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1.
J Clin Psychol ; 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31825098

RESUMO

OBJECTIVE: We describe the development of an instrument aiming to offer interaction-level feedback based on "patient activation": client confidence and perceived ability to manage their health. METHOD: Twenty-two session-transcripts from cognitive behavioral therapy with high-users of healthcare were analyzed thematically, producing themes describing in-session interactions. Themes were subcategorized using patient activation theory into high and low activation presentations. Two coders new to the process were trained to use this consultation interactions coding scheme (CICS). Inter-rater reliability (IRR), convergent validity, and clinical utility were assessed and illustrated with extreme cases. RESULTS: Good-to-excellent IRR was achieved. The CICS, therapeutic alliance, and therapist competence were correlated. Client engagement in session-structuring interactions correlated with outcome. The highest CICS scorer showed multiple outcome-improvements, the lowest scorer reported deteriorations. CONCLUSIONS: This study presents the CICS's psychometric properties and indicates the value of client engagement in session-structuring.

2.
Psychother Res ; : 1-13, 2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31438807

RESUMO

Objective: Routine outcome monitoring (ROM) is a well-evidenced means of improving psychotherapy's effectiveness. However, it is unclear how meaningful ROM is for problems that span physical and mental health, such as severe health anxiety. Physical and mental health comorbidities are common amongst severe health anxiety sufferers and cognitive behavioral therapy (CBT) is a recommended treatment. Method: Seventy-nine participants received CBT for severe health anxiety in a clinical trial. The Outcome Rating Scale (ORS: a ROM assessment of wellbeing) was completed at each session. Multilevel modeling assessed whether last-session ORS predicted health anxiety and other outcomes over 12-month follow-up. Similar models were developed using health anxiety as a comparative outcome-predictor. Outcome-improvements of treatment-responders with sudden gains were compared to those of non-sudden-gainers. Results: Last-session ORS scores predicted all outcomes up to 12 months later, with a comparable predictive effect to health anxiety. Sudden-gainers on the ORS reported significantly greater improvement in depression, functioning, and wellbeing, but no difference in health anxiety or other measures. Conclusion: The ORS may be a feasible, overall estimate of health, functioning, and quality of life in psychotherapy for severe health anxiety. Sudden gains on the ORS may be clinically meaningful with respect to some long-term outcomes.

3.
Respir Res ; 20(1): 111, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170998

RESUMO

BACKGROUND: Tyrosine kinase inhibitors (TKIs) inhibit the platelet derived growth factor receptor (PDGFR) and gain increasing significance in the therapy of proliferative diseases, e.g. pulmonary arterial hypertension (PAH). Moreover, TKIs relax pulmonary vessels of rats and guinea pigs. So far, it is unknown, whether TKIs exert relaxation in human and murine pulmonary vessels. Thus, we studied the effects of TKIs and the PDGFR-agonist PDGF-BB in precision-cut lung slices (PCLS) from both species. METHODS: The vascular effects of imatinib (mice/human) or nilotinib (human) were studied in Endothelin-1 (ET-1) pre-constricted pulmonary arteries (PAs) or veins (PVs) by videomicroscopy. Baseline initial vessel area (IVA) was defined as 100%. With regard to TKI-induced relaxation, K+-channel activation was studied in human PAs (PCLS) and imatinib/nilotinib-related changes of cAMP and cGMP were analysed in human PAs/PVs (ELISA). Finally, the contractile potency of PDGF-BB was explored in PCLS (mice/human). RESULTS: Murine PCLS: Imatinib (10 µM) relaxed ET-1-pre-constricted PAs to 167% of IVA. Vice versa, 100 nM PDGF-BB contracted PAs to 60% of IVA and pre-treatment with imatinib or amlodipine prevented PDGF-BB-induced contraction. Murine PVs reacted only slightly to imatinib or PDGF-BB. Human PCLS: 100 µM imatinib or nilotinib relaxed ET-1-pre-constricted PAs to 166% or 145% of IVA, respectively, due to the activation of KATP-, BKCa2+- or Kv-channels. In PVs, imatinib exerted only slight relaxation and nilotinib had no effect. Imatinib and nilotinib increased cAMP in human PAs, but not in PVs. In addition, PDGF-BB contracted human PAs/PVs, which was prevented by imatinib. CONCLUSIONS: TKIs relax pre-constricted PAs/PVs from both, mice and humans. In human PAs, the activation of K+-channels and the generation of cAMP are relevant for TKI-induced relaxation. Vice versa, PDGF-BB contracts PAs/PVs (human/mice) due to PDGFR. In murine PAs, PDGF-BB-induced contraction depends on intracellular calcium. So, PDGFR regulates the tone of PAs/PVs. Since TKIs combine relaxant and antiproliferative effects, they may be promising in therapy of PAH.


