bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Justification of the New Method of Determination of Wheel Pair’s and Rail’s Damage
Authors: Mgebrishvili Nikoloz , Sharashenidze Guri , Moistsrapishvili Manana , Sharashenidze Sergo , Kuparashvili Liana , Dolidze Mamuka , Kurtanidze Pavle , Gogishvili Natia
Published: February 2010

Development of modern railways largely depends on the control of intactness of the wheel pairs and rails. It is impossible to ensure safety and increase the speed of railway traffic without providing such control. Detection of the wheel pairs’ and rails’ wear and damage is one of the key problems of railway science. Many scientific works are accomplished and lot of devices are elaborated in this field, but the mentioned problem still remains urgent. In order to increase the traffic safety, the group of authors has proposed a constructional scheme of the mobile device for detection of wheel pairs’ and rails’ wear and damage, which will have increased accuracy of measurement. Increasing of accuracy of measurement is carried out on the basis of development of mathematical model, which provides the realization of equal wear of wheel pairs’ as well as ones no equal wear. By installation of the proposed device on each wheel pair of each railcar of the rolling stock, the automatic control of wheel pairs’ and rails’ condition will be achieved. Namely: -Detection of the worn out wheel pair and determination of wear degree; -Detection of the damaged wheel pair; -Identification of the worn out or damaged wheel pair. Besides, on the basis of elaborated mathematical model: -Detection of the worn out rail; -Detection of the damaged rail; -Identification of location of the worn out or damaged rail. The obtained information will be constantly connected to the locomotive computer system. Therefore, for checking rolling stocks, there will no longer be need to build expensive stationary systems, to move trains great distances for their inspection and in the result, the time lost for stoppage will be saved. So, with the help of proposed mobile device, the traffic safety increases and at the same time expenses for detection of wheel pairs’ wear and damage decrease, which results in significant economic effect.
Geometry Detector Teardown Results at CSX
Authors: Bowling Kim
Published: February 2010

CSX Transportation has purchased, installed and integrated eight Optical Geometry Detector sites. These detectors measure the wheelset’s angle of attack and lateral position with respect to the tangent track upon which they pass. The objective of this project was to determine the source of extreme geometry measurements. CSX performed 19 teardowns of cars that were identified by the optical geometry system. Many other cars with geometry exceptions have also had close inspections at the repair tracks. This report will summarize how the defects found relate to the geometry exception. CSX has primarily looked at trucks with progressive and repeatable tracking problems, which cover 87% of the geometry exceptions. Key truck measurements recorded include: circumferential wheel tape size, digital wheel profiles, side bearing set up height, center bowl dimensions, side frame length and the distance between the thrust lugs. Many of the geometry exceptions seem to have been caused by mismatched (or asymmetrical worn) wheels. Differences in the circumference force the axle to shift laterally and allow the wheel to continually flange on the gauge side of the rail.
Wayside Detection: Component Interactions and Composite Rules
Authors: Braren Hark , Kennelly Michael , Eide Erik
Published: February 2010

Every day railcars are setout for repair based on wayside detector absolute alarm limits. These alarms successfully identify most of the cars capable of causing derailments. There would be thousands of additional cars set out if these absolute alarms were lowered to the levels required to remediate the remaining cars capable of causing derailments. The rail industry cannot tolerate this level of setouts, nor can it tolerate derailments. A more focused approach is required. BNSF has developed a Composite Rules Engine (CRE), which combines and evaluates the data currently gathered by each individual wayside detection system. It is capable of pin-pointing the worst of the worst among the remaining cars exhibiting elevated detector readings. CRE provides BNSF the means of bridging its stand alone detection systems to provide one centralized alarming system. The CRE is able to combine the separate rule flows of: Acoustic Bearing Detectors (ABD), Machine Vision Systems (MVS), Truck Hunting Detectors (THD), Truck Performance Detectors (TPD), Hot Bearing Detectors (HBD), a Warm Bearing Detection System (WBDS), Hot / Cold Wheel Detectors (HW) and Wheel Impact Load Detectors (WILD). In summary, CRE targets cars with multiple low level indications that, individually, are of little concern, but collectively have the potential to cause derailments.
Fuzzy Analysis of Speech Metrics to Estimate Conductor Alertness
Authors: Shahidi Parham , Southward Steve C. , Ahmadian Mehdi
Published: February 2010

A Fuzzy Logic-based algorithm has been developed for processing a series of speech metrics with the ultimate goal of estimating train conductor alertness. The output is a single metric, which directly quantifies the alertness level of the conductor. The metrics were selected based on their correlation to alertness through processed speech, but without any interpretation of the spoken words or phrases. Metrics that are used include: speech duration, silence duration, word production rate and word intensity. The assessment of these metrics is an experience and human knowledge based task, which generates the need for a mathematical model to accommodate this special circumstance. The algorithm developed here uses Fuzzy Logic to cast the human knowledge base into a mathematical framework for the alertness estimation analysis. The core of this fuzzy system is a rule base consisting of fuzzy IF-THEN rules, which are derived from the existing knowledge about the effects of sleep deprivation on alertness such as Furthermore, the rules were inferred from actual voice recordings that were taken on board a train. This data was then used to create a classification scheme to determine which pattern in the speech indicates different levels of alertness from anxiety to fatigue. The simplicity of the underlying mathematical model in this approach enables this system to compute and output an alertness metric in real-time. The nature of this algorithm allows for the use of an arbitrary number of rules to classify the alertness level and therefore provides the ability to continuously develop and extend the rule base as new knowledge emerges. The resulting algorithm is a fast, multi-input, single-output system that is able to quantify the train conductor’s alertness level anytime speech is produced.
Fracture Mechanics Approach to Estimate Rail Wear Limits
Authors: Lyons M. L. , Jeong D. Y. , Gordon J. E.
Published: February 2010

