349 research outputs found

    JCLAL: A Java framework for active learning

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    Active Learning has become an important area of research owing to the increasing number of real-world problems which contain labelled and unlabelled examples at the same time. JCLAL is a Java Class Library for Active Learning which has an architecture that follows strong principles of object-oriented design. It is easy to use, and it allows the developers to adapt, modify and extend the framework according to their needs. The library offers a variety of active learning methods that have been proposed in the literature. The software is available under the GPL license

    Experimental and numerical analysis of a water emptying pipeline using different air valves

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    The emptying procedure is a common operation that engineers have to face in pipelines. This generates subatmospheric pressure caused by the expansion of air pockets, which can produce the collapse of the system depending on the conditions of the installation. To avoid this problem, engineers have to install air valves in pipelines. However, if air valves are not adequately designed, then the risk in pipelines continues. In this research, a mathematical model is developed to simulate an emptying process in pipelines that can be used for planning this type of operation. The one-dimensional proposed model analyzes the water phase propagation by a new rigid model and the air pockets effect using thermodynamic formulations. The proposed model is validated through measurements of the air pocket absolute pressure, the water velocity and the length of the emptying columns in an experimental facility. Results show that the proposed model can accurately predict the hydraulic characteristic variables. © 2017 by the authors

    Quantitative reconstruction of primary productivity in low latitudes during the last glacial maximum and the mid-to-late Holocene from a global Florisphaera profunda calibration dataset

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    [EN]Ocean net primary productivity (Npp) is a key component of the marine carbon cycle. Multi-model Npp projections based on a few decades of satellite data show large uncertainties, in particular at low latitudes (30°N−30°S). Calibration of sedimentary proxies with satellite-based Npp estimates allows for the quantitative reconstruction of this variable at longer time-scales. Relative abundance of deep-photic zone coccolithophore species Florisphaera profunda in the fossil record can potentially be used as a quantitative proxy for Npp. However, the robustness of this proxy calibration has been tested in very specific oceanographic settings using surface sediment samples. Here, we use a global dataset of surface sediment (n = 1258) and sediment trap (n = 26) samples with relative abundance data of F. profunda (%) to test the robustness of this proxy as a quantitative indicator of Npp. We study the modern and paleo-ecology of this species and the main factors affecting its latitudinal distribution. Results show that F. profunda % is a strong indicator of Npp at latitudes between 30°N and 30°S, while at higher latitudes temperature-related variables are more important. We develop a global calibration model between satellite Npp estimates and F. profunda for the latitudinal range between 30°N and 30°S, and we apply it to several low-latitude sediment cores with available F. profunda counts covering the Late Glacial Maximum (LGM; 24–19 ka) and the Mid-to-Late Holocene period (MLH; <6 ka). Reconstructed Npp during the LGM is 15% higher than during the MLHdue to the intensification of trade winds that enhanced oceanic upwelling at low latitudes

    Rifampin and Triclosan but not Silver is Effective in Preventing Bacterial Infection of Vascular Dacron Graft Material

