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Optical Characterization of ZnMnO Thin Films on c-Al2O3
H. J. LIN,D. Y. Lin,J. S. Wu,W. C. CHOU,C. S. YANG,J. S. WANG,W. H. Lo 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1
Various optical measurement technologies have ben used to characterize ZnMnO thin filmswith different Mn compositions grown by molecular beam epitaxy(MBE) on c-Al2O3 substrates. Thelat- tice constant and the crystalization quality have ben evaluated by using X-ray diraction (XRD). Photoluminescence (PL) has ben used to reveal the neutral-donor-bound exciton (D0X) and to checkthelm'squality. Defect-relatedabsorptionsignatures,inadditiontonear-band-edgeabsorp- tion, due to the zinc vacancy and the donor-aceptor pair (DAP) have ben found in the surface photovoltagespectra(SPS).Freexcitonictransitionsandtheirphonon-asistedreplicashaveben observed in the re ectance spectra. Our experimental results not only unveil specic optical tran- sitionenergies but also indicate arapid materiald deterioration whenMn incorporation goes beyond a certain amount to cause manganese segregation. Various optical measurement technologies have ben used to characterize ZnMnO thin filmswith different Mn compositions grown by molecular beam epitaxy(MBE) on c-Al2O3 substrates. Thelat- tice constant and the crystalization quality have ben evaluated by using X-ray diraction (XRD). Photoluminescence (PL) has ben used to reveal the neutral-donor-bound exciton (D0X) and to checkthelm'squality. Defect-relatedabsorptionsignatures,inadditiontonear-band-edgeabsorp- tion, due to the zinc vacancy and the donor-aceptor pair (DAP) have ben found in the surface photovoltagespectra(SPS).Freexcitonictransitionsandtheirphonon-asistedreplicashaveben observed in the re ectance spectra. Our experimental results not only unveil specic optical tran- sitionenergies but also indicate arapid materiald deterioration whenMn incorporation goes beyond a certain amount to cause manganese segregation.
Yihui Wang,Joseph P. Hoffmann,Chau-Wen Chou,Kerstin Höner zu Bentrup,Joseph A. Fuselier,Jacob P. Bitoun,William C. Wimley,Lisa A. Morici 한국미생물학회 2020 The journal of microbiology Vol.58 No.7
Gram-negative bacteria secrete outer membrane vesicles (OMVs) that play critical roles in intraspecies, interspecies, and bacteria-environment interactions. Some OMVs, such as those produced by Pseudomonas aeruginosa, have previously been shown to possess antimicrobial activity against competitor species. In the current study, we demonstrate that OMVs from Burkholderia thailandensis inhibit the growth of drug-sensitive and drug-resistant bacteria and fungi. We show that a number of antimicrobial compounds, including peptidoglycan hydrolases, 4-hydroxy-3-methyl-2-(2-nonenyl)- quinoline (HMNQ) and long-chain rhamnolipid are present in or tightly associate with B. thailandensis OMVs. Furthermore, we demonstrate that HMNQ and rhamnolipid possess antimicrobial and antibiofilm properties against methicillin- resistant Staphylococcus aureus (MRSA). These findings indicate that B. thailandensis secretes antimicrobial OMVs that may impart a survival advantage by eliminating competition. In addition, bacterial OMVs may represent an untapped resource of novel therapeutics effective against biofilm- forming and multidrug-resistant organisms.
C.T. Hsieh,M.W. Lin,C.L. Chang,Y.C. Ho,S.Y. Chen,J. Wang,M.C. Chou,J.Y. Lin,C.H. Pai,P.H. Lin,L.C. Tai,S.H. Chen,G.Y. Tsaur,C.C. Kuo,T.Y. Chien 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
A general method for fabricating transient plasma structures with high-intensity laser pulses is developed to gain fine control over laser-plasma interactions. These structures have been used as programmable photonic devices in the development of laser-wakefield accelerators, soft X-ray lasers and plasma nonlinear optics driven by multi-terawatt laser pulses. Plasma ramps are used to control electron injection in laser-wakefield accelerators, plasma waveguides are used to enhance the efficiency of soft X-ray lasers by orders of magnitude and periodic plasma structures are used to achieve quasi-phase matching in relativistic harmonic generation. By scanning the interaction length with the same plasma-fabrication method, tomographic measurements are carried out to resolve the injection/acceleration process in laser-wakefield accelerators and amplification processes in X-ray lasers and relativistic harmonic generation. A theoretical analysis and a computer simulation are also carried out to provide insightful pictures of these processes. These research works show that by controlling plasma structures with optical fabrication methods, laser-plasma interaction can be engineered to expand and enrich the frontier of high-field physics.
