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Pignata S, Scambia G, Schettino C, Arenare L, Pisano C, Lombardi D, De Giorgi U, Andreetta C, Cinieri S, De Angelis C, Priolo D, Casanova C, Rosati M, Greco F, Zafarana E, Schiavetto I, Mammoliti S, Cecere SC, Salutari V, Scalone S, Farolfi A, Di Napoli M, Lorusso D, Gargiulo P, Califano D, Russo D, Spina A, De Cecio R, Chiodini P, Perrone F, Accinno V, Altavilla C, Andreetta C, Antonelli G, Arenare L, Artioli G, Avola F, Barbara B, Barbato V, Bartoletti M, Bevilacqua S, Bordonaro R, Borghese O, Buonfanti G, Califano D, Camarda F, Canzanella G, Carbone V, Carbone MR, Carlo Stella G, Casanova C, Cassani C, Castagna F, Cattaneo M, Cecere SC, Chiodini P, Cinefra M, Cinieri S, Colombo N, Corsetti S, Dall'Agata M, D'Amico M, Daniele G, De Angelis C, De Cecio R, De Giorgi U, De Marino E, De Matteis G, De Placido S, Del Bene G, Del Giudice A, Del Monte F, Del Sesto M, Di Napoli M, Donini M, Drudi G, Falcone G, Farolfi A, Favaretto A, Ferrera G, Florio M, Forestieri V, Gallo MS, Gallo C, Gargiulo P, Garibaldi F, Gerevini F, Ghizzoni V, Giganti MO, Gimigliano A, Giudice E, Gnocchi N, Gravina A, Greco F, Greggi S, Iaia ML, Ilardi A, Iovine G, Ippoliti G, Irollo G, Isidori I, Lapresa M, Lavenia G, Lombardi D, Longhitano L, Lorusso D, Lucia B, Luzi G, Mammoliti S, Mariano S, Marino V, Marrapese G, Martino M, Matocci R, Mazzoni E, Mercuri D, Mirto M, Mollo G, Montinaro A, Moscatelli M, Mosconi AM, Musacchio L, Nanni N, Natalucci P, Nicoloso MS, Orditura M, Parma GM, Passalacqua R, Pelone M, Perri MT, Perrone F, Perrucci B, Piancastelli A, Piccirillo MC, Piccolo A, Pignata S, Pisano C, Priolo D, Rapisardi S, Ravaglia G, Ribecco T, Ricci C, Roccio M, Romano F, Rosati M, Russo D, Salutari V, Sambataro D, Savio A, Sbriglia A, Scaffa C, Scalone S, Scambia G, Schettino C, Schiavetto I, Sergi C, Sgandurra F, Sorio R, Spina A, Stabile S, Tabaro G, Tambaro M, Tamberi S, Tecchiato A, Trujillo AM, Zaccarelli E, Zafarana E. Carboplatin and paclitaxel plus avelumab compared with carboplatin and paclitaxel in advanced or recurrent endometrial cancer (MITO END-3): a multicentre, open-label, randomised, controlled, phase 2 trial. Lancet Oncol 2023; 24:286-296. [PMID: 37052965 DOI: 10.1016/s1470-2045(23)00016-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 02/16/2023]
Abstract
BACKGROUND Adding immunotherapy to first-line chemotherapy might improve outcomes for patients with advanced or recurrent endometrial cancer. We aimed to compare carboplatin and paclitaxel versus avelumab plus carboplatin and paclitaxel as first-line treatment with avelumab given concurrent to chemotherapy and as maintenance after the end of chemotherapy. METHODS MITO END-3 is an open-label, randomised, controlled, phase 2 trial conducted at 31 cancer institutes, hospitals, and universities in Italy. Eligible patients were aged 18 years or older with histologically confirmed advanced (FIGO stage III-IV) or recurrent endometrial cancer, an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, and no previous systemic anticancer therapy as primary treatment for advanced or metastatic disease. Participants were randomly assigned (1:1) using a computerised minimisation procedure stratified by centre, histology, and stage at study entry, to either receive carboplatin (area under the curve [AUC] 5 mg/mL × min) and paclitaxel (175 mg/m2; standard group) intravenously every 3 weeks for six to eight cycles or avelumab (10 mg/kg intravenously) added to carboplatin and paclitaxel (experimental group) every 3 weeks and then every 2 weeks as a single maintenance treatment after the end of chemotherapy until disease progression or unacceptable toxicity. Patients, treating clinicians, and those assessing radiological examinations were not masked to study treatment. The primary endpoint was investigator-assessed progression-free survival, measured in the intention-to-treat (ITT) population. Patients who received at least one dose of study drug were included in the safety analysis. Experimental group superiority was tested with 80% power and one-tailed α 0·20. This trial is registered with ClinicalTrials.gov (NCT03503786) and EudraCT (2016-004403-31). FINDINGS From April 9, 2018, to May 13, 2021, 166 women were assessed for eligibility and 39 were excluded. 