This paper describes a systematic methodology to estimate allowable limits for rail head wear in terms of vertical head-height loss, gage-face side wear, and/or the combination of the two. This methodology is based on the principles of engineering fracture mechanics. The concept of applying the principles of engineering fracture mechanics to examine structural integrity was originally introduced by the U.S. Air Force, and is now embraced by the commercial aircraft industry. Aircraft structures are based on fracture mechanics (also referred to as damage tolerance) principles. Moreover, the approach in conducting rail integrity research sponsored by the Government is based on damage tolerance principles. The fracture mechanics methodology to estimate rail head wear limits is based on various assumptions regarding operational and environmental factors. These factors include rail size, foundation modulus, temperature difference, train speed, and rail test interval (i.e. tonnage between rail tests). This paper describes the methodology based on engineering fracture mechanics to estimate rail wear limits. In addition, results and sensitivity studies from applying the methodology are presented.
Control-Oriented Dynamic Modeling and Characterization of Magnetorheological Dampers
Authors: Spaggiari Andrea , Dragoni Eugenio
Published: February 2010

This work is about the dynamic modeling and the experimental testing of magnetorheological (MR) dampers. The main improvement of this work over former models is the identification of dynamic parameters that are independent of the working conditions and that vary only as a function of the current. A simple model is built on the basis of the literature with the aim of simplifying the effort in retrieving the parameters and in controlling the system. The excitation current is introduced in the model as a variable, not only reducing the amount of test needed to assess the parameters, but also obtaining a faster model that can be profitably used in motion control. A second order polynomial relationship between the applied current and the three variable parameters is found, showing a saturation effect at high currents.
Topology Optimization of Mechanical Structures Using Level Set Method
Authors: Kasaiezadeh Alireza , Khajepour Amir , Salehian Armaghan
Published: February 2010

This article introduces a novel algorithm in topology optimization of mechanical structures to achieve a desired compliance using the level set method. In contrast with the literature in this area that attempts to minimize the compliance of a structure, the present study concerns with an innovative formulation to reach a desired compliance. It is shown that a more comprehensive technique is required to achieve this goal.
Safety Clutches With Nickel-Titanium Shape Memory Alloys
Authors: Predki Wolfgang , Bauer Bjo¨rn
Published: February 2010

The ability of Shape Memory Alloys (SMA) to remind two different macroscopic shapes and to alter between these shapes by changing their temperature, leads to innovative approaches within drive technology. Especially Nickel-Titanium (NiTi) Shape Memory Alloys offer high actuating forces and adjustment travel in combination with high cycle stability. The shape memory effect is based on the transformation between martensitic and austenitic microstructure depending on the temperature of the actuators. The transformation temperatures in the range of 20°C to 100°C make NiTi SMA attractive for engineering applications. This paper investigates the technical use of NiTi SMA as actuators within a safety clutch. Safety clutches serve in power trains as torque limiting elements with the aim to prevent destruction of the working machine or the motor. Based on the concept of a friction clutch the conceptual design of the NiTi safety clutch is developed and followed by the design and manufacturing of a prototype. The activation of the NiTi actuators occurs as a result of the frictional heat at the friction pads when the torque limit is exceeded and the clutch slips. The actuators transform from martensitic to austenitic condition. Their stiffness increases so that the actuators are able to open the clutch. This leads to a complete collapse of the torque. During the cooling phase the transformation from austenite to martensite occurs and the NiTi actuators are deformed again. The friction pads are clamped with their original force and the clutch is able to transmit the demanded torque. The mechanical dimensioning of the actuator system is figured out as well as the measurement results of the analysis on the testing bench. The variation of the input parameters like torque and speed and the variation of the actuator system itself show possibilities and frontiers of this technology.
A State-Space Temporal Finite Element Approach for Stability Investigations of Delay Equations
Authors: Khasawneh Firas A. , Mann Brian P. , Patel Bhavin
Published: February 2010

This paper describes a new approach to examine the stability of delay differential equations that builds upon prior work using temporal finite element analysis. In contrast to previous analyses, which could only be applied to second order delay differential equations, the present manuscript develops an approach which can be applied to a broader class of systems — systems that may be written in the form of a state space model. A primary outcome from this work is a generalized framework to investigate the asymptotic stability of autonomous delay differential equations with a single time delay. Furthermore, this approach is shown to be applicable to time-periodic delay differential equations and equations that are piecewise continuous.
High Temperature Multi-Fuel Combustion-Powered Thermoelectric Auxiliary Power Unit
Authors: Headings Leon M. , Washington Gregory N. , Midlam-Mohler Shawn , Heremans Joseph P.
Published: February 2010

