A Novel AFM-MEA Platform for Studying the Real Time Mechano-Electrical Behavior of Cardiac Myocytes

2010 ◽  
Vol 1261 ◽  
Author(s):  
Jose Francisco Saenz Cogollo ◽  
Mariateresa Tedesco ◽  
Sergio Martinoia ◽  
Roberto Raiteri
Keyword(s):  
Elastic Modulus ◽  
Cardiac Myocytes ◽  
Electrical Response ◽  
Electrode Array ◽  
Maximum Load ◽  
Dynamic Elastic Modulus ◽  
Relaxation Cycle ◽  
Relaxation Phase ◽  
Cell Height ◽  
Set Up

AbstractWe present a novel experimental platform based on a combined Atomic Force Microscopy (AFM) and Micro-Electrode Array (MEA) set-up. We have used it to measure minimal changes in the morphological/mechanical properties of electrically active cell cultures as well as to measure the changes in the extracellular electrical activity when a single cell is stimulated by means of the AFM tip. In particular, we studied the dynamical changes in cell elasticity of embryonic rat cardiac myocytes along the contraction-relaxation cycle. Applying high load indentations, we also recorded the effects of mechanical stimulations on the cell electrophysiology. The dynamic elastic modulus of the cell related to the contraction-relaxation cycle reveals a temporal behavior that closely follows the changes in cell height. Observed values of dynamic elastic modulus at a maximum indentation depth of 1500nm varied between 8.93 ± 0.78 kPa during systolic (contraction) phase and 4.26 ± 0.47 kPa during diastolic (relaxation) phase. Induced electrophysiological responses were observed when applying loads in the range 40-150 nN. The probability P of recording an induced electrical response (P = 0.16 for a maximum load of 100nN) increased with the maximum applied load. Pulling-like stimulations due to the tip-cell adhesion could also evocate electrical responses.

Influence of Water Content on Dynamic Elastic Modulus of Concrete

2013 ◽  
Vol 351-352 ◽  
pp. 1605-1609
Author(s):  
Fang Zhi Zhu ◽  
Tie Jun Zhao ◽  
Ting Guan
Keyword(s):  
Elastic Modulus ◽  
Water Content ◽  
Damage Assessment ◽  
Dynamic Elastic Modulus ◽  
Bending Vibration ◽  
Assessment Index ◽  
Content Change ◽  
Influence Of Water ◽  
Set Up ◽  
Low Sensitivity

Water content is one of key effect factors on the dynamic elastic modulus, which is an important damage assessment index of concrete structures induced by freeze-thaw cycles, fire and chemical attacks. Through the ultrasonic and bending vibration test, the regularity of dynamic elastic modulus changed with the water content of concrete specimens was analyzed in this paper. The results show that the ultrasonic velocity has a low sensitivity to water content when it is below 1.5%. The bending vibration method can better reflect the effect of water content change on dynamic elastic modulus. The regression equation of dynamic elastic modulus and water content was set up by introducing the index function. The research results offer technical reference for the predicting of actual concrete dynamic elastic modulus in different humidity environment.

scholarly journals EEG-based diagnostics of the auditory system using cochlear implant electrodes as sensors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ben Somers ◽  
Christopher J. Long ◽  
Tom Francart
Keyword(s):  
Cochlear Implant ◽  
Auditory Evoked Potentials ◽  
Human Subjects ◽  
Electrode Array ◽  
Brain Regions ◽  
Hearing Impaired ◽  
Brain Responses ◽  
Listening Environments ◽  
Set Up ◽  
Neural Feedback

AbstractThe cochlear implant is one of the most successful medical prostheses, allowing deaf and severely hearing-impaired persons to hear again by electrically stimulating the auditory nerve. A trained audiologist adjusts the stimulation settings for good speech understanding, known as “fitting” the implant. This process is based on subjective feedback from the user, making it time-consuming and challenging, especially in paediatric or communication-impaired populations. Furthermore, fittings only happen during infrequent sessions at a clinic, and therefore cannot take into account variable factors that affect the user’s hearing, such as physiological changes and different listening environments. Objective audiometry, in which brain responses evoked by auditory stimulation are collected and analysed, removes the need for active patient participation. However, recording of brain responses still requires expensive equipment that is cumbersome to use. An elegant solution is to record the neural signals using the implant itself. We demonstrate for the first time the recording of continuous electroencephalographic (EEG) signals from the implanted intracochlear electrode array in human subjects, using auditory evoked potentials originating from different brain regions. This was done using a temporary recording set-up with a percutaneous connector used for research purposes. Furthermore, we show that the response morphologies and amplitudes depend crucially on the recording electrode configuration. The integration of an EEG system into cochlear implants paves the way towards chronic neuro-monitoring of hearing-impaired patients in their everyday environment, and neuro-steered hearing prostheses, which can autonomously adjust their output based on neural feedback.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

scholarly journals Assessment of the Deterioration State of Post-Installed Bonded Anchors Using Ultrasonic

