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3. AIMH research activities 2022

Author

Aloia N., Amato G., Bartalesi V., Benedetti F., Bolettieri P., Cafarelli D., Carrara F., Casarosa V., Ciampi L., Coccomini D. A., Concordia C., Corbara S., Di Benedetto M., Esuli A., Falchi F., Gennaro C., Lagani G., Lenzi E., Meghini C., Messina N., Metilli D., Molinari A., Moreo A., Nardi A., Pedrotti A., Pratelli N., Rabitti F., Savino P., Sebastiani F., Sperduti G., Thanos C., Trupiano L., Vadicamo L., and Vairo C.

Subjects
Machine Learning, Similarity Search, Deep Learning, Artificial Intelligence, Computer Vision, Representation Learning, Transfer Learning, Text Classification, Multimedia Information Retrieval
Abstract

The Artificial Intelligence for Media and Humanities laboratory (AIMH) has the mission to investigate and advance the state of the art in the Artificial Intelligence field, specifically addressing applications to digital media and digital humanities, and taking also into account issues related to scalability. This report summarize the 2022 activities of the research group.

Published
2022

6. Methods of Comparative Study

Author

Armstrong, W., Hodgson, J. G., Booth, R. E., Gaitens, P., Grime, J. P., Band, S. R., Mowforth, M. A., Crawford, R. M. M., Bossard, C. C., Hillier, S. H., Leprince, O., Thorpe, P. C., Duran, M. V., Reiling, K., Davison, A. W., Ashenden, T. W., Pearcy, R. W., Hendry, G. A. F., Howarth, C. J., Willis, A. J., Pearce, A. M. K., Farrar, J. F., Campbell, B. D., Mackey, J. M. L., Hunt, R., Neal, A. M., Laffarga, J., Montserrat-Marti, G., Stockey, A., Whitehouse, J., Hand, D. W., Hannah, M. A., Neal, A., Poorter, H., Welschen, R. A. M., Anderson, J. M., Scholes, J. D., Horton, P., MacPherson-Stewart, S. F., Dearman, R. S., Cooper, J. E. L., Tasker, D. E., Welker, J. M., Stewart, G. R., Walker, D. A., Leegood, R. C., Lambers, H., van der Werf, A., Bergkotte, M., Thompson, K., Reader, R. J., Jalili, A., Spencer, R. E., Matthews, N., Leake, J. R., Read, D. J., Fitter, A. H., Brocklebank, K. J., Price, A. H., Earnshaw, M. J., Merzlyak, M. N., Rorison, I. H., Gupta, P. L., Etherington, J. R., Thanos, C. A., Baker, A. J. M., Snowden, R. E. D., Wheeler, B. D., Sellars, B., Warman, E. A., Hendry, G. A. F., editor, and Grime, J. P., editor

Published
1993
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10. Unenhanced computed tomography as a diagnostic tool in suspected pulmonary hypertension: a retrospective cross-sectional pilot study [version 2; peer review: 2 approved]

Author

Charlie Elliot, Krit Dwivedi, Dheyaa Alkanfar, Michael Sharkey, Catherine Hill, Thanos Charalampololous, Robin Condliffe, Smitha Rajaram, Andrew J. Swift, David G. Kiely, Christopher S. Johns, Ze Ming Goh, Samual Barnes, and Tarik Julius

Subjects
Computed tomography, Pulmonary hypertension, Diagnosis, Right Ventricle, eng, Medicine, Science
Abstract