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    AbstractObjectives. To evaluate the efficacy of silver- or Triclosan-coated prosthetic material compared to Rifampin bonded Dacron concerning their resistance to infection following subcutaneous implantation and contamination with Staphylococcus aureus.Design. Animal experimental study in mice.Material and methods. Thirty-six C3H/HcN mice (Charles River Lab., Sulzfeld, Germany) with a weight between 24 and 27 g were randomised into six groups counting six animals each. Group I: control, gel-sealed dacron graft, group II: gel-sealed dacron graft and local contamination, group III: Intergard®-Silver-prosthesis and contamination, group IV: silver/gel-sealed dacron prosthesis (test graft) and contamination, group V: Rifampin-bonded gel-sealed graft and contamination, group VI: Triclosan/collagen-coated dacron graft and contamination. Dacron graft material 0.8×1 cm was subcutaneously implanted in mice. Local contamination with 2×107/0.2 ml S. aureus ATCC 25923 was carried out in groups II to VI. On day 14 the animals were killed and the grafts were explanted. The microscopic, histologic and microbiological evaluation of the graft material and the perigraft tissue was performed.Results. In control group I no case of infection was detected. In group II, 6 of 6 animals showed infection. In group III (Intergard®-Silver) and group IV (silver/gel-test graft) were 6 of 6, in group V (Rifampin) only 1 of 6 grafts and in group VI (Triclosan) 4 of 6 grafts were infected. The difference between the low rate of infection in group V (Rifampin) in comparison to the completely infected groups III and IV (Silver) as well as the control group II was significant. Treatment of grafts with Triclosan could prevent infection only in 1/3 of the cases in group IV.Conclusion. Silver coating failed to prevent graft infection material. A potential antimicrobial property was evident for Triclosan whereas Rifampin-bonded grafts exhibit a significantly reduced infection rate. Thus, silver-coated vascular grafts cannot ensure protection from vascular graft infection

    Subsurface Flows in and Around Active Regions with Rotating and Non-rotating Sunspots

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    The temporal variation of the horizontal velocity in subsurface layers beneath three different types of active regions is studied using the technique of ring diagrams. In this study, we select active regions (ARs) 10923, 10930, 10935 from three consecutive Carrington rotations: AR 10930 contains a fast-rotating sunspot in a strong emerging active region while other two have non-rotating sunspots with emerging flux in AR 10923 and decaying flux in AR 10935. The depth range covered is from the surface to about 12 Mm. In order to minimize the influence of systematic effects, the selection of active and quiet regions is made so that these were observed at the same heliographic locations on the solar disk. We find a significant variation in both components of the horizontal velocity in active regions as compared to quiet regions. The magnitude is higher in emerging-flux regions than in the decaying-flux region, in agreement with earlier findings. Further, we clearly see a significant temporal variation in depth profiles of both zonal and meridional flow components in AR 10930, with the variation in the zonal component being more pronounced. We also notice a significant influence of the plasma motion in areas closest to the rotating sunspot in AR 10930 while areas surrounding the non-rotating sunspots in all three cases are least affected by the presence of the active region in their neighborhood.Comment: Solar Physics (in press), includes 11 figure

