The noncovalent interaction energy as a function of the core extension in double-walled carbon nanotubes (DWCNT) was accurately calculated in the frame of density functional theory, considering ...dispersion correction and without resorting to adjustable parameters. A linear correlation between the change of the noncovalent energy and core displacement was established for the first time through a pure quantum mechanics approach; hence, the force needed to pull out the DWCNT core was accurately calculated. This force was found to be in good agreement with experimental values reported in the literature. Furthermore, the effect of the DWCNT edges was considered in the calculation of the potential energy profile, and the frequency, associated with the oscillation of core inlet, was calculated for the first time through a quantum approach. This frequency falls in the low infrared region, and it depends on the chemical nature of the oscillator edges. The work highlights that the noncovalent H···π interaction controls the inner shell oscillation and it should be considered, beyond the stacking between inner and outer walls, as a driving force for the activation of the telescopic process. As a result, this noncovalent interaction can be tuned for the design of nano-dynamometers with well-defined force constants.
Many membrane-based ion separation technologies require monovalent cations selectivity. However, available membranes usually show limited specific ion selectivity. In order to provide basic ...information on the membrane ion selectivity, the confinement effect on narrow pores disrupting the ion hydration is investigated in this work, with the aim to provide a new alternative to classical Cation Exchange Membranes (CEM). Starting from solvated cations structures used as templates and obtained by a quantum approach, Single-Wall Carbon Nanotubes (SWCNT) with ad-hoc designed diameters were chosen to perform in-silico experiments of single-cation permeation through CNT by means of Molecular Dynamics simulations, for which partial charges at nanotube inlets were parametrized through ab initio calculations. Cations' trajectories and energy decomposition analysis suggest that 100 % perm-selectivity towards Na+ with respect to Ca2+ and Mg2+ is virtually attainable with CNT of 1.33 nm diameter. Interestingly, the origin of this behaviour lays on thermodynamics rather than on size exclusion mechanisms. Opposite to polymeric homogeneous CEM, showing higher affinity for multivalent cations, an inverted trend was found for CNT in terms of hydration free energies, where Na+ shows more affinity up to 36 kJ/mol. Finally, total rejection of Cl− was observed in the range of CNT diameters investigated.
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•Hydrated cations DFT-COSMO optimized structures as templates for CNT diameters.•Selectivity of monovalent versus divalent cations: a proof of concept•Single cation 200 ns MD trajectories through 4 nm-long CNT models in water•Na+ 36 kJ/mol affinity vs. Mg2+ and Ca2+ total rejection with CNT 1.33 nm diameter•Total rejection of Cl− anions through zig-zag CNTs 1.33–1.96 nm diameter
Although the physiologic role of muscarinic receptors in bladder function and the therapeutic efficacy of muscarinic antagonists for the treatment of overactive bladder are well established, the role ...of β
-adrenergic receptors (β
ARs) and their potential as therapeutics is just emerging. In this manuscript, we characterized the pharmacology of a novel β
AR agonist vibegron (MK-4618, KRP-114V) and explored mechanistic interactions of β
AR agonism and muscarinic antagonism in urinary bladder function. Vibegron is a potent, selective full β
AR agonist across species, and it dose dependently increased bladder capacity, decreased micturition pressure, and increased bladder compliance in rhesus monkeys. The relaxation effect of vibegron was enhanced when combined with muscarinic antagonists, but differentially influenced by muscarinic receptor subtype selectivity. The effect was greater when vibegron was co-administered with tolterodine, a nonselective antagonist, compared with coadministration with darifenacin, a selective M3 antagonist. Furthermore, a synergistic effect for bladder strip relaxation was observed with the combination of a β
AR agonist and tolterodine in contrast to simple additivity with darifenacin. To determine expression in rhesus bladder, we employed a novel β
AR agonist probe,
HMRL-037, that selectively labels β
receptors in both urothelium and detrusor smooth muscle. Vibegron administration caused a dose-dependent increase in circulating glycerol and fatty acid levels in rhesus and rat in vivo, suggesting these circulating lipids can be surrogate biomarkers. The translation of our observation to the clinic has yet to be determined, but the combination of β
AR agonists with M2/M3 antimuscarinics has the potential to redefine the standard of care for the pharmacological treatment of overactive bladder.
The CABRI experimental pulse reactor is devoted to the study of reactivity-initiated accidents (RIAs), for the purpose of the CABRI International Program (CIP), managed by the French Safety and ...Radiation Protection Institute (IRSN). CABRI's hodoscope equipment detects the fast neutrons emitted during a power pulse by a tested rod, positioned inside a dedicated test loop reproducing either sodium reactor or pressurized water reactor (PWR) conditions. One of the most important parameters measured by the hodoscope detectors is the signal-to-noise ratio (SNR), characterizing the fraction of neutrons directly coming from the test rod ("signal") over neutrons coming from the core ("noise"). In this article, the method used to calculate the SNR using a 2-D model of CABRI, with the MCNP6.2 Monte Carlo code, will be detailed. Comparisons between the calculated and measured SNRs for different configurations are in quite good agreement. Another parameter of interest is the so-called "scattering coefficient," which corresponds to the fraction of neutrons coming from the test rod and being scattered between their birth and their detection. This parameter is used to enhance the analysis of the fuel displacement that may happen during the power transient. To estimate this coefficient, an innovative method using a combination of different options available in MCNP6.2 has been used. Computed coefficients show a slight discrepancy with the measurements. Finally, the sensitivity of the SNR and scattering coefficient to technological parameters and nuclear data libraries is discussed.
