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190 results on '"D., Vlassopoulos"'

1. Underlying mechanism of shear-banding in soft glasses of charged colloidal rods with orientational domains

Author

D. Parisi, D. Vlassopoulos, H. Kriegs, J. K. G. Dhont, and K. Kang

Subjects
Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Mechanics of Materials, Mechanical Engineering, ddc:530, General Materials Science, Condensed Matter Physics
Abstract

Soft glasses of colloidal rods ( fd-virus particles) with orientational domains were recently shown to exhibit inhomogeneous flow profiles [Dhont et al., Phys. Rev. Fluids 2, 043301 (2017)]: fracture and accompanied plug flow at small shear rates, which transits to gradient shear-banding on increasing the shear rate, while a uniform flow profile develops at sufficiently high shear rates. These flow profiles coexist with Taylor-vorticity bands. The texture of such glasses under flow conditions consists of domains with varying orientations. The observed gradient shear-banding was solely attributed to the strong shear thinning behavior of the material inside the domains (henceforth abbreviated as domain-interior), without considering the texture stress that is due to interactions between the glassy domains. Here, we present new experiments on the shear-banding transition to assess the role played by the texture stress in comparison to the domain-interior stress. For a large concentration, well into the glassy state, it is found that both texture stress and domain-interior stress contribute significantly to the gradient shear-banding transition in the shear-rate region where it occurs. On the other hand, for a small concentration close to the glass-transition concentration, the domains are shown to coalesce within the shear-rate range where gradient shear-banding is observed. As a result, the texture stress diminishes and the domain-interior stress increases upon coalescence, leading to a stress plateau. Thus, a subtle interplay exists between the stresses arising from the structural order on two widely separated length scales from interactions between domains and from the rod-rod interactions within the domain-interior for both concentrations.

Published
2022
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2. Parallel Memory Accessing for FFT Architectures

Author

Kitsakis, V. Nakos, K. Reisis, D. Vlassopoulos, N.

Subjects
Hardware_ARITHMETICANDLOGICSTRUCTURES
Abstract

The current paper introduces an efficient technique for parallel data addressing in FFT architectures performing in-place computations. The novel addressing organization provides parallel load and store of the data involved in radix-r butterfly computations and leads to an efficient architecture when r is a power of 2. The addressing scheme is based on a permutation of the FFT data, which leads to the improvement of the address generating circuit and the butterfly processor control. Moreover, the proposed technique is suitable for mixed radix applications, especially for radixes that are powers of 2 and straightforward continuous flow implementation. The paper presents the technique and the resulting FFT architecture and shows the advantages of the architecture compared to hitherto published results. The implementations on a Xilinx FPGA Virtex-7 VC707 of the in-place radix-8 FFT architectures with input sizes 64 and 512 complex points validate the results. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

Published
2018

3. ACID BASE, ION DISORDERS, LITHISASIS

Author

M. A. El-Shahawy, H. S. Rasmussen, P. T. Lavin, A. Yang, D. K. Packham, B. Singh, S. D. Roger, M. Fusaro, L. Dalle Carbonare, A. Dusso, M. V. Arcidiacono, S. Pasho, M. Gallieni, M. S. Ormanji, F. Korkes, R. Meca, L. C. Baia, R. R. Ferraz, I. P. Heilberg, I. Nistor, I. Bararu, M.-C. Apavaloaie, L. Voroneanu, M.-D. Donciu, E. V. Nagler, A. Covic, H.-W. Gil, S.-H. Park, S.-Y. Hong, B. Ponte, H. Alwan, M. Pruijm, D. Ackermann, I. Guessous, G. Ehret, F. Paccaud, M. Mohaupt, A. Pechere-Bertschi, M. Burnier, P.-Y. Martin, M. Bochud, V. Filiopoulos, D. Biblaki, N. Manolios, I. Karatzas, D. Arvanitis, D. Vlassopoulos, A. Altuntas, V. Kidir, S. Inal, S. Diker, N. Cil, H. Orhan, M. T. Sezer, M. Verdelho, N. Rodrigues, F. Ribeiro, W. Y. Qunibi, H. Azar, R. Ossman, M. Flamant, D. Chelala, P. Ria, A. Fabris, C. Branco, G. Gambaro, A. Lupo, J. Hao, L. Qiu, Y. Li, R. Li, X. Li, L. Chen, S. Verdesca, D. Cucchiari, M. Podesta, S. Badalamenti, N. M. H. Veldhuijzen, K. G. F. Gerritsen, W. H. Boer, A. C. Abrahams, F. Mangione, P. Albrizio, V. Sepe, P. Esposito, A. Manini, S. Muciaccia, and A. Dal Canton

Subjects
Transplantation, medicine.medical_specialty, Hyperkalemia, business.industry, Placebo, medicine.disease, Gastroenterology, Tolerability, Nephrology, Diabetes mellitus, Heart failure, Internal medicine, medicine, Risk factor, medicine.symptom, Adverse effect, business, Kidney disease
Abstract

Introduction and Aims: Hyperkalaemia is a risk factor for mortality in patients with cardiovascular disease and chronic kidney disease (CKD) (Goyal, 2012; Torlen, 2012) and limits use of renin-angiotensin-aldosterone system inhibitors (RAASi) in these patients. Sodium (or calcium) polystyrene sulfonate (SPS/CPS) has uncertain efficacy and has been associated with substantial adverse events, as well as poor gastrointestinal tolerability, and hence is suboptimal for acute use and unsuitable for chronic use (Harel, 2013; Sterns, 2010). Therefore, there is a need for a hyperkalaemia treatment that rapidly reduces serum potassium (K+) and is safe and well tolerated in these patients. ZS-9, a nonabsorbed cation exchanger designed to specifically entrap excess K +, significantly reduced K+ vs placebo over 48 hr with excellent tolerability in patients with CKD (Ash, 2013). We report acute-phase efficacy in a Phase 3 trial of ZS-9 in patients with hyperkalemia. Methods: Patients (N=753) with serum K+ 5.0-6.5 mmol/L were randomised (1:1:1:1:1) to ZS-9 (1.25g, 2.5g, 5g or 10g) or placebo given three times daily (TID) with meals for 48 hr (acute phase), after which those with K+ ≤4.9 mmol/L (n=542) were re-randomised to ZS-9 or placebo once daily for Day 3-15. Serum K+ was measured at baseline and at predefined intervals, including 1, 4, 24, and 48 hr after the first dose. The acute-phase primary efficacy endpoint was the rate of K+ change over the first 48 hr, using longitudinal modeling to account for all post-baseline data. Results:Mean K+ at baseline was 5.3 mmol/L. Substantial percentages of patients had CKD (60%), a history of heart failure (40%), or diabetes (60%) or were on RAASi therapy (67%). ZS-9 demonstrated significant dose-dependent reductions in K+; the acute-phase primary efficacy endpoint was met for ZS-9 2.5g (p=0.0009), 5g (p

Published
2014
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4. DIALYSIS. PATHOPHYSIOLOGY AND CLINICAL STUDIES

