bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study on the Performance of Rolling Oil During Cold Rolling of Stainless Steel Simulating Industrial Condition
Authors: Mahapatra R. , Singh Rait Jaspal , Pappy Samuel , Singh Inder , Kumar Ajay , Saxena Deepak , Martin V. , Malhotra R. K.
Published: July 2013

The primary role of rolling oil in cold rolling is to reduce friction at the rubbing interface of the work roll and metal sheet surface. The rolling performance as well as cost effectiveness of rolled products is influenced by quality of the rolling oil. Lubricants are required to function under increasingly stressful operating conditions, so it is a challenge to evaluate the product under simulated conditions to improve the customer confidence in its performance.

A steel rolling mill customer had requested us to develop a rolling oil to roll stainless steel in a new 3-stand 18-high rolling mill and demonstrate its performance on an experimental set up. The present paper describes the methodology adopted to assess the suitability of a rolling oil for the particular rolling mill. The screening was carried out with a SRV (Schwingungs Reibungs und Verschleisstest, meaning Vibration, friction and Abrasion) tribometer and EHD (Elasto-hydrodynamic) interferometry based film thickness apparatus to assess the frictional and film forming characteristics of the oil under simulated operating conditions. In addition, simulated tests were carried out on a laboratory 2-Hi Experimental rolling mill to find out the specific roll force (rolling force per unit width of the strip being rolled) required to obtain 55–60% cumulative reduction in three passes as desired by the customer for different grades of stainless steel. Based on results obtained in the laboratory mill simulating industrial test conditions, the product was recommended and was accepted by the customer for use in their rolling mill.
Analysis of Voxel Size During Two-Photon Polymerization
Authors: Gregory Serge L. H. F. , Kannatey-Asibu Elijah
Published: July 2013

Two-photon polymerization combines the concepts of multi-photon absorption with polymerization of a free radical polymerizable monomer. It can be used to fabricate a variety of micro-devices including micro-fluidic, biomedical, micro-optical, and micro-mechanical devices. A critical aspect of two-photon polymerization is the resolution of the process. This paper derives an expression for the voxel (volume element) size produced during two-photon polymerization. The model assumes a Gaussian beam and the effects of beam power, lens parameters, and resin polymerization threshold are investigated. A sensitivity analysis is also performed, and the results show that the voxel formed is more sensitive to changes in beam power and resin threshold than to changes in the incident beam diameter.
Laser Shock Induced Nano-Patterning of Graphene
Authors: Li Ji , Cheng Gary J. , Zhang Rongjun , Jiang Hanqing
Published: July 2013

Nano-patterning of graphene film by a novel approach making use of laser ablation generated pressure is presented in this paper. Arrays of nanoscale holes were fabricated by applying laser shock pressure on graphene film suspending on well trenches in silicon substrate. Round holes with diameters ranging from 50 to 200 nm on graphene film were successfully punched. The critical pressure was found to be dependent on the diameter of holes. Smaller the diameters, higher critical pressure, which was also captured by the molecular dynamic (MD) simulations. The laser shock based approach presented in this paper provides an effective way to pattern graphene film with nanoscale features at an easy, fast and scalable manner.
Nanoparticles Embedding Into Metallic Materials by Laser Direct Irradiation
Authors: Lin Dong , Suslov Sergey , Ye Chang , Liao Yiliang , Liu C. Richard , Cheng Gary J.
Published: July 2013

We report a method to half-embed nanoparticles into metallic materials. Transparent and opaque nanoparticle (laser wavelength 1064 nm) were both successfully half-embedded (partial part of nanoparticles embedded into matrix while other parts still stay above the matrix) into metallic materials. Nanoparticles were coated on sample surface by dip coating before laser irradiation. After laser irradiation of different pulses and laser fluencies, nanoparticles were embedded into metal. The mechanism and process of embedding were investigated.
Deposition of Al-Doped Zinc Oxide by Direct Pulsed Laser Recrystallization at Room Temperature on Various Substrates for Solar Cell Applications
Authors: Zhang Martin Y. , Nian Qiong , Cheng Gary J.
Published: July 2013

In this study, a method combining room temperature pulsed laser deposition (PLD) and direct pulsed laser recrystallization (DPLR) are introduced to deposit superior transparent conductive oxide (TCO) layer on low melting point flexible substrates. As an indispensable component of thin film solar cell, TCO layer with a higher quality will improve the overall performance of solar cells. Alumina-doped zinc oxide (AZO), as one of the most promising TCO candidates, has now been widely used in solar cells. However, to achieve optimal electrical and optical properties of AZO on low melting point flexible substrate is challenging. Recently developed direct pulsed laser recrystallization (DPLR) technique is a scalable, economic and fast process for point defects elimination and recrystallization at room temperature. It features selective processing by only heating up the TCO thin film and preserve the underlying substrate at low temperature. In this study, 250 nm AZO thin film is pre-deposited by pulsed laser deposition (PLD) on flexible and rigid substrates. Then DPLR is introduced to achieve a uniform TCO layer on low melting point flexible substrates, i.e. commercialized Kapton polyimide film and micron-thick Al-foil. Both finite element analysis (FEA) simulation and designed experiments are carried out to demonstrate that DPLR is promising in manufacturing high quality AZO layers without any damage to the underlying flexible substrates. Under appropriate experiment conditions, such as 248 nm in laser wavelength, 25 ns in laser pulse duration, 15 laser pulses at laser fluence of 25 mJ/cm2, desired temperature would result in the AZO thin film and activate the grain growth and recrystallization. Besides laser conditions, the thermal conductivity and crystallinity of the substrate serve as additional factors in the DPLR process. It is found that the substrate’s thermal conductivity correlates positively with the AZO crystal size; the substrate’s crystallinity correlates positively with the AZO film’s crystallinity. The thermal expansion of substrate would also contribute to the film tensile stress after processed by DPLR technique. The overall results indicate that DPLR technique is useful and scalable for flexible solar cell manufacturing.
Performance Analysis and Optimization of Remanufacturing Systems With Stochastic Returns
Authors: Xiao Guoxian , Jin Xiaoning , Chang Qing , Biller Stephan , Ni Jun , Hu S. Jack
Published: July 2013