With rising worldwide energy demands, there is a growing need for technologies which are able to utilize alternative forms and sources of energy as well as to reduce consumption. While energy storage technologies are rapidly advancing, they are not yet capable of matching the energy densities of combustible fuels. The internal combustion engine (ICE), coupled with a generator, is the predominant method of converting this chemical energy into electrical energy, yet the mechanical nature of this system presents performance limitations. An alternative being developed here is a combustion-powered thermoelectric generator (C-TEG) to directly convert the heat released from combustion into electricity. The solid-state nature of thermoelectric (TE) devices provides the attractive inherent benefits of reliability, fuel flexibility, controllability, and potential for power densities exceeding that of ICE/generator systems. While low material and device efficiencies have thus far limited the use of TEGs to niche applications, recently developed materials have more than doubled the TE figure of merit, a material parameter strongly influencing efficiency. The rapid rate of TE material advancements merits the parallel development of device technologies. Opportunities for a durable, multi-fuel, high power density generator make C-TEGs potential candidates for many consumer, industrial, and military power applications including automotive auxiliary power. Within the automotive field, C-TEGs may be applied in hybrid-electric vehicles to provide power during engine cycling or in conjunction with a TE waste heat recovery system to provide power on demand. With sufficient improvements in efficiency, C-TEGs may be used in plug-in hybrid-electric vehicles where the C-TEG serves as the range extender in lieu of an ICE/generator system. Another application is to provide auxiliary power in commercial vehicles. In this research, a baseline prototype was first constructed with a conventional heat exchange configuration, a commercial bismuth telluride module (maximum 225 °C), and a novel fuel atomizer. This prototype was used to develop and validate a computer simulator, identify the greatest opportunities for improvement, validate the use of the fuel atomizer with diesel fuel for TE power generation, and provide a baseline performance with which to compare system improvements. Subsequent improvements were made to increase combustion efficiency, reduce thermal losses, and characterize the heat exchangers at 500 °C for accurate simulation of the system performance with high performance lead telluride modules. In addition, multiple fuels were tested to verify multi-fuel capability and performance, and the use of a Pt/Pd combustion catalyst was tested to quantify improvements in heat exchange effectiveness.
Electrical Tuning of Converse Magnetoelectric Effect in Piezo-Fiber/Metglas Laminates
Authors: Wu Tao , Chung Tien-Kan , Carman Gregory P.
Published: February 2010

The converse magnetoelectric effect of an asymmetric Piezo-fiber/Metglas bilayer laminate composite subjected to DC electric voltage and magnetic field biases is presented. The experimental results indicate that positive voltages applied to the Piezo-fiber layer produce large tensile strains in the Piezo-fiber layer with relatively small compressive strains in the Metglas layer. The influence of DC electric voltage bias on the converse magnetoelectric effect is studies and it is found that an optimal DC voltage bias exists to maximize the CME coefficient related to the “jumping” stress/strain in the Metglas. The optimum DC magnetic field bias is shift by applying DC voltage biases and the magnitude of converse magnetoelectric response can be electrically tuned.
Nonlinear Aeroelastic Behaviour of Compliant Airfoils
Authors: Thwapiah Ghalib Y. , Campanile Flavio L.
Published: February 2010

Since begin of the aviation and up to the present times, airfoils have always been built as rigid structures. They are designed to fly under their divergence speed in order to avoid static aeroelastic instabilities and the resulting large deformations which are not compatible with the typically low compliance of such airfoils. In recent years, research on airfoil morphing has generated interest in innovative ideas like the use of compliant systems, i.e. systems built to allow for large deformations without failure, in airfoil construction. Such systems can operate in the neighbourhood of divergence and take advantage of large aeroelastic servo-effects. This, in turn, could allow compact, advanced actuators to control the airfoil’s deformation and loads, and hence complement or even replace conventional flaps. In order to analyze and design such compliant, active aeroelastic structures a non-linear approach to static aeroelastic is needed, which takes into account the effect of large deformations on aerodynamics and structure. Such an analytical approach is presented in this paper and applied to a compliant passive airfoil as the preliminary step to the realisation of a piezoelectrically driven, active aeroelastic airfoil. Wind-tunnel test results are also presented and compared with the analytic prediction. The good agreement and the observed behaviour in the wind tunnel give confidence in the potential of this innovative idea.
Clapping Wing Nano Air Vehicle Using Piezoelectric T-Beam Actuators
Authors: Mateti Kiron , Kommepalli Hareesh K. R. , Tadigadapa Srinivas A. , Rahn Christopher D.
Published: February 2010

Clapping wing air vehicles are inspired by the Weis-Fogh clap and fling mechanism used by certain insects, where opposing wings almost touch during part of the flap cycle, spawning vortex structures that increase thrust. Current vehicles cannot be scaled to Nano Air Vehicle (NAV) dimensions because they use electromagnetic motors, gears, and linkages that are difficult to fabricate and have poor efficiency at the sub-millimeter scale. This paper develops a novel NAV that uses piezoelectric T-beam actuators that are monolithically fabricated and exhibit unimorph behavior. A hinge and lever wing mechanism amplifies the small actuator displacements to produce large wing motions. A four wing, clapping NAV is designed, fabricated, and experimentally shown to provide a wing stroke angle of approximately 35° at 1 Hz.
Endosomal Vaccine Delivery Through the Nastic Model
Authors: Freeman Eric , Weiland Lisa Mauck
Published: February 2010

