bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen Generation Can Reduce New Plant Design and Building Costs
Authors: Wolff David E. , Bailey William , Skoczylas Tom
Published: February 2014

Large electric power plant generators typically use gaseous hydrogen to remove heat from the generator windings and deliver the heat to the cooling water. Hydrogen is used in a closed cycle, and only a modest amount of makeup hydrogen is used daily to make up for hydrogen losses — typically about 300 to 700 scf/d. The range of hydrogen usage depends on several factors. In addition to hydrogen used for makeup, all power plants using hydrogen-cooled generators must plan for hydrogen supply to re-gas a generator after the generator has been degassed. Typical generator re-gas quantities are in the range of 15× the daily makeup amount, and must be available in a short period of time. Thus a generator which might require 300 to 700 scf of hydrogen over 24 hours for daily makeup may require 4500 to 10,500 scf of hydrogen in just a few hours for re-gas. The re-gas hydrogen is added back to the generator as quickly as the re-gas process allows — typically over 3–5 hours — so that an out-of-service generator can be brought online and producing revenue again. Hydrogen for power plant generator cooling can be supplied either through hydrogen delivered to the plant from a remote source in gaseous or liquid form, or can be made at the plant using an on-site hydrogen generator. Makeup hydrogen and re-gas hydrogen do not necessarily require the same source of hydrogen — because the requirements of re-gas hydrogen are very different from the requirements of makeup hydrogen, it may be more efficient to use two different approaches. On-site hydrogen generation for power plant hydrogen supply is widespread in the developing world, and is beginning to displace delivered hydrogen as the preferred approach in the U.S., Canada and Europe. Outside U.S., Canada and Europe, there may be no delivery infrastructure for hydrogen manufacture and delivery to the plant — a hydrogen-cooled power plant may need to take care of its own hydrogen needs to ensure that the plant can be operated. In the U.S., Canada and Europe hydrogen deliveries are available, but on-site generated hydrogen is gaining acceptance because it reduces costs and operational complexity, and improves safety. This paper will review several cases where on-site hydrogen generation has been used to reduce the cost of design, construction and operation of newly built power plants, both in the U.S., Canada and Europe and in areas where hydrogen is far less available.
Waste / Low Quality Heat Recovery and Utilization With Low Temperature Economizers
Authors: Preston John M. , Watson W. Reid , Jones Charles B.
Published: February 2014

Modern combustion steam-electric plants are designed to recover as much heat as economically feasible from the combustion products. As a part of the continuing effort by utilities to increase plant efficiency, extracting low quality heat from the flue gas stream prior to discharge through the stack to the environment has become economically attractive. “Economic feasibility” is strongly dependent on the cost of the fuel as well as quality of the heat recovered. The economic feasibility of deploying low-temperature economizers to cool flue gas from coal-fired steam-electric plants to a temperature well below the sulfuric acid mist dew point is not commonly practiced but could have a number of salutary effects on unit operations including reduction in fuel use, reduction in water, reduction in fly ash resistivity upstream of cold-side electrostatic precipitators and enhanced mercury oxidation/capture.

Using a theoretical 600 MW (nominal) coal fired facility an additional 30.8 MW of electrical output is available with the installation of a Low Temperature Economizer. This represents a 1% improvement in the plant heat rate with an attractive payback period. The components required for this heat recovery sub-system are readily available and the technology has matured to a point where uncertainties are minimized.

In addition to improving the operation of the plant, Low Temperature Economizer can reduce emissions of SOx, NOx, Hg, PM and CO2. In a difficult regulatory environment reducing emissions while increasing plant performance is extremely beneficial. Furthermore Low Temperature Economizer lowers the volume of scrubber water required.

Cooling the flue gas leaving the air heater below the acid mist dew point is not commonly practiced. The corrosion potential of the condensed sulfuric acid is a major materials selection/maintenance challenge as is the potential for gas-side fouling of the heat exchange surface with fly ash.
Economic Design of Hybrid Wet-Dry Cooling Systems
Authors: Card R. W.
Published: February 2014

A hybrid wet-dry cooling system can be designed for a large combined-cycle power plant.

A well-designed hybrid cooling system will provide reasonable net generation year-round, while using substantially less water than a conventional wet cooling tower. The optimum design for the hybrid system depends upon climate at the site, the price of power, and the price of water. These factors vary on a seasonal basis.

Two hypothetical power plants are modeled, using state-of-the-art steam turbines and hybrid cooling systems. The plants are designed for water-constrained sites incorporating typical weather data, power prices, and water prices.

The principles for economic designs of hybrid cooling systems are demonstrated.
Investigation of the Prediction Correlations for the Flow Through Rotating Orifices in the Gas Turbine Secondary Air Flow System
Authors: Prabhudharwadkar Deoras , Dweik Zain , Subramani A. , Krishnan R. Murali
Published: February 2014

The secondary air flow system of a gas turbine cools and seals those parts of the turbine which would otherwise be exposed to the high temperatures, resulting in their life reduction or even failures. At the same time, excessive secondary air flow hinders the performance of the engine. Accurate analysis of the secondary system is therefore necessary to safeguard the reliable design of the engine and accurate life predictions. The secondary system is analyzed through the flow network analysis which comprises of chambers or cavities connected through flow passages or restrictions. There are significant number of locations where the air passes through stationary or rotating holes, e.g., the pre-swirl nozzles and the turbine blade receiver holes respectively.

The accuracy of the flow prediction depends on the accuracy of the orifice discharge coefficient. This paper provides a detailed assessment of the available discharge coefficient correlations. The discharge coefficient has been found to be dependent on the geometric parameters (viz., length, inlet radius, chamfer), and the amount of cross-flow at the orifice entrance. The cross-flow may result from the relative tangential velocity between the orifice and the air or the inclination of the inlet flow with respect to the orifice axis. In this study, it was found that the discharge coefficient correlations provide similar predictions for flows without any cross-flow. However, significant deviations are seen in the predictions for the cases involving cross-flow. To identify the most accurate correlation for secondary flow application, a thorough assessment was performed using the static and the rotating test data available in the literature. In addition to the comparison using available experimental data, a CFD study was performed to independently assess the correlations. This exercise led to the identification of the most suitable correlation for our application.
Status and Future Development for Nuclear Cogeneration System GTHTR300C
Authors: Yan Xing L. , Sato Hiroyuki , Ohashi Hirofumi , Tachibana Yukio , Kunitomi Kazuhiko
Published: February 2014

GTHTR300C is a small modular reactor based on a 600 MWt high temperature gas reactor (HTGR) and intended for a number of cogeneration applications such as process heat supply, hydrogen production, steelmaking, desalination in addition to power generation. The basic design has been completed by JAEA together with Japanese heavy industries. The reactor design and key plant technologies have been validated through test reactor and equipment verification. Future development includes demonstration programs to be performed on a 50 MWt system HTR50S. The demonstration programs are implemented in three steps. In the first step, a base commercial plant for heat and power is to be constructed of the same fuel proven in JAEA’s successful 950°C, 30 MWt HTGR test reactor and a conventional steam turbine such that the construction can readily proceed without major development requirement and risk. Beginning in the second step, a new fuel presently being developed at JAEA is expected to be available. With this fuel, the core outlet temperature is raised to 900°C for purpose of demonstrating more efficient gas turbine power generation and high temperature heat supply. Added in the final step is a thermochemical process to demonstrate nuclear-heated hydrogen production via water decomposition. A licensing approach to coupling high temperature industrial process to nuclear reactor will be developed. The designs of GTHTR300C and HTR50S will be presented and the demonstration programs will be described.
Experimental Studies on New High Efficient S-Shaped Shaft Extension Tubular Pump System
Authors: Liu Chao , Yang Fan
Published: February 2014

Based on the principle of the minimum resistance, the optimum design of suction and discharge passages of pump system was made with CFD numeric simulation. Two sets of new S-shaped, façade and plane, shaft extension tubular pump were developed. A physical model experimental research on energy performance, cavitation performance and runaway characteristics of the pump model system has been conducted on the high precision hydraulic machinery test stand. The results show that the highest efficiency of the plane S-shaped extension pump system is 83.32% at the blade angle −4°, the maximum difference value of pump system and pump is 6.02% at the optimum operating condition. The highest efficiency of the facade S-shaped extension pump system is 83.55% at the blade angle −2°. Two sets of S-shaped shaft extension tubular pump systems have significant advantages of high efficiency and energy-saving.
Utilization of CFD to Reduce NOx, Improve Efficiency and Reliability of a PC Boiler
Authors: Berg Lawrence D. , Goldring John P. , Sharp Guy
Published: February 2014

