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We explore the phase behaviour of aqueous solutions of the cetyltrimethyl ammonium chloride (CTAC) surfactant and in particular the transition from the micellar phase (L

A coarse-grained model comprising short- and long-range effective potentials, parametrized with the iterative Boltzmann inversion (IBI) method, is presented for capturing micelle formation in aqueous solutions of ionic surfactants using as a model system sodium dodecyl sulfate (SDS). In the coarse-grained (CG) model, each SDS molecule is represented as a sequence of four beads while each water molecule is modeled as a single bead. The proposed CG scheme involves ten potential energy functions: four of them describe bonded interactions and control the distribution functions of intramolecular degrees of freedom (bond lengths, valence angles, and dihedrals) along an SDS molecule while the other six account for intermolecular interactions between pairs of SDS and water beads and control the radial distribution functions. The nonbonded effective potentials between coarse-grained SDS molecules extend up to about 12 nm and capture structural and morphological features of the micellar solution both at short and long distances. The long-range component of these potentials, in particular, captures correlations between surfactant molecules belonging to different micelles and is essential to describe ordering associated with micelle formation. A new strategy is introduced for determining the effective potentials through IBI by using information (target distribution functions) extracted from independent atomistic simulations of a micellar reference system (a salt-free SDS solution at total surfactant concentration cT equal to 103 mM, temperature T equal to 300 K, and pressure P equal to 1 atm) obtained through a multiscale approach described in an earlier study. It employs several optimization steps for bonded and nonbonded interactions and a gradual parametrization of the short- and long-range components of the latter, followed by reparametrization of the bonded ones. The proposed CG model can reproduce remarkably accurately the microstructure and morphology of the reference system within only a few hours of computational time. It is therefore very promising for future studies of structural and morphological behavior of various liquid surfactant formulations. ISSN:1520-6106 ISSN:1520-5207 ISSN:1089-5647

Hybrid mixtures composed of magnetic nanoparticles (MNP) in liquid crystalline (LC) matrices are a fascinating class of soft materials with intriguing physical properties and a wide range of potential applications, e.g., as stimuli-responsive and adaptive materials. Already in the absence of an external stimulus, these systems can display various types of orientationally disordered and ordered phases, which are enriched by self-assembled structures formed by the MNPs. In the presence of external fields, one typically observes highly nonlinear macroscopic behavior. However, an understanding of the structure and dynamics of such systems on the particle level has, so far, remained elusive. In the present paper we review recent computer simulation studies targeting the structure, equilibrium dynamics and rheology of LC-MNP systems, in which the particle sizes of the two components are comparable. As a numerically tractable model system we consider mixtures of soft spherical or elongated particles with a permanent magnetic dipole moment and ellipsoidal non-magnetic particles interacting via a Gay-Berne potential. We address, first, equilibrium aspects such as structural organization and self-assembly (cluster formation) of the MNPs in dependence of the orientational state of the matrix, the role of the size ratio, the impact of an external magnetic field, and the translational and orientational diffusion of the two components. Second, we discuss the non-equilibrium dynamics of LC-MNP mixtures under planar shear flow, considering both, spherical and non-spherical MNPs. Our results contribute to a detailed understanding of these intriguing hybrid materials, and they may serve as a guide for future experiments.

We address the problem of the quantitative prediction of micelle formation in dilute aqueous solutions of ionic surfactants using sodium dodecyl sulfate (SDS) as a model system through a computational approach that involves three steps: (a) execution of coarse-grained simulations based on the MARTINI force field (with slightly modified parameters to afford the formation of large micelles); (b) reverse mapping of the final self-assembled coarse-grained configuration into an all-atom configuration; and (c) final relaxation of this all-atom configuration through short-time (on the order of a few tens of nanoseconds), detailed isothermal-isobaric molecular dynamics simulations using the CHARMM36 force field. For a given concentration of the solution in SDS molecules, the modified MARTINI-based coarse-grained simulations lead to the formation of large micelles characterized by mean aggregation numbers above the experimentally observed ones. However, by reintroducing the detailed chemical structure through a strategy that solves a well-defined geometric problem and re-equilibrating, these large micellar aggregates quickly dissolve to smaller ones and equilibrate to sizes that perfectly match the average micelle size measured experimentally at the given surfactant concentration. From the all-atom molecular dynamics simulations, we also deduce the surfactant diffusivity DSDS and the zero-shear rate viscosity, η0, of the solution, which are observed to compare very favorably with the few experimental values that we were able to find in the literature.