Vaccine enters white blood cells through the process of endocytosis. In this process the cell extends and engulfs the surroundings, including a vaccine when present, for intake; the vaccine is then enclosed in an inclusion known as an endosome. With the foreign species (vaccine) encased, this endosome is then transported to the interior of the cell. While the endosome provides a convenient mode of transport for uptake, it also acts to destroy and break down its contents via a pH driven process before releasing it into the cell. It has been postulated that inducing endosome burst may be an effective way to affect the release of vaccine prior to the onset of degradation. The process of burst will be explored through adaptation of an existing active material (nastic) modeling methodology. The computational methodology employs coupling of transport kinetics to membrane elastic response. The study yields insight into the multi-mechanisms of burst, involved both in the specific case of vaccine delivery and applicable to the more general case of bio inspired materials development.
Development of a Proof-of-Concept Aircraft Smart Control System
Authors: Hutapea Parsaoran
Published: February 2010

Hutapea et al (Aircraft Engineering and Aerospace Technology: 80(4), 439–444, 2008) proposed an actuation system based on shape memory alloy springs for a wing flap of an aircraft. A continued research and development of these previously demonstrated smart flight control mechanisms was performed with the goal to develop a proof-of-concept shape memory alloy (SMA) actuation system, which utilizes SMA springs to control the six degrees of freedom of an aircraft. As a significant advancement to the overall actuation system, an air burst-cooling system was added to increase the cooling rate of the SMA springs by means of forced convection. A one-sixth scale proof-of-concept model was constructed to demonstrate and to verify the final actuation system design.
Optimal Control of Vertically Stroking Crew Seats Employing Magnetorheological Energy Absorbers
Authors: Singh Harinder J. , Choi Young-Tai , Wereley Norman M.
Published: February 2010

Nondimensional analyses of vertical stroking crew seats with adaptive nonlinear magnetorheological energy absorbers (MREA) and magnetorheological shock isolation (MRSI) were addressed in this study. Under consideration were single-degree-of-freedom vertically stroking seat systems consisting of a rigid occupant mass falling with prescribed initial impact velocity (sink rate). The governing equations of the vertical stroking crew seats were derived using nondimensional variables such as nondimensional stroke, velocity, acceleration and time constant, as well as nondimensional Bingham number (i.e., the ratio of MR yield force to viscous force). The critical Bingham number was defined as that Bingham number for which the available stroke was fully utilized and the seat reaches zero velocity at the end of stroke. This was done in order to maximize shock mitigation performance. Two cases were studied: (1) the MREA problem, or the case where no spring was employed in the suspension, so that the seat was used for a single shock event, (2) the MRSI problem, or the case where a spring was employed in the suspension, so that after the initial shock event, the suspension could be used for either vibration isolation or mitigation of subsequent shock events. Nondimensional displacement, velocity and acceleration were analyzed for MREA and MRSI vertical stroking crew seats for three different payload masses of 47, 77 and 97 kg corresponding to 5th percentile (%tile) female, 50th %tile and 95th %tile male, respectively, with initial impact velocities of 4, 5 and 6 m/s. An optimal control solution was derived for both the MREA and MRSI cases. The effects of payload mass and initial impact velocity on the optimal responses of the vertical stroking crew seats were analyzed for a feasible range of Bingham number based on a realistically constrained (in diameter and volume) MR damper design.
Modeling IPMC Material With Dynamic Surface Characteristics
Authors: Pugal Deivid , Aabloo Alvo , Kim Kwang J. , Jung Youngsoo
Published: February 2010

This paper presents the Finite Element Analysis (FEA) of an ionic polymer-metal composite (IPMC) material. The IPMC materials are known to bend when electric field is applied on the electrodes. The material also produces potential difference on the electrodes when is bent. Several authors have used the FEA to describe that fenomenon and rather precise basic Finite Element (FE) models already exist. Therefore the current study is mainly focused on the modeling of the electrodes of IPMC. The first goal of this research is to model the electric currents in the electrodes. The basis of the electric current calculations is the Ramo-Shockley theorem, which has been used in the other areas of physics to describe the currents in a circuit due to a charge movement in a media. We have used the theorem to calculate the current density in the continuous electrodes of IPMC due to the ion migration in the backbone polymer. Along the current densities we are able to calculate voltage on the electrode at a given time moment. The model is demonstrated to give some physically reasonable results. However, the model is rather complex and as the solution times are quite large, some possible optimizations have been considered as well. The second goal of this study is to include the dynamic resistance and capacitance of the electrodes in our model. Lot of research has been done to develop a physically reasonable capacitor-resistor model of an IPMC and the results have been promising. Furthermore, some authors have managed to develop partial differential equations (PDE) to describe the model. We try to include some simplified versions of those equations into our physical model. As the FE model for IPMC is nonlinear and gets complicated very fast when additional equations are added, the final sections of this paper briefly considers some novel optimization ideas in regard to modeling IPMC with FE method.
Theory of Compatible Domain Arrangements in Ferroelectric Thin Films
Authors: Tsou N. T. , Huber J. E.
Published: February 2010