This paper considers a modular product assembly and inventory planning and control problem in a remanufacturing environment. The return process of end-of-life product is a stochastic process in terms of arriving time, quality and quantity. We investigate the returned module reassembly policies in an assemble-to-order strategy. A threshold policy is considered to control the admission of the product returns and its effect on the trade-off between excessive inventory and stock out. We study how the control parameters in these strategies relate to the average inventory level and stock out level of the remanufacturable modules. Starting with a single quality grade problem, we extend the analysis to a multiple quality grade problem and derive exact expression of the system performance measures as function of the control parameters. Main objective of this paper is to provide managerial insights into decision-making for stochastic remanufacturing systems.
End Milling Force Model Calibration Using Measured Force Profiles
Authors: Zhao Yong , Jerard Robert B. , Fussell Barry K.
Published: July 2013

This paper introduces a method to use the cutting force profile, measured from a Kistler dynamometer, to calibrate a mechanistic based force model containing four cutting coefficients. The undesirable effects of tool vibration and force sensor dynamics are minimized by carefully choosing experimental conditions. Cutting force profiles provide an array of force versus chip thickness based values that can be used in a regression fit to find the model coefficients. Results show that different ranges of chip thickness used in the calibration process result in slightly different cutting coefficients, which implies chip thickness has an effect on cutting coefficients. The force profile based cutting coefficients are then used in the cutting force model to estimate the peak resultant cutting force. Comparison of model estimates and measured values show less than 10% error.
PneuViz: MTConnect Compliant Compressed Air Monitoring Application
Authors: Atluru Sri , Deshpande Amit , Huang Sam , Pieper Ron
Published: July 2013

Compressed air is regarded as the fourth largest utility in the manufacturing industry behind electricity, natural gas and water. It is used in a wide variety of pneumatic, mechanical and maintenance applications in every manufacturing facility. However, very little efforts have been made in trying to monitor and optimize the utilization of compressed air. Hence, a project was conducted to study and analyze the utilization of compressed air under various scenarios that are typical during metal cutting operation in a manufacturing facility.

PneuViz application was developed using LabVIEW programming package to monitor and analyze the results. PneuViz was seamlessly linked with the MTConnect data being broadcasted on the corporate network. PneuViz provides drill down capability to analyze cost of compressed air on a per part, per machine, and per customer order. Monitoring the utilization of compressed air by a stand-alone Computer Numerical Control (CNC) machine as well as the overall utilization on the shop floor was facilitated by the use of a sensor system comprising of a flow meter, Data Acquisition Device (DAQ), and a power sensor (load meter). MTConnect was used to enable plug-and-play functionality across the various machines on the shop floor. This was implemented by developing a system of MTConnect adapters that were able to capture the raw sensor data and broadcast it over the Ethernet network.

Subsequently, analysis was carried out over various scenarios to determine the cost, energy and carbon footprint impact of the compressed air usage on the manufacturing shop floor.
An Integrated Design Strategy for Dust Collection and Slurry Transport Systems and Implementation in a Steel Plant
Authors: Peters Daniel J. , Young Aquelius A.
Published: July 2013

Dust collection and slurry transportation systems are essential for effective collection and removal of metallic and dust fines. These are mainly used to eliminate pollution, recover water that is reused in the core steel process, and to capture solids which can be used in the raw material processes of making reduced iron. However, maintenance of slurry transportation systems is not only complex but also expensive, if not designed properly. This paper presents an integrated slurry transportation design strategy for greater performance, less maintenance and increased reliability thus resulting in effective asset management. This design has been implemented and successfully tested in an existing Steel plant. Experience suggests that the asset management is not merely a maintenance activity however methodical it may be. Although periodical maintenance cannot be totally eliminated, specifically in cases with slurry transport systems, the suggested approach in this paper uses a thoughtful design strategy with emphasis on safeguarding the environment, simplified routine maintenance and efficient system operation.
Nanotwins in Copper Nanowires Controlled by Laser Assisted Electrochemical Deposition
Authors: Liu Zhikun , Liao Yiliang , Cheng Gary J. , Wang Yuefeng
Published: July 2013

Nanotwins in metallic nanowires can improve mechanical strength and maintain high electrical conductivity. We demonstrated a method of pulse laser assisted electrodeposition, which can generate dense nanotwins with different directions in copper nanowires of uniform length. Transmission electron microcopy characterization shows at lower electrochemical potential of −0.2 Volt, nanotwins tend to align along the longitudinal direction of the nanowires whereas at the high potential −0.8 Volt, nanotwins of {111}/<112> type that cross the width of the wire are formed. We investigated the two types of nanotwins by comparing the microstructures under different electrochemistry and laser setting. Two different mechanisms are proposed for two kinds of nanotwin — annealing twins and growth twins.
Nanodiamond Reinforced PLLA Nanocomposites for Bone Tissue Engineering
Authors: Zhang Qingwei , Gogotsi Yury , Lelkes Peter I. , Zhou Jack G.
Published: July 2013

Nanodiamond (ND) is an attractive nanomaterial for reinforcement of biopolymers due to the ND’s superior mechanical and chemical properties, and low biotoxicity. A novel composite material has been produced for bone scaffolds utilizing the biodegradable polymer poly(L-lactic acid) (PLLA) and octadecylamine-functionalized nanodiamond (ND-ODA). Composites were prepared by admixing to a PLLA/chloroform solution chloroform suspension of ND-ODA in concentration range of 0–10% (w/w). The dispersion of ND-ODA evaluated by transmission electron microscopy (TEM) shows uniform distribution of ND-ODA in PLLA matrix. The composites were characterized by differential scanning calorimetry (DSC). DSC analysis of the composites showed no significant thermal behavior changes with the addition of ND-ODA into the polymer. Biomineralization test shows that ND-ODA can enhance the mineral deposition on scaffolds. Improved mechanical properties and good biocompatibility with enhanced biomineralization combined suggest that ND-ODA/PLLA might have potential applications for bone tissue engineering.
Micro Characterization of Mg and Mg Alloy for Biodegradable Orthopedic Implants Application
Authors: Gong Haibo , Kontsos Antonios , Kim Yoontae , Lelkes Peter I. , Zhang Qingwei , Yao Donggang , Hazeli Kavan , Zhou Jack G.
Published: July 2013

Magnesium as a candidate metallic biomaterial for biodegradable orthopedic implants was evaluated in-vitro in terms of degradation behavior, biocompatibility and mechanical property both in macro- and micro-scale. Micro structure of pure Mg and AZ61 after degradation in both simulated body fluid (SBF) and cell culture environment were analyzed. Different from AZ61, pure Mg degraded at a higher rate and attracted large amount of salt precipitation which formed a layer covering the surface. Much less pitting degradation and salt deposition were observed on both pure Mg and AZ61 in cell culture environment compared to in SBF. After culturing for 7 days, EAhy926 cells growing on AZ61 showed significant higher proliferation rate as of cells growing on pure Mg. Higher proliferation rates indicated that cells grew better on slow-degrading AZ61 than on fast-degrading pure Mg. Cells growing on AZ61 proliferated much better and assembled together to form a consistent tissue-like micro-structure, while cells spread and reached out on the surface of pure Mg, possibly due to low cell density and lack of cellular communication. The elastic modulus and tensile yield strength of magnesium are closer to those of natural bone than other commonly used metallic biomaterials. It was shown that Mg was biodegradable, biocompatible and had appropriate mechanical strength, thus Mg and its alloys showed great potential for deployment in a new generation of biodegradable orthopedic implants.
Study of Pressure Distribution in Compliant Coated Abrasive Tools for Robotic Polishing
Authors: Umer Muhammed , Saptaji Kushendarsyah , Subbiah Sathyan
Published: July 2013

Robotic polishing applications involve the use of coated abrasive tools along with a compliant backing pad. The compliance helps in conforming to curved surfaces and also in blending with unpolished areas. This compliance and its effect are currently controlled only by empirical choice of various backing pad designs and materials. A better understanding of this important characteristic of these tools will lead to better process control. One of the effects of the compliance or stiffness of the backing pad under a certain applied load (robotic force control) is on the contact area and pressure distribution applied on the abrasive grains in that area. This pressure distribution in turn dictates how material is removed in the area of contact. Here, we report preliminary results of the pressure distribution exerted by an abrasive tool mounted on a robot using pressure film sensors and compare results with a simple finite element model.
In-Situ Characterization of MWCNTs Reinforced Epoxy Nanocomposite Under Mechanical Load
Authors: Wang Xinnan , Cui Peng , Tangpong X. W.
Published: July 2013

In this study, the mechanical properties of multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposite were measured with the custom-built micro/nano three point bending tester mounted on an atomic force microscope (AFM). With in-situ observation of the AFM, the movement of an individual MWCNT on the sample surface was traced, captured, and quantified using the image correlation technique. The Halpin-Tsai and Hui-shia models were applied and compared with the experimental data. Results showed that the elastic modulus from the experiment is much lower than the predicted values from the two models. Detailed mechanical deformation behavior and MWCNT reinforcement mechanism were discussed.
Estimating the Cohesive Zone Model Parameters for Carbon Nanotube–Polymer Interface Using Inverse Finite Element Approach
Authors: Jiang Lingyun , Nath Chandra , Samuel Johnson , Kapoor Shiv G.
Published: July 2013

During machining of carbon nanotube (CNT)-polymer composites, the failure of the polymer elements occurs at the CNT-polymer interface. The interfacial behavior that can be represented by a cohesive zone model (CZM) is mainly influenced by two parameters, viz., interfacial strength and fracture energy. The objective of this study is to estimate these two specific CZM parameters using an inverse finite element (FE) simulation approach that works based on an iterative error minimization procedure. Nanoindentation tests have been conducted on a CNT-polyvinyl alcohol (PVA) composite sample containing 4 wt% multi-walled nanotubes (MWNTs). A 2D axisymmetric FE model of nanoindentation has been developed. This micro-structure based model considers the CNT, the PVA, and the cohesive zone of interface as three individual phases. The unknown interfacial parameters are determined by minimizing the error between the simulation load-displacement curve and the experimental results. The interfacial strength and the fracture energy at the CNT-PVA interface are estimated to be approximately 40 MPa and 16e−3 J/m2, respectively. This approach provides a convenient framework to understand the role of the CZM parameters at the interface between the CNT and polymer matrix.
M–K Analysis of Forming Limit Diagram Under Stretch-Bending
Authors: He Ji , Xia Z. Cedric , Li Shuhui , Zeng Danielle
Published: July 2013

Since the Forming limit diagram (FLD) was introduced and developed by Keeler etc. about four decades ago, it has been intensively studied by researchers and engineers. Most work has been focused on the in-plane deformation which is considered as the dominant mode of the most forming processes. However the effect of out-of-plane deformation modes especially bending effect becomes important in accurate prediction of formability when thick sheet metal and smaller forming radii are encountered. Recent work on experiment research of stretch-bending induced FLD (BFLD) shows that it gives higher formability than conventional forming limit. In this paper, bending effect through the sheet metal thickness on right-hand side of FLD is studied. The Marciniak-Kuczynski (M-K) analysis is extended to include bending and models based on both flow theory and deformation theory are proposed. The radial return method is adopted as the frame to calculate the stress states from given strain and deformation history. The effect of bending and unbending process on the Right-Hand-Side FLD is investigated and compared. The obtained results show that the bending process slightly decreases the sheet metal formability on right-hand side in flow theory based model which is a discrepancy with the prediction of deformation theory based BFLD model. The insight gained from new proposed FLD prediction model in this paper provides an understanding of how the bending process effects on the FLD. This is important for the further research to reconsider the problems of how the bending effect evolves in forming process to enhance the conventional FLD and how to get a perfectly true theoretical explanation for this phenomenon.
A Microlens Array on Curved Substrates by 3D Micro Projection and Reflow Process
Authors: Zhang Hao , Li Lei , McCray David L. , Yao Donggang , Yi Allen Y.
Published: July 2013

Microlens arrays are becoming increasingly important because of their widespread applications in optical, electronic, and energy fields. Currently, microlens array fabrication processes are mainly developed on planar substrates. For nonplanar substrates, existing fabrication methods suffer from various disadvantages. This is largely due to the inherent technical complexity of 3D microstructure fabrication processes. In this work, an innovative 3D fabrication method for microlens arrays on curved surfaces is introduced. To fabricate the microlens array, a PMMA microlens array on a curved surface was used as the projection microlens array. A thick layer of positive tone photoresist SPR 220 was spin coated on a curved, titanium-coated aluminum substrate. A pre-designed pattern was projected onto the photoresist by using a home built exposure system. The development process resulted in micro cylinders on the curved substrate. A thermal reflow process was then performed on the cylinder array, forming a microlens array. Experiments were conducted to evaluate the factors that affect the shapes of the microlenses. These factors include film thickness variation, exposure and development variation, slope of the substrate, height to width ratio and heating time in thermal reflow process. Finally microlenses were tested by using a Twyman-Green interferometer.
A Note on High Aspect-Ratio SU-8 Micromechanical Structures Using Mask-Less Direct Laser Writing
Authors: Ghosh Siddharth , Ananthasuresh G. K.
Published: July 2013

We report high aspect-ratio micromechanical structures made of SU-8 polymer, which is a negative photoresist. Mask-less direct writing with 405 nm laser is used to pattern spin-cast SU-8 films of thickness of more than 600 um. As compared with X-ray lithography, which helps pattern material to give aspect ratios of 1:50 or higher, laser writing is a less expensive and more accessible alternative. In this work, aspect ratios up to 1:30 were obtained on narrow pillars and cantilever structures. Deep vertical patterning was achieved in multiple exposures of the surface with varying dosages given at periodic intervals of sufficient duration. It was found that a time lag between successive exposures at the same location helps the material recover from the transient changes that occur during exposure to the laser. This gives vertical sidewalls to the resulting structures. The time-lags and dosages were determined by conducting several trials. The micromechanical structures obtained with laser writing are compared with those obtained with traditional UV lithography as well as e-beam lithography. Laser writing gives not only high aspect ratios but also narrow gaps whereas e-beam can only give narrow gaps over very small depths. Unlike traditional UV lithography, laser writing does not need a mask. Furthermore, there is no adjustment for varying the dosage in traditional UV lithography. A drawback of this method compared to UV lithography is that the writing time increases. Some test structures as well as a compliant microgripper are fabricated.
A New Concept in Design of Rheolytic Thrombectomy Devices: The Coanda Effect
Authors: Chung Cheng-Shiu , Cornejo Sergio L. , Huo Ming , Finol Ender A.
Published: July 2013

The Coanda effect, which was first named by Henri Coanda in 1910, is the phenomenon when a fluid, gas or liquid, attaches to a solid surface, called the Coanda surface. The direction of this adhered flow changes along with the surface because of the Van der Walls forces or surface tension. Therefore, the pressure distribution of the ambient fluid is also altered due to the bent attached Coanda flow. The fluid material properties, Coanda flow velocity, curvature of the Coanda surface, velocity of the ambient fluid flow, and distance to the wall above the Coanda flow are the primary factors affecting this pressure distribution. In experimental studies, Panitz and Wasan [1] evaluated the pressure distribution of the Coanda effect by using pressure sensors on the Coanda surface and a colored dye solution in the flow. By means of photographs and experimental data, they describe the influence of different heights of the shroud (a sheath plate above the Coanda surface) and the secondary flow entrainment (flow of ambient fluid) on the pressure profiles. Vortices occur beneath the Coanda flow when the height of the shroud is lower than a specified reference. Cutbill et al. [2] developed a high speed Coanda flow k-ε turbulence model in the application of PHOENICS to improve the prediction of the mixing rate, shock wave structure and flow separation. The pressure drop occurs near the Coanda surface in both experimental and computational prediction results.
Theory of Growth and Rupture of Abdominal Aortic Aneurysm
Authors: Volokh Konstantin Y. , Vorp David A.
Published: July 2013

We present here a coupled mathematical model of growth and failure of the abdominal aortic aneurysm (AAA). The failure portion of the model is based on the constitutive theory of softening hyperelasticity where the classical hyperelastic law is enhanced with a new constant indicating the maximum energy that an infinitesimal material volume can accumulate without failure. The new constant controls material failure and it can be interpreted as the average energy of molecular bonds from the microstructural standpoint. The constitutive model is compared to the data from uniaxial tension tests providing an excellent fit to the experiment. The AAA failure model is coupled with a phenomenological theory of soft tissue growth. The unified theory includes both momentum and mass balance laws coupled with the help of the constitutive equations. The microstructural alterations in the production of elastin and remodeling of collagen are reflected in the changing macroscopic parameters characterizing tissue stiffness, strength and density. The coupled theory is used to simulate growth and rupture of an idealized spherical AAA. The results of the simulation showing possible AAA ruptures in growth are reasonable qualitatively while the quantitative calibration of the model will require further clinical observations and in-vitro tests. The presented model is the first where growth and rupture are coupled.
Strength Retention of a New Microbial Cellulose Scaffold and Existing Collagen-Based Scaffolds After In Vivo Implantation in a Rabbit Model
Authors: Dishowitz Michael I. , Zgonis Miltiadis H. , Harris Jeremy J. , Ace Constance , Soslowsky Louis J.
Published: July 2013

Rotator cuff tendon tears often require large tensions for repair [1] and these tensions are associated with poor outcomes including rerupture [2]. To address this, repairs are often augmented with collagen-based scaffolds. Microbial cellulose, produced by A. xylinum as a laminar non-woven matrix, is another candidate for repair augmentation [3]. An ideal augmentation scaffold would shield the repair site from damaging loads as they change throughout the healing process. Although the initial mechanical properties of clinically used scaffolds have been well characterized [4–6], their mechanical behavior following implantation is not known. As a result, the role of these scaffolds throughout the healing process remains unknown. Therefore, the objective of this study is to characterize the mechanical behavior of existing collagen-based scaffolds and a new, microbial cellulose scaffold over time using an in vivo model. We hypothesize that: 1) collagen-based scaffolds will show decreased stiffness (1a) and suture pullout loads (1b) over time when compared to initial values while the microbial cellulose scaffold will not; and 2) the collagen-based scaffolds will have decreased stiffness (2a) and suture pullout loads (2b) when compared to the new, microbial cellulose scaffold at all timepoints.
Simultaneous In Vitro Measurement of Intervertebral Disc Bulging and Pressure
Authors: Gohgi Satoshi , Takigawa Tomoyuki , Kamal Ranjith , Espinoza Orías Alejandro A. , An Howard S. , Andersson Gunnar B. J. , Inoue Nozomu
Published: July 2013

Disc herniation and low back pain constitute widespread problems in modern society, although a direct relationship between both conditions has not been established. Proper quantification of intervertebral disc bulging is important for studies on pathogenesis and pathological conditions of disc related disease such as herniations. Intervertebral disc disorders are related to the mechanical failure of the annulus fibrosus [1] and annulus failure is caused by high tensile stresses produced by the high intervertebral disc pressure [2]. To the best of the authors’ knowledge, there has been no study on the simultaneous measurement of disc bulging and the disc pressure under physiological loading conditions. The objective of this study was to describe the radial displacement of the outer annulus wall under a variety of loading schemes. Moreover, this data could also be used to assist in the validation process for finite element models.
Computer Simulations of the Blood Flows and the Growth of Stenosis in Arteries With Bends and Bifurcations
Authors: Liu Biyue , Tang Dalin
Published: July 2013

Heart attack and stroke are the chief and the 3rd largest causes of death in the United States, respectively. A heart attack occurs when the blood supply to an area of heart muscle is blocked, usually by a clot in a coronary artery; a stroke occurs when the blood supply to a region of the brain is lost. The most frequent cause of loss of blood supply to brain tissue or to heart muscle is atherosclerosis, which involves complex interactions between the artery wall and the blood flow. Caro et al first suggested that the distribution of fatty streaking in human aorta may be coincident with regions in which the shear rate at the arterial wall is locally reduced [1]. After that, intensive research has been conducted to statistically study the role of shear stress in atherosclerosis and to quantitatively determine the correlation between the low shear stress and the development of atherosclerotic plaques [2–8]. It is widely believed that fluid shear stress acting on the artery wall plays an important role in the pathogenesis of atherosclerosis. The objectives of this project are to investigate how the geometrical adaptation of atherosclerotic plaques is related to the wall shear stress (WSS) and to study the influences of the flow parameters on the growth of the atherosclerotic plaque using computational models.
Tailoring the Crosslinking and Degradation of Hyaluronic Acid Hydrogels to Enhance Neocartilage Formation by Mesenchymal Stem Cells
Authors: Chung Cindy , Beecham Michael , Mauck Robert L. , Burdick Jason A.
Published: July 2013

Optimization of tissue formation is essential for the success of a tissue engineered scaffold. Crosslinking density affects encapsulated cell viability, initial mechanical properties, and the diffusion of nutrients and waste. Degradation affects scaffold properties, cell-scaffold interactions, and the quantity and distribution of extracellular matrix (ECM) produced by entrapped cells with time [1,2]. Previously, we showed that neocartilage formation by encapsulated chondrocytes is influenced by network structure and properties [3], and that the chemistry of hyaluronic acid (HA) hydrogels supports and promotes the chondrogenic differentiation of mesenchymal stem cells (MSCs) [4]. While others have also investigated the use of HA-based hydrogels for cartilage repair [5,6], by tuning HA network degradation, with the inclusion of hydrolytically degradable components, we show the effects of temporal network structure on scaffold properties and enhanced neocartilage formation. This type of control could help translate tissue engineering technology to clinical applications.
DT-MRI Based Numerical Simulation of Collagen Fiber Deformation in Human Articular Cartilage
Authors: Pierce David M. , Trobin Werner , Trattnig Siegfried , Bischof Horst , Holzapfel Gerhard A.
Published: July 2013

Within the articular cartilage (composed of fluid, electrolytes, chondrocytes, collagen fibers, proteoglycans and other glycoproteins) fibers of predominantly Type II collagen provide tensile strength and stiffness to the solid phase, a proteoglycan gel. Collagen fibers exhibit a high level of structural organization usually consisting of three sub-tissue zones: (i) a superficial tangent zone with fibers which are tangential to the articular surface, (ii) a middle zone with fibers isotropically oriented, (iii) a deep zone with fibers oriented perpendicular to the subchondral bone [1]. Given the importance of this collagen fiber fabric in the mechanical properties of articular cartilage, many destructive and nondestructive experimental methods have been pursued to characterize fiber orientation and density.
Effect of Dose, Timing and Delivery of Tumor Necrosis Factor Alpha as a Cryoadjuvant in Cryosurgery of ELT-3 Uterine Leiomyoma (Fibroid) Tumor
Authors: Jiang Jing , Bischof John
Published: July 2013

Uterine leiomyoma (fibroid) is the most common indication for hysterectomy in premenopausal women. Cryomyolysis is a uterus sparing procedure in which a myoma is frozen by a cryoprobe, and that causes tissue necrosis upon thawing of the frozen tissue and eventual reduction in myoma size. Cryomyolysis allows both the placement of the minimally invasive cryoprobe and the ensuing iceball growth to be controlled under image guidance (ultrasound - US or magnetic resonance - MR) [1, 2]. Unfortunately, although the iceball is readily visualized, the tissue at the periphery of the iceball is not completely destroyed. This not only potentiates the later recurrence of the myoma, but also limits the predictability of the procedure by imaging techniques. Clearly, techniques that can improve the correspondence between the imaged iceball and the destroyed tissue will improve cryomyolysis and other cryosurgical procedures.
Stress Evaluation of a Short, Medium and Long Stem Proximal Fill Femoral Implants
Authors: Arno Sally , Kinariwala Neal , Takemoto Richelle , Hennessy Daniel , Nguyen Nguyen Q. , Chan Keith , Fetto Joseph , Walker Peter S.
Published: July 2013

The femoral stem of a traditional total hip arthroplasty is believed to be essential for fixation and stability. Stems achieve early stability in a non-physiological fashion by a combination of friction and circumferential displacement of bone, similar to that of a nail being impacted into a piece of wood. In contrast, the “Revelation” femoral prosthesis, produced by DJO Surgical Corporation, relies upon a proximal lateral expansion (“Lateral Flare” design concept) to achieve stability.
A Stochastic Field/Agent Model of Angiogenesis
Authors: Das Anusuya , Asada Harry , Lauffenburger Doug , Kamm Roger
Published: July 2013

