828 research outputs found
Second-Harmonic Scattering as a Probe of Structural Correlations in Liquids
Second-harmonic scattering experiments of water and other bulk molecular
liquids have long been assumed to be insensitive to interactions between the
molecules. The measured intensity is generally thought to arise from incoherent
scattering due to individual molecules. We introduce a method to compute the
second-harmonic scattering pattern of molecular liquids directly from atomistic
computer simulations, which takes into account the coherent terms. We apply
this approach to large-scale molecular dynamics simulations of liquid water,
where we show that nanosecond second-harmonic scattering experiments contain a
coherent contribution arising from radial and angular correlations on a length
scale of < 1 nm, much shorter than had been recently hypothesized (Shelton, D.
P. J. Chem. Phys. 2014, 141). By combining structural correlations from
simulations with experimental data (Shelton, D. P. J. Chem. Phys. 2014, 141),
we can also extract an effective molecular hyperpolarizability in the liquid
phase. This work demonstrates that second-harmonic scattering experiments and
atomistic simulations can be used in synergy to investigate the structure of
complex liquids, solutions, and biomembranes, including the intrinsic
intermolecular correlations
The Moderating Effect of Positive Sexual Self-Concept on the Relationship Between Disability Impact and Satisfaction with Life.
Research has been produced assessing both the concept of Life Satisfaction and the impact of disability. However, there has been a lack of research assessing the intersection of disability, sexuality, and life satisfaction. This study sought to understand the relationship between improved sexual self-concept, life satisfaction, and disability impact. Sexual self-concept was examined as a moderator of the relationship between disability impact and life satisfaction. It was hypothesized that improved sexual self-concept among those living with a disability will have a positive and correlating effect on life satisfaction. Additionally, it was hypothesized that the relationship between disability impact and satisfaction with life would be stronger among those who had higher sexual self-concept ratings. The study consisted of 104 adults with cerebral palsy, spina bifida, and other neurodevelopmental disabilities. Individuals completed the World Health Organization Disability Assessment Schedule (WHODAS), four subscales of the Multidimensional Sexual Self Concept Questionnaire (MSSCQ), and the Satisfaction with Life Scale (SWLS) to assess disability impact, sexual self-concept, and satisfaction with life respectively. Results indicated that higher levels of sexual self-concept were associated with higher life satisfaction rates. Furthermore, the relationship between disability impact and satisfaction with life was stronger among those who had higher sexual self-concept scores. Lastly, via moderation analysis, results indicated the relationship between disability impact and life satisfaction was moderated by sexual self-concept. Thus, there appears a need to cultivate positive sexual self-concept in individuals living with disabilities in an effort to contribute to life satisfaction
Beam diagnostics for charge and position measurements in ELI-NP GBS
The advanced source of Gamma-ray photons to be built in Bucharest (Romania), as part of the ELI-NP European Research Infrastructure, will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam and a high intensity recirculated laser pulse. An S-Band photoinjector and the following C-band Linac at a maximum energy of 720MeV, under construction by an European consortium (EurogammaS) led by INFN, will operate at 100Hz repetition rate with trains of 32 electron bunches, separated by 16ns and a 250pC nominal charge. The different BPMs and current transformers used to measure transverse beam position and charge along the LINAC are described. Design criteria, production status and bench test results of the charge and position pickups are reported in the paper, together with the related data acquisition systems
Molecular Dynamics Simulation of Solvent-Polymer Interdiffusion. I. Fickian diffusion
The interdiffusion of a solvent into a polymer melt has been studied using
large scale molecular dynamics and Monte Carlo simulation techniques. The
solvent concentration profile and weight gain by the polymer have been measured
as a function of time. The weight gain is found to scale as t^{1/2}, which is
expected for Fickian type of diffusion. The concentration profiles are fit very
well assuming Fick's second law with a constant diffusivity. The diffusivity
found from fitting Fick's second law is found to be independent of time and
equal to the self diffusion constant in the dilute solvent limit. We separately
calculated the diffusivity as a function of concentration using the Darken
equation and found that the diffusivity is essentially constant for the
concentration range relevant for interdiffusion.Comment: 17 pages and 7 figure
Pulsed Current Effect on the Hard Anodizing of an AlSi10Mg Aluminum Alloy Obtained via Additive Manufacturing
The hard anodizing treatments of cast Al-Si alloys are notoriously difficult. Indeed, their microstructural features hinder the growth of a uniform, compact, and defect-free anodic oxide. In this paper, AlSi10Mg samples, produced via Gravity Casting (GC) and Additive Manufacturing, i.e., Laser Powder Bed Fusion (L-PBF), were hard anodized in a sulfuric acid bath, in order to verify how the particular microstructure obtained via L-PBF affects the thickness, hardness, compactness, and defectiveness of the anodic oxide. Moreover, for the first time, Pulsed Direct Current (PDC) procedures were used to perform the hard anodizing treatments on additively manufactured AlSi10Mg alloy. Several combinations of temperature and electrical parameters, i.e., current density, frequency, and Duty Cycle, were tested. The anodized samples were characterized through optical microscopy analysis, Scanning Electron Microscopy (SEM) analysis, and accelerated corrosion tests, i.e., Potentiodynamic Polarization (POL) and Electrochemical Impedance Spectroscopy (EIS) measurements. The PDC procedures allowed improvement of the compromise between evenness, compactness, and defectiveness. Among the attempted PDC procedures, a specific combination of electrical parameters and temperature allowed the best results to be obtained, i.e., the highest hardness and the lowest volumetric expansion values without compromising the oxide quality rating and the corrosion resistance behavior. However, none of the attempted PCD strategies allowed the hardness values obtained on samples produced via GC to be reached
