular polarization (CP) in Mon R2, with as much as approximately 10% in the K{sub s} band. The maximum CP extent of a ring-like nebula around the Mon R2 cluster is approximately 0.60 pc, while that of a western nebula, around vdB 67, is approximately 0.24 pc. The extended size of the CP is larger than those seen in the Orion region around IRc2, while the maximum degree of CP of ∼10% is smaller than those of ∼17% seen in the Orion region. Nonetheless, both the CP size and degree of this region are among the largest in our infrared CP survey of star-forming regions. We have also investigated the time variability of the degree of the polarization of several infrared sources and found possible variations in three sources.

  6. Diversity and distribution of butterflies (Insecta: Lepidoptera of district Dir lower, Khyber Pukhtoonkhwa, Pakistan

    Directory of Open Access Journals (Sweden)

    Muhammad Inayatullah Khan

    2016-03-01

    Full Text Available Butterflies are the fine-looking creatures and act as ecological indicators and pollinators. The present study is the first record of Butterfly fauna of Dir lower. Collection was carried out during March - August 2013. The specimens were collected and identified with the help of taxonomic keys and preserved specimens in National Insect Museum Islamabad. The collection of 375 specimens were preserved. Identification revealed 24 species belonging to 20 genera and 7 families. The species are Papilio polyctor Boisduval, Papilio demoleus Linnaeus, Junonia almanac Linnaeus, Pararge schakra Kollar, Junonia hierta Fabricius, Junonia orythea Linnaeus, Argyrius hyperbius Linnaeus, Hypolimnus bolina Linnaeus, Vanessa cashmiriensis Kollar, Phalantha phalantha Drury, Melitea didyma Esper, Lycaena phalaeas Linnaeus, Lybithea lipita Moore, Danius chrysippus Linnaeus, Hipparchia parasitas Kollar, Lethe rohria Fabricius, Maniola davendra Moore, Pontia daplidice Linnaeus, Belenois aurota Fabricius, Pieris brassicae Linnaeus, Colias erate Esper, Eurema hecabe Linnaeus, Colias fieldi Linnaeus and Cynthia cardui Linnaeus. The highest population was shown by Pieris brassicae followed by Danius chrysippus and Cynthia cardui. Twelve species belong to family Nymphalidae (50%, which shows the highest abundance rate. Butterfly density was the highest at Timergara. Butterfly fauna was the highest in May followed by August and lowest in March. It is concluded that pollution free environment of Dir Lower is more suitable for the survival of butterfly fauna. Large scale study is required to fully explore the butterfly fauna of the area.

  7. Infrared Spectroscopy of Two Isomers of the OCS-CS_{2} Complex

    Science.gov (United States)

    Oliaee, J. N.; Dehghany, M.; Afshari, Mahin; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2009-06-01

    A second isomer of OCS-CS_{2} complex, with a nonplanar cross-shaped structure, has been studied for the first time by analysing an infrared band in the region of the OCS stretching vibration (2062 cm^{-1}). This isomer has C_{s} symmetry and the observed band consists of purely c-type rotational transitions. The ground state rotational parameters are found to be A=0.07306 cm^{-1}, B=0.03325 cm^{-1} and C=0.02879 cm^{-1}, in good agreement with a previous semi-empirical calculation. In addition, a hybrid band with a- and b-type rotational transitions has been assigned to be due to the known planar form of OCS-CS_{2}, as previously studied by microwave spectroscopy. The spectra were recorded using a rapid-scan tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. Calculations indicate that the planar isomer of OCS-CS_{2} is the lowest in energy, in contrast to CO_{2}-CS_{2} where the crossed form is believed to be the lowest. J. J. Newby, M. M. Serafin, R. A. Peebles and S. A. Peebles, Phys. Chem. Chem. Phys. 7, 487 (2005). C. C. Dutton, D. A. Dows, R. Eikey, S. Evans and R. A. Beaudet, J. Phys. Chem. A 102, 6904 (1998).

  8. Study of two-dimensional interchange turbulence

    International Nuclear Information System (INIS)

    Sugama, Hideo; Wakatani, Masahiro.

    1990-04-01

    An eddy viscosity model describing enstrophy transfer in two-dimensional turbulence is presented. This model is similar to that of Canuto et al. and provides an equation for the energy spectral function F(k) as a function of the energy input rate to the system per unit wavenumber, γ s (k). In the enstrophy-transfer inertial range, F(k)∝ k -3 is predicted by the model. The eddy viscosity model is applied to the interchange turbulence of a plasma in shearless magnetic field. Numerical simulation of the two-dimensional interchange turbulence demonstrates that the energy spectrum in the high wavenumber region is well described by this model. The turbulent transport driven by the interchange turbulence is expressed in terms of the Nusselt number Nu, the Rayleigh number Ra and Prantl number Pr in the same manner as that of thermal convection problem. When we use the linear growth rate for γ s (k), our theoretical model predicts that Nu ∝ (Ra·Pr) 1/2 for a constant background pressure gradient and Nu ∝ (Ra·Pr) 1/3 for a self-consistent background pressure profile with the stress-free slip boundary conditions. The latter agrees with our numerical result showing Nu ∝ Ra 1/3 . (author)

  9. Converting Panax ginseng DNA and chemical fingerprints into two-dimensional barcode.

    Science.gov (United States)

    Cai, Yong; Li, Peng; Li, Xi-Wen; Zhao, Jing; Chen, Hai; Yang, Qing; Hu, Hao

    2017-07-01

    In this study, we investigated how to convert the Panax ginseng DNA sequence code and chemical fingerprints into a two-dimensional code. In order to improve the compression efficiency, GATC2Bytes and digital merger compression algorithms are proposed. HPLC chemical fingerprint data of 10 groups of P. ginseng from Northeast China and the internal transcribed spacer 2 (ITS2) sequence code as the DNA sequence code were ready for conversion. In order to convert such data into a two-dimensional code, the following six steps were performed: First, the chemical fingerprint characteristic data sets were obtained through the inflection filtering algorithm. Second, precompression processing of such data sets is undertaken. Third, precompression processing was undertaken with the P. ginseng DNA (ITS2) sequence codes. Fourth, the precompressed chemical fingerprint data and the DNA (ITS2) sequence code were combined in accordance with the set data format. Such combined data can be compressed by Zlib, an open source data compression algorithm. Finally, the compressed data generated a two-dimensional code called a quick response code (QR code). Through the abovementioned converting process, it can be found that the number of bytes needed for storing P. ginseng chemical fingerprints and its DNA (ITS2) sequence code can be greatly reduced. After GTCA2Bytes algorithm processing, the ITS2 compression rate reaches 75% and the chemical fingerprint compression rate exceeds 99.65% via filtration and digital merger compression algorithm processing. Therefore, the overall compression ratio even exceeds 99.36%. The capacity of the formed QR code is around 0.5k, which can easily and successfully be read and identified by any smartphone. P. ginseng chemical fingerprints and its DNA (ITS2) sequence code can form a QR code after data processing, and therefore the QR code can be a perfect carrier of the authenticity and quality of P. ginseng information. This study provides a theoretical

  10. Applying dual-laser spot positions measurement technology on a two-dimensional tracking measurement system

    International Nuclear Information System (INIS)