Author

J. K. Humalda, S. Assa, G. J. Navis, C. F. M. Franssen, M. H. De Borst, H. Ogawa, Y. Ota, T. Watanabe, Y. Watanabe, H. Nishii, A. Sato, J. Waniewski, M. Debowska, A. Wojcik-Zaluska, A. Ksiazek, W. Zaluska, C. M. Guastoni, C. Turri, L. Toma, G. Rombola, G. Frattini, G. Romei Longhena, U. Teatini, D.-C. Siriopol, S. Stuard, A. Ciolan, G. Mircescu, D. Raluca, I. Nistor, A. Covic, C. L. De Roij Van Zuijdewijn, I. Chapdelaine, M. J. Nube, P. J. Blankestijn, M. L. Bots, S. J. Konings, M. A. Van Den Dorpel, N. C. Van Der Weerd, P. M. Ter Wee, M. P. Grooteman, P. S. Djuric, A. Jankovic, J. Tosic, S. Bajcetic, T. Damjanovic, J. Popovic, N. Dimkovic, J. Marinkovic, Z. Djuric, V. Knezevic, T. Lazarevic, S. Ljubenovic, R. Markovic, V. Rabrenovic, L. Djukanovic, V. Radovic Maslarevic, V. Mathrani, P. Drew, J. I. Chess, A. I. Williams, S. Robertson, M. Jibani, V. I. Aithal, M. Kumwenda, G. Roberts, A. I. Mikhail, A. E. Grzegorzewska, G. Ostromecki, A. Mostowska, A. Sowi ska, P. P. Jagodzi ski, H.-Y. Wu, H.-Y. Chen, S.-P. Hsu, M.-F. Pai, J.-Y. Yang, Y.-S. Peng, M. Hirose, T. Hasegawa, N. Kaneshima, F. Sasai, D. Komukai, K. Takahashi, F. Koiwa, K. Shishido, A. Yoshimura, G. Selim, O. Stojceva-Taneva, L. Tozija, P. Dzekova-Vidimliski, L. Trajceska, Z. Petronievic, S. Gelev, V. Amitov, A. Sikole, S. J. Moon, S. Y. Yoon, D. H. Shin, J. E. Lee, H.-J. Kim, H.-C. Park, D. Hadjiyannakos, V. Filiopoulos, G. Loukas, S. Pagonis, C. Andriopoulos, A. Drakou, D. Vlassopoulos, C. Catarino, P. Cunha, S. Ribeiro, P. Rocha-Pereira, F. Reis, M. Sameiro-Faria, V. Miranda, E. Bronze-Rocha, L. Belo, E. Costa, A. Santos-Silva, A. De Mauri, M. Brambilla, D. Chiarinotti, D. Lizio, R. Matheoud, N. Conti, M. M. Conte, A. Carriero, M. De Leo, A. V. Karpetas, P. A. Sarafidis, P. I. Georgianos, G. Koutroumpas, D. Divanis, P. Vakianis, G. Tzanis, K. Raptopoulou, A. Protogerou, D. Stamatiadis, C. Syrganis, V. Liakopoulos, G. Efstratiadis, A. N. Lasaridis, M. Tersi, D. N. Stamatiadis, P. Kuczera, M. Adamczak, A. Wiecek, S. Bove, B. Giacon, R. Corradini, E. Prati, M. Brognoli, A. Tommasi, L. Sereni, G. Palladino, H. Moriya, Y. Mochida, K. Ishioka, M. Oka, K. Maesato, S. Hidaka, T. Ohtake, S. Kobayashi, A. Moura, J. Madureira, P. Alija, J. C. Fernandes, J. G. Oliveira, M. Lopez, M. Filgueiras, L. Amado, M. Vieira, J.-H. Seok, H. Y. Choi, S. K. Ha, H. C. Park, M. Bossola, A. Laudisio, M. Antocicco, L. Tazza, G. Colloca, M. Tosato, G. Zuccala, E. M. Ettema, J. Kuipers, H. Groen, R. T. Gansevoort, K. Stade, S. J. L. Bakker, C. A. J. M. Gaillard, R. Westerhuis, J. Bacchetta, K. Couchoud, S. Semlali, A.-L. Sellier-Leclerc, A. Bertholet-Thomas, R. Cartier, P. Cochat, B. Ranchin, J. C. Kim, K. Park, C. Van Ende, D. Wilmes, F. E. Lecouvet, L. Labriola, R. Cuvelier, G. Van Ingelgem, M. Jadoul, C. Doriana, P. David, F. Capurro, M. Brustia, C. E. Ruva, S. Giungi, E. Di Stasio, S. Lemesch, B. Leber, A. Horvath, W. Ribitsch, G. Schilcher, G. Zettel, M. Tawdrous, A. R. Rosenkranz, V. Stadlbauer-Kollner, H. Matsushima, A. Oyama, E. Bosch Benitez-Parodi, E. Baamonde Laborda, F. Batista Garcia, G. Perez Suarez, G. Anton Perez, C. Garcia Canton, A. Toledo Gonzalez, M. M. Lago Alonso, M. D. Checa Andres, G. Cobo, C. Di Gioia, R. Camacho, C. Garcia Lacalle, O. Ortega, I. Rodriguez, J. Herrero, A. Oliet, M. Ortiz, C. Mon, A. Vigil, P. Gallar, V. Pellu, P. E. Nebiolo, K. Sasaki, S. Yamguchi, A. Hesaka, E. Iwahashi, S. Sakai, T. Fujimoto, S. Minami, Y. Fujita, K. Yokoyama, E. Shutov, G. Ryabinskya, S. Lashutin, E. Gorelova, E. Volodicheva, M. A. Podesta, G. Cancarini, D. Cucchiari, A. Montanelli, S. Badalamenti, G. Graziani, E. Distasio, I. Pchelin, A. Shishkin, Y. Fedorova, C.-C. Kao, T.-S. Chu, T.-J. Tsai, K.-D. Wu, M.-S. Wu, V. Raikou, P. Kaisidis, E. Tsamparlis, P. Kanellopoulos, J. Boletis, A. Ueda, A. Hirayama, S. Owada, K. Nagai, C. Saito, and K. Yamagata

Subjects
03 medical and health sciences, Transplantation, medicine.medical_specialty, 0302 clinical medicine, Nephrology, business.industry, 030232 urology & nephrology, medicine, 030204 cardiovascular system & hematology, Intensive care medicine, Dialysis (biochemistry), business, Pathophysiology
Published
2014
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5. CKD-MBD II

Author

T. Fujii, S. Suzuki, M. Shinozaki, H. Tanaka, S. Bell, S. Cooper, C. Lomonte, P. Libutti, D. Chimienti, F. Casucci, A. Bruno, M. Antonelli, P. Lisi, L. Cocola, C. Basile, A. Negri, E. Del Valle, M. Zanchetta, J. Zanchetta, M. C. Di Vico, M. Ferraresi, A. Pia, E. Aroasio, S. Gonella, E. Mongilardi, R. Clari, I. Moro, G. B. Piccoli, E. Gonzalez-Parra, L. Rodriguez-Osorio, A. Ortiz-Arduan, C. de la Piedra, J. Egido, M. V. Perez Gomez, A. A. Tabikh, B. Afsar, A. Kirkpantur, Y. Imanishi, M. Yamagata, Y. Nagata, M. Ohara, T. Michigami, T. Yukimura, M. Inaba, B. Bieber, B. Robinson, L. Mariani, S. Jacobson, L. Frimat, J. Bommer, R. Pisoni, F. Tentori, P. Ciceri, F. Elli, D. Brancaccio, M. Cozzolino, M. Adamczak, A. Wiecek, P. Kuczera, S. Sezer, Z. Bal, E. Tutal, O. Kal, D. Yavuz, I. Y ld r m, B. Sayin, R. Ozelsancak, S. Ozkurt, S. Turk, N. Ozdemir, R. Lehmann, M. Roesel, P. Fritz, N. Braun, C. Ulmer, W. Steurer, B. Dagmar, G. Ott, J. Dippon, D. Alscher, M. Kimmel, J. Latus, A. Turkvatan, M. Balci, S. Mandiroglu, B. Seloglu, M. Alkis, M. Serin, Y. Calik, S. Erkula, H. Gorboz, F. Mandiroglu, E. Lindley, M. Cruz Casal, S. Rogers, J. Pancirova, J. Kernc, J. B. Copley, D. Fouque, I. Kiss, Z. Kiss, A. Szabo, J. Szegedi, J. Balla, E. Ladanyi, B. Csiky, O. orkossy, M. Torok, S. Turi, C. Ambrus, G. Deak, A. Tisler, I. Kulcsar, V. K d r, A. Altuntas, A. Akp nar, H. Orhan, M. Sezer, V. Filiopoulos, N. Manolios, D. Arvanitis, I. Pani, K. Panagiotopoulos, D. Vlassopoulos, M. E. Rodriguez-Ortiz, A. Canalejo, C. Herencia, J. M. Martinez-Moreno, A. Peralta-Ramirez, P. Perez-Martinez, J. F. Navarro-Gonzalez, M. Rodriguez, M. Peter, K. Gundlach, S. Steppan, J. Passlick-Deetjen, J. R. Munoz-Castaneda, Y. Almaden, M. Rodriguez-Ortiz, J. Martinez-Moreno, I. Lopez, E. Aguilera-Tejero, N. Hanafusa, I. Masakane, S. Ito, S. Nakai, K. Maeda, H. Suzuki, M. Tsunoda, R. Ikee, N. Sasaki, M. Sato, N. Hashimoto, M.-H. Wang, K.-Y. Hung, C.-K. Chiang, J.-W. Huang, K.-C. Lu, C.-L. Lang, K. Okano, T. Yamashita, Y. Tsuruta, A. Hibi, N. Miwa, N. Kimata, K. Tsuchiya, K. Nitta, T. Akiba, L. Harb, H. Komaba, T. Kakuta, T. Suga, M. Fukagawa, H. Kikuchi, H. Shimada, R. Karasawa, M. Suzuki, M. Zhelyazkova-Savova, D. Gerova, D. Paskalev, V. Ikonomov, R. Zortcheva, B. Galunska, G. Jean, P. Deleaval, J.-M. Hurot, C. Lorriaux, B. Mayor, C. Chazot, H. Vannucchi, M. T. Vannucchi, J. C. Martins, J. L. Merino, J. L. Teruel, M. Fernandez-Lucas, J. J. Villafruela, B. Bueno, A. Gomis, V. Paraiso, C. Quereda, F. H. Ibrahim, N. Z. Fadhlina, E. K. Ng, K. M. Thong, B. L. Goh, D. M. Sulaiman, D. A. N. Fatimah, D. O. Evi, S. R. Siti, R. J. Wilson, M. Keith, B. Gros, A. Galan, J. A. Herrero, I. Oyaguez, M. A. Casado, S. Lucisano, G. Coppolino, A. Villari, V. Cernaro, R. Lupica, D. Trimboli, C. Aloisi, and M. Buemi

Subjects
Oncology, Transplantation, medicine.medical_specialty, Nephrology, business.industry, Internal medicine, medicine, business
Published
2013
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6. Pathophysiology and clinical studies in CKD 1-5

Author

A. Gerakis, A. Halapas, M. Chrissoheris, I. Giatras, R. Andritsou, I. Nikolaou, N. Bouboulis, E. Pattakos, K. Spargias, R. Kalaitzidis, D. Karasavvidou, K. Pappas, G. Katatsis, A. Tatsioni, K. Siamopoulos, M. H. de Borst, R. Hajhosseiny, H. Tamez, J. Wenger, R. Thadhani, D. J. Goldsmith, L. Zanoli, S. Rastelli, C. Marcantoni, J. Blanco, C. Tamburino, P. Castellino, T. Larsen, J. Jensen, J. Bech, E. Pedersen, F. Mose, D. Leckstrom, T. Bhuvanakrishna, A. McGrath, D. Goldsmith, K. Muras, A. Masajtis-Zagajewska, M. Nowicki, H. C. Rayner, J. Baharani, S. Smith, V. Suresh, I. Dasgupta, F. Zarzoulas, O. Balafa, L. Di Lullo, F. Floccari, R. Rivera, A. Gorini, M. Malaguti, V. Barbera, A. Granata, A. Santoboni, M. Luczak, D. Formanowicz, E. Pawliczak, M. Wanic-Kossowska, L. Koziol, M. Figlerowicz, J. Bommer, M. Fliser, P. Roth, D. Saure, S. Vettoretti, C. Alfieri, R. Floreani, A. Regalia, C. Bonanomi, R. Meazza, F. Magrini, P. Messa, V. Jankowski, W. Zidek, J. Joachim, K. Lee, I. H. Hwang, S. B. Lee, D. W. Lee, I. Y. Kim, I. S. Kwak, E. Y. Seong, M. J. Shin, H. Rhee, B. Y. Yang, P. Dattolo, S. Michelassi, S. Sisca, M. Allinovi, M. Amidone, A. Mehmetaj, F. Pizzarelli, V. Filiopoulos, N. Manolios, D. Hadjiyannakos, D. Arvanitis, K. Panagiotopoulos, D. Vlassopoulos, J. S. Kim, B. G. Han, S. O. Choi, J. W. Yang, S. Shojai, A. Babu, P. Boddana, D. Dipankar, R. Alvarado, G. Garcia-Pino, E. Ruiz-Donoso, E. Chavez, E. Luna, F. Caravaca, H. Geiger, S. Buttner, L.-L. Lv, Y. Cao, M. Zheng, B.-C. Liu, G. N. Kouvelos, V. D. Raikou, E. M. Arnaoutoglou, H. J. Milionis, J. N. Boletis, M. I. Matsagkas, I. Raiola, F. Trepiccione, M. Pluvio, R. Raiola, G. Capasso, I. Kaykov, L. Kukoleva, R. Zverkov, A. Smirnov, S. Hammami, A. Frih, S. Hajem, M. Hammami, and L. Wan

Subjects
Transplantation, medicine.medical_specialty, Nephrology, business.industry, medicine, Intensive care medicine, business, Pathophysiology
Published
2013
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7. CKD-MBD - A

Author

S. Stracke, M. Sonntagbauer, C. Aymanns, T. Dabers, G. Cammerer, D. Henne-Bruns, P. Wurl, F. Keller, J. Floege, A. Covic, M. Ketteler, A. Rastogi, E. Chong, L. Lisk, S. Sprague, S. Gaillard, M. Lopfe, M. Wilhelm, F. Funk, V. Kalia, S. Willsie, P. Winkle, G. A. Block, M. S. Persky, B. M. Shamblin, M. F. Baltazar, M. C. Comelli, Y.-A. Lu, Y.-C. Liu, S.-Y. Lee, H.-H. Hsu, Y.-C. Chen, C.-C. Yu, C.-C. Hung, C.-W. Yang, V. Dixit, L. Cheng, J. Zhang, E. Tonkin, R. Jaladi, P. Obalapur, S. Dodda, W. Shrivastava, S. Dama, S. Kesana, D. Fry, W. Rubas, D. Martin, J. Riggs, S. Kantak, S. Harrison, S. Doberstein, L. Tartaglione, M. Pasquali, C. Leonangeli, G. Mandanici, M. L. Muci, S. Rotondi, S. Silas, S. Mazzaferro, M. Fusaro, M. Noale, G. Tripepi, A. Piccoli, A. Naso, S. Giannini, D. Miozzo, C. Venturelli, A. Pica, G. Brunori, R. Cristofaro, M. Gallieni, J.-h. Shin, S. H. Kim, S.-H. Yu, J. Martins, J. H. Castro, B. Vogt, R. Oliveira, V. Jorgetti, J. T. Caramori, P. Scully, D. O'Flaherty, A. Sankaralingam, G. Hampson, D. Goldsmith, D. Hadjiyannakos, G. Milatos, V. Filiopoulos, M. Sonikian, I. Karatzas, D. Vlassopoulos, A. Ullah, K. Abdulnabi, P. Gallagher, A. Khalil, J. Alexander, V. Mishra, P. Pai, G. W. Kang, K. S. Ahn, and I. H. Lee

Subjects
Oncology, Transplantation, medicine.medical_specialty, Nephrology, business.industry, Internal medicine, medicine, business
Published
2013
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8. AKI - Clinical

Author

E. Gok Oguz, R. Olmaz, K. Turgutalp, N. Muslu, M. A. Sungur, A. Kiykim, W. Van Biesen, J. Vanmassenhove, G. Glorieux, R. Vanholder, S. Chew, K. Forster, T. Kaufeld, J. Kielstein, T. Schilling, A. Haverich, H. Haller, B. Schmidt, P. Hu, X. Liang, Y. Chen, R. LI, F. Jiang, Z. LI, W. Shi, C. C. W. Lim, C. M. L. Chia, A. K. Tan, C. S. Tan, R. Ng, S. Subramani, A. Perez de Jose, C. Bernis Carro, R. Madero Jarabo, J. Bustamante, J. A. Sanchez Tomero, W. Chung, H. Ro, J. H. Chang, H. H. Lee, J. Y. Jung, L. Fazzari, A. Giuliani, J. Scrivano, L. Pettorini, U. Benedetto, R. Luciani, A. Roscitano, A. Napoletano, D. Coclite, E. Cordova, G. Punzo, R. Sinatra, P. Mene, N. Pirozzi, L. Shavit, R. Manilov, N. Algur, Y. Wiener-Well, I. Slotki, C. Pipili, C. S. Vrettou, K. Avrami, F. Economidou, K. Glynos, S. Ioannidou, V. Markaki, E. Douka, S. Nanas, A. De Pascalis, P. Cofano, S. Proia, A. Valletta, O. Vitale, F. Russo, E. Buongiorno, V. Filiopoulos, D. Biblaki, D. Lazarou, D. Chrysis, M. Fatourou, S. Lafoyianni, D. Vlassopoulos, O. Zakiyanov, V. Kriha, J. Vachek, J. Svarcova, T. Zima, V. Tesar, M. Kalousova, M. Kaushik, C. Ronco, D. Cruz, L. Zhang, W. Zhang, N. Chen, A. A. Ejaz, G. Kambhampati, N. Ejaz, B. Dass, V. Lapsia, A. A. Arif, A. Asmar, M. Shimada, M. Alsabbagh, R. Aiyer, R. Johnson, T.-H. Chen, C.-H. Chang, M.-Y. Chang, Y.-C. Tian, C.-C. Hung, J.-T. Fang, C.-W. Yang, Y.-C. Chen, V. Cantaluppi, A. D. Quercia, F. Figliolini, S. Giacalone, A. Pacitti, M. Gai, C. Guarena, G. Leonardi, L. Biancone, G. Camussi, G. P. Segoloni, M. De Cal, P. Lentini, A. Clementi, G. M. Virzi, E. Scalzotto, A. Lacquaniti, V. Donato, M. R. Fazio, S. Lucisano, V. Cernaro, R. Lupica, M. Buemi, I. Helvaci, E. Anik, M. Wani, D. I. Wani, D. M. A. Bhat, D. K. Banday, D. M. S. Najar, D. A. R. Reshi, D. N. A. Palla, P. Iglesias, T. Olea, C. Vega-Cabrera, M. Heras, M. A. Bajo, G. Del Peso, M. J. Arias, R. Selgas, J. J. Diez, E. Daher, P. L. Costa, E. N. S. Pereira, R. D. P. Santos, K. L. Abreu, G. Silva Junior, E. D. B. Pereira, M. Raimundo, S. Crichton, Y. Syed, J. Martin, C. Whiteley, D. Bennett, M. Ostermann, A. Gjyzari, N. Thereska, A. Koroshi, M. Barbullushi, S. Kodra, A. Idrizi, A. Strakosha, E. Petrela, J. Lemmich Smith, A. Klimenko, E. Tuykhmenev, S. Villevalde, Z. Kobalava, S. Avdoshina, E. Tyukhmenev, M. Efremovtseva, H. Hayashi, S. Suzuki, K. Kataoka, Y. Kondoh, H. Taniguchi, D. Sugiyama, K. Nishimura, W. Sato, S. Maruyama, S. Matsuo, Y. Yuzawa, D. Geraldine, F. Muriel, H. Alexandre, R. Eric, P. Fu, M. Pozzato, F. Ferrari, P. Cecere, P. Mesiano, A. Vallero, S. Livigni, F. Quarello, L. Hudier, O. Decaux, A. Haddj-Elmrabet, L. Mandart, M. Lino-Daniel, F. Bridoux, E. Renaudineau, T. Sawadogo, P. Le Pogamp, C. Vigneau, D. Famee, H. M. Koo, H. J. Oh, S. H. Han, K. H. Choi, S.-W. Kang, M. Mehdi, M. Nicolas, C. Mariat, P. Shah, V. B. Kute, A. Vanikar, M. Gumber, H. Patel, H. Trivedi, C. Manetos, S. Poulaki, E.-S. Tripodaki, A. Papastylianou, C. Routsi, K. Uchida, U. Kensuke, K. Yamagata, C. Saitou, M. Okada, G. Chita, M. Davies, Y. Veriawa, S. Naicker, P. Mukhopadhyay, D. Mukherjee, R. Mishra, M. Kar, D. Zickler, H. Wesselmann, R. Schindler, E. Gutierrez, J. Egido, A. Rubio-Navarro, I. Buendia, L. M. Blanco-Colio, O. Toldos, F. Manzarbeitia, A. De Lorenzo, R. Sanchez, M. Praga, J. A. Moreno, M. Y. Kim, N. R. Kang, H. R. Jang, J. E. Lee, W. Huh, Y.-G. Kim, D. J. Kim, S.-C. Hong, J.-S. Kim, H. Y. Oh, T. Okamoto, K. Kamata, S. Naito, H. Tazaki, S. Kan, L.-G. Anne-Kathrin, K. Matthias, T. Speer, L. Andreas, G. Heinrich, V. Thomas, A. Poppleton, F. Danilo, C.-F. Lai, V.-C. Wu, C.-C. Shiao, T.-M. Huang, K.-D. Wu, M. Bedford, C. Farmer, J. Irving, P. Stevens, F. Patera, F. Mattozzi, S. Battistoni, R. M. Fagugli, M. Y. Park, S. J. Choi, J. G. Kim, S. D. Hwang, H. Xie, H. Chen, S. Xu, Q. He, J. Liu, W. Hu, Z. Liu, M. Dalboni, R. Blaya, B. M. Quinto, R. Narciso, M. Oliveira, J. Monte, M. Durao, M. Cendoroglo, M. Batista, A. L. Hanemann, A. Liborio, A. Martins, M. C. C. Pinheiro, G. Meneses, R. De Paula Pessoa, M. Sousa, F. S. M. Bezerra, P. L. M. M. Albuquerque, J. B. Lima, C. B. Lima, M. D. S. B. Veras, T. Nemoto Matsui, C. Totoli, M. C. Cruz Andreoli, M. P. Vilela Coelho, N. K. Guimaraes de Souza, A. L. Ammirati, F. De Carvalho Barreto, B.-H. Ferraz Neto, B. Fortunato Cardoso Dos Santos, A. Abraham, G. Abraham, M. Mathew, P. M. A. Duarte, F. B. Duarte, E. M. Barros, F. Q. S. Castro, H. Palomba, I. Castro, S. R. Sousa, A. N. Jesus, T. Romano, E. Burdmann, L. Yu, S. H. Kwon, J. Y. You, Y. K. Hyun, S. A. Woo, J. S. Jeon, H. J. Noh, D. C. Han, L. Tozija, Z. Petronievic, G. Selim, I. Nikolov, O. Stojceva-Taneva, K. Cakalaroski, A. Lukasz, J. Beneke, J. Menne, M. Schiffer, N. Polanco, E. Hernandez, V. Gutierrez Millet, E. Gonzalez Monte, E. Morales, L. Francisco Javier, G.-F. Nuria, M.-G. Jose Maria, M. Bes Rastrollo, A. Angioi, M. Conti, R. Cao, A. Atzeni, G. Pili, V. Matta, E. Murgia, P. Melis, V. Binda, A. Pani, F. Thome, F. Leusin, E. Barros, C. Morsch, A. Balbinotto, C. Pilla, V. Premru, J. Buturovic-Ponikvar, R. Ponikvar, A. Marn-Pernat, B. Knap, J. Kovac, J. Gubensek, B. Kersnic, L. Krnjak, M. Prezelj, J. Granatova, M. Havrda, Z. Hruskova, K. Kratka, O. Remes, M. Mokrejsova, M. Bolkova, V. Lanska, I. Rychlik, M. D. Uniacke, R. J. Lewis, S. Harris, P. Roderick, N. Martin, K. Ulrich, B. Jan, B. Jorn, B. Reinhard, K. Jan, H. Hermann, F. Meyer Tobias, R. Leyla, M. W. Schmidt Bernhard, S. Harald, S. Jurgen, K. Tanja, S. Mario, E. Sang Hi, M. Claus, V. Frank, S. Aleksej, S. Sengul, S. Robert, W. Karin, G. Feikah, F. Menne Tobias, N. Meyer Tobias, G. Beutel, S. Fleig, J. Steinhoff, T. Meyer, C. Hafer, J. Bramstedt, V. Busch, M. Vischedyk, U. Kuhlmann, W. Ries, S. Mitzner, S. Mees, S. Stracke, J. Nurnberger, P. Gerke, M. Wiesner, B. Sucke, M. Abu-Tair, A. Kribben, N. Klause, F. Merkel, S. Schnatter, E. Dorresteijn, O. Samuelsson, R. Brunkhorst, G. Stec-Hus Registry, A. Reising, F.-C. Bange, M. Hiss, F. Vetter, S. M. Bode-Boger, J. Martens-Lobenhoffer, B. M. W. Schmidt, J. T. Kielstein, H. S. Shin, Y. S. Jung, and H. Rim