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2077
Author(s):  
Oliver Zeman ◽  
Michael Schwenn ◽  
Martin Granig ◽  
Konrad Bergmeister
Keyword(s):  
Maximum Load ◽  
Assessment Method ◽  
Load Level ◽  
Experimental Investigations ◽  
Load History ◽  
Anchor System ◽  
Ultrasonic Methods ◽  
Building Maintenance ◽  
History Of ◽  
Set Up

The assessment of already installed anchorages for a possible exceeding of the service load level is a question that is gaining more and more importance, especially in building maintenance. Bonded anchors are of particular interest here, as the detection of a capacity reduction or load exceedance can cause damage to the concrete-bonded mortar behavior. This article investigates the extent to which ultrasonic methods can be used to make a prediction about the condition of anchorages in concrete and about their load history. A promising innovative assessment method has been developed. The challenges in carrying out the experimental investigations are the arrangement of the transducers, the design of the test set-up and the applicability of direct, indirect or semidirect ultrasonic transmission. The experimental investigations carried out on a test concrete mix and a bonded anchor system show that damage to the concrete structure can be detected by means of ultrasound. The results indicate the formation of cracks and therefore a weakening of the response determined by means of direct, indirect and semidirect ultrasonic transmission. However, for application under non-laboratory conditions and on anchors with unknown load history, the calibration with a reference anchor and the identification of the maximum load is required. This enables a referencing of the other loaded anchors to the unloaded conditions and allows an estimation of the load history of individual anchors.

scholarly journals Use of Silica Fume and GGBS to Improve Frost Resistance of ECC with High-Volume Fly Ash

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yushi Liu ◽  
Xiaoming Zhou ◽  
Chengbo Lv ◽  
Yingzi Yang ◽  
Tianan Liu
Keyword(s):  
Elastic Modulus ◽  
Sodium Chloride ◽  
Mass Loss ◽  
Frost Resistance ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Tap Water ◽  
High Volume ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw

Fly ash (FA) has been an important ingredient for engineered cementitious composite (ECC) with excellent tensile strain capacity and multiple cracking. Unfortunately, the frost resistance of ECC with high-volume FA has always been a problem. This paper discusses the influence of silica fume (SF) and ground-granulated blast-furnace slag (GGBS) on the frost resistance of ECC with high volume of FA. Four ECC mixtures, ECC (50% FA), ECC (70% FA), ECC (30% FA + 40% SL), and ECC (65% FA + 5% SF), are evaluated by freezing-thawing cycles up to 200 cycles in tap water and sodium chloride solution. The result shows the relative dynamic elastic modulus and mass loss of ECC in sodium chloride solution by freeze-thaw cycles are larger than those in tap water by freeze-thaw cycles. Moreover, the relative dynamic elastic modulus and mass loss of ECC by freeze-thaw cycles increase with FA content increasing. However, the ECC (30% FA + 40% SL) shows a lower relative dynamic elastic modulus and mass loss, but its deflection upon four-point bending test is relatively smaller before and after freeze-thaw cycles. By contrast, the ECC (65% FA + 5% SF) exhibits a significant deflection increase with higher first cracking load, and the toughness increases sharply after freeze-thaw cycles, meaning ECC has good toughness property.

scholarly journals Study on the Mechanical Properties of Chlorine Saline Soil under the Interaction of Multiple Factors

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Anhua Xu ◽  
Pengcheng Wang ◽  
Jianhong Fang
Keyword(s):  
Elastic Modulus ◽  
Moisture Content ◽  
Mechanical Characteristics ◽  
External Environment ◽  
Confining Pressure ◽  
Dynamic Elastic Modulus ◽  
Dynamic Strain ◽  
Saline Soils ◽  
Loading Frequency ◽  
Failure Strength

The distribution of chlorine saline soils is extensive in Haixi region of Qinghai Province in Northwest China. Its natural and geographical conditions are unique, and the external environment varies greatly. To study the effects of variable external environment on the mechanical characteristics of chlorine saline soils, a number of unconsolidated undrained (UU) dynamic triaxial tests under different confining pressure, moisture content, and loading frequency were carried out. The dynamic stress–dynamic strain, failure strength, dynamic elastic modulus, and parameter of shear strength were analyzed. The triaxial test results demonstrated that the stress–strain curves of the soil were strain-hardening. The failure strength and dynamic elastic modulus increased with the increasing of confining pressure; the law with moisture content and loading frequency were inconsistent. The dynamic cohesion and dynamic friction angle increased with the increasing of loading frequency, but decreased with the increasing of moisture content. Besides, the significance analysis theory was used to analyze the effect degree of different factors. It found that the effects of confining pressure, loading frequency, and the interaction between confining pressure and frequency on mechanical characteristics were significant, but the moisture content had less effect.

Sign in / Sign up

Export Citation Format

Share Document