Thin films of single crystal ferroelectric material are constrained by their substrate to a fixed state of macroscopic in-plane strain. Domain structures can form to minimize the overall energy of the system by matching the imposed strain conditions in an average sense. We study low-energy equilibrium states of ferroelectric thin films using the theory of domain compatibility. In a thin film with a given state of average strain, periodic laminate microstructures can be predicted or designed using compatibility theory and the condition that domain wall orientations parallel to the substrate are prohibited by the reduction to 2-dimensions. The theory is applied to [001], [011] and [111] oriented single crystal films of tetragonal ferroelectric materials. Compatible configurations are generated and the ability of such films to be poled by electric field is then explored.
Detection of Embedded Damage Growth by Analysing Its Structural Dynamic Response
Authors: Mehdizadeh Mohammad , Oruganti Krishna , Sabu John , Bannister Michael , Herszberg Israel
Published: February 2010

The primary focus of this paper is to report on the technique developed to extend a simulated damage site (such as a delamination) without inducing other extraneous damage modes. This was done in order to assess the suitability of curvature mode shape analyses in detecting damage types which are similar in type but different in severity or size. This paper highlights the use of vibration based testing on Carbon/Epoxy composite beams for damage detection. Such composites are commonly used in the aerospace and marine industry. The study comprises of testing carbon/epoxy composite beams with various embedded delaminations with a mechanical actuator and a Scanning Laser Vibrometer (SLV) as a sensor for recording the frequency response and the subsequent analyses of the acquired dynamic response based on Displacement and Curvature Mode Shapes. The paper also discusses the Finite Element Method (FEM)-based Analysis to validate the experimental results. In order to assess the effect of an increasing damage zone on a particular damage configuration, it was necessary to extend the damage without inflicting other damage types in the process. This paper reports on an innovative way of extending an existing delamination by a fatigue crack-growth technique. The ASTM E399-90 standard was used for the experiment and a carefully designed fatigue crack growth routine was implemented to advance the delamination in a controlled manner.
Design and Fabrication of a Variable Stiffness Link for Use in an Unmanned Air Vehicle
Authors: Boyerinas Brad M. , Clark William W. , Weiland Lisa M. , Joshi Shiv
Published: February 2010

A variety of methods have been introduced in recent years to implement morphing aircraft and other shape-changing structures, including high-force actuators that can elastically deform structural members, to stiffness-changing elements that more readily accommodate the deformations. This paper introduces a structural element of the latter type that can exist in two states: a rigid state that supports structural loads and locks the structure in place, and a soft state that enables deformation of the structure. The element itself is termed the “Smart Link” and is used in the folding mechanism of a morphing aircraft. The link is a composite made up of shape memory polymer (the softening material) and a backbone of shape memor alloy, which allows high deformation but ensures that the nominal shape is recovered upon return deformation. This paper presents the design requirements for the link in terms of the morphing aircraft application, and then presents the iterative design, fabrication, and testing process used to develop the Smart Link. Finally, results of testing of the link in the aircraft during wind tunnel tests are presented to show the pros and cons of its performance. In summary, the link met the mechanical requirements by performing multiple morphing cycles through the loads and deformation ranges (103 degrees of angle change) needed. The major drawback of the design is the response time necessary to transition the heat-activated material. Suggestions are given at the end of the paper for ways to improve the time response.
An Active Acoustic Metamaterial With Tunable Effective Density
Authors: Baz A.
Published: February 2010

Extensive efforts are being exerted to develop various types of acoustic metamaterials to effectively control the flow of acoustical energy through these materials. However, all these efforts are focused on passive metamaterials with fixed material properties. In this paper, the emphasis is placed on the development of a new class of one-dimensional acoustic metamaterials with tunable effective densities in an attempt to enable the adaptation to varying external environment. More importantly, the active metamaterials can be tailored to have increasing or decreasing variation of the material properties along and across the material volume. With such unique capabilities, physically realizable acoustic cloaks can be achieved and objects treated with these active metamaterials can become acoustically invisible. The theoretical analysis of this class of active acoustic metamaterials is presented and the theoretical predictions are determined for an array of air cavities separated by piezoelectric boundaries. These boundaries control the stiffness of the individual cavity and in turn its dynamical density. Various control strategies are considered to achieve different spectral and spatial control of the density of this class of acoustic metamaterials. A natural extension of this work is to include active control capabilities to tailor the bulk modulus distribution of the metamaterial in order to build practical configurations of acoustic cloaks.
Quantification of the Effectiveness of Various Conductive and Non-Conductive Epoxies as an Attachment Method for Small SMA Wires
Authors: Furst Stephen J. , Bumgarner David , Seelecke Stefan
Published: February 2010