    Vibrational properties of CdGa2S4 at high pressure

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    [EN] Raman scattering measurements have been performed in cadmium digallium sulphide (CdGa2S4) with defect chalcopyrite structure up to 25 GPa in order to study its pressure-induced phase transitions. These measurements have been complemented and compared with latticedynamics ab initio calculations including the TO-LO splitting at high pressures in order to provide a better assignment of experimental Raman modes. In addition, experimental and theoretical Gruneisen parameters have been reported in order to calculate the molar heat capacity and thermal expansion coefficient of CdGa2S4. Our measurements provide evidence that CdGa2S4 undergoes an irreversible phase transition above 15 GPa to a Raman-inactive phase, likely with a disordered rock salt structure. Moreover, the Raman spectrum observed on downstroke from 25 GPa to 2 GPa has been attributed to a new phase, tentatively identified as a disordered zinc blende structure, that undergoes a reversible phase transition to the Raman-inactive phase above 10 GPa. Published under license by AIP Publishing.The authors thank the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) under Grant Nos. MAT2016-75586-C4-2/3-P and MAT2015-71070-REDC (MALTA Consolider) and the Generalitat Valenciana under Project No. PROMETEO/2018/123-EFIMAT. E. P.-G., A. M., and P. R.-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster.Gallego-Parra, S.; Gomis, O.; Vilaplana Cerda, RI.; Ortiz, H.; Perez-Gonzalez, E.; Luna Molina, R.; Rodríguez-Hernández, P.... (2019). Vibrational properties of CdGa2S4 at high pressure. Journal of Applied Physics. 125(11):1-12. https://doi.org/10.1063/1.5080503S11212511Gomis, O., Santamaría-Pérez, D., Vilaplana, R., Luna, R., Sans, J. A., Manjón, F. J., … Ursaki, V. V. (2014). Structural and elastic properties of defect chalcopyrite HgGa2S4 under high pressure. Journal of Alloys and Compounds, 583, 70-78. doi:10.1016/j.jallcom.2013.08.123Cohen, M. L. (1985). Calculation of bulk moduli of diamond and zinc-blende solids. Physical Review B, 32(12), 7988-7991. doi:10.1103/physrevb.32.7988Kim, J. W., & Kim, Y. J. (2007). Optical Properties of Eu Doped M-Ga2S4 (M:Zn, Ca, Sr) Phosphors for White Light Emitting Diodes. Journal of Nanoscience and Nanotechnology, 7(11), 4065-4068. doi:10.1166/jnn.2007.066Yu, R., Noh, H. M., Moon, B. K., Choi, B. C., Jeong, J. H., Jang, K., … Jang, J. K. (2013). Photoluminescence properties of a new red-emitting Mn-activated ZnGa2S4 phosphor. Materials Research Bulletin, 48(6), 2154-2158. doi:10.1016/j.materresbull.2013.02.017Liang, F., Kang, L., Lin, Z., Wu, Y., & Chen, C. (2017). Analysis and prediction of mid-IR nonlinear optical metal sulfides with diamond-like structures. Coordination Chemistry Reviews, 333, 57-70. doi:10.1016/j.ccr.2016.11.012Sahariya, J., Kumar, P., & Soni, A. (2017). Structural and optical investigations of ZnGa2X4 (X = S, Se) compounds for solar photovoltaic applications. Materials Chemistry and Physics, 199, 257-264. doi:10.1016/j.matchemphys.2017.07.003Syrbu, N. N., Tiron, A. V., Parvan, V. I., Zalamai, V. V., & Tiginyanu, I. M. (2015). Interference of birefractive waves in CdGa2S4 crystals. Physica B: Condensed Matter, 463, 88-92. doi:10.1016/j.physb.2015.02.007Vilaplana, R., Gomis, O., Manjón, F. J., Ortiz, H. M., Pérez-González, E., López-Solano, J., … Tiginyanu, I. M. (2013). Lattice Dynamics Study of HgGa2Se4at High Pressures. The Journal of Physical Chemistry C, 117(30), 15773-15781. doi:10.1021/jp402493rGrzechnik, A., Ursaki, V. V., Syassen, K., Loa, I., Tiginyanu, I. M., & Hanfland, M. (2001). Pressure-Induced Phase Transitions in Cadmium Thiogallate CdGa2Se4. Journal of Solid State Chemistry, 160(1), 205-211. doi:10.1006/jssc.2001.9224Gomis, O., Vilaplana, R., Manjón, F. J., Ruiz-Fuertes, J., Pérez-González, E., López-Solano, J., … Tiginyanu, I. M. (2015). HgGa2 Se4 under high pressure: An optical absorption study. physica status solidi (b), 252(9), 2043-2051. doi:10.1002/pssb.201451714Rahnamaye Aliabad, H. A., Basirat, S., & Ahmad, I. (2017). Structural, electronical and thermoelectric properties of CdGa2S4 compound under high pressures by mBJ approach. Journal of Materials Science: Materials in Electronics, 28(21), 16476-16483. doi:10.1007/s10854-017-7559-1Ursaki, V. V., Burlakov, I. I., Tiginyanu, I. M., Raptis, Y. S., Anastassakis, E., & Anedda, A. (1999). 