The European Union, borders and conflict transformation: the case of Cyprus
Much of the existing literature on the European Union (EU), conflict transformation and border dynamics has been premised on the assumption that the nature of the border determines EU intervention and the consequences that flow from this in terms of EU impact. The article aims to transcend this literature through assessing how domestic interpretations influence EU border transformation in conflict situations, taking Cyprus as a case study. Moreover, the objective is to fuse the literature on EU bordering impact and perceptions of the EU’s normative projection in conflict resolution. Pursuing this line of inquiry is an attempt to depart from the notion of borders being constructed solely by unidirectional EU logics of engagement or bordering practices to a conceptualization of the border as co-constituted space, where the interpretations of the EU’s normative projections by conflict parties, and the strategies that they pursue, can determine the relative openness of the EU border
Real-life appraisal on blood pressure targets achievement in adult outpatients at high cardiovascular risk
Background and aim: Although hypertension guidelines highlight the benefits of achieving the recommended blood pressure (BP) targets, hypertension control rate is still insufficient, mostly in high or very high cardiovascular (CV) risk patients. Thus, we aimed to estimate BP control in a cohort of patients at high CV risk in both primary and secondary prevention. Methods and results: A single-center, cross-sectional study was conducted by extracting data from a medical database of adult outpatients aged 40–75 years, who were referred to our Hypertension Unit, Rome (IT), for hypertension assessment. Office BP treatment targets were defined according to 2018 ESC/ESH guidelines as: a)<130/80 mmHg in individuals aged 40–65 years; b)<140/80 mmHg in subjects aged >65 years. Primary prevention patients with SCORE <5% were considered to be at low-intermediate risk, whilst individuals with SCORE ≥5% or patients with comorbidities were defined to be at very high risk. Among 6354 patients (47.2% female, age 58.4 ± 9.6 years), 4164 (65.5%) were in primary prevention with low-intermediate CV risk, 1831 (28.8%) in primary prevention with high-very high CV risk and 359 (5.6%) in secondary prevention. In treated hypertensive outpatients, uncontrolled hypertension rate was significantly higher in high risk primary prevention than in low risk primary prevention and secondary prevention patients (18.4% vs 24.4% vs. 12.5%, respectively; P < 0.001). In high risk primary prevention diabetic patients only 10% achieved the recommended BP targets. Conclusions: Our data confirmed unsatisfactory BP control among high-risk patients, both in primary and secondary prevention, and suggest the need for a more stringent BP control policies in these patients
Structure of a model TiO2 photocatalytic interface
The interaction of water with TiO2 is crucial to many of its practical
applications, including photocatalytic water splitting. Following the first
demonstration of this phenomenon 40 years ago there have been numerous studies
of the rutile single-crystal TiO2(110) interface with water. This has provided
an atomic-level understanding of the water-TiO2 interaction. However, nearly
all of the previous studies of water/TiO2 interfaces involve water in the
vapour phase. Here, we explore the interfacial structure between liquid water
and a rutile TiO2(110) surface pre-characterized at the atomic level. Scanning
tunnelling microscopy and surface X-ray diffraction are used to determine the
structure, which is comprised of an ordered array of hydroxyl molecules with
molecular water in the second layer. Static and dynamic density functional
theory calculations suggest that a possible mechanism for formation of the
hydroxyl overlayer involves the mixed adsorption of O2 and H2O on a partially
defected surface. The quantitative structural properties derived here provide a
basis with which to explore the atomistic properties and hence mechanisms
involved in TiO2 photocatalysis
Comparison of pure and mixed gas permeation of the highly fluorinated polymer of intrinsic microporosity PIM-2 under dry and humid conditions: Experiment and modelling
This manuscript describes the gas separation performance of PIM-2, a partially fluorinated linear copolymer synthesized from 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane (TTSBI) and decafluorobiphenyl (DFBP). As one of the early members of the family of polymers of intrinsic microporosity, it had never been tested as a gas separation membrane because of insufficient mechanical resistance. This has been solved only recently, allowing the preparation of robust self-standing films. Molecular modelling studies demonstrated a high fractional free volume (34%) and an elevated surface area (642 m2 g-1), and the latter is in good agreement with experimental BET results. Pure gas permeabilities measured on a fixed-volume time-lag instrument at 1 bar compare well with the results of mixed separation tests on a variable volume setup from 1-6 bar(a). Molecular modelling and independent sorption measurements on a gravimetric sorption balance both show strong dual-mode sorption behaviour, especially for CO2 and to a lesser extent for CH4. Temperature-dependent pure gas permeation measurements show typical Arrhenius behaviour, with a clear increase in the activation energy for diffusion with the increasing molecular size of the gas, indicating high size-selectivity. This is in agreement with the highly rigid PIM structure, determined by AFM force spectroscopy measurements. The dual-mode behaviour results in a moderate pressure dependence of the CO2 permeability and the CO2/N2 and CO2/CH4 selectivity, all slightly decreasing with increasing pressure. The presence of humidity in the gas stream has a remarkable small effect on the membrane performance, which is probably due to the high fluorine content and the consequently low water vapour solubility in the polymer, as confirmed by gravimetric sorption measurements. The manuscript describes an extensive study on the structure-property relationships in PIM-2. © 2019 Elsevier B.V.European Commission, EC Grantová Agentura Ceské Republiky, GA Ä?R: 18-05484S --Research on biogas upgrading presented in this work was supported by EU structural funding in the frame of Operational Programme Research, Development and Education, project No. CZ.02.1.01./0.0/0.0/17_049/0008419 “COOPERATION”. This work was further supported by the CNR-CAS bilateral agreement 2016–2018 “Innovative polymeric membranes for pervaporation and advanced gas and vapour separations” and by the Czech Science Foundation (grant no. 18-05484S ). Appendix A -
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