bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Bend-Twist PZT Actuator for Centimeter-Scale Flapping Wing Micro-Air Vehicle
Authors: Hall Asha J. , Riddick Jaret C.
Published: February 2012

The present study focuses on development of a flapping wing micro-air vehicle (FWMAV) that employs a piezoelectric actuator to drive the leading edge of the wing. An analysis of insect flight indicates that in addition to the bending excitation (flapping), simultaneous excitation of the twisting degree-of-freedom is required to adequately manipulate the control surface. A functionally-modified piezoelectric bimorph composed of Pb(Zr0.55Ti0.45)O3 (PZT) is being used to produce two degree-of-freedom motion, namely the flapping and twisting facilitated by an off-axis layer of piezoelectric segments affixed to the top surface of a traditional bimorph actuator. The modification of the top surface of a traditional PZT bimorph actuator introduces active bend-twist coupling to the flexural response of the resulting layered PZT. This paper presents analytical and experimental investigation of functionally-modified bimorph designs intended for active bend-twist actuation of cm-scale flapping wing devices.
Using Multiscale Carbon Fiber/Carbon Nanotubes Composites for Damping Applications
Authors: Tehrani Mehran , Safdari Masoud , Case Scott W. , Al-Haik Marwan S.
Published: February 2012

A novel technique to grow carbon nanotubes (CNTs) on the surface of carbon fibers in a controlled fashion using simple lab set up is developed. Growing CNTs on the surface of carbon fibers will eliminate the problem of dispersion of CNTs in polymeric matrices. The employed synthesis technique retains the attractive feature of uniform distribution of the grown CNTs, low temperature of CNTs’ formation, i.e. 550 °C, via cheap and safe synthesis setup and catalysts. A protective thermal shield of thin ceramic layer and subsequently nickel catalytic particles are deposited on the surface of the carbon fiber yarns using magnetron sputtering. A simple tube furnace setup utilizing nitrogen, hydrogen and ethylene (C2H4) were used to grow CNTs on the carbon fiber yarns. Scanning electron microscopy revealed a uniform areal growth over the carbon fibers where the catalytic particles had been sputtered. The structure of the grown multiwall carbon nanotubes was characterized with the aid of transmission electron microscopy (TEM). Dynamical mechanical analysis (DMA) was employed to measure the loss and storage moduli of the hybrid composite together with the reference raw carbon fiber composite and the composite for which only ceramic and nickel substrates had been deposited on. The DMA tests were conducted over a frequency range of 1–40 Hz. Although the storage modulus remained almost unchanged over the frequency range for all samples, the loss modulus showed a frequency dependent behavior. The hybrid composite obtained the highest loss modulus among other samples with an average increase of approximately 25% and 55% compared to composites of the raw and ceramic/nickel coated carbon fibers, respectively. This improvement occurred while the average storage modulus of the hybrid composite declined by almost 9% and 15% compared to the composites of reference and ceramic/nickel coated samples, respectively. The ultimate strength and elastic moduli of the samples were measured using standard ASTM tensile test. Results of this study show that while the addition of the ceramic layer protects the fibers from mechanical degradation it abolishes the mechanisms by which the composite dissipates energy. On the other hand, with almost no compromise in weight, the hybrid composites are good potential candidate for damping applications. Furthermore, the addition of CNTs could contribute to improving other mechanical, electrical and thermal properties of the hybrid composite.
Damage Localization in a Stiffened Composite Panel Using a Lamb Wave Based Tomography Approach
Authors: Vizzini Anthony J. , Liu Yingtao , Chattopadhyay Aditi
Published: February 2012

In structural health monitoring (SHM) of aerospace components, such as stiffened panels, detection and localization of damage is an important issue. This paper presents a methodology for determining the existence and location of low velocity impact damage in a stiffened composite panel. Using a matching pursuit decomposition algorithm, converted modes due to damage were extracted in the time-frequency domain. The energy of the converted mode was then used in conjunction with a probabilistic tomography approach that was able to localize the damage with a high level of accuracy. The results obtained confirm the ability of this approach to detect and localize damage in complex composite structures.
Design of a Bio-Inspired Smart Ear Prototype
Authors: Mu¨ller Rolf , Meymand Sajjad Z. , Pannala Mittu , Reddy Ojili Praveen Kumar , Gao Li
Published: February 2012

The outer ears (pinnae) of many bat species are smart structures that undergo non-rigid deformations controlled through an intricate muscular actuation system. It is hypothesized that such non-rigid changes in the physical shape of the pinnae provide a substrate for adaption of the spatial sensitivity (reception beampattern) of the animals’ biosonar system on a short time scale. In the research presented here, a simplified biomimetic baffle shape was developed to investigate the functional properties of non-rigidly deforming baffles. This prototype had the shape of an obliquely truncated cone that was augmented with local shape features that aided in achieving a biomimetic deformation pattern and may also have direct acoustic effects on the device beampattern. The prototype was manufactured from a thin sheet of rubber and actuated parsimoniously through a single linear actuator. Despite its comparative simplicity, the prototype device was able to reproduce the deformation pattern seen in the ears of horseshoe bats qualitatively. Biomimetic baffle deformations resulted in profound, qualitative, and quantitative changes to the beampattern. Future research will investigate how the time-variant beampatterns relate to the specifics of the deformation patterns and how they could be controlled and used in an engineering context.
Behavior of a Compressible Magnetorheological Fluid Damper at High Temperatures
Authors: McKee Micheal , Wang Xiaojie , Gordaninejad Faramarz
Published: February 2012