Ferrybridge “C” Power station is owned by SSE and has 2,000 MWe of generating capacity and utilizes pulverized coal as its fuel source. Originally commissioned in 1966, it was designed to burn local Yorkshire coal, but currently uses a varied supply from South African to Russian coals. In order to meet the Large Combustion Plant Directive (LCPD) emission requirements, starting in the late 1990’s, the plant was first retrofit with low NOx burners and later with a Boosted Over Fire Air (BOFA) system. These modifications allowed the plant to achieve compliant NOx operation of 500 mg/Nm3, but had the unintended side effects of high unburned carbon in the fly ash (CIA) and operational problems. This paper discusses some of the site investigations, analysis and modifications that were accomplished on the plant to address these issues. In the process of attending to these issues, NOx emissions of less than 300 mg/Nm3 have been demonstrated, on the Unit, a significant reduction from 500 mg/Nm3. With the Industrial Emissions Directive (IED) regulations looming, and a further reduction to 200mg/Nm3 required, these reductions improve the options the plant has in maintaining compliant operations.
Use of Condensing Heat Exchangers in Coal-Fired Power Plants to Recover Flue Gas Moisture and Capture Air Toxics
Authors: Levy Edward , Bilirgen Harun , Charles Joshua , Ness Mark
Published: February 2014

Heat exchangers, which cool boiler flue gas to temperatures below the water vapor dew point, can be used to capture moisture from flue gas and reduce external water consumption for power plant operations. At the same time, thermal energy removed from the flue gas can be used to improve unit heat rate. Recent data also show that emissions of air toxics from flue gas would be reduced by use of condensing heat exchangers. This paper describes results from a slip stream test of a water cooled condensing heat exchanger system at a power plant with a lignite-fired boiler. The flue gas which flowed through the heat exchangers had been extracted from a duct downstream of the electrostatic precipitator. Measurements were made of flue gas and cooling water temperatures, flue gas water vapor concentrations, and concentrations of elemental and oxidized Hg at the inlet and exit of the heat exchanger system. Condensed water was also collected and analyzed for concentrations of H2SO4 and HCl. Results on the effects of the condensing heat exchanger operating conditions on oxidation and capture of Hg and on the capture of sulfuric and hydrochloric acids are described.
Optimization of Design and Operation of a Combined Heat and Power Plant, by Use of a 1D-Physical Model
Authors: Deneux Olivier , Péchiné Bruno , Fouquet Manon
Published: February 2014

Many industries require heat or cold in their production plants. To meet these needs, companies usually equip their generation sites with combined heat and power plants.

The goal of the present study is to build an accurate 1D-physical model of a cogeneration plant and to use it to optimize the plant from design phase to operation phase. The study shows that using the Modelica language and a library of plant components such as ThermoSysPro are adequate for building a modular 1D-physical model. Once the model built, optimization tools were used for optimizing both design (component specification for allowing maximized profit and minimized investment) and operation (loads of turbines and engines for maximized profit).

Physical models may therefore be used for an optimization purpose. Moreover the developed tools may prove useful for engineers operating combined heat and power plants for monitoring and optimizing purposes.
Scaling Test Data to Predict Performance
Authors: Burke Jacqueline , Hunter Andrew , Nyquist Roger , Andrews Mike
Published: February 2014

In the aerodynamic design of centrifugal compressors, it is possible to scale test data to predict the geometry (impeller diameter and tip width) necessary for a stage to meet a certain performance. There is not, however, a standard industry scaling method. The important points on the performance curve to consider in the scaling process are the scaling point, the surge point and the choke point. Choosing a scaling point is not objective and generally impellers are tested as part of a multistage machine where one stage is controlling, so the true surge and choke points are rarely known; these details make it difficult to depend on scaling alone for impeller design. Thus, impellers are often designed with one-dimensional (1-D) wheel sizing programs that rely on inexact slip and blockage models.