In a recent contribution, we introduced a new approach for the quantitative prediction of the micellar morphology of aqueous solutions of ionic surfactants based on coarse-grained MARTINI-type simulations followed by reverse-mapped all-atom (AA) molecular dynamics (MD) ones, using as a model system sodium dodecyl sulfate. We make use of the same approach in the present work to study the micellar structure of aqueous solutions of sodium lauryl ether sulfate (SLEnS) with the chemical structure CH3(CH2)11(OCH2CH2)nOSO3Na with a fixed number n of ethoxyl (EO) groups per surfactant molecule (n = 1, 2, 3). These surfactants are used in a wide range of industrial applications, particularly in personal and home care products, but a quick literature survey proves that a systematic study of their microstructure, micellar morphology, and equilibrium transport properties is missing. Our simulations provide predictions for the mean aggregation number of such monodisperse SLEnS solutions which are found to be in very good agreement with experimental data already reported in the literature. They also show that for a given total surfactant concentration, SLEnS molecules with a smaller number n of EO groups form, on average, larger micelles. From the reverse-mapped AA MD simulations we also compute the zero shear rate viscosity of the solution whose value is found to increase as its total concentration in SLEnS molecules increases (for a given n) or as the number n of EO groups in the surfactant increases (for a given concentration)., JPhys Materials, 4 (4)

Despite that α-unsubstituted oligo-thiophenes (α-nTs) have been synthesized a long time ago and studied for many years, their phase behavior (which governs electronic performance, and thus their application in thin-film transistors) is still not fully understood. Here, we employ molecular dynamics simulations to study the high-temperature phase behaviour of α-nTs with n = 5–8 as a function of their molecular length using a recently proposed fully-flexible, united-atom model. We follow a methodology already developed for simulating the liquid-crystalline behaviour of α-sexithiophene, which we extend here to three other members of the family of α-nTs characterized by n = 5 (α-quinquethiophene), n = 7 (α-septithiophene) and n = 8 (α-octamer). Upon cooling fully pre-equilibrated bulk structures of these molecules from their amorphous, isotropic (Iso) phase at a high enough temperature down to lower temperatures, successive spontaneous phase transitions are observed leading to liquid crystalline phases. For n > 5, we observe first the formation of a nematic (Nem) phase and then the formation of two different types of smectic (Sm) phases. For n = 5, on the other hand, only one type of smectic phase is observed (no Nem was detected). We find that the type of the Sm phase formed is determined by the parity of the molecule: odd-numbered α-nTs display an orthogonal smectic A (SmA) phase whereas even-numbered α-nTs display both SmA and smectic C (SmC) phases, demonstrating a unique odd–even effect for these systems. In the SmC phase, the direction of the tilt angle is uniform, characteristic of a synclinic structure. The odd–even effect is also evident in the simulated crystalline phases of the studied α-nTs but also in other properties such as the density and the tilt angle which are found to alternate between high and low values for even- and odd-numbered α-nTs, respectively. It is interpreted here in terms of intra-molecular configurational changes taking place at the phase transition points.

Using computer simulations we explore the equilibrium structure and response to external stimuli of complex magnetic hybrids consisting of magnetic particles in discotic liquid crystalline matrices. We show that the anisotropy of the liquid crystalline matrix (either in the nematic or in the columnar phase) promotes the collective orientational ordering of self-assembled magnetic particles. Upon applying an external homogeneous magnetic field in an otherwise isotropic state, the magnetic particles self-assemble into linear-rodlike-chains. At the same time structural changes occur in the matrix. The matrix transforms from an isotropic to a non-conventional anti-nematic state in which the symmetry axis of the discs is, on average, perpendicular to the magnetic field. In addition, a stable biaxial nematic state is found upon applying an external field to an otherwise uniaxial discotic nematic state. These observed morphologies constitute an appealing alternative to binary mixtures of rigid rod–disc system and indicate that non-trivial biaxial ordering can be obtained in the presence of a uniaxial external stimulus.

