The trunk is frequently modelled as one fixed segment ignoring possible multi-segmental contributions during manual handling. This study compared segmental trunk motion in a young and older ...population during a lifting task. Twelve elderly and 19 young subjects repeatedly lifted a 5 kg box from bench to shelf under two stance conditions. Displacement and angular trunk segment kinematics were recorded with an electromagnetic tracker system and then analysed. The elderly subjects displayed significantly increased pelvic and trunk displacement and significantly reduced pelvic and lower thorax (T10-L1) range of motion in both stance conditions. Upper thorax (C7-T10) motion was at times greater than lumbar motion and opposite to the lower segments and was related to the task while the lower segments contributed to both equilibrium and task requirements. Decreased segmental trunk angular kinematics may contribute to increased displacement kinematics and place the elderly at increased risk of injury and falling. The pelvis, lumbar spine, low thorax (T10-L1), upper thorax (C7-10) contributed uniquely and synchronously to trunk (C7-S2) mechanics during a lifting task. Reduced angular kinematics of the pelvis and low thorax contributed to increased displacement kinematics and hence increased the risk of falling in the elderly compared to the young. Investigations of trunk mechanics should include multi-segment analysis.
The synthesis of a new hexapyrrolic expanded porphyrin, hexaphyrin (1.0.1.0.0.0) (
1), that was found to form unique complexes of the actinide cations neptunyl (NpO
2
+
) and uranyl (UO
2
2+
) was ...recently reported (Sessler et al., Angew. Chem., Int. Ed. Engl. 40 (2001) 591). The present study was undertaken in an effort to generalize these findings and involves an analysis of the neptunyl (NpO
2
+
) and plutonyl, (PuO
2
+
) coordination chemistry of several other expanded porphyrin systems, including those previously reported as having formed uranyl (UO
2
2+
) cation complexes, in particular amethyrin (24hexaphyrin(1.0.0.1.0.0),
2), pentaphyrin, (22pentaphyrin(1.1.1.1.1),
4), and the Schiff base macrocycle, alaskaphyrin (
5). This study was broadened to include the Schiff base ligand
6 (grandephyrin) and its previously unreported uranyl (UO
2
2+
) complex. Within moments of addition of a neptunium(VI) source to methanol solutions of the expanded porphyrins
1,
2,
4,
5 and
6, dramatic changes in the UV–Vis spectra are observed that are consistent with formation of a neptunyl complex and, in several cases, oxidation of the macrocycle. Similar changes were also observed when hexaphyrin (
1), pentaphyrin (
4), alaskaphyrin (
5), and grandephyrin (
6) were exposed to PuO
2
2+
. Corroborative changes are also observed in the associated
1H NMR spectra and in those portions of the electronic spectrum associated with the actinide cations. Although the formation of the proposed neptunyl and plutonyl complexes could not be substantiated by X-ray diffraction methods, the solid-state structure of the uranyl complex formed from
6 was elucidated and is presented in this report.
The interactions, characterized by spectroscopic means, between the actinide cations, neptunyl (NpO
2+) and plutonyl (PuO
2
+
), and several expanded porphyrins including amethyrin, (24hexaphyrin(1.0.0.1.0.0)), pentaphyrin (22pentaphyrin(1.1.1.1.1)), hexaphyrin (1.0.1.0.0.0), and the related Schiff base, alaskaphyrin are described. The synthesis of a new Schiff base ligand, grandephyrin (shown at right) and the single crystal X-ray diffraction structure of its uranyl (UO
2
2+
) complex is also presented.
Electrochemical cells are a key technology for a sustainable energy future. Here experiments are presented verifying a new type of cell: the asymmetric membrane concentration cell (AMCC). This cell ...charges using a unique mechanism: its concentration difference is generated internally by a chemically-asymmetric membrane that drives anisotropic diffusion of electrolyte ions, rather than being provided by an external source. This self-charging mechanism confers potential advantages over other cell types, including improved thermodynamic efficiency, compactness, and economy. For this study, custom membranes were developed to concentrate hydrogen and chloride ions; these were installed in single and series arrangements; the solutions from the latter were incorporated into a chloride-ion concentration cell. Experimental results agree well with theoretical predictions developed in a companion article 1. Based on these findings, suggestions are made for improving the performance of the AMCC.
