Dynamic 3D shape of the plantar surface of the foot using coded structured light:a technical report

The foot provides a crucial contribution to the balance and stability of the musculoskeletal system, and accurate foot measurements are important in applications such as designing custom insoles/footwear. With better understanding of the dynamic behavior of the foot, dynamic foot reconstruction techniques are surfacing as useful ways to properly measure the shape of the foot. This paper presents a novel design and implementation of a structured-light prototype system providing dense three dimensional (3D) measurements of the foot in motion. The input to the system is a video sequence of a foot during a single step; the output is a 3D reconstruction of the plantar surface of the foot for each frame of the input. Methods Engineering and clinical tests were carried out to test the accuracy and repeatability of the system. Accuracy experiments involved imaging a planar surface from different orientations and elevations and measuring the fitting errors of the data to a plane. Repeatability experiments were done using reconstructions from 27 different subjects, where for each one both right and left feet were reconstructed in static and dynamic conditions over two different days. Results The static accuracy of the system was found to be 0.3 mm with planar test objects. In tests with real feet, the system proved repeatable, with reconstruction differences between trials one week apart averaging 2.4 mm (static case) and 2.8 mm (dynamic case). Conclusion The results obtained in the experiments show positive accuracy and repeatability results when compared to current literature. The design also shows to be superior to the systems available in the literature in several factors. Further studies need to be done to quantify the reliability of the system in clinical environment

Energy-Degeneracy-Driven Covalency in Actinide Bonding

Evaluating the nature of chemical bonding for actinide elements represents one of the most important and long-standing problems in actinide science. We directly address this challenge and contribute a Cl K-edge X-ray absorption spectroscopy and relativistic density functional theory study that quantitatively evaluates An–Cl covalency in AnCl62– (AnIV = Th, U, Np, Pu). The results showed significant mixing between Cl 3p- and AnIV 5f- and 6d-orbitals (t1u*/t2u* and t2g*/eg*), with the 6d-orbitals showing more pronounced covalent bonding than the 5f-orbitals. Moving from Th to U, Np, and Pu markedly changed the amount of M–Cl orbital mixing, such that AnIV 6d- and Cl 3p-mixing decreased and metal 5f- and Cl 3p-orbital mixing increased across this series

Covalency in Metal-Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Advancing theories of how metal oxygen bonding influences metal oxo properties can expose new avenues for innovation in materials science, catalysis, and biochemistry. Historically, spectroscopic analyses of the transition metal peroxyanions, MO4x-, have formed the basis for new M O bonding theories. Herein, relative changes in M O orbital mixing in MO42- (M = Cr, Mo, W) and MO41- (M = Mn, Tc, Re) are evaluated for the first time by non-resonant inelastic X-ray scattering, X-ray absorption spectroscopy using fluorescence and transmission (via a scanning transmission X-ray microscope), and linear-response density functional theory. The results suggest that moving from Group 6 to Group 7 or down the triads increases M O e () mixing. Meanwhile, t2 mixing ( + ) remains relatively constant within the same Group. These unexpected changes in frontier orbital energy and composition are evaluated in terms of periodic trends in d orbital energy and radial extension

Covalency in Metal-Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Advancing theories of how metal oxygen bonding influences metal oxo properties can expose new avenues for innovation in materials science, catalysis, and biochemistry. Historically, spectroscopic analyses of the transition metal peroxyanions, MO4x-, have formed the basis for new M O bonding theories. Herein, relative changes in M O orbital mixing in MO42- (M = Cr, Mo, W) and MO41- (M = Mn, Tc, Re) are evaluated for the first time by non-resonant inelastic X-ray scattering, X-ray absorption spectroscopy using fluorescence and transmission (via a scanning transmission X-ray microscope), and linear-response density functional theory. The results suggest that moving from Group 6 to Group 7 or down the triads increases M O e () mixing. Meanwhile, t2 mixing ( + ) remains relatively constant within the same Group. These unexpected changes in frontier orbital energy and composition are evaluated in terms of periodic trends in d orbital energy and radial extension

Energy-Degeneracy-Driven Covalency in Actinide Bonding.