We examine the high-temperature phase behaviour of α-unsubstituted sexithiophene (α-6T) by means of Molecular Dynamics (MD) and Monte Carlo (MC) simulations using a recently developed state-of-the-art algorithm based on internal bridging moves. In the MD simulations, a realistic fully flexible united-atom model is used. In the MC simulations, a stiffer version of this united-atom model is implemented by restricting atoms on thiophene rings to remain strictly co-planar by employing holonomic constraints for all bond lengths and intra-ring bond bending angles; on the other hand, inter-ring torsion and bond bending angles are considered to be fully flexible subject to suitable potential energy functions. The MD simulations, which are started from the isotropic (Iso) phase at a relatively high temperature (above 700 K) and continued to lower temperatures under isobaric conditions using a very large simulation cell containing 8960 α-6T molecules, show four phase transitions: an isotropic-to-nematic (Iso-to-Nem) at 640 K, a nematic-to-smectic A (Nem-to-SmA) at 630 K, a smectic A-to-smectic C (SmA-to-SmC) at 620 K demonstrating smectic polymorphism, and a SmC-to-crystal-like (SmC-to-Cry) at 600 K. In the corresponding MC simulations, no Nem phase is observed; the system, as it is isobarically cooled down to lower temperatures from its Iso phase, undergoes directly a transition to a SmC phase at 690 K. This is attributed to the stiffer nature of the forcefield employed in these simulations. Both methods (MD and MC) shed light on the type and degree of molecular self-assembly, orientational and positional ordering as a function of temperature, and manifestation of liquid crystalline behaviour of α-6T. We provide a thorough characterization of structural ordering in all mesophases observed, in terms of several measures (radial correlation functions, orientational order parameters and X-ray diffraction patterns). According to the results, at the phase transition temperatures, drastic configurational changes take place driving α-6T molecules to positionally-ordered phases accompanied by self-assembly into characteristic layers which, in turn, are self-organized into macroscopic smectic phases. Our methodology opens up the way to exploring the rich phase behaviour and anisotropic ordering of the condensed phases of several longer (and perhaps more complex) thiophene-based polymers.

e18803 Background: Cancer Associated Thrombosis (CAT) is an increasing challenge for oncology patients since oncologists sometimes are reluctant to mitigate the risk with thromboprophylaxis. Active cancer patients while receiving chemotherapy have a 7fold risk of thrombosis compared with no cancer patients. Anticoagulation holds a prominent place in prevention of CAT usually with Low Molecular Weight Heparins (LMWHs). Methods: ACT4CAT is prospective observational study conducted by HeSMO across Greece, aiming to record the clinical practice of CAT prophylaxis in patients with solid tumors. Ambulatory, high thrombotic risk, active cancer patients who received thromboprophylaxis enrolled after signing informed consent. Results: Preliminary results collected from 18 oncology departments. From 431 enrolled patients 322 (65.4%) had completed the study. Tumor types included: lung 28.8%, gastrointestinal 39.8%, gynecological 7.0%, breast 4.4%, urological 7.0% and others 20%. Majority of patients (88.2%) received High-Risk for Thrombosis Chemotherapy Agents (HRTCAs) such as platinum agents (55.9%), antimetabolites (44.7%) and immunotherapy (12.6%). In 1st line were 62.1%, 2nd line 18.4%, adjuvant 8.9% and neoadjuvant 2.4%. The following table depicts: age, gender, metastatic disease, Khorana score ≥2 and HRTCAs. All patients received thromboprophylaxis for 5.3±3.6 months with: tinzaparin 90.8%, fondaparinux 5.5%, bemiparin 1.5%, enoxaparin 1.2%, apixaban 0.5% and rivaroxaban 0.5%. Intermediate doses received 70.9% of patients regardless clinical setting (1st, 2nd, adjuvant & neoadjuvant: 70.2%, 79.2%, 51.3% and 70.0% respectively, p = 0.0254), although intermediate doses were used more in metastatic stages (OR:2.4 95%CI: 1.4-4.2, p = 0.0028). Nine thrombotic events reported (2.1%, 95%CI: 1.1-3.9%), irrespective of clinical setting but with a trend towards prophylactic doses. Eleven grade 1 bleedings reported (2.6%, 95%CI: 1.4-4.5%), despite clinical setting or dose used. Conclusions: Thromboprophylaxis in ambulatory active cancer patients with high thrombotic risk is safe and effective. Oncologists are alerted about CAT negative influences in cancer patients’ prognosis. Apart from Khorana score, factors such as metastases, use of HRTCAs and drug-drug interactions influence the clinical decision of thromboprophylaxis in active cancer patients mainly with LMWHs and quite often with intermediate doses regardless clinical setting. Clinical trial information: NCT03909399. [Table: see text]