The discovery of thermoelastic behavior in shape memory alloys (SMA) such as Nitinol enabled the conceptualization of many applications where actuators and sensors are embedded into a structural component. These so called “adaptive structures” can be extremely compact and energy efficient. SMA wires show characteristics similar to that of muscle fibers, and thus enable replication of an animal’s musculoskeletal system. Also, SMA wires are extremely attractive in the biomedical field where compact robotic elements can reduce the invasiveness of some surgical procedures. Unfortunately, widespread implementation of adaptive structures actuated by small SMA-wires in industry has been hindered by two significant challenges. First, SMA wires exhibit hysteretic behavior during heating and cooling that can be difficult to model without substantial computation. Second, attaching a small (∼50–100 μm diameter) SMA wire is extremely difficult because standard methods such as crimping are infeasible. The goal of this study is to quantify the effectiveness of using adhesives to hold a small SMA wire. A wide range of commercially available adhesives are tested under the conditions relevant to an application where SMA-wires are embedded directly within a structure. Epoxies are tested so that the adhesive will bond to both plastic and metallic elements. The experimental setup is designed to test the failure shear stress between an SMA wire and adhesive. A wire is encapsulated in a small drop of adhesive. Then the area of the wire that is exposed to the adhesive is measured under a microscope and the wire is pulled as a load cell measures the tensile load. The force that causes failure of the bond is recorded and used to calculate the failure shear stress between the adhesive and wire. The effects of using wires with different surface temperatures, and handling procedures (i.e. washing with acetone and handling with latex gloves) are also tested. Measurements under each set of parameters are repeated and quantitative results are obtained.
Multifunctional Multi-Scale Carbon-Fiber/Epoxy Matrix Composites Reinforced With Carbon Nanotubes
Authors: Thakre Piyush R. , Lagoudas Dimitris C.
Published: February 2010

In the present work, apart from developing a processing method for multi-scale laminates, characterization efforts are focused on finding longitudinal, transverse and in-plane shear modulus using flexure and in-plane shear testing of unidirectional, [0°]10, and multidirectional, [±45°]2s, laminates. A comparison of the above mentioned macroscale properties is presented for three types of composites, i.e., composites embedded with functionalized nanotubes, un-functionalized or pristine nanotubes and base composite without nanotubes. Classical laminate theory is used to model a representative laminate system. Transverse and longitudinal properties are presented and compared with experimental observations. Transmission and scanning electron microscopy is performed to study the nanotube dispersion and the morphology of fracture surfaces at different length scales.
Adipocyte-Derived Factors Potentiate Nutrient-Induced Production of Plasminogen Activator Inhibitor–1 by Macrophages
Authors: Kishore Preeti , Li Weijie , Tonelli Julia , Lee Do-Eun , Koppaka Sudha , Zhang Kehao , Lin Ying , Kehlenbrink Sylvia , Scherer Philipp E. , Hawkins Meredith
Published: February 2010

In response to free fatty acids and factors from fat cells, macrophages within the fat tissue of obese individuals release a hormone that contributes to atherosclerosis and insulin resistance.
Development of Personalized Tumor Biomarkers Using Massively Parallel Sequencing
Authors: Leary Rebecca J. , Kinde Isaac , Diehl Frank , Schmidt Kerstin , Clouser Chris , Duncan Cisilya , Antipova Alena , Lee Clarence , McKernan Kevin , De La Vega Francisco M. , Kinzler Kenneth W. , Vogelstein Bert , Diaz Luis A. , Velculescu Victor E.
Published: February 2010

Rapid detection of specific aberrant rearrangements in tumors from individuals yields a well-poised technological advance toward personalized oncology.
Let There Be Light: Next-Generation Artificial Corneas
Authors: Ng Kenneth W.
Published: February 2010

An artificial cornea that restores both innervation and optical function in guinea pigs may one day eliminate the shortage of donor corneas, making routine corneal transplant possible.
Characterization of a Novel LysM Domain from
Lactobacillus fermentum
Bacteriophage Endolysin and Its Use as an Anchor To Display Heterologous Proteins on the Surfaces of Lactic Acid Bacteria
Authors: Hu Shumin , Kong Jian , Kong Wentao , Guo Tingting , Ji Mingjie
Published: February 2010

The endolysin Lyb5, from
Lactobacillus fermentum
temperate bacteriophage φPYB5, showed a broad lytic spectrum against Gram-positive as well as Gram-negative bacteria. Sequence analysis revealed that the C terminus of the endolysin Lyb5 (Ly5C) contained three putative lysin motif (LysM) repeat regions, implying that Ly5C was involved in bacterial cell wall binding. To investigate the potential of Ly5C for surface display, green fluorescent protein (GFP) was fused to Ly5C at its N or C terminus and the resulting fusion proteins were expressed in
Escherichia coli
. After being mixed with various cells
in vitro
, GFP was successfully displayed on the surfaces of
Lactococcus lactis
,
Lactobacillus casei
,
Lb. brevis
,
Lb. plantarum
,
Lb. fermentum
,
Lb. delbrueckii
,
Lb. helveticus
, and
Streptococcus thermophilus
cells. Increases in the fluorescence intensities of chemically pretreated
L. lactis
and
Lb. casei
cells compared to those of nonpretreated cells suggested that the peptidoglycan was the binding ligand for Ly5C. Moreover, the pH and concentration of sodium chloride were optimized to enhance the binding capacity of GFP-Ly5C, and high-intensity fluorescence of cells was observed under optimal conditions. All results suggested that Ly5C was a novel anchor for constructing a surface display system for lactic acid bacteria (LAB). To demonstrate the applicability of the Ly5C-mediated surface display system, β-galactosidase (β-Gal) from
Paenibacillus
sp. strain K1, replacing GFP, was functionally displayed on the surfaces of LAB cells via Ly5C. The success in surface display of GFP and β-Gal opened up the feasibility of employing the cell wall anchor of bacteriophage endolysin for surface display in LAB.
Immobilization of Cr(VI) and Its Reduction to Cr(III) Phosphate by Granular Biofilms Comprising a Mixture of Microbes
Authors: Nancharaiah Y. V. , Dodge C. , Venugopalan V. P. , Narasimhan S. V. , Francis A. J.
Published: February 2010

