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Online Minimum-Jerk Trajectory Generation

Robotic trajectory generation is reformulated as a controller design problem. For minimum-jerk trajectories, an optimal controller using the Hamilton-Jacobi-Bellman equation is derived. The controller instantaneously updates the trajectory in a closed-loop system as a result of the changes in the reference signal. The resulting trajectories coincide with piece-wise fifth-order polynomial trajector

Treatment of radius or ulna fractures in the elderly : A systematic review covering effectiveness, safety, economic aspects and current practice

Background The objective of the present study was to evaluate effectiveness, complications and cost-effectiveness of any surgical or non-surgical treatment for radius or ulna fractures in elderly patients. Secondary objectives were to analyze present treatment traditions of distal radius fractures (DRF) in Sweden and to calculate resource usage for its treatment. Methods and findings The assessmen

α-Cd13-xSb10 - The devil is in the details

A detailed study of the structure of α-Cd13-xSb 10 was performed using a high quality single crystal obtained from a cadmiumrich melt. The study clearly shows that this sample is cadmium-deficient, and should more properly be labelled α-Cd13-xSb10, but whether this is true in general for this phase, or if it is an effect of the precise conditions of synthesis remains unclear. Like for the similar

Rez4Si7, first in a new MoSi2-based family of 14-electron phases

A study was conducted to investigate the geometrical and electronic connections of Re4Si7 to the rich structural chemistry of the Nowotny Chimmney Ladder phases (NCL). Re4Si7 was prepared by arc-melting a pressed pellet of Re and Si in a stoichiometric ratio, sealing the resulting globule in an excavating quartz tube, and annealing the sample in a muffle furnace. It was found that NCLs were interm

Modulations in the onoratoite system

The iodide form of the mineral onoratoite was synthesized, and like the Cl and Br based analogues, it displays super structure ordering, but for the iodide, the super structure is clearly incommensurate. Due to the poor quality of crystals attainable, the structure was solved by converting the solution of the Cl analogue to a super space formalism, and then using the structural elements from this

Structural model for octagonal quasicrystals derived from octagonal symmetry elements arising in β-Mn crystallization of a simple monatomic liquid

While performing molecular-dynamics simulations of a simple monatomic liquid, we observed the crystallization of a material displaying octagonal symmetry in its simulated diffraction pattern. Inspection of the atomic arrangements in the crystallization product reveals large grains of the β-Mn structure aligned along a common fourfold axis, with 45° rotations between neighboring grains. These 45° r

Helical chains of [MO5Cl] octahedra - Three compounds in the new family AEM2Te3O8Cl2 (AE = Ca, Sr and M = Co, Ni)

The compounds CaCo2Te3O8Cl2, SrCo2Te3O8Cl2 and SrNi2Te3O8Cl2 were synthesized via solid-gas reactions and investigated using single-crystal X-ray diffraction. While the compound CaCo2Te3O8Cl2 formed large enough single crystals to allow for a detailed structural analysis, crystals of the Sr-containing compounds yielded evidence that they are isostructural. CaCo2Te3O8Cl2 crystallizes in the monocli

Metastable Cd4Sb3 : A complex structured intermetallic compound with semiconductor properties

The metastable binary intermetallic compound Cd4Sb3 was obtained as polycrystalline ingot by quenching stoichiometric Cd-Sb melts and as mm-sized crystals by employing Bi or Sn fluxes. The compound crystallizes in the monoclinic space group Pn with a = 11.4975(5) Å, b = 26.126(1) Å, c = 26.122(1) Å, β = 100.77(1)°, and V = 7708.2(5) A,̊3. The actual formula unit of Cd4Sb3 is Cd13Sb10 and the unit

Anomalous low-temperature behavior of the Co dimers in the oxo-halide CoSb2O3Br2

We report the synthesis, crystal structure determination, magnetic and low-temperature structural properties of a new cobalt antimony oxo-bromide. CoSb2O3Br2 crystallizes in the triclinic crystal system, space group P-1, with the following lattice parameters: a = 5.306(3) Å, b = 7.812(4) Å, c = 8.0626(10) Å, α = 88.54(3)°, β= 82.17(3)°, γ = 80.32(4)°, and Z = 2. The crystal structure was solved fr

Single-crystal X-ray study of Ba2Cu2Te 4O11Br2 and its incommensurately modulated superstructure companion

Compounds containing lone-pair elements such as TeIV are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features - Ba2Cu2Te 4O11Br2 (I) and Ba2Cu 2Te4O11-δ(OH)2δBr 2 (II, δ ≈ 0.57) - as members of the AE-M-Te-O-X (AE = alkaline-earth metal, M = transition metal

Vacancy-ordering effects in AlB2-type ErGe2 - X (0.4 < x ≤ 0.5)

In the Er-Ge system, the compostion range ErGe2 to Er2Ge3 has been investigated. Eight samples were produced by arc melting of the elements, and analyzed using X-ray powder diffraction. Nine crystal structures were found to be present in the samples. The structures are described as a homologous series and presented within the superspace formalism using the superspace group X2/m(α0γ)0s, X represent