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. Implementing extensive molecular dynamics simulations we explore the organization of magnetic particle assemblies (clusters) in a uniaxial liquid crystalline matrix comprised of rodlike particles. The magnetic particles are modelled as soft dipolar spheres with diameter significantly smaller than the width of the rods. Depending on the dipolar strength coupling the magnetic particles arrange into headto- tail configurations forming various types of clusters including rings (closed loops) and chains. In turn, the liquid crystalline matrix induces long range orientational ordering to these structures and promotes their diffusion along the director of the phase. Different translational dynamics are exhibited as the liquid crystalline matrix transforms either from isotropic to nematic or from nematic to smectic state. This is caused due to different collective motion of the magnetic particles into various clusters in the anisotropic environments. Our results offer a physical insight for understanding both the structure and dynamics of magnetic particle assemblies in liquid crystalline matrices.

Relapsed urothelial cancer represents an unmet medical need. Vinflunine is a third-generation antimicrotubuline inhibitor and is currently the only approved drug for second-line treatment across the European Union. We conducted a retrospective analysis assessing the efficacy and safety of vinflunine in 71 Greek patients with relapsed urothelial cancer who were treated between 2005 and 2014. An overall 84% of our patients received vinflunine as second-line treatment, 77% had a performance status of Eastern Cooperative Oncology Group scale 0 or 1, and 30% had liver metastasis at the time of vinflunine administration. A median of four cycles of vinflunine were administered (range 1-16). The most common reported adverse events were constipation, fatigue, and anemia. Median progression-free survival was 6.2 months (95% confidence interval: 4.4-8.8) and overall survival was 11.9 months (95% confidence interval: 7.4-21). Two patients (3%) achieved a complete remission, seven a partial remission (10%), and 22 (31%) had stable disease according to an intention-to-treat analysis. Hemoglobin level less than 10 g/dl and Eastern Cooperative Oncology Group performance status greater than 1 were independent adverse prognostic factors. Stratification according to the Bellmunt risk model was also associated with progression-free survival and overall survival in our population. Vinflunine appears to be a safe and effective treatment modality for relapsed urothelial cancer. More effective therapies and more accurate prognostic algorithms should be sought.

