检索结果-内蒙古大学图书馆

IEEE Symposium (IUS) Ultrasonics

作者： R. S. Singh M. Culjat R. R. Neurgaonkar S. N. White W. S. Grundfest E. R. Brown Department of Electrical and Computer Engineering University of California Santa Barbara Santa Barbara CA USA Department of Surgery UCLA Los Angeles CA USA Sonatech Inc. Santa Barbara CA USA School of Dentistry Santa Barbara CA USA Department of BioEngineering UCLA Los Angeles CA USA

Hard tissue medical imaging and other applications such as IC-chip package inspection present a series of challenges for ultrasound imaging, including small feature size, high acoustic clutter, and high acoustic impedances. We report here on the design and performance of a 19 MHz resonant thickness mode, ceramic PLZT (Lead Lanthanum Zirconate Titanate) transducer designed for high acoustic impedance (>10 MRayl) operation in the presence of acoustic clutter. One-dimensional transducer analysis using the Mason model is also presented and is used to predict the expected bandwidth and center operating frequency, and to compare PLZT and PZT-5H in our transducer design. The packaged transducer features a high impedance matching layer and a gallium-indium alloy couplant (17.4 MRayl), which together minimize surface clutter due to impedance mismatches. The transducer has a narrow 8deg -3 dB full beamwidth, a 30% instantaneous bandwidth, and a narrow pulse width (250 ns), resulting in high lateral (210 mum at 1.5 mm) and axial (350 mum in gallium-indium alloy) resolutions for detection of small features. The transducer has been integrated with a match filter receiver, and the system has been demonstrated to obtain a single pulse SNR of 45 dB in detecting a 25 mum thick crack in the highly cluttered environment of a human tooth. The Mason model predicts that the PLZT transducer has a 50% higher bandwidth than an equivalent PZT-5H transducer, in large part because of the increased electromechanical coupling coefficient (PLZT k ap 0.82, and PZT-5H k t ap 0.65). The tradeoff is ~30% lower acoustic-to-electric responsivity caused primarily by a larger dielectric constant. This is not so significant in the present applications (solid-state imaging), which tend to have clutter-limited environments. However, the improved bandwidth is very useful in improving range resolution and in gating out unwanted echoes, including those from the clutter

关键词： Solids Acoustic transducers Bandwidth Gallium alloys Ultrasonic transducers Acoustic imaging Ultrasonic imaging Biomedical transducers Packaging Acoustic applications

来源：评论

学校读者我要写书评

暂无评论

Swelling characterization of anionic acrylic acid hydrogel in an external electric field

引用

Iranian Polymer Journal (English Edition) 2006年第11期15卷 891-900页

作者： Tavakoli, Javad Jabbari, Esmaiel Khosroshahi, Mohammad Etrati Boroujerdi, Mina Biomaterial Group Bioengineering Faculty Amirkabir University of Technology P.O. Box: 15875/4413 Tehran Iran Department of Chemical Engineering South Carolina University Columbia 29208 United States Bioelectric Group Electrical and Computer Science Faculty Tehran University P.O. Box: 14395-515 Tehran Iran

A polymer gel is a cross-linked polymer which undergoes a reversible volume and/or sol-gel phase transition in response to physiological (temperature, pH and presence of ion in organism fluids) or other external (electric field, light) stimuli. In structurally soft gels, the motion of polymer network and the diffusion of ions easily take place by an external stimulus. A typical function of gel containing ionic groups is to swell under the influence of an electric field, making it useful for wide biomedical applications. In this study, poly(acrylic acid) (PAA) hydrogel network was prepared by free radical polymerization whose average molecular weight between crosslinkes was calculated as 18500 g/mol and its homogeneity assessment evaluated by comparing 30 samples swelling ratios after 48 h soaking in distilled deionized water. The swelling behaviour of PAA under an electric field application was also investigated as a function of cross-linking agent and electric field intensity variation. It is seen that equilibrium swelling ratio of PAA gel increases from 16 (no electric field) to 30 (by application of 300 V/m electric field), however this variation is dependent on the sample location relative to electrodes. The normalized swelling ratio of sample changes by 4.8 to 0.9 relative to its distance from positive electrode. Increasing the concentration of cross-linking agent (EGDMA) from 0.14 to 0.71 molar percent of monomer resulted in 45% decrease of gel volume fraction. It is proven that applying an external electric field can make an improvement in the time-response of the hydrogel expansion phase and swelling behaviour.

