bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology Selected for City of Los Angeles Waste-Conversion Facility Sets New Standards for Sustainable Waste Management Using WTE
Authors: Meo Dominic , Zwahr Heiner
Published: July 2013

The technology selected by the Los Angeles Bureau of Sanitation for its new waste-conversion facility marks an unprecedented step forward in sustainable waste management. Developed by Green Conversion Systems (GCS) in Rye, New York, the proposed facility utilizes commercially-proven waste-treatment technologies which combine the proven benefits of a conventional materials-recycling facility (MRF) with technologies developed for the newest generation of waste-to-energy (WTE) facilities operating in Europe. As a result, the proposed plant will convert essentially all of the waste into electrical power and recyclable byproducts.

In the plant design developed by GCS, “black-bin” (post-curbside recycling) waste collected by the City of Los Angeles is treated in a two-step process:

• An advanced materials-recovery facility recovers almost 30 percent of the waste for recycling.

• The remaining waste is processed in an advanced WTE facility which produces electrical power and a range of commercial byproducts.

• More than 99 percent of the waste treated will be diverted from landfilling.

When the plant becomes operational, it will provide waste disposal at reasonable costs and several hundred direct and indirect jobs for the surrounding community.
Resource Recovery: The Contribution of Energy-From-Waste Plants
Authors: Koralewska Ralf
Published: July 2013

Energy-from-Waste plants using grate-based systems have gained world-wide acceptance as the preferred method for the sustainable treatment of waste. Key factors are not only the reduction of waste volume and mass and the destruction or separation of pollutants but also the efficient production and use of energy (electricity, district heating/cooling, process steam), compliant disposal and the recovery of resources from combustion residues (e.g. metals, rare earths). International requirements relating to energy efficiency and materials recovery by means of thermo-recycling in Energy-from-Waste plants call for the continuing development and optimization of existing technologies and concepts.

The technologies and processes for the recovery of reusable materials from dry-discharged bottom ash and from filter ash point to the key role that Energy-from-Waste plants are able to play in the efficient conservation of resources. It is primarily thermal treatment with dry discharge and subsequent processing of the bottom ash fractions that enables Energy-from-Waste plants to justify their status as universal recyclers. In addition to recovery of the energy inherent in the waste, the treatment of dry-discharged bottom ash is an important contribution to compliance with raw material and climate policies and to the promotion of closing the material cycle in general. Furthermore, dry bottom ash discharge represents a further step towards waste-free operation and “after-care-free” landfills.

This paper documents the potential of Energy-from-Waste plants for the recovery of resources and provides examples of recent developments and large-scale implementations of innovative recovery technologies in Europe.
Waste-to-Energy, State Renewable Portfolio Standards (RPS), and the Future of Renewable Energy
Authors: Brandes William F.
Published: July 2013

The world’s bleak economic outlook in the second decade of the 21st Century has placed a burden on the world’s attempts to promote a more sustainable system of energy generation. Increasingly, the cost of regulatory programs designed to protect the environment and foster a lower carbon economy has become of significant concern. A recent example is the retraction of the U.S. EPA’s revision of the Ozone National Ambient Air Quality Standards, cited as part of a larger effort aimed at “reducing regulatory burdens and regulatory uncertainty, particularly as our economy continues to recover”, in a statement issued recently by the White House.
Practical Experience on Optimization of Combustion With Expert Systems From 12 WTE Plants in Europe and China
Authors: Danielsen Asger
Published: July 2013

Process optimization of Waste to Energy plants (WtE plants) is of particular interest because control performance is crucial for the profitability of the overall operation of the plant.

WtE plants represent very large investments and an optimal efficiency in operation is crucial for the return of the investment. Process optimization including optimal control of the abnormal operating situations when the waste quality is out of the normal range is thus very attractive in order to increase the profitability and efficiency of the waste incineration operations.

This presentation will describe how high-level control based on expert system can be used in a practical and convenient way to provide a more efficient operation of a WtE plant and provide a capacity increase of 3–6% or more and thereby be a very attractive investment for an existing or new WtE plant operator.
Aero-Shields: New Product Improves Boiler Performance and Maintenance
Authors: Epelbaum Greg , Tanguay Eric
Published: July 2013

Aero-Shields were developed by Covanta Energy in 2005 to address excessive fouling and accelerated tube metal wastage in certain heat transfer areas of a large Municipal Solid Waste (MSW) fired boiler. Computational Fluid Dynamic (CFD) modeling and a Cold Flow model were used to investigate flue gas flow distribution, velocities, temperatures, and other parameters in specific areas of the boiler. The intent of this effort was to identify the problematic areas and develop a solution to better distribute gas flow within these specific areas of the boiler.

The result of this development effort was named “Aero-Shield”. The Aero-Shield provides a dual benefit of being a tube-shield and gas baffling device by incorporating extended tapered sides. The shape, size and installation location was developed through the use of CFD modeling. Initial testing of the shields was performed in December 2005 at the Lee County facility Boiler#2 at the top and bottom of the third pass. The Lee County boiler is a typical horizontal boiler design using Martin GMBH technology to process solid waste.