e14135 Background: CAT is the 2nd leading cause of death in oncology patients and there is need for thrombosis management across the natural history of cancer because of its dynamic nature. Anticoagulant therapy is the cornerstone of prevention and treatment, since thrombosis interferes with cancer treatment, increases health care resource utilization, imposes emotional and economic burden. Methods: A prospective observational study conducted by HeSMO across Greece, aiming to record the clinical practice of CAT prophylaxis in patients with solid tumors. Ambulatory, high risk for thrombosis, active cancer patients who received thromboprophylaxis are enrolled after signing informed consent. Results: Preliminary results are collected from 17 oncology departments. From the 272 enrolled patients, 176 (64.7%) have completed second visit (3-4 cycles of anticancer treatment). Primary cancers included: lung 31.3%, pancreas 26.1%, colorectal 13.6%, gynecological cancers 10.2%, stomach 7.8%, bladder 6.3%, and others.75.6% of the patients had metastatic disease. 1/3 of the patients were smokers or ex-smokers, and 33% underwent surgery. Most of patients (65.9%) were at 1st line treatment and 17.6% at 2nd line. The vast majority (90.3%) were treated with High-Risk for Thrombosis Chemotherapy Agents (HRTCAs) such as cisplatin etc. Regarding Khorana score, 65.1% had ≥2. In particular, 86.7% of patients with Khorana score ≤1 received HRTCAs while 95.4% of patients with score = 2.All patients received thromboprophylaxis, specifically: 93.0% tinzaparin, 5.2% fondaparinux and 1.8% other (enoxaparin, bemiparin) with average duration 5.3±3.1 months. 67.1% of the patients received higher than standard prophylactic doses. 3 patients (1.7%) experienced thrombotic events (2 DVT and 1 PE). These 3 patients had metastases and were treated with HRTCAs. Five grade 1 bleeding events were reported (2.8%). Conclusions: Thromboprophylaxis of CAT is both safe and effective. Oncologists are alerted about CAT negative influences in cancer patients’ prognosis. Apart from Khorana score, factors such as metastases, use of HRTCAs along with drug-drug interactions, increase the LMWHs usage often in higher than prophylactic doses in CAT management. Clinical trial information: NCT03909399.

Radical cystectomy is the treatment of choice in localized muscle-invasive urothelial cancer. Nevertheless, relapses are frequent and systemic chemotherapy has been employed in order to reduce this risk. In addition, bladder preservation strategies are appealing. During the last decade, there has been a difficulty in conducting and completing large-scale trials in urothelial cancer. This has resulted in relatively few changes in the existing guidelines. Recent studies have created renewed interest in certain fields, such as the role of chemo-radiotherapy and management of unfit patients. In addition, application of certain guidelines has been limited in everyday practice. We conducted a systematic review of the existing guidelines and recent randomized trials not included in these guidelines, and developed a treatment algorithm, regarding non-surgical therapies for non-metastatic, muscle-invasive urothelial cancer based predominantly on patients’ fitness for the available therapeutic modalities.

We study theoretically the optical properties of a two-dimensional lattice of metallic (gold) nanorods immersed within a nematic liquid crystal (NLC) strongly anchored to the surface of the nanorods. The distribution of the director field of the NLC is found by minimising the corresponding total free energy via simulated annealing. Optical properties such as transmittance, reflectance and absorbance of the structure are found by employing a hybrid discrete-dipole approximation/layer-multiple-scattering technique. We show, in particular, that when the NLC is strongly anchored to the nanorods, light absorbance is more efficient compared to the case where the liquid crystal (LC) is aligned by application of an external field. Also, the alignment of the LC molecules via an external field leads to a significant shift of the surface-plasmon resonance of the gold nanorods relative to the strong-anchoring case, an effect which can be exploited in switching applications. We also report that the rate of light absor...

Using experiments and molecular dynamics simulations, we explore magnetic field-induced phase transformations in suspensions of nonmagnetic rodlike and magnetic sphere-shaped particles. We experimentally demonstrate that an external uniform magnetic field causes the formation of small, stable clusters of magnetic particles that, in turn, induce and control the orientational order of the nonmagnetic subphase. Optical birefringence was studied as a function of the magnetic field and the volume fractions of each particle type. Steric transfer of the orientational order was investigated by molecular dynamics (MD) simulations; the results are in qualitative agreement with the experimental observations. By reproducing the general experimental trends, the MD simulation offers a cohesive bottom-up interpretation of the physical behavior of such systems, and it can also be regarded as a guide for further experimental research.