Assuntos
Pulmão/irrigação sanguínea , Pulmão/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Artéria Pulmonar/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Feminino , Humanos , Pulmão/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Artéria Pulmonar/fisiologia , Especificidade da Espécie , Vasodilatação/fisiologia
4.
J Chem Phys ; 150(17): 174501, 2019 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-31067860

RESUMO

This paper determines the thermodynamic phase diagram of the EXP system of particles interacting by the purely repulsive exponential pair potential. The solid phase is face-centered cubic (fcc) at low densities and pressures. At higher densities and pressures, the solid phase is body-centered cubic (bcc) with a re-entrant liquid phase at the highest pressures simulated. The investigation first identifies the phase diagram at zero temperature at which the following four crystal structures are considered: fcc, bcc, hexagonal close packed, and cubic diamond. There is a T = 0 phase transition at pressure 2.651 × 10-3 with the thermodynamically stable structure being fcc below and bcc above this pressure. The densities of the two crystal structures at the phase transition are 1.7469 × 10-2 (fcc) and 1.7471 × 10-2 (bcc). At finite temperatures, the fcc-bcc, fcc-liquid, and bcc-liquid coexistence lines are determined by numerical integration of the Clausius-Clapeyron equation and validated by interface-pinning simulations at selected state points. The bcc-fcc phase transition is a weak first-order transition. The liquid-fcc-bcc triple point, which is determined by the interface-pinning method, has temperature 5.9 × 10-5 and pressure 2.5 × 10-6; the triple-point densities are 1.556 × 10-3 (liquid), 1.583 × 10-3 (bcc), and 1.587 × 10-3 (fcc).

5.
Sci Rep ; 9(1): 1902, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30760775

RESUMO

Argon exerts neuroprotection. Thus, it might improve patients' neurological outcome after cerebral disorders or cardiopulmonary resuscitation. However, limited data are available concerning its effect on pulmonary vessel and airways. We used rat isolated perfused lungs (IPL) and precision-cut lung slices (PCLS) of rats and humans to assess this topic. IPL: Airway and perfusion parameters, oedema formation and the pulmonary capillary pressure (Pcap) were measured and the precapillary and postcapillary resistance (Rpost) was calculated. In IPLs and PCLS, the pulmonary vessel tone was enhanced with ET-1 or remained unchanged. IPLs were ventilated and PCLS were gassed with argon-mixture or room-air. IPL: Argon reduced the ET-1-induced increase of Pcap, Rpost and oedema formation (p < 0.05). PCLS (rat): Argon relaxed naïve pulmonary arteries (PAs) (p < 0.05). PCLS (rat/human): Argon attenuated the ET-1-induced contraction in PAs (p < 0.05). Inhibition of GABAB-receptors abolished argon-induced relaxation (p < 0.05) in naïve or ET-1-pre-contracted PAs; whereas inhibition of GABAA-receptors only affected ET-1-pre-contracted PAs (p < 0.01). GABAA/B-receptor agonists attenuated ET-1-induced contraction in PAs and baclofen (GABAB-agonist) even in pulmonary veins (p < 0.001). PLCS (rat): Argon did not affect the airways. Finally, argon decreases the pulmonary vessel tone by activation of GABA-receptors. Hence, argon might be applicable in patients with pulmonary hypertension and right ventricular failure.