This paper demonstrates how CFD modeling plays an extremely important role in designing and optimizing Aero-Shields for new applications. It also describes additional applications which have been tested in multiple facilities and boilers types since 2005. It covers design guidelines for the material, geometry, and installation procedure. The paper will also highlight a number of benefits which have been confirmed through extensive field testing which include:

• Significant heat transfer increase in a targeted boiler area. This increases boiler efficiency and generates additional MWs at the same fuel rate.

• In Energy-from-Waste (EfW) applications, capital and maintenance costs are often more important than saving fuel. Aero-Shield applications provide significant savings by requiring less heat surface for the same heat recovery in a targeted boiler component.

• Reduced ash deposits which results in reduced maintenance.

• Improved gas flow distribution allows Aero-Shields to reduce peak gas temperatures and velocities, resulting in lower wastage rates for critical boiler components.

• Simple, quick, and economical installation: typically performed in a few hours.

Covanta currently has a patent pending on this application and product. Additional testing is ongoing to address other areas within the boiler that may benefit from this technology recognizing that the “Aero-Shield” is a customized solution for each application.
Normal Carotid Bifurcation Hemodynamics in Older Adults: Effect of Measured vs. Allometrically-Scaled Flow Rate Boundary Conditions
Authors: Hoi Yiemeng , Wasserman Bruce A. , Steinman David A.
Published: July 2013

A recent study demonstrated that certain geometric features of young adult carotid bifurcations are surrogate markers of disturbed flow [1]. However, as the carotid bifurcation ages, the bifurcation and flow waveform changes its geometry and dynamics, respectively [2, 3]. In addition to confounding systemic risk factors, such changes may interrupt homeostasis, potentially altering the likelihood of disturbed flow and atherosclerotic disease in the aging carotid bifurcation. Despite this, disturbed flow in aged bifurcations is typically inferred from image-based computational fluid dynamics (CFD) approaches using representative young and healthy adult flow waveforms.
Determining the Threshold of Stability During Unstable Sitting
Authors: Tanaka Martin L. , Nussbaum Maury A. , Ross Shane D.
Published: July 2013

Diverse parameters have been developed to quantify spinal stability or system robustness. Kinematic variability (KV) has commonly been used based on the assumption that more robust systems will be able to more effectively reduce system variability. Some of these KV parameters include displacement, standard deviation, RMS area and path velocity of the center of mass (COM) or center of pressure (COP). In addition, stability diffusion analysis and Lyapunov exponents have been used to quantify stability, where lower diffusion or divergence rates indicate a more stable system.
Average Periosteal Stress of the Proximal Femur Before and After Cementless Total Hip Arthroplasty
Authors: Yutzy Joseph D. , Bardy Erik R.
Published: July 2013

Cementless Total Hip Arthroplasty (THA) is a standard surgical technique for the treatment of several types of joint diseases and damages including, but not limited to, osteoarthritis and femoral neck fracture [1]. An estimated one half to one million total hip replacements are performed each year [2]. Two drawbacks to THA are (1): micromotions as a result of improper implant fit in the bone cavity [1], and (2): stress shielding due to unnatural stress concentrations near the implant [3]. The latter causes bone resorption in other areas found in the bone-implant interface [1]. Therefore, the geometry and size of the implant is a major factor in determining cortical stress distributions and stress shielding [4].
A One-Step Method to Fabricate PLLA Scaffolds With Deposition of Bioactive Hydroxyapatite and Collagen Using Ice-Based Microporogens
Authors: Chen Yun , Li Jiashen , Tuan Rocky S. , Mak Arthur F. T.
Published: July 2013

Scaffolding is an essential issue in tissue engineering. We have recently developed an approach to generate HA/collagen coated poly(lactic-glycolic acids) scaffolds using a porogen-leaching method [1]. The approach involves a two-step process with coating first on the paraffin microspheres and then using the coated microspheres both as the porogens and the vehicles to transfer the bioactive apatite/collagen coating. In this study, we describe an advancement of the porogen-based technology using ice-based microporogens to deposit multiple bioactive agents into the desired scaffold in a single step.
Characterization of Regional Mechanical Property Anomalies in Tensile Test Specimens
Authors: Brodland G. Wayne , Horst Caleb R. , Veldhuis Jim H. , McDonald Matthew
Published: July 2013

This study demonstrates that regional mechanical property anomalies can be identified in tensile specimens using high-resolution, multi-point tracking and suitable analysis software. Identification of such regions is important for test validation and for accurate interpretation of force-displacement data. Biaxial tensile tests on bovine peritoneum showed that regional strains can vary by a factor of 3 within a single specimen, and analyses that ignore such variations are shown to produce stress-strain graphs that are substantially in error.
An Experimental Study of In Vitro Transdermal Drug Delivery Assisted by Cryopneumatic Technology
Authors: Sun Feng , Anderson Robert , Aguilar Guillermo
Published: July 2013

Transdermal drug delivery (TDD) is a promising alternative to conventional drug delivery approaches, such as oral or injectable routes. In comparison, the primary benefits of TDD include [1]: 1) avoidance of first pass metabolism and other variables associated with the GI tract such as pH changes and gastric emptying time. 2) sustained and controlled delivery over a prolonged period of time. 3) reduction in side effects associated with systemic toxicity. 4) improved patient acceptance and compliance. 5) direct access to targeted or diseased site, e.g. treatment of skin disorders. 6) ease of dose termination in the event of any adverse reactions either systemic or local; 7) convenient and painless administration; 8) ease of use and reduction of overall health care treatment costs; 9) viable alternative in circumstances where oral dosing is not possible (in unconscious or nauseated patients).
Electromechanical Control of Atrium Function
Authors: Svobodova Miroslava , Di Martino Elena S.
Published: July 2013