Background: State health insurance authorities in Greece do not reimburse genetic testing for cancer predisposition. The Hellenic Society of Medical Oncology has launched and carries out a national program covering genetic testing for BRCA1/2 mutations detection, with the financial support of pharmaceutical industry. Aim: This analysis evaluates how, during this program, access to genetic testing transformed the oncologists' therapeutic approach toward their ovarian cancer patients and how the results impacted treatment decisions concerning PARP inhibitors. Adoption of testing by healthy relatives and timing of testing in the disease continuum were also evaluated. Methods: Adult patients with high-grade epithelial ovarian carcinoma, irrespectively of family history or age at diagnosis were eligible for this program. Genetic counseling was recommended before testing, and both were offered at no financial cost. First degree family members of pathogenic mutation carriers were also offered free counseling and testing. Results: From March 2015 through January 2018, 708 patients were enrolled and tested. One hundred and forty seven (20.7%) mutation carriers were identified, 102 (14.4%) in BRCA1 and 45 (6.3%) in BRCA2 gene. Testing was more often pursued at initial diagnosis (61%) than at recurrence (39%), as recorded for 409 patients with available relevant information. During the 1st year of the program, average monthly tests performed were 25.1, while during the 3rd year this number increased to 34.3 tests per month. Among patients who tested positive for deleterious BRCA1/2 mutations, relapse was reported in 58 patients, 94.8% of which (n= 55) received treatment with the PARP inhibitor olaparib as per its indication. Family members of 21 patients (14.3%), out of the 147 who tested positive, received genetic counseling and testing for the mutation identified in the context of the program. Conclusion: Free access to genetic testing for BRCA1/2 for ovarian cancer patients and genetic consultation facilitates testing uptake, affects common clinical practice & has major impact on patients and their families. Still, diffusion of genetic information and broader testing of family members require further efforts by the oncological community.

We study the symmetry and the spatial uniformity of orientational order of the biaxial nematic phase in the light of recent experimental observations of phase biaxiality in thermotropic bent-core and calamitic-tetramer nematics. We present evidence supporting monoclinic symmetry, instead of the usually assumed orthorhombic. We describe the use of deuterium NMR to differentiate between the possible symmetries. We present the spatial aspects of biaxial order in the context of the cluster model, wherein macroscopic biaxiality can result from the field-induced alignment of biaxial and possibly polar domains. We discuss the implications of different symmetries, in conjunction with the microdomain structure of the biaxial phase, on the alignment of biaxial nematics and on the measurements of biaxial order., Comment: 15 pages 7 figures

Background Advanced urothelial cancer (AUCa) is associated with poor long-term survival. Two major concerns are related to nonexposure to cisplatin-based chemotherapy and poor outcome after relapse. Our purpose was to record patterns of practice in AUCa in Greece, focusing on first-line treatment and management of relapsed disease. Methods Patients with AUCa treated from 2011 to 2013 were included in the analysis. Fitness for cisplatin was assessed by recently established criteria. Results Of 327 patients treated with first-line chemotherapy, 179 (55%) did not receive cisplatin. Criteria for unfitness for cisplatin were: Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≥ 2, 21%; creatinine clearance ≤ 60 mL/min, 55%; hearing impairment, 8%; neuropathy, 1%; and cardiac failure, 5%. Forty-six patients (27%) did not fulfill any criterion for unfitness for cisplatin. The main reasons for these deviations were comorbidities (28%) and advanced age (32%). Seventy-four (68%) of 109 patients who experienced a relapse received second-line chemotherapy. The most frequent reason for not offering second-line chemotherapy was poor PS or limited life expectancy (66%). Conclusion In line with international data, approximately 50% of Greek patients with AUCa do not receive cisplatin-based chemotherapy, although 27% of them were suitable for such treatment. In addition, about one third of patients with relapse did not receive second-line chemotherapy because of poor PS or short life expectancy. Enforcing criteria for fitness for cisplatin and earlier diagnosis of relapse represent 2 targets for improvement in current treatment practice for AUCa.

Using Monte Carlo computer simulations we explore the self-assembly and ordering behavior of a hybrid, soft magnetic system consisting of small magnetic nanospheres in a liquid-crystalline (LC) matrix. Inspired by recent experiments with colloidal rod matrices, we focus on conditions where the sphere and rod diameters are comparable. Already in the absence of a magnetic field, the nematic ordering of the LC can stabilize the formation of magnetic chains along the nematic or smectic director, yielding a state with local (yet no macroscopic) magnetic order. The chains, in turn, increase the overall nematic order, reflecting the complex interplay of the structure formation of the two components. When increasing the sphere diameter, the spontaneous uniaxial ordering is replaced by biaxial lamellar morphologies characterized by alternating layers of rods and magnetic chains oriented perpendicular to the rod's director. These ordering scenarios at zero field suggest a complex response of the resulting hybrid to external stimuli, such as magnetic fields and shear forces.