A method of scaling is introduced in this paper that allows a machine to be designed based solely on test data rather than a sizing program. This scaling method was verified by utilizing different sets of data to predict the geometry necessary to meet a stage performance curve; the results showed that when various data sets corresponding to different geometries were scaled to the same design point, the predicted geometries converged. The predicted geometry was also compared to the geometry generated by the 1-D wheel sizing program to verify that the method is reliable. This approach to scaling significantly improves the confidence in the predicted performance of new stages.
Fatigue Crack Propagation Analysis of Gear Tooth Under Various Load Conditions and Repaired With Boron/Epoxy Patch
Authors: Ghaffari Mir Ali , Xiao Shaoping
Published: February 2014

In this paper, 3D finite element analyses are conducted to study both crack trajectory and crack growth rate in a gear tooth. Fracture mechanics approach is employed here to model mixed-mode fatigue crack propagation in a gear tooth containing an initial fatigue crack. Two various load conditions are considered: the contact load acting along the whole thickness or the half thickness of gear tooth. Those two load conditions result in different crack trajectories, stress intensity factors and fatigue crack propagation lives of gear tooth. Furthermore, a cracked gear tooth can be repaired by composite patches. It is shown that Boron/Epoxy patches would enhance the fatigue crack propagation life of the gear-tooth.
Study on Numerical Simulation and Performance Test of Tubular Pumping System
Authors: Jin Yan , Liu Chao , Cheng Li
Published: February 2014

Research on three-dimensional flow field in a tubular pumping system using numerical simulation based on the Reynolds time-averaged Navier-Stokes equations and the RNG k–ε turbulent model. By using this method, the performance of pumping system such as head, shaft power and efficiency are predicted based on the calculation of different operating conditions in the discharge range from 20L/s to 35L/s at the same rotating speed. For verifying the accuracy and reliability of the calculation results, a tubular pumping system bedstand is designed for the permarmance test. The comparison of simulation results and the experiment data shown that the calculation performances close agreement with the experiment results in the high efficiency area, but in the condition of large discharge and low discharge, deviations were existed between the two results. Combining with the results of numerical simulation and experiment, which can provide more evidences for the hydraulic performances prediction and optimization design of pumping system.
Structural Modification of a Power Plant’s River Water Intake to Minimize Ice Blockage
Authors: Michell Frank , Politano Marcela , Stallings Jeffrey , Wang Yushi
Published: February 2014

Ice blockage of a power plant’s water intake is of paramount importance since it can lead to an unplanned shutdown of the intake compromising water supply and plant operation. American Electric Power’s (AEP) Conesville Power Plant historically controlled ice accumulation at the river intake by routing to the intake a portion of the warm water return from the condenser on the only operating “once-through” unit’s circulating water system. The unit operating with this once-through cooling system was retired at the end of 2012; thus, the plant lost the use of the condenser outlet/warm water return deicing flow at the river intake.

A numerical study was conducted to evaluate design alternatives to alleviate ice accumulation at the river intake. A numerical model to predict the ice transport and accumulation at the river intake was developed and used to understand the main phenomenon leading to intake blockage.

The effectiveness of mitigation measures was evaluated with the model. A mitigation plan consisting of intake modifications to be implemented during several phases is presented. In the first phase, large pipe openings are cut in the walls separating intake pump wells of previously retired units at the facility. In the second phase, a number of sediment control vanes previously placed in front of the intake are removed to facilitate downstream ice transport. A third phase, if needed to be implemented, involves removing additional sedimentation control vanes and cutting holes in the pump wells on the operating units.

The paper describes the model, discusses numerical results and presents the field experience after implementation of phase one.
Effects of Baffle Overlap Proportion on Shell-Side Performance of Shell and Tube Heat Exchanger With Helical Baffles
Authors: Gao Bin , Bi Qincheng , Nie Zesen
Published: February 2014