Evaluating the nature of chemical bonding for actinide elements represents one of the most important and long-standing problems in actinide science. We directly address this challenge and contribute a Cl K-edge X-ray absorption spectroscopy and relativistic density functional theory study that quantitatively evaluates An-Cl covalency in AnCl62- (AnIV = Th, U, Np, Pu). The results showed significant mixing between Cl 3p- and AnIV 5f- and 6d-orbitals (t1u*/t2u* and t2 g*/eg *), with the 6d-orbitals showing more pronounced covalent bonding than the 5f-orbitals. Moving from Th to U, Np, and Pu markedly changed the amount of M-Cl orbital mixing, such that AnIV 6d - and Cl 3p-mixing decreased and metal 5f - and Cl 3p-orbital mixing increased across this series

Determining Relative f and d Orbital Contributions to M–Cl Covalency in MCl₆^2– (M = Ti, Zr, Hf, U) and UOCl₅^– Using Cl K-Edge X‑ray Absorption Spectroscopy and Time-Dependent Density Functional Theory

Chlorine K-edge X-ray absorption spectroscopy (XAS) and ground-state and time-dependent hybrid density functional theory (DFT) were used to probe the electronic structures of <i>O</i>_<i>h</i>-MCl₆^2– (M = Ti, Zr, Hf, U) and <i>C</i>_4<i>v</i>-UOCl₅^–, and to determine the relative contributions of valence 3d, 4d, 5d, 6d, and 5f orbitals in M–Cl bonding. Spectral interpretations were guided by time-dependent DFT calculated transition energies and oscillator strengths, which agree well with the experimental XAS spectra. The data provide new spectroscopic evidence for the involvement of both 5f and 6d orbitals in actinide–ligand bonding in UCl₆^2–. For the MCl₆^2–, where transitions into d orbitals of <i>t</i>_2<i>g</i> symmetry are spectroscopically resolved for all four complexes, the experimentally determined Cl 3p character per M–Cl bond increases from 8.3(4)% (TiCl₆^2–) to 10.3(5)% (ZrCl₆^2–), 12(1)% (HfCl₆^2–), and 18(1)% (UCl₆^2–). Chlorine K-edge XAS spectra of UOCl₅^– provide additional insights into the transition assignments by lowering the symmetry to <i>C</i>_4<i>v</i>, where five pre-edge transitions into both 5f and 6d orbitals are observed. For UCl₆^2–, the XAS data suggest that orbital mixing associated with the U 5f orbitals is considerably lower than that of the U 6d orbitals. For both UCl₆^2– and UOCl₅^–, the ground-state DFT calculations predict a larger 5f contribution to bonding than is determined experimentally. These findings are discussed in the context of conventional theories of covalent bonding for d- and f-block metal complexes

Tetrahalide Complexes of the [U(NR)₂]²⁺ Ion: Synthesis, Theory, and Chlorine K‑Edge X‑ray Absorption Spectroscopy

Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U­(NR)₂X₄]^2– (X = Cl^–, Br^–) and non-coordinating NEt₄⁺ and PPh₄⁺ countercations are reported. In general, these compounds can be prepared from U(NR)₂I₂(THF)_<i>x</i> (<i>x</i> = 2 and R = ^<i>t</i>Bu, Ph; <i>x</i> = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl^–, the [U­(NMe)₂]²⁺ cation also reacts with Br^– to form stable [NEt₄]₂[U­(NMe)₂Br₄] complexes. These materials were used as a platform to compare electronic structure and bonding in [U­(NR)₂]²⁺ with [UO₂]²⁺. Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U–Cl bonding interactions in [PPh₄]₂[U­(N^<i>t</i>Bu)₂Cl₄] and [PPh₄]₂[UO₂Cl₄]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7–10% per U–Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands

Tetrahalide Complexes of the [U(NR)₂]²⁺ Ion: Synthesis, Theory, and Chlorine K‑Edge X‑ray Absorption Spectroscopy

Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U­(NR)₂X₄]^2– (X = Cl^–, Br^–) and non-coordinating NEt₄⁺ and PPh₄⁺ countercations are reported. In general, these compounds can be prepared from U(NR)₂I₂(THF)_<i>x</i> (<i>x</i> = 2 and R = ^<i>t</i>Bu, Ph; <i>x</i> = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl^–, the [U­(NMe)₂]²⁺ cation also reacts with Br^– to form stable [NEt₄]₂[U­(NMe)₂Br₄] complexes. These materials were used as a platform to compare electronic structure and bonding in [U­(NR)₂]²⁺ with [UO₂]²⁺. Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U–Cl bonding interactions in [PPh₄]₂[U­(N^<i>t</i>Bu)₂Cl₄] and [PPh₄]₂[UO₂Cl₄]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7–10% per U–Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands