bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Response of Soap and Synthetic Base Greases
Authors: Bogie K. D.
Published: September 2011

The majority of non-Newtonian materials exhibit an out-of-phase stress-strain relationship (i.e., evidenced by the fundamental and associated harmonics) over a wide range of frequencies. This nonlinear response of the material when subjected to a periodic disturbance of amplitude γ, say, may be due in part to viscoelasticity, thixotropy, or a combination of the two. Other factors such as particle size and concentration can also contribute to this effect. Apparatus has been developed which enables harmonic analysis to be carried out with comparative ease in the low to mid-frequency range; the nonlinear response of a material offers no experimental problems. The experimental work reported here on a soap and synthetic base grease confirms the views that: Greases are nonlinear viscoelastic in response over the whole range of strain amplitude, frequencies, and temperatures investigated. Particle size and concentration are observed to influence the flow stability of each grease. At small strain amplitudes the synthetic base grease is mainly elastic in response, but the stress moves out-of-phase with strain as the strain amplitude is increased. The behavior of the stress fundamental component suggests yielding of the structure. The harmonic content appears to be more sensitive to changes in strain amplitude and temperature than the fundamentals. The method of reduced variable has been applied to the fundamental and associated harmonics with reasonable success, supporting the implications of this method that increasing the temperature is equivalent to decreasing the frequency. An approximate method of correlating dynamic and steady shearing motion results in terms of the function α (phase shift in dynamic response) is outlined, the resulting correlation being difficult to apply mainly because of the mathematical shortcomings.
Externally Pressurized Bearings—II: Vibration Attenuators
Authors: Wilcock D. F. , BeVier W. E
Published: September 2011

Rolling element bearings are vibration generators, and in addition are stiff, so that they transmit rotor generated noise as well to the machine frame and casing. Self-acting (hydrodynamic) bearings are also very rigid, so that they are excellent transmitters of rotor generated vibration, e.g., front gear teeth, turbine blading, or magnetic hysteresis. A typical rotor weighing 1000 lb may be supported on bearings having a stiffness of 3 × 106 lb/in., and hence will be a good vibration transmitter up to a frequency of 172 cps. Hydrostatic bearings afford an opportunity to control the bearing frequency response so that attenuation of middle and high frequencies can be secured. Analysis of the hydrostatic bearing as a closed-loop servomechanism reveals methods of designing them for attenuation without serious consequences in other performance factors. They may be used as the primary bearing, or as separate isolator bearings in conjunction with rolling element or self-acting bearings. Some examples of possible applications are discussed.
An Investigation of Permanent Deformation (Brinelling) of Ball and Roller Specimens
Authors: Williams F. J. , Schwartz K. P.
Published: September 2011

The conventional method of calculating static load allowables for rolling element bearings is based on a brinell which will not affect the rotational fatigue life of the bearing. For an oscillating bearing requiring only limited cycle life, this is a very conservative approach. Increased allowables are possible where static allowables are based on 2/3 of the fracture capacity of the bearing, provided performance of the bearing is not adversely affected by these loads. Results of tests performed on one in. dia balls and 3/8 in. dia rollers are reported. Fracture capacities were determined and permanent deformation as a function of load is listed for the five material combinations tested. Permanent deformation variation at temperatures to 1500 F is discussed. The effect of lubricants and the significance of brinell indentations on rolling friction and on endurance life is reported. Static allowables based on maximum Hertz stress values are listed for each material combination from data obtained. These allowables are much higher than those presently used. Maximum Hertz stress static allowables to 1,000,000 psi can be considered with high strength steel for both ball and roller specimens. Tests on six and one half in. dia ball and roller bearings confirmed that the bearings could withstand very high static loads and still operate at high dynamic loads for the number of cycles required in wing pivots and other similar applications.
Review of Gas-Bearing Gyro Development in the United Kingdom
Authors: Patterson A. G.
Published: September 2011

This paper describes development and progress in the application of aerodynamic gas bearings to gyro-spin axes in the United Kingdom since early 1959, when work in this field was begun by the British Navy Department. Since that time, about a dozen organizations have become engaged in or are closely associated with such work. Most applications hitherto have been government-sponsored, and are concerned with marine, air, or space navigation or stabilization, but work, for the commercial market, particularly to meet needs in the aviation industry, is being vigorously carried out. The organizations involved in or associated with gas-bearing gyro work and their specific interests are summarized in Tables 1 and 2 covering naval, aviation, space, and commercial interests, respectively. Further details are given in the text in some of the cases where more advanced R&D or production stages have been reached. The greater complexity and the more exacting requirements of gyros of higher precision, such as are needed for marine inertial navigation, have made necessary the evolution not only of higher accuracy machining and metrology, achieved with cooperation from British Industry, but also of new techniques for dynamic measurements. Some of the highlights of associated technologies are summarized but fuller information is given in the references. In addition, unforeseen starting problems have triggered off programs of work on specialized aspects of cleaning and boundary lubrication which, although hitherto incomplete, are yielding promising results. Inertial navigation, weapon and general stabilization gyros for the Navy Department are now in full industrial production. Other classes in the U.K. have reached advanced stages of R&D and continuing expansion on work in both marine and air classes of gas-bearing gyros is expected. Closer association within the field of general gas-bearing technology both within the United Kingdom and abroad is being actively sought, particularly by government and university orgnizations in the expectation that long-term mutual benefits will follow.
The Effect of Viscous and Pressure Gradient Torques on a Free-Rotor Gyroscope
Authors: Zedekar S. L.
Published: September 2011