Angiogenesis is the formation of blood vessels from an existing vessel or a monolayer of endothelial cells. It is crucial during the processes of tissue and organ maintenance, wound healing, and development and also plays a crucial role in tumor growth. An understanding of this process is also critical from a tissue engineering perspective. Several biochemical factors such as VEGF, Angiopoietin I (Ang I), Angiopoietin II (Ang II), PLGF, PDGF, TNF α, TGF β, α-FGF, β-FGF, ENA/VASP [1] and biomechanical factors such as extracellular matrix (ECM) stiffness, interstitial flow, shear stress affect the formation of capillaries. While some of them are proangiogenic, others are anti-angiogenic. A balance in these factors is decisive to the characteristics of the capillaries formed.
Posterolateral Chest Deformations From Seat-Mounted Side Airbag Deployments
Authors: Hallman Jason J. , Yoganandan Narayan , Pintar Frank A.
Published: July 2013

Since the introduction of torso-protecting side airbags (SAB) in the middle of the previous decade, their prevalence has increased at a considerable rate. By model year 2008, torso SAB availability increased to 65% of new vehicles sold in the United States [1]. This increasing popularity has necessitated a scientific understanding of injury risks associated with SAB deployment. Although much has been reported regarding detrimental frontal airbag deployment [2], detrimental SAB deployment scenarios remain obscure.
Mechanics of Deformation-Induced Degradation of Poly(L-Lactic Acid) Endovascular Stents
Authors: Soares João S. , Moore James E. , Rajagopal Kumbakonam R.
Published: July 2013

Fully biodegradable polymeric stents are thought to be the third revolution in minimally invasive cardiology. After the breakthrough development of percutaneous balloon angioplasty and the dawn of the drug eluting stents era, increasing interest is being brought to the concept of temporary implants that fulfill the mission and step away.
Modular Control of Human Walking: A Modeling and Simulation Study
Authors: Neptune Richard R. , Clark David J. , Kautz Steven A.
Published: July 2013

Recent evidence suggests that performance of complex locomotor tasks such as walking may be accomplished using a simple underlying organization of co-active muscles, or “modules”, which have been assumed to be structured to perform task-specific biomechanical functions (e.g., to provide body support and forward propulsion). Modular organization has been shown to explain muscle activity across a wide range of walking speeds, levels of body weight support and other combined movement tasks (e.g., [1]). However, no study has explicitly tested whether the modules would actually produce the biomechanical functions associated with them or even produce a well-coordinated movement. The purpose of this study was to generate muscle-actuated forward dynamics simulations of normal healthy walking using muscle activation modules identified using nonnegative matrix factorization as the muscle control inputs to a) assess whether the modules are sufficient to produce well-coordinated walking, and b) identify the contributions of each module to the necessary biomechanical walking sub-tasks of body support, forward propulsion and leg swing. This analysis will critically assess the functional output of the previously identified modular organization of muscle activity in walking and investigate whether it provides a foundation for the neuromotor control of human locomotion.
Studying the Non-Specific Surface Adhesion of Cancer Cells: A Novel Way to Characterize and Understand Cancer Metastasis
Authors: Tang Xin , Cappa Tony , Kuhlenschmidt Theresa B. , Kuhlenschmidt Mark S. , Saif Taher A.
Published: July 2013

Cancer deaths are mostly caused by the metastasis of the malignant cells, not by the parent tumor itself. During metastasis, cancer cells detach from the parent tumor, spread to different tissues via blood circulation or lymph system, and reattach to invade new tissues and organs. Adhesivity plays a crucial role throughout the metastasis process.
Dependence of Intervertebral Disc Pressure Generation on Load History
Authors: Hwang David , Yu Miao , Hsieh Adam H.
Published: July 2013

It has been thoroughly documented that low back pain is often associated with deregulated biological function and compromised mechanical behavior of the intervertebral disc. Therefore, intervertebral disc mechanics have long been thought of as important factors both in driving cell-mediated processes involved in degeneration and in distinguishing between healthy versus degenerate discs. The nucleus pulposus is an integral part of the mechanics of the disc, the key property being its ability to pressurize to resist and distribute compressive stress to the annulus fibrosus and the endplates. There has been a history of intradiscal pressure measurements in cadaveric as well as large animal studies; however, these studies have focused on the consequences of degeneration or the change in stress distribution by varying spinal orientations. In order to be able to relate local stresses induced in discs to changes in cellular function, such pressure measurements must be obtained from an animal model amenable to chronic disc loading. Rat tail discs have been one widely used laboratory model, but the discs are too small for measuring load-induced nucleus pressures using current sensor technology.
Age and Gender Differences in the Effects of Localized Muscle Fatigue on Joint Torques Used During Bipedal Stance
Authors: Wojcik Laura A. , Lin Dingding , Nussbaum Maury A. , Shibata Peggy A. , Madigan Michael L.
Published: July 2013