125 eligible patients were randomly assigned to receive carboplatin and paclitaxel (n=62) or avelumab plus carboplatin and paclitaxel (n=63) and included in the ITT population. The median follow-up was 23·3 months (IQR 13·2-29·6) and was similar between the two groups. 91 progression-free survival events were reported, with 49 events in 62 patients in the standard group and 42 events in 63 patients in the experimental group. The median progression-free survival was 9·9 months (95% CI 6·7-12·1) in the standard group and 9·6 months (7·2-17·7) in the experimental group (HR of progression or death 0·78 [60% CI 0·65-0·93]; one-tailed p=0·085). Serious adverse events were reported more frequently in the experimental group (24 vs seven events in the standard group); neutrophil count decrease was the most frequent grade 3-4 adverse event (19 [31%] of 61 patients in the experimental group vs 26 [43%] of 61 patients in the standard group). Two deaths occurred in the experimental group during treatment (one respiratory failure following severe myositis [possibly related to treatment] and one cardiac arrest [not related to treatment]). INTERPRETATION Adding avelumab to first-line chemotherapy deserves further testing in patients with advanced or recurrent endometrial cancer, although consideration of mismatch repair status is warranted. FUNDING Pfizer.
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De Matteis V, Rizzello L, Ingrosso C, Liatsi-Douvitsa E, De Giorgi ML, De Matteis G, Rinaldi R. Cultivar-Dependent Anticancer and Antibacterial Properties of Silver Nanoparticles Synthesized Using Leaves of Different Olea Europaea Trees. Nanomaterials (Basel) 2019; 9:nano9111544. [PMID: 31671618 PMCID: PMC6915347 DOI: 10.3390/nano9111544] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 01/15/2023]
Abstract
The green synthesis of nanoparticles (NPs) is currently under worldwide investigation as an eco-friendly alternative to traditional routes (NPs): the absence of toxic solvents and catalysts make it suitable in the design of promising nanomaterials for nanomedicine applications. In this work, we used the extracts collected from leaves of two cultivars (Leccino and Carolea) belonging to the species Olea Europaea, to synthesize silver NPs (AgNPs) in different pH conditions and low temperature. NPs underwent full morphological characterization with the aim to define a suitable protocol to obtain a monodispersed population of AgNPs. Afterwards, to validate the reproducibility of the mentioned synthetic procedure, we moved on to another Mediterranean plant, the Laurus Nobilis. Interestingly, the NPs obtained using the two olive cultivars produced NPs with different shape and size, strictly depending on the cultivar selected and pH. Furthermore, the potential ability to inhibit the growth of two woman cancer cells (breast adenocarcinoma cells, MCF-7 and human cervical epithelioid carcinoma, HeLa) were assessed for these AgNPs, as well as their capability to mitigate the bacteria concentration in samples of contaminated well water. Our results showed that toxicity was stronger when MCF-7 and Hela cells were exposed to AgNPs derived from Carolea obtained at pH 7 presenting irregular shape; on the other hand, greater antibacterial effect was revealed using AgNPs obtained at pH 8 (smaller and monodispersed) on well water, enriched with bacteria and coliforms.
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Affiliation(s)
- Valeria De Matteis
- Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via Arnesano, 73100 Lecce, Italy.
| | - Loris Rizzello
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, 08028 Barcelona, Spain.
| | - Chiara Ingrosso
- CNR-IPCF S.S. Bari, c/o Department of Chemistry, Università degli Studi di Bari, via Orabona 4, I-70126 Bari, Italy.
| | - Eva Liatsi-Douvitsa
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Maria Luisa De Giorgi
- Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via Arnesano, 73100 Lecce, Italy.
| | - Giovanni De Matteis
- Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via Arnesano, 73100 Lecce, Italy.
| | - Rosaria Rinaldi
- Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via Arnesano, 73100 Lecce, Italy.