The equations are derived for the torques on a spherical rotor. Using suitable transformation matrices, these error torques are related to the bearing compliances and the so-called g2 coefficients. The method of determining these coefficients is indicated, using the experimental technique of tumble testing the gyroscope.
A Numerical Solution for the Design of Externally Pressurized Porous Gas Bearings: Thrust Bearings
Authors: Gargiulo E. P. , Gilmour P. W.
Published: September 2011

A numerical solution for the flow in a porous bearing is presented which includes provision for compressibility of the lubricant and anisotropic permeability of the porous media. Typical design curves for the bearing load and flow are included with experimental verification.
Material Considerations for High Temperature Tilting Pad Gas Bearings
Authors: Murray S. F. , Peterson M. B.
Published: September 2011

This paper is concerned with the sliding contact problems encountered in tilting pad gas bearings operating at temperatures up to 1400 deg F. Both the pivots and the bearing surfaces are considered. Short time experimental evaluations of pivot damage are summarized. The results of start-stop and high-speed rub tests on a single tilting pad hydrodynamic bearing are also described. Based on the results obtained to date, damage-resistant coatings are available for use on the bearing surfaces at high temperature. There are also suitable pivot materials, but the pivot must be properly designed to minimize slip in the contact area.
An Investigation of Methods to Improve the Wear Resistance of Gas-Bearing Ceramic Materials
Authors: Rowe H. H.
Published: September 2011

Ceramic materials, or more particularly aluminum oxides, have found application as a practical gas-bearing material because of the dimensional stability, low coefficient of friction, high hardness, and ability to attain good surface finish that these materials possess. This paper reports on an investigation of a number of methods designed to improve the resistance of aluminum oxide to damage from sliding contact, and hence improve the start-stop life characteristics of gas-bearing assemblies. These methods include heat-treatment, neutron irradiation treatment, gold plating, and coating of alumina surfaces by means of a chemical vapor deposition technique, in order to increase the wear resistance of the material. A brief mention is also made of the effect of machining techniques as they relate to the finish, and hence to the wear resistance, of gas-bearing parts.
The Effect of Ausforming on the Rolling Contact Fatigue Life of a Typical Bearing Steel
Authors: Bamberger E. N.
Published: September 2011

A development program has been conducted on M-50 to determine the improvements possible in bearing steels by the incorporation of a hot-cold working (ausforming) treatment in their processing. Primary emphasis was on the improvements possible in rolling contact fatigue. In support of this, heat-treat, corrosion, hardness, and microstructural studies have been performed. It has been shown that a certain process for working steel in the metastable austenitic condition as applied to the rolling contact fatigue life of M-50 bearing steel will substantially improve life, thereby increasing bearing reliability. The remarkable improvements in life (exceeding 800 percent) will be a significant factor in meeting the long-life-bearing requirements for advanced air-breathing propulsion systems. A metallurgical analysis has been conducted and a mechanism is proposed which is thought to be the primary factor in providing the significant improvements in rolling contact fatigue life. It is shown that these improvements in life are possible without any significant increase in hardness of the subject materials. Evidence is presented which indicates that the life improvement is primarily due to more uniform carbide dispersion, reduction of massive carbide particles, and reduction in martensite platelet size. These microstructural changes are believed to be associated with strain-induced precipitation and its interplay with strain-hardening during the deformation cycle.
Reversing Normal Strains Produced by Rolling Contact Load
Authors: Lyman J.
Published: September 2011

Attempts have been made to correlate some characteristic of the stress field produced by rolling contact loads with the location of the origin of the rolling contact fatigue failure process. Analysis of the stress field of a cylinder and torus under contact load reveals the existence of a reversing normal strain in certain directions at points in the material. Research work indicates this condition to be a requirement for large plastic deformations in high cycle fatigue. Similarities of conditions for fatigue in reversed bending, torsional yield processes, and reversed cyclic deformation in torsion suggest the significance of the reversing normal strain in rolling contact stress fields.
Friction-Induced Vibration
Authors: Brockley C. A. , Cameron R. , Potter A. F.
Published: September 2011

Friction-induced vibration has been studied in a system consisting of an elastically suspended, damped slider which is loaded against a surface moving at a constant velocity. Exact analysis reveals a critical velocity which limits the incidence of vibration. The critical velocity depends on damping, load, stiffness, and friction characteristics which vary with time and velocity. Approximations in the theory yield an amplitude-velocity equation and another critical velocity relationship. Reasonable agreement is found to exist between the exact and approximate theories for critical velocity. Experimental results for several systems illustrate amplitude-velocity relationships and the existence of critical velocities. The correlation between the experimental results and the approximate theory indicates that the analytical method could be used to predict the vibration behavior of actual systems.
Behavior of a Pivoted-Pad Thrust Bearing During Start-Up
Authors: Gustafson R. E.
Published: September 2011

