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ABSTRACT: This paper introduced a wafer-scale fabrication approach for the preparation of nanochannels with high-aspect ratio (the ratio of the channel depth to its width). Edge lithography was used to pattern nanogaps in an aluminum film, which was functioned as deep reactive ion etching mask thereafter to form the nanochannel. Nanochannels with aspect ratio up to 172 and width down to 44 nm were successfully fabricated on a 4-inch Si wafer with width nonuniformity less than 13.6%. A microfluidic chip integrated with nanometer-sized filters was successfully fabricated by utilizing the present method for geometric-controllable nanoparticle packing.
Biomicrofluidics 03/2012; 6(1):16502-165028. · 3.37 Impact Factor
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Peng Guo,
Ying-jiang Ye,
Ke-wei Jiang,
Zhi-dong Gao,
Tie Wang,
Mu-jun Yin,
You-li Wang,
Qi-wei Xie,
Xiao-dong Yang,
Jun Qu,
Bin Liang,
Kai Shen, Fei Xie,
Hou-pu Yang,
Shan Wang
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ABSTRACT: To evaluate the learning curve of complete mesocolic excision(CME) for colon cancer.
Clinical data of 75 cases in whom CME was performed by a group of surgeons in the Department of Gastrointestinal Surgery, Peking University People's Hospital from November 2009 to June 2011 were reviewed. The patients were divided into three groups(groups A, B, C, 25 cases in each group) by operative chronologic sequence.
There were no significant differences in age, sex, preoperative staging, cancer location, operation history of abdomen, ASA among the three groups(P>0.05). The operative time in group A was (205.4 ± 53.2) min and decreased to (180.4 ± 29.7) min in group B and (169.8 ± 41.3) min in group C (P<0.05). The postoperative hospital stay decreased from (17.8 ± 10.9) d in group A to(12.9 ± 4.1) d in group B and(11.0 ± 3.5) d in group C(P<0.05). The postoperative complication rate decreased from 32%(8/25) in group A and 36%(9/25) to 8%(2/25) in group C. The specimen quality was superior in group C compared to group A (WEST grade C above were 20 and 11 respectively, P<0.05). There were no significant differences in intraoperative bleeding, time to first flatus, postoperative fasting time, number of retrieved lymph nodes among the three groups(P>0.05).
From the learning curve of CME, surgeons can learn CME skill after performing 25 cases.
Zhonghua wei chang wai ke za zhi = Chinese journal of gastrointestinal surgery 01/2012; 15(1):28-31.
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ABSTRACT: Connector fretting propensity is generally evaluated through an exhaustive series of experimental tests, making the connector design and validation process time consuming and costly. Thus, a method using modeling and simulation techniques to predict the influence of various design factors on vibration-induced fretting propensity in electrical connectors method would very beneficial to those responsible for connector design and application. One approach is to use detailed finite element models for the connector system to relate the actual dynamics of the contact interface to the threshold vibration levels required for the onset of fretting and the relative motion transfer function. The present study describes one such model for a single tin-plated blade/receptacle connector pair. Concurrent simulation and experimental studies were performed to evaluate the threshold vibration levels as a function of excitation frequency, interface friction coefficient, and normal force. Good correlation between the experimentally observed results and those predicted by the models was obtained. Some insights and observations with regard to the effectiveness of such a modeling approach are also presented.
Electrical contacts - 2007, the 53rd ieee holm conference on; 10/2007
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ABSTRACT: The objective of this work is to develop a greater understanding of the mechanisms controlling fretting under various vibration conditions. This information is intended to provide a basis for understanding and reducing this potential problem in automotive connectors. Toward this end, an experimental study of connector samples under multifrequency vibration has been conducted. The primary connector being investigated is a single row PC-type connector. A secondary specimen tested is a single row automotive connector
IEEE Transactions on Components and Packaging Technologies 07/2006; · 0.94 Impact Factor
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ABSTRACT: Fretting corrosion induced by vibration is a topic of major concern for automotive applications, often leading to increased contact resistance and connector failure. Presently, modeling of the behavior of connectors during fretting corrosion is a difficult matter, requiring many parameters, and is generally highly nonlinear in nature. Experimental testing of sample connectors is currently the only practical method of evaluating connector performance; however, testing can be a time-consuming and inexact task. Prior work by the authors studied the fretting behavior of connectors subjected to single frequency vibration. Correlation of experimental results with simulated behavior showed that, for the primary mode of connector interface motion observed (rocking-type motion), the relative moment at the interface was a good indicator of the observed fretting rate. It was also shown that the moment applied as the result of a given excitation level and frequency could reasonably be predicted via simulation. The current work extends this approach to random vibration profiles, which are a more realistic representation of the connector application environment. A simple model is developed which relates the early stage fretting corrosion rate to the threshold vibration levels for the connector, the dynamic characteristics of the connector/wiring configuration, and the vibration profile. A high degree of consistency between this model and the experimental data was demonstrated. Interestingly, regardless of the excitation profile applied to the overall system, the existence of a characteristic vibration threshold at the connector interface was observed.
