Browsing by Author "Chen, Yi-Yang"

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Evidence of DNA transfer through F-pilus channels during Escherichia coli conjugation
(2008-07-01)
Shu, An-Chi
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Wu, Chien-Chen
;
Chen, Yi-Yang
;
Peng, Hwei-Ling
;
Chang, Hwan-You
The mechanism of DNA transfer from Escherichia coli (E. coli) Hfr donor strain AT2453 to recipient strain AB1157 during the conjugation process has been investigated by liquid atomic force microscopy (AFM). With the success of immobilizing both E. coli strains on gelatin-treated glass under aqueous solution, the F-pilus between an E. coli mating pair could be clearly imaged and dissected by an AFM probe. Another AFM probe functionalized with an anti-single-stranded DNA (ssDNA) antibody was then applied to detect transferring ssDNA. According to the AFM force spectrum, the transferring ssDNA could be detected only in the dissected area with a binding force of 109 5 pN measured. Our results provide direct evidence indicating that the DNA was transferred through the F-pilus channel between an E. coli mating pair during their conjugation.
Improved Rear-Side Passivation by Atomic Layer Deposition Al2O3/SiNx Stack Layers for High V-OC Industrial p-Type Silicon Solar Cells
(2013-09-01)
Lin, Je-Wei
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Chen, Yi-Yang
;
Gan, Jon-Yiew
;
Hseih, Wei-Ping
;
Du, Chen-Hsu
This research develops high open-circuit voltage (V-OC) p-type industrial screen-printed silicon solar cells using improved rear surface passivation. It shows a significant improvement in the minority carrier lifetime by low temperature (<450 degrees C) thermal atomic layer deposition of Al2O3 layers and plasma-enhanced chemical vapor deposition of SiNx passivation layers. An increase in the V-OC and the short-circuit current (J(SC)) due to an improved long-wavelength response are also demonstrated. With the optimized stack layers, a high efficiency of 19.2% across a large area (156 cm(2)) is seen. Furthermore, the rear-side passivation scheme can be easily integrated into the conventional screen-printed process. This is very promising for in-line solar cell manufacturing.
Large scale two-dimensional nanobowl array high efficiency polymer solar cell
(2012)
Chen, Szu-Ying
;
Yen, Yu-Ting
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Chen, Yi-Yang
;
Hsu, Chain-Shu
;
Chueh, Yu-Lun
A two-dimensional nanobowl array (2D-NBRs) with a unique honeycomb nanostructure was demonstrated with controllable morphologies synthesized by the Langmuir-Blodgett (LB) method. The periodicity of 2D-NBRs can be controlled by utilizing different diameters of polystyrene (PS) balls ranged from 500 nm, 870 mu m, 1 mu m to 2 mu m. The reflectance measurements revealed that the planar structure with a poly(3-hexylthiophene) (P3HT)/(6,6)-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction layer as an active layer exhibits a reflectance of similar to 20 %, while a significant reduction of the reflectance <5-7 % can be achieved after formation of 2D-NBRs at a PS ball diameter of 500 nm, which perfectly matches simulation results. From experimental results, the highest efficiency of 5.4 % with a filling factor of 66 % was achieved for the device with 2D-NBRs at PS ball diameter of 870 nm. Compared to a planar device with an efficiency of 3.9 %, a maximum enhancement of similar to 40 % can be achieved owing to the enhancement of Jsc because of unique honeycomb geometry, which exhibits a broadband and omnidirectional light harvesting behavior. Furthermore, a flexible solar cell was demonstrated with an enhanced efficiency of 30 % for a planar structure of 1 % to 1.3 % for 2D-NBRs structure.
Surface Rigidity Change of Escherichia coli after Filamentous Bacteriophage Infection
(2009-04-21)
Chen, Yi-Yang
;
Wu, Chien-Chen
;
Hsu, Jye-Lin
;
Peng, Hwei-Ling
;
Chang, Hwan-You
In this study, the feasibility using atomic force microscopy (AFM) to study the interaction between bacteriophages (phages) and bacteria in situ was demonstrated here. Filamentous phage M 13 specifically infects the male Escherichia coli, which expresses F-pili. After infection, E. coli become fragile and grows at a slower rate. AFM provides a powerful tool for investigating these changes in a near-physiological environment. Using high-resolution AFM in phosphate-buffered saline, the damage to the lipopolysaccharide (LPS) layer on the outer membrane of the M13 phage-infected E. coli was observed. The membrane became smoother and more featureless compared to those that were not infected. Besides, the force-distance (f-d) curves were measured to reveal the surface rigidity change in E. coli after M13 phage infection. The effective spring constant and Young's modulus of E. coli decreased after M13 phage infection. Furthermore, the AFM tip was pressed against E. coli to stud), the response of E. coli under load before and after M 13 phage infection. The results showed that after infection E. coli became less rigid and the membrane was also damaged. However, the stiffness changes, including the spring constant and Young's modulus of E. coli, are negligible after M 13 phage infection compared with those in previous reports, which may be one of the reasons that E. coli still can maintain its viability after filamentous phage infection.