    Lee, Hau-Wei; Chen, Chieh-Li

    2009-01-01

    This paper presents a two-dimensional tracking measurement system with a tracking module, which consists of two stepping motors, two laser diodes and a four separated active areas segmented position sensitive detector (PSD). The PSD was placed on a two-dimensional moving stage and used as a tracking target. The two laser diodes in the tracking module were directly rotated to keep the laser spots on the origin of the PSD. The two-dimensional position of the target PSD on the moving stage is determined from the distance between the two motors and the tracking angles of the two laser diodes, which are rotated by the two stepping motors, respectively. In order to separate the four positional values of the two laser spots on one PSD, the laser diodes were modulated by two distinct frequencies. Multiple-laser spot position measurement technology was used to separate the four positional values of the two laser spots on the PSD. The experimental results show that the steady-state voltage shift rate is about 0.2% and dynamic cross-talk rate is smaller than 2% when the two laser spots are projected on one PSD at the same time. The measurement errors of the x and y axial positions of the two-dimensional tracking system were less than 1% in the measuring range of 20 mm. The results demonstrate that multiple-laser spot position measurement technology can be employed in a two-dimensional tracking measurement system

  11. Bi[NC{sub 5}H{sub 3}(CO{sub 2}){sub 2}](OH{sub 2}){sub x}F (x=1 and 2): New one-dimensional Bi-coordination materials-Reversible hydration and topotactic decomposition to {alpha}-Bi{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Hye Rim [Department of Chemistry Education, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Lee, Dong Woo [Department of Chemistry, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Ok, Kang Min, E-mail: kmok@cau.ac.kr [Department of Chemistry, Chung-Ang University, Seoul 156-756 (Korea, Republic of)

    2012-03-15

    Two one-dimensional bismuth-coordination materials, Bi[NC{sub 5}H{sub 3}(CO{sub 2}){sub 2}](OH{sub 2}){sub x}F (x=1 and 2), have been synthesized by hydrothermal reactions using Bi{sub 2}O{sub 3}, 2,6-NC{sub 5}H{sub 3}(CO{sub 2}H){sub 2}, HF, and water at 180 Degree-Sign C. Structures of the two materials were determined by single-crystal X-ray diffraction. Although they have different crystal structures, both Bi-organic materials shared a common structural motif, a one-dimensional chain structure consisting of Bi{sup 3+} cations and pyridine dicarboxylate linkers. Detailed structural analyses include infrared spectroscopy, thermogravimetric analysis, and reversible hydration reactions for the coordinated water molecules were reported. Also, thermal decomposition of the rod-shaped Bi[NC{sub 5}H{sub 3}(CO{sub 2}){sub 2}](OH{sub 2})F single crystals at 800 Degree-Sign C led to {alpha}-Bi{sub 2}O{sub 3} that maintained the same morphology of the original crystals. - Graphical abstract: Calcination of the Bi[NC{sub 5}H{sub 3}(CO{sub 2}){sub 2}](OH{sub 2})F single crystals at 800 Degree-Sign C results in the {alpha}-Bi{sub 2}O{sub 3} rods that maintain the original morphology of the crystals. Highlights: Black-Right-Pointing-Pointer Synthesis of one-dimensional chain Bi-organic frameworks. Black-Right-Pointing-Pointer Reversible hydration reactions of Bi[NC{sub 5}H{sub 3}(CO{sub 2}){sub 2}](OH{sub 2})F. Black-Right-Pointing-Pointer Topotactic decomposition maintaining the same morphology of the original crystals.

  12. Two Dimensional Electrophoresis of Galactosidase Relating to the Disappearance of Bombyx Lectin Activity

    OpenAIRE

    カトウ, ヤスオ; Yasuo, Kato

    2004-01-01

    "Two dimensional polyacrylamide gel electroporesis (2 D-PAGE) analysis on the haemolymph of Bombyx mori was performed using the Mini-PROTEAN mini tube gel two dimensional polyacrylamide gel electrophoresis system (Bio-Rad Laboratories, Inc.). The result on various electrophoretical conditions using the haemolymph-protein showed the possibility that the haemolymph-protein was separated actually by means of this method. Moreover, the result of 2 D-PAGE analysis on Fraction II obtained by gel fi...

  13. Mechanical stretching for tissue engineering: two-dimensional and three-dimensional constructs.

    Science.gov (United States)

    Riehl, Brandon D; Park, Jae-Hong; Kwon, Il Keun; Lim, Jung Yul

    2012-08-01

    Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols.

  14. Prenatal diagnosis of sirenomelia by two-dimensional and three-dimensional skeletal imaging ultrasound.

    Science.gov (United States)

    Liu, Rong; Chen, Xin-lin; Yang, Xiao-hong; Ma, Hui-jing

    2015-12-01

    This study sought to evaluate the contribution of two-dimensional ultrasound (2D-US) and three-dimensional skeletal imaging ultrasound (3D-SUIS) in the prenatal diagnosis of sirenomelia. Between September 2010 and April 2014, a prospective study was conducted in a single referral center using 3D-SUIS performed after 2D-US in 10 cases of sirenomelia. Diagnostic accuracy and detailed findings were compared with postnatal three-dimensional helical computed tomography (3D-HCT), radiological findings and autopsy. Pregnancy was terminated in all 10 sirenomelia cases, including 9 singletons and 1 conjoined twin pregnancy, for a total of 5 males and 5 females. These cases of sirenomelia were determined by autopsy and/or chromosomal examination. Initial 2D-US showed that there were 10 cases of oligohydramnios, bilateral renal agenesis, bladder agenesis, single umbilical artery, fusion of the lower limbs and spinal abnormalities; 8 cases of dipus or monopus; 2 cases of apus; and 8 cases of cardiac abnormalities. Subsequent 3D-SUIS showed that there were 9 cases of scoliosis, 10 cases of sacrococcygeal vertebra dysplasia, 3 cases of hemivertebra, 1 case of vertebral fusion, 3 cases of spina bifida, and 5 cases of rib abnormalities. 3D-SUIS identified significantly more skeletal abnormalities than did 2D-US, and its accuracy was 79.5% (70/88) compared with 3D-HCT and radiography. 3D-SUIS seems to be a useful complementary method to 2D-US and may improve the accuracy of identifying prenatal skeletal abnormalities related to sirenomelia.

  15. Two-dimensional Potts antiferromagnets with a phase transition at arbitrarily large q

    Czech Academy of Sciences Publication Activity Database

    Huang, Y.; Chen, K.; Deng, Y.; Jacobsen, J. L.; Kotecký, R.; Salas, J.; Sokal, Alan D.; Swart, Jan M.

