bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonintrusive Investigations Into Life-Size Labyrinth Seal Flow Fields
Authors: Brownell J. B. , Millward J. A. , Parker R. J.
Published: October 2009

Investigations into the thermodynamic processes in labyrinth seal flow fields have been carried out using the nonintrusive optical technique of holographic interferometry. Labyrinth seals in the form of two-dimensional actual size models were used. The types of seal geometry tested reflected those in current use in aerogas turbines, their sizes being typically 10 mm × 20 mm in section with sealing constrictions as small as 0.25 mm. The tests provided a great deal of information that had not previously been available and confirmed several experimental and theoretical results that were not fully understood. The data were obtained in the form of isodensity contour maps. These full field density measurements of the test section flow were analyzed in several ways to provide an insight into the processes occurring within the labyrinth seal. The effects of kinetic energy carry-over upon seal stage performance were dramatically demonstrated in both straight-through and stepped seals. Useful qualitative, as well as quantitative, information regarding the flow field structure could be obtained from the isodensity maps. An indication of particular flow features was obtained at a glance. The optical technique was found to be ideally suited to the investigations and the expected difficulties associated with working in the very small test sections did not arise. The configuration of the optical system ensured that image aberrations were minimized and temporal flow instabilities did not adversely affect the isodensity contour maps. The paper reviews the optical technique and presents a selection of the holographic results along with their interpretation.
Diesel Lube Oils—Fourth Dimension of Diesel Particulate Control
Authors: Springer K. J.
Published: October 2009

Particulate emission control, for the HD diesel engine, has previously been considered a three-dimensional problem involving: (1) combustion of the fuel by the engine, (2) fuel modification, and (3) exhaust aftertreatment. The lube oil contribution may be considered a fourth dimension of the problem. Historically, the heavy-duty engine manufacturer has met emission standards for smoke (1968 to present), CO, HC, and NOx (1974 to present) and particulates (1988 to present) through changes in engine design. This paper uses the allocation method to estimate the reduction in lube oil consumption needed to meet 1991 and 1994 U.S. particulate emission standards. This analysis places the contribution of lube oil as a source of exhaust particulates into prospective with the contributions from fuel sulfur and fuel combustion. An emissions control strategy to meet future regulations is offered in which reductions from fuel modification, combustion improvement, reduced lube oil consumption, and exhaust particulate trap-catalysts are all involved.
Emission Control Technology for Stationary Natural Gas Engines
Authors: Urban C. M. , Dietzmann H. E. , Fanick E. R.
Published: October 2009

This paper summarizes the status of NOx emission control technology for stationary reciprocating natural gas engines. It provides information on most of the known methods of NOx control for natural gas engines that are in use, are being considered for use, or may be considered for use.
Evaluation of Some Factors Controlling DI Diesel Combustion and Exhaust Emissions
Authors: Hunter C. E. , Cikanek H. A. , Gardner T. P.
Published: October 2009

The combined effects of turbocharging, high fuel injection pressure, and reduced oil consumption on diesel exhaust emissions were investigated using a single-cylinder research engine. The influence of these exhaust emission control concepts on particulate composition was determined using a new particulate analysis method. In addition, the dependence of particulate composition on engine load and air utilization was examined using the microfumigation technique. Simultaneous application of these emissions control concepts reduced exhaust particulates by 70 percent. High injection pressure reduced the insoluble component of particulates, while reducing oil consumption and turbocharging the engine lowered both soluble and insoluble particulates. Reductions in oil-derived particulates with increasing engine load were partially attributed to increases in volumetric air utilization. Ninety percent of the lube oil found in exhaust particulates was unburned; however, similar concentrations of unburned and partially oxidized components were observed in fuel-derived particulates.
IGR Solid-State Electrochemical NOx Control for Natural Gas Combustion Exhaust Gases
Authors: Hossain M. S. , Neyman M. , Cook W. J. , Gordon A. Z.
Published: October 2009

Solid-state electrochemical technology, embodied in the IGR process, is used to reduce nitrogen oxides (NOx) to nitrogen and oxygen, and thereby control NOx emissions from natural gas powered engines. The IGR deNOx process is based on solid-state, flow-through, high surface area, porous oxygen ion conductive ceramic electrolytes. Recent bench-scale experiments conducted for the Gas Research Institute have demonstrated NOx reduction in multicomponent gas streams, the inert portion of which simulate natural gas combustion products. The reduction products were analyzed by in situ gas chromatography to verify NOx reduction rates inferred from electrochemical measurements. IGR process advantages compared with existing NOx control technologies are reviewed.
Effects of Ethanol and/or Methanol in Alcohol-Gasoline Blends on Exhaust Emissions
Authors: Bata R. M. , Roan V. P.
Published: October 2009