Background Computed tomography pulmonary angiography (CTPA) has been proposed to be diagnostic for pulmonary hypertension (PH) in multiple studies. However, the utility of the unenhanced CT measurements diagnosing PH has not been fully assessed. This study aimed to assess the diagnostic utility and reproducibility of cardiac and great vessel parameters on unenhanced computed tomography (CT) in suspected pulmonary hypertension (PH). Methods In total, 42 patients with suspected PH who underwent unenhanced CT thorax and right heart catheterization (RHC) were included in the study. Three observers (a consultant radiologist, a specialist registrar in radiology, and a medical student) measured the parameters by using unenhanced CT. Diagnostic accuracy of the parameters was assessed by area under the receiver operating characteristic curve (AUC). Inter-observer variability between the consultant radiologist (primary observer) and the two secondary observers was determined by intra-class correlation analysis (ICC). Results Overall, 35 patients were diagnosed with PH by RHC while 7 patients were not. Main pulmonary arterial (MPA) diameter was the strongest (AUC 0.79 to 0.87) and the most reproducible great vessel parameter. ICC comparing the MPA diameter measurement of the consultant radiologist to the specialist registrar’s and the medical student’s were 0.96 and 0.92, respectively. Right atrial area was the cardiac measurement with highest accuracy and reproducibility (AUC 0.76 to 0.79; ICC 0.980, 0.950) followed by tricuspid annulus diameter (AUC 0.76 to 0.79; ICC 0.790, 0.800). Conclusions MPA diameter and right atrial areas showed high reproducibility. Diagnostic accuracies of these were within the range of acceptable to excellent, and might have clinical value. Tricuspid annular diameter was less reliable and less diagnostic and was therefore not a recommended diagnostic measurement.

Published
2024
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13. Beneficial effects of intermediate dosage of anticoagulation treatment on the prognosis of hospitalized COVID-19 patients: The ETHRA study

Author

Poulakou, G. Dimakakos, E. Kollias, A. Kyriakoulis, K.G. Rapti, V. Trontzas, I. Thanos, C. Abdelrasoul, M. Vantana, T. Leontis, K. Kakalou, E. Argyraki, K. Baraboutis, I. Michelakis, E. Giamarellos-Bourboulis, E. Dimakou, K. Tsoukalas, G. Rapti, A. Michelakis, E.D. Syrigos, K.N.

Abstract

Background/Aim: To investigate the efficacy (prognosis, coagulation/inflammation biomarkers) and safety (bleeding events) of different anticoagulation dosages in COVID-19 inpatients. Patients and Methods: COVID-19 inpatients (Athens, Greece) were included. The "Enhanced dose THRomboprophylaxis in Admissions (ETHRA)" protocol was applied in certain Departments, suggesting the use of intermediate anticoagulation dosage. The primary endpoint was a composite of intubation/venous thromboembolism/death. Inflammation/coagulation parameters were assessed. Results: Among 127 admissions, 95 fulfilled the inclusion criteria. Twenty-one events (4 deaths, 17 intubations) were observed. Regression analysis demonstrated significant reduction of events with intermediate or therapeutic dosage [HR=0.16 (95%CI=0.05-0.52) p=0.002; HR=0.17 (0.04-0.71) p=0.015, respectively]. D-Dimer values were higher in those who met the composite endpoint. Intermediate dosage treatment was associated with decreased values of ferritin. Three patients (3%) had minor hemorrhagic complications. Conclusion: Anticoagulation treatment (particularly intermediate dosage) appears to have positive impact on COVID-19 inpatients' prognosis by inhibiting both coagulation and inflammatory cascades. © 2021 International Institute of Anticancer Research. All rights reserved.

Published
2021

14. AIMH research activities 2021

Author

Aloia N., Amato G., Bartalesi V., Benedetti F., Bolettieri P., Cafarelli D., Carrara F., Casarosa V., Coccomini D., Ciampi L., Concordia C., Corbara S., Di Benedetto M., Esuli A., Falchi F., Gennaro C., Lagani G., Massoli F. V., Meghini C., Messina N., Metilli D., Molinari A., Moreo A., Nardi A., Pedrotti A., Pratelli N., Rabitti F., Savino P., Sebastiani F., Sperduti G., Thanos C., Trupiano L., Vadicamo L., and Vairo C.