    2013-01-01

    Roč. 87, Č. 1 (2013), 12136-1-12136-5 ISSN 1539-3755 R&D Projects: GA ČR GAP201/12/2613 Institutional support: RVO:67985556 Keywords : Monte Carlo simulation * two-dimensional lattices * q-state Potts Subject RIV: BE - Theoretical Physics Impact factor: 2.326, year: 2013 http://library.utia.cas.cz/separaty/2013/SI/swart-two-dimensional potts antiferromagnets with a phase transition at arbitrarily large q.pdf

  16. Two-dimensional materials for ultrafast lasers

    International Nuclear Information System (INIS)

    Wang Fengqiu

    2017-01-01

    As the fundamental optical properties and novel photophysics of graphene and related two-dimensional (2D) crystals are being extensively investigated and revealed, a range of potential applications in optical and optoelectronic devices have been proposed and demonstrated. Of the many possibilities, the use of 2D materials as broadband, cost-effective and versatile ultrafast optical switches (or saturable absorbers) for short-pulsed lasers constitutes a rapidly developing field with not only a good number of publications, but also a promising prospect for commercial exploitation. This review primarily focuses on the recent development of pulsed lasers based on several representative 2D materials. The comparative advantages of these materials are discussed, and challenges to practical exploitation, which represent good future directions of research, are laid out. (paper)

  17. Two-dimensional dynamics of a free molecular chain with a secondary structure

    DEFF Research Database (Denmark)

    Zolotaryuk, Alexander; Christiansen, Peter Leth; Savin, A.V.

    1996-01-01

    A simple two-dimensional (2D) model of an isolated (free) molecular chain with primary and secondary structures has been suggested and investigated both analytically and numerically. This model can be considered as the simplest generalization of the well-known Fermi-Pasta-Ulam model of an anharmo......A simple two-dimensional (2D) model of an isolated (free) molecular chain with primary and secondary structures has been suggested and investigated both analytically and numerically. This model can be considered as the simplest generalization of the well-known Fermi-Pasta-Ulam model...

  18. Fingerprints of field-induced Berezinskii–Kosterlitz–Thouless transition in quasi-two-dimensional S=1/2 Heisenberg magnets Cu(en)(H{sub 2}O){sub 2}SO{sub 4} and Cu(tn)Cl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Baranová, Lucia [Civil Engineering Faculty, Department of Applied Mathematics, Technical University of Košice, Vysokoškolská 4 SK-042 00, Košice (Slovakia); Orendáčová, Alžbeta, E-mail: alzbeta.orendacova@upjs.sk [Center of Low Temperature Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9 SK-041 54, Košice (Slovakia); Čižmár, Erik [Center of Low Temperature Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9 SK-041 54, Košice (Slovakia); Tarasenko, Róbert; Tkáč, Vladimír [Center of Low Temperature Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9 SK-041 54, Košice (Slovakia); Charles University, Faculty of Mathematics and Physics, Ke Karlovu 5 12116, Prague (Czech Republic); Orendáč, Martin; Feher, Alexander [Center of Low Temperature Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9 SK-041 54, Košice (Slovakia)

    2016-04-15

    Organo-metallic compounds Cu(en)(H{sub 2}O){sub 2}SO{sub 4} (en=C{sub 2}H{sub 8}N{sub 2}) and Cu(tn)Cl{sub 2} (tn=C{sub 3}H{sub 10}N{sub 2}) representing S=1/2 quasi-two-dimensional Heisenberg antiferromagnets with an effective intra-layer exchange coupling J/k{sub B}≈3 K, have been examined by specific heat measurements at temperatures down to nominally 50 mK and magnetic fields up to 14 T. A comparative analysis of magnetic specific heat in zero magnetic field revealed nearly identical contribution of short-range magnetic correlations and significant differences were observed at lowest temperatures. A phase transition to long-range order was observed in Cu(en)(H{sub 2}O){sub 2}SO{sub 4} at T{sub C}=0.9 K while hidden in Cu(tn)Cl{sub 2}. A response of both compounds to the application of magnetic field has rather universal features characteristic for a field-induced Berezinskii–Kosterlitz–Thouless transition theoretically predicted for ideal two-dimensional magnets. - Highlights: • Magnetic specific heat of Cu(en)(H{sub 2}O){sub 2}SO{sub 4} (1) and Cu(tn)Cl{sub 2} (2) was analysed. • In zero magnetic field, (1) and (2) behave as quasi-two-dimensional magnets. • We observed universal thermodynamic response of (1) and (2) to applied field. • Features of field-induced Berezinskii–Kosterlitz–Thouless transition were detected.

  19. Spin dynamics in a two-dimensional quantum gas

    DEFF Research Database (Denmark)

    Pedersen, Poul Lindholm; Gajdacz, Miroslav; Deuretzbacher, Frank

    2014-01-01

    We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimp......We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions...

  20. One and two dimensional simulations on beat wave acceleration

    International Nuclear Information System (INIS)

    Mori, W.; Joshi, C.; Dawson, J.M.; Forslund, D.W.; Kindel, J.M.

    1984-01-01

    Recently there has been considerable interest in the use of fast-large-amplitude plasma waves as the basis for a high energy particle accelerator. In these schemes, lasers are used to create the plasma wave. To date the few simulation studies on this subject have been limited to one-dimensional, short rise time simulations. Here the authors present results from simulations in which more realistic parameters are used. In addition, they present the first two dimensional simulations on this subject. One dimensional simulations on a 2 1/2-D relativistic electromagnetic particle code, in which only a few cells were used in one direction, on colinear optical mixing are presented. In these simulations the laser rise time, laser intensity, plasma density, plasma temperature and system size were varied. The simulations indicate that the theory of Rosenbluth and Liu is applicable over a wide range of parameters. In addition, simulations with a DC magnetic field are presented in order to study the ''Surfatron'' concept

  1. Two dimensional nanomaterials for flexible supercapacitors.

    Science.gov (United States)

    Peng, Xu; Peng, Lele; Wu, Changzheng; Xie, Yi

    2014-05-21

    Flexible supercapacitors, as one of most promising emerging energy storage devices, are of great interest owing to their high power density with great mechanical compliance, making them very suitable as power back-ups for future stretchable electronics. Two-dimensional (2D) nanomaterials, including the quasi-2D graphene and inorganic graphene-like materials (IGMs), have been greatly explored to providing huge potential for the development of flexible supercapacitors with higher electrochemical performance. This review article is devoted to recent progresses in engineering 2D nanomaterials for flexible supercapacitors, which survey the evolution of electrode materials, recent developments in 2D nanomaterials and their hybrid nanostructures with regulated electrical properties, and the new planar configurations of flexible supercapacitors. Furthermore, a brief discussion on future directions, challenges and opportunities in this fascinating area is also provided.

  2. Two dimensional crystals of LH2 light-harvesting complexes from Ectothiorhodospira sp. and Rhodobacter capsulatus investigated by electron microscopy

    NARCIS (Netherlands)

    Oling, Frank; Boekema, EJ; deZarate, IO; Visschers, R; vanGrondelle, R; Keegstra, W; Brisson, A; Picorel, R

    1996-01-01

    Two-dimensional crystals of LH2 (B800-850) light-harvesting complexes from Ectothiorhodospira sp, and Rhodobacter capsulatus were obtained by reconstitution of purified protein into phospholipid vesicles and characterized by electron microscopy. The size of the crystals was up to several

  3. Two-dimensional crystals of LH2 light-harvesting complexes from Ectothiorhodospira sp. and Rhodobacter capsulatus investigated by electron microscopy.

    NARCIS (Netherlands)

    Oling, F.; Boekema, E.J.; Ortiz de Zarate, I.; Visschers, R.W.; van Grondelle, R.; Keegstra, W.; Brisson, A.; Picorel, R.

