The prognosis for return to athletic function for Thoroughbred racehorses in Hong Kong with injuries to the palmaroproximal aspect of the metacarpus diagnosed using low-field magnetic resonance imaging.

OBJECTIVE: To evaluate and compare the prognosis for Thoroughbred racehorses to return to galloping and racing with injuries to the palmaroproximal metacarpus diagnosed with MRI. ANIMALS: 29 flat racing Thoroughbreds at the Hong Kong Jockey Club that underwent MRI between 2014 and 2022. METHODS: Clinical, radiographic, ultrasonographic, and MRI reports were collected from veterinary clinical records, and these were combined with training and racing data. Horses were categorized on the basis of MRI diagnosis: (1) proximal suspensory ligament (PSL) involvement only, (2) PSL and concurrent proximal third metacarpal (MC3) bone involvement, and (3) proximal MC3 bone involvement only. The following were compared for prognosis for return to athletic function: return to galloping or racing, and reinjury. RESULTS: Overall, the prognosis for return to athletic function was fair, with 92% (22/24; P = .53) and 67% (16/24; P = .73) of horses returning to galloping and racing, respectively. There was a relatively low reinjury rate, with 18% (4/22) of horses reinjuring. Horses with concurrent injury to both the PSL and proximal MC3 bone (Category 2) took longer to return to gallop (median, 116; IQR, 100.5 to 160), when compared with horses having only PSL injury (median, 69; IQR, 43 to 80; P = .04). Of the 4 horses that reinjured, 3 (75%) were horses in Category 2. CLINICAL RELEVANCE: The findings from this study suggest that injuries involving both PSL and proximal MC3 bone concurrently require a longer rehabilitation period than those with PSL involvement alone.

Photoelectron spectra and structure of the Mnn(-) anions (n = 2-16).

Photoelectron spectra of the Mnn(-) anion clusters (n = 2-16) are obtained by anion photoelectron spectroscopy. The electronic and geometrical structures of the anions are computed using density functional theory with generalized gradient approximation and a basis set of triple-ζ quality. The electronic and geometrical structures of the neutral Mnn clusters have also been computed to estimate the adiabatic electron affinities. The average absolute difference between the computed and experimental vertical detachment energies of an extra electron is about 0.2 eV. Beginning with n = 6, all lowest total energy states of the Mnn(-) anions are ferrimagnetic with the spin multiplicities which do not exceed 8. The computed ionization energies of the neutral Mnn clusters are in good agreement with previously obtained experimental data. According to the results of our computations, the binding energies of Mn atoms are nearly independent on the cluster charge for n > 6 and possess prominent peaks at Mn13 and Mn13(-) in the neutral and anionic series, respectively. The density of states obtained from the results of our computations for the Mnn(-) anion clusters show the metallic character of the anion electronic structures.

Gas phase analogs of stable sodium-tin Zintl ions: anion photoelectron spectroscopy and electronic structure.

Mass spectrometry and photoelectron spectroscopy together with first principles theoretical calculations have been used to study the electronic and geometric properties of the following sodium-tin, cluster anion/neutral cluster combinations, (Na(n)Sn(4))(-)/(Na(n)Sn(4)), n = 0-4 and (NaSn(m))(-)/(NaSn(m)), m = 4-7. These synergistic studies found that specific Zintl anions, which are known to occur in condensed Zintl phases, also exist as stable moieties within free clusters. In particular, the cluster anion, (Na(3)Sn(4))(-) is very stable and is characterized as (Na(+))(3)(Sn(4))(-4); its moiety, (Sn(4))(-4) is a classic example of a Zintl anion. In addition, the cluster anion, (NaSn(5))(-) was the most abundant species to be observed in our mass spectrum, and it is characterized as Na(+)(Sn(5))(2-). Its moiety, (Sn(5))(2-) is also known to be present as a Zintl anion in condensed phases.

Electronic and geometrical structure of Mn13 anions, cations, and neutrals.

We have computed the electronic and geometrical structures of thirteen atom manganese clusters in all three charge states, Mn(13) (-), Mn(13) (+), and Mn(13) by using density functional theory with the generalized gradient approximation. Our results for Mn(13) (-) are compared with our anion photoelectron spectrum of Mn(13) (-), published in this paper. Our results for Mn(13) (+) are compared with the previously published photoionization results of Knickelbein [J. Chem. Phys. 106, 9810 (1997)]. There is a good agreement between theoretical and experimental values of ionization and electron attachment energies.

The ionic KAl13 molecule: a stepping stone to cluster-assembled materials.

Theoretical calculations by Khanna and Jena predicted KAl(13) to be an ionically bonded, cluster-assembled "diatomic molecule," i.e., K(+)Al(13) (-). We have conducted both mass spectral and anion photoelectron spectroscopic studies on KAl(n) (-), finding a "dip" at n=13 in both their mass spectrum and in their electron affinity versus n trend. While these largely qualitative results are consistent with KAl(13) being a salt, they can also be explained in terms of the shell model and thus, by themselves, are not conclusive. Quantitative comparisons between calculated photodetachment transition energies and the photoelectron spectrum of KAl(13) (-), however, allow a strong case to be made for ionic bonding in KAl(13). As a prototype for ionic bonding involving intact Al(13) (-) subunits, KAl(13) may be a stepping stone toward forming ionic, cluster-assembled materials.