The effect on exhaust gas emissions (carbon monoxide, CO, hydrocarbons, HC, and aldehydes, CHO) resulting from mixing methanol and/or ethanol with gasoline for automotive fuels has been studied experimentally. Tests were conducted on an OEM four-cylinder engine running at different conditions of equivalence ratio and spark timing. Fuel blends with different percentages of alcohol content and different ratios of methanol to ethanol in the alcohol mixture were tested. Results of this investigation indicated that the presence of either or both of the alcohols in fuel blends significantly reduced the concentration of carbon monoxide in the exhaust emissions (up to 40–50 percent compared to pure gasoline only), with methanol slightly more effective than ethanol. Hydrocarbon emissions were also decreased by increasing the alcohol content of the fuel, with minimum hydrocarbon production occurring at percent alcohol-gasoline blends in conjunction with near-stoichiometric air-fuel ratios. However, aldehyde emissions were found to be markedly higher with alcohol-gasoline blends. The 10 percent alcohol-gasoline blends were found to produce about 50 percent more aldehyde emissions than pure gasoline.
Preinjection—A Measure to Influence Exhaust Quality and Noise in Diesel Engines
Authors: Schulte H. , Scheid E. , Pischinger F. , Reuter U.
Published: October 2009

The combustion noise generated by DI diesel engines can be clearly reduced during both steady-state and transient operation in applying a pilot injection. After optimization, a slight increase in fuel consumption is found in the upper load range. The pilot injection also tends to reduce the NOx emissions. An increase in black smoke emissions is considered to be the main drawback with pilot injection. High-speed Schlieren photographs of injection and combustion phenomena within a pressurized chamber show that the higher black smoke emissions may be due to the combustion of the main injection quantity that occurs in a mixture that is insufficiently prepared and with nearly no delay due to the pilot injection. On the basis of these findings, it is concluded that a high degree of atomization and rapid vaporization of the main injection quantity must be accomplished. To achieve these goals better, a separate injection nozzle for the pilot quantity is preferred to an injection system with a single injection nozzle, providing both the pilot and the main quantity. Therefore, rather simple injection systems with a separate pilot injector can be developed that provide a constant pilot quantity and controlled pilot injection time over the entire engine map.
Investigation of the Effect of Inlet Port on the Flow in a Combustion Chamber Using Multidimensional Modeling
Authors: Taghavi R. , Dupont A.
Published: October 2009

The computational fluid dynamics simulation program KIVA is augmented with a k-ε turbulence model and enhanced geometric capabilities. It is applied to the case of flow in an inlet port and a combustion chamber with a moving valve in order to investigate the effect of inlet flow on the prevailing aerodynamic conditions in the cylinder. The needed initial and time-varying boundary conditions at the upstream section of the intake port are obtained from a one-dimensional acoustic model of the complete single cylinder engine. The three-dimensional flow domain includes an intake port, a combustion chamber, and a moving valve. An internal dynamic rezoning procedure is presented and incorporated in the flow code, which ensures an adequate I, J, K-structured hexahedral mesh when the boundaries of the computation domain are severely distorted, as is the case with a moving valve. Flow computation is carried out from induction TDC to BDC. The resulting velocity and residual burned gas mass fraction fields are then examined and effects due to the geometry of the port and chamber are discussed.
Coal-Fueled Diesels: Systems Development
Authors: McMillian M. H. , Webb H. A.
Published: October 2009

The U.S. Department of Energy (DOE) Office of Fossil Energy has sponsored research in the area of coal-fueled diesel engines since the late 1970s. The program began as an exploratory effort and has grown into a proof-of-concept program that includes several major medium-speed diesel engine manufacturers. Those manufacturers have identified the utility, industrial cogeneration, and transportation markets as areas in which expensive clean distillate fuel may be displaced by low-cost, domestically abundant coal. The development of a coal-fueled diesel engine system will require the parallel development of coal fuels, engine components, wear and emission control system, and a support infrastructure. Because of notable success in earlier projects of the coal-fueled diesel program, the DOE’s Morgantown Energy Technology Center (METC) recently expanded the program with the award of contracts for two 5-year, proof-of-concept project. These major projects will build on the results of past work to complete development of technology for the commercialization of coal-fueled diesel engines. This paper summarizes progress in the DOE program and planned research to overcome technical and economic barriers to that commercialization.
Cooper-Bessemer Coal-Fueled Engine System—Progress Report
Authors: Rao A. K. , Wilson R. P. , Balles E. N. , Mayville R. A. , McMillian M. H. , Kimberley J. A.
Published: October 2009

Single-cylinder engine tests were conducted as part of a long-range effort to develop a technology base for coal-fueled stationary modular power plants based on the Cooper-Bessemer LS Series four-stroke diesel engine. These engine test results established the new state of development for this technology as well as setting priorities for the remaining R&D effort on specific components. The current outlook on the overall economics of coal diesel power is presented, indicating that CWS processing cost dominates the question of economic feasibility. A description of the coal-tolerant fuel injection system development is also given. Wear results indicate that nozzle erosion is the critical element in extending the duration of continuous engine operation. Substantial nozzle wear was observed in just two hours of CWS operation. The ash content of the coal was found to affect the wear rate of the ring set as well as the nozzle tip. Combustion results indicate that the natural gas jet cell is a viable ignition aid and that the variable area poppet nozzle, which lends itself to the use of durable coatings, provides satisfactory engine performance.
Emission Characteristics and Control Technology for Stationary Coal-Fueled Diesel Engines
Authors: Benedek K. R. , Menzies K. T. , Johnson S. A. , Wilson R. P. , Rao A. K. , Schaub F. S.
Published: October 2009

Emissions of primary concern for coal-fueled diesel cogeneration and electric power plants are nitrogen oxides, sulfur dioxide, particulate matter, and aromatic hydrocarbons. In addition, the exhaust particulate size distribution and ash content are relevant to durability of the exhaust valves, turbocharger, and other engine components. This paper summarizes preliminary measurements of “uncontrolled” emissions in the exhaust of a Cooper-Bessemer 33-cm (13-in.) bore, 400 rpm, single-cylinder research engine, operated on “engine-grade” coal-water fuel (0.5 percent ash, 1 percent sulfur, 8 μm mean size coal). Based on these results, we present a preliminary evaluation of emission control options for satisfying hypothetical future emission standards for 2–50 MW power plants. The paper describes coal-diesel component subsystems such as (a) “reburning” for reducing NOx and hydrocarbon emissions, (b) high- and low-temperature injection of calcium sorbents for SO2 capture, and (c) high-temperature bag filters for control of fine particles. The expected performance of a conceptual, integrated control system is presented.
Long-Stroke Pielstick Engine Design Philosophy and Service Result Confirmation
Authors: Chapuy J.-F.
Published: October 2009

Shipowners and diesel engine users are faced with changing fuel costs. The high price of fuel in recent years has pushed SEMT Pielstick to introduce recently a new version of its long-stroke PC engines. SEMT Pielstick worked on basic parameters of engines to reduce fuel consumption. Research was done on supercharging by adapting a new exhaust manifold, by pass arrangement and new turbo-blowers. The combustion chamber parameters have been thoroughly examined regarding firing pressure, stroke-to-bore ratio, and rotational speed. Reliability was checked by designing components of engines according to the state of art and the experience of SEMT Pielstick. The levels of stresses or temperatures were kept the same as for previous engines or even improved in order to give better reliability. This reliability has been confirmed by the results of the first long-stroke Pielstick engines put into service: the PC 20 L installed on the “Sovereign of the Sea” (RCCL) and the PC 40 L, installed on “New Hamanasu,” “New Shirayuri,” and “Muroto.” The oldest of these has operated trouble-free for more than two years. The availability of engines is very good, and service results, such as wear of components, are even better than with the previous standard stroke engine.
A New Concept for Operation of a Pulverized Coal Fired Boiler Using Circulating Fluidized Bed Firing
Authors: Basu P. , Halder P. K.
Published: October 2009

The feasibility of adapting existing pulverized coal fired boilers slated for life extension to circulating fluidized bed firing is examined by considering the case of a 150 MWe tangentially fired pulverized coal boiler. The proposed modifications call for a minimum of change in existing units. Thermal calculations are presented to show how heat absorption in different sections of the converted boiler can be matched to that in the pre-existing pulverized coal fired boiler. Data for two load conditions are presented to identify problems associated with low loads. Fuel flexibility in the converted circulating fluidized bed unit is shown by repeating the thermal calculations for coal washery rejects. It is concluded that the adoption of circulating fluidized bed firing is thermodynamically feasible.
A Method of Evaluating Life Cycle Costs of Industrial Gas Turbines
Authors: Spector R. B.
Published: October 2009

When aeroderivative gas turbines were first introduced into industrial service, the prime criterion for assessing the “relative value” of equipment was derived by dividing the initial (or capital) cost of the equipment by the number of kilowatts produced. The use of “dollars per kilowatt” as an assessment parameter emanated from the utility sector and is still valid providing that the turbomachinery units under consideration possess similar performance features with regard to thermal efficiency. Second-generation gas turbines being produced today possess thermal efficiencies approximately 45 percent greater than those previously available. Thus, a new criterion is required to provide the purchaser with a better “value” perspective to differentiate the various types of turbomachinery under consideration. This paper presents a technique for combining the initial cost of equipment with the costs of fuel consumed, applied labor, and parts to arrive at an assessment parameter capable of comparing the relative merits of varying types of turbomachinery. For simplicity, this paper limits the life cycle cost derivation and discussion to turbogenerator units; however, the principles of this type of life cycle analysis can also be applied to gas turbines in mechanical drive applications and/or combined cycles.
Stabilization of Flow Through Steam-Turbine Control Valves
Authors: Pluviose M.
Published: October 2009

After observing the abrupt variations in flow on an aerodynamic model having the form of a conventional valve, modifications in the basic geometry of the valve are proposed in order to stabilize the flow. The instabilities are almost completely eliminated by introducing an exergy-destructive element into the design of the valve head and seat.
Flyash Adhesion in Simulated Coal-Fired Gas Turbine Environment
Authors: Ahluwalia R. K. , Im K. H. , Wenglarz R. A.
Published: October 2009

A rich-quench-lean subscale turbine combustor has been used to expose specimens to the products of combustion from several beneficiated coal-water fuels. An analytical scheme is formulated to extract sticking coefficients from the measured weight gain data, particle size spectrum, and particle density and composition. The inferred sticking coefficients, appropriate for impaction on the pressure surface, range between 0.0003 and 0.11 and are strong functions of the gas and surface temperatures but rather insensitive to the impact angle. The implications of these results on coal-fired gas turbine operation are discussed.
On the Control Methods of Atmospheric Fluidized Bed Boilers for Power Generation
Authors: Kaya A. , Sternberg H. I.
Published: October 2009