Subjects
Transplantation, Nephrology
Published
2012
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9. Clinical Nephrology - Lab methods and other markers

Author

W. Kleophas, B. Bieber, B. Robinson, J. Duttlinger, D. Fliser, G. Lonneman, L. Rump, R. Pisoni, F. Port, H. Reichel, R. Daniela, A. Ciocalteu, I. A. Checherita, I. Peride, D. M. Spataru, A. Niculae, K. Laetitia, K. Amna, D. Laurence, H.-A. Aoumeur, M. Flamant, J.-P. Haymann, E. Letavernier, E. Vidal-Petiot, J.-J. Boffa, F. Vrtovsnik, F. Bianco, G. Pessolano, M. Carraro, G. O. Panzetta, N. Ebert, J. Gaedeke, O. Jakob, M. Kuhlmann, P. Martus, M. Van der Giet, E. Scha ner, I. Khan, Y. Law, K. Turgutalp, O. Ozhan, E. Gok Oguz, A. Kiykim, C. Donadio, Z. N. Hatmi, M. Mahdavi-Mazdeh, E. Morales, V. Gutierrez-Millet, J. Rojas-Rivera, A. Huerta, E. Gutierrez, E. Gutierrez-Solis, N. Polanco, J. Caro, E. Gonza z, M. Praga, M. Marco Mayayo, J. Valdivielso, M. Marti z, E. Fernaez Giraez, G. Obrador, N. Olvera, D. Ortiz de la Pe, V. Gutie ez, A. Villa, B. Redal-Baigorri, K. Sombolos, D. Tsakiris, J. Boletis, D. Vlahakos, K. Siamopoulos, V. Vargiemezis, P. Nikolaidis, C. Iatrou, E. Dafnis, C. Argyropoulos, K. Xynos, D. Schock-Kusch, Y. Shulhevich, S. Geraci, J. Hesser, D. Stsepankou, S. Neudecker, S. Koenig, F. Hoecklin, J. Pill, N. Gretz, F. Schweda, A. Schreiber, K. Kudo, T. Konta, S. O. Choi, J. S. Kim, M. K. Kim, J. W. Yang, B. G. Han, P. Delanaye, E. Cavalier, I. Masson, M. Mehdi, M. Nicolas, B. Lambermont, B. Dubois, P. Damas, J.-M. Krzesinski, J. Morel, A. Lautrette, M. Christophe, A. Gagneux-Brunon, F. Anne, L. Fre (C)ric, S. Bevc, R. Ekart, R. Hojs, M. Gorenjak, L. Puklavec, N. Hashimoto, A. Suzuki, K. Mitsumoto, M. Shimizu, K. Niihata, A. Kawabata, Y. Sakaguchi, T. Hayashi, T. Shoji, N. Okada, Y. Tsubakihara, T. Hamano, C. Nakano, N. Fujii, Y. Obi, S. Mikami, K. Inoue, I. Matsui, Y. Isaka, H. Rakugi, V. Edvardsson, B. Siguron, M. Thorsteinsdottir, R. Palsson, J. Matsumoto, N. Miyazaki, I. Murata, G. Yoshida, K. Morishita, H. Ushikoshi, K. Nishigaki, S. Ogura, S. Minatoguchi, U. Werneke, M. Ott, E. Salander-Renberg, D. Taylor, B. Stegmayr, S. Surel, M. Wenzlova, G. Silva Junior, A. P. Vieira, A. Couto Bem, M. Alves, A. Torres, G. Meneses, A. Martins, A. Liborio, E. Daher, G. Gluhovschi, M. Modilca, L. Daminescu, C. Gluhovschi, S. Velciov, L. Petrica, F. Gadalean, C. Balgradean, H. H. Schmeiser, M. Kolesnyk, N. Stepanova, L. Surzhko, N. Stashevska, V. Filiopoulos, D. Hadjiyannakos, D. Arvanitis, K. Panagiotopoulos, D. Vlassopoulos, N. Kaesler, T. Schettgen, E. Magdeleyns, V. Brandenburg, C. Vermeer, J. Floege, T. Kr, O. Randone, M. Ferraresi, E. Aroasio, A. Depascale, S. Scognamiglio, V. Consiglio, G. B. Piccoli, L. V. Jensen, S. Lizakowski, P. Rutkowski, L. Tylicki, M. Renke, B. Sulikowska, R. Donderski, R. Bednarski, Z. Heleniak, M. Przybylska, J. Manitius, B. Rutkowski, L. Bobrova, N. Kozlovskaya, K. Kanayama, M. Hasegawa, F. Kitagawa, J. Ishii, Y. Yuzawa, K. Tanaka, K. Sakai, S. Hara, Y. Suzuki, Y. Tanaka, A. Aikawa, F. Hinoshita, N. Hamano, E. Sasaki, A. Kato, T. Katsuki, A. Katsuma, E. Imai, M. Shibata, M. Tada, T. Shimbo, Y. Kikuchi, S. Oka, T. Muramatsu, N. Yanagisawa, K. Fukutake, Y. Yamamoto, A. Ajisawa, K. Tsuchiya, K. Nitta, M. Ando, X. Liang, P. Wang, Z. Liu, Z. Zhao, V. Luyckx, S. Bowker, A. Miekle, E. Toth, R. Heguilen, A. Malvar, R. Hermes, L. Cohen, G. Muguerza, B. Lococo, A. Bernasconi, O. Loboda, I. Dudar, V. Krot, V. Alekseeva, M. Ichinose, N. Sasagawa, K. Toyama, A. Saito, Y. Kayamori, D. Kang, H. W. Kim, K. Yoshioka, M. Hara, K. Ohashi, A. Maksudova, T. Khalfina, A. Cuoghi, E. Bellei, M. Caiazzo, S. Bergamini, G. Palladino, E. Monari, A. Tomasi, E. Loiacono, R. Camilla, V. Dapr, L. Morando, R. Gallo, L. Peruzzi, M. Conrieri, M. Bianciotto, F. M. Bosetti, R. Coppo, L. DI Lullo, F. Floccari, R. Rivera, A. Granata, R. Faiola, C. Feliziani, A. Villani, M. Malaguti, A. Santoboni, K. Kyriaki, J. Droulias, M. Bogdanova, V. V. Rameev, A. H. Simonyan, L. V. Kozlovskaya, M. R. Altiparmak, S. Trabulus, N. Akalin, A. S. Yalin, A. Esenkaya, S. F. Yalin, K. Serdengeae(C), D. Arita, T. Cunha, J. Perez, M. Sakata, L. Arita, M. Nogueira, Z. Jara, N. Souza, D. Casarini, M. Metzger, M. Vallet, A. Karras, M. Froissart, B. Stengel, P. Houillier, K. Paul, D. Kretzschmar, A. Yilmaz, B. Ba hlein, S. Titze, H.-R. Figulla, G. Wolf, M. Busch, Y. Korotchaeva, N. Gordovskaya, L. Kozlovskaya, K. P. Ng, P. Sharma, S. Stringer, M. Jesky, M. Dutton, C. Ferro, P. Cockwell, S. J. Moon, S. C. Lee, S. Y. Yoon, J. E. Lee, S. J. Han, B. Anna, T. Kirsch, L. Svjetlana, P. Joon-Keun, B. Jan, K. Johanna, H. Haller, M. Haubitz, A. Smirnov, I. Kayukov, N. Rafrafi, O. Degtereva, V. Dobronravov, M. Koch, H. Stefan, G. Dika, M.-H. Antoine, C. Husson, J. Kos, M. Milic, M. Fucek, D. Cvoriocec, M.-F. Bourgeade, J. L. Nortier, B. Jelakovic, E. H. Nawal, M. Naoufal, M. Nabila, E. M. Fadwa, E. K. Salma, B. Nisrine, Z. Mohamed, M. Guislaine, B. Mohamed Gharbi, R. Benyounes, G. G. Sotila, R. Sorin, D. Irina Magdalena, C. Roxana, R. Claudia, F. Correa Barcellos, P. H. Hallal, M. Bohlke, F. Boscolo Del Vechio, A. Reges, I. Santos, G. Mielke, M. Fortes, B. Antunez, M. Laganovic, I. Vukovic Lela, S. Karanovic, J. Seric, V. Premuic, M. Fitrek, L. Fodor, T. Meljkovic Vrkic, V. Bansal, D. Hoppensteadt, and J. Fareed

