Eighth-order phase-field-crystal model for two-dimensional crystallization

We present a derivation of the recently proposed eighth order phase field crystal model [Jaatinen et al., Phys. Rev. E 80, 031602 (2009)] for the crystallization of a solid from an undercooled melt. The model is used to study the planar growth of a two dimensional hexagonal crystal, and the results are compared against similar results from dynamical density functional theory of Marconi and Tarazona, as well as other phase field crystal models. We find that among the phase field crystal models studied, the eighth order fitting scheme gives results in good agreement with the density functional theory for both static and dynamic properties, suggesting it is an accurate and computationally efficient approximation to the density functional theory

Diffusion-controlled anisotropic growth of stable and metastable crystal polymorphs in the phase-field crystal model

The official published version of the article can be accessed from the link below - Copyright @ 2009 APSWe use a simple density functional approach on a diffusional time scale, to address freezing to the body-centered cubic (bcc), hexagonal close-packed (hcp), and face-centered cubic (fcc) structures. We observe faceted equilibrium shapes and diffusion-controlled layerwise crystal growth consistent with two-dimensional nucleation. The predicted growth anisotropies are discussed in relation with results from experiment and atomistic simulations. We also demonstrate that varying the lattice constant of a simple cubic substrate, one can tune the epitaxially growing body-centered tetragonal structure between bcc and fcc, and observe a Mullins-Sekerka-Asaro-Tiller-Grinfeld-type instability.This work has been supported by the EU FP7 Collaborative Project ENSEMBLE under Grant Agreement NMP4-SL-2008-213669, the Hungarian Academy of Sciences under contract OTKA-K-62588, the Academy of Finland via its COMP CoE grant, and by Tekes via its MASIT33 project. A. J. acknowledges financial support from the Finnish Academy of Science and Letters. T. P. acknowledges support from the Bolyai Ja´nos Grant

Donor-specific HLA antibodies in predicting crossmatch outcome : Comparison of three different laboratory techniques

The virtual crossmatch, which is based on single antigen bead technology, is used in the prediction of crossmatch results. However, this assay differs in sensitivity and specificity from crossmatch methods. In our study, the results of physical crossmatches, performed with three different methods, were assessed against virtual cross match results. The aim was to determine the potential cut-off values for donor specific antibodies (DSA) that would predict the crossmatch results obtained by different methods. The results of different crossmatch techniques were correlated with the virtual crossmatch. The receiver operating characteristic (ROC) analysis revealed the Flow cytometric crossmatch (FCXM) and Luminex crossmatch (LXM) to be the most accurate, with area under curve (AUC) values of 0.861 and 0.805, respectively. While we found that the virtual crossmatch correlated well with all the crossmatch results, FCXM produced the best results (83% of the DSA detected). LXM outperformed the other tests in terms of the accuracy in separating class II DSA.Peer reviewe

Phase field crystal study of symmetric tilt grain boundaries of iron

We apply the phase field crystal model to study the structure and energy of symmetric tilt grain boundaries of bcc iron in 3D. The parameters for the model are obtained by using a recently developed eight-order fitting scheme [A. Jaatinen et al., (2009)]. The grain boundary free energies we obtain from the model are in good agreement with previous results from molecular dynamics simulations and experiments

Miten lääketieteen ja hoitotyön opiskelijat hahmottavat oman ja muiden ammattiryhmien roolin terveydenhuollon moniammatillisessa työkentässä

Poriin valmistui kesällä 2005 opetuskäyttöön suunniteltu opetusterveyskeskus. Ensimmäiset Turun yliopiston lääketieteen opiskelijat tulivat sinne elokuussa 2005. Marraskuusta 2005 alkaen myös Satakunnan ammattikorkeakoulun sairaanhoitaja – ja terveydenhoitajaopiskelijoita tuli opetusterveyskeskukseen käytännön harjoittelujaksolle. Tämä mahdollisti lääketieteen ja hoitotyön opiskelijoiden yhteisharjoittelun. Puolentoista vuoden ajan marraskuusta 2005 toukokuuhun 2007 opiskelijat täyttivät IEPS (Interdisciplinary Education Perception Scale) kyselylomakkeen. Lomakkeella selvitettiin miten lääketieteen ja hoitotyön opiskelijat hahmottavat oman ja muiden ammattiryhmien roolin terveydenhuollon moniammatillisessa työkentässä. Lomake käännettiin suomeksi ja tehtiin suomalaisiin olosuhteisin alkuperäistä paremmin soveltuva kysymysten ryhmittelyehdotus. Kummankin alan opiskelijat tiedostivat hyvin tarpeen tehdä yhteistyötä eri ammattiryhmien välillä ja että heidän on luotettava muiden ammattiryhmien työhön. Lääketieteen ja hoitotyön opiskelijoiden ajattelutavoissa oli vain pieniä eroja. Molemmat opiskelijaryhmät tiedostivat hyvin olevansa valmistumassa ammatteihin, joissa keskinäinen yhteistyö on välttämätöntä. Lääketieteen opiskelijat kokivat, että heidän ammattikuntansa status on muita korkeampi. Hoitotyön opiskelijat puolestaan kokivat lääketieteen opiskelijoitakin selvemmin, että heidän ammattikuntansa on äärimmäisen pätevää

