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Dynamic Microcontainers as Microvacuums for Collecting Nanomaterials After Clinical Treatments
Choi, Daniel S.,Park, Jungrae,Ke Xu,Kringel, Rose,Choi, John J.,Jeon, In Tak,Young Keun Kim IEEE 2013 IEEE transactions on magnetics Vol.49 No.7
<P>We present a feasible method to collect ferromagnetic nanomaterials(FNMs) after clinical utilization by employing ferromagnetic microcontainers (MCs). The cubic MCs with dimensions of 200 micrometers have gold-coated nickel frames and were tethered such a way that they are able to remove FNMs from cells with the use of an external magnetic field. The study has been conducted in two parts: 1) enhancement of the motion of MCs in glass-based microfluidic channels filled with viscous fluids by magnetically-driven spinning MCs, i.e., “dynamic MCs”; 2)sweeping FNMs from the cells using magnetic attractive forces between FNMs and MCs through a “microvacuum”process. Our study shows that spinning MCs can transport better than nonspinning MCs through viscous fluids. We found that approximately 70% of FNMs internalized with human embryonic cells (HEK-293) were removed from the cells by the spinning MCs. Such in-vitro experiments suggest the possibility of resolving the issue of removing FNMs used for clinical treatments from human body after treatments.</P>
Kim, Y.S.,Choi, J.H.,Bae, H.J.,Nilsson, T.,Daniel, G. 한국문화재보존과학회 1992 보존과학회지 Vol.1 No.1
Micromorphological changes in waterlogged archaeological woods excavated from Sweden and Germany were investigated. Especially bacterial attacks on those wood samples under near anaerobic conditions were examined by transmission electron microscopy(TEM). The major feature of micromorphological alterations in those wood samples was the preferential destruction of secondary wood cell wall. In contrast, the middle lamella was not extensively degraded. Three distinct degradation patterns by bacteria were observed : erosion, cavitation and tunnelling bacteria. Erosion and cavitation bacteria attacked primarily $S_2$ layer, whereas tunnelling bacteria made the tunnel-like degradation along the $S_1$ layer. Tunnelling bacteria, in some samples, were able to degrade tunnel in the lignin-rich areas, such as middle lamella, suggesting that these bacteria had the capacity to degrade the lignin. IR spectra indicate that hemicellulose and cellulose in the waterlogged woods were preferentially decomposed. Breakdown of the lignin, on the other hand, was much slower.
Choi, Wonjae,Shi, Fan,Lowe, Michael J.S.,Skelton, Elizabeth A.,Craster, Richard V.,Daniels, William L. Elsevier 2018 NDT & E international Vol.98 No.-
<P><B>Abstract</B></P> <P>The scattering of waves by rough surfaces plays a significant role in many fields of physical sciences including ultrasonics where failure surfaces are often rough and their accurate identification is critical. The prediction of the strength of scattering can be hampered when the roughness is not adequately characterised and this is a particular issue when the surface roughness is within an order of the incident wavelength. Here we develop a methodology to reconstruct, and accurately represent, rough surfaces using an AutoRegressive (AR) process that then allows for rapid numerical simulations of ultrasonic wave rough surface scattering in three dimensions. Gaussian, exponential and AR surfaces are reconstructed based on real surface data and the statistics of the surfaces are compared with each other. The statistics from the AR surfaces agree well with those from actual rough surfaces, taken from experimental samples, in terms of the heights as well as the gradients, which are the two main factors in accurately predicting the wave scattering intensities. Ultrasonic rough surface scattering is simulated numerically using the Kirchhoff approximation, and comparisons with Gaussian, exponential, AR and real sample surfaces are performed; scattering intensities found using AR surfaces show the best agreement with the real sample surfaces.</P>
Overcoming the Diffraction Limit Using Multiple Light Scattering in a Highly Disordered Medium
Choi, Youngwoon,Yang, Taeseok Daniel,Fang-Yen, Christopher,Kang, Pilsung,Lee, Kyoung Jin,Dasari, Ramachandra R.,Feld, Michael S.,Choi, Wonshik American Physical Society 2011 Physical review letters Vol.107 No.2
High-quality hyperspectral reconstruction using a spectral prior
Choi, Inchang,Jeon, Daniel S.,Nam, Giljoo,Gutierrez, Diego,Kim, Min H. Association for Computing Machinery 2017 ACM transactions on graphics Vol. No.