Different overlap configurations of discontinuous helical baffles affect the flow pattern of the shell-side fluid directly, and thus there is a significant impact on the flow and heat transfer characteristics of the shell-side fluid. In the present paper, experiments were carried out to study the impact of baffle overlap proportion on the shell-side flow and heat transfer performance of the shell-and-tube heat exchanger with helical baffles (STHEHB). Two different shell-side friction factors, the friction factor per helical pitch (fs,1B) and the friction factor per tube length (fs,1m), were defined based on different reference lengths. The results showed that, since the baffle overlap proportion leads to different helical pitch as well as flow fields in shell side, opposite conclusions are obtained by choosing different reference length. Based on the same Reynolds number, the shell-side Nusselt number of the STHEHB with 10% baffle overlap is higher than that with 50% baffle overlap. The reason is that the larger baffle overlap proportion produces more serious leak flows and weakens the heat transfer in shell side. The comparison of heat transfer coefficient per unit pressure drop versus shell-side flow rate showed that the STHEHB with smaller baffle overlap proportion has better comprehensive heat transfer performance, but the difference between the two decreases gradually with the increase of the flow rate.
Electronic transport properties of top-gated epitaxial-graphene nanoribbon field-effect transistors on SiC wafers
Authors: Hwang Wan Sik , Tahy Kristof , Zhao Pei , Nyakiti Luke O. , Wheeler Virginia D. , Myers-Ward Rachael L. , Eddy Charles R. , Kurt Gaskill D. , (Grace) Xing Huili , Seabaugh Alan , Jena Debdeep
Published: February 2014

Top-gated epitaxial-graphene nanoribbon (GNR) field-effect transistors on SiC wafers were fabricated and characterized at room temperature. The devices exhibited extremely high current densities (∼10 000 mA/mm) due to the combined advantages of the one-dimensionality of GNRs and the SiC substrate. These advantages included good heat dissipation as well as the high optical phonon energy of the GNRs and SiC substrate. An analytical model explains the measured family of ID–VDS curves with a pronounced ‘kink’ at a high electric field. The effective carrier mobility as a function of the channel length was extracted from both the ID–VDS modeling and the maximum transconductance from the ID–VGS curve. The effective mobility decreased for small channel lengths (<1 μm), exhibiting ballistic or quasiballistic transport properties.
Cardiac C‐arm computed tomography using a 3D + time ROI reconstruction method with spatial and temporal regularization
Authors: Mory Cyril , Auvray Vincent , Zhang Bo , Grass Michael , Schäfer Dirk , Chen S. James , Carroll John D. , Rit Simon , Peyrin Françoise , Douek Philippe , Boussel Loïc
Published: February 2014

Purpose:

Reconstruction of the beating heart in 3D + time in the catheter laboratory using only the available C‐arm system would improve diagnosis, guidance, device sizing, and outcome control for intracardiac interventions, e.g., electrophysiology, valvular disease treatment, structural or congenital heart disease. To obtain such a reconstruction, the patientˈs electrocardiogram (ECG) must be recorded during the acquisition and used in the reconstruction. In this paper, the authors present a 4D reconstruction method aiming to reconstruct the heart from a single sweep 10 s acquisition.

Methods:

The authors introduce the 4D RecOnstructiOn using Spatial and TEmporal Regularization (short 4D ROOSTER) method, which reconstructs all cardiac phases at once, as a 3D + time volume. The algorithm alternates between a reconstruction step based on conjugate gradient and four regularization steps: enforcing positivity, averaging along time outside a motion mask that contains the heart and vessels, 3D spatial total variation minimization, and 1D temporal total variation minimization.

Results:

4D ROOSTER recovers the different temporal representations of a moving Shepp and Logan phantom, and outperforms both ECG‐gated simultaneous algebraic reconstruction technique and prior image constrained compressed sensing on a clinical case. It generates 3D + time reconstructions with sharp edges which can be used, for example, to estimate the patientˈs left ventricular ejection fraction.

Conclusions:

4D ROOSTER can be applied for human cardiac C‐arm CT, and potentially in other dynamic tomography areas. It can easily be adapted to other problems as regularization is decoupled from projection and back projection.
An Antifreeze Protein Folds with an Interior Network of More Than 400 Semi-Clathrate Waters
Authors: Sun Tianjun , Lin Feng-Hsu , Campbell Robert L. , Allingham John S. , Davies Peter L.
Published: February 2014

The crystal structure of an antifreeze protein shows a polypentagonal network of water in the protein core.