Starting tests were made on a pivoted-pad thrust bearing of 23-in. major diameter, subjected to a loading of 723 psi for various periods of time prior to start. Records of oil-film thicknesses and pressures, and of torque and individual thrust-pad loadings, showed details of the action of the bearing during torque buildup, at breakaway, and during acceleration. It was found that breakaway torques were lower than expected and were not influenced by the period of static loading prior to starting so long as the period exceeded 1 hr. The adverse effects of interruptions of the surface of the thrust-collar facing plates were shown.
Thermal Distortion of Spiral-Grooved Gas-Lubricated Thrust Bearing Due to Self-Heating
Authors: Pan C. H. T. , Sternlicht B.
Published: September 2011

The effects of thermal distortion due to viscous heating in the fluid film on the performance of a spiral-grooved, gas-lubricated thrust bearing are analyzed. A numerical example shows that considerable loss of load capacity is possible for bearings made of common structural materials. A simple criterion has been developed to check the importance of this type of thermal distortion.
A General Solution of Reynolds’ Equation for a Full Finite Journal Bearing
Authors: Donaldson R. R.
Published: September 2011

Reynolds’ equation for a full finite journal bearing lubricated by an incompressible fluid is solved by separation of variables to yield a general series solution. A resulting Hill equation is solved by Fourier series methods, and accurate eigenvalues and eigenvectors are calculated with a digital computer. The finite Sommerfeld problem is solved as an example, and precise values for the bearing load capacity are presented. Comparisons are made with the methods and numerical results of other authors.
Spherical Squeeze-Film Hybrid Bearing With Small Steady-State Radial Displacement
Authors: Chiang T. , Malanoski S. B. , Pan C. H. T.
Published: September 2011

Spherical squeeze-film hybrid bearings were analyzed theoretically. Based on an asymptotic approximation for large squeeze number, the solution of the Reynolds’ equation applicable to the system under investigation was obtained. Perturbation method has been used; the results are valid for small radial displacement only. It has no limitation, however, in the values of compressibility number, axial displacement ratio, and excursion ratio. Numerical calculations have been programmed on the GE205 computer. Axial load capacity, axial stiffness, and radial and tangential stiffnesses were obtained.
Analysis and Design of Spiral-Groove Bearings
Authors: Muijderman E. A.
Published: September 2011

The paper starts with a brief description of the history of the spiral-groove bearing. All previous authors based their considerations on a recurrent pattern of parallel straight grooves, for which Whipple gave an approximate solution which has served as the basis for practically all further theoretical work. The agreement between the theory based on this model and the real spiral-groove bearing is rather poor. In the present paper, the author describes how he found a method of calculation which applies directly to a real spiral-groove bearing with logarithmic spirals, working with an incompressible medium. This theory also takes the end effects into account. Following on this, dimensionless graphs and tables are given for the most commonly occurring types of spiral-groove bearings in such a form that they can be used directly for design purposes.
The MHD Hydrostatic Thrust Bearing—Theory and Experiments
Authors: Krieger R. J. , Day H. J. , Hughes W. F.
Published: September 2011

An analytical and experimental investigation is made of magnetohydrodynamic lubrication flow between parallel stationary disks in an axial magnetic field. The effect of the fluid inertia is analyzed by a single iteration of the appropriate differential equations. For a given pressure, the approximate solution indicates that the inertia forces increase the load capacity and flow rate. Experimental flow rates are obtained by varying the Hartmann number with a constant head and by varying the head with a constant Hartmann number. Good agreement is found between the theory and experimental results until the transition to turbulent flow occurs. The effect of the magnetic field on this transition is evident from the data.
On the Possibilities of Magnetogasodynamic Lubrication
Authors: Constantinescu V. N.
Published: September 2011

The problem of gas film lubrication is considered, by assuming the existence of an electrical conductibility for the gas and that the motion is subjected to the influence of external electromagnetic fields. The MGD-lubrication equations are written under a general form. Several external electromagnetic conditions are considered, divided in two classes: (a) transversal magnetic field, and (b) tangential magnetic field combined with transversal electrical field. For each case the pressure differential equation is deduced and the possibilities of obtaining approximate solutions are briefly discussed, as well as the existence of some limiting solutions. Finally, the possibilities of improving the operation of both self-acting and externally pressurized gas bearings are pointed out.
Magnetohydrodynamic Effects in Composite Bearings
Authors: Prakash J.
Published: September 2011