We investigate the self-organization of a binary mixture of similar sized rods and dipolar soft spheres by means of Monte-Carlo simulations. We model the interparticle interactions by employing anisotropic Gay-Berne, dipolar and soft-sphere interactions. In the limit of vanishing magnetic moments we obtain a variety of fully miscible liquid crystalline phases including nematic, smectic and lamellar phases. For the magnetic mixture, we find that the liquid crystalline matrix supports the formation of orientationally ordered ferromagnetic chains. Depending on the relative size of the species the chains align parallel or perpendicular to the director of the rods forming uniaxial or biaxial nematic, smectic and lamellar phases. As an exemplary external perturbation we apply a homogeneous magnetic field causing uniaxial or biaxial ordering to an otherwise isotropic state., 11 pages, 12 figures

We explore the phase behavior and structure of orthogonal smectic liquid crystals consisting of bent-core molecules (BCMs) by means of Monte Carlo molecular simulations. A simple athermal molecular model is introduced that describes the basic features of the BCMs. Phase transitions between uniaxial and biaxial (antiferroelectric) orthogonal smectics are obtained. The results indicate the presence of local in-plane polar correlations in the uniaxial smectic phase. The macroscopic uniaxial-biaxial transformation is rationalized in terms of local polar correlations giving rise to polar domains. The size of these polar domains grows larger under the action of an external vector field and their internal ordering is enhanced, leading to field-induced biaxial order-disorder transitions., 7 pages, 8 figures

The phase behavior of amphiphilic anisometric particles is explored using Monte Carlo simulations. The particles are composed of two incompatible laterally attached units: a spherocylinder and a spheroplatelet. A liquid crystalline phase polymorphism is obtained including biaxial nematic, (quasi long range biaxial) calamitic smectic-A, biaxial lamellar and columnar phases. The simulation results demonstrate intriguing phase transitions such as nematic–nematic, discotic nematic to (quasi long range biaxial) calamitic smectic-A, biaxial nematic to uniaxial calamitic smectic-A, and isotropic or discotic nematic to biaxial lamellar phases that possess nematic ordering within the layers. These findings are rationalized in terms of molecular geometry and amphiphilicity of different molecular units. The molecular model can be used as a tool for the prediction of the complex phase behavior that is relevant to liquid crystalline colloids.

The phase behavior of hard boardlike biaxial particles of relative dimensions close to the clamitic to discotic crossover is explored by means of Monte Carlo molecular simulations. Transitions between two distinct biaxial nematic phases as well as transitions from a biaxial nematic to a uniaxial Sm-$A$ phase are obtained. The formation of anisotropic supramolecular assemblies is demonstrated and is quantified by means of rotationally invariant pair correlation functions.

The rich mesophase polymorhism and the phase sequence of board-like colloids depends critically on their shape anisometry. Implementing extensive Monte Carlo simulations, we calculated the full phase diagram of sterically interacting board-like particles, for a range of experimentally accessible molecular dimensions/anisometries of colloids of this shape. A variety of self organized mesophases including uniaxial and biaxial nematics, smectic, cubatic and columnar phases have been identified. Our results demonstrate clearly that the molecular anisometry influences critically not only the structure and the symmetry of the mesophases but also, and perhaps more interestingly, the phase sequence among them. New classes of phase sequences such as nematic-nematic and, for the first time, a direct transition from a discotic and a biaxial nematic to an orthogonal smectic A phase have been identified. The molecular geometry requirements for such a phase behavior have been located., Comment: 10 pages, 3 figures

We study theoretically the magneto-optical properties of suspensions of magnetic nanoparticles within liquid crystalline matrices whose structure has been explored using off-lattice canonical Monte Carlo simulations. We find, in particular, that such systems exhibit a very strong magnetic circular-dichroism signal generated by morphological transformations of the structural motives of magnetic nanoparticles. These occur when the liquid crystalline matrix passes from isotropic to nematic states upon application of an external magnetic field. Moreover, we find that such hybrid magnetic-nanoparticle/liquid-crystalline systems demonstrate strong Faraday effect in the visible regime.

