Digital Commons Network^™

Mechanisms Of Left Ventricular Thrombus Formation In Heart Failure With Reduced Ejection Fraction: Novel Insights From Two-Dimensional Speckle Tracking Echocardiography, Dhruv Chawla, Tracy Hammonds, Tadele Mengesha, Matt Umland, Khawaja Afzal Ammar, Vinay Thohan

Aurora Heart Failure / Transplant Faculty

Background: Patients suffering from heart failure with reduced ejection fraction (HFrEF) are at increased risk for left ventricular (LV) thrombus and subsequent thromboembolism, yet anticoagulation is not routinely recommended for left ventricular ejection fraction (LVEF) alone. We sought to determine the role of two-dimensional speckle tracking echocardiography (2D-STE) to quantify regional changes in cardiac function associated with LV thrombus, which may prospectively guide anticoagulation.

Purpose: Help enable cardiovascular clinicians to use 2D-STE to evaluate regional strain patterns among patients with HFrEF with and without LV thrombus. Our results suggest that statistically lower regional longitudinal strain patterns in a well-matched cohort …

Interface Strain-Induced Multiferroicity In A Smfeo3 Film, Zhenxiang Cheng, Fang Hong, Yuanxu Wang, Kiyoshi Ozawa, Hiroki Fujii, Hideo Kimura, Yi Du, Xiaolin Wang, S X. Dou

Shi Xue Dou

An epitaxial pseudocubic SmFeO3 thin film on (100) Nb-SrTiO 3 was studied based on ferroelectric (FE) characterization and magnetic measurements. High-resolution transmission electron microscopy images clarify the nature of the epitaxial growth, the stress-induced structural distortion at the film/substrate interface, and the existence of two different orientation lattices. Clear grain boundaries can be seen, which could introduce an extra local distortion. Rectangular FE loops can be observed at room temperature, even by just applying a small voltage ranging from -1 to +1 V, indicative of the presence of FE polarization. Piezoelectric force microscopy images confirm the existence of FE domains …

The Effect Of The Strain Rate On Soft Soil Behaviour Under Cyclic Loading, Jing Ni, Buddhima Indraratna, X Y. Geng, Cholachat Rujikiatkamjorn

Cholachat Rujikiatkamjorn

In this paper, cyclic triaxial loading tests were conducted on specimens of soft clay with varying cyclic stresses and frequencies to investigate the performance of soft soil subgrade subjected to cyclic loading. The laboratory results indicate that given the same level of cyclic stress, the stability of clay subgrade is primarily dependent on the loading time with no consistent frequency/train speed effect. There exists a critical level of cyclic stress between 60 and 80% of the monotonic shear strength, above which failure may occur regardless of the loading frequency. The nature that soils behave dependently on cyclic stress level rather …

Laboratory Study Of Small-Strain Behavior Of A Compacted Silty Sand, Ana Heitor, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Cholachat Rujikiatkamjorn

Small-strain behavior is a key indicator for assessing the performance of compacted fills. Compaction conditions, i.e., initial moisture content and applied energy, govern compaction effectiveness and thus, the structure and matric suction of compacted soil. This paper presents an experimental study of the small-strain behavior of compacted silty sand prepared with different compaction conditions. Specimens with varying initial moisture contents and compaction energies were tested with bender elements to determine the small-strain shear modulus (G0), while the post-compaction matric suction was measured using the filter paper method and tensiometer. The experimental data suggest a pronounced relationship between G0 and the …

Stress-Strain Degradation Response Of Railway Ballast Stabilized With Geosynthetics, Buddhima Indraratna, Sanjay Nimbalkar

Buddhima Indraratna

Large cyclic loading on ballasted railroad tracks is now inevitable owing to an increased demand for freight and public transport. This leads to a progressive deterioration and densification of railroad ballast and consequently to the loss of track geometry and differential settlement. Understanding these complex stress-strain and degradation mechanisms is essential to predict the desirable track maintenance cycle, as well as the design of new track. This paper presents the results of cyclic drained tests and numerical studies carried out on a segment of model railway track supported on geosynthetically reinforced railroad ballast bed. The relative performance and effectiveness of …