This study focuses on the effect of temperature on the performance of compressible magnetorheological fluid dampers (CMRDs). In addition to change of properties in the presence of a magnetic field, magnetorheological fluids (MRFs) are temperature-dependent materials that their compressibility and rheological properties change with temperature, as well. A theoretical model that incorporates the temperature-dependent properties of MRF is developed to predict the behavior of a CMRD. An experimental study is also conducted using an annular flow CMRD with varying temperatures, motion frequencies, and magnetic fields. The experimental results are used to verify the theoretical model. The effect of temperature on the MRF properties, such as, the bulk modulus, yield stress and viscosity, are explored. It is found that the shear yield stress of the MRF remains unchanged within the testing range while both the plastic viscosity, using the Bingham plastic model, and the bulk modulus of the MRF decrease as temperature increases. In addition, it is observed that both the stiffness and the energy dissipation decrease with an increase in temperature.
Exact Solution for Bending of Shape Memory Alloy Superelastic Beams
Authors: Eshghinejad Ahmadreza , Elahinia Mohammad
Published: February 2012

Bending is a common mode of application and operation of shape memory alloys (SMA). So far the coupled thermomechanical behavior of these alloys have been modeled with numerical methods such as finite element. The issue in developing exact solutions for a SMA beam in bending is because of the distributed and hysteric stress-strain profile. In this paper an analytical approach is developed to find the exact solution for the displacement due to the applied force on the SMA superelastic beam. The approach is based on the assumption of linear distribution of strain along the height of a cross section in the beam. The solution is validated by experimental data and the results of the solution for a superelastic beams for different cases are illustrated.
Electrical Properties of Carbon Nanomaterial-Based Structural-Energy Storage Devices
Authors: Rivera Monica , Cole Daniel P. , Bundy Mark
Published: February 2012

A major challenge in micro unmanned vehicle and, in particular, micro aerial vehicle development stems from the lack of suitable energy storage devices. Demanding voltage and power requirements and stringent size and weight constraints significantly limit the number and type of batteries that can be housed in the micro vehicle structures. As a result, vehicle payloads and endurance times are significantly compromised. One approach to solving this issue would be to develop multifunctional energy storage devices that are capable of supplying energy to the vehicle while bearing some of the vehicle’s structural loads. In doing so, the amount of mass available for payload and/or additional energy storage devices can be increased. Recently, researchers have demonstrated the ability to produce lightweight, flexible batteries and supercapacitors based on carbon nanotubes and graphene. Due to their low mass, small size, and energy storing potential, carbon nanomaterial-based energy storage devices are excellent candidates for use in micro vehicle applications. However, due to the rapid pace in which the nanoscience field is advancing, there is limited information on how different materials, processing techniques, and device architectures influence the electrical properties of the device under investigation. In this study, we will systematically review these variables in an effort to discover how the materials and structure of the electrode and separator might be tailored to achieve both the desired material properties and the highest energy density per device weight and volume.
Modeling the Torsional Behavior of Superelastic Wires
Authors: Karbaschi Zohreh , Elahinia Mohammad
Published: February 2012

Torsional behavior of shape memory alloys can be employed in different biomedical applications. The goal of this paper is to investigate the behavior of these alloys under torsional loading conditions. To this end a torsional model is developed in MATLAB, in which a uniaxial model is extended to predict the torque-angle behavior of superelastic wires/rods. Tensile and torsional testing are performed on NiTi wires to determine martial properties and to verify this model. The material properties are determined based on ASTM standards. The effect of different parameters such as lengths and radii on the torque-angle behavior are investigated with the model. Moreover, the effect of temperature on the torsional behavior of SMA wires are presented.
Hydroelastic Power and Thrust Generation Using Macro-Fiber Composite Piezoelectrics
Authors: Erturk Alper , Delporte Ghislain
Published: February 2012

Flexible piezoelectrics offer several advantages to use in energy harvesting and biomimetic locomotion. These advantages include ease of application, high power density, silent and effective operation over a range of frequencies as well as light weight. Piezoelectric materials exhibit the well-known direct and converse piezoelectric effects. The direct piezoelectric effect has received growing attention for low-power generation to use in wireless electronic applications while the converse piezoelectric effect constitutes an alternative to replace the conventional actuators used in biomimetic locomotion. In this paper, underwater thrust and electricity generation are investigated experimentally by focusing on biomimetic structures with macro-fiber composite piezoelectrics. Fish-like bimorph configurations with and without a passive caudal fin (tail) are fabricated and compared. The favorable effect of having a passive caudal fin on the frequency bandwidth is reported. The presence of a passive caudal fin is observed to bring the second bending mode close to the first one, yielding a wideband behavior in thrust generation. The same smart fish configuration is tested for underwater piezoelectric power generation in response to harmonic excitation from its head. Hydrodynamic loads resulting from base excitation yield considerably larger power output as compared to in-air base excitation at the same acceleration amplitude. This work also discusses the feasibility of thrust generation using the harvested energy toward enabling self-powered swimmer systems.
Modeling and Simulation of the Mechanical Response of Martensitic Shape Memory Alloys
Authors: Zaki Wael
Published: February 2012

