Determination of the polarization distribution in poled ferroelectric polymer by the thermal pulse method

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Simultaneous temperature and refractive index measurements using a 3°slanted multimode fiber Bragg grating

Author name used in this publication: M. S. DemokanAuthor name used in this publication: W. Jin2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Temperature-insensitive interferometer using a highly birefringent photonic crystal fiber loop mirror

Author name used in this publication: M. S. Demokan2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Kinetics of thermal oxidation of 6H silicon carbide in oxygen plus trichloroethylene

In this work, the behaviors of the trichloroethylene (TCE) thermal oxidation of 6H silicon carbide (SiC) are investigated. The oxide growth of 6H SiC under different TCE concentrations (ratios of TCE to O2) follows the linear-parabolic oxidation law derived for silicon oxidation by Deal and Grove, J. Appl. Phys., 36 (1965). The oxidation rate with TCE is much higher than that without TCE and strongly depends on the TCE ratio in addition to oxidation temperature and oxidation time. The increase in oxidation rate induced by TCE is between 2.7 and 67% for a TCE ratio of 0.001-0.2 and a temperature of 1000-1150°C. Generally, the oxidation rate increases quickly with the TCE ratio for a TCE ratio less than 0.05 and then gradually saturates for a ratio larger than 0.05. The activation energy EB/A of the TCE oxidation for the TCE ratio range of 0.001-0.2 is 1.04-1.05 eV, which is a little larger than the 1.02 eV of dry oxidation. A two-step model for the TCE oxidation is also proposed to explain the experimental results. The model points out that in the SiC oxidation with TCE, the products (H2O and Cl2) of the reaction between TCE and O2 can speed up the oxidation, and hence, the oxidation rate is highly sensitive to the TCE ratio. © 2005 The Electrochemical Society. All rights reserved.published_or_final_versio

Effect of a nonlinear photonic crystal fiber on the noise characterization of a distributed Raman amplifier

Author name used in this publication: M. S. Demokan2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Magnetoelectric photocurrent generated by direct interband transitions in InGaAs/InAlAs two-dimensional electron gas

We report the observation of magnetoelectric photocurrent generated via direct interband transitions in an InGaAs/InAlAs two-dimensional electron gas by a linearly polarized incident light. The electric current is proportional to the in-plane magnetic field, which unbalances the velocities of the photoexcited carriers with opposite spins and consequently generates the electric current from a hidden spin photocurrent. The spin photocurrent can be evaluated from the measured electric current, and the conversion coefficient of spin photocurrent to electric current is self-consistently estimated to be 10-3-10 -2 per Tesla. The observed light-polarization dependence of the electric current is well explained by a theoretical model which reveals the wave vector angle dependence of the photoexcited carrier density. © 2010 The American Physical Society.published_or_final_versio

Studies on strain and temperature characteristics of a slanted multimode fiber Bragg grating and its application in multiwavelength fiber Raman ring laser

Author name used in this publication: M. S. Demokan2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

First two cases of living related liver transplantation with complicated anatomy of blood vessels in Beijing

Aim: Living related liver transplantation (LRLT) has been developed in response to the paediatric organ donor shortage. Though it has been succeeded in many centers worldwide, the safety of the donor is still a major concern, especially in donors with anatomy variation. We succeeded in performing the first two cases of living related liver transplantation with complicated anatomy of blood vessels as a way to overcome cadaveric organ shortage in Beijing. Methods: Two patients, with congenital liver fibrosis and congenital biliary atresia were performed with living donor liver transplantation in our hospital and then followed up from November 12 to December 13, 2001. The two living donors, mother and father, were healthy aged 34 and 35 years. One right lobe (segment V, VI, VII, VIII) and one left lateral lobe (segment II and III) were used. The grafts weighed 394 g and 300 g. The ratio of graff weight to the standard liver volume (SLV) of donors was 68% and 27%. The graft weight to recipient body weight ratio was 3.2% and 4.4%. The graft weight to recipient estimated standard liver mass (ESLM) ratio was 63% and 85%. The two donors had complicated blood vessel variation. Results: Two patients undergone living donor liver transplantation had good results. Abnormal liver function with high bilirubin level appeared in a few days after operation, bur liver function returned to normal one month after operation with bilirubin level almost decreased to near normal. No bleeding, thrombosis, infection and bile leakage occurred. One had an acure rejection and recovered. The two donors recovered in two weeks. One had slight fever because of a little collection in abdomen and recovered after paracentesis and drainage. Conclusion: Living donor liver transplantation has been proved to be a good way that offers a unique opportunity of getting a timely liver graft as a response to shortage of pediatric donors, though it could be a technically difficult operation if there is anatomical variation. Copyright © 2004 by The WJG Press.published_or_final_versio

Analysis of Surface Electromyography for On-Off Control

Myogram on-and-off controller is important for improving or assisting the elderly people. One of the most important aspects of the controller development is to determine the on and off time with respect to the body movement. In this project, high accuracy signal filtering, high gain amplifier, signal converter, microcontroller and electrodes are used for circuit simulation and development to obtain muscle signal (Electromyogram). Precision rectifier is used to solve the ordinary semiconductor problem to avoid signal block. To ensurethe user-friendliness in the development of this device, non-invasive electrodes are used in this project instead of invasive electrodes

Integrin-mediated interactions with extracellular matrix proteins for nucleus pulposus cells of the human intervertebral disc.

The extracellular matrix (ECM) of the human intervertebral disc is rich in molecules that interact with cells through integrin-mediated attachments. Porcine nucleus pulposus (NP) cells have been shown to interact with laminin (LM) isoforms LM-111 and LM-511 through select integrins that regulate biosynthesis and cell attachment. Since human NP cells lose many phenotypic characteristics with age, attachment and interaction with the ECM may be altered. Expression of LM-binding integrins was quantified for human NP cells using flow cytometry. The cell-ECM attachment mechanism was determined by quantifying cell attachment to LM-111, LM-511, or type II collagen after functionally blocking specific integrin subunits. Human NP cells express integrins β1, α3, and α5, with over 70% of cells positive for each subunit. Blocking subunit β1 inhibited NP cell attachment to all substrates. Blocking subunits α1, α2, α3, and α5 simultaneously, but not individually, inhibits NP cell attachment to laminins. While integrin α6β1 mediated porcine NP cell attachment to LM-111, we found integrins α3, α5, and β1 instead contributed to human NP cell attachment. These findings identify integrin subunits that may mediate interactions with the ECM for human NP cells and could be used to promote cell attachment, survival, and biosynthesis in cell-based therapeutics