We assessed the potential of mixed microbial consortia, in the form of granular biofilms, to reduce chromate and remove it from synthetic minimal medium. In batch experiments, acetate-fed granular biofilms incubated aerobically reduced 0.2 mM Cr(VI) from a minimal medium at 0.15 mM day
−1
g
−1
, with reduction of 0.17 mM day
−1
g
−1
under anaerobic conditions. There was negligible removal of Cr(VI) (i) without granular biofilms, (ii) with lyophilized granular biofilms, and (iii) with granules in the absence of an electron donor. Analyses by X-ray absorption near edge spectroscopy (XANES) of the granular biofilms revealed the conversion of soluble Cr(VI) to Cr(III). Extended X-ray absorption fine-structure (EXAFS) analysis of the Cr-laden granular biofilms demonstrated similarity to Cr(III) phosphate, indicating that Cr(III) was immobilized with phosphate on the biomass subsequent to microbial reduction. The sustained reduction of Cr(VI) by granular biofilms was confirmed in fed-batch experiments. Our study demonstrates the promise of granular-biofilm-based systems in treating Cr(VI)-containing effluents and wastewater.
Impact of Endochitinase-Transformed White Spruce on Soil Fungal Biomass and Ectendomycorrhizal Symbiosis
Authors: Stefani Franck O. P. , Tanguay Philippe , Pelletier Gervais , Piché Yves , Hamelin Richard C.
Published: February 2010

The impact of transgenic white spruce [Picea glauca(Moench) Voss] containing the endochitinase gene (ech42) on soil fungal biomass and on the ectendomycorrhizal fungiWilcoxinaspp. was tested using a greenhouse trial. The measured level of endochitinase in roots of transgenic white spruce was up to 10 times higher than that in roots of nontransformed white spruce. The level of endochitinase in root exudates of three of fourech42-transformed lines was significantly greater than that in controls. Analysis soil ergosterol showed that the amount of fungal biomass in soil samples from control white spruce was slightly larger than that in soil samples fromech42-transformed white spruce. Nevertheless, the difference was not statistically significant. The rates of mycorrhizal colonization of transformed lines and controls were similar. Sequencing the internal transcribed spacer rRNA region revealed that the root tips were colonized by the ectendomycorrhizal fungiWilcoxinaspp. and the dark septate endophytePhialocephala fortinii. Colonization of root tips byWilcoxinaspp. was monitored by real-time PCR to quantify the fungus present during the development of ectendomycorrhizal symbiosis inech42-transformed and control lines. The numbers ofWilcoxinamolecules in the transformed lines and the controls were not significantly different (P> 0.05, as determined by analysis of covariance), indicating that in spite of higher levels of endochitinase expression, mycorrhization was not inhibited. Our results indicate that the higher levels of chitinolytic activity in root exudates and root tissues fromech42-transformed lines did not alter the soil fungal biomass or the development of ectendomycorrhizal symbiosis involvingWilcoxinaspp.
New Efficient Recombinant Expression System To Engineer
Candida antarctica
Lipase B
Authors: Emond Stéphane , Montanier Cédric , Nicaud Jean-Marc , Marty Alain , Monsan Pierre , André Isabelle , Remaud-Siméon Magali
Published: February 2010

Here, we report the use of
Yarrowia lipolytica
as a versatile expression host for developing protein engineering approaches to modify the properties of
Candida antarctica
lipase B. A reliable screening protocol was defined and validated using a saturation mutagenesis library, yielding mutants displaying higher catalytic efficiencies than the wild-type enzyme.
Interaction of an Essential
Escherichia coli
GTPase, Der, with the 50S Ribosome via the KH-Like Domain
Authors: Hwang Jihwan , Inouye Masayori
Published: February 2010

Der, an essential
Escherichia coli
tandem GTPase, has been implicated in 50S subunit biogenesis. The
rrmJ
gene encodes a methyltransferase that modifies the U2552 residue of 23S rRNA, and its deletion causes a severe growth defect. Peculiarly, overexpression of Der suppresses growth impairment. In this study, using an
rrmJ
-deletion strain, we demonstrated that two GTPase domains of Der regulate its association with 50S subunit via the KH-like domain. We also identified a region of Der that is critical for its specific interaction with 50S subunit.
A DNA-Binding Peroxiredoxin of
Coxiella burnetii
Is Involved in Countering Oxidative Stress during Exponential-Phase Growth
Authors: Hicks Linda D. , Raghavan Rahul , Battisti James M. , Minnick Michael F.
Published: February 2010