A theoretical analysis is made of a composite slider bearing using an electrically conducting lubricant such as a liquid metal in the presence of a magnetic field applied perpendicular to the bearing surfaces. Two solutions are presented for large and small values of Hartmann number. It is found that for large Hartmann number significant increase in load capacity can be obtained even under open circuit condition. Short circuit condition results in zero load capacity, under the approximation considered. At small Hartmann number only a slight increase occurs under open circuit condition and external power must be supplied to get a significant increase. It is seen that a magnetohydrodynamic composite bearing does not always give an increase in load capacity as compared to an equivalent inclined slider bearing, as is the case with classical composite bearing. There is a critical Hartmann number depending on the parameters of the problem, above which MHD effects reduce the load capacity as compared to the case of an equivalent inclined slider bearing. It is also observed that the frictional drag on the bearing can be made zero by supplying electrical energy through the electrodes to the fluid.
Parallel Surface Squeeze Films: The Effect of the Variation of Viscosity With Temperature and Pressure
Authors: Gould P.
Published: September 2011

A study is presented of high-pressure squeeze films between flat disks which approach each other at a constant velocity. The dependence of the viscosity of the oil on the fluid temperature and pressure is included in the momentum and energy equations. A single dimensionless parameter which involves only fluid properties determines whether the load capacity will be greater or less than that predicted by an isoviscous analysis. Excellent agreement is found between the results of a numerical analysis and the results of experiments in which mineral oil is confined between steel boundaries.
The Effect of Elastic Distortions on Journal Bearing Performance
Authors: O’Donoghue J. , Brighton D. K. , Hooke C. J. K.
Published: September 2011

This paper presents a solution to the problem of hydrodynamic lubrication of journal bearings taking into account the elastic distortions of the shaft and the bearing. The exact solution for determining the elastic deformation for a given pressure distribution around a bearing is given, together with the reiterative procedure adopted to find the pressure distribution which satisfies both the hydrodynamic and elastic requirements of the system. Results are given which have been derived for a material with a Poisson’s ratio of 0.28, but other values such as 0.33 do not incur substantial errors. The results can be applied to a wide range of operating conditions using the nondimensional group of terms suggested in the paper. The bearing is assumed to be infinite in length, and infinite in thickness. The latter assumption is shown to be valid for a particular case where the outside diameter of the bearing shell is 3.5 times the shaft diameter. A further assumption in the calculation is a condition of constant viscosity of the lubricant existing around the bearing.
On the Field of Temperatures in Lubricating Films
Authors: Tipei N. , Nica Al.
Published: September 2011

The temperature distribution in the lubricating film of journal bearings for the three-dimensional case is obtained by using the results already known regarding the pressure distribution in the film and by integrating the energy equation. Relations for the divergent and convergent zones of the bearing are established by taking into account the viscosity and the side leakage; the distribution of the temperature along the bearing width is also considered. Comparisons between the theoretical values and experimental measurements are also performed, resulting in good agreement.
On the Analytical and Experimental Investigation of a Hydrostatic, Axisymmetric Compliant-Surface Thrust Bearing
Authors: Castelli V. , Rightmire G. K. , Fuller D. D.
Published: September 2011

The paper presents experimental and theoretical data on the axisymmetric hydrostatic thrust bearing with one bonded compliant surface. The theoretical results are exact and are based on linear elasticity theory. The effects of compliance on the behavior of the thrust bearing are discussed and illustrated.
Cylindrical IEC Fusion Neutron Source for Broad Area NAA
Authors: Miley George H. , Momota Hiromu , Leon Hugo , Ulmen Ben , Amadio Guilherme , Khan Atanu , Chen George , Matisiak William , Azeem Ali , Keutelian Paul
Published: September 2011

The development of a unique long cylindrical neutron source for broad area neutron activation analysis (NAA) is presented. This source uses inertial electrostatic confinement (IEC) to produce 2.54 MeV D-D or 14.1 MeV D-T fusion neutrons. The IEC offers a variety of applications ranging from security inspection stations to driven-subcritical research assemblies. This IEC design uses a biased grid to initial in a unique “star” mode plasma discharge creating beam-background gas (target) fusion reactions. They routinely produce ∼108 2.54 MeV D-D neutrons/s at steady state. Pulsed operation has achieved upto 109n/s. (∼1011n/s if a deuterium mixture is used). Indeed, a version of the IEC has been commercially produced as a portable neutron source for industrial NAA applications. While that IEC source used spherical geometry, the present work uses a cylindrical version which provides a unique long “linelike” neutron source for use in the present broad area NAA system.
Thermo-Mechanical Response of Thru-Silicon Vias Under Local Thermal Transients Using Experimentally Validated Finite Element Models
Authors: Wakil Jamil A. , Dehaven Patrick W. , Klymko Nancy R. , Chen Shaochen
Published: September 2011

Significant research has focused on the reliability of through-silicon-vias (TSVs) under conventional uniform thermal loading conditions such as accelerated thermal cycling (0–100 °C) or deep thermal cycling (−40–125 °C). This study analyzes the thermomechanical behavior of TSVs in 3D packages undergoing rapid local temperature fluctuations, as would be experienced in actual operation. A global/local finite element model is used to analyze the TSV behavior at various distances from the thermal fluctuation site. Transient thermal measurements, warpage and in-plane deformation measurements, as well as micro-Raman spectroscopy measurements are used to validate the model. The results reveal that the short term local temperature transients have minimal impact on the TSV stress state regardless of TSV location, implying that global package- induced stresses dominate.
Prediction of Electromigration Failure of Solder Joints and Its Sensitivity Analysis
Authors: Liang Lihua , Zhang Yuanxiang , Liu Yong
Published: September 2011