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A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Sans, J. Á., Santamaría-Pérez, D., Popescu, C., Gomis, O., Manjón, F. J., Vilaplana, R., … Tiginyanu, I. M. (2014). Structural and Vibrational Properties of CdAl2S4under High Pressure: Experimental and Theoretical Approach. The Journal of Physical Chemistry C, 118(28), 15363-15374. doi:10.1021/jp5037926Lottici, P. P., & Razzetti, C. (1984). Raman scattering in mixed defect chalcopyrite crystals. Journal of Molecular Structure, 115, 133-136. doi:10.1016/0022-2860(84)80032-0Kerimova, T. G., Abdullaev, N. A., Mamedova, I. A., Badalova, Z. I., Guliev, R. A., Paucar, R., … Mamedov, N. T. (2013). Optical phonons in CdGa2S4x Se4(1 − x) alloys. Semiconductors, 47(6), 761-766. doi:10.1134/s1063782613060110Tiginyanu, I. M., Lottici, P. P., Razzetti, C., & Gennari, S. (1993). Effects of the Cations on the Raman Spectra of Sulphur Defect Chalcopyrites. Japanese Journal of Applied Physics, 32(S3), 561. doi:10.7567/jjaps.32s3.561Kerimova, T. G., Mamedova, I. A., Abdullayev, N. A., Asadullayeva, S. Q., & Badalova, Z. I. (2014). Raman scattering in ZnGa2Se4 single crystals. Semiconductors, 48(7), 868-871. doi:10.1134/s1063782614070112Razzetti, C., & Lottici, P. P. (1993). Raman Scattering in Defective AIIB2IIIX4VICompounds and Alloys. Japanese Journal of Applied Physics, 32(S3), 431. doi:10.7567/jjaps.32s3.431Syrbu, N. N., Nemerenco, L. L., & Cojocaru, O. (2002). Vibrational and Polariton Spectra of CdGa2S4 and CdAl2S4 Crystals. Crystal Research and Technology, 37(1), 101-110. doi:10.1002/1521-4079(200202)37:13.0.co;2-dGomis, O., Vilaplana, R., Manjón, F. J., Santamaría-Pérez, D., Errandonea, D., Pérez-González, E., … Ursaki, V. V. (2013). High-pressure study of the structural and elastic properties of defect-chalcopyrite HgGa2Se4. Journal of Applied Physics, 113(7), 073510. doi:10.1063/1.4792495Gomis, O., Ortiz, H. M., Sans, J. A., Manjón, F. J., Santamaría-Pérez, D., Rodríguez-Hernández, P., & Muñoz, A. (2016). InBO3 and ScBO3 at high pressures: An ab initio study of elastic and thermodynamic properties. Journal of Physics and Chemistry of Solids, 98, 198-208. doi:10.1016/j.jpcs.2016.07.002K. R. Allakhverdiev, Frontiers of High Pressure Research II: Application of High Pressure to Low-Dimensional Novel Electronic Materials (Springer, 2001), p. 99.Lottici, P. P., & Razzetti, C. (1983). A comparison of the raman spectra of ZnGa2Se4 and other gallium defect chalcopyrites. Solid State Communications, 46(9), 681-684. doi:10.1016/0038-1098(83)90506-9Sanjuán, M. L., & Morón, M. C. (2002). Raman study of Zn1−xMnxGa2Se4 diluted magnetic semiconductors: disorder and resonance effects. Physica B: Condensed Matter, 316-317, 565-567. doi:10.1016/s0921-4526(02)00574-4Radautsan, S. I., Tiginyanu, I. M., Ursakii, V. V., Fomin, V. M., & Pokatilov, E. P. (1990). The Peculiarities of the Temperature Broadening of Raman Light Scattering Lines in Zn(Cd)Ga2Se4 Single Crystals. physica status solidi (b), 162(1), K63-K66. doi:10.1002/pssb.2221620143Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835Manjón, F. J., Gomis, O., Vilaplana, R., Sans, J. A., & Ortiz, H. M. (2013). Order-disorder processes in adamantine ternary ordered-vacancy compounds. physica status solidi (b), 250(8), 1496-1504. doi:10.1002/pssb.201248596Mitani, T., Naitou, T., Matsuishi, K., Onari, S., Allakhverdiev, K., Gashimzade, F., & Kerimova, T. (2003). Raman scattering in CdGa2Se4 under pressure. physica status solidi (b), 235(2), 321-325. doi:10.1002/pssb.200301579Meenakshi, S., Vijyakumar, V., Godwal, B. K., Eifler, A., Orgzall, I., Tkachev, S., & Hochheimer, H. D. (2006). High pressure X-ray diffraction study of CdAl2Se4 and Raman study of AAl2Se4 (A=Hg, Zn) and CdAl2X4 (X=Se, S). Journal of Physics and Chemistry of Solids, 67(8), 1660-1667. doi:10.1016/j.jpcs.2006.02.015Manjón, F. J., Marí, B., Serrano, J., & Romero, A. H. (2005). Silent Raman modes in zinc oxide and related nitrides. Journal of Applied Physics, 97(5), 053516. doi:10.1063/1.1856222H. Bilz and W. Kress, Phonon Dispersion Relations in Insulators (Springer, 1979), p. 