All the disorder mechanisms in the 13:58 phases come together. Out of the modulated confusion rises the remarkable phase Ce12.60Cd 58.68(2)

The compound Ce12.60Cd58.68(2) is a metrically commensurate representative of the incommensurately modulated phase Ce 13Cd57+δ. It is most likely a lock-in phase. The structure, which was solved using seeding of the modulation from those positions most affected as well as direct solution by charge flipping, represents a rare case of ordering in a family of structures where disorder is the rule. Th

Synthesis, structure, and bonding of Sc4MgxCu 15 - xGa∼7.5 (x = 0, 0.5). Two incommensurately modulated scandium substitution derivatives of cubic Mg 2Cu6Ga5

The substitution of scandium for magnesium in Mg2Cu 6Ga5 (Mg2Zn11-type) yields an irrational superstructure phase that includes the refined compositions, Sc 4Mg0.50(2)Cu14.50(2)Ga7.61(2) and Sc4Cu14.76(2)Ga7.51(2). These crystallize in Cmmm, a = ∼8.31 Å, b = ∼21.72 Å, c = ∼8.30 Å. The structures feature Sc2 dimers, Cu6 octahedra, a 3D CuGa (Cu12Ga2) framework, and arachno gallium-centered Cu 4Ga6

Quasicrystal approximant Ho13Zn 58 + δ (δ ≈ 0.6) : An incommensurate modulated tunnel structure

In a systematic study of the binary quasicrystal approximants RE13Zn58 (RE = rare earth elements) system, single crystals of Ho13Zn58 + have been prepared. It is unique among family members of the RE13Zn58 system in that it shows a modulated superstructure ordering. Satellite reflections observed in single crystal X-ray diffraction pattern indicate the presence of a one-dimensional lattice distort

Single-crystal growth and structure determination of misfit layer oxide [Sr2TlO3][CoO2]1.77

We have synthesized single crystals of the misfit layer cobaltate [Sr2TlO3][CoO2]1.77 and determined its crystal structure by the means of X-ray single-crystal diffraction (XRSD) and transmission electron microscopy. The synthesis took place by spontaneous crystallization from an oxide melt at high gaseous pressure. The structure is described by two monoclinic subsystems, which share the unit cell

Low-temperature structural transitions in the phonon-glass thermoelectric material β-Zn 4 Sb 3 : Ordering of Zn interstitials and defects

The low-temperature phase transitions of thermoelectric Zr 4 Sb 3 have been characterized using singlecrystal X-ray diffraction, electrical resistance, and thermal conductivity measurements. Room-temperature stable, disordered β-Zn 4 Sb 3 undergoes a phase transition at 254 K to ordered α-n 4 Sb 3 , which has an ideal composition Zn 4 Sb 10 . Below 235 K, a second low-temperature phase (α′-Zn

The crystal structure of CuSb2O3Br : Slabs from cubic Sb2O3 interspersed between puckered hexagonal CuBr-type layers

The new compound CuSb2O3Br crystallize in the monoclinic space group Cc. The unit cell parameters are a=7.9189(15)Å, b=13.7105(10)Å, c=19.048(2)Å, β=90°, Z=16. The crystal structure is solved from single crystal data, R=0.0490. The compound show a layered structure with slabs from cubic Sb2O3 interspersed in between puckered layers of CuBr. The Sb(III) atoms have tetrahedral [SbO3E] coordination w

New Sr-substituted niobium-based misfit layer sulfides

Two series of [(Ln1/3Sr2/3S)1.5]1.15NbS2and (Ln1-xSrxS)1+yNbS2misfit layer sulfides have been synthesized and studied by X-ray powder and single crystal diffraction, electron diffraction, and EDX-analysis. The [(Sm1/3Sr2/3S)1.5]1. 15NbS2compound belongs to the 1.5Q/1H homologue type where the Sr-cations are mainly located at the exterior of the Q-slab whereas Sm preferably occupy the positions at

The structures of X2[(Mo6Cl8)Cl 6]·nH2O, X=NH4, K, Rb, Cs

The title compounds were synthesized from MoCl2 and the appropriate commercial chlorides and their structures were solved by a combination of single crystal X-ray diffraction analysis and theoretical methods. The NH4, K and Rb compounds are essentially isostructural, and crystallize in space group Ia (No. 9) with the cell parameters (in Å) a=9.173(1), b=14.986(2), c=17.505(3), β=92.94(2)°(NH4); a=

Site occupancy wave and charge density wave in the modulated structure of Nd0.6Gd0.4Se1.85

Single crystals of Nd0.6Gd0.4Se1.85 have been prepared by chemical transport reactions starting from pre-annealed powder samples. Satellite reflections observed in X-ray and electron diffraction experiments indicate the presence of a two-dimensional lattice distortion. The origin of this is a site occupancy wave and, coupled to this, a charge density wave in the planar selenium layer of this compo