关键词： Hydrogels

来源：评论

学校读者我要写书评

暂无评论

Prediction of Driving Ability in Persons with Brain Disorders using Sensory-Motor and Cognitive Tests

Prediction of Driving Ability in Persons with Brain Disorder...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： C.R.H. Innes R.D. Jones T.J. Anderson J.C. Dalrymple-Alford S. Hayes S. Hollobon J. Severinsen G. Smith A. Nicholls Department of Medicine Christchurch School of Medicine and Health Sciences University of Otago Christchurch New Zealand Department of Electrical and Computer Engineering University of Canterbury Christchurch New Zealand Department of Medical Physics & Bioengineering Christchurch Hospital Christchurch New Zealand Department of Neurology Christchurch Hospital Christchurch New Zealand Department of Psychology University of Canterbury Christchurch New Zealand Department of Occupational Therapy Burwood Hospital Christchurch New Zealand

Brain lesions and degeneration can lead to a decreased ability to perform the physical and cognitive functions necessary for safe driving. A battery of computerized sensory-motor and cognitive tests (SMCTeststrade) has been developed to quantify sensory-motor and cognitive dysfunction, with particular application to the assessment of driving abilities in patients with neurological disorders. SMCTests and an on-road driving assessment were applied to 50 subjects with brain lesions referred to the Driving and Vehicle Assessment Service at Burwood Hospital, Christchurch (36 males, 14 females; age range 43-85 years, mean age 71.3 years; 35 stroke, 4 traumatic brain injury, 4 Alzheimer's disease, 7 with other diagnoses). Two techniques were used to build model equations for prediction of on-road driving ability based on SMCTests performance - binary logistic regression and nonlinear causal resource analysis (NCRA). Binary logistic regression correctly classified 94% of referrals as on-road pass or fail, while NCRA correctly classified 90% of referrals. Leave-one-out cross-validation analysis estimated that binary logistic regression would correctly predict the classification of 86% of an independent referral group as on-road pass or fail, while NCRA would correctly predict 76%. Results indicate that the predictive model based on binary logistic regression would be slightly more accurate than NCRA at predicting on-road pass or fail in an independent subject group. Conversely, the NCRA model also provides valuable information on the extent to which a subject would pass or fail an on-road driving assessment and identifies the deficit which most limits their driving ability

关键词： Testing Logistics Lesions Predictive models Batteries Application software Vehicle driving Hospitals Brain injuries Alzheimer's disease

来源：评论

学校读者我要写书评

暂无评论

Measurements of electrophysiological effects of components of acute ischemia in Langendorff-perfused rat hearts using voltage-sensitive dye mapping

引用

Journal of Cardiovascular Electrophysiology 2006年第SUPPL. 1期17卷 S113-S123页

作者： Nygren, Anders Baczkó, István Giles, Wayne R. Department of Physiology and Biophysics University of Calgary Calgary Alta. Canada Whitaker Institute of Biomedical Engineering University of California San Diego San Diego CA United States Centre for Bioengineering Research and Education Department of Computer and Electrical Engineering University of Calgary Calgary Alta. Canada Whitaker Institute of Biomedical Engineering PFBG 384 University of California San Diego San Diego CA 92093-0412 9500 Gilman Dr United States