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Graudenzi A, Caravagna G, De Matteis G, Antoniotti M. Investigating the relation between stochastic differentiation, homeostasis and clonal expansion in intestinal crypts via multiscale modeling. PLoS One 2014; 9:e97272. [PMID: 24869488 PMCID: PMC4037186 DOI: 10.1371/journal.pone.0097272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 04/16/2014] [Indexed: 12/24/2022] Open
Abstract
Colorectal tumors originate and develop within intestinal crypts. Even though some of the essential phenomena that characterize crypt structure and dynamics have been effectively described in the past, the relation between the differentiation process and the overall crypt homeostasis is still only partially understood. We here investigate this relation and other important biological phenomena by introducing a novel multiscale model that combines a morphological description of the crypt with a gene regulation model: the emergent dynamical behavior of the underlying gene regulatory network drives cell growth and differentiation processes, linking the two distinct spatio-temporal levels. The model relies on a few a priori assumptions, yet accounting for several key processes related to crypt functioning, such as: dynamic gene activation patterns, stochastic differentiation, signaling pathways ruling cell adhesion properties, cell displacement, cell growth, mitosis, apoptosis and the presence of biological noise. We show that this modeling approach captures the major dynamical phenomena that characterize the regular physiology of crypts, such as cell sorting, coordinate migration, dynamic turnover, stem cell niche correct positioning and clonal expansion. All in all, the model suggests that the process of stochastic differentiation might be sufficient to drive the crypt to homeostasis, under certain crypt configurations. Besides, our approach allows to make precise quantitative inferences that, when possible, were matched to the current biological knowledge and it permits to investigate the role of gene-level perturbations, with reference to cancer development. We also remark the theoretical framework is general and may be applied to different tissues, organs or organisms.
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Affiliation(s)
- Alex Graudenzi
- Dept. of Informatics, Systems and Communication, University of Milan-Bicocca, Milan, Italy
- * E-mail:
| | - Giulio Caravagna
- Dept. of Informatics, Systems and Communication, University of Milan-Bicocca, Milan, Italy
| | - Giovanni De Matteis
- Department of Mathematics and Information Sciences, Northumbria University, Newcastle, United Kingdom
| | - Marco Antoniotti
- Dept. of Informatics, Systems and Communication, University of Milan-Bicocca, Milan, Italy
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Bisi F, De Matteis G, Romano S. Calamitic and antinematic orientational order produced by the generalized Straley lattice model. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:032502. [PMID: 24125280 DOI: 10.1103/physreve.88.032502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Indexed: 06/02/2023]
Abstract
We consider here a classical model, consisting of D_{2h}-symmetric particles in a three-dimensional simple-cubic lattice; the pair potential is isotropic in orientation space, and restricted to nearest neighbors. The simplest potential model is written in terms of the squares of the scalar products between unit vectors describing the three interacting arms of the molecules, as proposed in previous literature. Two predominant antinematic couplings of equal strength (+1) are perturbed by a comparatively weaker calamitic one, parameterized by a coupling constant -z ranging in [-1,0]. This choice rules out thermodynamically stable phases endowed with macroscopic biaxiality. The antinematic terms favor states with the corresponding molecular axes mutually orthogonal. Although the low-temperature phase of the special case with null calamitic term (PP0) is uniaxial and antinematically ordered, in the general case presented here both Monte Carlo and molecular-field approaches show that, for z close to zero, the models exhibit a low-temperature uniaxial nematic phase, followed by an antinematic one, and finally by the orientationally disordered one. On the other hand, for sufficiently large values of z, we only find evidence of uniaxial calamitic behavior, as expected by following the limiting cases.
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Affiliation(s)
- Fulvio Bisi
- Dipartimento di Matematica "F. Casorati", Università di Pavia, via Ferrata 1, I-27100 Pavia, Italy
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Bisi F, De Matteis G, Romano S. Antinematic orientational order produced by an extreme case of the generalized Straley lattice model. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:020702. [PMID: 23005712 DOI: 10.1103/physreve.86.020702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Indexed: 06/01/2023]
Abstract
We address here a special, extreme case of the quadratic pair interaction potential between classical, D(2h)-symmetric particles (the generalized Straley model) on a three-dimensional simple cubic lattice. The model involves predominant antinematic couplings and it has been studied by Monte Carlo simulation and a molecular field treatment. The obtained results show a second-order transition between the isotropic phase and the low-temperature one, exhibiting uniaxial antinematic order.