Electromigration (EM) in solder joints under high current density has become a critical reliability issue for the future high density microelectronic packaging. This paper presents atomic density redistribution algorithm for predicting electromigration induced void nucleation and growth in solder joints of Chip Scale Package (CSP) structure. The driving force for electromigration induced failure considered here includes the electron wind force, stress gradients, temperature gradients, as well as the atomic density gradient, which were neglected in many of the existing studies on electromigration. The simulation results for void generation and time to failure (TTF) are discussed and correlated with the previous test results. EM sensitivity analysis is also performed to investigate the effect of EM parameters and mechanical properties of material on electromigration failure. The simulation results indicated that the atomic density on the activation energy is quite sensitive, and the mechanical material parameters have no impact on EM sensitivity of normalized atomic density.
Cracking of the Intermetallic Compound Layer in Solder Joints Under Drop Impact Loading
Authors: An Tong , Qin Fei
Published: September 2011

The significant difference between failure modes of lead-containing and lead-free solder joints under drop impact loading remains to be not well understood. In this paper, we propose a feasible finite element approach to model the cracking behavior of solder joints under drop impact loading. In the approach, the intermetallic compound layer/solder bulk interface is modeled by the cohesive zone model, and the crack driving force in the intermetallic compound layer is evaluated by computing the energy release rate. The numerical simulation of a board level package under drop impact loading shows that, for the lead-containing Sn37Pb solder joint, the damage in the vicinity of the intermetallic compound layer initiates earlier and is much greater than that in the lead-free Sn3.5Ag solder joint. This damage relieves the stress in the intermetallic compound layer and reduces the crack driving force in it and consequently alleviates the risk of the intermetallic compound layer fracturing.
Releasable infrared metamaterials
Authors: D’Archangel J. A. , Boreman G. D. , Shelton D.J. , Sinclair M. B. , Brener I.
Published: September 2011

Infrared metamaterial arrays containing Au elements immersed in a medium of benzocyclobutene (BCB) were fabricated and selectively etched to produce small square flakes with edge dimensions of approximately 20 μm. Two unit-cell designs were fabricated successfully: one employed crossed-dipole elements while the other utilized square-loop elements (the latter design was symmetric about a Cr ground plane). Infrared spectral reflectivity measurements from collected flakes were compared to infinite-surface simulations in Ansoft HFSS and spectral reflectance measurements of full array samples. Good agreement was found between modeled and experimental resonant behavior when taking into account the proportionality of flakes filling the input aperture of the measurement apparatus.
Manipulation of polycrystalline TiO2 carrier concentration via electrically active native defects
Authors: Sellers Meredith C. K. , Seebauer Edmund G.
Published: September 2011

There is good reason to believe that the properties of semiconducting metal oxides for catalytic applications can be improved when designed according to the principles of microelectronic devices. Nevertheless, defect engineering of polycrystalline TiO2 is complicated by native charged point defects and grain boundaries that alter bulk carrier concentration in a manner that depends on synthesis and post-treatment protocols. These influences are difficult to decouple with standard electrical characterization methods, which typically induce rectifying Schottky barriers to wide-bandgap semiconductors like TiO2. Here, TiO2 donor carrier concentration (Nd) is investigated as a function of film thickness and annealing time using a rigorous Schottky diode-based electrical characterization approach. Nd scales inversely with film thickness due to a reduction in the concentration of electrically active grain boundaries in the bulk. Annealing of polycrystalline TiO2 at 550 °C induces film densification that reduces the void volume surface area available for charge trapping. Strategies for defect engineering polycrystalline metal oxides must focus on tuning electrical activity of grain boundaries and intergranular voids for successful control and manipulation of Nd.
Donor Myocardial Infarction Impairs the Therapeutic Potential of Bone Marrow Cells by an Interleukin-1–Mediated Inflammatory Response
Authors: Wang Xiaoyin , Takagawa Junya , Lam Viola C. , Haddad Daniel J. , Tobler Diana L. , Mok Pamela Y. , Zhang Yan , Clifford Brian T. , Pinnamaneni Kranthi , Saini Shereen A. , Su Robert , Bartel Maya J. , Sievers Richard E. , Carbone Larry , Kogan Scott , Yeghiazarians Yerem , Hermiston Michelle L. , Springer Matthew L.
Published: September 2011

Inflammation after myocardial infarction may explain failure of bone marrow cells to improve cardiac function in infarcted recipient hearts.
What Can a UN Health Summit Do?
Authors: Nugent Rachel A. , Jamison Dean T.
Published: September 2011