<P>We present a novel hyperspectral image reconstruction algorithm, which overcomes the long-standing tradeoff between spectral accuracy and spatial resolution in existing compressive imaging approaches. Our method consists of two steps: First, we learn nonlinear spectral representations from realworld hyperspectral datasets; for this, we build a convolutional autoencoder, which allows reconstructing its own input through its encoder and decoder networks. Second, we introduce a novel optimization method, which jointly regularizes the fidelity of the learned nonlinear spectral representations and the sparsity of gradients in the spatial domain, by means of our new fidelity prior. Our technique can be applied to any existing compressive imaging architecture, and has been thoroughly tested both in simulation, and by building a prototype hyperspectral imaging system. It outperforms the state-of-the-art methods from each architecture, both in terms of spectral accuracy and spatial resolution, while its computational complexity is reduced by two orders of magnitude with respect to sparse coding techniques. Moreover, we present two additional applications of our method: hyperspectral interpolation and demosaicing. Last, we have created a new high-resolution hyperspectral dataset containing sharper images of more spectral variety than existing ones, available through our project website.</P>
Thoma, Daniel S.,Yoon, So-Ra,Cha, Jae-Kook,Lim, Hyun-Chang,Lee, Jung-Seok,Choi, Seong-Ho,Jung, Ui-Won Springer-Verlag 2018 Clinical oral investigations Vol.22 No.2
<P>The use of rhBMP-2-coated implants in a graft-free SFE might show an advantage in early implant stability to prevent collapse of membrane. However, a potential clinical benefit still needs to be proven.</P>
Mariam S. Mansouri,안부현,Hamda Al Shibli,Hamad Al Yassi,Tawaddod Saif Alkindi,이지성,김영근,류종은,Daniel S. Choi 한국물리학회 2018 Current Applied Physics Vol.18 No.11
We present a novel process to fabricate three-dimensional (3D) metallic patterns from 3D printed polymeric structures utilizing different hygroscopic swelling behavior of two different polymeric materials. 3D patterns are printed with two different polymers as cube shape. The surface of the 3D printed polymeric structures is plated with nickel by an electroless plating method. The nickel patterns on the surface of the 3D printed cube shape structure are formed by removing sacrificial layers using the difference in the rate of hygroscopic swelling between two printing polymer materials. The hygroscopic behavior on the interfaced structure was modeled with COMSOL Multiphysics. The surface and electrical properties of the fabricated three-dimensional patterns were analyzed and characterized.
Stein, Gary S.,Zaidi, Sayyed K.,Stein, Janet L.,Lian, Jane B.,Van Wijnen, Andre J.,Montecino, Martin,Young, Daniel W.,Javed, Amjad,Pratap, Jitesh,Choi, Je-Yong,Ali, Syed A.,Pande, Sandhya,Hassan, Moha Wiley (Blackwell Publishing) 2009 Annals of the New York Academy of Sciences Vol.1155 No.1
<P>There is growing awareness that the fidelity of gene expression necessitates coordination of transcription factor metabolism and organization of genes and regulatory proteins within the three-dimensional context of nuclear architecture. The regulatory machinery that governs genetic and epigenetic control of gene expression is compartmentalized in nuclear microenvironments. Temporal and spatial parameters of regulatory complex organization and assembly are functionally linked to biological control and are compromised with the onset and progression of tumorigenesis. High throughput imaging of cells, tissues, and tumors, including live cell analysis, is expanding research's capabilities toward translating components of nuclear organization into novel strategies for cancer diagnosis and therapy.</P>
Stein, Gary S.,Zaidi, Sayyed K.,Stein, Janet L.,Lian, Jane B.,van Wijnen, Andre J.,Montecino, Martin,Young, Daniel W.,Javed, Amjad,Pratap, Jitesh,Choi, Je-Yong,Ali, Syed A.,Pande, Sandhya,Hassan, Moha Canadian Science Publishing 2009 Biochemistry and cell biology Vol.87 No.1
<P> Epigenetic control is required to maintain competency for the activation and suppression of genes during cell division. The association between regulatory proteins and target gene loci during mitosis is a parameter of the epigenetic control that sustains the transcriptional regulatory machinery that perpetuates gene-expression signatures in progeny cells. The mitotic retention of phenotypic regulatory factors with cell cycle, cell fate, and tissue-specific genes supports the coordinated control that governs the proliferation and differentiation of cell fate and lineage commitment. </P>