ArnHF van der Waals clusters revisited: II. Energetics and HF vibrational frequency shifts from diffusion Monte Carlo calculations on additive and nonadditive potential-energy surfaces for n=1-12

The ground-state energies and HF vibrational frequency shifts of ArnHF clusters have been calculated on the nonadditive potential-energysurfaces (PESs) for n=2-7 and on the pairwise-additive PESs for the clusters with n=1-12, using the diffusionMonte Carlo (DMC) method. For n>3, the calculations have been performed for the lowest-energy isomer and several higher-lying isomers which are the closest in energy. They provide information about the isomer dependence of the HF redshift, and enable direct comparison with the experimental data recently obtained in helium nanodroplets. The agreement between theory and experiment is excellent, in particular, for the nonadditive DMC redshifts. The relative, incremental redshifts are reproduced accurately even at the lower level of theory, i.e., the DMC and quantum five-dimensional (rigid Arn) calculations on the pairwise-additive PESs. The nonadditive interactions make a significant contribution to the frequency shift, on the order of 10%–12%, and have to be included in the PESs in order for the theory to yield accurate magnitude of the HF redshift. The energy gaps between the DMC ground states of the cluster isomers are very different from the energy separation of their respective minima on the PES, due to the considerable variations in the intermolecular zero-point energy of different ArnHF isomers

PREOPERATIVE REHABILITATION OF COXARTHROSIS

59 žena i 26 muškaraca s artrozom kuka uključeno je u preoperativnu rehabilitaciju u trajanju od mjesec dana. Nakon rehabilitacije zabilježeno je poboljšanje funkcionalnog stanja kuka.59 females and 26 males with degenerative process of hip were included in preoperative rehabilitation in duration of one month. After that rehabilitation improvement of functional status of the hip was registrated

Infrared spectroscopy of small-molecule endofullerenes

Hydrogen is one of the few molecules which has been incarcerated in the molecular cage of C$_{60}$ and forms endohedral supramolecular complex H$_2$@C$_{60}$. In this confinement hydrogen acquires new properties. Its translational motion becomes quantized and is correlated with its rotations. We applied infrared spectroscopy to study the dynamics of hydrogen isotopologs H$_2$, D$_2$ and HD incarcerated in C$_{60}$. The translational and rotational modes appear as side bands to the hydrogen vibrational mode in the mid infrared part of the absorption spectrum. Because of the large mass difference of hydrogen and C$_{60}$ and the high symmetry of C$_{60}$ the problem is identical to a problem of a vibrating rotor moving in a three-dimensional spherical potential. The translational motion within the C$_{60}$ cavity breaks the inversion symmetry and induces optical activity of H$_2$. We derive potential, rotational, vibrational and dipole moment parameters from the analysis of the infrared absorption spectra. Our results were used to derive the parameters of a pairwise additive five-dimensional potential energy surface for H$_2$@C$_{60}$. The same parameters were used to predict H$_2$ energies inside C$_{70}$[Xu et al., J. Chem. Phys., {\bf 130}, 224306 (2009)]. We compare the predicted energies and the low temperature infrared absorption spectra of H$_2$@C$_{70}$.Comment: Updated author lis

Organic spelt production systems: Productive and financial performance in three orographic regions

A two-year field trial was conducted to study the effects of biohumus, biofertiliser, and soil conditioner application on spelt grain yield in different regions (plain, hilly, and mountainous regions) in Serbia. An analysis of economic efficiency indicators of spelt production in organic farming systems was also performed. The field experiment had a randomised complete block design with three replicates in each of the three regions. One winter spelt cultivar was also studied. The largest differences in spelt yield compared to control were found in the plain region in the biohumus + biofertiliser treatment (28.0%) and the hilly region in the organic fertiliser + zeolite treatment (28.8%). The differences in grain yield between control and treatment conditions in the mountain region were insignificant. Analysis of the economic effects of organic spelt production found a significantly lower gross margin in treatments with expensive organic fertilisers (3955.05 and 1104.75 € ha–1) than the control (5094.31 and 1833.85 € ha–1), leading to the conclusion that their application was not economically justified despite the increases in grain yield. The highest production costs (3569.71 € ha–1) were observed in treatments in the hilly region, resulting in the lowest benefit-cost ratio (0.1), while the greatest benefit-cost ratio was recorded in treatments in the mountainous region (2.1). Following the economic analysis results, a significant negative correlation between the benefit-cost ratio and the total production costs (r= –0.91**) was determined and a positive correlation between the gross margin and grain yield (r=0.66*). These results lead to the conclusion that the management strategy of spelt production in organic farming systems should be harmonised with the soil and agro-ecological characteristics of the region and directed at decreasing the costs and share of external inputs. In this case, organic spelt production can be economically profitable. © the Author(s), 2022