[Also see Perspective by
Sharp
]
The Coming Copper Peak
Authors: Kerr Richard A.
Published: February 2014

Production of the vital metal will top out and decline within decades, according to a new model that may hold lessons for other resources.
Draft Genome Sequences of Two Cellulolytic
Paenibacillus
sp. Strains, MAEPY1 and MAEPY2, from Malaysian Landfill Leachate
Authors: Chua Patric , Yoo Hye-Seung , Gan Han Ming , Lee Sui-Mae
Published: February 2014

We report the draft genome sequences of two
Paenibacillus
species with cellulose-degrading abilities isolated from landfill leachate. An array of genes putatively involved in cellulose degradation have been identified in both genome sequences, which can benefit various biotechnological industries.
ESwab as an Optional Collection Device for Use with the Affirm VPIII Microbial Test System
Authors: Rivers C. A. , Lee J. Y. , Sharples N. , Ledeboer N. A. , Schwebke J. R.
Published: February 2014

The ESwab collection device was compared to the collection swab provided as part of the Affirm VPIII microbial identification test kit for testing vaginal specimens with the Affirm test system. There was excellent agreement between the two sampling devices for
Candida
spp.,
Gardnerella vaginalis
, and
Trichomonas vaginalis
.
Separate Evolution of Virulent Newcastle Disease Viruses from Mexico and Central America
Authors: Susta Leonardo , Hamal Krishna R. , Miller Patti J. , Cardenas-Garcia Stivalis , Brown Corrie C. , Pedersen Janice C. , Gongora Victor , Afonso Claudio L.
Published: February 2014

An outbreak of Newcastle disease (ND) in poultry was reported in Belize in 2008. The characteristics of three virulent Newcastle disease virus (NDV) isolates from this outbreak (NDV-Belize-3/08, NDV-Belize-4/08, and NDV-Belize-12/08) were assessed by genomic analysis and by clinicopathological characterization in specific-pathogen-free (SPF) chickens. The results showed that all three strains belong to NDV genotype V and are virulent, as assessed by the intracerebral pathogenicity index and the polybasic amino acid sequence at the fusion protein cleavage site. In 4-week-old SPF chickens, NDV-Belize-3/08 behaved as a typical velogenic viscerotropic NDV strain, causing severe necrohemorrhagic lesions in the lymphoid organs, with systemic virus distribution. Phylogenetic analysis of multiple NDV genotype V representatives revealed that genotype V can be divided into three subgenotypes, namely, Va, Vb, and Vc, and that all tested Belizean isolates belong to subgenotype Vb. Furthermore, these isolates are nearly identical to a 2007 isolate from Honduras and appear to have evolved separately from other contemporary viruses circulating in Mexico, clustering into a new clade within NDV subgenotype Vb.
HIV Infection and Microbial Diversity in Saliva
Authors: Li Yihong , Saxena Deepak , Chen Zhou , Liu Gaoxia , Abrams Willam R. , Phelan Joan A. , Norman Robert G. , Fisch Gene S. , Corby Patricia M. , Dewhirst Floyd , Paster Bruce J. , Kokaras Alexis S. , Malamud Daniel
Published: February 2014

Limited information is available about the effects of HIV and subsequent antiretroviral treatment on host-microbe interactions. This study aimed to determine the salivary microbial composition for 10 HIV-seropositive subjects, before and 6 months after highly active antiretroviral therapy (HAART), compared with that for 10 HIV-seronegative subjects. A conventional culture and two culture-independent analyses were used and consistently demonstrated differences in microbial composition among the three sets of samples. HIV-positive subjects had higher levels of total cultivable microbes, including oral streptococci, lactobacilli,
Streptococcus mutans
, and
Candida
, in saliva than did HIV-negative subjects. The total cultivable microbial levels were significantly correlated with CD4
+
T cell counts. Denaturing gradient gel electrophoresis (DGGE), which compared the overall microbial profiles, showed distinct fingerprinting profiles for each group. The human oral microbe identification microarray (HOMIM) assay, which compared the 16S rRNA genes, showed clear separation among the three sample groups.
Veillonella
,
Synergistetes
, and
Streptococcus
were present in all 30 saliva samples. Only minor changes or no changes in the prevalence of
Neisseria
,
Haemophilus
,
Gemella
,
Leptotrichia
,
Solobacterium
,
Parvimonas
, and
Rothia
were observed. Seven genera,
Capnocytophaga
,
Slackia
,
Porphyromonas
,
Kingella
,
Peptostreptococcaceae
,
Lactobacillus
, and
Atopobium
, were detected only in HIV-negative samples. The prevalences of
Fusobacterium
,
Campylobacter
,
Prevotella
,
Capnocytophaga
,
Selenomonas
,
Actinomyces
,
Granulicatella
, and
Atopobium
were increased after HAART. In contrast, the prevalence of
Aggregatibacter
was significantly decreased after HAART. The findings of this study suggest that HIV infection and HAART can have significant effects on salivary microbial colonization and composition.
Characterization of Ocular Methicillin-Resistant Staphylococcus epidermidis Isolates Belonging Predominantly to Clonal Complex 2 Subcluster II
Authors: Bispo Paulo J. M. , Hofling-Lima Ana Luisa , Pignatari Antonio C. C.
Published: February 2014

