In situ doping control and electrical transport investigation of single and arrayed CdS nanopillars

Gu, Leilei,Liu, Xi,Kwon, Kyungmook,La, Chih-Chung,Lee, Min Hyung,Yu, Kyoungsik,Chueh, Yu-Lun,Fan, Zhiyong The Royal Society of Chemistry 2013 Nanoscale Vol.5 No.16

<P>Highly aligned intrinsic and indium doped CdS nanopillar arrays were fabricated via a template assisted Solid Source Chemical Vapor Deposition method (SSCVD). The prepared nanopillar arrays were well aligned, dense and uniform in diameter and length. Their geometry can be well defined by the design of the templates. These unique properties make them promising candidates for future photonic and optoelectronic devices. The structure of the prepared nanopillars has been studied by high resolution transmission electron microscopy and their different growth orientation as compared to those grown in free space has been observed and interpreted by the template induced change of the liquid-solid interfacial energy and the surface tension at the edge of the circular interface. To investigate electrical property of CdS nanopillars, vertical nanopillar array devices and horizontal individual nanopillar field-effect transistors have been fabricated and characterized. The measurements showed that the location of the indium doping source significantly affected carrier concentration, conductivity and field-effect mobility of the prepared CdS nanopillars. Particularly, it was found that conductivity could be improved by 4 orders of magnitude and field-effect mobility could be enhanced up to 50 cm(2) V(-1) s(-1) via proper doping control. These results enable further applications of CdS nanopillars in nano-optoelectronic applications such as photodetection and photovoltaics in the future.</P>

Predicting the flexural capacity of RC beam with partially unbonded steel reinforcement

Xiao-Hui Wang,Xi-La Liu 사단법인 한국계산역학회 2009 Computers and Concrete, An International Journal Vol.6 No.3

Due to the reduction of bond strength resulting from the high corrosion level of reinforcing bars, influence of this reduction on flexural capacity of reinforced concrete (RC) beam should be considered. An extreme case is considered, where bond strength is complete lost and/or the tensile steel are exposed due to heavy corrosion over a fraction of the beam length. A compatibility condition of deformations of the RC beam with partially unbonded length is proposed. Flexural capacity of this kind of RC beam is predicted by combining the proposed compatibility condition of deformations with equilibrium condition of forces. Comparison between the model’s predictions with the experimental results published in the literature shows the practicability of the proposed model. Finally, influence of some parameters on the flexural capacity of RC beam with partially unbonded length is discussed. It is concluded that the flexural capacity of the beam may not be influenced by the completely loss of bond of the whole beam span as long as the tensile steel can yield; whether or not the reduction of the flexural capacity of the beam resulting from the loss of bond over certain length may occur depends on the detailed parameters of the given beam.

Analysis of RC beam with unbonded or exposed tensile steel reinforcements and defective stirrup anchorages for shear strength

Xiao-Hui Wang,Xi-La Liu 사단법인 한국계산역학회 2012 Computers and Concrete, An International Journal Vol.10 No.1

Although the effect of corrosion of reinforcing bar on the shear behavior of the reinforced concrete (RC) beam had been simulated by tests of the beam with unbonded, half-exposed or wholeexposed tensile steel reinforcements as well as defective stirrup anchorages, theoretical methods to accurately predict remaining capacity of this kind of RC beams, especially shear capacity, are still lacking. Considering the possible position of the critical inclined crack, the actual pattern of strains in the concrete body within the partial length and the proposed compatibility condition of deformations of the RC beam, shear strength of the RC beam with unbonded or exposed tensile steel reinforcements and/or defective stirrup anchorages is predicted. Comparison between the model’s predictions with the experimental results published in the literature shows the practicability of the proposed model. Influence of the length of unbonded or exposed tensile steel reinforcements and the percentage of stirrups lacked end anchorages on the shear strength of the RC beam is discussed. It is concluded that, the shear strength of the RC beam with unbonded or exposed tensile steel reinforcements and/or defective stirrup anchorages is greatly influenced by the length of unbonded or exposed tensile steel reinforcements and the percentage of stirrups lacked end anchorages, this influence can be adverse, insignificant or even favourable, dependent on the given parameters of the corresponding normal bonded RC beam.

Influence of different fatigue loads and coating thicknesses on service performance of RC beam specimens with epoxy-coated reinforcement

Xiao-Hui Wang,Yang Gao,Run-Dong Gao,Jing Wang,Xi-La Liu 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3

Epoxy-coated reinforcing bars are widely used to protect the corrosion of the reinforcing bars in the RC elements under their in-service environments and external loads. In most field surveys, it was reported that the corrosion resistance of the epoxy-coated reinforcing bars is typically better than the uncoated bars. However, from the experimental tests conducted in the labs, it was reported that, under the same loads, the RC elements with epoxy-coated reinforcing bars had wider cracks than the elements reinforced with the ordinary bars. Although this conclusion may be true considering the bond reduction of the reinforcing bar due to the epoxy coating, the maximum service loads used in the experimental research may be a main reason. To answer these two phenomena, service performance of 15 RC beam specimens with uncoated and epoxy-coated reinforcements under different fatigue loads was experimentally studied. Influences of different coating thicknesses of the reinforcing bars, the fatigue load range and load upper limit as well as fatigue load cycles on the mechanical performance of RC test specimens are discussed. It is concluded that, for the test specimens subjected to the comparatively lower load range and load upper limit, adverse effect on the service performance of test specimens with thicker epoxy-coated reinforcing bars is negligible. With the increments of the coating thickness and the in-service loading level, i.e., fatigue load range, load upper limit and fatigue cycles, the adverse factor resulting from the thicker coating becomes noticeable.

An Aqueous Extract of Yunnan Baiyao Inhibits the Quorum-Sensing-Related Virulence of Pseudomonas aeruginosa

Zu-Guo Zhao,Shuang-Shuang Yan,Yun-Mei Yu,Na Mi,La-Xi Zhang,Jun Liu,Xiao-Ling Li,Fang Liu,Jun-Fa Xu,Wei-Qing Yang,Guo-Ming Li 한국미생물학회 2013 The journal of microbiology Vol.51 No.2

Yunnan Baiyao is a famous Chinese medicine that has long been directly applied to wounds to reduce bleeding, pain, and swelling without causing infection. However, little is known about its ability to prevent infection. The present study aimed to assess in vitro the anti-virulence activity of an aqueous extract of Yunnan Baiyao (YBX) using Pseudomonas aeruginosa as a pathogenic model. We found that a sub-MIC (2.5 mg/ml) of YBX can efficiently interfere with the quorum-sensing (QS) signaling circuit. Real-time polymerase chain reaction analysis showed that a sub-MIC of YBX downregulated the transcriptions of lasR, lasI, rhlR, and rhlI,which resulted in global attenuation of QS-regulated virulence activities, such as biofilm formation, and secretion of LasA protease, LasB elastase and pyocyanin. Further, YBX reduced the motility of P. aeruginosa related to QS, and impaired the formation of biofilms. These results suggest that YBX may possess global inhibitory activity against the virulence of P. aeruginosa and that YBX may also exhibit antimicrobial activity in vivo. The present study suggests that Yunnan Baiyao represents a potential source for isolating novel, safe, and efficacious antimicrobial agents.