The process of detwinning of martensite in shape memory alloys involves the deformation of the crystalline lattice of the material by twin boundary motion. The amount of maximum deformation that can be achieved this way is known to saturate at some point, beyond which further loading will eventually lead to permanent deformation of the material. We present an algorithm for the simulation of martensite reorientation in shape memory materials subjected to multiaxial loading that may exceed the saturation threshold. If the applied load is still nonproportional beyond this threshold, the reorientation strain tensor may continue to evolve while its magnitude remains constant. Such evolution can be simulated using a simple strain-based criterion. The complete process of martensite reorientation can thus be modeled using a set of two yield functions, the first of which is stress-based and governs the detwinning process prior to saturation, and the second is strain-based and governs the reorientation of variants at maximum equivalent reorientation strain. The model is implemented in a numerical analysis code. For this purpose, the evolution equations are solved implicitly using a Newton-Raphson scheme and the tangent stiffness matrix of the material is determined using a combination of analytical and numerical techniques.
Stability and Hopf Bifurcation of Impact Dynamics Considering Delay in a Semi-Active Energy Absorbing Suspension System
Authors: Dong Xiaomin , Hu Wei , Yu Miao , Wereley Norman M.
Published: February 2012

In a crash event, such as the crash of an aircraft or the collision of two ground vehicles, the impact dynamics are a function of the impact velocity and payload mass. A typical bumper system on a ground vehicle has passive viscous energy absorbers (PVEAs) that are optimally designed for a specific impact velocity and payload, so that off-design performance may be suboptimal, and may even be unacceptable for large perturbations in sink rate and payload mass from the designed values. This is because the load-stroke profile of the energy absorbing suspension system (EASS) is passive in that spring stiffness and damping of the energy absorbers is fixed. Therefore, in this study, the PVEA in an EASS is replaced by an active or semi-active energy absorber (SAEA), and the effects of time delay in achieving controllable semi-active damping is analyzed in the context of impact dynamics. To accomplish this, a three degree-of-freedom dynamic model of an EASS is presented, and the effect of the time delay in commanding the controllable force of the EA is analyzed. The asymptotic stability and Hopf bifurcation of the trivial steady state response are analyzed for a range of time delay. A technique to stabilize the impact dynamic is developed, and it is shown that the impact dynamics can be stabilized using appropriate feedback control.
Exact Solution for Pure Torsion of SMA Curved Bars With Application to Analyzing SMA Helical Springs
Authors: Mirzaeifar Reza , DesRoches Reginald , Yavari Arash
Published: February 2012

In this paper, the pure torsion of SMA curved bars with circular cross sections is studied analytically. First, a three-dimensional phenomenological macroscopic constitutive model for polycrystalline SMAs is reduced to the one-dimensional pure shear case and then a closed-form solution for torsional response of SMA curved bars in loading and unloading is obtained. The effect of a direct shear force in the cross section is also considered in the solution which enables the formulation for analyzing SMA helical springs. Several case studies are presented in order to investigate the accuracy of the proposed method in predicting the torsional response of SMA curved bars, the stress distributions, and analyzing SMA helical springs.
Massively Parallel Simulations of Chain Formation and Restructuring Dynamics in a Magnetorheological Fluid
Authors: Sherman Steven G. , Paley Derek A. , Wereley Norman M.
Published: February 2012

Magnetorheological fluids consist of micron sized iron particles mixed in a carrier fluid, and are commonly used in adaptive dampers. Current simulations of MR fluids have been limited to thousands of particle and have been unable to simulate a a practical fluid volume (∼ mm3) with a high solids loading (∼ 25 vol %). In this paper, we use NVIDIA’s CUDA programming environment to simulate over one million particles. Using these simulations, we can dynamically simulate chain formation and restructuring in a practical millimeter scale fluid volume with realistic solids loading. The chain structures can be characterized in terms of extent and number, as well as obtaining physical metrics such as yield stress.
An Automated Testing Assembly for Characterizing Stiffness of an Ankle Foot Orthosis
Authors: Bhadane Minal Y. , Armstrong Charles , Hefzy Mohamed Samir , Elahinia Mohammad H.
Published: February 2012

An ankle foot orthosis (AFO) is a device that provides a controlled force to compensate for the muscle deficiencies in the ankle and helps normalize the gait of the patient. Evidence has indicated that there exists an optimal match correlating the patient’s gait related problems and the AFO stiffness. AFO ankle stiffness is measured by the moment around the ankle joint exerted by the AFO per degree of ankle joint rotation. To date, several testing devices and procedures have been developed to assess the stiffness characteristics of AFOs. Most of the devices are manually driven and may not exactly replicate human leg motion. Objective of developing an automated testing assembly is to identify stiffness characteristics of passive AFOs so as to develop an active AFO with shape memory alloy. We have developed an assembly using aluminum T-slotted profiles, single flange linear bearings, and living hinges from 80/20 Inc. Angle measurement was done by mounting Digital Protractor on the shank segment. The whole assembly was mounted on BOSE ElectroForce 3330 test instrument. dSPACE hardware-in-the-loop solution was used for real time data capture of force and angle sensor output. After assessing the characteristics of passive AFO we incorporated SMA wire in the AFO. Similar tests were conducted to evaluate effect of SMA wires on the overall stiffness of an AFO. The results confirm that SMA wires provide stiffness variation such a way that AAFO can be developed to achieve stiffness variation close to normal ankle stiffness.
Effects of Temperature Boundary Conditions on SMA Actuator Performance Using a Fully Coupled Thermomechanical Model
Authors: Lewis Nicole , Seelecke Stefan
Published: February 2012