Staphylococcus epidermidis
is an abundant member of the microbiota of the human skin and wet mucosa, which is commonly associated with sight-threatening infections in eyes with predisposing factors. Ocular
S. epidermidis
has become notorious because of its capability to form biofilms on different ocular devices and due to the evolving rates of antimicrobial resistance. In this study, the molecular epidemiology of 30 ocular methicillin-resistant
S. epidermidis
(MRSE) isolates was assessed using multilocus sequence typing (MLST). Antimicrobial resistance, accessory gene-regulator and staphylococcal cassette chromosome
mec
(SCC
mec
) types, biofilm formation, and the occurrence of biofilm-associated genes were correlated with MLST clonal complexes. Sequence types (STs) frequently found in the hospital setting were rarely found in our collection. Overall, 12 different STs were detected with a predominance of ST59 (30%), ST5 and ST6 (13.3% each). Most of the isolates (93.3%) belonged to the clonal complex 2 (CC2) and grouped mainly within subcluster CC2-II (92.9%). Isolates grouped within this subcluster were frequently biofilm producers (92.3%) with a higher occurrence of the
aap
(84.5%) and
bhp
(46.1%) genes compared to
ica
A (19.2%). SCC
mec
type IV (53.8%) was predominant within CC2-II strains, while 38.4% were nontypeable. In addition, CC2-II strains were frequently multidrug resistant (80.7%) and demonstrated to be particularly resistant to ciprofloxacin (80.8%), ofloxacin (77%), azithromycin (61.5%), and gentamicin (57.7%). Our findings demonstrate the predominance of a particular MRSE cluster causing ocular infections, which was associated with high rates of antimicrobial resistance and particularly the carriage of biofilm-related genes coding for proteinaceous factors implicated in biofilm accumulation.
Distribution of Strain Type and Antimicrobial Susceptibility of Escherichia coli Isolates Causing Meningitis in a Large Urban Setting in Brazil
Authors: Berman Hillary , Barberino Maria Goreth , Moreira Edson Duarte , Riley Lee , Reis Joice N.
Published: February 2014

The clinical management of meningitis caused by
Escherichia coli
is greatly complicated when the organism becomes resistant to broad-spectrum antibiotics. We sought to characterize the antimicrobial susceptibilities, sequence types (ST), and presence of known drug resistance genes of
E. coli
isolates that caused meningitis between 1996 and 2011 in Salvador, Brazil. We then compared these findings to those for
E. coli
isolates from community-acquired urinary tract infections (UTI) that occurred during the same time period and in the same city. We found that 19% of
E. coli
isolates from cases of meningitis and less than 1% of isolates from UTI were resistant to third-generation cephalosporins. The sequence types of
E. coli
isolates from cases of meningitis included ST131, ST69, ST405, and ST62, which were also found among isolates from UTI. Additionally, among the
E. coli
isolates that were resistant to third-generation cephalosporins, we found genes that encode the extended-spectrum beta-lactamases CTX-M-2, CTX-M-14, and CTX-M-15. These observations demonstrate that compared to
E. coli
strains isolated from cases of community-acquired UTI, those isolated from cases of meningitis are more resistant to third-generation cephalosporins, even though the same sequence types are shared between the two forms of extraintestinal infections.
Vancomycin-Variable Enterococcus faecium:
In Vivo
Emergence of Vancomycin Resistance in a Vancomycin-Susceptible Isolate
Authors: Coburn Bryan , Low Donald E. , Patel Samir N. , Poutanen Susan M. , Shahinas Dea , Eshaghi Alireza , Willey Barbara M. , McGeer Allison
Published: February 2014

