Crystal structure of a methanol solvate of a macrocycle bearing two flexible side-arms

Di-tert-butyl N,N′-{[13,15,28,30,31,33-hexaethyl-3,10,18,25,32,34-hexaazapentacyclo[25.3.1.15,8.112,16.120,23]tetratriaconta-1(31),3,5,7,9,12(33),13,15,18,20,22,24,27,29-tetradecaene-14,29-diyl]bis(methylene)}dicarbamate methanol disolvate, C52H72N8O4·2CH3OH, was found to crystallize in the space group P21/c with one half of the macrocycle (host) and one molecule of solvent (guest) in the asymmetric unit of the cell, i.e. the host molecule is located on a crystallographic symmetry center. Within the 1:2 host–guest complex, the solvent molecules are accommodated in the host cavity and held in their positions by O—H...N and N—H...O bonds, thus forming ring synthons of graph set R 2 2(7). The connection of the 1:2 host-guest complexes is accomplished by C—H...O, C—H...N and C—H...π interactions, which create a three-dimensional supramolecular network.

Ammonium tantalum oxide fluorides: new features of dynamic disorder

Ammonium fluoride salts of seven- and eight-coordinated tantalum were grown in the form of well shaped single crystals at different pH of solutions, and their crystal structures were determined by X-ray diffraction. The first one, (NH4)3TaOF6, belongs to elpasolite-type structure (Fm{\overline 3}m, Z = 4) and is characterized by strong dynamic disorder. The ligand atoms (O and F) are each distributed in three positions (one 24e and two 96j). The tantalum atom is seven-coordinated in the form of a pentagonal bipyramid (PB) and occupies the 4a position without leaving the symmetry center of the polyhedron during its fast reorientation. One of the ammonium groups is tetrahedrally disordered (the nitrogen atom is shifted from the 8c into the 32f site), while the other group in the 4b site forms eight spatial orientations due to disordering of hydrogen atoms in the 96k and 32f positions. Strong dynamic disorder of [TaOF6]3– as a flexible unit is reflected in the IR spectrum at 736 cm−1 and in the 19F MAS NMR spectrum at −51 ppm, indicating a state with synchronous stretching vibrations of Ta—O and Ta—F bonds. Two double ammonium fluoride salts of tantalum, which are formed concomitantly, differ slightly in composition but their crystal structures contain the same polyhedra in the form of a mono-capped trigonal prism (CTP or TPRS-7) and a distorted cube (CU or CU-8) with one vacant vertex. The latter tantalum polyhedron is detected for the first time. The CU polyhedron in one of the modifications of the tantalum double salt splits into two CTPs during a phase transition with decreasing temperature. The presence of oxygen in the compounds is confirmed by vibrational spectroscopy.

Two-Dimensional Advection–Diffusion Process with Memory and Concentrated Source

Two-dimensional advection–diffusion processes with memory and a source concentrated in the symmetry center of the domain have been investigated. The differential equation of the studied model is a fractional differential equation with short-tail memory (a differential equation with Caputo–Fabrizio time-fractional derivatives). An analytical solution of the initial-boundary value problem has been determined by employing the Laplace transform and double sine-Fourier transforms. A numerical solution of the studied problem has been determined using finite difference approximations. Numerical simulations for both solutions have been carried out using the software Mathcad.

BaWO4:Ce Single Crystals Codoped with Na Ions

Single crystals of BaWO4, BaWO4: 0.5 at. % Ce; BaWO4: 1 at. % Ce; BaWO4: 0.5 at. % Ce, 1 at. % Na; and BaWO4: 1 at. % Ce, 2 at. % Na were grown from an inductively heated iridium crucible by the Czochralski method on a Malvern MSR4 puller. They were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy at helium temperatures. One isolated center of high (D2d or S4) symmetry was found and two or more other centers of lower symmetry were identified, depending on crystal doping. From the fitting using the EPR-NMR program, the following parameters of g-matrix for the high symmetry center were found: gx = 1.505, gy = 1.505, and gz = 2.731. The linewidth vs. temperature revealed an increasing exponential tendency with increasing temperature. It showed one phonon at the lower temperatures and a Raman + Orbach effect at the higher temperatures. Radioluminescence and pulse height spectra showed rather poor scintillation properties, without any contribution from cerium emission.