The heart is a very efficient mechanical pump whose function is to controls the blood flow in the body. Two physical systems, namely mechanical for the pumping action and electrical for the control interact within the heart. Cardiac function can only be studied if both mechanical and electrical systems are considered. In particular, we are interested in the electromechanical control of the atrium pump function which is less studied then the electromechanical control of the ventricle pump function and none the less is a crucial factor in the development of atrial fibrillation.
Mechanical Stimulation Enhances Collagen Synthesis in Periosteum-Derived Cartilage
Authors: Ravetto Agnese , Kock Linda M. , van Donkelaar Corrinus C. , Ito Keita
Published: July 2013

High prevalence of osteoarthritis and poor intrinsic healing capacity of articular cartilage create a demand for cell-based strategies for cartilage repair. It is possible to tissue engineer cartilage with almost native proteoglycan content, but collagen reaches only 15% to 35% of the native content. Also its natural arcade-like structural organization is not reproduced. These drawbacks contribute to its insufficient load-bearing properties. It is generally believed that the application of mechanical loading during culturing will improve the mechanical properties. However, a suitable mechanical loading regime has not yet been established.
Pilot Study on the Enhancement of Irreversible Electroporation (IRE) With Carbon Nanotubes (CNT)
Authors: Arena Christopher B. , Rylander Marissa Nichole , Davalos Rafael V.
Published: July 2013

Non-thermal irreversible electroporation (IRE) is a new, minimally invasive technique that has shown great promise for the ablation of tumors [1]. The procedure involves placing electrodes into or around a targeted tissue and delivering a series of low energy (intense but short) electric pulses for approximately one minute. These pulses induce irreversible structural changes in the cell membranes of the targeted tissue that lead to cell death. Because IRE affects only a single molecular component of the treated area, the cell membrane, it is the first true molecular surgery. IRE has the ability to create complete and predictable cell ablation with a sharp transition between normal and necrotic tissue.
Surface and Bulk Stiffness of the Mature Porcine Cartilage-Like Tissue Repaired With a Scaffold-Free, Stem Cell-Based Tissue Engineered Construct (TEC)
Authors: Nansai Ryosuke , Ogata Mamoru , Takeda Junichi , Ando Wataru , Nakamura Norimasa , Fujie Hiromichi
Published: July 2013

Since the healing capacity of articular cartilage is limited, it is important to develop cell-based therapies for the repair of cartilage. Although synthetic or animal-derived scaffolds are frequently used for effective cell delivery long-term safety and efficiency of such scaffolds still remain unclear. We have been developing a new tissue engineering technique for cartilage repair using a scaffold-free tissue engineered construct (TEC) bio-synthesized from synovium-derived mesenchymal stem cells (MSCs) [1]. As the TEC specimen is composed of cells with their native extracellular matrix, we believe that it is free from concern regarding long term immunological effects. Fujie et al. found in a micro indentation test using an atomic force microscope (AFM) that the immature porcine cartilage-like tissue repaired with TEC exhibited lower stiffness as compared with normal cartilage in immature porcine femur [2], although the macro-scale stiffness of the repaired tissue was almost same as that of the normal cartilage [3]. In the present study, we investigated the macro and micro-compressive properties of mature porcine cartilage-like tissue repaired with TEC.
Mechanical Properties of the Epidermis and Stratum Corneum Determined by Submicron Indentation In Vitro
Authors: Geerligs Marion , v. Breemen Lambert C. A. , Peters Gerrit W. M. , Ackermans Paul A. J. , Oomens Cees W. J. , Baaijens Frank P. T.
Published: July 2013

The outer skin layers are important drug and vaccine delivery targets in the treatment of diseases. These skin layers possess some important characteristics making them favorable sites for pain-free delivery with minimal damage: a rich population of immunologically sensitive cells as well as the lack of blood vessels and sensory nerve endings [1]. Until today, however, the development of effective cell targeting methods is acquainted with many challenges. A collective shortcoming is a poor understanding of the key mechanical properties of the outer skin layers, e.g. the stratum corneum and epidermis. The anisotropic, dynamic and very complex nature of skin makes it difficult to perform proper mechanical testing as well as to obtain reliable, reproducible data. The stratum corneum is an effective physical barrier of dead cells with a “brick-and-mortar” structure, while the viable epidermis mainly consists of actively migrating keratinocytes constantly undergoing massive morphological and compositional changes. As a consequence, the structure differences among the skin layers lead to significant variations in mechanical properties. Since there is no method available to determine the mechanical behavior of isolated viable epidermis in vivo or in vitro, the mechanical behavior of epidermis and stratum corneum only are investigated here. A commercially available indentation system has been adapted to enable the measurement of these thin soft tissues in an in vitro set up. Combining the outcomes of the two skin layer types leads to an assessment of the contribution of the viable epidermis to the mechanical behavior of skin. To our knowledge, no data have been published yet regarding mechanical bulk properties of (viable) epidermis, while no consistency exists with respect to those of the stratum corneum.
Biomechanical Comparison of Lumber Disc Prostheses: ProDisc-L, Charité, and Maverick Disc Implant Systems
Authors: DiAngelo Denis J. , Foley Kevin T. , Morrow Brian , Wong Peter , Kelly Brian P. , Kiehm Kelly , Sin Anthony , Bertagnoli Rudolf
Published: July 2013