Work-related falls are still a major cause of injuries and fatalities, even after continuous efforts towards improving worker safety. Falls accounted for more than 20% of nonfatal occupational injuries and were the second leading cause of occupational fatalities in the United States [1,2]. Given projections showing an increasing number of workers over the age of 55 [3], the older population must be considered in assessing the risks and prevention of work-related falls.
A Comparison of Two Hip Stem Styles: Subsidence, Failure Load, and Bone Density
Authors: Kuxhaus Laurel , Dazen Derek , Hofer Andre , Sotereanos Nicholas G. , Miller Mark Carl
Published: July 2013

The design of the femoral components used in hip arthroplasty has evolved from a concept to a standard construct with a few variations. Attempts to remove less bone have become more important as revision surgery many years after primary implantation has become more common. The Mayo Conservative Hip Prosthesis (Zimmer, Inc., Warsaw, IN) was designed to preserve bone and to use broaches that do not require strict superior/inferior access to the femoral canal. The shape of the stem was intended to reduce the amount of subsidence following implantation. The taper in both the anterior-posterior and medial-lateral directions offered an interference fit to ensure rigidity. The VerSys Fiber Metal Taper (FMT) implant (Zimmer, Inc., Warsaw, IN) is a tapered, collarless implant that is coated proximally with fiber metal and has a polished distal tip. It is intended to be inserted without cement and has a successful history of clinical use. Preparation of the canal requires more superior/inferior access for broaching and preparation of the femur.
The Fluid Dynamic Effects Within the 12cc Penn State Pediatric Ventricular Assist Device When Altering the End Diastolic Delay
Authors: Cooper Benjamin T. , Roszelle Breigh N. , Long Tobias C. , Deutsch Steven , Manning Keefe B.
Published: July 2013

Congenital heart disease is the most common and leading cause of birth-defect related deaths [1]. While many of these patients have damaged or deformed hearts that require transplantation, recovery may be possible for a select population [2]. Extracorporeal membrane oxygenation or ventricular assist devices are often used in a bridge-to-recovery situation to sustain a patient with the expectation of recovery of natural ventricular function [3].
Evaluation of Fracture Load in Human Radius via Cohesive Finite Element Modeling
Authors: Ural Ani
Published: July 2013

Osteoporotic and age-related fractures are a significant public health problem. One of the most common osteoporotic fracture sites in the aging population is distal radius. There is evidence in the literature that distal radius fractures (Colles’ fracture) are an indicative of increased risk of future spine and hip fractures [1]. Therefore, developing new methods for accurate evaluation of human radius fracture risk is necessary. The previous studies showed that geometrical properties of the radius correlate with its fracture load [2]. However, the combined effect of geometrical and material properties on fracture load has not been studied.
Measurement of Local Strains in Intervertebral Disc Anulus Fibrosus Tissue Under Dynamic Shear: Contributions of Matrix Fiber Orientation and Elastin Content
Authors: Michalek Arthur J. , Buckley Mark R. , Bonassar Lawrence J. , Cohen Itai , Iatridis James C.
Published: July 2013

Physiological levels of bending and flexion of the intervertebral disc are known to result in large shear strains of the anulus fibrosus (AF) tissue [1]. While microstructural shear is often implicated as a likely failure initiator [2], it is unclear what series of cascading mechanisms act to transfer shear from the tissue scale down to the micron scale. In particular, a consensus has yet to be reached on the degree to which interlamellar sliding contributes to transverse shear deformation. Elastin plays an important role in radial tensile behavior of the AF [3], however its function in shear has not been investigated.
Nitinol Peripheral Stents: A Computational Framework to Investigate the Stent Design From Lasercutting to Deployment
Authors: Conti Michele , Auricchio Ferdinando , De Beule Matthieu , Calabrese Emilio , Verhegghe Benedict
Published: July 2013

Cardiovascular disease (CVD), which is often related to atherosclerosis, is the most common cause of death in European countries [1].
The Design and Validation of a Device to Intraoperatively Measure Knee Stability During Total Knee Arthroplasty
Authors: Siston Robert A. , Maack Thomas L. , Van Gorp Cornel C. , Chaudhari Ajit M. W.
Published: July 2013

The success of a total knee arthroplasty is determined, in part, by the ability of a surgeon to adequately manage (or balance) the soft tissues surrounding the joint. Postoperative malalignment or imbalance of the collateral ligaments can lead to a lax joint and result in early loosening and instability, and leaving the knee too tight may cause stiffness and limited motion [1,2]. The severity and location of wear patterns on the polyethylene insert are also associated with knee stability from ligament balancing [3]. Establishing a balanced soft tissue envelope remains a challenge that is not always achieved [4], and instability, tightness, and wear that result from unbalanced knees may necessitate revision surgery [2,5] or result in reduced patient satisfaction.
Cross-Flow at Anterior Communicating Artery and Implication in Cerebral Aneurysm Formation
Authors: Jou Liang-Der , Mawad Michel E.
Published: July 2013

The anterior communication artery (ACOM) connects the right and left anterior cerebral artery and establishes contra-lateral flow, permiting perfusion of brain at both sides. While the artery itself is very short in length and small in size, 35% of ruptured aneurysms are found to form at the ACOM [1] and these aneurysms also rupture when they are small [2].