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Affiliation(s)
- Fulvio Bisi
- Dipartimento di Matematica F Casorati, Università di Pavia, via Ferrata 1, I-27100 Pavia, Italy
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De Matteis G, Graudenzi A, Antoniotti M. A review of spatial computational models for multi-cellular systems, with regard to intestinal crypts and colorectal cancer development. J Math Biol 2012. [PMID: 22565629 DOI: 10.1007/s00285‐012‐0539‐4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Colon rectal cancers (CRC) are the result of sequences of mutations which lead the intestinal tissue to develop in a carcinoma following a "progression" of observable phenotypes. The actual modeling and simulation of the key biological structures involved in this process is of interest to biologists and physicians and, at the same time, it poses significant challenges from the mathematics and computer science viewpoints. In this report we give an overview of some mathematical models for cell sorting (a basic phenomenon that underlies several dynamical processes in an organism), intestinal crypt dynamics and related problems and open questions. In particular, major attention is devoted to the survey of so-called in-lattice (or grid) models and off-lattice (off-grid) models. The current work is the groundwork for future research on semi-automated hypotheses formation and testing about the behavior of the various actors taking part in the adenoma-carcinoma progression, from regulatory processes to cell-cell signaling pathways.
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Affiliation(s)
- Giovanni De Matteis
- Department of Mathematics "F. Enriques", University of Milan, Via Saldini 50, 20133 Milan, Italy
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Romano S, De Matteis G. Orientationally ordered phase produced by fully antinematic interactions: a simulation study. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:011703. [PMID: 21867192 DOI: 10.1103/physreve.84.011703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 04/22/2011] [Indexed: 05/31/2023]
Abstract
We consider here a classical model, consisting of D(2h) symmetric particles, whose centers of mass are associated with a three-dimensional simple-cubic lattice; the pair potential is isotropic in orientation space, and restricted to nearest neighbors. Two orthonormal triads define orientations of a pair of interacting particles; the simplest potential models proposed in the literature can be written as a linear combination involving the squares of the scalar products between corresponding unit vectors only, thus depending on three parameters, and making the interaction model rather versatile. A coupling constant with negative sign tends to keep the two interacting unit vectors parallel to each other, whereas a positive sign tends to keep them mutually orthogonal (antinematic coupling). We address here a special, extreme case of the above family, involving only antinematic couplings: more precisely, three antinematic terms whose coefficients are set to a common positive value (hence the name PPP model). The model under investigation produces a doubly degenerate pair ground state; the nearest-neighbor range of the interaction and the bipartite character of the lattice can propagate the pair ground state and increase the overall degeneracy, but without producing frustration. The model was investigated by a simplified molecular field treatment as well as by Monte Carlo simulation, whose results suggested a second-order transition to a low-temperature biaxially ordered phase; ground-state configurations producing orientational order have been selected by thermal fluctuations. The molecular field treatment also predicted a continuous transition, and was found to overestimate the transition temperature by a factor 2.
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Affiliation(s)
- Silvano Romano
- Dipartimento di Fisica A Volta, Università di Pavia, Via A Bassi 6, I-27100 Pavia, Italy.
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Abstract
We extended the analysis of a variational theory for nematoacoustics recently proposed by Virga [Phys. Rev. E 80, 031705 (2009)] by allowing the nematic director to vibrate about an average orientation at the frequency of a propagating wave, a periodic motion that we call the director libration. The acoustic susceptibilities, two phenomenological parameters that, in this theory, express the coupling between director and acoustic fields, are estimated along with an extra viscosity coefficient by using available experimental data.
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De Matteis G, Romano S. Mesogenic lattice models with partly antinematic interactions producing uniaxial nematic phases. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:031702. [PMID: 19905126 DOI: 10.1103/physreve.80.031702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Indexed: 05/28/2023]
Abstract
The present paper considers nematogenic lattice models, involving particles of D_{2h} symmetry, whose centers of mass are associated with a three-dimensional simple cubic lattice; the pair potential is isotropic in orientation space and restricted to nearest neighbors. Let two orthonormal triads define orientations of a pair of interacting particles; the simplest potential models proposed in the literature can be reduced to a linear combination involving the squares of the scalar products between corresponding unit vectors only and depending on three parameters. By now, various sets of potential parameters have been proposed and studied in the literature, some of which capable of producing biaxial orientational order at sufficiently low temperature. On the other hand, in experimental terms, mesogenic biaxial molecules mostly produce uniaxial mesophases; thus we address here two very simple cases, involving a nematic (calamitic) term as well as one (model P0M) or two (model PPM) antinematic ones, whose coefficients are set equal in magnitude; when only one antinematic coefficient is used, the third one is set to zero. The calamitic term favors the alignment of two corresponding molecular axes, whereas antinematic terms or geometric constraints tend to keep two other pairs of axes mutually orthogonal. The models were investigated by molecular-field treatments and Monte Carlo simulation and found to predict a first- or second-order transitions between uniaxial nematic and isotropic phases; the molecular-field treatments yielded results in reasonable agreement with simulation.