    1996-01-01

    Two-dimensional crystals of LH2 (B800-850) light-harvesting complexes from Ectothiorhodospira sp. and Rhodobacter capsulatus were obtained by reconstitution of purified protein into phospholipid vesicles and characterized by electron microscopy. The size of the crystals was up to several

  4. Enhanced thermoelectric power in two-dimensional transition metal dichalcogenide monolayers

    KAUST Repository

    Pu, Jiang

    2016-07-27

    The carrier-density-dependent conductance and thermoelectric properties of large-area MoS2 and WSe2 monolayers are simultaneously investigated using the electrolyte gating method. The sign of the thermoelectric power changes across the transistor off-state in the ambipolar WSe2 transistor as the majority carrier density switches from electron to hole. The thermopower and thermoelectric power factor of monolayer samples are one order of magnitude larger than that of bulk materials, and their carrier-density dependences exhibit a quantitative agreement with the semiclassical Mott relation based on the two-dimensional energy band structure, concluding the thermoelectric properties are enhanced by the low-dimensional effect.

  5. Sarah Sepulchre, dir. Décoder les séries télévisées.

    Directory of Open Access Journals (Sweden)

    Jan Baetens

    2011-08-01

    Full Text Available

    Sarah Sepulchre, dir. Décoder les séries télévisées.

    Bruxelles: De Boeck, coll. InfoCom, 2011-06-22 ISBN 978-2-8041-6375-4

  6. arXiv Supersymmetric gauged matrix models from dimensional reduction on a sphere

    CERN Document Server

    Closset, Cyril; Seong, Rak-Kyeong

    2018-05-04

    It was recently proposed that $ \\mathcal{N} $ = 1 supersymmetric gauged matrix models have a duality of order four — that is, a quadrality — reminiscent of infrared dualities of SQCD theories in higher dimensions. In this note, we show that the zero-dimensional quadrality proposal can be inferred from the two-dimensional Gadde-Gukov-Putrov triality. We consider two-dimensional $ \\mathcal{N} $ = (0, 2) SQCD compactified on a sphere with the half-topological twist. For a convenient choice of R-charge, the zero-mode sector on the sphere gives rise to a simple $ \\mathcal{N} $ = 1 gauged matrix model. Triality on the sphere then implies a triality relation for the supersymmetric matrix model, which can be completed to the full quadrality.

  7. Quantum oscillations in quasi-two-dimensional conductors

    CERN Document Server

    Galbova, O

    2002-01-01

    The electronic absorption of sound waves in quasi-two-dimensional conductors in strong magnetic fields, is investigated theoretically. A longitudinal acoustic wave, propagating along the normal n-> to the layer of quasi-two-dimensional conductor (k-> = left brace 0,0,k right brace; u-> = left brace 0,0,u right brace) in magnetic field (B-> = left brace 0, 0, B right brace), is considered. The quasiclassical approach for this geometry is of no interest, due to the absence of interaction between electromagnetic and acoustic waves. The problem is of interest in strong magnetic field when quantization of the charge carriers energy levels takes place. The quantum oscillations in the sound absorption coefficient, as a function of the magnetic field, are theoretically observed. The experimental study of the quantum oscillations in quasi-two-dimensional conductors makes it possible to solve the inverse problem of determining from experimental data the extrema closed sections of the Fermi surface by a plane p sub z = ...

  8. A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part Two: Multi-Dimensional Analysis †

    OpenAIRE

    Vincent Casseau; Daniel E. R. Espinoza; Thomas J. Scanlon; Richard E. Brown

    2016-01-01

    hy2Foam is a newly-coded open-source two-temperature computational fluid dynamics (CFD) solver that has previously been validated for zero-dimensional test cases. It aims at (1) giving open-source access to a state-of-the-art hypersonic CFD solver to students and researchers; and (2) providing a foundation for a future hybrid CFD-DSMC (direct simulation Monte Carlo) code within the OpenFOAM framework. This paper focuses on the multi-dimensional verification of hy2Foam and firstly describes th...

  9. Third sound in one and two dimensional modulated structures

    International Nuclear Information System (INIS)

    Komuro, T.; Kawashima, H., Shirahama, K.; Kono, K.

    1996-01-01

    An experimental technique is developed to study acoustic transmission in one and two dimensional modulated structures by employing third sound of a superfluid helium film. In particular, the Penrose lattice, which is a two dimensional quasiperiodic structure, is studied. In two dimensions, the scattering of third sound is weaker than in one dimension. Nevertheless, the authors find that the transmission spectrum in the Penrose lattice, which is a two dimensional prototype of the quasicrystal, is observable if the helium film thickness is chosen around 5 atomic layers. The transmission spectra in the Penrose lattice are explained in terms of dynamical theory of diffraction

  10. Bounds on the Capacity of Weakly constrained two-dimensional Codes

    DEFF Research Database (Denmark)

    Forchhammer, Søren

    2002-01-01

    Upper and lower bounds are presented for the capacity of weakly constrained two-dimensional codes. The maximum entropy is calculated for two simple models of 2-D codes constraining the probability of neighboring 1s as an example. For given models of the coded data, upper and lower bounds...... on the capacity for 2-D channel models based on occurrences of neighboring 1s are considered....

  11. Observation of exchange of micropore water in cement pastes by two-dimensional T(2)-T(2) nuclear magnetic resonance relaxometry.

    Science.gov (United States)

    Monteilhet, L; Korb, J-P; Mitchell, J; McDonald, P J

    2006-12-01

    The first detailed analysis of the two-dimensional (2D) NMR T(2)-T(2) exchange experiment with a period of magnetization storage between the two T(2) relaxation encoding periods (T(2)-store-T(2)) is presented. It is shown that this experiment has certain advantages over the T(1)-T(2) variant for the quantization of chemical exchange. New T(2)-store-T(2) 2D 1H NMR spectra of the pore water within white cement paste are presented. Based on these spectra, the exchange rate of water between the two smallest porosity reservoirs is estimated for the first time. It is found to be of the order of 5 ms{-1}. Further, a careful estimate of the pore sizes of these reservoirs is made. They are found to be of the order of 1.4 nm and 10-30 nm , respectively. A discussion of the results is developed in terms of possible calcium silicate hydrate products. A water diffusion coefficient inferred from the exchange rate and the cement particle size is found to compare favorably with the results of molecular-dynamics simulations to be found in the literature.

  12. SONATINA-2V: a computer program for seismic analysis of the two-dimensional vertical slice HTGR core

    International Nuclear Information System (INIS)

    Ikushima, Takeshi

    1982-07-01

    A computer program SONATINA-2V has been developed for predicting the behavior of a two-dimensional vertical slice HTGR core under seismic excitation. SONATINA-2V is a general two-dimensional computer program capable of analyzing the vertical slice HTGR core with the permanent side reflector blocks and its restraint structures. In the analytical model, each block is treated as rigid body and is restrained by dowel pins which restrict relative horizontal movement but allow vertical and rocking motions between upper and lower blocks. Coulomb friction is taken into account between blocks and between dowel pin and hole. A spring dashpot model is used for the collision process between adjacent blocks. The core support structure is represented by a single block. The computer program SONATINA-2V is capable of analyzing the core behavior for an excitation input applied simultaneously to both vertical and horizontal directions. Analytical results obtained from SONATINA-2V are compared with experimental results and are found to be in good agreement. The computer program can thus be used to predict with a good accuracy the behavior of the HTGR core under seismic excitation. In the present report are given, the theoretical formulation of the analytical model, a user's manual to describe the input and output format, and sample problems. (author)

  13. Incorrectness of conventional one-dimensional parallel thermal resistance circuit model for two-dimensional circular composite pipes

    International Nuclear Information System (INIS)

    Wong, K.-L.; Hsien, T.-L.; Chen, W.-L.; Yu, S.-J.