Subjects
Transplantation, medicine.medical_specialty, Nephrology, business.industry, Medicine, Medical physics, Clinical nephrology, business
Published
2012
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11. Discussion of paper by A. Shabbir, Q. Huang, G. Baeza, D. Vlassopoulos, Q. Chen, R. H. Colby, N. J. Alvarez and O. Hassager, entitled ‘Nonlinear shear and uniaxial extensional rheology of polyether-ester-sulfonate copolymer ionomer melts’

Author

UCL - SST/IMCN/BSMA - Bio and soft matter, A. Shabbir, Q. Huang, G. Baeza, D. Vlassopoulos, Q. Chen, R. H. Colby, N. J. Alvarez, O. Hassager, Zuowei Wang, Constantino Creton, Van Ruymbeke, Evelyne, Salvatore Coppola, Jorge Ramirez, UCL - SST/IMCN/BSMA - Bio and soft matter, A. Shabbir, Q. Huang, G. Baeza, D. Vlassopoulos, Q. Chen, R. H. Colby, N. J. Alvarez, O. Hassager, Zuowei Wang, Constantino Creton, Van Ruymbeke, Evelyne, Salvatore Coppola, and Jorge Ramirez

Published
2017

12. Carnitine Metabolism and Deficit - When Supplementation is Necessary?

Author

Athanasios Evangeliou and D Vlassopoulos

Subjects
medicine.medical_specialty, Cirrhosis, medicine.medical_treatment, Pharmaceutical Science, Carnitine, Internal medicine, Diabetes mellitus, Diabetes Mellitus, Animals, Humans, Medicine, Renal Insufficiency, Heart Failure, business.industry, Catabolism, Metabolism, medicine.disease, Mitochondria, Muscle, Endocrinology, Carnitine biosynthesis, Hemodialysis, Energy Metabolism, business, Primary Carnitine Deficiency, Biotechnology, medicine.drug
Abstract

Carnitine is an ammo acid derivative found in high energy demanding tissues (skeletal muscles, myocardium, the liver and the suprarenal glands). It is essential for the intermediary metabolism of fatty acids. Carnitine is indispensable for beta-oxidation of long-chain fatty acids in the mitochondria but also regulates CoA concentration and removal of the produced acyl groups. AcylCoAs act as restraining factor for several enzymes participating in intermediary metabolism. Transformation of AcylCoA into acylcarnitine is an important system for removing the toxic acyl groups. Although primary deficiency is unusual, depletion due to secondary causes, such as a disease or a medication side effect, can occur. Primary carnitine deficiency is caused by a defect in plasma membrane carnitine transporter in muscle and kidneys. Secondary carnitine deficiency is associated with several inborn errors of metabolism and acquired medical or iatrogenic conditions, for example in patients under valproate and zidovuline treatment. In cirrhosis and chronic renal failure, carnitine biosynthesis is impaired or carnitine is lost during hemodialysis. Other chronic conditions like diabetes mellitus, heart failure, Alzheimer disease may cause carnitine deficiency also observed in conditions with increased catabolism as in critical illness. Preterm neonates develop carnitine deficiency due to impaired proximal renal tubule carnitine re-absorption and immature carnitine biosynthesis. Carnitine stabilizes the cellular membrane and raises red blood cell osmotic resistance but has no metabolic influence on lipids in dialysis patients. L-Carnitine has been administered in senile dementia, metabolic nerve diseases, in HIV infection, tuberculosis, myopathies, cardiomyopathies, renal failure anemia and included in baby foods and milk.

Published
2003
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13. Blood and Peritoneal Levels of Endothelin in Continuous Ambulatory Peritoneal Dialysis Patients

Author

Gilbert Deray, Claude Jacobs, Geneviève Maistre, Alain Carayon, and D. Vlassopoulos

Subjects
Male, medicine.hormone, medicine.medical_specialty, medicine.medical_treatment, Hypertonic Solutions, Urology, urologic and male genital diseases, Peritoneal dialysis, Nephropathy, Endothelins, Peritoneal Dialysis, Continuous Ambulatory, Reference Values, Dialysis Solutions, Blood plasma, medicine, Ascitic Fluid, Humans, Aged, business.industry, Peritoneal fluid, Continuous ambulatory peritoneal dialysis, Middle Aged, medicine.disease, Endothelin 1, female genital diseases and pregnancy complications, Surgery, Ambulatory, Kidney Failure, Chronic, Female, Isotonic Solutions, business
Abstract

We have determined the plasma levels of endothelin-1 (ET-1) in patients with end-stage renal disease treated with continuous ambulatory peritoneal dialysis (CAPD). In 10 CAPD patients mean plasma ET levels (7.01 +/- 0.5 pg/ml) were found higher than in normal subjects (3.6 +/- 0.6 pg/ml). Peritoneal clearance of ET-1 was 1.58 +/- 0.12 ml/min and 2.3 +/- 0.2 ml/min during an isotonic peritoneal exchange and a hypertonic exchange, respectively. Plasma ET-1 levels decreased slightly but significantly during a hypertonic 4-hour exchange (from 7.01 +/- 0.5 to 6.14 +/- 0.4 pg/ml) (p0.05) and were not modified by an isotonic 4-hour exchange (from 5.7 +/- 0.5 to 6.4 +/- 0.4 pg/ml). ET-1 is known to be an important vascular stimulant and thus elevated ET-1 levels may play a role in the genesis of cardiovascular complications which are the leading cause of mortality in these patients.

Published
1995
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14. IgA nephropathy in association with Crohn's disease: A case report and brief review of the literature

Author

Filiopoulos, V. Trompouki, S. Hadjiyannakos, D. Paraskevakou, H. Kamperoglou, D. Vlassopoulos, D.

Subjects
urologic and male genital diseases
Abstract

A case of immunoglobulin A nephropathy (IgAN) complicating a 10-year history of biopsy-proven Crohn's disease in a 31-year-old man is described. The patient presented with mild proteinuria and impaired renal function in the setting of an exacerbation of Crohn's disease. Renal biopsy showed IgAN. The patient responded to steroid treatment with clinical remission of the bowel disease and improvement of renal function, while proteinuria remained unchanged. IgA glomerulonephritis is rarely associated with Crohn's disease with only a few previously described cases. We briefly review these cases together with an overview of potential pathophysiological connections between these two diseases. © 2010 Informa UK Ltd.

Published
2010

15. Fully systolic FFT architecture for giga-sample applications

Author

Babionitakis, K. Chouliaras, V.A. Manolopoulos, K. Nakos, K. Reisis, D. Vlassopoulos, N.