Cytoskeletal Patterns, In Vitro Maturation and Parthenogenetic Development of Rabbit GV Oocytes
Ju, J.C.,Chen, T.H.,Tseng, J.K.,Tsay, C.,Yeh, S.P.,Chou, P.C.,Chen, C.H.,Liu, C.T. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.12
The purposes of this study were to optimize the in vitro maturation (IVM) and culture (IVC) systems of rabbit oocytes. Cytoskeletal structures in the germinal vesicle stage (GV) and during IVM are also investigated. Ovaries were transported from local slaughterhouses and the cumulus-oocyte complexes (COCs) were collected from ovarian follicles (${\geq}1mm$). COCs were randomly allocated to TCM199-based medium ($T_1$, TCM-199) supplemented with $NaHCO_3$, glucose, sodium pyruvate and FSH ($T_2$), $T_2+E_2+LH$ ($T_3$), $T_3+FBS$ ($T_4$), or $T_1+E_2+LH+FSH+FBS$ ($T_5$), for IVM. In Experiment 1, COCs were retrieved from the follicles and 51 GV oocytes were fixed in the fixative (MTSB-XF) for nuclear and cytoplasmic examinations. In Experiment 2, progressive changes of both the nucleus and the cytoskeleton were examined at 0, 6, 16, and 20 h after IVM. Maturation (MR) and developmental rates were assessed in Experiment 3. Cytoplasmic microtubules (MT) were clearly observed in rabbit GV oocytes. To our knowledge, this is the first report that describes the appearance of MT structures in the GV stage ooplasm. Tremendous variations in cytoskeletal alterations were observed among treatments with the exception of the vitelline ring (VR), which is constantly visible and unchanged during maturation. Germinal vesicle breakdown (GVBD) does not occur at 6 h after onset of maturation culture. When the oocytes for IVM were collected within 2 h, results from Experiment 3 showed that rates of nuclear maturation were 42, 8, 42, 37 and 65% at 16 h of IVM for $T_1$ through $T_5$, respectively, in which $T_1$, $T_4$ and $T_5$ had significantly greater MR than those in other groups (p<0.05). Morula/blastocyst development after parthenogenetic activation ranged from 20 to 63% with significantly greater rates in $T_3$, $T_4$ and $T_5$ (p<0.05). These results suggested that oocytes recovered from slaughterhouse ovaries can be matured and parthenogenetically activated in vitro, but the MR remained low in this study. Addition of $E_2$ and LH in the medium may be beneficial for cytoplasmic maturation, but FBS exerts a nega- tive role in the subsequent development of parthenogenetic embryos when energy substrates are provided in the IVC media. More studies are required for improving the MR and further development of the GV stage rabbit oocytes.
Synchronized Bursting Induced by Network Connectivity in Cortical Neuronal Cultures
L.C. Jia,P.-Y. Lai,C. K. Chan,C.H. Chang,C.R. Han,M.T. Tsai,Y.S. Chou 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I
Synchronization of cortical neural cultures is studied as a function of the effective network connectivity in the phenomenon of synchronized firing (SF). The synchronized bursting frequency (during SF) of the network is found to be much slower than the characteristic time scale of a neuron and increases with the network connectivity. Using fluorescence imaging techniques, we found that SF occurs only when the incubation time is longer than some critical age tc and the synchronized bursting frequency f increases with time as f = fc + fo log( t tc ). Furthermore, tc is found to scale with the cell plating density as tc 1 p . Based on the result of photolysis of neurons, the synchronized bursting frequency is shown to be related to the network connectivity, hence, the growth behavior can be inferred from the measured SF frequencies. We further build a network growth model with the characteristics of an early stage active growth followed by a late-stage retarded growth, which can account for the experimental data quantitatively. Electrophysiological measurements using double-patch techniques reveal that even though the bursting frequencies are synchronized, the intra-burst spikes are not. We also present a mean-field model of the neural network that enables the neuron firing to be inhibited and generates inter-spike intervals with long time scales resulting in bursting.
Z축 운전구조를 갖는 선형 영구자석형 동기 전동기 운전제어에 관한 연구
이진하(C.H. Lee),최철(C.Chou),박한용(H.W. Park),김철우(C.U. Kim) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(2)
In this study a control system with variable gain schedule using real speed and moving direction is proposed to control a Permanent Magnet Linear Synchronous Motor (PMLSM) with Z-axis operation structure. <br/> The implementation of the controller is designed on the DSP TMS32OC32 board PMLSM is operated by using 4-point absolute positions profile with each velocity, acceleration and deceleration. The direction of the initial angle action for starting is set from the lower limit point to the upper limit point on PMLSM operation stroke The effectiveness of a control system with variable gam schedule is demonstrated by some experimental results<br/>