A United Nations high level summit meeting on noncommunicable diseases will set priorities for addressing this major threat to the health of both developing and developed nations.
Reservoir Targeted Vaccine for Lyme Borreliosis Induces a Yearlong, Neutralizing Antibody Response to OspA in White-Footed Mice
Authors: Meirelles Richer Luciana , Aroso Miguel , Contente-Cuomo Tania , Ivanova Larisa , Gomes-Solecki Maria
Published: September 2011

Lyme disease is caused by the spirochete
Borrelia burgdorferi
. The enzootic cycle of this pathogen requires that
Ixodes
spp. acquire
B. burgdorferi
from infected wildlife reservoirs and transmit it to other uninfected wildlife. At present, there are no effective measures to control
B. burgdorferi
; there is no human vaccine available, and existing vector control measures are generally not acceptable to the public. However, if
B. burgdorferi
could be eliminated from its reservoir hosts or from the ticks that feed on them, the enzootic cycle would be broken, and the incidence of Lyme disease would decrease. We developed OspA-RTV, a reservoir targeted bait vaccine (RTV) based on the immunogenic outer surface protein A (OspA) of
B. burgdorferi
aimed at breaking the natural cycle of this spirochete. White-footed mice, the major reservoir species for this spirochete in nature developed a systemic OspA-specific IgG response as a result of ingestion of the bait formulation. This immune response protected white-footed mice against
B. burgdorferi
infection upon tick challenge and cleared
B. burgdorferi
from the tick vector. In performing extensive studies to optimize the OspA-RTV for field deployment, we determined that mice that consumed the vaccine over periods of 1 or 4 months developed a yearlong, neutralizing anti-OspA systemic IgG response. Furthermore, we defined the minimum number of OspA-RTV units needed to induce a protective immune response.
Equine Botulinum Antitoxin for the Treatment of Infant Botulism
Authors: Vanella de Cuetos Elida E. , Fernandez Rafael A. , Bianco María I. , Sartori Omar J. , Piovano María L. , Lúquez Carolina , de Jong Laura I. T.
Published: September 2011

Infant botulism is the most common form of human botulism in Argentina and the United States. BabyBIG (botulism immune globulin intravenous [human]) is the antitoxin of choice for specific treatment of infant botulism in the United States. However, its high cost limits its use in many countries. We report here the effectiveness and safety of equine botulinum antitoxin (EqBA) as an alternative treatment. We conducted an analytical, observational, retrospective, and longitudinal study on cases of infant botulism registered in Mendoza, Argentina, from 1993 to 2007. We analyzed 92 medical records of laboratory-confirmed cases and evaluated the safety and efficacy of treatment with EqBA. Forty-nine laboratory-confirmed cases of infant botulism demanding admission in intensive care units and mechanical ventilation included 31 treated with EqBA within the 5 days after the onset of signs and 18 untreated with EqBA. EqBA-treated patients had a reduction in the mean length of hospital stay of 23.9 days (P= 0.0007). For infants treated with EqBA, the intensive care unit stay was shortened by 11.2 days (P= 0.0036), mechanical ventilation was reduced by 11.1 days (P= 0.0155), and tube feeding was reduced by 24.4 days (P= 0.0001). The incidence of sepsis in EqBA-treated patients was 47.3% lower (P= 0.0017) than in the untreated ones. Neither sequelae nor adverse effects attributable to EqBA were noticed, except for one infant who developed a transient erythematous rash. These results suggest that prompt treatment of infant botulism with EqBA is safe and effective and that EqBA could be considered an alternative specific treatment for infant botulism when BabyBIG is not available.
Development and Evaluation of an Enzyme-Linked Immunosorbent Assay for Use in the Detection of Bovine Tuberculosis in Cattle
Authors: Waters W. R. , Buddle B. M. , Vordermeier H. M. , Gormley E. , Palmer M. V. , Thacker T. C. , Bannantine J. P. , Stabel J. R. , Linscott R. , Martel E. , Milian F. , Foshaug W. , Lawrence J. C.
Published: September 2011

As a consequence of continued spillover of
Mycobacterium bovis
into cattle from wildlife reservoirs and increased globalization of cattle trade with associated transmission risks, new approaches such as vaccination and novel testing algorithms are seriously being considered by regulatory agencies for the control of bovine tuberculosis. Serologic tests offer opportunities for identification of
M. bovis
-infected animals not afforded by current diagnostic techniques. The present study describes assay development and field assessment of a new commercial enzyme-linked immunosorbent assay (ELISA) that detects antibody to
M. bovis
antigens MPB83 and MPB70 in infected cattle. Pertinent findings include the following: specific antibody responses were detected at ∼90 to 100 days after experimental
M. bovis
challenge, minimal cross-reactive responses were elicited by infection/sensitization with nontuberculous
Mycobacterium
spp., and the apparent sensitivity and specificity of the ELISA with naturally infected cattle were 63% and 98%, respectively, with sensitivity improving as disease severity increased. The ELISA also detected infected animals missed by the routine tuberculin skin test, and antibody was detectable in bulk tank milk samples from
M. bovis
-infected dairy herds. A high-throughput ELISA could be adapted as a movement, border, or slaughter surveillance test, as well as a supplemental test to tuberculin skin testing.
Molecular Epidemiology of Carbapenem-Nonsusceptible Acinetobacter baumannii in the United States
Authors: Adams-Haduch Jennifer M. , Onuoha Ezenwa O. , Bogdanovich Tatiana , Tian Guo-Bao , Marschall Jonas , Urban Carl M. , Spellberg Brad J. , Rhee Diane , Halstead Diane C. , Pasculle Anthony W. , Doi Yohei
Published: September 2011