Subjects
Multimedia information retrieval, Artificial Intelligence, Similarity search, Natural language processing, Computer vision, Digital humanities
Abstract

The Artificial Intelligence for Media and Humanities laboratory (AIMH) has the mission to investigate and advance the state of the art in the Artificial Intelligence field, specifically addressing applications to digital media and digital humanities, and taking also into account issues related to scalability. This report summarize the 2021 activities of the research group.

Published
2021

15. Free behind bars: Effects of browsing exclusion on the growth and regeneration of Zelkova abelicea

Author

Fazan, L. Ghosn, D. Remoundou, I. Gotsiou, P. Thanos, C. Pasta, S. Garfì, G. Kozlowski, G.

Abstract

Caprine overbrowsing is a main threat to trees of pastoral mountain woodlands in the Mediterranean region of Europe. In this study, we assess the impact of browsing exclusion on the growth and regeneration of the endangered Zelkova abelicea, a Paleogene relict tree endemic to Crete (Greece). Shoot elongation, height growth and natural regeneration were monitored during two to five years in 31 fenced plots across the distribution range of the species. We found that in the absence of browsing pressure, Z. abelicea produces shoots on average two times longer than when browsed, therefore clearly demonstrating the negative impact of current browsing pressure on the growth performance of the species. Shoot elongation and height growth were maximal in most plots during the first two years following fencing, after which growth rates decreased. The proportion of trees that reached a height considered out of reach of caprine browsing had more than doubled already after four years, although this was dependent on initial tree height. Shoot elongation and height growth were positively correlated with tree height, and smaller trees took more time to reach a specific height. Seedlings were only found in three fenced plots as well as in two control browsed areas during a single year and only in western Crete. This underlines the possible strong and concerning impact of climatic factors on seed formation as well as on seedling growth and survival, although site specificities such as stand structure and micro-topography should also be considered. Our findings have important implications for conservation actions, as they can help choose which stands and which individuals to fence in priority for efficient long-term conservation. © 2021 The Authors