This article aims at inventorying the knowledge on nuclear heating measurements in a mixed (n,γ) field in low-power research reactors using ThermoLuminescent Detectors (TLDs), Optically Stimulated ...Luminescent Detectors (OSLDs) and Ionization Chambers. The difficulty in measuring a mixed (n,γ) field in a reactor configuration lies in quantifying the contribution of the gamma photons and neutrons to the full signal measured by these detectors. The algorithms and experimental protocols developed together with the calculation methods used to assess the contribution of the neutron dose to the total integrated dose as measured by these detectors will be described in this article. This ‘inventory’ will be used to summarize the best methods to be used in relation to the requirements.
The CABRI experimental pulse reactor, located at the Cadarache nuclear research center, southern France, is devoted to the study of Reactivity Initiated Accidents (RIA) for the purpose of the CABRI ...International Program (CIP), managed by IRSN in the framework of an OECD/NEA agreement. The hodoscope equipment installed in the CABRI reactor is an almost unique online fuel motion monitoring system, thanks to the measurement of the fast neutrons emitted during a power pulse by a tested rod positioned inside a dedicated test loop reproducing PWR conditions. This system is dedicated to the analysis of fuel displacement. Hence, one of the most important parameter measured by the hodoscope detectors is the Signal over Noise Ratio (SNR), characterizing the fraction of neutrons directly coming from the test rod (“signal”) over neutrons coming from the core (“noise”).
It is interesting to calculate the SNR in order to define some quantitative criterions to improve hodoscope measurements and to understand if any modification linked to the test loop may significantly change this essential parameter.
Another parameter of interest is the so-called “scattering coefficient”, which corresponds to the fraction of neutrons coming from the test rod and being scattered between their birth and their detection. This parameter is used to enhance the analysis of the fuel displacement which may happen during the power transient.
In this article, the method used to calculate the SNR using MCNP6.2 Monte Carlo code will be detailed. Because the hodoscope detectors are located far away from the test rod (up to 4 meters), a 2D model of CABRI core and instrumentation has been implemented. No variance reduction techniques have been used to solve this problem in order to record the place of birth of neutron which contributes to the different scores with the goal to perform a detailed analysis of the SNR. This strategy allows to access numerically to the “scattering coefficient”.
Finally, the comparison between calculated and measured SNR for a case study will be carried out. A quite good agreement between the 2D simulations and experiments recently performed in the CABRI reactor has been obtained.
The objective of this study is to develop nuclear heating measurement methods in Zero Power experimental reactors. This paper presents the analysis of Thermo-Luminescent Detector (TLD) and Optically ...Stimulated Luminescent Detectors (OSLD) experiments in the \hbox{UO}_{2} core of the MINERVE research reactor at the CEA Cadarache.
Organizations value insights from reflexive, iterative processes of designing interactive environments that reflect user experience. "I really like this definition of experience architecture, which ...requires that we understand ecosystems of activity, rather than simply considering single-task scenarios."—Donald Norman (The Design of Everyday Things)
Background Pelvic floor dysfunction (PFD) occurs when muscles of the pelvic floor become weakened, impaired, or experience tension leading to a variety of complications. Due to the reactive nature ...and high demands of many sports, athletes are at increased susceptibility and of particular interest concerning PFD. Hypothesis/Purpose The purpose of this study was to explore the prevalence of PFD among college-aged athletes, assess how PFD impacted athletic performance, and identify contributing factors for increased likelihood of PFD in athletes. Study Design Cross-Sectional Study Methods All fully active LVC NCAA Division 3 athletes were recruited for screening for PFD using the Cozean Pelvic Dysfunction Screening Protocol and were surveyed on their self-knowledge of PFD. Athletes who scored ≥ 3 on this tool completed an additional survey, created by the investigators, to identify the impact PFD had on their athletic performance and personal life and were then randomly assigned to one of three investigators to undergo a noninvasive coccygeal assessment to determine underactive, overactive, or normal pelvic floor muscle (PFM) activity. Results Fifty-three Division III male and female athletes between the ages of 18-25 years old participated in the study. Statistically significant differences were found between Cozean scores and demographic factors of age ( p <0.001), gender ( p <0.05), self-knowledge of PFD ( p <0.001), and sport ( p <0.001) among all participants that contributed to the increased likelihood of PFD. Thirteen athletes scored ≥ 3 on the Cozean with the 92.3% experiencing under/over active PFM activity and the majority indicating that PFD significantly impacted their athletic performance and quality of life. Conclusion The results indicate that older female NCAA Division III college athletes who participate in swimming and who possess self-knowledge of PFD are more likely to experience PFD. Additionally, these athletes are likely to encounter a significant impact on their athletic performance and quality of life. These results provide preliminary evidence on the need of PFD awareness and assessment among college athletes. Level of Evidence Level 3b
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