The effects of temperature boundary conditions and the resulting performance of an SMA actuator were studied for an SMA wire coupled with a stiff spring. The wire was actuated via joule heating under both adiabatic and isothermal boundary conditions. The resulting temperature, phase fraction, strain and stress profiles along the wire were studied together with the wire tip displacement. The simulations were conducted using the finite element program ABAQUS, and a fully thermo-mechanically coupled shape memory alloy (SMA) actuator model was used to simulate the behavior. ABAQUS’s user material (UMAT) feature was utilized to model the SMA wire using a mesoscopic free energy model [1] in order to accurately describe the thermomechanically coupled actuator behavior. The results from the simulations highlighted the differences between homogeneous and inhomogeneous profiles, and a 34% difference in actuation stroke between the two cases was observed.
Development of a Shape Memory Alloy Heat Engine Through Experiment and Modeling
Authors: Keefe Andrew C. , McKnight Geoffrey P. , Herrera Guillermo A. , Bedegi P. Anthony , Churchill Christopher B. , Browne Alan L. , Brown Jeff
Published: February 2012

Few technologies can produce meaningful power from low temperature waste heat sources below 250°C, particularly on a per-mass basis. Since the 1970’s energy crisis, NiTi shape memory alloy (SMA) and associated thermal engines have been considered a viable heat-to-power transducer but were not adopted due to previously poor material quality, low supply, design complexity, and cost. Decades of subsequent material development, research, and commercialization have resulted in the availability of consistently high-quality, well-characterized, low cost alloys and a renewed interest in SMA as a waste heat energy recovery technology. The Lightweight Thermal Energy Recovery System (LighTERS) is an ongoing ARPA-E funded collaboration between General Motors Company, HRL Laboratories, Dynalloy, Inc., and the University of Michigan. In this paper we will present initial results from investigations of a closed loop SMA thermal engine (a refinement of the Dr. Johnson design) using a helical coil element and forced-air heat exchange. This engine generates mechanical power by continuously pulling itself through separate hot and cold air streams using the shape memory phase transformation to alternately expand and contract at frequencies between 0.25 and 2 Hz. This work cycle occurs continuously along the length of the coil loop and produces steady state power against an external moment. We present engine features and the thermal envelope that resulted in devices achieving between 0.1 and 0.5 W/g of shape memory alloy material using only forced air heat exchangers and room temperature cooling.
Fabrication and Characterization of Gallium Nitride Unimorphs for Optical MEMS Applications
Authors: Ramesh Prashanth , Washington Gregory N. , Krishnamoorthy Sriram , Rajan Siddharth
Published: February 2012

The research outlined in this paper describes part of a larger effort to develop a novel branch of next-generation materials systems called Distributed Intelligent Materials Systems (DIMS) which incorporate actuation, sensing, electronics and communications modules as inherent parts of the material structure. Newer semiconductor materials that are under active research in the field of microelectronics are very well suited for such material systems. Gallium Nitride (GaN), a smart material, is pursued as a candidate material for such a system with a piezoelectrically actuated, optical microswitch being developed as the first prototypical device. This paper covers the unique electromechanical properties of GaN highlighting its differences from other piezoelectrics, the device configuration used to realize the switching device, followed by a description of and the progress made in using a nascent fabrication technology (PhotoElectroChemical Etching) used to realize the 3-dimensional device structure. Finally a low-cost, laser-based, non-contact approach to testing and characterizing the microscale device is described.
Service Systems for Shape Memory Technology
Authors: Langbein Sven , Meier Horst , Czechowicz Alexander
Published: February 2012

Shape memory alloys (SMA) are well-known for their ability to transform into an imprinted shape by means of thermal activation (pseudoplasticity) or after a mechanical deformation (pseudoelasticity). The thermal effects can be used in a wide range of industrial applications like valves, unlocking devices or comfort applications in the field of automotive mechatronics. While there are many ideas concerning shape memory actuators, only few thoughts have been spent on service applications around these unique actuators. At present, product-related services are usually considered as an add-on to the actual product. But in future, industrialized countries are subject to a structural change toward service societies. For this reason, new concepts and methods which enable the companies to design the potential services in an optimal way are necessary already during the development of a product. This is a paradigm shift from the separated consideration of products and services to a new product understanding consisting of integrated products and services. In the case of shape memory technology, recycling processes present an interesting field for such integrated services. Starting with general ideas towards recycling concepts for and with shape memory components, this paper focuses on refresh-annealing as an example of an interesting recycling process. Finally, the paper is summed up by an outlook on future works on development methods for generic shape memory actuators and their service systems. The aim of this study is to show the possibilities and the importance of services in the field of shape memory technology. As a result, new applications and markets for SMA can be developed.
Effect of Lamb Wave Excitation Frequency on Detection of Delamination in Composite Plates
Authors: Kim Inho , Jha Ratneshwar
Published: February 2012