Coxiella burnetii
is a Gram-negative, obligate intracellular bacterial pathogen that resides within the harsh, acidic confines of a lysosome-like compartment of the host cell that is termed a parasitophorous vacuole. In this study, we characterized a thiol-specific peroxidase of
C. burnetii
that belongs to the atypical 2-cysteine subfamily of peroxiredoxins, commonly referred to as bacterioferritin comigratory proteins (BCPs).
Coxiella
BCP was initially identified as a potential DNA-binding protein by two-dimensional Southwestern (SW) blots of the pathogen's proteome, probed with biotinylated
C. burnetii
genomic DNA. Confirmation of the identity of the DNA-binding protein as BCP (CBU_0963) was established by matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry (MALDI-TOF/TOF MS). Recombinant
Coxiella
BCP (rBCP) was generated, and its DNA binding was demonstrated by two independent methods, including SW blotting and electrophoretic mobility shift assays (EMSAs). rBCP also demonstrated peroxidase activity
in vitro
that required thioredoxin-thioredoxin reductase (Trx-TrxR). Both the DNA-binding and peroxidase activities of rBCP were lost upon heat denaturation (100°C, 10 min). Functional expression of
Coxiella bcp
was demonstrated by
trans
-complementation of an
Escherichia coli bcp
mutant, as evidenced by the strain's ability to grow in an oxidative-stress growth medium containing
tert
-butyl hydroperoxide to levels that were indistinguishable from, or significantly greater than, those observed with its wild-type parental strain and significantly greater than
bcp
mutant levels (
P
< 0.05). rBCP was also found to protect supercoiled plasmid DNA from oxidative damage (i.e., nicking)
in vitro
. Maximal expression of the
bcp
gene coincided with the pathogen's early (day 2 to 3) exponential-growth phase in an experiment involving synchronized infection of an epithelial (Vero) host cell line. Taken as a whole, the results show that
Coxiella
BCP binds DNA and likely serves to detoxify endogenous hydroperoxide byproducts of
Coxiella
's metabolism during intracellular replication.
Biochemical Dissection of the ATPase TraB, the VirB4 Homologue of theEscherichia colipKM101 Conjugation Machinery
Authors: Durand Eric , Oomen Clasien , Waksman Gabriel
Published: February 2010

Type IV secretion (T4S) systems are involved in several secretion processes, including secretion of virulence factors, such as toxins or transforming molecules, or bacterial conjugation whereby two mating bacteria exchange genetic material. T4S systems are generally composed of 12 protein components, three of which, termed VirB4, VirB11, and VirD4, are ATPases. VirB4 is the largest protein of the T4S system, is known to play a central role, and interacts with many other T4S system proteins. In this study, we have biochemically characterized the protein TraB, a VirB4 homologue from the pKM101 conjugation T4S system. We demonstrated that TraB is a modular protein, composed of two domains, both able to bind DNA in a non-sequence-specific manner. Surprisingly, both TraB N- and C-terminal domains can bind ATP, revealing a new degenerated nucleotide-binding site in the TraB N-terminal domain. TraB purified from the membrane forms stable dimers and is unable to hydrolyze ATP while, when purified from the soluble fraction, TraB can form hexamers capable of hydrolyzing ATP. Remarkably, both the N- and C-terminal domains display ATP-hydrolyzing activity. These properties define a new class of VirB4 proteins.
Non-ideal behaviour of binary liquid mixtures and different approaches to calculate ideal expansibility
Authors: Kumar Harsh
Published: February 2010

Densities for binary mixtures of cyclopentane with 1-propanol, 1-pentanol, and 1-heptanol over the whole composition range have been measured at temperature 318.15 K. From these densities, excess molar volumes were calculated. All the experimental excess molar volumes were fitted to Redlich–Kister equation and were analyzed with the help of Prigogine–Flory–Patterson theory. Also isobaric expansibilities and their excess counterparts were calculated. Further different approaches were analysed for calculating ideal expansibilities.
QUANTUM MECHANICAL TREATMENT OF THE ELECTRON–BOSON INTERACTION VIEWED AS A COUPLING THROUGH FLUX LINES: POLARONS
Authors: DOLOCAN VOICU , DOLOCAN ANDREI , DOLOCAN VOICU-OCTAVIAN
Published: February 2010

By using a Hamiltonian based on the coupling through flux lines between electrons and bosons, we have calculated the electron–phonon interaction energy and the electron–electron interaction energy via bosons in an isotropic medium and in a lattice. We have calculated the correction energy to the electron energy due to the electron interaction with acoustic phonons and we have found that in covalent crystals it is of the order of 0.1 eV. Also, we have presented the results for the weak coupling and strong coupling polarons in ionic crystals. By applying this Hamiltonian to electron–electron interaction via mass less bosons we have found an equivalent expression for Coulomb's law, αℏc/R, where α is the fine structure constant.