110.Cheng, Y. C., Jin, C. Q., Gao, F., Wu, X. L., Zhong, W., Li, S. H., & Chu, P. K. (2009). Raman scattering study of zinc blende and wurtzite ZnS. Journal of Applied Physics, 106(12), 123505. doi:10.1063/1.3270401(2017). Theoretical Analysis of Elastic, Mechanical and Phonon Properties of Wurtzite Zinc Sulfide under Pressure. Crystals, 7(6), 161. doi:10.3390/cryst7060161González, J., Fernández, B. J., Besson, J. M., Gauthier, M., & Polian, A. (1992). High-pressure behavior of Raman modes inCuGaS2. Physical Review B, 46(23), 15092-15101. doi:10.1103/physrevb.46.15092Talwar, D. N., Vandevyver, M., Kunc, K., & Zigone, M. (1981). Lattice dynamics of zinc chalcogenides under compression: Phonon dispersion, mode Grüneisen, and thermal expansion. Physical Review B, 24(2), 741-753. doi:10.1103/physrevb.24.741Griesinger, A., Spindler, K., & Hahne, E. (1999). Measurements and theoretical modelling of the effective thermal conductivity of zeolites. International Journal of Heat and Mass Transfer, 42(23), 4363-4374. doi:10.1016/s0017-9310(99)00096-4Hofmeister, A. M., & Mao, H. -k. (2002). Redefinition of the mode Gruneisen parameter for polyatomic substances and thermodynamic implications. Proceedings of the National Academy of Sciences, 99(2), 559-564. doi:10.1073/pnas.241631698Miller, S. A., Gorai, P., Ortiz, B. R., Goyal, A., Gao, D., Barnett, S. A., … Toberer, E. S. (2017). Capturing Anharmonicity in a Lattice Thermal Conductivity Model for High-Throughput Predictions. Chemistry of Materials, 29(6), 2494-2501. doi:10.1021/acs.chemmater.6b04179Zeier, W. G., Zevalkink, A., Gibbs, Z. M., Hautier, G., Kanatzidis, M. G., & Snyder, G. J. (2016). Thinking Like a Chemist: Intuition in Thermoelectric Materials. Angewandte Chemie International Edition, 55(24), 6826-6841. doi:10.1002/anie.201508381Barron, T. H. . (1957). Grüneisen parameters for the equation of state of solids. Annals of Physics, 1(1), 77-90. doi:10.1016/0003-4916(57)90006-4Arora, A. K. (1990). Grüneisen parameter of soft phonons and high pressure phase transitions in semiconductors. Journal of Physics and Chemistry of Solids, 51(4), 373-375. doi:10.1016/0022-3697(90)90122-vGrüneisen, E. (1912). Theorie des festen Zustandes einatomiger Elemente. Annalen der Physik, 344(12), 257-306. doi:10.1002/andp.19123441202Mishra, K. K., Bevara, S., Ravindran, T. R., Patwe, S. J., Gupta, M. K., Mittal, R., … Tyagi, A. K. (2018). High pressure behavior of complex phosphate K2Ce[PO4]2: Grüneisen parameter and anharmonicity properties. Journal of Solid State Chemistry, 258, 845-853. doi:10.1016/j.jssc.2017.12.022Manjon, F. J., Tiginyanu, I., & Ursaki, V. (Eds.). (2014). Pressure-Induced Phase Transitions in AB2X4 Chalcogenide Compounds. Springer Series in Materials Science. doi:10.1007/978-3-642-40367-5Allakhverdiev, K., Gashimzade, F., Kerimova, T., Mitani, T., Naitou, T., Matsuishi, K., & Onari, S. (2003). Raman scattering under pressure in ZnGa2Se4. Journal of Physics and Chemistry of Solids, 64(9-10), 1597-1601. doi:10.1016/s0022-3697(03)00077-5Parlak, C., & Eryiğit, R. (2006). Ab initiovolume-dependent elastic and lattice dynamical properties of chalcopyriteCuGaSe2. Physical Review B, 73(24). doi:10.1103/physrevb.73.245217Kern, G., Kresse, G., & Hafner, J. (1999). Ab initiocalculation of the lattice dynamics and phase diagram of boron nitride. Physical Review B, 59(13), 8551-8559. doi:10.1103/physrevb.59.8551B. A. Weinstein and R. Zallen, Light Scattering in Solids IV (Springer, 1984), p. 463.Schwer, H., & Krämer, V. (1990). The crystal structures of CdAl2S4, HgAl2S4, and HgGa2S4. Zeitschrift für Kristallographie, 190(1-2), 103-110. doi:10.1524/zkri.1990.190.1-2.103Mamedov, K. K., Aliev, M. M., Kerimov, I. G., & Kh. Nani, R. (1972). Heat capacity of AIIB2IIIC4VI-type ternary semiconducting compounds at low temperatures. Physica Status Solidi (a), 9(2), K149-K152. doi:10.1002/pssa.2210090255Quintero, M., Morocoima, M., Guerrero, E., & Ruiz, J. (1994). Temperature variation of lattice parameters and thermal expansion coefficients of the compound MnGa2Se4. Physica Status Solidi (a), 146(2), 587-593. doi:10.1002/pssa.2211460203Ravindran, T. R., Arora, A. K., & Mary, T. A. (2000). High Pressure Behavior ofZrW2O8: Grüneisen Parameter and Thermal Properties. 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    Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra

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    With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atmospheric parameters (T_(eff), log g, ξ, and [Fe/H]) by means of the STEPAR code, a PYTHON implementation of the equivalent width method that employs the 2017 version of the MOOG code and a grid of MARCS model atmospheres. We compiled four Fe I and Fe II line lists suited to metal-rich dwarfs, metal-poor dwarfs, metal-rich giants, and metal-poor giants that cover the wavelength range from 5300 to 17 100 Å, thus substantially increasing the number of identified Fe I and Fe II lines up to 653 and 23, respectively, We examined the impact of the near-infrared Fe and Fen lines upon our parameter determinations after an exhaustive literature search, placing special emphasis on the 14 Gala benchmark stars contained in our sample, Even though our parameter determinations remain in good agreement with the literature values, the increase in the number of Fe l and Fe II lines when the near-infrared region is taken into account reveals a deeper T_(eff) scale that might stem from a higher sensitivity of the near-infrared lines to T_(eff)

    Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2

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    The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization, Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of the magnetic moments of 14 deg. from their general antiferromagnetic alignment, one of the largest reported to date. This results in weak ferromagnetism with a ferromagnetic component of 1 mu_B. The large canting is due to the interplay between the antiferromagnetic exchange interaction and the local single-ion anisotropy in the chiral lattice. The magnetically ordered structure of (pyrimidine)2FeCl2, however, is not chiral. The implications of these findings for the search of molecule based materials exhibiting chiral magnetic ordering is discussed.Comment: 6 pages, 5 figure
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