This paper presents experimental investigations of the effect of Lamb wave excitation frequency on detection of a given delamination in composite plates. Typical aerospace type composite plates are used and integrated piezoelectric transducers function as both actuator and sensor. Also, a scanning Laser Doppler Vibrometer (LDV) is used for preliminary sensing of structural responses when excited by a single PZT actuator. Results in time domain are quantified by a damage index calculation based on modified L2 error norm. Phase difference calculations based on complex continuous wavelet transform (CWT) and Hilbert-Huang transform (HHT) are presented. Experimental results show a significant effect of incident Lamb waves on delamination signature.
Model of the Electro-Dynamical Field Distribution for an Optimized Electrode Design of DEAP Transducers
Authors: Graf Christian , Maas Ju¨rgen
Published: February 2012

Dielectric Electroactive Polymers belong to a new class of smart materials, whose functional principle is based on electrostatic forces. They can either be used as actuators to provide considerable stretch ratios or as generators to convert mechanical strain energy into electrical energy by use of an initial amount of energy. Since the polymer material and also the covering compliant electrodes show non-ideal electrical properties, like finite resistivity and conductivity respectively, design rules have to be derived, in order to optimize the devices. The electrode conductivity in connection with the polymer resistivity causes a voltage drop along the electrode surface, resulting in a reduced actuation strain or energy conversion. To minimize its parasitic effects, the influence of this effect is studied for the transient and steady state behavior first in order to derive rules for the optimal placement of electrode contacts secondly.
Pathways Into Corrosion Related Naval Applications
Authors: DeGiorgi Virginia G.
Published: February 2012

The cost of corrosion to the US military is huge. In 2006–2007 the US Navy spent $3.2 Billion on corrosion related maintenance on ships alone. Additional funds were expended maintaining US Navy aircraft, helicopters and land vehicles. The cost of corrosion must be controlled. It is apparent that extraordinary cost reductions are needed to bring the problem under control. In order to achieve such dramatic improvements changes from conventional methods of construction, inspection and monitoring are necessary. There are ample opportunities for active material technologies if the researcher understands the fundamental corrosion problem. In this paper the author outlines information on US Navy corrosion concerns including examples of recent request for information data calls. It is hoped that this paper will help researchers in the SMASIS community understand the needs associated with US naval corrosion.
Comment on “Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa”
Authors: Van Tuyl Rory , Pereltsvaig Asya
Published: February 2012

Atkinson (Reports, 15 April 2011, p. 346) concluded that language originated in western Africa and that, due to a serial founder effect, languages repeatedly lost phonemes the farther they moved from the African point of origin. Independent examination of the published data tends to refute both these claims.
Visualizing Long-Term Memory Formation in Two Neurons of the
Drosophila
Brain
Authors: Chen Chun-Chao , Wu Jie-Kai , Lin Hsuan-Wen , Pai Tsung-Pin , Fu Tsai-Feng , Wu Chia-Lin , Tully Tim , Chiang Ann-Shyn
Published: February 2012

Challenging the Mushroom Bodies

Early memory is labile and is gradually consolidated over time into long-lasting, stable memory. In several species, including mammals, memory consolidation depends on protein synthesis. In
Drosophila
, long-term memory is produced by spaced repetitive training, which induces cyclic adenosine monophosphate (cAMP)–response element–binding protein (CREB)–dependent gene transcription and de novo protein synthesis. Using a large number of genetic tools,

Chen
et al.

(p.
678
; see the Perspective by

Dubnau

) localized this CREB-dependent induction of de novo protein synthesis to two dorsal-anterior-lateral neurons in the adult brain. Importantly, protein synthesis was not required within the mushroom bodies, which are usually considered to be the site of associative learning and memory in insects.
Critical Truths About Power Laws
Authors: Stumpf Michael P. H. , Porter Mason A.
Published: February 2012

Most reported power laws lack statistical support and mechanistic backing.
Ode to the Mushroom Bodies
Authors: Dubnau Josh
Published: February 2012

Neurons that stabilize memory storage are located outside of a region in the insect brain long thought to handle this task.
The Visionary
Authors: Kaiser Jocelyn
Published: February 2012

Seeking to spur drug development, Stephen Friend has launched a daring series of initiatives to make biomedical research more open and effective.
Fasting Cycles Retard Growth of Tumors and Sensitize a Range of Cancer Cell Types to Chemotherapy
Authors: Lee Changhan , Raffaghello Lizzia , Brandhorst Sebastian , Safdie Fernando M. , Bianchi Giovanna , Martin-Montalvo Alejandro , Pistoia Vito , Wei Min , Hwang Saewon , Merlino Annalisa , Emionite Laura , de Cabo Rafael , Longo Valter D.
Published: February 2012

Short-term starvation increases the effectiveness of chemotherapy against a wide range of tumor cell types.
Xenoepitope Substitution Avoids Deceptive Imprinting and Broadens the Immune Response to Foot-and-Mouth Disease Virus
Authors: Szczepanek Steven M. , Barrette Roger W. , Rood Debra , Alejo Diana , Silbart Lawrence K.
Published: February 2012