Interest in lumbar disc arthroplasty as an alternative to fusion surgery continues to grow. The goal of disc arthroplasty is to replace the diseased disc while preserving and/or restoring motion at the operated spinal level. Different paradigms exist in the design of total disc arthroplasty devices. The purpose of this study was to compare the in vitro biomechanics of a more constrained ball-and-socket design (Prodisc-L, Synthes Spine and Maverick, Medtronic) and a less constrained mobile-bearing design (Charité, DePuy). The biomechanical performances of the disc prostheses were compared to the fused and harvested spine conditions.
Study of Tumor Microenvironment to Vascular Normalization Based on 3-D Simulation of Tumor Haemodynamics
Authors: Wu Jie , Xu Shixiong , Long Quan
Published: July 2013

In recent years, anti-angiogenic therapy has been extensively studied in both preclinical and clinical settings. Experimental studies have approved its effects on the normalization of tumor vasculature as well as the microenvironment in tumors [1]. However, little is known about how tumor microenvironment is affected by the changes in structure of vasculature or transport properties of vessels and interstitium that are associated with anti-angiogenic therapy, since the experimental data are difficult to obtain [2].
Ultimate Strength of the Adventitia and Media of Human Atherosclerotic Carotid Arteries in the Axial and Circumferential Directions
Authors: Teng Zhongzhao , Hoffman Allen H. , Zheng Jie , Woodard Pamela K. , Tang Dalin
Published: July 2013

The abrupt closure of an artery by an occlusive thrombus is the main cause of myocardial infarcts and other thrombotic sequelae of atherosclerosis. This thrombosis is often associated with rupture of an atherosclerotic plaque [1,2]. Histology has shown that most rupture sites are also sites of increased mechanical stress [2]. It has been widely accepted that atherosclerosis leads to locally increased stresses in the region of lesions. However, validation of this hypothesis has been impeded by a lack of experimental data on the material strength of atherosclerotic tissues. Knowledge of mechanical properties of human atherosclerotic tissues is essential for understanding the rupture mechanism and also for creating more accurate computational models for predicting fatal cardiovascular events [3]. Moreover, an increased understanding of the mechanical properties of atherosclerotic tissue is important for developing greater insight into the pathophysiology of the cardiovascular system and as well as for predicting the outcome of interventional treatments such as balloon angioplasty.
Healing Progress of Fractured Bone: A Longitudinal Study
Authors: Jiang Feifei , Chen Jie , Komatsu David E. , Li Shuning
Published: July 2013

In orthopedics research, assessment of fracture healing progress is vital for evaluating treatment strategies and drug effects. Currently, biomechanical testing represents the ‘gold standard’ for determining the extent of healing, with the parameters of stiffness and strength most often reported. Unfortunately, such testing requires destructive examination of samples, which allows healing to be checked at only one time-point per animal. Thus, evaluation of healing requires large sample sizes to achieve statistical power. In contrast, longitudinal studies of individual animals allows for self-comparison, which is more reliable, and can be used to evaluate bone healing as time elapses. Recently, longitudinal radiographic assessment of bone healing in rats, using parameters such the level of bone mineralization, morphological changes, and distribution of the mineralized bone, has been reported. However, the ability to quantify the biomechanical properties of healing bones based on longitudinal radiographic images provides an tremendous opportunity to increase the value of such studies.
Time-Dependent Lateral Transmission of Force in Skeletal Muscle
Authors: Gao Yingxin , Wineman Alan S. , Waas Anthony M.
Published: July 2013

The composite structure of skeletal muscle is composed of muscle fibers and an extracellular matrix (ECM) framework. This framework is associated with different levels of structure: (a) epimysium, that ensheaths the whole muscle; (b) perimysium, that binds a group of muscle fibers into bundles and (c) endomysium that surrounds the individual muscle fibers. The properties of ECM components and their interaction with muscle fibers determine the overall mechanical properties of the whole muscle. Previous studies have experimentally demonstrated that stress could be laterally transmitted through the ECM [1]. The ECM is thus an essential element in mechanical function of the muscle [2]. The most widely used model describing load transfer between a discontinuous fiber and matrix is the shear lag model, originally proposed by Cox [3]]. This model centers on the transfer of tensile stress between fibers by means of interfacial shear stresses and shear deformation of the matrix. In this paper, a modified shear lag model is developed to investigate the time-dependent mechanics of stress transfer between activated muscle fibers and the surrounding strained ECM.
Biphasic Poroviscoelastic Modeling of the Unconfined Compression of Porcine Liver Tissue
Authors: Raghunathan Smitha , Sparks Jessica L.
Published: July 2013