An Intercenter Comparison of Nasolabial Appearance Including a Center Using Nasoalveolar Molding

Objective: To compare nasolabial appearance outcomes of patients with complete unilateral cleft lip and palate (CUCLP) in preadolescence from 4 cleft centers including a center using nasoalveolar molding (NAM) and primary nasal reconstruction. Design: Retrospective cohort study. Setting: Four cleft centers in North America. Patients: 135 subjects with repaired CUCLP. Methods: Frontal and profile facial pictures were assessed using the Asher-McDade rating scale. Intra- and interrater reliability were tested using weighted Kappa statistics. Median scores by center were compared with Kruskal-Wallis statistics. Results: Intrarater reliability scores were moderate to good. Interrater reliability scores were moderate. Significant differences ( P < .05) among centers were found. For nasal form, center G (median = 2.83) had better scores than centers C and D (C median = 3.33, D median = 3.17). For nose symmetry, center G had better scores (median = 2.33) than all other centers (B median = 2.67, C median = 2.83, D median = 2.83). For vermillion border, center G had better scores (median = 2.58) than centers B and C (B median = 3.17, C median = 3.17). For nasolabial profile, center G (median score = 2.67) had better scores than center C (median = 3.00). For total nasolabial score, center G (median = 2.67) had better scores than all other centers (B median = 2.83, C median = 3, D median = 2.83). Conclusion: The protocol followed by center G, the only center that performed NAM and primary nasal reconstruction, produced better results in all categories when compared to center C, the only center that did not perform presurgical orthopedics or lip/nose revisions. When compared to centers that performed traditional presurgical orthopedics and surgical revisions (B and D), center G was not consistently better in all categories. As with other uncontrolled, retrospective intercenter studies, it is not possible to attribute the outcomes to a specific protocol component.

A Precise Algorithm for Known Spherical Marker Position Retrieval Using an Ideal Pinhole Camera in a Diffuse Light Scene

The exact marker image was computed for various positions in the workspace and for each image was computed back the approximation of the marker position based on it. The position computation used the symmetry of the scene and the particular characteristics of the ellipse marker projection. Was established that the center of symmetry of the marker projection is different than the projection of the marker center itself and the the relation between two was found using the Dandeline Spheres. For a given marker radius the ratio between the area of the right cone base that contains the marker center projection and the area of the marker projection was expressed as a law based only on the angle of the line passing through the focal point and the symmetry center of the marker projection and the view axis. Based on all these intermediary results was obtained an algorithm with a precision under 0.04 mm in sagital plane, and under 0.1 mm on the depth view axis with a modest 1920x1680 camera resolution.

Multivariate symmetric refinable functions and function vectors

For any symmetry group [Formula: see text], any appropriate matrix dilation (compatible with [Formula: see text]) and any appropriate symmetry center [Formula: see text] we give an explicit method for the construction of [Formula: see text]-symmetric with respect to the center [Formula: see text] refinable masks which have sum rule of an arbitrary order [Formula: see text]. Moreover, we give a description of all these masks. For any symmetry group [Formula: see text], any appropriate matrix dilation (compatible with [Formula: see text]) and any appropriate row of symmetry centers [Formula: see text] we give two explicit methods for the construction of [Formula: see text]-symmetric with respect to the row of centers [Formula: see text] refinable matrix masks which have sum rule of an arbitrary order [Formula: see text]. A description of all such matrix masks is also presented.

Structural basis of Dscam1 homodimerization: Insights into context constraint for protein recognition

The Drosophila neural receptor Dscam1 (Down syndrome cell adhesion molecule 1) plays an essential role in neuronal wiring and self-avoidance. Dscam1 potentially encodes 19,008 ectodomains through alternative RNA splicing and exhibits exquisite isoform-specific homophilic binding, which makes it an exceptional example for studying protein binding specificity. However, structural information on Dscam1 is limited, which hinders illumination of the mechanism of Dscam1 isoform-specific recognition. Whether different Dscam1 isoforms adopt the same dimerization mode remains a subject of debate. We present 12 Dscam1 crystal structures, provide direct evidence indicating that all isoforms adopt a conserved homodimer geometry in a modular fashion, identify two mechanisms for the Ig2 binding domain to dispel electrostatic repulsion during dimerization, decode Ig2 binding specificity by a central motif at its symmetry center, uncover the role of glycosylation in Dscam1 homodimerization, and find electrostatic potential complementarity to help define the binding region and the antiparallel binding mode. We then propose a concept that the context of a protein may set restrictions to regulate its binding specificity, which provides a better understanding of protein recognition.

Wireless Multi-Axial Force Sensing Shoe for Gait Abnormalities Monitoring

Measurements of sequential Ground Reaction Force (GRF) can provide quite useful information for monitoring of gait abnormalities during activities in daily life. Measuring sequential GRF in conventional approach using force plates is difficult due to the limited number of force plates. Therefore, we developed a fully untethered GRF sensing system having the low height (12 mm) and the capability of sensing simultaneously shear and normal GRF. The biaxial force sensing shoe showed the excellent repeatability (0.6 %) under long-term periodic loading condition for two hours. Comparison experiments with commercially available film type force sensors, FSR (Interlink) and Flexiforce (Tekscan), were performed under walking condition for twenty minutes. Owing to the high repeatability of the proposed system, variabilities of swing time and stance time of user were investigated with two subjects, a healthy subject and a foot-drop patient. We suggested three diagnostic measures in consideration of conventional approaches — variability for gait symmetry, center of pressure distribution for balance, and ratio of shear and normal GRFs for foot pronation.