Many RNA viruses encode error-prone polymerases which introduce mutations into B and T cell epitopes, providing a mechanism for immunological escape. When regions of hypervariability are found within immunodominant epitopes with no known function, they are referred to as “decoy epitopes,” which often deceptively imprint the host's immune response. In this work, a decoy epitope was identified in the foot-and-mouth disease virus (FMDV) serotype O VP1 G-H loop after multiple sequence alignment of 118 isolates. A series of chimeric cyclic peptides resembling the type O G-H loop were prepared, each bearing a defined “B cell xenoepitope” from another virus in place of the native decoy epitope. These sequences were derived from porcine respiratory and reproductive syndrome virus (PRRSV), from HIV, or from a presumptively tolerogenic sequence from murine albumin and were subsequently used as immunogens in BALB/c mice. Cross-reactive antibody responses against all peptides were compared to a wild-type peptide and ovalbumin (OVA). A broadened antibody response was generated in animals inoculated with the PRRSV chimeric peptide, in which virus binding of serum antibodies was also observed. A B cell epitope mapping experiment did not reveal recognition of any contiguous linear epitopes, raising the possibility that the refocused response was directed to a conformational epitope. Taken together, these results indicate that xenoepitope substitution is a novel method for immune refocusing against decoy epitopes of RNA viruses such as FMDV as part of the rational design of next-generation vaccines.
Analysis of Multiple Leptospira interrogans Serovar Canicola Vaccine Proteomes and Identification of LipL32 as a Biomarker for Potency
Authors: Humphryes P. C. , Weeks M. E. , Gielbert A. , Thomson G. , Coldham N. G.
Published: February 2012

The current batch potency test forLeptospira interrogansserovar Canicola vaccines requires the use of a large number of hamsters and has severe effects (i.e., hepatic and renal failure resulting in death); while this vaccine is effective, a safer, cheaper, more ethical replacement is desired. The aim of this study was to analyze vaccine proteomes and identify target molecules common to allL. interrogansserovar Canicola vaccines which could be used to design anin vitropotency test. Initial analysis ofL. interrogansserovar Canicola vaccines (A to E) from different manufacturers, using theLimulusamebocyte lysate assay and silver-stained sodium dodecyl sulfate polyacrylamide gels, indicated that lipopolysaccharide was not present in all vaccines, preventing it from being a suitable target molecule. The protein contents of vaccines A to E were therefore determined by two-dimensional liquid chromatography mass spectrometry ([2D-LC/MS] 221 ± 31, 9 ± 8, 34 ± 4, 21 ± 5, and 34 ± 17 proteins [mean ± 1 standard deviation] found, respectively). The outer membrane protein LipL32 was established to be common to all and to be present at a significantly higher (P≤ 0.05) relative spectral abundance in a batch of vaccine which passed thein vivopotency test than in one which had failed. Further analysis using multiple reaction monitoring revealed that the concentration of the N terminus of LipL32 was significantly lower (P≤ 0.01) in failed batches (n= 2) of vaccine than in passed batches (n= 2); the concentration of the C terminus between the two batches was approximately the same. Anin vitro Leptospiravaccine potency test, based on N-terminal amino acid quantification of LipL32, was subsequently developed.
Purpureocillium lilacinum as a Cause of Cavitary Pulmonary Disease: a New Clinical Presentation and Observations on Atypical Morphologic Characteristics of the Isolate
Authors: Khan Ziauddin , Ahmad Suhail , Al-Ghimlas Fahad , Al-Mutairi Sana , Joseph Leena , Chandy Rachel , Sutton Deanna A. , Guarro Josep
Published: February 2012

The first case of cavitary pulmonary disease caused by
Purpureocillium lilacinum
is described. The isolate showed atypical microscopic characteristics similar to
Acremonium
and
Fusarium
spp., which necessitated molecular identification by sequencing of multiple conserved loci. The patient responded to voriconazole, reinforcing its therapeutic efficacy for
P. lilacinum
infections.
Production and Evaluation of Antibodies and Phage Display-Derived Peptide Ligands for Immunomagnetic Separation of Mycobacterium bovis
Authors: Stewart Linda D. , McNair James , McCallan Lyanne , Thompson Suzan , Kulakov Leonid A. , Grant Irene R.
Published: February 2012

This study describes the development and optimization of an immunomagnetic separation (IMS) method to isolate
Mycobacterium bovis
cells from lymph node tissues. Gamma-irradiated whole
M. bovis
AF2122/97 cells and ethanol-extracted surface antigens of such cells were used to produce
M. bovis
-specific polyclonal and monoclonal antibodies in rabbits and mice. They were also used to generate
M. bovis
-specific peptide ligands by phage display biopanning. The various antibodies and peptide ligands obtained were used to coat MyOne tosyl-activated Dynabeads (Life Technologies), singly or in combination, and evaluated for IMS. Initially,
M. bovis
capture from Middlebrook 7H9 broth suspensions (concentration range, 10 to 10
5
CFU/ml) was evaluated by IMS combined with an
M. bovis
-specific touchdown PCR. IMS-PCR results and, subsequently, IMS-culture results indicated that the beads with greatest immunocapture capability for
M. bovis
in broth were those coated simultaneously with a monoclonal antibody and a biotinylated 12-mer peptide. These dually coated beads exhibited minimal capture (mean of 0.36% recovery) of 12 other
Mycobacterium
spp. occasionally encountered in veterinary tuberculosis (TB) diagnostic laboratories. When the optimized IMS method was applied to various
M. bovis-
spiked lymph node matrices, it demonstrated excellent detection sensitivities (50% limits of detection of 3.16 and 57.7 CFU/ml of lymph node tissue homogenate for IMS-PCR and IMS-culture, respectively). The optimized IMS method therefore has the potential to improve isolation of
M. bovis
from lymph nodes and hence the diagnosis of bovine tuberculosis.
Comparison of the Microflex LT and Vitek MS Systems for Routine Identification of Bacteria by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry
Authors: Martiny Delphine , Busson Laurent , Wybo Ingrid , El Haj Rachid Ait , Dediste Anne , Vandenberg Olivier
Published: February 2012

