Force matching and iterative Boltzmann inversion coarse grained force fields for ZIF-8.

Despite the intense activity at electronic and atomistic resolutions, coarse grained (CG) modeling of metal-organic frameworks remains largely unexplored. One of the main reasons for this is the lack of adequate CG force fields. In this work, we present iterative Boltzmann inversion and force matching (FM) force fields for modeling ZIF-8 at three different coarse grained resolutions. Their ability to reproduce structure, elastic tensor, and thermal expansion is evaluated and compared with that of MARTINI force fields considered in previous work [Alvares et al., J. Chem. Phys. 158, 194107 (2023)]. Moreover, MARTINI and FM are evaluated for their ability to depict the swing effect, a subtle phase transition ZIF-8 undergoes when loaded with guest molecules. Overall, we found that all our force fields reproduce structure reasonably well. Elastic constants and volume expansion results are analyzed, and the technical and conceptual challenges of reproducing them are explained. Force matching exhibits promising results for capturing the swing effect. This is the first time these CG methods, widely applied in polymer and biomolecule communities, are deployed to model porous solids. We highlight the challenges of fitting CG force fields for these materials.

Coarse-grained modeling of zeolitic imidazolate framework-8 using MARTINI force fields.

In this contribution, the well-known MARTINI particle-based coarse graining approach is tested for its ability to model the ZIF-8 metal-organic framework. Its capability to describe structure, lattice parameters, thermal expansion, elastic constants and amorphization is evaluated. Additionally, the less coarsened models were evaluated for reproducing the swing effect and the host-guest interaction energies were analyzed. We find that MARTINI force fields successfully capture the structure of the Metal-Organic Framework (MOF) for different degrees of coarsening, with the exception of the MARTINI 2.0 models for the less coarse mapping. MARTINI 2.0 models predict more accurate values of C11 and C12, while MARTINI 3.0 has a tendency to underestimate them. Among the possibilities tested, the choice of bead flavors within a particular MARTINI version appears to have a less critical impact in the simulated properties of the empty framework. None of the coarse-grained (CG) models investigated were able to capture the amorphization nor the swing effect within the scope of MD simulations. A perspective on the importance of having a proper Lennard-Jones (LJ) parametrization for modeling guest-MOF and MOF-MOF interactions is highlighted.

Blue LED as a new treatment to vaginal stenosis due pelvic radiotherapy: Two case reports.

BACKGROUND: Currently, the advancement cancer treatment technology improves overall survival, however, adverse events are still a challenge for health professional. Genitourinary syndrome of menopause and vaginal stenosis are conditions that impact the quality of life of patients undergoing radiotherapy. We present two such cases in patients with previous cervical and endometrial cancer. These conditions were handled with an innovative method using an energy-based device with blue light emitting diode for concomitant vaginal and vulvar irradiation. Positive impact in clinical findings, cytologic changes, and referred symptoms were documented. CASE SUMMARY: One patient diagnosed with vaginal severe vaginal stenosis with previous cervix cancer treatment and other patient diagnosed with mild stenosis with severe dyspareunia and recent endometrium cancer treatment were considered for vulvovaginal treatment with weekly blue led device and closely evaluated with repeated validated questionnaires and cytological samples. CONCLUSION: This innovative technique showed an improvement in all areas of the examiner's criteria, the cytological criteria, and most bothered symptoms.

Ab initiobased interionic interactions in calcium aluminotitanate oxide melts: structure and diffusion.

Calcium aluminotitanate (CaO-Al2O3-TiO2) ternary oxides are of fundamental interest in Materials as well as Earth and environmental science, and a key system for several industrial applications. As their properties at the atomic scale are scarcely known, interionic interactions for the melts are built from a bottom up strategy consisting in fitting first only Al2O3, CaO and TiO2single oxide compounds separately with a unified description of the oxygen charge and O-O interaction term. For this purpose, a mean-square difference minimization of the partial pair-correlation functions with respect to theab initioreference was performed. The potentials for the ternary oxide are finally built straightforwardly by adding purely Coulomb terms for dissimilar cation-cation interactions without further fit. This general and unified approach is transferable and successfully describes the structural and diffusion properties of the three single oxides as well as the ternary melts simultaneously. A possible underlying structural mechanism at the origin of the diffusion evolution with TiO2content is proposed based on the formation of Ti induced triply bonded oxygen.

Thermodynamics and structural properties of CaO: A molecular dynamics simulation study.

A detailed theoretical study of CaO in the solid and liquid states by means of combined classical and ab initio molecular dynamics simulations is presented. Evolution of the specific heat capacity at constant pressure as a function of temperature is studied, and the melting temperature and enthalpy of fusion are determined. It is shown that an empirical Born-Mayer-Huggins potential gives a good representation of pure CaO in the liquid and solid states as compared to available experimental data and density functional theory calculations. Consistency of the predicted results obtained for CaO with the data available in commercial thermodynamic databases and experimental values in the literature is discussed. The present methodology and theoretical results provide a new accurate basis for calculations of thermodynamic properties in a temperature range that is hardly accessible by experiments.

The relation of the pelvis and the perineal function in incontinent women: A neglected subject.

AIMS: To Compare the angular parameters of the pelvis of continents and incontinent women and to correlate them with the electrical activity and the function of the pelvic floor muscles. METHODS: Cross-sectional study. Incontinent and continent women, aged between 18 and 59 years. The anatomical points were marked following the SAPO protocols, the photographic records were made and analyzed through the SAPO Software. The evaluation of the function of the MPF was performed by bidigital vaginal palpation, using the PERFECT scheme. Surface electromyographic analysis was performed in dorsal decubitus and orthostasis. RESULTS: The sample consisted of 40 women, 20 with SUI (IG) and 20 continents (CG), matched by age. The mean age in the CG was 43.5 years (SD 8.4), while in the IG it was 47.1 years (SD 7.8) (P = 0.16). The pelvic angle in the CG presented a mean of -14.3 ± 4.6 and the IG -16.6 ± 4.4 (P = 0.02). When compared to normality, IG presented an accentuation of anterior slope in both analyzed views (P = 0.01). There was a moderate correlation in the IG between the electrical activity of the basal pelvis in orthostasis and the anterior pelvic tilt angles in the right lateral views r = 0.51 (P = 0.02) and left lateral r = 0.46 (P = 0.04). No correlation was found in the CG. CONCLUSIONS: In the present sample, incontinent women have a greater anterior slope of the pelvis, and the greater the degree of anterior slope, the greater the electrical activity of the PFM, during rest, and in orthostasis.