Subjects
Hardware_ARITHMETICANDLOGICSTRUCTURES
Abstract

We present a novel 4096 complex-point, fully systolic VLSI FFT architecture based on the combination of three consecutive radix-4 stages resulting in a 64-point FFT engine. The outcome of cascading these 64-point FFT engines is an improved architecture that efficiently processes large input data sets in real time. Using 64-point FFT engines reduces the buffering and the latency to one third of a fully unfolded radix-4 architecture, while the radix-4 schema simplifies the calculations within each engine. The proposed 4096 complex point architecture has been implemented on a FPGA achieving a post-route clock frequency of 200 MHz resulting in a sustained throughput of 4096 point/20.48 μs. It has also been implemented on a high performance 0.13 μm, 1P8M CMOS process achieving a worst-case (0.9 V, 125 C) post-route clock frequency of 604.5 MHz and a sustained throughput of 4096 point/3.89 μs while consuming 4.4 W. The architecture is extended to accomplish FFT computations of 16K, 64K and 256K complex points with 352, 256 and 188 MHz operating frequencies respectively. © 2009 Springer Science+Business Media, LLC.

Published
2010

16. Viscoelasticity of Semifluorinated Alkanes at the Air—Water Interface

Author

C. Christopoulou, D. Vlassopoulos, U. Jonas, C. Clark, Albert Co, Gary L. Leal, Ralph H. Colby, and A. Jeffrey Giacomin

Subjects
Langmuir, Materials science, Rheology, Chemical physics, Air water interface, Monolayer, Nanotechnology, Surface pressure, Micelle, Viscoelasticity, Macromolecule
Abstract

We have studied the viscoelastic properties of semifluorinated alkanes F(CF2)n(CH2)mH (referred as FnHm) confined at the air‐water interface. These specially synthesized model doubly‐hydrophobic macromolecules of varying architecture reside at the air‐water interface in the form of well‐defined disk‐like surface micelles that minimize the free energy. Pressure area isotherms performed on Langmuir monolayers of these micelles indicated two transitions: one at about 4 mN/m and a second at about 8 mN/m. In both regimes a solid‐like viscoelastic response was probed. In each regime the values of both the storage and the loss surface moduli increased with surface pressure. These findings are discussed in view of recent theoretical developments and provide opportunities for manipulating surface structure and rheology of such types of complex macromolecules. Finally, the effect of architecture on this surface structure—rheology interplay has been also addressed.

Published
2008
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17. Asymmetric caging in soft colloidal mixtures

Author

C. Mayer E. Zaccarelli E. Stiakakis C. N. Likos F. Sciortino A. Munam M. Gauthier N. Hadjichristidis H. Iatrou P. Tartaglia H. Löwen D. Vlassopoulos

Subjects
Condensed Matter::Soft Condensed Matter, Θετικές Επιστήμες, Science
Abstract

The long-standing observations that different amorphous materials exhibit a pronounced enhancement of viscosity and eventually vitrify on compression or cooling continue to fascinate and challenge scientists1, on the ground of their physical origin and practical implications. Glass formation is a generic phenomenon, observed in physically quite distinct systems that encompass hard and soft particles. It is believed that a common underlying scenario2,3, namely cage formation, drives dynamical arrest, especially at high concentrations. Here, we identify a novel, asymmetric glassy state in soft colloidal mixtures, which is characterized by strongly anisotropically distorted cages, bearing similarities to those of hard-sphere glasses under shear. The anisotropy is induced by the presence of soft additives. This phenomenon seems to be generic to soft colloids and its origins lie in the penetrability of the constituent particles. The resulting phase diagram for mixtures of soft particles is clearly distinct from that of hard-sphere mixtures and brings forward a rich variety of vitrified states that delineate an ergodic lake in the parameter space spanned by the size ratio between the two components and by the concentration of the additives. Thus, a new route opens for the rational design of soft particles with desired tunable rheological properties. © 2008 Macmillan Publishers Limited. All rights reserved.

Published
2008

18. Architecturally Complex Polymers: Viscoelasticity and Extensional Rheology

Author

E. van Ruymbeke, M. Kapnistos, E. B. Muliawan, D. Vlassopoulos, A. Hirao, N. Hadjichristidis, Albert Co, Gary L. Leal, Ralph H. Colby, and A. Jeffrey Giacomin

Subjects
chemistry.chemical_classification, Work (thermodynamics), Materials science, chemistry, Rheology, Dilation (morphology), Modulus, Extensional viscosity, Polymer, Statistical physics, Strain hardening exponent, Composite material, Viscoelasticity
Abstract

We test the coarse‐grained time‐marching model we developed for predicting the linear viscoelastic properties of branched polymers from the knowledge of their molecular structure on several new model architectures. Based on three viscoelastic parameters, i.e., the Rouse time of an entanglement segment, the plateau modulus and the entanglement molecular weight, this model uses the ingredients of the tube‐based theories of McLeish and co‐workers, and its implementation is based on a time‐marching algorithm. With a new way to account for the motion of the molecular segments localized between two branching points and within the framework of dynamic tube dilation (using the extended criteria of Graessley), this conceptual approach was already successfully applied to linear, star, H and pom‐pom polymers. In this work, we extend our work to tree‐like polymers. Then, based on the predictions obtained for the linear data, we extended the model for predicting the non‐linear rheology, following the approach proposed by McLeish and Larson, and Blackwell et al. We consider in particular the case of model symmetric Cayley tree polybutadienes and poly(methyl methacrylates) having 2, 3 or 4 generations with branches of varying degree of entanglements. In addition to systematic linear frequency sweep measurements, we performed uniaxial elongation measurements using the SER fixture. The samples tested exhibited significant strain hardening compared to the linear analogues at lower and intermediate Hencky strain rates. The extracted effective steady extensional viscosity scales with the elongational rate with a power exponent of about −0.5, in agreement with earlier findings with linear polystyrenes.We test the coarse‐grained time‐marching model we developed for predicting the linear viscoelastic properties of branched polymers from the knowledge of their molecular structure on several new model architectures. Based on three viscoelastic parameters, i.e., the Rouse time of an entanglement segment, the plateau modulus and the entanglement molecular weight, this model uses the ingredients of the tube‐based theories of McLeish and co‐workers, and its implementation is based on a time‐marching algorithm. With a new way to account for the motion of the molecular segments localized between two branching points and within the framework of dynamic tube dilation (using the extended criteria of Graessley), this conceptual approach was already successfully applied to linear, star, H and pom‐pom polymers. In this work, we extend our work to tree‐like polymers. Then, based on the predictions obtained for the linear data, we extended the model for predicting the non‐linear rheology, following the approach proposed...

Published
2008
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19. Decoding the Viscoelastic Response of Polydisperse Star∕Linear Polymer Blends

Author

L. Balacca, E. van Ruymbeke, S. Coppola, S. Righi, D. Vlassopoulos, Albert Co, Gary L. Leal, Ralph H. Colby, and A. Jeffrey Giacomin

Subjects
chemistry.chemical_classification, Materials science, Polybutadiene, chemistry, Rheology, Dispersity, Molar mass distribution, Thermodynamics, Polymer blend, Polymer, Composite material, Branching (polymer chemistry), Viscoelasticity
Abstract

It is well known that polydispersity and branching have important and, at the same time, hardly predictable effects on the rheological and processing properties of industrial polymers. In the literature, many studies have been undertaken in order to predict the rheology of polydisperse linear polymers and monodisperse, well‐defined, branched polymers. Industrial polymers are usually, simultaneously polydisperse and branched, exhibiting a much more complex viscoelastic behaviour. When polydispersity and branching are both present, many different relaxation processes are indeed active and sometimes coupled. In order to understand the viscoelastic behaviour of such a class of complex materials, we investigated the rheology of several blends of polydisperse linear and stars polymers with the help of a coarse grained—tube model. A series of polydisperse star/linear polybutadiene blends characterized by different composition and arm average molecular weight was prepared. Linear “parent” polymers were synthesized via anionic polymerization. A coupling agent was introduced in a second stage in order to obtain the blends. In order to characterize the composition of the blends, light scattering data were performed for determining their molar mass distributions (MMD). Then, using an adequate statistical approach, MMD were divided into different categories of architectures. We obtained a full set of linear and non‐linear rheological data. Then, we extended our tube‐based model to predict their linear viscoelasticity. This requires several modifications of the initial model in order to deal with a very large number of different particles and star molecules having arms of different lengths. The non‐linear rheological response was analyzed with special attention to the time‐strain separability at short and long times, whereas the response to uniaxial extension was also investigated.

Published
2008
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20. High performance 16K, 64K, 256K complex points VLSI systolic FFT architectures

Author

Manolopoulos, K. Nakos, K. Reisis, D. Vlassopoulos, N. and Chouliaras, V. A.

Abstract

Targeting to improving the efficiency of real-time Fourier Transform computations with large input data sets, this paper presents the design and the VLSI implementation of 16K, 64K and 265K complex points Fast Fourier Transform (FFT) systolic architectures. These organizations are deeply pipelined to maximize the operating frequency and follow the approach of decomposing the transforms into 64-point FFT computations to minimize the buffer size between consecutive stages. The resulting organizations achieve real time performance on testing and observation applications. They include simple processing elements and they are scalable with respect to the operating frequency and data width. Validation on FPGA showed operation at 250MHz and 125MHz for the 16K and the 64K architectures with throughput 1Gs/s and 500Ms/s respectively. The VLSI implementations of the proposed 16K, 64K and 265K architectures achieve post-route clock frequencies of 352, 256.5, and 188 MHz respectively and they can sustain throughputs of 1.4Gs/s, 1Gs/s and 188Ms/s.