Ammonium nitrate evaporation and nitric acid condensation in DMT CCN counters

The effect of inorganic semivolatile aerosol compounds on the cloud condensation nucleus (CCN) activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big a fraction of semivolatiles is evaporated from particles after entering but before particle activation in the DMT-CCN counter? (2) How much can the CCN activity be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? Both experimental and modelling results show that the evaporation of ammonia and nitric acid from ammonium nitrate particles causes a 10 to 15 nm decrease to the critical particle size in supersaturations between 0.1% and 0.7%. On the other hand, the modelling results also show that condensation of nitric acid or similar vapour can increase the CCN activity of nonvolatile aerosol particles, but a very high gas phase concentration (as compared to typical ambient conditions) would be needed. Overall, it is more likely that the CCN activity of semivolatile aerosol is underestimated than overestimated in the measurements conducted in ambient conditions

Bcc crystal-fluid interfacial free energy in Yukawa systems

We determine the orientation-resolved interfacial free energy between a body-centered-cubic (bcc) crystal and the coexisting fluid for a many-particle system interacting via a Yukawa pair potential. For two different screening strengths, we compare results from molecular dynamics computer simulations, density functional theory, and a phase-field-crystal approach. Simulations predict an almost orientationally isotropic interfacial free energy of 0.12k B T/a 2 (with k B T denoting the thermal energy and a the mean interparticle spacing), which is independent of the screening strength. This value is in reasonable agreement with our Ramakrishnan-Yussouff density functional calculations, while a high-order fitted phase-field-crystal approach gives about 2−3 times higher interfacial free energies for the Yukawa system. Both field theory approaches also give a considerable anisotropy of the interfacial free energy. Our result implies that, in the Yukawa system, bcc crystal-fluid free energies are a factor of about 3 smaller than face-centered-cubic crystal-fluid free energies.Peer reviewe

Febuxostat, But Not Allopurinol, Markedly Raises the Plasma Concentrations of the Breast Cancer Resistance Protein Substrate Rosuvastatin

Xanthine oxidase inhibitors febuxostat and allopurinol are commonly used in the treatment of gout. Febuxostat inhibits the breast cancer resistance protein (BCRP) in vitro. Rosuvastatin is a BCRP substrate and genetic variability in BCRP markedly affects rosuvastatin pharmacokinetics. In this study, we investigated possible effects of febuxostat and allopurinol on rosuvastatin pharmacokinetics. In a randomized crossover study with 3 phases, 10 healthy volunteers ingested once daily placebo for 7 days, 300 mg allopurinol for 7 days, or placebo for 3 days, followed by 120 mg febuxostat for 4 days, and a single 10 mg dose of rosuvastatin on day 6. Febuxostat increased the peak plasma concentration and area under the plasma concentration-time curve of rosuvastatin 2.1-fold (90% confidence interval 1.8-2.6; P = 5 x 10(-5)) and 1.9-fold (1.5-2.5; P = 0.001), but had no effect on rosuvastatin half-life or renal clearance. Allopurinol, on the other hand, did not affect rosuvastatin pharmacokinetics. In vitro, febuxostat inhibited the ATP-dependent uptake of rosuvastatin into BCRP-overexpressing membrane vesicles with a half-maximal inhibitory concentration of 0.35 mu M, whereas allopurinol showed no inhibition with concentrations up to 200 mu M. Taken together, the results suggest that febuxostat increases rosuvastatin exposure by inhibiting its BCRP-mediated efflux in the small intestine. Febuxostat may, therefore, serve as a useful index inhibitor of BCRP in drug-drug interaction studies in humans. Moreover, concomitant use of febuxostat may increase the exposure to BCRP substrate drugs and, thus, the risk of dose-dependent adverse effects.Peer reviewe

Factors associated with and 1-year outcomes of fear of falling in a geriatric post-hip fracture assessment

Background: Hip fracture causes not only physical injury but also psychological trauma. Fear of falling (FoF) is related to poor recovery, loss of mobility and mortality. There is limited data on the clinical factors affecting post-hip fracture FoF and its consequences. Objective: To investigate the factors associated with and 1-year outcomes of post-hip fracture FoF. Methods: An observational prospective cohort study. Data were collected on hospital admission, at a geriatric outpatient assessment 4–6 months post-hip fracture and by telephone interviews 1 year after the index fracture. FoF was assessed with a dichotomous single-item question. Logistic regression analyses were conducted to examine the age, gender and multivariable-adjusted association between baseline and the geriatric assessment domains with FoF. Follow-up outcomes included changes in mobility, living arrangements and mortality. Results: Of the 916 patients included, 425 (49%) had FoF at the time of their geriatric assessment. These patients were predominantly female and were living alone in their own homes with supportive home care. They scored lower on tests of physical performance. Less FoF was documented in patients with diagnosed cognitive disorders before the index fracture and in those with Clinical Dementia Rating ≥ 1. After adjusting for age and gender, no association was observed between FoF and any of the 1-year follow-up outcomes. Conclusion: Post-hip fracture FoF is common and associated with female gender, polypharmacy, poor daily functioning, poor physical performance and depressive mood. Patients with cognitive disorders have less FoF than those without. FoF appears to have no impact on the follow-up outcomes.publishedVersionPeer reviewe