Liver injuries (blunt and penetrating) account for 32% of all abdominal injuries and are seen in approximately 5% of all trauma admissions (1). Motor vehicle crashes are the most common source of blunt liver injuries (1) and understanding the mechanical response of the liver to loading may facilitate the improvement of vehicle safety.
Shear Stress and Angiotensin II in the Development and Localization of Abdominal Aortic Aneurysms
Authors: Consolini Michelle , Passerini Tiziano , Piccinelli Marina , Fornwalt Brandon , Willett Nick G. , Long Robert C. , Veneziani Alessandro , Oshinski John N. , Taylor W. Robert
Published: July 2013

Abdominal aortic aneurysms (AAAs) develop in the infrarenal aorta of humans and in the suprarenal aorta of apoE−/− mice infused with angiotensin II (AngII). Oscillatory wall shear stress in the infrarenal human abdominal aorta is driven by the flow to the gastric arteries, the lumbar curvature and the capacitance of the lower extremities [1]. Two of these factors, the lumbar curvature and the capacitance of the lower extremities, are significantly different in mice than in humans. Therefore, we hypothesized that the differences in localization of AAAs between species is explained by differences in the pattern of wall shear stress via the shear-regulated modulation of inflammatory pathways involving AngII.
5R Manipulator Robotic Arm for a Power Wheelchair Used by BCI Unit
Authors: King Christine E.
Published: July 2013

Although robotic arms for power wheelchairs have been developed, existing models have limitations for people who cannot use joystick controls or who need to maneuver in small spaces. This project addresses these problems by developing programs to link brain computer interface communication systems to robotic controls and by designing a smaller and more compactable robotic manipulator.
Bio-Mechanical Aspects of Short Peripheral Catheter Thrombophlebitis
Authors: Rotman Oren , Shav Dalit , Zaretsky Uri , Einav Shmuel
Published: July 2013

Venflons, or Short Peripheral Catheters (SPC), are the most common intravenous devices being used in medical practice, particularly in hospitals and intensive care units. SPC is usually inserted into veins of the upper extremities to administer fluids, medications, blood products or for prophylactic use before procedures. It has been reported that 40–80% of hospitalized patients were treated with SPCs [1, 2]. Short Peripheral Catheter Thrombophlebitis (SPCT) is the most frequent complication of treatment with, characterized by pain, tenderness, warmth, erythema, swelling and palpable thrombosis of the cannulated vein. SPCT causes patients discomfort and generally leads to catheter removal and insertion of a new catheter at a different site [3]. SPCT is a sterile inflammation [2, 3], and its pathogenesis is not well understood. Several mechanisms have been suggested for SPCT pathogenesis, such as chemical irritation of the endothelium due to infusate or catheter material, or that vein wall injury combined with stasis cause an inflammation response and thrombosis [4, 5].
Simulation of Aneurysm Growth With Stepwise Updating of Hemodynamic Loads Using an MRI-Based Geometric Model
Authors: Sheidaei A. , Hunley S. C. , Raguin L. G. , Baek S.
Published: July 2013

Computer simulations of vascular tissue adaptation under various physiological and pathological conditions have emerged as a new area of research and aided researchers in their understanding of stress-mediated growth and remodeling (G&R) in these structures. With advances in computational biomechanics and biomedical imaging techniques, combinations of these advanced methods will provide promising tools for medical diagnosis and surgical planning in the future (e.g., [1]). Recently Figueroa et al. [2] presented a new computational framework that brings advances in computational biosolid and biofluid mechanics together in order to exploit new information on the biology of vascular growth and remodeling (G&R). Although the framework presented in their paper was generalized for simplicity, they did illustrate the effectiveness of this framework by applying it to a fusiform aneurysm growth with idealized geometry. In the present work, we employ this framework and test it on an anatomically realistic model of abdominal aortic aneurysm (AAA) growth. Similarly to Figueroa et al., when the stress-mediated kinetics only depends on intramural stress, the shape of the aneurysm and the expansion rate are similar to the results from the computation without using an iterative loop. However, we expect that when the stress-mediated kinetics depends on either shear or other hemodynamic components, the evolution of an AAA can change significantly.
Secondary Structures and Mechanical Properties of Biomimetic Protein Polymers
Authors: Teng Weibing , Cappello Joseph , Wu Xiaoyi
Published: July 2013

Silk may possess superior mechanical strength while its resilience is very poor. In contrast, elastin in human arteries is very soft but extremely durable with an estimated half-life of 70 years. By combing polypeptide sequences derived from native silk and elastin, we have produced a series of silk-elastin-like proteins (SELPs), which have displayed a set of outstanding properties such as good biocompatibility and controllable biodegradation rates [1]. In this study, we will examine the crystallization of the silk-like blocks and the crosslinking of the elastin-like blocks, as well as their influences on the mechanical behavior of SELPs. The ultimate goal of this study is to explore the potential of SELPs for applications in the engineering of load-bearing tissues such as arteries.
Osmotic Stress Affects Nuclear Morphology and Genome Architecture
Authors: Finan John D. , Guilak Farshid
Published: July 2013

The spatial organization of the genome influences its function [1]. Therefore, physical signals that deform the nucleus and the genome within may directly affect gene transcription and translation. In articular chondrocytes, nuclear deformation in response to osmotic stress is not sensitive to actin organization [2]. However, articular chondrocytes differ from most mammalian cells in that they remain round with cortically organized actin in monolayer culture. Adherent cells such as adipose stem cells (ASCs) spread in monolayer culture, forming a more typical, highly bundled actin cytoskeleton. These actin bundles exert tensile stress on the nucleus so we hypothesized that the osmotic sensitivity of the cell nucleus would be modulated by actin organization in ASCs. The osmotic sensitivity of the nucleus was quantified by measuring changes in the size and shape of the nucleus and the spatial arrangement of the chromatin within using 3D confocal microscopy.
Dynamic Optimization of Maximum-Effort Human Sprinting
Authors: Miller Ross H. , Umberger Brian R. , Hamill Joseph , Caldwell Graham E.
Published: July 2013

Maximum speed is an important parameter for sprinting humans, particularly in athletic competitions. While the biomechanics of sprinting have been well-studied [1–3], our understanding of biomechanical limits to maximum speed is still in its infancy. Previous studies have suggested a speed-limiting role for the force-velocity relationship of skeletal muscle [2], but these theories are difficult to verify experimentally due to the difficulty in observing and manipulating human muscle dynamics in vivo.
Effect of Compressive Load on the Mechanical Property of a Stem Cell Based Self-Assembled Tissue Derived From Synovium
Authors: Emura Ryo , Ogawa Atsushi , Saito Kei , Ando Wataru , Nakamura Norimasa , Fujie Hiromichi
Published: July 2013

Articular cartilage has superior functions such as impact absorption and low friction, although their healing capacities are limited. It is one of potential options for the repair of articular cartilage to use cell-based therapies. We have been developing a novel tissue-engineering technique for the repair of cartilage which involves a stem cell-based self-assembled tissue (scSAT) derived from synovium. As the scSAT is a scaffold-free contrust composed of cells with their native extracellular matrix, it is free from concern regarding long-term immunological effects. The scSAT is expressed as tissue engineered construct (TEC) when it is used for cartilage repair. Previous studies indicated that the mechanical properties of cartilage-like tissues repaired using the scSAT were slightly inferiorer to those of normal cartilage. We have a hypothesis that the mechanical properties of the cartilage-like tissues are improved if the scSAT is subjected to an adequate compressive stimulation in vitro before implantation. The present study was conducted as a preliminary study to determine whether static compression improves the mechanical property of the scSAT for more advanced regenerative medicine to cartilage injuries and degeneration.
A New Stent for Direct Treatment of Intracranial Aneurysms
Authors: Zhou Xiang , You Zhong
Published: July 2013

The intracranial aneurysm is a weak region in the wall of an artery in the brain, where dilation of the artery wall may occur. Because the wall of the aneurysm is very thin, lacking the normal layer structure found in healthy arteries, it is easy to rupture and leads to subarachnoid hemorrhages [1, 2]. Current methods for treating the intracranial aneurysms are surgical clipping and endovascular coiling [3]. In the surgical clipping method, a surgical clip is placed across the neck of the aneurysm through open surgery. The risk of this method is high, especially for elderly or medically complicated patients. In endovascular coiling, one or more coils are delivered into the aneurysm from a remote incision on the artery to trigger a thrombus inside the aneurysm sac. This method is less invasive and therefore safer compared to surgical clipping. However, it is less suitable for treating wide-necked aneurysms because the coils can not stay permanently inside the aneurysm sac. To solve this problem, stents have been used in association with coils [4]. In this procedure, a stent is first placed across the neck of the aneurysm, serving as a scaffold inside the artery lumen. Then, the coils are delivered into the aneurysm through the interstices of the stent. Although stent-assisted coiling is superior to using coils alone for the treatment of the wide-necked aneurysms, it is more complicated and requires longer operation time. Besides, neither of the coiling embolization methods can be used for treating the aneurysms which lack a defined saccular component.
Static-Strain-Induced Adaptation of Fibrous Tissue
Authors: Foolen Jasper , van Donkelaar Corrinus C. , Soekhradj-Soechit Sarita , Huiskes Rik , Ito Keita
Published: July 2013

Fibrous tissues have the ability to adapt to their mechanical environment. Adaptation can be guided by the direction and magnitude of the imposed load, leading to structural changes and altered mechanical properties. This is important for proper functioning of all fibrous tissues, especially those with a load bearing capacity such as tendons, ligaments, and tissue-supporting fibrous sheets. The mechanism by which fibrous tissues adapt to alterations in their mechanical environment remains unresolved, and such knowledge will be helpful to guide repair and engineering of artificial fibrous tissues.
Development of a Patient-Specific Nonlinear Finite Element Model for the Simulation of Lung Motion During Cancer Radiation Therapy
Authors: Eom Jaesung , Shi Chengyu , Xu George , De Suvranu
Published: July 2013

Respiratory motion causes either over-dose to the tumor or under-dose to the organ at risk in radiation therapy treatment for cancer. In order to characterize the motion, a nonlinear finite element model of the lungs has been developed based on 4D computed tomography (CT) data of a cancer patient with a tumor in the right lung. Pressure-volume (PV) curve data was applied to deform the model in real time. Realistic results are obtained when contact conditions are imposed between the pleura and the thoracic cavity.
Microdialysis Technique for Quantifying Drug Concentration in Human Intervertebral Discs
Authors: Han Hyun Kyu , Buckley Jenni M. , Kursa Kathy , O’Neill Conor , Lotz Jeffrey C.
Published: July 2013