Acinetobacter baumannii
is emerging as an important nosocomial pathogen worldwide. We report molecular epidemiology of 65 carbapenem-nonsusceptible
A. baumannii
isolates identified from hospitals in New York, Pennsylvania, Florida, Missouri, Nevada, and California between 2008 and 2009. All isolates were subjected to pulsed-field gel electrophoresis (PFGE). Select isolates then underwent multilocus sequence typing (MLST). While the PFGE patterns tended to cluster within each hospital, sequence types (STs) belonging to the clonal complex 92 (CC92) and the pan-European clonal lineage II (EUII; worldwide clonal lineage 2) were predominant in all hospitals. Of them, ST122 and ST208 were the most common and were found in four of the six hospitals. Isolates belonging to the pan-European clonal lineages I and III were identified in one hospital each. Carbapenemase-encoding genes
bla
OXA-23
and/or IS
Aba1
-
bla
OXA-51-like
were present among the majority of isolates. These findings suggest that carbapenem-nonsusceptible
A. baumannii
isolates found in U.S. hospitals constitute part of the global epidemic driven by CC92, but have unique STs other than ST92, which may be spreading by means of patient transfer between health care facilities within the United States.
Virulence Potential of Escherichia coli Strains Causing Asymptomatic Bacteriuria during Pregnancy
Authors: Lavigne Jean-Philippe , Boutet-Dubois Adeline , Laouini Dorsaf , Combescure Christophe , Bouziges Nicole , Marès Pierre , Sotto Albert
Published: September 2011

We compared the virulence properties of a collection of asymptomatic bacteriuria (ABU)
Escherichia coli
strains to urinary tract infection (UTI) strains isolated from pregnant women in a university hospital over 1 year. The
in vitro
and
in vivo
studies suggest that ABU strains presented a virulence behavior similar to that of strains isolated from cases of cystitis.
Expansion of the Midwestern Focus for Human Granulocytic Anaplasmosis into the Region Surrounding La Crosse, Wisconsin
Authors: Lovrich Steven D. , Jobe Dean A. , Kowalski Todd J. , Policepatil Seema M. , Callister Steven M.
Published: September 2011

Anaplasma phagocytophilum
, the causative agent of human granulocytic anaplasmosis (HGA), shares the same enzootic life cycle as
Borrelia burgdorferi
, the causative agent of Lyme disease. Although La Crosse, WI, is a well-recognized Lyme disease focus with an abundance of
Ixodes scapularis
vector ticks and the first documentation of HGA occurred in patients from northwestern Wisconsin, local transmission of
A. phagocytophilum
has not to date been documented. In this study, we evaluated DNA extracted from 201 ticks captured locally by a real-time PCR that targeted a unique region within
msp2
, and 24 samples (12%) yielded positive results. The PCR also detected
A. phagocytophilum
DNA in blood samples obtained from 53 patients with clinical abnormalities consistent with HGA, and sequencing confirmed that the DNA was recovered from the Ap-ha variant of
A. phagocytophilum
, associated exclusively with human infection. The findings therefore confirmed that the upper Midwestern focus for HGA endemicity now includes the regions immediately surrounding La Crosse, WI. The results also validated the utility of the real-time
msp2
PCR test for confirming acute HGA in the clinical setting.
Characterization of Corynebacterium diphtheriae Isolates from Infected Skin Lesions in the Northern Territory of Australia
Authors: Gordon Claire L. , Fagan Peter , Hennessy Jann , Baird Robert
Published: September 2011

Corynebacterium diphtheriae
is commonly isolated from cutaneous skin lesions in the Northern Territory of Australia. We prospectively assessed 32 recent isolates from infected skin lesions, in addition to reviewing 192 isolates collected over 5 years for toxin status. No isolates carried the toxin gene. Toxigenic
C. diphtheriae
is now a rare occurrence in the Northern Territory.
Escherichia fergusonii Bacteremia in a Diabetic Patient with Pancreatic Cancer
Authors: Lai Chih-Cheng , Cheng Aristine , Huang Yu-Tsung , Chung Kuei-Pin , Lee Meng-Rui , Liao Chun-Hsing , Hsueh Po-Ren
Published: September 2011