Pu L3 XAFS measurements show that the excess oxygen in single phase PuO2+ x occurs as oxo groups with Pu−O distances of 1.83−1.91 Å. This distance and the energy of the edge (via comparison with a ...large number of related compounds) are more consistent with a Pu(IV/V) than a Pu(IV/VI) mixture. Analogous to Pu(IV) colloids, although the Pu−Pu pair distribution remains single site even when it shows substantial disorder, the Pu−O distribution can display a number of additional shells at specific distances up to 3.4 Å even in high fired materials when no oxo groups are present, implying intrinsic H+/OH-(/H2O). The number of oxo atoms increases when samples are equilibrated with humid air at ambient temperature, indicating that the Pu reactivity in this solid system differs notably from that of isolated complexes and demonstrating the importance of nanoscale cooperative phenomena and total free energy in determining its chemical properties.
Pu L3 X-ray near edge absorption spectra for Pu(0−VII) are reported for more than 60 chalcogenides, chlorides, hydrates, hydroxides, nitrates, carbonates, oxy-hydroxides, and other compounds both as ...solids and in solution, and substituted in zirconolite, perovskite, and borosilicate glass. This large database extends the known correlations between the energy and shape of these spectra from the usual association of the XANES with valence and site symmetry to higher order chemical effects. Because of the large number of compounds of these different types, a number of novel and unexpected behaviors are observed, such as effects resulting from the medium and disorder that can be as large as those from valence.
In the stream-dwelling isopod, Lirceus fontinalis, mating contests between males and females occur prior to pair formation. We examined the relative contribution of male preference and female ...resistance to contest outcomes. We first quantified male and female behavior during typical mating interactions and examined the relationship between time until molt (TTM) and mating outcomes. We then examined the role of male preference and female resistance in determining mating outcomes when females differed in molt type (growth, egg deposition) and appeared to differ in TTM (due to hormone applications). Both male preference and female resistance contributed to different components of the mating sequence but female resistance ultimately determined whether or not pair formation occurred. Males expressed a preference for females that appeared to be close to molt, using variation in levels of molt hormone as a cue. However, males did not discriminate between females based on molt type.
Binding within the first coordination sphere of the dioxoactinide ion is observed for the crown ether ligand in the complex ion NpO2(18crown‐6)+ 1, which is readily formed on adding 18crown‐6 to an ...aqueous solution of NpO2+ or NpO22+ in dilute HClO4 or CF3SO3H. The structure of the complex was confirmed by the X‐ray structure analysis and spectroscopic data of 1ClO4.
Reaction of LnN(SiMe
3)
2
3 (Ln=Sm, Nd) with one equivalent of the bulky heptadentate Schiff-base ligand NCH
2CH
2NCH(2-OH-3,5-
t-Bu
2C
6H
2)
3 (
1) resulted in formation of the 7-coordinate ...complexes {NCH
2CH
2NCH(2-O-3,5-
t-Bu
2C
6H
2)
3}Ln (Ln=Sm (
2), Nd (
3)). X-ray diffraction studies of
2 and
3 reveal isostructural hemi-toluene solvate complexes in which the N
4O
3 donor atom set of the ligand defines a slightly distorted capped octahedral geometry about the metal center. Ln–N bond lengths are of two types
—
an average of 2.556(3) Å (
2) (2.587(5) Å (
3)) to the three imine nitrogens, and a significantly longer interaction of 2.818(4) Å (
2) (2.811(5) Å (
3)) with the apical amine nitrogen. Ln–O distances lie in the range 2.218(3)–2.232(4) Å for
2 and 2.241(6)–2.248(4) Å for
3.