    2008-01-01

    This study is to prove that two-dimensional steady state heat transfer problems of composite circular pipes cannot be appropriately solved by the conventional one-dimensional parallel thermal resistance circuits (PTRC) model because its interface temperatures are not unique. Thus, the PTRC model is definitely different from its conventional recognized analogy, parallel electrical resistance circuits (PERC) model, which has unique node electric voltages. Two typical composite circular pipe examples are solved by CFD software, and the numerical results are compared with those obtained by the PTRC model. This shows that the PTRC model generates large error. Thus, this conventional model, introduced in most heat transfer text books, cannot be applied to two-dimensional composite circular pipes. On the contrary, an alternative one-dimensional separately series thermal resistance circuit (SSTRC) model is proposed and applied to a two-dimensional composite circular pipe with isothermal boundaries, and acceptable results are returned

  14. Intertwined Hamiltonians in two-dimensional curved spaces

    International Nuclear Information System (INIS)

    Aghababaei Samani, Keivan; Zarei, Mina

    2005-01-01

    The problem of intertwined Hamiltonians in two-dimensional curved spaces is investigated. Explicit results are obtained for Euclidean plane, Minkowski plane, Poincare half plane (AdS 2 ), de Sitter plane (dS 2 ), sphere, and torus. It is shown that the intertwining operator is related to the Killing vector fields and the isometry group of corresponding space. It is shown that the intertwined potentials are closely connected to the integral curves of the Killing vector fields. Two problems are considered as applications of the formalism presented in the paper. The first one is the problem of Hamiltonians with equispaced energy levels and the second one is the problem of Hamiltonians whose spectrum is like the spectrum of a free particle

  15. Two dimensional nonlinear spectral estimation techniques for breast cancer localization

    Energy Technology Data Exchange (ETDEWEB)

    Stathaki, P T; Constantinides, A G [Signal Processing Section, Department of Electrical and Electronic Engineering, Imperial College, Exhibition Road, London SW7 2BT, UK (United Kingdom)

    1994-12-31

    In this paper the problem of image texture analysis in the presence of noise is examined from a higher-order statistical perspective. The approach taken involves the use of two dimensional second order Volterra filters where the filter weights are derived from third order cumulants of the two dimensional signal. The specific application contained in this contribution is in mammography, an area in which it is difficult to discern the appropriate features. The paper describes the fundamental issues of the various components of the approach. The results of the entire texture modelling, classification and segmentation scheme contained in this paper are very encouraging. 7 refs, 2 figs.

  16. Magnetic Raman Scattering in Two-Dimensional Spin-1/2 Heisenberg Antiferromagnets: Explanation of the Spectral Shape Anomaly

    Science.gov (United States)

    Nori, F.; Merlin, R.; Haas, S.; Sandvick, A.; Dagotto, E.

    1996-03-01

    We calculate(F. Nori, R.Merlin, S. Haas, A.W. Sandvik, and E. Dagotto, Physical Review Letters) 75, 553 (1995). the Raman spectrum of the two-dimensional (2D) spin-1/2 Heisenberg antiferromagnet by exact diagonalization and quantum Monte Carlo techniques on clusters of up to 144 sites. On a 16-site cluster, we consider the phonon-magnon interaction which leads to random fluctuations of the exchange integral. Results are in good agreement with experiments on various high-Tc precursors, such as La_2CuO4 and YBa_2Cu_3O_6.2. In particular, our calculations reproduce the broad lineshape of the two-magnon peak, the asymmetry about its maximum, the existence of spectral weight at high energies, and the observation of nominally forbidden A_1g scattering.

  17. Band Alignment Determination of Two-Dimensional Heterojunctions and Their Electronic Applications

    KAUST Repository

    Chiu, Ming-Hui

    2018-01-01

    Two-dimensional (2D) layered materials such as MoS2 have been recognized as high on-off ratio semiconductors which are promising candidates for electronic and optoelectronic devices. In addition to the use of individual 2D materials, the accelerated

  18. Chiral anomaly, fermionic determinant and two dimensional models

    International Nuclear Information System (INIS)

    Rego Monteiro, M.A. do.

    1985-01-01

    The chiral anomaly in random pair dimension is analysed. This anomaly is perturbatively calculated by dimensional regularization method. A new method for non-perturbative Jacobian calculation of a general chiral transformation, 1.e., finite and non-Abelian, is developed. This method is used for non-perturbative chiral anomaly calculation, as an alternative to bosonization of two-dimensional theories for massless fermions and to study the phenomenum of fermion number fractionalization. The fermionic determinant from two-dimensional quantum chromodynamics is also studied, and calculated, exactly, as in decoupling gauge as with out reference to a particular gauge. (M.C.K.) [pt

  19. Two-dimensional heteroclinic attractor in the generalized Lotka-Volterra system

    Science.gov (United States)

    Afraimovich, Valentin S.; Moses, Gregory; Young, Todd

    2016-05-01

    We study a simple dynamical model exhibiting sequential dynamics. We show that in this model there exist sets of parameter values for which a cyclic chain of saddle equilibria, O k , k=1,\\ldots,p , have two-dimensional unstable manifolds that contain orbits connecting each O k to the next two equilibrium points O k+1 and O k+2 in the chain ({{O}p+1}={{O}1} ). We show that the union of these equilibria and their unstable manifolds form a two-dimensional surface with a boundary that is homeomorphic to a cylinder if p is even and a Möbius strip if p is odd. If, further, each equilibrium in the chain satisfies a condition called ‘dissipativity’, then this surface is asymptotically stable.

  20. Dynamics of a two-dimensional order-disorder transition

    International Nuclear Information System (INIS)

    Sahni, P.S.; Dee, G.; Gunton, J.D.; Phani, M.; Lebowitz, J.L.; Kalos, M.

    1981-01-01

    We present results of a Monte Carlo study of the time development of a two-dimensional order-disorder model binary alloy following a quench to low temperature from a disordered, high-temperature state. The behavior is qualitatively quite similar to that seen in a recent study of a three-dimensional system. The structure function exhibits a scaling of the form K 2 (t)S(k,t) = G(k/K(t)) where the moment K(t) decreases with time approximately like t/sup -1/2/. If one interprets this moment as being inversely proportional to the domain size, the characteristic domain growth rate is proportional to t/sup -1/2/. Additional insight into this time evolution is obtained from studying the development of the short-range order, as well as from monitoring the growth of a compact ordered domain embedded in a region of opposite order. All these results are consistent with the picture of domain growth as proposed by Lifshitz and by Cahn and Allen

  1. Supercapacitors based on two dimensional VO2 nanosheet electrodes in organic gel electrolyte

    KAUST Repository

    Rakhi, R.B.

    2016-10-16

    VO2 is a low band-gap semiconductor with relatively high conductivity among transition metal oxides, which makes it an interesting material for supercapacitor electrode applications. The performance of VO2 as supercapacitor electrode in organic electrolytes has never been reported before. Herein, two-dimensional nanosheets of VO2 are prepared by the simultaneous solution reduction and exfoliation from bulk V2O5 powder by hydrothermal method. A specific capacitance of 405 Fg−1 is achieved for VO2 based supercapacitor in an organic electrolyte, in three electrode configuration. The symmetric capacitor based on VO2 nanosheet electrodes and the liquid organic electrolyte exhibits an energy density of 46 Wh kg−1 at a power density of 1.4 kW kg−1 at a constant current density of 1 Ag−1. Furthermore, flexible solid-state supercapacitors are fabricated using same electrode material and Alumina-silica based gel electrolyte. The solid-state device delivers a specific capacitance of 145 Fg−1 and a device capacitance of 36 Fg−1 at a discharge current density of 1 Ag−1. Series combination of three solid state capacitors is capable of lighting up a red LED for more than 1 minute.

  2. Optical Studies of Excitonic Effects at Two-Dimensional Nanostructure Interfaces

    Science.gov (United States)

    Ajayi, Obafunso Ademilolu

    Atomically thin two-dimensional nanomaterials such as graphene and transition metal dichalcogenides (TMDCs) have seen a rapid growth of exploration since the isolation of monolayer graphene. These materials provide a rich field of study for physics and optoelectronics applications. Many applications seek to combine a two dimensional (2D) material with another nanomaterial, either another two dimensional material or a zero (0D) or one dimensional (1D) material. The work in this thesis explores the consequences of these interactions from 0D to 2D. We begin in Chapter 2 with a study of energy transfer at 0D-2D interfaces with quantum dots and graphene. In our work we seek to maximize the rate of energy transfer by reducing the distance between the materials. We observe an interplay with the distance-dependence and surface effects from our halogen terminated quantum dots that affect our observed energy transfer. In Chapter 3 we study supercapacitance in composite graphene oxide-carbon nanotube electrodes. At this 2D-1D interface we observe a compounding effect between graphene oxide and carbon nanotubes. Carbon nanotubes increase the accessible surface area of the supercapacitors and improve conductivity by forming a conductive pathway through electrodes. In Chapter 4 we investigate effective means of improving sample quality in TMDCs and discover the importance of the monolayer interface. We observe a drastic improvement in photoluminescence when encapsulating our TMDCs with Boron Nitride. We measure spectral linewidths approaching the intrinsic limit due to this 2D-2D interface. We also effectively reduce excess charge and thus the trion-exciton ratio in our samples through substrate surface passivation. In Chapter 5 we briefly discuss our investigations on chemical doping, heterostructures and interlayer decoupling in ReS2. We observe an increase in intensity for p-doped MoS2 samples. We investigated the charge transfer exciton previously identified in

  3. Novel two-dimensional uranyl-organic assemblages in the citrate and D(-)-citramalate families

    International Nuclear Information System (INIS)

    Thuery, P.

    2008-01-01

    Uranyl nitrate reacts with D(-)-citramalic acid (H(3)citml) under mild hydrothermal conditions to give the two-dimensional polymer [UO 2 (Hcitml)] 1, in which each ligand chelates one metal atom through its hydroxyl and alpha- carboxylate groups and binds to three others in monodentate fashion. The resulting neutral layers display isolated uranyl pentagonal bipyramidal polyhedra. Whereas citric acid (H(4)cit) has been shown previously to give various three- and mono-dimensional uranyl organic assemblages, complexation under hydrothermal conditions in the presence of either NaOH/NEt 4 Cl or pyridine yields the complexes [NEt 4 ] 2 [(UO 2 ) 3 (cit) 2 (H 2 O) 22H 2 O 2 and [Hpy] 2 )[(UO 2 ) 3 (cit)(Hcit)(OH)] 3, respectively, which both crystallize as two- dimensional frameworks. The layers are either planar and separated by the counter ions in 2 or corrugated and hydrogen bonded to one another in 3. In both 2 and 3, [UO 2 (cit)] 2 4- dimeric subunits with edge-sharing pentagonal bipyramidal uranium coordination polyhedra are present but, in both cases and in contrast with previous structures containing [UO 2 (Hcit)] 2 2- dimers, the carboxylate group not involved in the dimer formation is coordinated to another uranyl unit, which is part of either a centrosymmetric hexagonal bipyramidal bis-aquated group or a different, [(UO 2 ) 2 (Hcit)(OH)] dimer. These examples of two- dimensional assemblages further illustrate the variety of architectures which can be obtained with citric and related acids and the important structure-directing effects of the counter ions. (author)

  4. Infinite-dimensional Z2sup(k)-supermanifolds

    International Nuclear Information System (INIS)

    Molotkov, V.

    1984-10-01

    In this paper the theory of finite-dimensional supermanifolds of Berezin, Leites and Kostant is generalized in two directions. First, we introduce infinite-dimensional supermanifolds ''locally isomorphic'' to arbitrary Banach (or, more generally, locally convex) superspaces. This is achieved by considering supermanifolds as functors (equipped with some additional structure) from the category of finite-dimensional Grassman superalgebras into the category of the corresponding smooth manifolds (Banach or locally convex). As examples, flag supermanifolds of Banach superspaces as well as unitary supergroups of Hilbert superspaces are constructed. Second, we define ''generalized'' supermanifolds, graded by Abelian groups Z 2 sup(k), instead of the group Z 2 (Z 2 sup(k)-supermanifolds). The corresponding superfields, describing, potentially, particles with more general statistics than Bose + Fermi, generally speaking, turn out to have an infinite number of components. (author)

  5. Velocity and Dispersion for a Two-Dimensional Random Walk

    International Nuclear Information System (INIS)

    Li Jinghui

    2009-01-01

    In the paper, we consider the transport of a two-dimensional random walk. The velocity and the dispersion of this two-dimensional random walk are derived. It mainly show that: (i) by controlling the values of the transition rates, the direction of the random walk can be reversed; (ii) for some suitably selected transition rates, our two-dimensional random walk can be efficient in comparison with the one-dimensional random walk. Our work is motivated in part by the challenge to explain the unidirectional transport of motor proteins. When the motor proteins move at the turn points of their tracks (i.e., the cytoskeleton filaments and the DNA molecular tubes), some of our results in this paper can be used to deal with the problem. (general)

  6. Graphene and Two-Dimensional Materials for Optoelectronic Applications

    Directory of Open Access Journals (Sweden)

    Andreas Bablich

    2016-03-01

    Full Text Available This article reviews optoelectronic devices based on graphene and related two-dimensional (2D materials. The review includes basic considerations of process technology, including demonstrations of 2D heterostructure growth, and comments on the scalability and manufacturability of the growth methods. We then assess the potential of graphene-based transparent conducting electrodes. A major part of the review describes photodetectors based on lateral graphene p-n junctions and Schottky diodes. Finally, the progress in vertical devices made from 2D/3D heterojunctions, as well as all-2D heterostructures is discussed.

  7. SnSe2 Two Dimensional Anodes for Advanced Sodium Ion Batteries

    KAUST Repository

    Zhang, Fan

    2017-05-30

    Sodium-ion batteries (SIBs) are considered as a promising alternative to lithium-ion batteries (LIBs) for large-scale renewable energy storage units due to the abundance of sodium resource and its low cost. However, the development of anode materials for SIBs to date has been mainly limited to some traditional anodes for LIBs, such as carbonaceous materials. SnSe2 is a member of two dimensional layered transition metal dichalcogenide (TMD) family, which has been predicted to have high theoretical capacity as anode material for sodium ion batteries (756 mAh g-1), thanks to its layered crystal structure. Yet, there have been no studies on using SnSe2 as Na ion battery anode. In this thesis, we developed a simple synthesis method to prepare pure SnSe2 nanosheets, employing N2 saturated NaHSe solution as a new selenium source. The SnSe2 2D sheets achieve theoretical capacity during the first cycle, and a stable and reversible specific capacity of 515 mAh g-1 at 0.1 A g-1 after 100 cycles, with excellent rate performance. Among all of the reported transition metal selenides, our SnSe2 sample has the highest reversible capacity and the best rate performances. A combination of ex-situ high resolution transmission electron microscopy (HRTEM) and X-ray diffraction was used to study the mechanism of sodiation and desodiation process in this SnSe2, and to understand the reason for the excellent results that we have obtained. The analysis indicate that a combination of conversion and alloying reactions take place with SnSe2 anodes during battery operation, which helps to explain the high capacity of SnSe2 anodes for SIBs compared to other binary selenides. Density functional theory was used to elucidate the volume changes taking place in this important 2D material.

  8. New method of three-dimensional reconstruction from two-dimensional MR data sets

    International Nuclear Information System (INIS)

    Wrazidlo, W.; Schneider, S.; Brambs, H.J.; Richter, G.M.; Kauffmann, G.W.; Geiger, B.; Fischer, C.

    1989-01-01

    In medical diagnosis and therapy, cross-sectional images are obtained by means of US, CT, or MR imaging. The authors propose a new solution to the problem of constructing a shape over a set of cross-sectional contours from two-dimensional (2D) MR data sets. The authors' method reduces the problem of constructing a shape over the cross sections to one of constructing a sequence of partial shapes, each of them connecting two cross sections lying on adjacent planes. The solution makes use of the Delaunay triangulation, which is isomorphic in that specific situation. The authors compute this Delaunay triangulation. Shape reconstruction is then achieved section by pruning Delaunay triangulations

  9. The use of virtual reality to reimagine two-dimensional representations of three-dimensional spaces

    Science.gov (United States)

    Fath, Elaine

    2015-03-01

    A familiar realm in the world of two-dimensional art is the craft of taking a flat canvas and creating, through color, size, and perspective, the illusion of a three-dimensional space. Using well-explored tricks of logic and sight, impossible landscapes such as those by surrealists de Chirico or Salvador Dalí seem to be windows into new and incredible spaces which appear to be simultaneously feasible and utterly nonsensical. As real-time 3D imaging becomes increasingly prevalent as an artistic medium, this process takes on an additional layer of depth: no longer is two-dimensional space restricted to strategies of light, color, line and geometry to create the impression of a three-dimensional space. A digital interactive environment is a space laid out in three dimensions, allowing the user to explore impossible environments in a way that feels very real. In this project, surrealist two-dimensional art was researched and reimagined: what would stepping into a de Chirico or a Magritte look and feel like, if the depth and distance created by light and geometry were not simply single-perspective illusions, but fully formed and explorable spaces? 3D environment-building software is allowing us to step into these impossible spaces in ways that 2D representations leave us yearning for. This art project explores what we gain--and what gets left behind--when these impossible spaces become doors, rather than windows. Using sketching, Maya 3D rendering software, and the Unity Engine, surrealist art was reimagined as a fully navigable real-time digital environment. The surrealist movement and its key artists were researched for their use of color, geometry, texture, and space and how these elements contributed to their work as a whole, which often conveys feelings of unexpectedness or uneasiness. The end goal was to preserve these feelings while allowing the viewer to actively engage with the space.

  10. Large gap plasma display cell with auxiliary electrodes: macro-cell experiments and two-dimensional modelling

    International Nuclear Information System (INIS)

    Ouyang, J T; Callegari, Th; Caillier, B; Boeuf, J-P

    2003-01-01

    In this paper we use a two-dimensional fluid model and a 'macroscopic' PDP cell to investigate the possibility of using large gap configurations with auxiliary electrodes to improve the efficiency of PDP discharge cells. The large gap allows operation in a transient positive column regime where energy is more efficiently deposited into xenon excitation, while the auxiliary electrodes are used to keep reasonable values of the operating voltage. Two types of auxiliary electrode configurations (floating and powered) are considered. The discharge characteristics and the discharge efficiency in exciting xenon are studied with simulations and by measuring the intensity of infrared emission from xenon and visible emission from neon in a macroscopic PDP cell. The results show that an efficient positive column regime can be achieved at reasonably low operating voltages when the auxiliary electrode configuration is carefully designed

  11. Crystallization of SHARPIN using an automated two-dimensional grid screen for optimization

    International Nuclear Information System (INIS)

    Stieglitz, Benjamin; Rittinger, Katrin; Haire, Lesley F.

    2012-01-01

    The expression, purification and crystallization of an N-terminal fragment of SHARPIN are reported. Diffraction-quality crystals were obtained using a two-dimensional grid-screen seeding technique. An N-terminal fragment of human SHARPIN was recombinantly expressed in Escherichia coli, purified and crystallized. Crystals suitable for X-ray diffraction were obtained by a one-step optimization of seed dilution and protein concentration using a two-dimensional grid screen. The crystals belonged to the primitive tetragonal space group P4 3 2 1 2, with unit-cell parameters a = b = 61.55, c = 222.81 Å. Complete data sets were collected from native and selenomethionine-substituted protein crystals at 100 K to 2.6 and 2.0 Å resolution, respectively

  12. Two-dimensional versus three-dimensional treatment planning of tangential breast irradiation

    International Nuclear Information System (INIS)

    Damen, E.M.F.; Bruinvis, I.A.D.; Mijnheer, B.J.

    1995-01-01

    Purpose: Full three-dimensional (3-D) treatment planning requires 3-D patient contours and density information, derived either from CT scanning or from other 3-D contouring methods. These contouring techniques are time consuming, and are often not available or cannot be used. Two-dimensional (2-D) treatment planning can be performed using only a few patient contours, made with much simpler techniques, in combination with simulator images for estimating the lung position. In order to investigate the need for full 3-D planning, we compared the performance of both a 2-D and a 3-D planning system in calculating absolute dose values and relative dose distributions in tangential breast irradiation. Methods: Two breast-shaped phantoms were used in this study. The first phantom consists of a polyethylene mould, filled with water and cork to mimic the lung. An ionization chamber can be inserted in the phantom at fixed positions. The second phantom is made of 25 transverse slices of polystyrene and cork, made with a computerized milling machine from CT information. In this phantom, films can be inserted in three sagittal planes. Both phantoms have been irradiated with two tangential 8 MV photon beams. The measured dose distribution has been compared with the dose distribution predicted by the two planning systems. Results: In the central plane, the 3-D planning system predicts the absolute dose with an accuracy of 0.5 - 4%. The dose at the isocentre of the beams agrees within 0.5% with the measured dose. The 2-D system predicts the dose with an accuracy of 0.9 - 3%. The dose calculated at the isocentre is 2.6% higher than the measured dose, because missing lateral scatter is not taken into account in this planning system. In off-axis planes, the calculated absolute dose agrees with the measured dose within 4% for the 2-D system and within 6% for the 3-D system. However, the relative dose distribution is predicted better by the 3-D planning system. Conclusions: This study

  13. Two-dimensional topological photonic systems

    Science.gov (United States)

    Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng

    2017-09-01

    The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.