6.
J Chem Phys ; 150(2): 021101, 2019 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30646717

RESUMO

We present diffusion coefficient and shear viscosity data for the Lennard-Jones fluid along nine isochores above the critical density, each involving a temperature variation of roughly two orders of magnitude. The data are analyzed with respect to the Stokes-Einstein (SE) relation, which breaks down gradually at high temperatures. This is rationalized in terms of the fact that the reduced diffusion coefficient D ̃ and the reduced viscosity η ̃ are both constant along the system's lines of constant excess entropy (the isomorphs). As a consequence, D ̃ η ̃ is a function of T/T Ref(ρ) in which T is the temperature, ρ is the density, and T Ref(ρ) is the temperature as a function of the density along a reference isomorph. This allows one to successfully predict the viscosity from the diffusion coefficient in the studied region of the thermodynamic phase diagram.

7.
Psychol Psychother ; 92(4): 584-604, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-30390362

RESUMO

PURPOSE: To review and synthesize the qualitative literature on service users' experiences of endings from a psychological service or therapy. METHODS: A systematic search of the peer-reviewed literature identified qualitative studies meeting specific inclusion criteria. A modified CASP tool was used to critically appraise their quality, and a meta-ethnographic approach was used to synthesize their findings. RESULTS: Twelve papers met the inclusion criteria. The interpretation of findings suggested three key themes: anticipation of ending, service user control, and sense of responsibility. Although studies varied in geographical location and type of service, they were consistently of high quality. CONCLUSIONS: The review highlights the importance of service users' perspectives in understanding the experiences of endings. The findings complement existing literature and provide new interpretations. Considerations for practice were limited; however, the review provides useful directions for future research. PRACTITIONER POINTS: When ending therapy, clinicians should consider the dyadic nature of the therapeutic relationship and the emotional impact this may have upon both service users and staff. Further consideration should be given to how staff manage their responses to the ending. The time-limited structure of therapy may aid the ending process by relieving staff and service users of responsibility.

8.
J Chem Phys ; 149(11): 114502, 2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30243289

RESUMO

This paper continues the investigation of the exponentially repulsive EXP pair-potential system of Paper I [A. K. Bacher et al., J. Chem. Phys. 149, 114501 (2018)] with a focus on isomorphs in the low-temperature gas and liquid phases. As expected from the EXP system's strong virial potential-energy correlations, the reduced-unit structure and dynamics are isomorph invariant to a good approximation. Three methods for generating isomorphs are compared: the small-step method that is exact in the limit of small density changes and two versions of the direct-isomorph-check method that allows for much larger density changes. Results from the latter two approximate methods are compared to those of the small-step method for each of the three isomorphs generated by 230 one percent density changes, covering one decade of density variation. Both approximate methods work well.

9.
J Chem Phys ; 149(11): 114501, 2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30243291

RESUMO

It was recently shown that the exponentially repulsive EXP pair potential defines a system of particles in terms of which simple liquids' quasiuniversality may be explained [A. K. Bacher et al., Nat. Commun. 5, 5424 (2014); J. C. Dyre, J. Phys.: Condens. Matter 28, 323001 (2016)]. This paper and its companion [A. K. Bacher et al., J. Chem. Phys. 149, 114502 (2018)] present a detailed simulation study of the EXP system. Here we study how structure monitored by the radial distribution function and dynamics monitored by the mean-square displacement as a function of time evolve along the system's isotherms and isochores. The focus is on the gas and liquid phases, which are distinguished pragmatically by the absence or presence of a minimum in the radial distribution function above its first maximum. A constant-potential-energy (NVU)-based proof of quasiuniversality is presented, and quasiuniversality is illustrated by showing that the structure of the Lennard-Jones system at four state points is well approximated by those of EXP pair-potential systems with the same reduced diffusion constant. Paper II studies the EXP system's isomorphs, focusing also on the gas and liquid phases.

10.
Adv Sci (Weinh) ; 5(6): 1700955, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29938172

RESUMO

Growth and characterization of advanced group IV semiconductor materials with CMOS-compatible applications are demonstrated, both in photonics. The investigated GeSn/SiGeSn heterostructures combine direct bandgap GeSn active layers with indirect gap ternary SiGeSn claddings, a design proven its worth already decades ago in the III-V material system. Different types of double heterostructures and multi-quantum wells (MQWs) are epitaxially grown with varying well thicknesses and barriers. The retaining high material quality of those complex structures is probed by advanced characterization methods, such as atom probe tomography and dark-field electron holography to extract composition parameters and strain, used further for band structure calculations. Special emphasis is put on the impact of carrier confinement and quantization effects, evaluated by photoluminescence and validated by theoretical calculations. As shown, particularly MQW heterostructures promise the highest potential for efficient next generation complementary metal-oxide-semiconductor (CMOS)-compatible group IV lasers.