Published
2007

21. Entangled Dendritic Polymers and Beyond:0.167em Rheology of Symmetric Cayley-Tree Polymers and Macromolecular Self-Assemblies

Author

E. van Ruymbeke K. Orfanou M. Kapnistos H. Iatrou M. Pitsikalis N. Hadjichristidis D. J. Lohse D. Vlassopoulos

Subjects
Condensed Matter::Soft Condensed Matter, Θετικές Επιστήμες, Science
Abstract

We present linear rheological data on a series of anionically synthesized, model symmetric Cayley-tree polybutadienes having 2 or 3 generations with entangled branches. The signature of each layer relaxation is evident, in both the plateau modulus (that scales with the volume fraction of the unrelaxed layers) and the terminal relaxation as a distinct contribution, well-separated in time. Using a robust tube-model analysis of the viscoelastic relaxation of entangled polymers of given architecture, which is based on the concept of hierarchy of motion in branched structures, we describe quantitatively the frequency spectra without adjustable parameters; the needed plateau modulus, entanglement molecular weight, and Rouse time of an entanglement segment are taken from the data. Last, but not least, we show that this approach can be successfully applied to account for the rheology of macromolecular self-assemblies, such as the Cayley-tree-like associations of telechelic, mono-co-functionalized star polymers. The implications of the latter findings in providing pathways for the analysis of complex soft superstructures are evident. © 2007 American Chemical Society.

Published
2007

23. Tailoring the Flow of Soft Glasses by Soft Additives

Author

E. Zaccarelli C. Mayer A. Asteriadi C. N. Likos F. Sciortino J. Roovers H. Iatrou N. Hadjichristidis P. Tartaglia H. Löwen D. Vlassopoulos

Subjects
Condensed Matter::Soft Condensed Matter, Θετικές Επιστήμες, Science, Condensed Matter::Disordered Systems and Neural Networks
Abstract

We examine the vitrification and melting of asymmetric star polymer mixtures by combining rheological measurements with mode coupling theory. We identify two types of glassy states, a single glass, in which the small component is fluid in the glassy matrix of the big one, and a double glass, in which both components are vitrified. Addition of small-star polymers leads to melting of both glasses, and the melting curve has a nonmonotonic dependence on the star-star size ratio. The phenomenon opens new ways for externally steering the rheological behavior of soft matter systems. © 2005 The American Physical Society.

Published
2005

24. Depletion and cluster formation in soft colloid - polymer mixtures

Author

E Stiakakis G Petekidis D Vlassopoulos C. N Likos H Iatrou N Hadjichristidis J Roovers

Subjects
Condensed Matter::Soft Condensed Matter, Θετικές Επιστήμες, Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The dynamics of colloidal star - linear homopolymer mixtures is investigated by photon correlation spectroscopy. In dilute star solutions, osmotic forces due to the added polymers lead initially to a shrinkage of the stars and eventually, at higher polymer concentrations, to stable star clusters. Furthermore, concentrated glassy star solutions melt upon addition of small amounts of linear polymers, as manifested by the remarkable speed-up of the star self-diffusion. Quantitative description of the experimental findings is provided by calculations of the effective star-star pair potential. © EDP Sciences.

Published
2005

25. Caratterizzazione dei primi stadi della cristallizzazione quiescente di polimeri termoplastici mediante spettroscopia dinamico-meccanica

Author

COPPOLA, SALVATORE, GRIZZUTI, NINO, D. VLASSOPOULOS, F.GRECO,S.GUIDO,P.L.MAFFETTONE,M.MINALE, Coppola, Salvatore, D., Vlassopoulo, and Grizzuti, Nino

Subjects
POLIMERI, CRISTALLIZZAZIONE, REOLOGIA
Abstract

Nel presente lavoro sono studiati i primi stadi della cristallizzazione dal fuso di un polimero termoplastico mediante spettroscopia dinamico-meccanica, adottando una tecnica di "inverse quanching" recentemente sviluppata. In questo modo è infatti possibile eseguire esperimenti che richiedano tempi molto lunghi su un sistema "congelato" dove sia il numero che le dimensioni degli sferuliti formatisi rimangono costanti

Published
2004

26. Probing glassy states in binary mixtures of soft interpenetrable colloids

Author

E Stiakakis B M Erwin D Vlassopoulos M Cloitre A Munam M Gauthier H Iatrou N Hadjichristidis and E Stiakakis B M Erwin D Vlassopoulos M Cloitre A Munam M Gauthier H Iatrou N Hadjichristidis

Abstract

We present experimental evidence confirming the recently established rich dynamic state diagram of asymmetric binary mixtures of soft colloidal spheres. These mixtures consist of glassy suspensions of large star polymers to which different small stars are added at varying concentrations. Using rheology and dynamic light scattering measurements along with a simple phenomenological analysis, we show the existence of re-entrance and multiple glassy states, which exhibit distinct features. Cooperative diffusion, as a probe for star arm interpenetration, is proven to be sensitive to the formation of the liquid pockets which signal the melting of the large-star-glass upon addition of small stars. These results provide ample opportunities for tailoring the properties of soft colloidal glasses. © 2011 IOP Publishing Ltd.

Published
2011

27. Conflict-free parallel memory accessing techniques for FFT architectures

Author

Reisis, D. Vlassopoulos, N. and Reisis, D. Vlassopoulos, N.

Abstract

Speeding up fast Fourier transform (FFT) computations is critical for today's real-time systems targeting signal processing and telecommunication applications. Aiming at the performance improvement and the efficiency of FFT architectures, this paper presents an address generation technique which enables a radix-b processor to access in parallel b memory banks without conflicts during each stage's computations. Using kb memory banks at each stage leads to increasing the speedup of the algorithm by a factor of kb. The address generation can be realized in each radix-b stage by the use of lookup tables of size O(kb2) bits. The proposed technique is cost efficient and leads to the design of FFT architectures of high speedup and high sustained throughput. © 2008 IEEE.

Published
2008

31. Long-term effect of low molecular weight heparin on serum lipids in hypertriglyceridemic chronic hemodialysis patients

Author

D, Vlassopoulos, C, Noussias, A, Hadjipetrou, D, Arvanitis, E, Logothetis, P, Magana, K, Katopodis, and V, Hadjiconstantinou

Subjects
Adult, Male, Renal Dialysis, Chronic Disease, Humans, Female, Hyperlipidemias, Heparin, Low-Molecular-Weight, Middle Aged, Lipids, Aged
Abstract

Although low-molecular-weight heparin (LMWH) has been reported to lower serum triglycerides and raise HDL in patients previously receiving classic heparin for hemodialysis by sparing lipoprotein lipase activation, this is not universally accepted. To evaluate this effect we studied 14 hypertriglyceridemic patients on hemodialysis for a median of 61 months (range 6-168 months); six were males and eight females, with a median age of 54 years (range 30-78). Eight patients were on bicarbonate and six on acetate HD. Eight were receiving EPO. All had been given conventional heparin, 102 +/- 5.8 IU/kg, at least for the last six months (control period) before switching to LMWH. Mean LMWH dose was 77 +/- 3.1 IU/kg. Fasting levels of total cholesterol (TC), triglycerides (TG) and HDL were measured monthly during the control period and every trimester for the next 36 months. Serum lipoproteins were measured at months 0 and 36 of the trial. TC, Lp alpha and beta showed no significant change. Serum TG and Lp pre-beta dropped significantly, to almost normal levels. EPO treatment, serum iPTH levels or dialysate buffer did not seem to influence this effect. HDL rose significantly higher in women than in men. It is concluded that LMWH substantially lowered the abnormally high serum TG and Lp pre-beta to almost normal and raised serum HDL in chronic hemodialysis patients.

Published
1997

33. Pefloxacin as first-line treatment in nephrotic syndrome

Author

D. Vlassopoulos, Gilbert Deray, Alain Baumelou, C. Ginsburg, D Toledano, and Claude Jacobs

Subjects
Transplantation, medicine.medical_specialty, Proteinuria, business.industry, medicine.disease, Gastroenterology, Pefloxacin, Nephrosis lipoid, First line treatment, Nephrology, Internal medicine, medicine, medicine.symptom, business, Nephrotic syndrome, medicine.drug
Published
1994
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34. Pefloxacin as first-line treatment in nephrotic syndrome

Author

C, Ginsburg, D, Toledano, G, Deray, D, Vlassopoulos, A, Baumelou, and C, Jacobs

Subjects
Adult, Male, Proteinuria, Nephrotic Syndrome, Adolescent, Glomerulosclerosis, Focal Segmental, Nephrosis, Lipoid, Humans, Female, Glomerulonephritis, Membranous, Pefloxacin
Published
1994

35. Bone disease in CKD 1-5

Author

M. I. Yilmaz, A. Sonmez, M. Saglam, H. Yaman, S. Kilic, T. Eyileten, K. Caglar, Y. Oguz, A. Vuaral, M. Yenicesu, F. Mallamaci, C. Zoccali, S. Mazzaferro, M. Pasquali, S. Rotondi, L. Tartaglione, G. Pirro, M. L. Muci, C. Conte, G. Mandanici, A. Frasheri, F. Pugliese, H. Fehmi, Y. Long, K. Kono, H. Fujii, K. Nakai, S. Goto, J. Shite, K.-i. Hirata, M. Fukagawa, S. Nishi, J. R. Wu-Wong, M. Nakane, Y.-w. Chen, P. Nikolopoulos, A. Vlachopanou, C. Giannaki, V. Siapera, V. Papachristopoulos, C. Gouva, V. Sakhuja, P. Dheerendra, V. Jha, M. Rathi, H. S. Kohli, D. Hadjiyannakos, S. Trompouki, V. Filiopoulos, M. Sonikian, I. Karatzas, K. Panagiotopoulos, D. Vlassopoulos, H. Taskapan, O. Baysal, D. Karahan, O. Ulutas, G. Mircescu, C. Capusa, S. Stancu, M. Badulescu, L. Barsan, N. Dorobantu, D. Maria, E. Mota, I. Yildiz, Y. Sagliker, O. Demirhan, V. Acharya, L. Zhang, O. Golea, A. Sabry, D. Ookalkar, D. Radulescu, L. Garneata, H. Ben Maiz, C. Hsu Chen, J. Prado Rome, M. Benzegoutta, N. Paylar, K. Eyuboglu, E. Karatepe, M. Esenturk, O. Yavascan, S. M. Adam, I. Emir, A. Grzegorzevska, E. Tunc, F. Ocal, E. Usta, V. Shilo, M. M. Mazdeh, R. C. Francesco, N. Levin-Iaina, J. Malyszko, P. Kozminski, E. Koc-Zorawska, M. Mysliwiec, M. Lipan, H. Reichel, J. Ringel, C. Guggenberger, F. Dellanna, C. Teixeira, E. Almeida, M. Raimundo, F. Neves, A. Santana, A. Fortes, F. Abreu, C. Pinto Abreu, Z. El Bouazzaoui, A. Cortesao Costa, E. Nogueira, A. Gomes da Costa, E. ElShafey, A. Alsahow, K. Saran, M. Attia, L. Di Lullo, A. Gorini, A. Cecilia, C. Comegna, C. Galderisi, G. R. Iannacci, M. Vitale, P. Polito, I. Kyritsis, M.-E. Roumelioti, I. Agroyannis, S. Vrachnis, V. Kapelleris, O. Fituri, G. Ismail, A. Donia, S. Sezer, S. Karakan, B. Atesagaoglu, E. Tutal, N. Ozdemir Acar, S. Ozturk, S. Uzun, A. H. Kaya, M. Gursu, B. Kaya, A. Sarbay Kemik, Z. Aydin, S. Karadag, H. Feyizoglu, R. Kazancioglu, and I. Vlad

