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Foroutan, Farzad,Jokerst, Jesse V.,Gambhir, Sanjiv S.,Vermesh, Ophir,Kim, Hae-Won,Knowles, Jonathan C. American Chemical Society 2015 ACS NANO Vol.9 No.2
<P>Ultrasound imaging is a powerful tool in medicine because of the millisecond temporal resolution and submillimeter spatial resolution of acoustic imaging. However, the current generation of acoustic contrast agents is primarily limited to vascular targets due to their large size. Nanosize particles have the potential to be used as a contrast agent for ultrasound molecular imaging. Silica-based nanoparticles have shown promise here; however, their slow degradation rate may limit their applications as a contrast agent. Phosphate-based glasses are an attractive alternative with controllable degradation rate and easily metabolized degradation components in the body. In this study, biodegradable P2O5-CaO-Na2O phosphate-based glass nanospheres (PGNs) were synthesized and characterized as contrast agents for ultrasound imaging. The structure of the PGNs was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance P-31 MAS NMR), and Fourier transform infrared (FTIR) spectroscopy. The SEM images indicated a spherical shape with a diameter size range of 200-500 nm. The XRD, P-31 NMR, and FTIR results revealed the amorphous and glassy nature of PGNs that consisted of mainly Q(1) and Q(2) phosphate units. We used this contrast to label mesenchymal stem cells and determined in vitro and in vivo detection limits of 5 and 9 mu g/mL, respectively. Cell counts down to 4000 could be measured with ultrasound imaging with no cytoxicity at doses needed for imaging. Importantly, ion-release studies confirmed these PGNs biodegrade into aqueous media with degradation products that can be easily metabolized in the body.</P>
A TWA Optical Receiver with Hybrid Integrated InP Detector
Hyeon Cheol Ki,Carl S.P. Chun,Joy Laskar,Nan Marie Jokerst,Martin A.Brooke,Yong-Sun Yoon,Jin Yeong Kang,Dong Sung Ma 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.6
To investigate the usefulness and feasibility of the TWA structure for low cost wide band system applications we designed a TWA optical receiver using low cost commercial process. The measured results show it is possible to achieve 18 ㎓ bandwidth with 7㏈ gain using low cost GaAs MESFET process with 20 ㎓ cut-off frequency. We also try, for the first time, the operation of an hybrid integrated OEIC using a fabricated TWA optical receiver and a thin film photo-detector 50㎛ in diameter. These results demonstrate that it is feasible to applicate TWA for the low cost wide band systems and to hybrid integrate wide band MMIC with thin film detectors for inexpensive high speed OEICs.
Driscoll, T.,Kim, H.-T.,Chae, B.-G.,Kim, B.-J.,Lee, Y.-W.,Jokerst, N. M.,Palit, S.,Smith, D. R.,Di Ventra, M.,Basov, D. N. American Association for the Advancement of Scienc 2009 Science Vol.325 No.5947
<P>The resonant elements that grant metamaterials their distinct properties have the fundamental limitation of restricting their useable frequency bandwidth. The development of frequency-agile metamaterials has helped to alleviate these bandwidth restrictions by allowing real-time tuning of the metamaterial frequency response. We demonstrate electrically controlled persistent frequency tuning of a metamaterial, which allows the lasting modification of its response by using a transient stimulus. This work demonstrates a form of memory capacitance that interfaces metamaterials with a class of devices known collectively as memory devices.</P>