This study compared the performance of three matrix-assisted laser desorption ionization–time of flight mass spectrometry systems: Microflex LT (Bruker Daltonics, Bremen, Germany), Vitek MS RUO (Axima Assurance-Saramis database; bioMérieux, Marcy l'Etoile, France), and Vitek MS IVD (bioMérieux). A total of 1,129 isolates, including 1,003 routine isolates, 73 anaerobes, and 53 bacterial enteropathogens, were tested on the Microflex LT and Axima Assurance devices. The spectra were analyzed using three databases: Biotyper (Bruker Daltonics), Saramis, and Vitek MS (bioMérieux). Among the routine isolates requiring identification to the species level (
n
= 986), 92.7% and 93.2% were correctly identified by the Biotyper and Vitek MS databases, respectively. The Vitek MS database is more specific for the identification of
Streptococcus viridans
. For the anaerobes, the Biotyper database often identified
Fusobacterium
isolates to only the genus level, which is of low clinical significance, whereas 20% of the
Bacteroides
species were not identified or were misidentified by the Vitek MS database. For the enteropathogens, the poor discrimination between
Escherichia coli
and
Shigella
explains the high proportion of unidentified organisms. In contrast to the Biotyper database, the Vitek MS database properly discriminated all of the
Salmonella entrica
serovar Typhi isolates (
n
= 5). The performance of the Saramis database was globally poorer. In conclusion, for routine procedures, the Microflex LT and Vitek-MS systems are equally good choices in terms of analytical efficiency. Other factors, including price, work flow, and lab activity, will affect the choice of a system.
Development of Mitochondrial Loop-Mediated Isothermal Amplification for Detection of the Small Liver Fluke Opisthorchis viverrini (Opisthorchiidae; Trematoda; Platyhelminthes)
Authors: Le Thanh Hoa , Nguyen Nga Thi Bich , Truong Nam Hai , De Nguyen Van
Published: February 2012

Mitochondrial DNA sequences offer major advantages over the more usual nuclear targets for loop-mediated isothermal amplification approaches (mito-LAMP) because multiple copies occur in every cell. Four LAMP primers [F3, FIP(F1c+F2), BIP(B1c+B2), and B3] were designed based on the mitochondrial
nad1
sequence of
Opisthorchis viverrini
and used for a highly specific assay (mito-OvLAMP) to distinguish DNA of
O. viverrini
from that of another opisthorchiid (
Clonorchis sinensis
) and other trematodes (
Haplorchis pumilio
,
Haplorchis taichui
,
Fasciola hepatica
, and
Fasciola gigantica
). Conventional PCR was applied using F3/B3 primer pairs to verify the specificity of the primers for
O. viverrini
DNA templates. All LAMP-positive samples could be detected with the naked eye in sunlight, by gel electrophoresis (stained with ethidium bromide), and by addition of SYBR green I to the product in sunlight or under UV light. Only DNA from
O. viverrini
yielded amplification products by LAMP (and by PCR verification), and the LAMP limit of detection was as little as 100 fg (10
−4
ng DNA), indicating that this assay is 10 to 100 times more sensitive than PCR. Field testing was done using representative egg and metacercarial samples collected from localities where the fluke is endemic. With the advantages of simplicity, rapidity, sensitivity, and cost effectiveness, mito-OvLAMP is a good tool for molecular detection and epidemiology studies in regions or countries where
O. viverrini
is endemic, which can lead to more effective control of opisthorchiasis and trematodiasis.
Contribution of Amoebic Coculture to Recovery of Legionella Isolates from Respiratory Samples: Prospective Analysis over a Period of 32 Months
Authors: Descours G. , Suet A. , Ginevra C. , Campese C. , Slimani S. , Ader F. , Che D. , Lina G. , Jarraud S.
Published: February 2012

We evaluated the contribution of amoebic coculture to the recovery of
Legionella
spp. from 379 respiratory samples. The sensitivity of axenic culture was 42.1%. The combination of axenic culture with amoebic coculture increased the
Legionella
isolation rate to 47.1%. Amoebic coculture was particularly efficient in isolating
Legionella
spp. from respiratory samples contaminated with oropharyngeal flora.
Discovery of Potential Diagnostic and Vaccine Antigens in Herpes Simplex Virus 1 and 2 by Proteome-Wide Antibody Profiling
Authors: Kalantari-Dehaghi Mina , Chun Sookhee , Chentoufi Aziz Alami , Pablo Jozelyn , Liang Li , Dasgupta Gargi , Molina Douglas M. , Jasinskas Algis , Nakajima-Sasaki Rie , Felgner Jiin , Hermanson Gary , BenMohamed Lbachir , Felgner Philip L. , Davies D. Huw
Published: February 2012