11.
Phys Rev Lett ; 120(16): 165501, 2018 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-29756931

RESUMO

The binary Kob-Andersen (KA) Lennard-Jones mixture is the standard model for computational studies of viscous liquids and the glass transition. For very long simulations, the viscous KA system crystallizes, however, by phase separating into a pure A particle phase forming a fcc crystal. We present the thermodynamic phase diagram for KA-type mixtures consisting of up to 50% small (B) particles showing, in particular, that the melting temperature of the standard KA system at liquid density 1.2 is 1.028(3) in A particle Lennard-Jones units. At large B particle concentrations, the system crystallizes into the CsCl crystal structure. The eutectic corresponding to the fcc and CsCl structures is cutoff in a narrow interval of B particle concentrations around 26% at which the bipyramidal orthorhombic PuBr_{3} structure is the thermodynamically stable phase. The melting temperature's variation with B particle concentration at two constant pressures, as well as at the constant density 1.2, is estimated from simulations at pressure 10.19 using isomorph theory. Our data demonstrate approximate identity between the melting temperature and the onset temperature below which viscous dynamics appears. Finally, the nature of the solid-liquid interface is briefly discussed.

12.
J Trace Elem Med Biol ; 49: 192-201, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29551464

RESUMO

Recently, the pro-inflammatory effects of metal inert gas brazing welding fumes containing zinc and copper have been demonstrated in humans. Here, murine, rat and human precision cut lung slices (PCLS) were incubated in welding fume containing media with 0.1, 1, 10 and 100 µg/ml for 24 or 48 h. 24 h incubation were determined either by incubation for the total time or for only 6 h followed by a 18 h post-incubation phase. Cytotoxicity, proliferation and DNA repair rates, and cytokine levels were determined. Welding fume particle concentrations of 0.1 and 1 µg/ml showed no toxic effects on PCLS of all three species, while for 10 and 100 µg/ml a concentration-dependent toxicity occurred. Proliferation and DNA repair rates were reduced for all tested concentrations and incubation times. Additionally, the cytokine levels in the supernatants were markedly reduced, while after 6 h of exposure with 18 h of post-incubation time a trend towards increased cytokine levels occurred. PCLS are a reliable and feasible method to assess and offer a prediction of toxic effects of welding fume particles on human lungs. Rat PCLS showed similar responses compared to human PCLS and are suitable for further evaluation of toxic effects exerted by welding fume particles.


Assuntos
Poluentes Ocupacionais do Ar/toxicidade , Cobre/química , Pulmão/efeitos dos fármacos , Ratos Wistar , Zinco/química , Animais , Ensaio de Imunoadsorção Enzimática , Humanos , Técnicas In Vitro , Exposição por Inalação/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Soldagem
13.
Sci Rep ; 8(1): 5123, 2018 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-29572534

RESUMO

Recently, side effects of plasma expanders like hydroxyethyl starch and gelatine gained considerable attention. Most studies have focused on the kidneys; lungs remain unconsidered. Isolated mouse lungs were perfused for 4 hours with buffer solutions based on hydroxyethyl starch (HES) 130/0.4, HES 200/0.5 or gelatine and ventilated with low or high pressure under physiological pH and alkalosis. Outcome parameters were cytokine levels and the wet-to-dry ratio. For cytokine release, murine and human PCLS were incubated in three different buffers and time points.In lungs perfused with the gelatine based buffer IL-6, MIP-2 and KC increased when ventilated with high pressure. Wet-to-dry ratios increased stronger in lungs perfused with gelatine - compared to HES 130/0.4. Alkalotic perfusion resulted in higher cytokine levels but normal wet-to-dry ratio. Murine PCLS supernatants showed increased IL-6 and KC when incubated in gelatine based buffer, whereas in human PCLS IL-8 was elevated. In murine IPL HES 130/0.4 has lung protective effects in comparison to gelatine based infusion solutions, especially in the presence of high-pressure ventilation. Gelatine perfusion resulted in increased cytokine production. Our findings suggest that gelatine based solutions may have side effects in patients with lung injury or lung oedema.