Published
2021

18. Session 17 Ecophysiology

Author

Aktan, N., Palavan-Ünsal, N., Andonov, A. V., Georgieva, K. M., Yordanov, I. T., Atanasiu, L., Petcu, E., Atkin, O. K., Barabás, N. K., Erdei, L., Baumann, J., Bader, K. P., Bayçu, G., Önal, M., Bock, C., Jacob, A., Mayer, A., Kirst, G. O., Borovsky, G., Voronova, L., Voinikov, V., Borowski, E., Kozlowska, L., Botos-Bálo, B., Váradi, Gy., Happ, I., Busuioc, V. M., Toma, S. I., Cabeza, C. E., Ledent, J. F., Chamont, S., Christov, C., Boshcova, M., Furnadzieva, S., Zafirova, T., Čiamporová, M., Banásová, V., Ouzounidou, G., Clement, Han, Van Hasselt, Philip R., De Gara, L., De Tullio, M. C., Paciolla, C., Stefani, A., Arrigoni, O., de Ramon, M., Reigosa, M. J., Doussi, M. A., Thanos, C. A., Fenik, S. I., Trofimyak, T. B., Blume, Ya. B., Fernandez-Pascual, M., De Lorenzo, C., De Felipe, M. R., Minchin, F. R., Gordon, A. J., Filonick, L. A., Frechilla, S., Royuela, M., Arrese-Igor, C., Aparicio-Tejo, P. M., Gabbrielli, R., Gremigni, P., Pandolfini, T., Gloser, J., Gloser, V., Goncharova, N. V., Sheverdov, V. V., Zhebrakova, I. V., Grakhov, V. P., Kozeko, V. G., Greger, M., Heyman, E., Grishko, V. N., Guglielminetti, L., Perata, P., Alpi, A., Gutterman, Yitzchak, Honour, S. J., Ihle, C., Laasch, H., Ivanova, T. I., Yudina, O. S., Kacperska, A., Kadis, C. C., Georghiou, K., Khilko, T. D., Klimov, S. V., Trunova, T. I., Kosakivska, L. V., Maidebura, E. V., Kostyuk, O. P., Mikheev, A. N., Kutlakhmedov, Yu. A., Kozlova, J. I., Reutsky, V. G., Kravetz, A. P., Pavlenco, Y. A., Kubacka, M., Kacperska, A., Kühn, F., Kuznetsov, Vladimir V., Landberg, T., Greger, M., Campos, P. S., Matos, M. C., Laureano, J. A., Ramalho, J. R., Guedes, M. E., Lidon, F. C., Laureano, J. A., Campos, P. S., Ramalho, J. R., Lidon, F. C., Guedes, M. E., Matos, M. C., Leina, G. D., Lopez-Carbonell, M., Prinsen, E., Pastor, A., Van Onckelen, H., Lösch, R., Zohlen, A., Gonzales, A., Jimenez, M. S., Morales, D., Aschan, G., Lütz, C., Kaiser, F., Masarovičová, E., Lux, A., Kobelová, G., Mattioni, C., Gabbrielli, R., Negru, P. V., Medvedeva, T. N., Tudorake, G. F., Newbery, R. M., Olah, R., Masarovičová, E., Ouzounidou, G., Čiamporová, M., Moustakas, M., Karataglis, S., Pedrol, N., Ramos, P., Reigosa, M. J., Peisker, M., Tichá, I., Václavík, J., Ostareck, D., Pfeffer, M., Peisker, M., Pons, T. L., Popović, M., Kevrešan, S., Kandrač, J., Kočiš, J., Štajner, D., Petrivić, N., Kastori, R., Popovicheva, L. A., Shevchenko, Y. B., Porankiewicz, J., Gwóźdź, E. A., Prokhnevsky, A. I., Ruchko, M. V., Sorochinsky, B. V., Sergeeva, A. Y., Kostyuk, O. P., Mikheev, A. N., Przymusiński, R., Rucińska, R., Gwóźdź, E. A., Pugnaire, F. I., Haase, P., Incoll, L. D., Clark, S. C., Pukacki, P. M., Radotić, K., Todorović, S., Zakrzewska, J., Jeremić, M., Ramos, P., Pedrol, N., Reigosa, M. J., Ruchko, M. V., Sorochinsky, B. V., Sakač, Z., Panković, D., Ćupina, T., Plesničar, M., Save, R., Biel, C., Pons, J., Massons, J., Scheuerlein, R., Treml, S., Thar, B., Tirlapur, U. K., Häder, D. -P., Schneider, J., Legocka, J., Winiarska, G., Schreiber, L., Shabala, S. N., Sheremetiev, S. N., Shtemenko, N. I., Sosak-Swiderska, B., Tyrawska, D., Mazurek, U., Stevanović, B., Šinžar, J., Glišić, O., Stroinski, A., Terbea, Maria, Micut, Gh., Titei, V., Thanos, C. A., Thibaud, M. C., Betsche, T., Tosserams, M., Visser, A. J., Groen, M. W., Kalis, G., Kwant, R., Magendans, E., Rozema, J., Tyrawska, D., Bajan, C., Popowska-Nowak, E., Grochala, K., Utrillas, M. J., Alegre, L., Van Den Boogaard, H. A. G. M., Alewijnse, D., Veneklaas, E. J., Lambers, H., Van Der Kooij, T. A. W., De Kok, L. J., Van Der Werf, Adrie, Bouma, Tjeerd, Scheurwater, Ingeborg, Lambers, Hans, Van Hasselt, P. R., Chow, W. S., Anderson, J. M., Vidal, D., Grau, D., Sanjose, M., Fleck, I., Villar, R., Merino, J., Vincze, G. Y., Vallner, J., Balazsy, S., Balogh, A., Kiss, F., Zaric, L. J., Stefanovic, L., Kerecki, B., Radosavljevic, M., Zivalyuk, O. B., and Filonick, I. A.