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Affiliation(s)
- Giovanni De Matteis
- Centro di Ricerca Matematica Ennio De Giorgi, Collegio Puteano, Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 3, I-56100 Pisa, Italy.
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De Matteis G, Romano S. Biaxial and uniaxial phases produced by partly repulsive mesogenic models involving D2h molecular symmetries. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 78:021702. [PMID: 18850847 DOI: 10.1103/physreve.78.021702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 04/22/2008] [Indexed: 05/26/2023]
Abstract
The present paper considers biaxial nematogenic lattice models, involving particles of D2h symmetry, whose centers of mass are associated with a three-dimensional simple-cubic lattice. The pair potential is isotropic in orientation space and restricted to nearest neighbors. Let two orthonormal triads define orientations of a pair of interacting particles. The investigated potential models are quadratic with respect to the nine scalar products between the two sets of unit vectors. Actually, based on available geometric identities, these expressions can be reduced to diagonal form containing only the scalar products between corresponding unit vectors and depending on three parameters. Over the years, this comparatively simple functional form has also proven to be rather versatile. By now, various sets of potential parameters capable of producing mesogenic behavior of some kind have been proposed and studied in the literature. A new and simplified form was recently proposed and investigated by Sonnet, Virga, Durand, and De Matteis [A. M. Sonnet, E. G. Virga, and G. E. Durand, Phys. Rev. E 67, 061701 (2003); G. De Matteis and E. G. Virga, Phys. Rev. E 71, 061703 (2005)] and is known to support a biaxial phase at sufficiently low temperature. Following the idea of the above authors, we have studied a more extended range of parameters, including cases where biaxiality cannot be sustained in the pair ground state. In cases where a biaxial phase survives, an appropriate mean-field analysis may predict the existence of a direct second-order transition to the isotropic phase as well as a second-order sequence isotropic-to-uniaxial-to-biaxial. A second-order phase transition is also predicted, which involves isotropic and uniaxial phases only. Monte Carlo simulations have been carried out as well, for a few points in the parameter space, and found to produce results which partly confirm mean-field predictions.
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Affiliation(s)
- Giovanni De Matteis
- Centro di Ricerca Matematica Ennio De Giorgi, Collegio Puteano, Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 3, I-56100 Pisa, Italy.
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Bisi F, Virga EG, Gartland EC, De Matteis G, Sonnet AM, Durand GE. Universal mean-field phase diagram for biaxial nematics obtained from a minimax principle. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:051709. [PMID: 16802956 DOI: 10.1103/physreve.73.051709] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 01/13/2006] [Indexed: 05/10/2023]
Abstract
We study a class of quadratic Hamiltonians which describe both fully attractive and partly repulsive molecular interactions, characteristic of biaxial liquid crystal molecules. To treat the partly repulsive interactions we establish a minimax principle for the associated mean-field free energy. We show that the phase diagram described by Sonnet [Phys. Rev. E 67, 061701 (2003)] is universal. Our predictions are in good agreement with the recent observations on both V-shaped and tetrapodal molecules.
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Affiliation(s)
- Fulvio Bisi
- Dipartimento di Matematica and CNISM, Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy
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De Matteis G, Romano S, Virga EG. Bifurcation analysis and computer simulation of biaxial liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:041706. [PMID: 16383401 DOI: 10.1103/physreve.72.041706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2005] [Revised: 07/19/2005] [Indexed: 05/05/2023]
Abstract
We extend the analysis of a mean-field model for biaxial liquid crystals recently proposed by Sonnet et al. [Phys. Rev. E 67, 061701 (2003)]. In particular, we perform a bifurcation analysis of the equilibrium equations and derive the complete phase diagram. We show that two order parameters suffice to label all equilibrium phases, though they exhibit different bifurcation patterns. A Monte Carlo simulation study is performed as well, confirming qualitatively the predictions of this analysis.
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Affiliation(s)
- Giovanni De Matteis
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.
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De Matteis G, Virga EG. Tricritical points in biaxial liquid crystal phases. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 71:061703. [PMID: 16089748 DOI: 10.1103/physreve.71.061703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 02/22/2005] [Indexed: 05/03/2023]
Abstract
We further pursue the analysis of a mean-field model recently proposed by Sonnet [Phys. Rev. E 67, 061701 (2003)] to describe nematic biaxial phases. This model, which is based on a simplified version of Straley's pair potential, is characterized by the prediction of a tricritical point along the transition line between uniaxial and biaxial phases. We show that the same model predicts another tricritical point, but along the line of the direct isotropic-to-biaxial transition. Our prediction is quantitative, as it stems from an analytical criterion for tricriticality.
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Affiliation(s)
- Giovanni De Matteis
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.
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