DYNAMIC SIMULATION OF TENNIS RACKET AND STRING

oai:ojs.ojs.ub.uni-konstanz.de:article/95This study is based on the finite element method, a computer simulation method, to analyse the dynamic property of tennis racket and string. A three-dimensional model was created in Solidwork according to the geometry of a mid-size graphite tennis racket. Recording the speed and position data of ball and string collision. Using Ansys to calculate the modal frequency and shape, the results illustrate that the fixed racket’s model frequency was smaller than free condition, and the string’s vibration character was meaningful to both devise and fix the damper

A NOVEL INTER-PERSONAL AREA NETWORK COMMUNICATION MECHANISM FOR LARGE-SCALE LOW-POWER AND LOSSY NETWORKS

For large-scale Low-Power and Lossy Networks (LLNs), communications between nodes in different Personal Area Networks (PANs) (i.e., inter-PAN communications) typically have to traverse long routing paths, even for cases in which two nodes may be located physically close to each other. Techniques herein provide a novel mechanism to improve inter-PAN communications by utilizing the nodes that are located at the boundary of PANs

(5,5′-Dimethyl-2,2′-bipyridine-κ2 N,N′)(1-naphthyl­acetato-κO)(1-naphthyl­acetato-κ2 O,O′)zinc hemihydrate

In the title compound, [Zn(C12H9O2)2(C12H12N2)]·0.5H2O, the water mol­ecule lies on a twofold rotation axis. The ZnII atom is coordinated by three O atoms from two 1-naphthyl­acetate ligands, one monodentate and the other asymmetric bidentate chelate, and two N atoms from a 5,5′-dimethyl-2,2′-bipyridine ligand, giving an irregular environment. In the crystal, the complex mol­ecules are inter­linked through the water mol­ecule by O—H⋯Ocarboxyl­ate hydrogen bonds, together with weak C—H⋯O and bipyridine ring π–π stacking inter­actions [ring centroid separation = 3.761 (2) Å], giving a two-dimensional network structure

Bis(2,4-dichloro­phen­oxy­acetato-κ2 O 1,O 1′)(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)cobalt(II)

In the title compound, [Co(C8H5Cl2O3)(C12H12N2)], the CoII atom, lying on a twofold rotation axis, is coordinated by four O atoms from two chelating 2,4-dichloro­phen­oxy­acetate ligands and two N atoms from a 5,5′-dimethyl-2,2′-bipyridine ligand, displaying a distorted octa­hedral geometry. A three-dimensional supra­molecular structure is formed through inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions between the pyridine and benzene rings [centroid–centroid distance = 3.779 (2) Å]

Functional nanofibrous biomaterials of tailored structures for drug delivery—a critical review

Nanofibrous biomaterials have huge potential for drug delivery, due to their structural features and functions that are similar to the native extracellular matrix (ECM). A wide range of natural and polymeric materials can be employed to produce nanofibrous biomaterials. This review introduces the major natural and synthetic biomaterials for production of nanofibers that are biocompatible and biodegradable. Different technologies and their corresponding advantages and disadvantages for manufacturing nanofibrous biomaterials for drug delivery were also reported. The morphologies and structures of nanofibers can be tailor-designed and processed by carefully selecting suitable biomaterials and fabrication methods, while the functionality of nanofibrous biomaterials can be improved by modifying the surface. The loading and releasing of drug molecules, which play a significant role in the effectiveness of drug delivery, are also surveyed. This review provides insight into the fabrication of functional polymeric nanofibers for drug delivery

Realization of Zero-Refractive-Index Lens with Ultralow Spherical Aberration

Optical complex materials offer unprecedented opportunity to engineer fundamental band dispersion which enables novel optoelectronic functionality and devices. Exploration of photonic Dirac cone at the center of momentum space has inspired an exceptional characteristic of zero-index, which is similar to zero effective mass in fermionic Dirac systems. Such all-dielectric zero-index photonic crystals provide an in-plane mechanism such that the energy of the propagating waves can be well confined along the chip direction. A straightforward example is to achieve the anomalous focusing effect without longitudinal spherical aberration, when the size of zero-index lens is large enough. Here, we designed and fabricated a prototype of zero-refractive-index lens by comprising large-area silicon nanopillar array with plane-concave profile. Near-zero refractive index was quantitatively measured near 1.55 um through anomalous focusing effect, predictable by effective medium theory. The zero-index lens was also demonstrated to perform ultralow longitudinal spherical aberration. Such IC compatible device provides a new route to integrate all-silicon zero-index materials into optical communication, sensing, and modulation, and to study fundamental physics on the emergent fields of topological photonics and valley photonics.Comment: 14 pages, 4 figure

Tetra­aqua­bis­[4-(1H-imidazol-1-yl-κN 3)benzoato]cobalt(II)

In the title compound, [Co(C10H7N2O2)2(H2O)4], the CoII atom lies on an inversion centre and displays a slightly distorted octa­hedral geometry. The coordination sphere is defined by two mutually trans N atoms from two 4-(imidazol-1-yl)benzoate ligands and the O atoms from four water mol­ecules. The crystal structure is stabilized by O—H⋯O hydrogen bonds