This paper deals with the state of the art of controlling atmospheric fluidized bed steam generators. The emphasis has been placed on multivariable control to provide optimum performance within environmental constraints. A general multivariable model structure is used. The specific model parameters are determined from actual input-output relations (process reactions). Control and optimization methods for commercially implementable controls are presented. The usage of feedback, feed-forward, cascade, and decoupling controls is discussed for the general model. A comparison is made between the proposed controls and those used for conventional boilers to identify areas where particular caution must be exercised in dealing with atmospheric fluidized bed boilers. The implementation and computational capabilities including the current challenges and the needs for further work are presented.
An Autonomous Artificial Designer of Thermal Energy Systems: Part 2—Solution Algorithm
Authors: Kott A. S. , May J. H. , Hwang C. C.
Published: October 2009

A knowledge-based approach to automated conceptual design (flowsheet synthesis) of thermal energy systems with strong interactions between heat/power/chemical transformations is presented. In Part 1, formulation of a thermal design problem is stated in terms of input/output specification, component interaction, feasibility constraints, and penalty function. The problem is then decomposed in inner problems that deal with a set of elementary processes, and outer problems that find a network of components approximating the optimum set of elementary processes. A design state is evaluated using a special form of fundamental equation for steady-state open thermodynamic systems based on a “temperature interval” concept. In Part 2 of this paper, an algorithm is presented. The algorithm makes use of the state evaluation function, transformation operators, and the plausible move operator to search through a space of the design states. A simple closed-cycle gas turbine is employed to illustrate the behavior of the “artificial designer” as it advances from a certain given design to more sophisticated schemes.
Response of Large Turbofan and Turbojet Engines to a Short-Duration Overpressure
Authors: Dunn M. G. , Adams R. M. , Oxford V. S.
Published: October 2009

The influences of thrust setting and overpressure level on engine operating characteristics have been obtained for two different high-thrust engines. The thrust setting was varied from engine-off to take-off rated thrust (TRT) and the overpressure was varied from 6.9 kPa (1.0 psi) to 19.4 kPa (2.8 psi). The specific engines under consideration were the Pratt/Whitney TF33 low bypass ratio turbofan and the Pratt/Whitney J57 turbojet. The experimental results suggest that overpressure has little influence on either the HP compressor speed or the exhaust gas total temperature. However, the magnitude of the overpressure has a large influence on turbine exhaust total pressure and on the inlet casing and the diffuser casing radial displacements. The J57 turbine casing was significantly influenced by the overpressure, whereas the TF33 turbine casing was relatively insensitive. The J57 inlet casing radial displacement was noticeably greater than the corresponding turbofan displacement. Even though the component radial displacements for the TF33 exceeded the steady-state red-line limit by more than 300 percent, the engine did not sustain any permanent damage. The J57 did, however, experience an internal rub at an overpressure of about 14.5 kPa (2.1 psi).
Molecular-to-Large-Scale Heat Transfer With Multiphase Interfaces: Current Status and New Directions
Authors: Manglik Raj M. , Jog Milind A.
Published: October 2009

The scientific understanding of multiphase interfaces and the associated convective mass, momentum, and heat transport across and along their boundaries, provide the fundamental underpinnings of the advancement of boiling heat transfer, two-phase flows, heat pipes, spray cooling, and droplet-film coating, among many other engineering applications. Numerous studies have tried to characterize the interfacial behavior and model their mechanistic influences either directly or implicitly via parametric experimental investigations and/or simulations. The goal of advancing our understanding as well as developing generalized, perhaps “universal,” and more accurate phenomenological or mechanistic correlations, for predicting mass, momentum, and heat transfer, continues to engage the worldwide research community. A collection of some such current investigations that are representative of both basic and applied issues in the field is presented in this special issue of the Journal of Heat Transfer.
A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part II: Experimental Validation
Authors: Wu Wen , Jones Barclay G. , Newell Ty A.
Published: October 2009

A mechanistic model for the boiling heat flux prediction proposed in Part I of this two-part paper (2009, “A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part I: Model Development,” ASME J. Heat Transfer, 131, p. 121013) is verified in this part. In the first step, the model is examined by experiments conducted using R134a covering a range of pressures, inlet subcoolings, and flow velocities. The density of the active nucleation sites is measured and correlated with critical diameter Dc and static contact angle θ. Underlying submodels on bubble growth and bubble departure/lift-off radii are validated. Predictions of heat flux are compared with the experimental data with an overall good agreement observed. This model achieves an average error of ±25% for the prediction of R134a boiling curves, with the predicted maximum surface heat flux staying within ±20% of the experimentally measured critical heat flux. In the second step, the model is applied to water data measured by McAdams et al. (1949, “Heat Transfer at High Rates to Water With Surface Boiling,” Ind. Eng. Chem., 41(9), pp. 1945–1953) in vertical circular tubes. The consistency suggests that the application of this mechanistic model can be extended to other flow conditions if the underlying submodels are appropriately chosen and the assumptions made during model development remain valid.
Sequential Processing of Lexical, Grammatical, and Phonological Information Within Broca’s Area
Authors: Sahin Ned T. , Pinker Steven , Cash Sydney S. , Schomer Donald , Halgren Eric
Published: October 2009

Seeing the Brain's One, Two, Three

Taking advantage of the rare opportunity to record neuronal activity in the human brain using intracranial electrodes,

Sahin
et al.