Effects Of Fouling On The Stress-Strain-Degradation Behaviour Of Rail Ballast, Buddhima Indraratna, Nayoma C. Tennakoon, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn

Buddhima Indraratna

Ballast is most commonly used as a structural component of rail track due to its high load bearing capacity, resiliency and rapid drainage. However, ballast along coal freight corridors often becomes fouled due to spilling of coal from moving wagons, in addition to further track deterioration attributed to particle breakage and pumping of soft subgrade. Highly fouled ballast needs to be cleaned or replaced to maintain the desired track resiliency, load bearing capacity and the track alignment. In order to identify the risk associated with fouling, it is important to accurately assess the amount of fouling. In this paper, the …

Laboratory Study Of Small-Strain Behavior Of A Compacted Silty Sand, Ana Heitor, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Buddhima Indraratna

Small-strain behavior is a key indicator for assessing the performance of compacted fills. Compaction conditions, i.e., initial moisture content and applied energy, govern compaction effectiveness and thus, the structure and matric suction of compacted soil. This paper presents an experimental study of the small-strain behavior of compacted silty sand prepared with different compaction conditions. Specimens with varying initial moisture contents and compaction energies were tested with bender elements to determine the small-strain shear modulus (G0), while the post-compaction matric suction was measured using the filter paper method and tensiometer. The experimental data suggest a pronounced relationship between G0 and the …

Tensile Testing Of Individual Glassy, Rubbery And Hydrogel Electrospun Polymer Nanofibres To High Strain Using The Atomic Force Microscope, Adrian Gestos, Philip G. Whitten, Geoffrey M. Spinks, Gordon G. Wallace

Gordon Wallace

The production and use of polymer nanofibre assemblies prepared by electrospinning is now widespread. It is known that the tensile properties of electrospun polymer fibres can be different to those of bulk polymers. Here, we report a general method for measuring the tensile properties of individual electrospun nanofibres that employs a commercial atomic force microscope. Methods for preparing samples, force calibration and calculation of tensile stress and strain are described along with error estimation. By appropriate choice of AFM cantilever, it is shown that the tensile stress-strain curves can be measured for glassy, rubbery and gel polymer nanofibres. Testing can …

High Strain Stretchable Solid Electrolytes, Sureyya Saricilar, Dennis Antiohos, Kewei Shu, Philip G. Whitten, Klaudia Wagner, Caiyun Wang, Gordon G. Wallace

Gordon Wallace

Wearable electronic devices that can be integrated seamlessly into clothing for monitoring and feedback need to be not only flexible, but also stretchable with low stiffness. Currently there are few solid electrolytes that are sufficiently stretchable for wearable electronic devices. Here we report stretchable solid electrolytes that can be elastically stretched more than 500% of their original length with ionic conductivities as high as 7 x 10(-5) S cm(-1) and tensile breaking strengths larger than 1.5 MPa. These solid electrolytes consist of poly(methyl methacrylate) chemical networks solvated by an electrochemically stable ionic liquid. A stretchable supercapacitor was demonstrated by coating …

Hindlimb Function In The Alligator: Integrating Movements, Motor Patterns, Ground Reaction Forces And Bone Strain Of Terrestrial Locomotion, Stephen M. Reilly, Jeffrey S. Wiley, Audrone R. Biknevicius, Richard W. Blob

R. W. Blob

Alligator hindlimbs show high torsional loads during terrestrial locomotion, in sharp contrast to the bending or axial compressive loads that predominate in animals that use parasagittal limb movements. The present study integrates new data on hindlimb muscle function with previously obtained data on hindlimb kinematics, motor patterns, ground reaction forces and bone strain in order to (1) assess mechanisms underlying limb bone torsion during non-parasagittal locomotion in alligators and (2) improve understanding of hindlimb dynamics during terrestrial locomotion. Three dynamic stance phase periods were recognized: limb-loading, support-and-propulsion, and limb-unloading phases. Shear stresses due to torsion were maximized during the limb-loading …

Atomistic Simulation Of Realistically Sized Nanodevices Using Nemo 3-D - Part Ii: Applications, Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, Marta Prada, Timothy Boykin

Gerhard Klimeck

In Part 1, the development and deployment of a general nanoelectronic modeling tool (NEMO 3-D) has been discussed. Based on the atomistic valence-force field and the sp(3)d(5)s*. nearest neighbor tight-binding models, NEMO 3-D enables the computation of strain and electronic structure in nanostructures consisting of more than 64 and 52 million atoms, corresponding to volumes of (110 nm)(3) and (101 nm)(3), respectively. In this part, successful applications of NEMO 3-D are demonstrated in the atomistic calculation of single-particle electronic states of the following realistically sized nanostructures: 1) self-assembled quantum dots (QDs) including long-range strain and piezoelectricity; 2) stacked quantum dot …

Strain-Engineered Self-Organized Inas/Gaas Quantum Dots For Long Wavelength (1.3Μm-1.5Μm) Optical Applications, Muhammad Usman, Dragica Vasileska, Gerhard Klimeck

Gerhard Klimeck

InAs/GaAs quantum dot systems can emit light at the wavelengths above 1.3μm by covering the InAs quantum dots with an InxGa1-xAs strain reducing capping layer (SRCL). The presence of the SRCL relaxes the strain in the growth direction while the in-plane compressive strain remains nearly unchanged. This results in an aspect ratio increase of the quantum dot. Both the strain relaxation in the growth direction and the aspect ratio change induce a non-linear red shift. This work studies the dependence of the emission wavelength on the thickness and the indium composition of the SRCL. Experimental topologies have been simulated and …

Multimillion Atom Simulations With Nemo 3-D, Shaikh Ahmed, Neerav Kharche, Rajib Rahman, Muhammad Usman, Sunhee Lee, Hoon Ryu, Hansang Bae, Steve Clark, Benjamin Haley, Maxim Naumov, Faisal Saied, Marek Korkusinski, Rick Kennel, Michael Mclennan, Timothy B. Boykin, Gerhard Klimeck

Gerhard Klimeck

The rapid progress in nanofabrication technologies has led to the development of novel devices and structures which could revolutionize many high technology industries. These devices demonstrate new capabilities and functionalities where the quantum nature of charge carriers plays an important role in determining the overall device properties and performance. For device sizes in the range of tens of nanometers, the atomistic granularity of constituent materials cannot be neglected: effects of atomistic strain, surface roughness, unintentional doping, the underlying crystal symmetries, or distortions of the crystal lattice can have a dramatic impact on the device operation and performance.

Quantum Confined Stark Shift And Ground State Optical Transition Rat In [100] Laterally Biased Inas/Gaas Quantum Dots, Muhammad Usman, Hoon Ryu, Sunhee Lee, Yui H. Tan, Gerhard Klimeck

Gerhard Klimeck

The atomistic tight binding simulator NEMO 3-D has previously been validated against the experimental data for quantum dots, wells, and wires in the InGaAlAs and SiGe material systems. Here, we demonstrate our new capability to compute optical matrix elements and transition strengths in tight binding. Systematic multi-million atom electronic structure calculations explore the quantum confined stark shift and the ground state optical transition rate for an electric field in the lateral [100] direction. The simulations treat the strain in a ~15 million atom system and the electronic structure in a subset of ~9 million atoms. The effects of the long …

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Josip Horvat

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Jianli Wang

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Stress/Strain Induced Flux Pinning In Highly Dense Mgb2 Bulks, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Chung-Kiak Poh, Jung Ho Kim, Josip Horvat, Dongqi Shi, Jianli Wang, Paul G. Munroe, X. F. Wang, Rongkun Zheng, S. P. Ringer, M Rindfleisch, Mike Tomsic

Shi Xue Dou

We have systematically studied the flux pinning behavior of MgB2 bulks synthesized by direct diffusion of Mg into pressed pellets of high purity crystalline B powder, with and without mixing with C and SiC nanoparticles, at a reaction temperature of 850degC for 10 hrs. All of the samples showed very high purity and high density, but their microstructure and flux pinning behavior showed significant differences. It was found that the pure MgB2 agrees with the deltaTc pinning model, nano-C doped MgB2 agrees with the deltal pinning model, while the SiC+MgB2 composite agrees with the deltaepsiv pinning model (stress/strain field pinning), …

Thermal-Strain-Induced Enhancement Of Electromagnetic Properties Of Sic-Mgb2 Composites, Rong Zeng, S X. Dou, Lin Lu, Wenxian Li, Jung Ho Kim, Paul G. Munroe, Rongkun Zheng, S P. Ringer

Shi Xue Dou

The effect of thermal strain caused by the different thermal expansion coefficients (α) of the MgB2 and SiC phases on the electromagnetic properties was studied for SiC–MgB2 composite, which was made by premixing SiC and B, followed by Mg diffusion and reaction. Thermal strain in the MgB2 phase was demonstrated with x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. In contrast to the common practice of improving the critical current density Jc and the upper critical field Hc2 of MgB2 through chemical substitution, by taking advantage of residual thermal strains, we are able to design a composite showing only a …

Strain Modulated Magnetization And Colossal Resistivity Of Epitaxial La2/3ca1/3mno3 Film On Batio3 Substrate, Zhenxiang Cheng, Xiaolin Wang, S. X. Dou, M Osada, Hideo Kimura

Shi Xue Dou

A sharp drop in resistance and a magnetization anomaly have been observed in La2/3Ca1/3MnO3 film in zero magnetic field at the BaTiO3 substrate structural phase transition temperature, due to the substrate clamping/strain effect, which is confirmed by Raman scattering. However, the anomalies for both resistance and magnetization were eliminated by a strong external magnetic field. These phenomena indicate that strain can cause colossal resistance and a change in magnetization which resembles the magnetic field effect. The interplay of the external forces (strain and magnetic field) is a good demonstration of the strong coupling between spin and lattice in colossal magnetoresistance …

Poly(3-Methylthiophene) Electrochemical Actuators Showing Increased Strain And Work Per Cycle At Higher Operating Stresses, Van-Tan Truong, Philip G. Whitten, Jie Ding, Binbin Xi, Geoffrey M. Spinks, G G. Wallace

Gordon Wallace

Conducting polymers, such as polythiophenes, are promising low voltage actuator materials. The performance of these materials has improved significantly in recent years. A remaining problem, however, is the significant decline in the actuation strain produced when the external stress is increased. Using a poly(3-methylthiophene) actuator in an ionic liquid electrolyte it is shown that the isotonic actuation actually increases with increasing applied stress. The work output per cycle consequently increases at higher stresses, which is very desirable for practical devices. Although theoretically predicted, these results are the first demonstration of the increased actuator performance at higher operating stresses. The actuation …

Signal Processing Methods Implemented In A Novel Fbg Sensing System For Vibration/Dynamic Strain Measurement, Xingyuan Xu, Enbang Li, Jiangtao Xi, Joe F. Chicharo

Professor Joe F. Chicharo

We have demonstrated a novel Fiber Bragg Grating sensing system based on a Fabry-Perot tunable filter for measuring dynamic processes. This system is very suitable for multipoint vibration or dynamic strain detection. However, in some conditions, the response time of Fabry-Perot tunable filter will influence the sensitivity of the sensor that the sensitivity is not kept constant. Therefore, post-processing for the measured vibration signal is necessary to solve this problem. In this paper, the demodulation technique of this system is briefly described and two signal processing methods are introduced to deal with the measured signal to obtain stable measurement of …

Development Of A Compression Test Device For Investigating Interaction Between Diffusion Of Biodiesel And Large Deformation In Rubber

A.S. Md Abdul Haseeb

Motivated by environmental and economic factors, biodiesel has been introduced to partially replace the diminishing stock of petroleum-based fuel. However, the use of biodiesel such as palm biodiesel is placing additional demands on automotive components, e.g. rubber components, due to a compatibility issue in the fuel system. In engineering applications where hostile environments are involved, the long-term mechanical response of rubber components is affected by interactions existed between diffusion of liquids into the material and fluctuating multiaxial loading. Hence, it is crucial to investigate the durability of rubber components in this aggressive environment. A number of studies on static immersion …

A Time-Efficient Method For Analyzing Bone Strain With Large Subject Pools, Daniel Leib, Eric Dugan, Henry Wang

Daniel Leib

No abstract provided.

Optimization For High-Level Expression In Pichia Pastoris And Purification Of Truncated And Full Length Recombinant Sag2 Of Toxoplasma Gondii For Diagnostic Use, Init Ithoi

Init Ithoi

SAG2 is one of the major surface antigens of the intracellular protozoan parasite Toxoplasma gondii. In the present study, truncated recombinant SAG2(S) and full length recombinant SAG2(T) of T. gondii were optimally produced (similar to 15 mg/liter) in Pichia pus tons expression system using BMMY medium at pH 3, 25 degrees C in 0.5-1% methanol and a time-course of 1-2 days. The recombinant proteins were purified using a commercial gel filtration purification system obtaining similar to 33% recovery. The purified SAG2(S) and SAG2(T) showed molecular masses of 45 and 36 kDa by SDS-PAGE, respectively. The recombinant proteins were evaluated by …

Growth Stress In Eucalyptus Dunnii, Timothy N. Murphy, Michael Henson, Jerome K. Vanclay

Professor Jerome K Vanclay

Growth stress in 9-y-old plantation-grown Eucalyptus dunnii was assessed by measuring longitudinal growth strain. Strain varied considerably (370–1560 ìm–1) and was sufficiently heritable (h2 =0.3–0.5) that tree breeding may be an effective way to reduce the incidence of growth stress in this species. Although the formation of longitudinal growth strain appears to be under strong genetic control (P = 0.0015), there was a tendency for tall thin trees to exhibit higher stress than short thick trees (P = 0.025 for height:diameter ratio). Two provenances and three families identified in this study show potential as superior material for further tree breeding.

An Integrated Modeling Method For Bone Strain Analysis, Daniel Leib, Henry Wang, Eric Dugan

Daniel Leib

No abstract provided.

An Integrated Modeling Method For Tibia Strain Analysis, Daniel Leib, Henry Wang

Daniel Leib

No abstract provided.

Aftercare When There Is No Aftercare: Policy Solution And Evaluation Plan Proposal, Sharlette A. Kellum Ph.D.

Dr. Sharlette A. Kellum-Gilbert

Juvenile justice systems that release offenders without court-ordered supervision are not addressing the needs of parents as guardians over young law breakers. Help for parents needs to come from the professional community, the neighborhood, the school system, and the juvenile justice system. Hence, this paper proposes that a group of volunteers from these entities be assembled into a pilot program with the goal of reducing juvenile recidivism, relapse, and reincarceration. This program will aim to guide juvenile offenders into successful reintegration into the community and prevent reincarceration/relapse of youths released from juvenile corrections facilities with no court-ordered supervision. A developmental …

Fretting Wear Of Metallic Multilayer Films

A.S. Md Abdul Haseeb

Fretting wear behaviour of electrodeposited Cu/Ni multilayer films with 10 and 5 nm thick sublayers has been investigated against a hardened steel ball as the counter body and compared with that of the constituents, Cu and Ni. The wear tests were carried out by using a ball-on-flat geometry at a translation frequency of 8 Hz and slip amplitude of 100 μm. Friction force was recorded on line during the tests. At the end of the tests, the wear scars were examined by laser surface profilometry, scanning electron microscopy and energy dispersive X-ray microanalysis. It has been observed that the frictional …