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

On Some Aspects of Rotationally Inelastic Polarized Molecule-Flat Surface Scattering

Polarized molecule-flat surface collisions are investigated for the case when the molecule is initially prepared in a certain rotational slate and when its rotational angular momentum j is aligned parallel to the surface. It is shown that the occurence of two rainbow peaks in M transitions, for the initial rotational quantum number different from zero, has a simple explanation when magnetic, mj transitions are explicitly considered. The essential features of the ~mj transition probability distribution are explained using a classical model

Clusters containing open-shell molecules. II. Equilibrium structures of ArnOH Van der Waals clusters (X2Π, n=1 to 15)

The equilibrium and low-lying isomeric structures of ArnOH (X2Π)clusters for n=1 to 15 are investigated by simulated annealing calculations. Potential energy surfaces are obtained by a pairwise-additive approach, taking into account the open-shell nature of OH X2Π and including spin-orbit coupling. It is found that the spin-orbit coupling suppresses the Jahn–Teller effect, and many of the clusters have high-symmetry structures(Cnν with n>2) which would be forbidden in the absence of spin-orbit coupling. The structures are generally similar to those previously found for the closed-shell systems ArnHF and ArnHCl, but different from those for the open-shell systems ArnNO and ArnCH. This is because Ar–OH (X2Π), like Ar–HF and Ar–HCl but unlike Ar–NO and Ar–CH, has a near-linear equilibrium structure.ArnOHclusters for n up to 6 have all Ar atoms in a single shell around OH. In the clusters with n=7 to 9, OH is under a pentagonal pyramid formed by six Ar atoms, while the others bind to its exterior, away from OH. For n=10 to 12, the minimum-energy structures have OH inside an Arn cage, which is essentially icosahedral for n=12 but has vacancies for n=10 and 11. For n>12, the extra Ar atoms begin to form a second solvation shell. The global minimum of ArnOH may be constructed from the minimum-energy structure of Arn+1 by replacing one Ar atom with OH

Clusters containing open-shell molecules: Minimum-energy structures and low-lying isomers of ArnCH (X2Π), n= 1 to 15.

The size evolution of the equilibrium structures of open-shell ArnCH (X2Π) Van der Waals clusters is investigated for n = 1 to 15. We describe a method for combining pair potentials for Ar–CH and Ar–Ar interactions to obtain potential energy surfaces for ArnCH clusters. For each cluster size considered, the global and a few energetically close local minima are calculated using simulated annealing followed by a direct minimization scheme. Ar2CH is found to have an unusually stable planar structure, which persists as a motif in larger ArnCH clusters and has a strong effect on their optimal geometries. The lowest-energy isomers of ArnCH with n = 3 to 11 have all Ar atoms in a shell around CH. The only exception is Ar4CH, where the fully solvated isomer is 3 cm−1 higher in energy than the optimal isomer with CH bound to the surface of the Ar4 tetrahedron. For n = 7 to 11, the minimum-energy structure of ArnCH derives from the global minimum of the Arn+1 cluster, by replacing the Ar atom at the bottom of the pentagonal bipyramid with CH. The lowest-energy structure of Ar12CH is that of the optimal icosahedral Ar13 cluster, with CH replacing one of the Ar atoms on the cluster surface. This structure supports the proposition based on the spectroscopic data, that for ArnCH clusters with about 10 to 50 Ar atoms CH resides on the surface of Arn