Assuntos
Citocinas/biossíntese , Gelatina , Derivados de Hidroxietil Amido , Pulmão/metabolismo , Animais , Feminino , Gelatina/efeitos adversos , Gelatina/farmacologia , Humanos , Derivados de Hidroxietil Amido/efeitos adversos , Derivados de Hidroxietil Amido/farmacologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos BALB C
14.
J Chem Phys ; 148(8): 081101, 2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-29495764

RESUMO

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.

15.
J Clin Psychol ; 74(1): 5-42, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28505384

RESUMO

OBJECTIVE: Previous reviews have found equivocal evidence of an association between therapists' internalized relational models and the therapeutic relationship and have neglected empirical literature based on Sullivan's notion of introject. This review expanded upon previous reviews to examine the effect of therapist internalized relational models on a broader conceptualization of the therapeutic relationship. METHOD: Systematic search processes identified 22 papers measuring therapist attachment and/or introject and therapeutic relationship: 19 on therapist attachment, 5 on introject with 2 overlapping. RESULTS: Overall, despite heterogeneity in design and variable methodological quality, evidence suggests that therapist attachment affects therapeutic relationship quality, observed in client-rated evaluation, therapist negative countertransference, empathy, and problems in therapy. Interaction effects between client and therapist attachment style were also found. Evidence suggesting that therapist introject also affects therapeutic relationship quality, including therapists' manner and feelings toward their clients, was stronger. CONCLUSION: Evidence clearly shows that therapists' internalized relational models affect the therapeutic relationship. More research is necessary to clarify exactly how therapist and client internalized relational models interact and translate these findings into clinical practice.


Assuntos
Empatia , Pessoal de Saúde/psicologia , Apego ao Objeto , Relações Profissional-Paciente , Psicoterapia , Humanos
16.
Sci Rep ; 7: 45187, 2017 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-28345662

RESUMO

A tonically high level of brain arousal and its hyperstable regulation is supposed to be a pathogenic factor in major depression. Preclinical studies indicate that most antidepressants may counteract this dysregulation. Therefore, it was hypothesized that responders to antidepressants show a) a high level of EEG-vigilance (an indicator of brain arousal) and b) a more stable EEG-vigilance regulation than non-responders. In 65 unmedicated depressed patients 15-min resting-state EEGs were recorded off medication (baseline). In 57 patients an additional EEG was recorded 14 ± 1 days following onset of antidepressant treatment (T1). Response was defined as a ≥50% HAMD-17-improvement after 28 ± 1 days of treatment (T2), resulting in 29 responders and 36 non-responders. Brain arousal was assessed using the Vigilance Algorithm Leipzig (VIGALL 2.1). At baseline responders and non-responders differed in distribution of overall EEG-vigilance stages (F2,133 = 4.780, p = 0.009), with responders showing significantly more high vigilance stage A and less low vigilance stage B. The 15-minutes Time-course of EEG-vigilance did not differ significantly between groups. Exploratory analyses revealed that responders showed a stronger decline in EEG-vigilance levels from baseline to T1 than non-responders (F2,130 = 4.978, p = 0.005). Higher brain arousal level in responders to antidepressants supports the concept that dysregulation of brain arousal is a possible predictor of treatment response in affective disorders.


Assuntos
Antidepressivos/uso terapêutico , Nível de Alerta/fisiologia , Encéfalo/fisiopatologia , Transtorno Depressivo Maior/tratamento farmacológico , Eletroencefalografia/métodos , Adulto , Algoritmos , Transtorno Depressivo Maior/fisiopatologia , Transtorno Depressivo Maior/psicologia , Humanos , Masculino , Pessoa de Meia-Idade , Escalas de Graduação Psiquiátrica , Resultado do Tratamento
17.
Clin Psychol Psychother ; 24(1): 171-185, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26689443