Published
1994
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19. AIMH research activities 2020

Author

Aloia N., Amato G., Bartalesi V., Benedetti F., Bolettieri P., Carrara F., Casarosa V., Ciampi L., Concordia C., Corbara S., Esuli A., Falchi F., Gennaro C., Lagani G., Massoli F. V., Meghini C., Messina N., Metilli D., Molinari A., Moreo A., Nardi A., Pedrotti A., Pratelli N., Rabitti F., Savino P., Sebastiani F., Thanos C., Trupiano L., Vadicamo L., and Vairo C.

Subjects
Artificial intelligence, Multimedia information retrieval, Similarity search, Natural language processing, Computer vision, Digital humanities
Abstract

Annual Report of the Artificial Intelligence for Media and Humanities laboratory (AIMH) research activities in 2020.

Published
2020

28. Population characteristics of Juniperus drupacea (Cupressaceae) at the westernmost marginal area of its world distribution (Mt. Parnon, Greece).

Author

Daskalakou, E. N., Oikonomidis, S., Boutsios, S., Ioannidis, K., and Thanos, C. A.

Subjects
CUPRESSACEAE, JUNIPERS, FOREST density, CLIMATE change, SPECIES, HABITATS
Abstract

Juniperus drupacea Labill. is a relict, dioecious tree/shrub found in Turkey, Syria, Lebanon and Israel, while in Europe it is native only in Greece (on Mt. Parnon and in a restricted area of Mt. Taygetos). According to the IUCN Red List criteria, J. drupacea has been assessed as endangered (EN) for Europe, with major threats being grazing of saplings, overexploitation of its wood and climate change. For the first time to our knowledge, the structure of the diverse stands of J. drupacea across its entire population range on Mt. Parnon is being studied. Thirteen monitoring plots (20 × 25 m) have been selected and established to cover fully both the species' geographic distribution on Mt. Parnon as well as the heterogeneity of its habitats. The morphometric traits (gender, canopy height, canopy base height, diameter at breast height and number of trunks) for each individual within the plots were recorded during the monitoring periods of 2020 and 2021. The Female / Male individual ratios, in both the northern and the southern area of the species' range deviate significantly from the expected ratio 1:1 of the evolutionary stable strategy, it should be noted that from the 729 individuals recorded 254 were juveniles. Canopy height may reach 11.5 m with a DBH up to 132 cm whereas individuals are usually multi-trunked (1-9 trunks were recorded). The average tree density was 1121.5 ± 139.8 individuals per hectare for the entire mountainous population range. [ABSTRACT FROM AUTHOR]

Published
2022
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29. Session 08 Germination and dormancy

Author

Antipova, O. V., Obroucheva, N. V., Appenroth, K. -J., OelmÜller, R., Babenko, L. M., Nesterova, An., Musatenko, L. I., Berestetsky, V. A., Bogatek, R., Capocchi, A., Fontanlni, D., Galleschi, L., Grilli, I., Small, J. G. Chris, Kemp, K., Costa, J., Ricardo, C. P. Pinto, Dawidowicz-Grzegorzewska, A., Delipetrou, P., Georghiou, K., Thanos, C. A., Elpidina, E. N., Karssen, C. M., Hilhorst, H. W. M., Kavakli, I. H., Allakhverdiev, S. R., Kaya, Z., Kazmierczak, A., Knypl, J. S., Kepczyński, J., Corbineau, F., Come, D., Kepczyńska, E., Kontos, F., Spyropoulos, C. G., Korableva, N. P., Platonova, T. A., Dogonadze, M. Z., Lewak, S., Martin-Closas, L. L., Baquedano, J. M., Armengol, M. A., Pelacho, A. M., Nesterova, A. N., Musatenko, L. I., Yakovchenko, E. V., Pavón, M. M., Darder, M., De Paula, M., Torres, M., Martínez-Honduvilla, C. J., Martín, M. A., Pérez, M., De Paula, M., Darder, M., Torres, M., Frutos, G., Martínez-Honduvilla, C. J., Pérez-Cerezo, M. A., Torres, M., Vega, A., Serrano, J., Podgieter, G. P., Small, J. G. Chris, Pozdova, L. M., Balmasowa, M. A., Ranjan, R., Roth-Bejerano, N., Sarlach, R. S., Rai, V. K., Sytnik, K. M., Generalova, V. N., Martyn, G. I., Musatenko, L. I., Vedenicheva, N. P., Tommasi, F., Paciolla, C., Tullio, M. C. De, Arrigoni, O., Vedenicheva, N. P., Generalova, V. N., Yatsuhashi, H., and Scheuerlein, R.