Routine serodiagnosis of herpes simplex virus (HSV) infections is currently performed using recombinant glycoprotein G (gG) antigens from herpes simplex virus 1 (HSV-1) and HSV-2. This is a single-antigen test and has only one diagnostic application. Relatively little is known about HSV antigenicity at the proteome-wide level, and the full potential of mining the antibody repertoire to identify antigens with other useful diagnostic properties and candidate vaccine antigens is yet to be realized. To this end we produced HSV-1 and -2 proteome microarrays inEscherichia coliand probed them against a panel of sera from patients serotyped using commercial gG-1 and gG-2 (gGs for HSV-1 and -2, respectively) enzyme-linked immunosorbent assays. We identified many reactive antigens in both HSV-1 and -2, some of which were type specific (i.e., recognized by HSV-1- or HSV-2-positive donors only) and others of which were nonspecific or cross-reactive (i.e., recognized by both HSV-1- and HSV-2-positive donors). Both membrane and nonmembrane virion proteins were antigenic, although type-specific antigens were enriched for membrane proteins, despite being expressed inE. coli.
Tiled Microarray Identification of Novel Viral Transcript Structures and Distinct Transcriptional Profiles during Two Modes of Productive Murine Gammaherpesvirus 68 Infection
Authors: Cheng Benson Yee Hin , Zhi Jizu , Santana Alexis , Khan Sohail , Salinas Eduardo , Forrest J. Craig , Zheng Yueting , Jaggi Shirin , Leatherwood Janet , Krug Laurie T.
Published: February 2012

We applied a custom tiled microarray to examine murine gammaherpesvirus 68 (MHV68) polyadenylated transcript expression in a time course of
de novo
infection of fibroblast cells and following phorbol ester-mediated reactivation from a latently infected B cell line. During
de novo
infection, all open reading frames (ORFs) were transcribed and clustered into four major temporal groups that were overlapping yet distinct from clusters based on the phorbol ester-stimulated B cell reactivation time course. High-density transcript analysis at 2-h intervals during
de novo
infection mapped gene boundaries with a 20-nucleotide resolution, including a previously undefined ORF73 transcript and the MHV68 ORF63 homolog of Kaposi's sarcoma-associated herpesvirus vNLRP1. ORF6 transcript initiation was mapped by tiled array and confirmed by 5′ rapid amplification of cDNA ends. The ∼1.3-kb region upstream of ORF6 was responsive to lytic infection and MHV68 RTA, identifying a novel RTA-responsive promoter. Transcription in intergenic regions consistent with the previously defined expressed genomic regions was detected during both types of productive infection. We conclude that the MHV68 transcriptome is dynamic and distinct during
de novo
fibroblast infection and upon phorbol ester-stimulated B cell reactivation, highlighting the need to evaluate further transcript structure and the context-dependent molecular events that govern viral gene expression during chronic infection.
The Majority of Freshly Sorted Simian Immunodeficiency Virus (SIV)-Specific CD8+T Cells Cannot Suppress Viral Replication in SIV-Infected Macrophages
Authors: Vojnov Lara , Martins Mauricio A. , Bean Alexander T. , Veloso de Santana Marlon G. , Sacha Jonah B. , Wilson Nancy A. , Bonaldo Myrna C. , Galler Ricardo , Stevenson Mario , Watkins David I.
Published: February 2012

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) primarily infect activated CD4+T cells but can infect macrophages. Surprisingly,ex vivotetramer-sorted SIV-specific CD8+T cells that eliminated and suppressed viral replication in SIV-infected CD4+T cells failed to do so in SIV-infected macrophages. It is possible, therefore, that while AIDS virus-infected macrophages constitute only a small percentage of all virus-infected cells, they may be relatively resistant to CD8+T cell-mediated lysis and continue to produce virus over long periods of time.
Discovery of Retroviral Homologs in Bats: Implications for the Origin of Mammalian Gammaretroviruses
Authors: Cui Jie , Tachedjian Mary , Wang Lina , Tachedjian Gilda , Wang Lin-Fa , Zhang Shuyi
Published: February 2012

Gammaretroviruses infect a wide range of vertebrate species where they are associated with leukemias, neurological diseases and immunodeficiencies. However, the origin of these infectious agents is unknown. Through a phylogenetic analysis of viral gene sequences, we show that bats harbor an especially diverse set of gammaretroviruses. In particular, phylogenetic analysis places
Rhinolophus ferrumequinum
retrovirus (RfRV), a new gammaretrovirus identified by
de novo
analysis of the
Rhinolophus ferrumequinum
transcriptome, and six other gammaretroviruses from different bat species, as basal to other mammalian gammaretroviruses. An analysis of the similarity in the phylogenetic history between the gammaretroviruses and their bat hosts provided evidence for both host-virus codivergence and cross-species transmission. Taken together, these data provide new insights into the origin of the mammalian gammaretroviruses.