Subjects
Transplantation, medicine.medical_specialty, Bone disease, Nephrology, business.industry, Internal medicine, medicine, business, medicine.disease
Published
2011
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36. Successful local thrombolysis of an acutely thrombosed AV fistula by recombinant human tissue plasminogen activator

Author

P. Magana, E. Logothetis, D. Vlassopoulos, and V. Hadjiconstantinou

Subjects
Transplantation, medicine.medical_specialty, business.industry, medicine.medical_treatment, Fistula, Thrombolysis, medicine.disease, Tissue plasminogen activator, Surgery, law.invention, Nephrology, law, medicine, Recombinant DNA, business, medicine.drug
Published
1993
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37. Wangiella dermatitidis Peritonitis in a CAPD Patient

Author

D. Arvanitis, G Kouppari, V Hadjiconstantinou, K Papaefstathiou, A Dounavis, D Vlassopoulos, and A Velegraki

Subjects
medicine.medical_specialty, Nephrology, business.industry, medicine.medical_treatment, Internal medicine, medicine, Peritonitis, Wangiella dermatitidis, General Medicine, medicine.disease, business, Gastroenterology, Peritoneal dialysis
Published
2001
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38. Proposal to Solve the Time−Stress Discrepancy of Tube Models.

Author

E. van Ruymbeke, D. Vlassopoulos, M. Kapnistos, CY. Liu, and C. Bailly

Subjects
*MACROMOLECULES, *ALGORITHMS, *VISCOELASTICITY, *DEFORMATIONS (Mechanics), *MOLECULAR weights, *POLYMER viscosity
Abstract

Recently, Liu et al. (Macromolecules 2006, 39, 3093) showed a systematic discrepancy of tube model predictions for describing the apparent plateau modulus of short (weakly entangled) linear chains while predicting very accurately their terminal relaxation times. In the present article, we investigate the origin of this problem, which we call “time-stress discrepancy”, by confronting our time-marching algorithm (TMA) with experimental viscoelastic data of nearly monodisperse linear polymers. We show that the contour length fluctuations of the outer molecular segments are overestimated, not taking into account the fact that a chain needs a short but essential time to be considered in equilibrium in its tube. Indeed, tube models consider that stress relaxation by reptation or contour length fluctuations starts at time t= 0 after an imposed small deformation, whereas in reality, there is a proceeding fast Rouse relaxation, which is especially important for shorter chains. Therefore, we propose to use a new segment coordinate system for describing the contour length fluctuations process, which restores the consistency with the tube definition and ensures that the necessary time for reaching an equilibrated system is equal to the relaxation time of an entanglement segment, τe. Results obtained with the so-corrected TMA model show a very good agreement with experimental data. In particular, the molecular-weight dependence of the apparent plateau modulus, the zero-shear viscosity, and the terminal relaxation time are now correctly predicted. [ABSTRACT FROM AUTHOR]

Published
2010
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42. Geochim. cosmochim. acta

Author

S.A. Wood and D. Vlassopoulos

Subjects
Speciation, Hydrolysis, Aqueous solution, Geochemistry and Petrology, Chemistry, media_common.quotation_subject, Natural water, Inorganic chemistry, Solubility, media_common
Published
1990
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43. Studies on cyanide and thiocyanate in uraemia

Author

H, Yatzidis, D, Koutsicos, D, Vlassopoulos, D, Cristodoulou, and G, Yulis

Subjects
Adult, Male, Cyanides, Humans, Urea, Female, Middle Aged, Thiocyanates, Uremia
Abstract

Cyanide and thiocyanate was measured in blood and in peritoneal lavage solution in patients with advanced or terminal renal failure. The behavior of these substances was comparable to that of normal people. Our finding does not support the hypothesis of an indirect toxicity of urea via its previous conversion to cyanate. Cyanate ion has not been implicated in the toxic status of chronic uraemia.

Published
1981

46. Studies on Cyanide and Thiocyanate in Uraemia

Author

D Koutsicos, D Vlassopoulos, G Yulis, H Yatzidis, and D Cristodoulou

Subjects
Thiocyanate, Cyanide, 030232 urology & nephrology, Biomedical Engineering, Medicine (miscellaneous), Bioengineering, General Medicine, 030204 cardiovascular system & hematology, Normal people, Pharmacology, Cyanate, Biomaterials, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Chronic uraemia, chemistry, Toxicity, Urea, In patient
Abstract

Cyanide and thiocyanate was measured in blood and in peritoneal lavage solution in patients with advanced or terminal renal failure. The behavior of these substances was comparable to that of normal people. Our finding does not support the hypothesis of an indirect toxicity of urea via its previous conversion to cyanate. Cyanate ion has not been implicated in the toxic status of chronic uraemia.

Published
1981
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49. Viscoelasticity and crystallization of poly(ethylene oxide) star polymers of varying arm number and size

Author

Salvatore Coppola, George Floudas, Dimitris Vlassopoulos, Nino Grizzuti, S., Coppola, Grizzuti, Nino, G., Flouda, and D., Vlassopoulos

Subjects
anionic polystyrenes, Materials science, flow-induced crystallization, Oxide, Thermodynamics, Viscoelasticity, law.invention, chemistry.chemical_compound, Differential scanning calorimetry, Rheology, law, polyethylene fractions, General Materials Science, chain entanglements, Crystallization, chemistry.chemical_classification, Ethylene oxide, Star polymer, Mechanical Engineering, Polymer, Condensed Matter Physics, isotactic polypropylene, rheological properties, chemistry, Mechanics of Materials, shear-induced crystallization, equilibrium melting temperature, molecular-weight, Melting point, constraint release
Abstract

We investigated the linear melt viscoelasticity and the crystallization kinetics of a series of model poly(ethylene oxide) stars with different functionalities (f=4-32 arms) and moderately entangled arms (their molecular masses ranging from 5.5 to 12 kg/mol). The limited data in the homogeneous state indicated that the zero-shear viscosity eta(0) was adequately described by the Milner-McLeish model for functionalities f < 32, where the core effect is insignificant; a similar behavior was observed for the recoverable compliance J(e)(0) which depended on both the molecular weight and the number of the arms. Below the melting point, the isothermal crystallization was measured with differential scanning calorimetry and rheology, and analyzed in terms of the Avrami theory, expanding over a wide range of temperatures. The results were supported by additional polarizing optical microscopy data and indicated a slower crystallization kinetics of the stars compared to their linear analogues. They showed a strong dependence of the crystallization rate on the arm molecular weight, whereas the available experimental evidence is suggestive of some functionality dependence as well. (c) 2007 The Society of Rheology. Journal of Rheology

Published
2007
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50. Multiscale Elasticity of Epoxy Networks by Rheology and Brillouin Light Spectroscopy.

Author

Filippidi E, Dhiman AK, Li B, Athanasiou T, Vlassopoulos D, and Fytas G

Abstract

The response of soft materials to an imposed oscillatory stress is typically frequency dependent, with the most utilized frequency range falling in the range of 10 -2 -10 2 rad/s. In contrast to most conventional contact techniques for measuring material elasticity, like tensile or shear rheology and atomic force microscopy, or invasive techniques using probes, such as microrheology, Brillouin light spectroscopy (BLS) offers an optical, noncontact, label-free, submicron resolution and three-dimensional (3D) mapping approach to access the mechanical moduli at GHz frequencies. Currently, the correlation between the experimental viscoelastic (at lower frequencies) and elastic (at higher frequencies) moduli has fundamental and practical relevance, but remains unclear. We utilize a series of solvent-free epoxy polymer networks with variable cross-link density as models to compare the storage modulus, G ', (in the MPa range) obtained from shear rheology and the longitudinal modulus, M ', (in the GPa range) extracted from BLS. Our results show that G ' exhibits a much stronger increase with increasing cross-link density than M ' (by a factor of about 3.5). This finding is discussed in the context of the phantom network model for G ' and Wood's inverse rule of mixtures for M '. The epoxy polymer network displays an unexpectedly fast hypersonic dispersion compared to its uncross-linked precursor. These results testify the importance of obtaining reliable information about the elasticity of networks and will hopefully trigger further investigations in the direction of bridging the elasticity of soft materials at different scales.

Published
2024
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