8561Background: Pazopanib (PZB) is a small anti-angiogenic molecule inhibiting the tyrosine kinase of VEGFR-1, VEGFR-2, VEGFR-3, PDGF, and c-kit. Several studies have shown that angiogenesis is of ...

The structure of nematic liquid crystals formed by bent-core mesogens (BCMs) is studied in the context of Monte Carlo simulations of a simple molecular model that captures the symmetry, shape, and flexibility of achiral BCMs. The results indicate the formation of (i) clusters exhibiting local smectic order, orthogonal or tilted, with strong in-layer polar correlations and antiferroelectric juxtaposition of successive layers and (ii) large homochiral domains through the helical arrangement of the tilted smectic clusters, while the orthogonal clusters produce achiral (untwisted) nematic states.

A theoretical model of shape-anisometric particles embedded in a cubic lattice is formulated for binary mixtures combining rod-like, plate-like and spherical particles. The model aims at providing a tool for the prediction and interpretation of complex phase behavior in a variety of liquid crystalline colloids, biological and macromolecular systems. Introducing just repulsive interactions among the particles, a rich variety of phase structures and multiphasic equilibria is obtained, including isotropic, nematic, lamellar and columnar phases, demixing into phases of the same or different symmetries and structural microsegregation of the different species of the mixture within the same phase.

The molecular cubic-block model [ J. Chem. Phys. 2005, 123, 164904 ] is used to study a class of poly(benzyl ether) fullerodendrimers that have recently been reported to form columnar liquid crystal phases. In agreement with experiment, the model-molecules are found to self-assemble into columns which form hexagonal or rectangular lattices. The columnar cross sections are elongated in the rectangular phase. Transitions to the isotropic phase, either directly or through the intermediate formation of smectic phases, have been found. The effects of dissolving small amounts of nonbonded fullerene molecules have been explored. The results predict that the fullerene solutes restrict the range of stability of the columnar phase and may induce transitions from the columnar to the smectic or the isotropic phase.

Systematic efforts to synthesise fullerene containing LCs have produced a variety of successful model compounds. We present a simple molecular theory relating the self-organisation observed in these systems to their molecular structure. The interactions are modelled by dividing each molecule into a number of sub-molecular blocks to which specific interactions are assigned. Three types of blocks are introduced, corresponding to fullerene units, mesogenic units, and non-mesogenic linkage units. The blocks are constrained to move on a rectangular 3-dimensional lattice and molecular flexibility is allowed by retaining a number of representative conformations within the block representation of the molecule. Calculations are presented for a variety of molecular architectures including twin mesogenic branch mono-adducts of C60, twin dendro-mesogenic branch mono-adducts and conical (badminton shuttlecock) multi-adducts of C60. In spite of its many simplifications, the theory accounts remarkably well for the phase behaviour of these systems., 22 pages, 9 figures

e15514 Background: Cisplatin based chemotherapy is the tretment of choice in metastatic UC. Worldwide about 50% of patients do not receive this treatment. Available data on this issue are mising fo...

The association between inflammatory bowel disease and colorectal cancer is well known. Ulcerative colitis is a risk factor for the development of colorectal cancer, and this risk increases with the activity and duration of bowel inflammation. Here we describe the case of a 52-year-old man who developed ulcerative colitis 6 years after the diagnosis and treatment of colon cancer. Although this could be a coincidence, there could be additional possibilities, like pre-existence of quiescent colitis, late effect of therapy, or maybe the existence of common pathogenetic factors contributing to the development of ulcerative colitis and colorectal cancer.

A molecular model of cubic building blocks is used to describe the mesomorphism of conical fullerenomesogens. Calculations based on density functional molecular theory and on Monte Carlo computer simulations give qualitatively similar results that are also in good agreement with the experimentally observed mesomorphic behaviour. The columnar and lamellar mesophases obtained are non-polar, and their relative stability is controlled by a single model parameter representing the softness of the repulsive interactions among the building blocks of the conical molecules.