Frequency Tunable Phononic Crystal Flat Lens for Subwavelength Imaging

In this paper, we present a thickness-contrast based flat lens for subwavelenth imaging in an aluminum plate. The lens is made of phononic crystal (PC) with a triangular lattice arrangement of through holes drilled over an aluminum plate. Subwave-length imaging is achieved by exploiting the concept of negative refraction of A0 plate mode for the optical dispersion branch of the PC. The wavenumbers are matched at a design frequency by creating a step change in the thickness of the PC-lens and host plate. The thickness-contrast results in refractive index of minus one at the interface of the lens and host plate. Negative refraction-based lens overcomes the diffraction limit and enables focusing of flexural waves in an area less than a square wavelength. We validate the flat lens design at a single design frequency through numerical simulations and experiments. Further, we numerically demonstrate the tunability of the lens design over a broadband frequency range by modifying the thickness-contrast between the lens and host plate. The proposed frequency tunable design is promising for many applications such as ultrasonic inspection, tetherless energy transfer, and energy harvesting, where the localization of wave energy in a small spot is desirable.

CO-CRYSTALS OF ACTIVE PHARMACEUTICAL INGREDIENT-IBUPROFEN LYSINE

Objective: Co-crystal is defined as a crystalline complex of two or more neutral molecules bound together primarily by hydrogen bonding or other non-covalent interactions. The pharmaceutical co-crystal involves crystal lattice arrangement between an Active Pharmaceutical Ingredient (API) with another pharmaceutically acceptable molecule. Co-crystals of API are preferred since they depict improved solubility, dissolution, stability, compressibility in comparison with API. Ibuprofen lysine (IL), frequently used analgesic and the anti-inflammatory drug has poor aqueous solubility and compressibility. This work shows the feasibility and optimal conditions for the preparation of co-crystals of ibuprofen lysine using Polyvivylpyrrolidone K25 (PK 25) and Polyvivylpyrrolidone K30 (PK 30) as co-formers. Methods: In this study, we prepared and studied the solubility, drug content, flow properties, physical stability of novel co-crystal, consisting of IL and PK 25/PK 30. The co-crystal IL: PK 30 (at a molar ratio of 0.29:0.5) and IL: PK 25 (at a molar ratio of 0.58:1) were characterized by X-ray analysis, infrared spectroscopy and thermal analysis. Furthermore, the tablet formulations of the co-crystals were subjected to in vitro dissolution and in vivo analgesic activity, with the goal of comparing the co-crystals with IL and the marketed tablet of ibuprofen (Brufen®) respectively. Results: The IL: PK co-crystals demonstrated superior solubility and the dissolution properties over IL. The compression properties of the co-crystals were similar to IL. The co-crystals exhibited higher analgesic activity than the marketed tablet. Conclusion: The results indicated the use of PK 25 and PK 30 as safe and promising co-crystal formers.

Linear chains of nanomagnets: engineering the effective magnetic anisotropy

Tunable effective magnetic anisotropy is achieved by engineering the thickness and lattice arrangement of linear chains of nanomagnets.

Lattice arrangement of myosin filaments correlates with fiber type in rat skeletal muscle

The thick (myosin-containing) filaments of vertebrate skeletal muscle are arranged in a hexagonal lattice, interleaved with an array of thin (actin-containing) filaments with which they interact to produce contraction. X-ray diffraction and EM have shown that there are two types of thick filament lattice. In the simple lattice, all filaments have the same orientation about their long axis, while in the superlattice, nearest neighbors have rotations differing by 0° or 60°. Tetrapods (amphibians, reptiles, birds, and mammals) typically have only a superlattice, while the simple lattice is confined to fish. We have performed x-ray diffraction and electron microscopy of the soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat and found that while the EDL has a superlattice as expected, the SOL has a simple lattice. The EDL and SOL of the rat are unusual in being essentially pure fast and slow muscles, respectively. The mixed fiber content of most tetrapod muscles and/or lattice disorder may explain why the simple lattice has not been apparent in these vertebrates before. This is supported by only weak simple lattice diffraction in the x-ray pattern of mouse SOL, which has a greater mix of fiber types than rat SOL. We conclude that the simple lattice might be common in tetrapods. The correlation between fiber type and filament lattice arrangement suggests that the lattice arrangement may contribute to the functional properties of a muscle.