Published
1994
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41. Multos: a document server for distributed office systems

Author

Bertino, E., Rabitti, F., Thanos, C., Goos, G., editor, Hartmanis, J., editor, Barstow, D., editor, Brauer, W., editor, Brinch Hansen, P., editor, Gries, D., editor, Luckham, D., editor, Moler, C., editor, Pnueli, A., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Schmidt, J. W., editor, Ceri, S., editor, and Missikoff, M., editor

Published
1988
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43. RDA Europe - Planning and activities report

Author

Thanos C. and Zoppi F.

Subjects
Technology, Computer Science
Abstract

This WP4 Planning and Activities Report describes the actions that are intended within WP4 in the coming 12 months to engage with the practitioners and to organize uptake. It is the second report of this type describing what has been done and what is being planned.

Published
2016

44. RDA Europe - Planning and activities report 3

Author

Thanos C. and Zoppi F.

Subjects
Technology, Computer Science
Abstract

This WP4 Planning and Activities Report describes the actions that are intended within WP4 in the coming 12 months to engage with the practitioners and to organize uptake. It is the second report of this type describing what has been done and what is being planned.

Published
2016

45. Seed germination traits of Pinus heldreichii in two Greek populations and implications for conservation

Author

Daskalakou EN, Koutsovoulou K, Oikonomidis S, and Thanos CA

Subjects
Climate Change, Cold Stratification, Cotyledon Number, Heldreich’s Pine, Light Response, Seed Ecophysiology, Forestry, SD1-669.5
Abstract

Seed germination traits were assessed on Pinus heldreichii H. Christ, a Tertiary relict, high-elevation Mediterranean pine, endemic in the western Balkan Peninsula and southern Italy; it is naturally grown at the northern Greece mountains, but also found in shrubby form above the timberline. Closed and mature cones were collected (October) for three consecutive years from Pindos Range and Mt. Olympus populations. Cone and seed morphological traits were recorded along with the seedling cotyledon number. Seed germination tests were performed under various ecologically meaningful temperatures and light regimes; climate change effects on seed germination and seedling development were assessed based on two climate scenarios. Final seed germination was moderate (~55%) on both, untreated seed lots at most favourable conditions (15 and 20 °C). Although cold stratification is not an absolute requirement, seed germination rate and final percentage are promoted by both a month of cold stratification (at least 30 or 45 days) and white light. The predicted climate change suggests that a prolonged drought period (>3 months) might turn out by the end of the century in the populations studied. Although the temperature increase might not have significant effects in the germination window of the species. The rainfall decrease will inevitably expose the young seedlings to the summer drought, thus increasing the potential mortality rate. Both ex situ (e.g., germplasm conservation) and in situ measures of conservation are recommended for the species survival in Greece, with a particular focus on the populations established at lower altitudes.

Published
2022
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47. RDA Europe - Planning and activities report 1

Author

Thanos C. and Castelli D.

Subjects
Technology, Digital Libraries, Computer Science
Abstract

This WP4 Planning and Activities Report describes the actions that are intended within WP4 in the coming 12 months to engage with the practitioners and to organize uptake. It is the first report of this type and an update will be written before the end of this first 12 month period.

Published
2015

48. Scientific Data Reusability: Concepts, Impediments and Enabling Technologies

Author

Thanos C.