(p.
445
; see the Perspective by

Hagoort and Levelt

) document the spatial and temporal pattern of neuronal populations within Broca's area as patients thought of a single word, changed its tense (for verbs) or number (for nouns), and articulated the word silently. For these three stages, they detected activity at 200, 320, and 450 milliseconds, moving in a caudal to rostral direction. These data fit neatly within the roughly 600 milliseconds required for the onset of speech and map the distinct neural computations within an area of the brain, known for almost a century and a half, as important for the production of language.
Balancing Innovation and Access: Patent Challenges Tip the Scales
Authors: Higgins Matthew J. , Graham Stuart J. H.
Published: October 2009

Development of new but costly pharmaceuticals is put at risk by U.S. law that emboldens generics competition.
The Packing of Granular Polymer Chains
Authors: Zou Ling-Nan , Cheng Xiang , Rivers Mark L. , Jaeger Heinrich M. , Nagel Sidney R.
Published: October 2009

Like Beads on a String

The optimal packing of spheres, and the somewhat lower densities obtained in the compaction of granular materials are well studied problems. What is less clear is what happens when the spheres are connected, as in the case of polymeric materials—often represented by connected sphere models.

Zou
et al.

(p.
408
; see the Perspective by

Reichhardt and Lopatina
)

examined the packing of chains of metal beads commonly used for securing bathroom drain plugs or for raising or lowering window blinds. Both the length of the chains, and whether they were linear or looped, influenced the overall packing density. Jamming the chains together captured the key physics of the glass transition of polymeric materials.
Generation of Functional Ventricular Heart Muscle from Mouse Ventricular Progenitor Cells
Authors: Domian Ibrahim J. , Chiravuri Murali , van der Meer Peter , Feinberg Adam W. , Shi Xi , Shao Ying , Wu Sean M. , Parker Kevin Kit , Chien Kenneth R.
Published: October 2009

A Fix to the Heart

Regenerative cardiovascular medicine is a promising avenue for therapeutic application in advanced heart failure. Although clinical trials have suggested some limited benefits in cell transplantation therapy, robust cardiac muscle formation is lacking.

Domian
et al.

(p.
426
) examined the developmental processes in normal mature cardiac muscle. A two-color murine reporter system was used to isolate committed ventricular progenitors, which were then used to build functional force-generating cardiac tissue. Such combinations of tissue engineering and stem cell biology may eventually lead to cardiac regenerative therapy.
Fast Synaptic Subcortical Control of Hippocampal Circuits
Authors: Varga Viktor , Losonczy Attila , Zemelman Boris V. , Borhegyi Zsolt , Nyiri Gábor , Domonkos Andor , Hangya Balázs , Holderith Noémi , Magee Jeffrey C. , Freund Tamás F.
Published: October 2009

Subcortical Network Regulation

Subcortical neuromodulatory centers dominate the motivational and emotional state–dependent control of cortical functions. Control of cortical circuits has been thought to involve a slow, diffuse neuromodulation that affects the excitability of large numbers of neurons relatively indiscriminately.

Varga
et al.

(p.
449
) describe a form of subcortical control of cortical information processing whereby strong, spatiotemporally precise excitatory input from midbrain serotonergic neurons produces a robust activation of hippocampal interneurons. This effect is mediated by a synaptic release of both serotonin and glutamate and impacts network activity patterns.
Direct Evidence for Spinal Cord Involvement in Placebo Analgesia
Authors: Eippert Falk , Finsterbusch Jürgen , Bingel Ulrike , Büchel Christian
Published: October 2009

Functional magnetic resonance imaging of the human spinal cord reveals a mechanism for placebo analgesia.
Feeding the Clock
Authors: Suter David M. , Schibler Ueli
Published: October 2009

A nutrient-responsive enzyme regulates the stability of a circadian clock component.
The Speaking Brain
Authors: Hagoort Peter , Levelt Willem J. M.
Published: October 2009

Recordings of electrical activity in the human brain reveal the fine-tuned, stepwise neuronal processing of language and speech.
The Big Gamble in the Saudi Desert
Authors: Mervis Jeffrey
Published: October 2009

King Abdullah University of Science and Technology is betting that generous funding and great facilities will attract the talent it will need to become a top-ranked institution.
Fetal Cells Again?
Authors: Holden Constance
Published: October 2009

Despite past failures and growing skepticism about cell therapy in general, scientists once again plan to test fetal cell transplants on Parkinson's disease.
A Guru of the Green Revolution Reflects on Borlaug's Legacy
Authors: Bagla Pallava
Published: October 2009

Agricultural scientist Monkombu Sambasivan Swaminathan worked with Norman Borlaug for nearly half a century and spoke with
Science
about the Nobel laureate's contributions to South Asia.
Prevalence of Human Papillomavirus 16 and 18 Neutralizing Antibodies in Prenatal Women in British Columbia
Authors: Krajden Mel , Karunakaran Karuna , So Stacy , Palefsky Joel M. , Sharma Rachna , Cook Darrel , Yu Amanda , Chow Ron , Dobson Simon , Ogilvie Gina S. , Petric Martin
Published: October 2009