  14. Two-dimensional atom localization via two standing-wave fields in a four-level atomic system

    International Nuclear Information System (INIS)

    Zhang Hongtao; Wang Hui; Wang Zhiping

    2011-01-01

    We propose a scheme for the two-dimensional (2D) localization of an atom in a four-level Y-type atomic system. By applying two orthogonal standing-wave fields, the atoms can be localized at some special positions, leading to the formation of sub-wavelength 2D periodic spatial distributions. The localization peak position and number as well as the conditional position probability can be controlled by the intensities and detunings of optical fields.

  15. The inaccuracy of conventional one-dimensional parallel thermal resistance circuit model for two-dimensional composite walls

    International Nuclear Information System (INIS)

    Wong, K.-L.; Hsien, T.-L.; Hsiao, M.-C.; Chen, W.-L.; Lin, K.-C.

    2008-01-01

    This investigation is to show that two-dimensional steady state heat transfer problems of composite walls should not be solved by the conventionally one-dimensional parallel thermal resistance circuits (PTRC) model because the interface temperatures are not unique. Thus PTRC model cannot be used like its conventional recognized analogy, parallel electrical resistance circuits (PERC) model which has the unique node electric voltage. Two typical composite wall examples, solved by CFD software, are used to demonstrate the incorrectness. The numerical results are compared with those obtained by PTRC model, and very large differences are observed between their results. This proves that the application of conventional heat transfer PTRC model to two-dimensional composite walls, introduced in most heat transfer text book, is totally incorrect. An alternative one-dimensional separately series thermal resistance circuit (SSTRC) model is proposed and applied to the two-dimensional composite walls with isothermal boundaries. Results with acceptable accuracy can be obtained by the new model

  16. Physicochemical and structural characterization of a two-dimensional polymer performed by using the Langmuir-Blodgett technique

    International Nuclear Information System (INIS)

    Lefevre, Didier

    1995-01-01

    This research thesis addresses the physicochemical and structural characterization of two-dimensional polymer made of polymerizable macro-cycles pre-organised in-plane by using the Langmuir-Blodgett technique. Macro-cycles are porphyrins with four acetylenic functions which bind in both plane directions by formation of diacetylenic covalent bonds. These porphyrins are adsorbed under a single layer of dihexadecyl-phosphoric acid to build up a monomer amphiphilic film. The author reports the characterization of the Langmuir film by the study of compression isotherms and by Brewster angle microscopy. Other techniques are used (UV, visible and infrared spectroscopy, Raman spectroscopy) to highlight the polymerization in LB film. X photo-electronic spectroscopy and secondary ion mass spectroscopy are also used. The author reports the study of the orientation of macro-cycles before and after polymerization by using linear dichroism, electronic paramagnetic resonance and X ray diffraction. The in-plane LB film structure is studied by transmission X ray diffraction, atomic force microscopy in correlation with molecular simulation. The two-dimensional feature of the polymer formed at the water surface is highlighted. The membrane is visualized by electronic and optic microscopy, and characterized by EDXS and electronic diffraction [fr

  17. Bounds on the capacity of constrained two-dimensional codes

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Justesen, Jørn

    2000-01-01

    Bounds on the capacity of constrained two-dimensional (2-D) codes are presented. The bounds of Calkin and Wilf apply to first-order symmetric constraints. The bounds are generalized in a weaker form to higher order and nonsymmetric constraints. Results are given for constraints specified by run-l...

  18. Two loop integrals and QCD scattering

    International Nuclear Information System (INIS)

    Anastasiou, C.

    2001-04-01

    We present the techniques for the calculation of one- and two-loop integrals contributing to the virtual corrections to 22 scattering of massless particles. First, tensor integrals are related to scalar integrals with extra powers of propagators and higher dimension using the Schwinger representation. Integration By Parts and Lorentz Invariance recurrence relations reduce the number of independent scalar integrals to a set of master integrals for which their expansion in ε = 2 - D/2 is calculated using a combination of Feynman parameters, the Negative Dimension Integration Method, the Differential Equations Method, and Mellin-Barnes integral representations. The two-loop matrix-elements for light-quark scattering are calculated in Conventional Dimensional Regularisation by direct evaluation of the Feynman diagrams. The ultraviolet divergences are removed by renormalising with the MS-bar scheme. Finally, the infrared singular behavior is shown to be in agreement with the one anticipated by the application of Catani's formalism for the infrared divergences of generic QCD two-loop amplitudes. (author)

  19. Ultrasensitive near-infrared photodetectors based on graphene-MoTe2-graphene vertical van der Waals heterostructure

    Science.gov (United States)

    Zhang, Kun; Ye, Yu; Dai, Lun; School of Physics, Peking University Team

    Two-dimensional (2D) materials have rapidly established themselves as exceptional building blocks for optoelectronic applications, due to their unique properties and atomically thin nature. Nevertheless, near-infrared (NIR) photodetectors based on layered 2D semiconductors are rarely realized. In this work, we fabricate graphene-MoTe2-graphene vertical vdWs heterostructure by a facile and reliable site controllable transfer method, and apply it for photodetection from visible to the NIR wavelength range. Compared to the 2D semiconductor based photodetectors reported thus far, the graphene-MoTe2-graphene photodetector has superior performance, including high photoresponsivity (110 mA W-1 at 1064 nm and 205 mA W-1 at 473 nm), high external quantum efficiency (EQE, 12.9% at 1064 nm and 53.8% at 473 nm), rapid response and recovery processes (rise time of 24 μs, fall time of 46 μs under 1064 nm illumination), and free from an external source-drain power supply. The all-2D-materials heterostructure has promising applications in future novel high responsivity, high speed and flexible NIR devices.

  20. Three New (2+1)-dimensional Integrable Systems and Some Related Darboux Transformations

    Science.gov (United States)

    Guo, Xiu-Rong

    2016-06-01

    We introduce two operator commutators by using different-degree loop algebras of the Lie algebra A1, then under the framework of zero curvature equations we generate two (2+1)-dimensional integrable hierarchies, including the (2+1)-dimensional shallow water wave (SWW) hierarchy and the (2+1)-dimensional Kaup-Newell (KN) hierarchy. Through reduction of the (2+1)-dimensional hierarchies, we get a (2+1)-dimensional SWW equation and a (2+1)-dimensional KN equation. Furthermore, we obtain two Darboux transformations of the (2+1)-dimensional SWW equation. Similarly, the Darboux transformations of the (2+1)-dimensional KN equation could be deduced. Finally, with the help of the spatial spectral matrix of SWW hierarchy, we generate a (2+1) heat equation and a (2+1) nonlinear generalized SWW system containing inverse operators with respect to the variables x and y by using a reduction spectral problem from the self-dual Yang-Mills equations. Supported by the National Natural Science Foundation of China under Grant No. 11371361, the Shandong Provincial Natural Science Foundation of China under Grant Nos. ZR2012AQ011, ZR2013AL016, ZR2015EM042, National Social Science Foundation of China under Grant No. 13BJY026, the Development of Science and Technology Project under Grant No. 2015NS1048 and A Project of Shandong Province Higher Educational Science and Technology Program under Grant No. J14LI58