New diagnostic and treatment techniques for chronic lower back pain involve localized drug delivery into the lumbar intervertebral disc [1,2]. A better understanding of these new techniques could be gained by measuring drug concentration at specific intradiscal locations at different time points [1]. Currently, there are no established methods for quantifying real-time in situ drug concentrations in the human intervertebral disc; however, injection profiles have been successfully characterized in pig disc, human brain, adipose tissue, and blood using microdialysis [3,4,5]. This technique involves continuous sampling of interstitial fluid via semi-permeable membranes mounted on miniature, implantable catheters [6]. Given the success of microdialysis in characterizing the real-time composition of other poroelastic tissues, we hypothesize that this method will be similarly successful when applied to human lumbar disc.
In Silico Force-Induced Unbending of αVβ3 Integrin
Authors: Chen Wei , Lou Jizhong , Hsin Jen , Schulten Klaus , Zhu Cheng
Published: July 2013

Integrins are type I transmembrane heterodimers that consist of two noncovalently associated α- and β-subunits. They mediate cell-cell, cell-extracellular matrix, and cell-pathogen adhesions in a wide variety of physiological and pathological processes [1].
External Rotation Ankle Injuries: Investigating Ligamentous Rupture
Authors: Villwock Mark R. , Meyer Eric G. , Powell John W. , Haut Roger C.
Published: July 2013

Ankle sprains are one of the most common sports injuries [1], accounting for 10% to 15% of these injuries [2]. The severity of injury varies greatly and the player’s recovery time is related to the structures involved and their degree of damage. In contrast to the soft tissue injuries reported in many clinical studies on the ankle, experimental studies have typically generated a high frequency of bone fracture when the foot/ankle complex is externally rotated [3–5]. In a majority of these manuscripts, the cadaveric test specimens are of advanced or unknown age. These variables may substantially affect both the failure load and the mode of failure in the joint, since most ankle sprains occur in people under the age of 35 years [6].
Regional Glycosaminoglycan Coverage of Healthy Rabbit Menisci
Authors: Killian Megan L. , Lepinsky Nicole M. , Isaac Dan I. , Haut Roger C. , Haut Donahue T. L.
Published: July 2013

The meniscus is an important load-bearing structure in the knee, as it provides load distribution and cushioning properties during weight-bearing activities. The compressive modulus and permeability of the meniscus is attributed to the tissue’s glycosaminoglycan (GAG) content, as charged proteoglycan side chains allow for tissue swelling and resistance to compression [1]. The distribution of sulphated GAGs throughout the meniscus has not been thoroughly documented. Although load differs across the knee joint, few researchers have investigated medial/lateral and coronal differences in meniscal architecture and GAG distribution [2, 3]. It is hypothesized that the distribution of positive histological staining for sulfated GAGs will differ across spatial regions of rabbit menisci. Primarily, it is hypothesized that regions of the menisci that likely see higher loading will demonstrate an increase in sulfated GAG-positive staining area.
High-Fidelity Finite Element Mesh Generation for Fluid-Structure Interaction Analysis of Cerebral Aneurysms
Authors: Zhang Yongjie , Wang Wenyan , Liang Xinghua , Bazilevs Yuri , Hsu Ming-Chen , Kvamsdal Trond , Brekken Reidar , Isaksen Jørgen
Published: July 2013

Nowadays approximately 3–6% of the population is estimated to have unruptured cerebral aneurysms. The rupture risk of aneurysms can be predicted by using computational tools and patient-specific models. As an ideal method, we can assess the risk factors by determining the blood tension and the material strength of the wall tissue in the aneurisms. Although it is hard to obtain aneurismal material strength without invasive measurement, it is possible to estimate the wall tension by numerical simulation [1].
Mechanical Properties of the Porcine Coronary Artery
Authors: van den Broek Chantal N. , van der Horst Arjen , Rutten Marcel C. N. , van de Vosse Frans N.
Published: July 2013

Knowledge of the mechanical properties of arteries is important to understand vascular function during disease and the effect of interventions, such as PTCA treatment. A mechanical model of the vascular tree would facilitate the improvement of (balloon-)catheters and stents. The aim of this research is to propose general parameter values for the fiber-reinforced material model as proposed by Driessen et al. (2005) that can describe the arterial wall behavior of the porcine left anterior descending coronary artery (LAD, fig. 1a) at physiological axial stretch.
Initial Stress and Nonlinear Material Behavior in Patient-Specific AAA Wall Stress Analysis
Authors: Speelman Lambert , Bosboom E. Mariëlle H. , Schurink Geert Willem H. , Buth Jaap , Breeuwer Marcel , Jacobs Michael J. , van de Vosse Frans N.
Published: July 2013