IEEE Transactions on Components and Packaging Technologies 01/2006; · 0.94 Impact Factor
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ABSTRACT: Vibration induced fretting degradation is a widely recognized failure phenomenon; however, the basic mechanisms that control the onset and progression of such fretting behavior are not well understood and are a topic of considerable interest in the electrical connector community. One specific issue is the need for a more detailed understanding of the mechanisms controlling the fretting degradation. The present study addresses these questions and develops answers using the results from a series of experimental tests of sample connectors which are subjected to single-frequency vibration profiles at room temperature. These test specimens are a series of dual-row 16-circuit automotive connectors in which the plating finish and contact normal force are varied. The results are presented and discussed in light of earlier investigations.
Electrical Contacts, 2005. Proceedings of the Fifty-First IEEE Holm Conference on; 10/2005
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ABSTRACT: The objective of this work is to develop a greater understanding of the mechanisms controlling fretting under various vibration conditions. This information is intended to provide a basis for understanding and reducing this potential problem in automotive connectors. Toward this end, an experimental study of connector samples under multi-frequency vibration has been conducted. The primary connector being investigated is a single row PC-type connector. A secondary specimen tested is a single row automotive connector.
Electrical Contacts, 2004. Proceedings of the 50th IEEE Holm Conference on Electrical Contacts and the 22nd International Conference on Electrical Contacts; 10/2004
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ABSTRACT: Single frequency vibration tests were used to induce fretting corrosion in tin alloy plated contacts. The samples used in this study were connectors consisting of 25 pairs of mated pin and socket contacts. Experimental results for a variety of vibration levels, frequencies, and wiring tie-off lengths are presented. The experiments consisted of running a series of vibration tests at each frequency where the excitation level was stepped through a range of g-levels. During each test run contact resistance was monitored as a performance characteristic. The results exhibit threshold behavior at each frequency for the onset of fretting degradation. Typically a plateau region was observed where similar g-levels produced similar fretting rates. It was also found that outside the plateau region the g-levels varied according to the dynamic behavior of the mechanical system. In addition, a transfer matrix model was used to analyze these results. An empirical fit of the data correlated well with the model when damping was used. This analysis revealed the importance of the bending moment induced at the contact interface as a result of excitation levels and tie-off configurations. Consequently, it is concluded that dynamic response of the mechanical system under various g-levels and tie off configurations can greatly impact the performance of a connector system subjected to vibration stresses.
IEEE Transactions on Components and Packaging Technologies 04/2004; · 0.94 Impact Factor
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ABSTRACT: Single frequency vibration tests were used to induce fretting corrosion in tin alloy plated contacts. The samples used in this study were connectors consisting of 25 pairs of mated pin and socket contacts. Experimental results for a variety of vibration levels, frequencies, and wiring tie-off lengths are presented. The experiments consisted of running a series of vibration tests at each frequency where the excitation level was stepped through a range of g-levels. During each test run contact resistance was monitored as a performance characteristic. The results exhibit threshold behavior at each frequency for the onset of fretting degradation. Typically a plateau region was observed where similar g-levels produced similar fretting rates. It was also found that outside the plateau region the g-levels varied according to the dynamic behavior of the mechanical system. In addition, a transfer matrix model was used to analyze these results. An empirical fit of the data correlated well with the model when damping was used. This analysis revealed the importance of the bending moment induced at the contact interface as a result of excitation levels and tie-off configurations. Consequently, it is concluded that dynamic response of the mechanical system under various g-levels and tie off configurations can greatly impact the performance of a connector system subjected to vibration stresses.
Electrical Contacts, 2002. Proceedings of the Forty-Eighth IEEE Holm Conference on; 02/2002