Introduction: This study was carried out to evaluate optical mapping in the presence of cytochalasin-D as a method for measuring electrophysiological responses in general, and in particular the responses to acute ischemia in the Langendorff-perfused rat heart. Cytochalasin-D is commonly used to reduce contraction for the purpose of suppressing motion artifacts in voltage-sensitive dye recordings of cardiac membrane potential. Methods and Results: Observations using optical mapping were complemented by recordings of the surface electrogram to provide information independent of the optical measurements. Perfusion of Langendorff-perfused rat hearts with 3 μM cytochalasin-D resulted in a 24% prolongation of the QT interval of surface electrograms indicating that cytochalasin-D prolongs the rat ventricular action potential. Individual components of the electrophysiological response to acute ischemia were globally induced as follows: (1) opening of K_ATP channels was induced by perfusion of 2 μM P-1075, (2) accumulation of extracellular K⁺ was simulated by increasing perfusate [K⁺] to 12 mM, and (3) acidosis was simulated by reducing perfusate pH to 6.5. The responses to these interventions could be reliably documented using optical recordings, as well as from surface electrograms. Whole-cell patch clamp measurements on isolated rat ventricular myocytes indicate that cytochalasin-D produces an approximately 2.5-fold increase in P-1075-induced I_K,ATP. Conclusion: These results provide the necessary background information for interpreting electrophysiological measurements during acute ischemia in the presence of cytochalasin-D.

关键词： Cytochalasin-D Fluorescent dye imaging Ischemia Optical mapping

来源：评论

学校读者我要写书评

暂无评论

Chitosan for Biofunctionalization of Microsystems

Chitosan for Biofunctionalization of Microsystems

引用

IEEE/NLM Life Science Systems and Applications Workshop

作者： Stephan T. Koev Michael A. Powers Vlad Badilita Hyunmin Yi William E. Bentley Gregory F. Payne Gary W. Rubloff Reza Ghodssi Institute for Systems Research ISR University of Maryland College Park MD USA University System of Maryland Adelphi MD US Department of Materials Science and Engineering University of Maryland College Park MD USA Department of Chemical Engineering University of Maryland College Park MD 20742 University of Maryland Biotechnology Institute (UMBI) University of Maryland College Park MD 20742 Bioengineering Graduate Program University of Maryland College Park MD 20742 University of Maryland College Park MD USA University of Maryland Biotechnology Institute College Park MD USA Institute for Systems Research (ISR) University of Maryland College Park MD 20742 Department of Materials Science and Engineering University of Maryland College Park MD 20742 Department of Electrical and Computer Engineering University of Maryland College Park MD 20742 Institute for Systems Research (ISR) University of Maryland College Park MD 20742

ISBN: (纸本)1424402778

We present the use of the polysaccharide chitosan for immobilizing biomolecules on microfabricated device surfaces. The main advantages of chitosan are its abundance of primary amine groups and its ability to be electrodeposited. Biomolecules are easily attached to chitosan 's amines by standard glutaraldehyde chemistry. The electrodeposition of chitosan allows accurate spatial and temporal control of biomolecule placement. We have demonstrated this biofunctionalization method for two different bioMEMS devices: a biophotonic sensor and a micromechanical biosensor. We have successfully assembled probe DNA on each of them and detected hybridization with target DNA as a demonstration of sensor operation. Here, we briefly present the fabrication procedure and testing results for both of these bioMEMS sensing devices

关键词： DNA Biosensors Molecular biophysics Probes Micromechanical devices Optical sensors Optical surface waves Optical interferometry Assembly Biomedical optical imaging

来源：评论

学校读者我要写书评

暂无评论

Optical and electrical properties of colloidal quantum dots in electrolytic environments: Using biomolecular links in chemically-directed assembly of quantum dot networks

引用

Journal of Computational Electronics 2005年第1-2期4卷 21-25页

作者： Stroscio, Michael A. Dutta, Mitra Ramadurai, Dinakar Shi, Peng Li, Yang Vasudev, Milana Alexson, Dimitri Kohanpour, Babak Sethuraman, Akil Saini, Vikas Raichura, Amit Yang, Jianyong Department of Bioengineering University of Illinois at Chicago Chicago IL 60607 United States Department of Electrical and Computer Engineering