RESUMO

BACKGROUND: Therapists' personal practice of therapy techniques can impact on a range of areas, including: empathy for the client, therapeutic understanding, therapist skills and self-awareness. Compassion Focused Therapy (CFT) draws extensively on personal practice during training, and on-going personal practice is encouraged. However, the impact of this has not been examined. OBJECTIVES: To explore therapists' experiences of personal practice in relation to CFT, and the impact this has upon them and their therapeutic work. DESIGN: A qualitative approach was adopted, using inductive thematic analysis. METHODS: Ten therapists, who had trained in CFT, took part in a semi-structured interview to explore their experiences of personal practice. RESULTS: Five main themes were identified. These highlighted that: (1) experiences of personal practice often felt strange to start with but were surprisingly powerful; (2) with practice, the exercises became more automatic and could be adopted as a 'way of life'; (3) personal practice was felt to increase both self-compassion and compassion for others; (4) personal practice often helped participants to feel more present for their clients; and (5) participants were more aware of what they were bringing to therapy. CONCLUSIONS: This exploratory study demonstrated that personal practice is an important part of CFT training and can have a positive impact upon therapists both personally and professionally. It is concluded that the results justify further research in order to establish the applicability of these findings with a larger sample. Copyright © 2015 John Wiley & Sons, Ltd. KEY PRACTITIONER MESSAGES: Personal practice facilitates experiential learning and is an important element of CFT training, which impacts on both personal and professional development. CFT trainers need to ensure that sufficient time is provided for both personal practice and reflection. CFT trainees should be aware that initial reactions to personal practice can be powerful and sometimes unsettling. As for therapy itself, working through fears, blocks and resistances is important. Personal practice is a valuable self-care strategy, and therapists are encouraged to engage in personal practice after training.


Assuntos
Empatia , Teoria da Construção Pessoal , Relações Profissional-Paciente , Psicoterapia/métodos , Adulto , Idoso , Conscientização , Feminino , Humanos , Entrevista Psicológica , Masculino , Pessoa de Meia-Idade , Aprendizagem Baseada em Problemas , Pesquisa Qualitativa , Autoimagem
18.
J Phys Chem B ; 120(32): 7970-4, 2016 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-27494438

RESUMO

Many liquids have curves (isomorphs) in their phase diagrams along which structure, dynamics, and some thermodynamic quantities are invariant in reduced units. A substantial part of their phase diagrams is thus effectively one dimensional. The shapes of these isomorphs are described by a material-dependent function of density, h(ρ), which for real liquids is well approximated by a power law, ρ(γ). However, in simulations, a power law is not adequate when density changes are large; typical models, such as Lennard-Jones liquids, show that γ(ρ) ≡ d ln h(ρ)/d ln ρ is a decreasing function of density. This article presents results from computer simulations using a new pair potential that diverges at a nonzero distance and can be tuned to give a more realistic shape of γ(ρ). Our results indicate that the finite size of molecules is an important factor to take into account when modeling liquids over a large density range.

19.
Nat Commun ; 7: 12386, 2016 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-27530064

RESUMO

Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature-pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system.

20.
J Chem Phys ; 144(23): 231101, 2016 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-27334147

RESUMO

The recent theoretical prediction by Maimbourg and Kurchan [e-print arXiv:1603.05023 (2016)] that for regular pair-potential systems the virial potential-energy correlation coefficient increases towards unity as the dimension d goes to infinity is investigated for the standard 12-6 Lennard-Jones fluid. This is done by computer simulations for d = 2, 3, 4 going from the critical point along the critical isotherm/isochore to higher density/temperature. In both cases the virial potential-energy correlation coefficient increases significantly. For a given density and temperature relative to the critical point, with increasing number of dimension the Lennard-Jones system conforms better to the hidden-scale-invariance property characterized by high virial potential-energy correlations (a property that leads to the existence of isomorphs in the thermodynamic phase diagram, implying that it becomes effectively one-dimensional in regard to structure and dynamics). The present paper also gives the first numerical demonstration of isomorph invariance of structure and dynamics in four dimensions. Our findings emphasize the need for a universally applicable 1/d expansion in liquid-state theory; we conjecture that the systems known to obey hidden scale invariance in three dimensions are those for which the yet-to-be-developed 1/d expansion converges rapidly.

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