Lattice arrangement of myosin filaments correlates with fiber type in rat skeletal muscle

The thick (myosin-containing) filaments of vertebrate skeletal muscle are arranged in a hexagonal lattice, interleaved with an array of thin (actin-containing) filaments with which they interact to produce contraction. X-ray diffraction and electron microscopy have shown that there are two types of thick filament lattice. In the simple lattice, all filaments have the same orientation about their long axis, while in the super lattice, nearest neighbors have rotations differing by 60°. Tetrapods (amphibians, reptiles, birds, mammals) typically have only a super lattice, while the simple lattice is confined to fish. We have carried out X-ray diffraction and electron microscopy of the soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat and found that while the EDL has a super-lattice, as expected, the SOL has a simple lattice. The EDL and SOL of the rat are unusual in being essentially pure fast and slow muscles respectively. The mixed fiber content of most tetrapod muscles and/or lattice disorder may explain why the simple lattice has not been apparent in these vertebrates before. This is supported by only weak simple lattice diffraction in the X-ray pattern of mouse SOL, which has a greater mix of fiber types than rat. We conclude that the simple lattice might be common in tetrapods. The correlation between fiber type and filament lattice arrangement suggests that the lattice arrangement may contribute to the functional properties of a muscle.SummaryThe three-dimensional arrangement of thick filaments in skeletal muscle is studied by X-ray diffraction and electron microscopy. A correlation is found between thick filament lattice type (simple or super lattice) and fiber type (fast/slow). This suggests that lattice organization contributes to muscle functional properties

Tensile and Interfacial Loading Characteristics of Boron Nitride-Carbon Nanosheet Reinforced Polymer Nanocomposites

The discovery of hybrid boron nitride–carbon (BN–C) nanostructures has triggered enormous research interest in the design and fabrication of new generation nanocomposites. The robust design of these nanocomposites for target applications requires their mechanical strength to be characterized with a wide range of factors. This article presents a comprehensive study, with the aid of molecular dynamics analysis, of the tensile loading mechanics of BN–C nanosheet reinforced polyethylene (PE) nanocomposites. It is observed that the geometry and lattice arrangement of the BN–C nanosheet influences the tensile loading characteristics of the nanocomposites. Furthermore, defects in the nanosheet can severely impact the tensile loading resistance, the extent of which is determined by the defect’s location. This study also found that the tensile loading resistance of nanocomposites tends to weaken at elevated temperatures. The interfacial mechanics of the BN–C nanocomposites are also investigated. This analysis revealed a strong dependency with the carbon concentration in the BN–C nanosheet.

Ultra Thin Flexible Octagonal Metamaterials Absorber

<span lang="IN">An ultra thin flexible octagonal metamaterial absorber on 0.13 mm fastFilm D27 material has been presented in this paper. CST microwave studio was used in designing and simulating the octagonal metamaterial absorber. The flexible octagonal metamaterial absorber was resonated at 10 GHz with highly perfect absorbance of 99.98%. However, Full Width Half Maximum (FWHM) of the absorbance was relatively small 135 MHz affected from the ultra thin substrate used. By using triangular lattice arrangement of the unit cell, the FWHM could be increased to 171 MHz. Besides that, combination of resonating frequencies technique also had increased the FWHM more than 74% increment from basic unit cell with one resonance frequency. The flexibleness of the metamaterial absorber could increase the functionality of the metamaterial absorber to be used in any application especially in reducing radar cross section for stealth application.</span>