Human papillomavirus (HPV) type 16 and 18 neutralizing antibody (NAb) titers were measured in 1,020 prenatal women in British Columbia aged 15 to 39. HPV 16 and 18 NAbs were detected in 183/1,020 (17.9%) and 97/1,020 (9.5%), respectively, and 39 (3.8%) had NAbs to both types. Titers were similar across age strata.
Detection of Asymptomatic Antigenemia in Pigs Infected by Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) by a Novel Capture Immunoassay with Monoclonal Antibodies against the Nucleocapsid Protein of PRRSV
Authors: Cai Jian-Piao , Wang Ya-Di , Tse Herman , Xiang Hua , Yuen Kwok-Yung , Che Xiao-Yan
Published: October 2009

Routine surveillance for porcine reproductive and respiratory syndrome virus (PRRSV) infections is crucial for the epidemiological control of this disease. Antibody tests are widely used but cannot differentiate between vaccination and reinfection. We developed a PRRSV antigen capture enzyme-linked immunosorbent assay (ELISA) using well-characterized monoclonal antibodies (MAbs) raised against the nucleocapsid (N) protein of North American and European PRRSV. This antigen assay detected purified N protein from both genotypes at levels as low as 0.4 and 0.8 ng, respectively. The specificity and sensitivity of the N antigen assay were evaluated with ground lung tissues from 8 PRRSV-infected and 16 healthy swine, and culture supernatants from six PRRSV isolates as well as other swine viruses were confirmed by reverse transcriptase PCR (RT-PCR). Antigen assays were positive in all eight infected tissues and with six different PRRSV isolates, with no false positives among healthy tissues and other swine viruses (i.e., pseudorabies and foot and mouth disease viruses). A number of sera, field collected from 466 vaccinated and asymptomatic pigs in Guangdong, China, between 2008 and 2009, tested positive by the N antigen assay (12.45%), RT-PCR (15.02%), and a commercial test for antibodies against PRRSV (78.97%). Of the 466 sera, 47 were positive by both antigen and RT-PCR tests, 11 by antigen test only, and 23 by RT-PCR only; the two assays had an overall agreement of 92.7%, indicating a significant percentage of active PRRSV in asymptomatic pigs despite previous immunization. These findings suggest that the antigen assay is a valuable field tool for the epidemiological control of PRRSV that can be used for rapid screening, particularly in asymptomatic animals.
Immune Response and Viral Persistence in Indian Buffaloes (
Bubalus bubalis
) Infected with Foot-and-Mouth Disease Virus Serotype Asia 1
Authors: Maddur Mohan S. , Kishore Subodh , Gopalakrishna S. , Singh Nem , Suryanarayana V. V. , Gajendragad Mukund R.
Published: October 2009

Despite their potential role in the spread of foot-and-mouth disease (FMD), the immune response and viral persistence in FMD virus (FMDV)-infected Indian buffaloes (
Bubalus bubalis
) have been unexplored. We found similar kinetics of neutralizing antibody responses in the sera and secretory fluids of buffaloes following experimental FMDV Asia 1 infection, but the lymphocyte-proliferative response in infected buffaloes was of low magnitude. Despite inducing a significant systemic and secretory immune response, viral persistence seems to be a common outcome in buffaloes following FMDV Asia 1 infection, which is associated with a weak cellular immune response.
Receptor Recognition of and Immune Intracellular Pathways for
Veillonella parvula
Lipopolysaccharide
Authors: Matera Giovanni , Muto Valentina , Vinci Maria , Zicca Emilia , Abdollahi-Roodsaz Shahla , van de Veerdonk Frank L. , Kullberg Bart-Jan , Liberto Maria Carla , van der Meer Jos W. M. , Focà Alfredo , Netea Mihai G. , Joosten Leo A. B.
Published: October 2009

Veillonella parvula
is an anaerobic gram-negative coccus that is part of the normal flora of the animal and human mouth and gastrointestinal and genitourinary tracts. Oral
V. parvula
is involved in the development of early periodontal disease as well as different types of serious infections. Present data on molecular mechanisms responsible for innate immune response against
Veillonella
are very scanty. The aim of this study was to investigate the Toll-like receptor (TLR) pathways responsible for
V. parvula
lipopolysaccharide (LPS) and to identify the intracellular pathways induced by this recognition.
V. parvula
LPS stimulated tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) release in human peripheral blood mononuclear cells (PBMC) in a dose-dependent manner. Pretreatment of cells with a TLR4 antagonist significantly reduced TNF-α and IL-6 production in PBMC stimulated with either
Veillonella
or
Escherichia coli
LPS. However,
V. parvula
LPS was 10- to 100-fold less active than
E. coli
LPS for cytokine induction. TNF-α, IL-1β, IL-6, and IL-10 were released in wild-type and TLR2
−/−
, but not TLR4
−/−
, mouse macrophage cultures.
V. parvula
LPS was able to activate the human PBMC p38 mitogen-activated protein kinase (MAPK). A specific p38 MAPK inhibitor strongly inhibited
V. parvula
LPS-induced TNF-α, IL-1β, IL-6, and IL-10. In conclusion,
V. parvula
LPS is able to induce cytokine production in both human and murine in vitro models, although it is less effective than
Enterobacteriaceae
LPS.
V. parvula
LPS-stimulated cytokine induction, as well as p38 MAPK activation, are TLR4-dependent features.
International External Quality Assurance for Laboratory Diagnosis of Diphtheria
Authors: Neal S. E. , Efstratiou A.
Published: October 2009