Subjects
Digital Libraries, Data reusability, Data publication process
Abstract

High-­throughput scientific instruments are generating massive amounts of data. Today one of the main challenges faced by researchers is to make the best use of the world's growing wealth of data. Data (re)usability is becoming a distinct characteristic of modern scientific practice, as it allows reanalysis of evidence, reproduction and verification of results, minimizing duplication of effort, and building on the work of others. The paper addresses the technological dimension of data reusability: the scientific data universe, the impediments of data (re)reuse; the data publication process as a bridge between data author and user and the relevant technologies enabling this process.

Published
2015

49. Dielectric relaxation of α-cyclodextrin-polyiodide complexes (α-cyclodextrin)2 · BaI2 · I2 · 8H2O and (α-cyclodextrin)2 · KI3 · I2 · 8H2O

Author

John C. Papaioannou and Thanos C. Ghikas

Subjects
chemistry.chemical_classification, Cyclodextrin, Chemistry, Hydrogen bond, Relaxation (NMR), Biophysics, Dielectric, Condensed Matter Physics, Polyiodide, chemistry.chemical_compound, Crystallography, Computational chemistry, Molecule, Partial transformation, Crystallite, Physical and Theoretical Chemistry, Molecular Biology
Abstract

The frequency and temperature dependence of the real (∊′) and imaginary (∊″) parts of the dielectric constant of the polycrystalline complexes (α-CD)2 · Bal2 · I2 · 8H2O and (α-CD)2 · KI3 · I2 · 8H2O (α-CD = α-cyclodetrin) have been investigated over the frequency and temperature ranges 0–100 kHz and 120–300 K, respectively. The temperature dependences of ∊′, ∊″ and the phase shift φ show two steps, two peaks and two minima, respectively, revealing the existence of two kinds of water molecule, the tightly bound and the easily movable water molecules, in both complexes. The first peak of (T) or the first minimum of φ(T) presents the transformation of flip-flop hydrogen bonds to the normal state. The second ∊″ (T) peak or φ(T) minimum corresponds to the easily movable water molecules or to a partial transformation of tightly bound to easily movable water molecules. For T > 270K both samples show semiconductive behaviour with energy gaps of 1.84eV for the (α-CD)2 · BaI2 · I2 · 8H2O complex and 1.36eV for the...

Published
2003

50. Dielectric relaxation of α-cyclodextrin—polyiodide complexes (α-cyclodextrin)2· LiI3· I2· 8H2O and (α-cyclodextrin)2· Cd0.5· I5· 26H2O

Author

Thanos C. Ghikas and John C. Papaioannou

Subjects
chemistry.chemical_classification, Materials science, Cyclodextrin, Relaxation (NMR), Biophysics, Dielectric, Condensed Matter Physics, symbols.namesake, Crystallography, Polyiodide, chemistry.chemical_compound, chemistry, symbols, Molecule, Crystallite, Physical and Theoretical Chemistry, Dispersion (chemistry), Molecular Biology, Debye
Abstract

The frequency and temperature dependence of real (∊′) and imaginary (∊″) parts of the dielectric constant of polycrystalline complexes (α-CD)2 · LiI3 · I2 · 8H2O and (α-CD)2 · Cd0.5 · I5 · 26H2O (α-CD = α-cyclodextrin) has been investigated over the frequency and temperature ranges of 0–100 kHz and 12–300 K. The dielectric behaviour is described well by Debye type relaxation (α-dispersion). Both systems exhibit an additional Ω dispersion at low frequencies which is attributed to ionic conductance and is much greater in the case of Li due to the greater mobility of cations Li+. The temperature dependence of ∊′ reveals the existence of two kinds of water molecule in the case of the (α-CD)2 · Cd0.5 · I5 · 26H2O complex; these can be classified as tiqhtly bound and easily movable water molecules that cause two steps in ∊′ versus T plots. In the case of the (α-CD)2 · LiI3 · I2 · 8H2O complex the water molecules are tightly bound and as a result only one step is observed in these graphs. These finding are also ...

Published
2002

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