An abdominal aortic aneurysm (AAA) is a local dilation in the abdominal aorta of more than 50% of the original diameter and occurs in about 1 of 20 men over 65 years of age [1]. The largest threat for an AAA is rupture. Aortic repair is considered when the risk of rupture exceeds the risk of the surgical procedure. Currently, clinicians use the maximum AAA diameter as rupture risk estimator. A higher sensitivity and specificity was reached by computing the maximum AAA wall stress with finite element analysis, thus incorporating the total AAA geometry [2].
Osteocytes in Bone Can Regulate the Turnover of Adjacent Mineralized Growth Plate Cartilage
Authors: Cox Lieke G. E. , van Donkelaar Corrinus C. , van Rietbergen Bert , Huiskes Rik , Ito Keita
Published: July 2013

It is generally believed that bone remodeling is controlled by osteocytes, which act as mechanosensors and regulate the activity of osteoblast and osteoclast cells [1,2]. Osteocytes seem suitable for this function, since they are the most abundant cell type of bone and they form an extensive network of cellular processes by gap junction connections to each other, lining cells, and osteoblasts [1,3].
Length and Sequence Dependence of the Elasticity of Alpha Helices and Coiled-Coils
Authors: Lakkaraju Sirish Kaushik , Hwang Wonmuk
Published: July 2013

Fibrous proteins made by α-helices, one of the most elementary protein secondary structures, have various mechanical roles in a sub cellular environment. An α-helix is wound in a right-handed fashion due to hydrogen bonding between the C=O and the N-H atoms across every i and i+4th residues in the polypeptide chain. Previous approaches characterizing mechanical properties of α-helices treated them as homogenous and linear elastic rods. Stiffness is typically expressed in terms of persistence length lp (∼100nm from Kb∼3×10−28 Nm2, lp = Kb/kT: Kb, the bending stiffness, k the Boltzmann constant and T = 300 K, the temperature) [1–3]. In this study, we show that bending stiffness depends on the length of the filament, due to inherent non-bonded attractions. In particular, non-bonded attraction introduces a new length scale, critical buckling length, beyond which the filament can no longer remain linearly elastic. These results suggest that non-bonded attractions can significantly affect elastic properties of biofilament systems such as the cytoskeleton. Furthermore, we find that while elasticity of a single α-helix is largely independent of its amino acid sequence, α-helical coiled-coils have stronger sequence dependence, and in the case of tropomyosin molecule, we find regional variations in the flexibility which may have functional implications in its actin binding properties and muscle contraction.
The Effects of Joint Posture and Segment Lengths on the Thumb-Tip Force Produced by Flexor Pollicis Longus
Authors: Goehler Craig M. , Murray Wendy M.
Published: July 2013

The ability to hold an object between the thumb and the lateral aspect of the index finger (lateral pinch) is an important aspect of hand function. Previous studies suggest that current biomechanical models of the thumb do not accurately predict lateral pinch force [1, 2]. These studies modeled the thumb using simplified joint descriptions based on orthogonal and intersecting axes of rotation. A detailed anatomical study indicates that the axes of rotation of the thumb are actually both non-intersecting and non-orthogonal [3]. It has also been reported that the anatomical variability observed in the data support four different representations of thumb kinematics, all with non-intersecting and non-orthogonal axes [4].
A Constitutive Model for Preconditioining in Ligaments and Tendons
Authors: Sopakayang Ratchada , De Vita Raffaella
Published: July 2013

Collageneous tissues, such as ligaments and tendons, are viscoelastic materials: they creep under constant stress, relax under constant strain, and show hysteresis when cyclically loaded and unloaded [1]. Although these tissues are viscoelastic, researchers in biomechanics often study their “pseudo-elastic” properties after subjected them to “preconditioning.” Preconditioning is an experimental procedure consisting of loading and unloading biological tissues repeatedly until no further change between the loading and unloading stress-strain curves are observed. This procedure significantly affects the measurement of mechanical properties [2]. Unfortunately, because there is no standard preconditioning protocol used in biomechanical testing, comparison among different experimental studies that quantify the mechanical properties of biological tissues remains difficult [3].
Fusion of Electrospun Mats
Authors: Wright Lee D. , Young Rachel T. , Freeman Joseph W.
Published: July 2013

Electrospinning has become a popular technique investigated for tissue engineering applications. Electrospinning is unique because it is capable of producing small fibers (diameters ranging from several nanometers to several microns) in a nonwoven mat, which is similar to the architecture of the extracellular matrix (ECM) within tissues [1]. The microenvironment of the cells should be analogous to that of native tissue so that cellular growth and function are improved.
A Dynamic Speed vs. Accuracy Trade-Off (DSAT) Paradigm for Measuring and Training Grip Force Control for Stroke Population
Authors: Kim Nam H. , Wininger Michael , Forrest Gail , Edwards Thomas , Craelius William
Published: July 2013

A fundamental principle of human motor behavior states that the accuracy of targeted movements relates reciprocally to their speed. This is quantified by Fitts’ Law, wherein movement time (MT) and index of difficulty (ID), the log2 ratio of target distance (A) to target height (H) has logarithmic linear relationship; MT = a+b·log2(2A/H) = a+b·ID. The slope, b (seconds/bits), measures targeting performance as the time spent at each difficulty level, expressed as bits of information to be processed by the neuromotor system [1, 2]. Fitts’ paradigm is a common measure of the kinematic performance of the upper limb, but has not been applied to its dynamic performance. Herein, we developed a dynamic speed-accuracy trade-off (DSAT) test of grip force modulation, which can be used both for assessment and training.