The diphtheria surveillance network (DIPNET) encompassing National Diphtheria Reference Centers from 25 European countries is a Dedicated Surveillance Network recognized by the European Commission. A key DIPNET objective is the quality assessment of microbiological procedures for diphtheria across the European Union and beyond. A detailed questionnaire on the level of reference laboratory services and an external quality assessment (EQA) panel comprising six simulated throat specimens were sent to 34 centers. Twenty-three centers are designated National Diphtheria Reference Centers, with the laboratory in the United Kingdom being the only WHO Collaborating Centre. A variety of screening and identification tests were used, including the cysteinase test (20/34 centers), pyrazinamidase test (17/34 centers), and commercial kits (25/34 centers). The classic Elek test for toxigenicity testing is mostly used (28/34 centers), with variations in serum sources and antitoxin concentrations. Many laboratories reported problems obtaining Elek reagents or media. Only six centers produced acceptable results for all six specimens. Overall, 21% of identification and 13% of toxigenicity reports were unacceptable. Many centers could not isolate the target organism, and most found difficulties with the specimens that contained
Corynebacterium striatum
as a commensal contaminant. Nineteen centers generated either false-positive or negative toxigenic results, which may have caused inappropriate medical management. The discrepancies in this diphtheria diagnostics EQA alarmingly reflect the urgent need to improve laboratory performance in diphtheria diagnostics in Europe, standardize feasible and robust microbiological methods, and build awareness among public health authorities. Therefore, DIPNET recommends that regular workshops and EQA distributions for diphtheria diagnostics should be supported and maintained.
Oligonucleotide-Gold Nanoparticle Networks for Detection of
Cryptosporidium parvum
Heat Shock Protein 70 mRNA
Authors: Javier David J. , Castellanos-Gonzalez Alejandro , Weigum Shannon E. , White A. Clinton , Richards-Kortum Rebecca
Published: October 2009

We report on a novel strategy for the detection of mRNA targets derived from
Cryptosporidium parvum
oocysts by the use of oligonucleotide-gold nanoparticles. Gold nanoparticles are functionalized with oligonucleotides which are complementary to unique sequences present on the heat shock protein 70 (HSP70) DNA/RNA target. The results indicate that the presence of HPS70 targets of increasing complexity causes the formation of oligonucleotide-gold nanoparticle networks which can be visually monitored via a simple colorimetric readout measured by a total internal reflection imaging setup. Furthermore, the induced expression of HSP70 mRNA in
Cryptosporidium parvum
oocysts via a simple heat shock process provides nonenzymatic amplification such that the HSP70 mRNA derived from as few as 5 × 10
3
purified
C. parvum
oocysts was successfully detected. Taken together, these results support the use of oligonucleotide-gold nanoparticles for the molecular diagnosis of cryptosporidiosis, offering new opportunities for the further development of point-of-care diagnostic assays with low-cost, robust reagents and simple colorimetric detection.
Heteroresistance to Meropenem in Carbapenem-Susceptible
Acinetobacter baumannii
Authors: Ikonomidis Alexandros , Neou Evangelia , Gogou Vassiliki , Vrioni Georgia , Tsakris Athanassios , Pournaras Spyros
Published: October 2009

The characteristics of carbapenem heteroresistance were studied in 14 apparently carbapenem-susceptible
Acinetobacter baumannii
isolates. The MICs for carbapenems were determined, and the isolates were genotyped by pulsed-field gel electrophoresis (PFGE) and sequence typing (ST). Population analysis, testing of the stability of the heteroresistant subpopulations, and time-killing assays were performed. The agar dilution MICs of both imipenem and meropenem for the native isolates ranged from 0.25 to 4 mg/liter. The isolates belonged to nine PFGE types and exhibited seven ST allelic profiles. Population analysis revealed subpopulations that grew in the presence of imipenem at concentrations of up to 8 mg/liter and meropenem at concentrations of up to 32 mg/liter. The meropenem-heteroresistant subpopulations of 11 isolates exhibited stable resistance with MICs that ranged from 16 to >32 mg/liter; their PFGE profiles were identical to those of the native isolates. Time-kill assays with meropenem revealed less pronounced killing for 10 isolates. These findings indicate that meropenem pressure can produce meropenem-heteroresistant subpopulations that might subsequently select for highly resistant strains.
Molecular Diagnostics of Hemorrhagic Fever with Renal Syndrome during a Dobrava Virus Infection Outbreak in the European Part of Russia
Authors: Dzagurova Tamara K. , Klempa Boris , Tkachenko Evgeniy A. , Slyusareva Galina P. , Morozov Vyacheslav G. , Auste Brita , Kruger Detlev H.
Published: October 2009