The threshold of the absorption spectra of colloidal cadmium sulfide (CdS) quantum dots in electrolytic solutions is shown to shift as the concentration of the electrolyte is varied. The shift in the absorption threshold as a function of the electrolytic concentration is given by electrolytic screening of the field caused by the intrinsic spontaneous polarization of these würtzite quantum dots. These electrolyte-dependent absorption properties are compared with Fermi-level tuning in carbon nanotubes in electrolytic environments. Moreover, concepts for integrating such colloidal quantum dots in high density networks with biomolecular links are discussed. Such biomolecular links are used to facilitate the chemically-directed assembly of quantum dots networks with densities approximating 10¹⁷ cm^-3. © 2005 Springer Science + Business Media, Inc.

关键词： Biomolecules Electrochemical tuning Integrated ensembles of nanostructures Quantum dots

来源：评论

学校读者我要写书评

暂无评论

3D multiwavelet-based motion residual compression for neurosurgical monitoring videos

3D multiwavelet-based motion residual compression for neuros...

引用

2005 IEEE 7th Workshop on Multimedia Signal Processing, MMSP 2005

作者： Chien, Jong-Chih Li, C.C. Sun, Mingui Department of Electrical and Computer Engineering University of Pittsburgh Pittsburgh United States Departments of Neurosurgery Electrical and Computer Engineering and Bioengineering University of Pittsburgh Pittsburgh United States

ISBN: (纸本)0780392892

Neurophysical Interoperative Monitoring (OEM) video is an important tool in biomedical applications and telemedicine and it is essential to maintain high fidelity of the frames even in low bit-rate environment. Toward this end, we studied a spatio-temporal 3D multiwavelet-based OIM video compression system that is capable of high quality output even under the demands of high compression ratios.

关键词： Wavelet analysis

来源：评论

学校读者我要写书评

暂无评论

Improved optical design for fast scanning RMA

Improved optical design for fast scanning RMA

引用

Frontiers in Optics, FiO 2005

作者： Chen, Nan Guang Liu, Linbo Division of Bioengineering and Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

A double-pass rotary mirror array has been developed for fast scanning optical delay line with a scanning range over 3 mm. Such a device is ideal for real-time optical coherence tomography and optical Doppler tomograp... 详细信息

ISBN: (纸本)1557527970

关键词： Optical design

来源：评论

学校读者我要写书评

暂无评论

Thermal Analysis of Catheter Antennas for Microwave Ablation Therapy 16

Thermal Analysis of Catheter Antennas for Microwave Ablation...

引用

16th International Zurich Symposium on Electromagnetic Compatibility, EMC 2005

作者： Pisa, Stefano Cavagnaro, Marta Piuzzi, Emanuele Bernardi, Paolo Lin, James C. "La Sapienza" University of Rome Department of Electronic Engineering Rome Italy University of Illinois at Chicago Department of Bioengineering Department of Electrical and Computer Engineering Chicago United States

ISBN: (纸本)3952119997

In this paper, a study of two MW ablation antennas, one designed for cardiac ablation and the other for endometrial ablation, has been performed. Homogeneous phantoms have been used to compare numerical and experimental results, while two–layer phantoms have been considered to better model the biological reality. Results have been obtained in terms of the required power and application time as a function of the lesion depth to be obtained. © EMC *** rights reserved.

关键词： Phantoms

来源：评论

学校读者我要写书评

暂无评论

Integrated driving and readout circuits for CDMPI sensor

Integrated driving and readout circuits for CDMPI sensor

引用

INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference

作者： Qian, X.-B. Li', X.P. Xu, Y.P. Fan, J. Department of Mechanical Engineering Division of Bioengineering National University of Singapore Singapore 117576 Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

No abstract available

ISBN: (纸本)0780390091

No abstract available

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：