Although
Escherichia fergusonii
has been identified for decades, it has rarely been recovered from clinical specimens and its clinical significance remains unclear. We describe a case of
E. fergusonii
bacteremia in a diabetic patient with pancreatic cancer. The isolate was confirmed by three commercial identification systems and 16S rRNA gene sequence analysis. The patient's clinical condition gradually improved, and repeated blood cultures were negative after antibiotic treatment with an
in vitro
active agent (ceftriaxone).
Lethal Mutagenesis of Foot-and-Mouth Disease Virus Involves Shifts in Sequence Space
Authors: Perales Celia , Henry Michel , Domingo Esteban , Wain-Hobson Simon , Vartanian Jean-Pierre
Published: September 2011

Lethal mutagenesis or virus transition into error catastrophe is an antiviral strategy that aims at extinguishing a virus by increasing the viral mutation rates during replication. The molecular basis of lethal mutagenesis is largely unknown. Previous studies showed that a critical substitution in the foot-and-mouth disease virus (FMDV) polymerase was sufficient to allow the virus to escape extinction through modulation of the transition types induced by the purine nucleoside analogue ribavirin. This substitution was not detected in mutant spectra of FMDV populations that had not replicated in the presence of ribavirin, using standard molecular cloning and nucleotide sequencing. Here we selectively amplify and analyze low-melting-temperature cDNA duplexes copied from FMDV genome populations passaged in the absence or presence of ribovirin Hypermutated genomes with high frequencies of A and U were present in both ribavirin -treated and untreated populations, but the major effect of ribavirin mutagenesis was to accelerate the occurrence of AU-rich mutant clouds during the early replication rounds of the virus. The standard FMDV quasispecies passaged in the absence of ribavirin included the salient transition-modulating, ribavirin resistance mutation, whose frequency increased in populations treated with ribavirin. Thus, even nonmutagenized FMDV quasispecies include a deep, mutationally biased portion of sequence space, in support of the view that the virus replicates close to the error threshold for maintenance of genetic information.
Characterization of Wild-Type and Alternate Transcription Termination Signals in the Rift Valley Fever Virus Genome
Authors: Lara Estelle , Billecocq Agnès , Leger Psylvia , Bouloy Michèle
Published: September 2011

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by a phlebovirus of the family
Bunyaviridae
, which affects humans and ruminants in Africa and the Middle East. RFV virus (RVFV) possesses a single-stranded tripartite RNA genome of negative/ambisense polarity. The S segment utilizes the ambisense strategy and codes for two proteins, the N nucleoprotein and the nonstructural NSs protein, in opposite orientations. The two open reading frames (ORFs) are separated by an intergenic region (IGR) highly conserved among strains and containing a motif, 5′-GCUGC-3′, present on the genome and antigenome, which was shown previously to play a role in transcription termination (C. G. Albarino, B. H. Bird, and S. T. Nichol, J. Virol. 81:5246-5256, 2007; T. Ikegami, S. Won, C. J. Peters, and S. Makino, J. Virol. 81:8421-8438, 2007). Here, we created recombinant RVFVs with mutations or deletions in the IGR and showed that the substitution of the motif sequence by a series of five A's inactivated transcription termination at the wild-type site but allowed the transcriptase to recognize another site with the consensus sequence present in the opposite ORF. Similar situations were observed for mutants in which the motif was still present in the IGR but located close to the stop codon of the translated ORF, supporting a model in which transcription is coupled to translation and translocating ribosomes abrogate transcription termination. Our data also showed that the signal tolerated some sequence variations, since mutation into 5′-GCAGC-3′ was functional, and 5′-GUAGC-3′ is likely the signal for the termination of the 3′ end of the L mRNA.
Vaccinia Virus L2 Protein Associates with the Endoplasmic Reticulum near the Growing Edge of Crescent Precursors of Immature Virions and Stabilizes a Subset of Viral Membrane Proteins
Authors: Maruri-Avidal Liliana , Weisberg Andrea S. , Moss Bernard
Published: September 2011

The initial step in poxvirus morphogenesis, the formation of crescent membranes, occurs within cytoplasmic factories. L2 is one of several vaccinia virus proteins known to be necessary for formation of crescents and the only one synthesized early in infection. Virus replication was unaffected when the L2R open reading frame was replaced by L2R containing an N-terminal epitope tag while retaining the original promoter. L2 colocalized with the endoplasmic reticulum (ER) protein calnexin throughout the cytoplasm of infected and transfected cells. Topological studies indicated that the N terminus of L2 is exposed to the cytoplasm with the hydrophobic C terminus anchored in the ER. Using immunogold labeling and electron microscopy, L2 was detected in tubular membranes outside factories and inside factories near crescents and close to the edge or rim of crescents; a similar labeling pattern was found for the ER luminal protein disulfide isomerase (PDI). The phenotype of L2 conditional lethal mutants and the localization of L2 suggest that it participates in elongation of crescents by the addition of ER membrane to the growing edge. Small amounts of L2 and PDI were detected within immature and mature virions, perhaps trapped during assembly. The repression of L2, as well as A11 and A17, two other proteins that are required for viral crescent formation, profoundly decreased the stability of a subset of viral membrane proteins including those comprising the entry-fusion complex. To avoid degradation, these unstable membrane proteins may need to directly insert into the viral membrane or be rapidly shunted there from the ER.