A large outbreak of hemorrhagic fever with renal syndrome (HFRS) occurred in the winter of 2006-2007 in a region southeast of Moscow in Central European Russia. Of the 422 patients with HFRS investigated in this study, 58 patients were found to be infected by Puumala virus, whereas as many as 364 were infected by Dobrava-Belgrade virus (DOBV). Early serum samples from 10 DOBV-infected patients were used for nucleic acid amplification, which was successful for 5 patients. Molecular analyses demonstrated that the causative hantavirus belongs to the DOBV-Aa genetic lineage, which is carried by the striped field mouse (
Apodemus agrarius
) as the natural reservoir host. Neutralization assays with convalescent-phase sera from these patients confirmed infection by DOBV-Aa; related viruses, such as the Dobrava-Slovenia virus (DOBV-Af) and the Dobrava-Sochi virus (DOBV-Ap), were neutralized at lower efficiencies. The clinical courses of the 205 patients enrolled in the study were found to be mostly mild to moderate; however, an unexpectedly high fraction (27%) of patients exhibited severe illness. One patient died from kidney failure and showed symptoms of generalized subcutaneous hemorrhage. The results provide molecular, serodiagnostic, and clinical evidence that DOBV-Aa is a common pathogen in East Europe that causes large outbreaks of HFRS.
New Multiplatform Computer Program for Numerical Identification of Microorganisms
Authors: Flores Oscar , Belanche Lluís A. , Blanch Anicet R.
Published: October 2009

The classification of bacteria by using genomic methods or expensive biochemical-based commercial kits is sometimes beyond the reach of many laboratories that need to perform numerous classifications of unknown bacterial strains in a fast, cheap, and reliable way. A new computer program,
Identax
, for the computer-assisted identification of microorganisms by using only results obtained from conventional biochemical tests is presented.
Identax
improves current microbial identification software and provides a multiplatform and user-friendly program. It can be executed from any operating system and can be downloaded without any cost from the
Identax
website (
www.identax.org
).
Clinical Performance of Human Papillomavirus E6 and E7 mRNA Testing for High-Grade Lesions of the Cervix
Authors: Cattani Paola , Zannoni Gian Franco , Ricci Caterina , D'Onghia Sara , Trivellizzi Ilaria Nausica , Di Franco Aldo , Vellone Valerio G. , Durante Maria , Fadda Giovanni , Scambia Giovanni , Capelli Giovanni , De Vincenzo Rosa
Published: October 2009

Infection with high-risk (HR) human papillomavirus (HPV) is the major cause of cervical cancer. However, relatively few infections progress to malignant disease. Progression to malignancy requires the overexpression of the E6 and E7 genes in the integrated HPV genome. It follows that the E6 and E7 transcripts could be useful markers of disease progression. The study presented here tests this possibility, using data from colposcopy and from cytological and histological tests to compare RNA assays for the E6 and E7 genes with DNA testing. A total of 180 women underwent colposcopy, cytology, and biopsy of suspected lesions (143 cases). Cervical brush specimens were analyzed for HPV DNA and for E6 and E7 mRNA. DNA from HR HPV was found in 57.8% of the specimens; E6 and E7 transcripts were found in 45%. The rates of detection of HPV DNA and of E6 and E7 transcripts were 33.3% and 25%, respectively, for specimens with normal findings; 51.4% and 31.9%, respectively, for specimens with cervical intraepithelial neoplasia grade 1 (CIN1); and 61.1% and 44.2% for specimens with CIN2, respectively. All specimens with CIN3 and 95.5% of specimens from patients with squamous cell carcinoma were positive by both assays. Thirty-seven patients with normal colposcopy findings did not undergo biopsy. HPV DNA and mRNA transcripts were found in 32.4% and 18.9% of these cases, respectively. Comparisons with cytological tests produced similar results. Overall, the mRNA tests showed a higher specificity than the DNA tests for high-grade lesions (72.7% and 56.2%, respectively) and a higher positive predictive value (59.3% and 49.0%, respectively). These findings suggest that mRNA assays could be more powerful than DNA testing for predicting the risk of progression and offer a strong potential as a tool for triage and patient follow-up.
Enhanced Viral Etiological Diagnosis of Respiratory System Infection Outbreaks by Use of a Multitarget Nucleic Acid Amplification Assay
Authors: Wong Sallene , Pabbaraju Kanti , Lee Bonita E. , Fox Julie D.
Published: October 2009

A study was undertaken to assess the utility of the xTAG respiratory viral panel (RVP) for enhanced laboratory investigation of respiratory outbreaks. Specimens (
n
= 1,108) from 244 suspected respiratory virus outbreaks in 2006 and 2007 in Alberta, Canada, were included in the study. Testing by direct fluorescent antigen detection (DFA) and various in-house nucleic acid amplification tests (NATs) for common respiratory viruses provided an etiological diagnosis in 177 outbreaks (72.5%), with 524 samples testing positive (47.3%) for a respiratory virus. Two hundred samples from 51 unresolved outbreaks were further tested by RVP retrospectively. Fifty-eight samples from 30 unresolved outbreaks had a respiratory virus detected by RVP (47 picornavirus-positive, 9 coronavirus-positive, and 2 influenza virus A-positive samples). Overall, detection of a viral etiological agent was achieved in 90.8% of outbreaks using a combination of DFA, NATs, and RVP. Use of RVP enhances the laboratory investigation of respiratory virus outbreaks and facilitates appropriate patient and outbreak management.