We report here a design method based on smart transformation optics (STO) to control the range of the permittivity values of the materials required to manufacture transformation optics devices. In particular, we show that it is possible to reduce the maximum electric permittivity value required to realize a STO device with certain functionality by means of a simple conceptual elastic stretching process. We illustrate the design procedure with two types of collimator meta-lens designs, which we call warping space collimator meta-lens and half fisheye collimator meta-lens, respectively. We provide design examples of these two types of lenses with the help of COMSOL Multiphysics software. These two design examples are fabricated with commonly available dielectric materials by means of 3D printing technology. For the functional verification of these two collimator lenses, we provide measurement results obtained with transverse electric waves of frequency range 7–13GHz.

The aim of this study was to develop an ultrasonic tooth-whitening apparatus using piezoelectric transducers,which enhance bleaching efficiency by applying ultrasound, while performing a teeth whitening procedure. For thispurpose, an ultrasonic transducer was designed and manufactured, and the effects of reduction in the whiteningmaterial’s concentration and in the whitening treatment time through using the ultrasound cavitation phenomenonwere confirmed. Also, the validity of this study was investigated by comparing the whitening performance with acommercialized optical whitener, through color comparison. The results revealed that the ultrasound whitenerproduced color values that were enhanced by as much as double that of the conventional LED light whiteningmethod. Even when the operational time was reduced by half, the ultrasound method showed superior performanceby over 54% compared to the conventional light whitener, revealing that the ultrasound method showed a remarkabletreatment reduction effect

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ABSTRACT:New dicyanovinyl end-capped reactive oligomers 2-5 containing flexible alkyl units were prepared from the condensation reaction of diamines with 1-(p-formylphenyl)-1-phenyl-2,2-dicyanoethene (1) by forming an azomethine linkage. Two arylate oligomers 7 and 8 containing azomethine bond were also prepared and compared with oligomers 2-5. All the oligomers were characterized by spectroscopies and elemental analysis. The reactive oligomers showed a good solubility in polar aprotic solvent such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMAcJ, and they were partially soluble in common organic solvents such as tetrahydrofuran (THF) and acetone. Their thermal properties including melting temperature, curability and thermal stabilities were examined. These oligomers undergo a curing reaction around 280-340°C. Upon heating the oligomers, thermally stable and insoluble network polymers were obtained. KEY WORDSEnd-Capped Reactive Oligomer I Thermal Stability / Enaryloxynitriles / Azomethine Group I Dicyanovinyl Group/ Introduction of reactive functional groups into oligomers, which undergo intramolecular cycloaddition or intermolecular crosslinking on heating, has important advantages over previously developed high molecular weight linear polymer system.

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