We report the emergence of vancomycin resistance in a patient colonized with a
vanA
-containing,
vanRS
-negative isolate of
Enterococcus faecium
which was initially vancomycin susceptible. This is a previously undescribed mechanism of drug resistance with diagnostic and therapeutic implications.
Ectromelia Virus Encodes a BTB/kelch Protein, EVM150, That Inhibits NF-κB Signaling
Authors: Wang Qian , Burles Kristin , Couturier Brianne , Randall Crystal M. H. , Shisler Joanna , Barry Michele
Published: February 2014

The NF-κB signaling pathway plays a critical role in inflammation and innate immunity. Consequently, many viruses have evolved strategies to inhibit NF-κB in order to facilitate replication and evasion of the host immune response. Recently, we determined that ectromelia virus, the causative agent of mousepox, contains a family of four BTB/kelch proteins that interact with cullin-3-based ubiquitin ligases. We demonstrate here that expression of EVM150, one of the four BTB/kelch proteins, inhibited NF-κB activation induced by tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β). Although EVM150 inhibited NF-κB p65 nuclear translocation, IκBα degradation was observed, indicating that EVM150 functioned downstream of IκBα degradation. Significantly, expression of the BTB-only domain of EVM150 blocked NF-κB activation, demonstrating that EVM150 functioned independently of the kelch domain and its role as an adapter for cullin-3-based ubiquitin ligases. Furthermore, cullin-3 knockdown by small interfering RNA demonstrated that cullin-3-based ubiquitin ligases are dispensable for TNF-α-induced NF-κB activation. Interestingly, nuclear translocation of IRF3 and STAT1 still occurred in the presence of EVM150, indicating that EVM150 prevented NF-κB nuclear translocation specifically. In addition to identifying EVM150 as an inhibitor of the NF-κB pathway, this study provides new insights into the role of BTB/kelch proteins during virus infection.

IMPORTANCE
With the exception of virulence studies, little work has been done to determine the role of poxviral BTB/kelch proteins during infection. This study, for the first time, has identified a mechanism for the ectromelia virus BTB/kelch protein EVM150. Here, we show that EVM150 is a novel inhibitor of the cellular NF-κB pathway, an important component of the antiviral response. This study adds EVM150 to the growing list of NF-κB inhibitors in poxviruses and provides new insights into the role of BTB/kelch proteins during virus infection.
Naturally Occurring Mutations in the PA Gene Are Key Contributors to Increased Virulence of Pandemic H1N1/09 Influenza Virus in Mice
Authors: Sun Yipeng , Xu Qi , Shen Ye , Liu Linqing , Wei Kai , Sun Honglei , Pu Juan , Chang Kin-Chow , Liu Jinhua
Published: February 2014

We examined the molecular basis of virulence of pandemic H1N1/09 influenza viruses by reverse genetics based on two H1N1/09 virus isolates (A/California/04/2009 [CA04] and A/swine/Shandong/731/2009 [SD731]) with contrasting pathogenicities in mice. We found that four amino acid mutations (P224S in the PA protein [PA-P224S], PB2-T588I, NA-V106I, and NS1-I123V) contributed to the lethal phenotype of SD731. In particular, the PA-P224S mutation when combined with PA-A70V in CA04 drastically reduced the virus's 50% mouse lethal dose (LD
50
), by almost 1,000-fold.
Identification of Novel, Highly Expressed Retroviral MicroRNAs in Cells Infected by Bovine Foamy Virus
Authors: Whisnant Adam W. , Kehl Timo , Bao Qiuying , Materniak Magdalena , Kuzmak Jacek , Löchelt Martin , Cullen Bryan R.
Published: February 2014

While numerous viral microRNAs (miRNAs) expressed by DNA viruses, especially herpesvirus family members, have been reported, there have been very few reports of miRNAs derived from RNA viruses. Here we describe three miRNAs expressed by bovine foamy virus (BFV), a member of the spumavirus subfamily of retroviruses, in both BFV-infected cultured cells and BFV-infected cattle. All three viral miRNAs are initially expressed in the form of an ∼122-nucleotide (nt) pri-miRNA, encoded within the BFV long terminal repeat U3 region, that is subsequently cleaved to generate two pre-miRNAs that are then processed to yield three distinct, biologically active miRNAs. The BFV pri-miRNA is transcribed by RNA polymerase III, and the three resultant mature miRNAs were found to contribute a remarkable ∼70% of all miRNAs expressed in BFV-infected cells. These data document the second example of a retrovirus that is able to express viral miRNAs by using embedded proviral RNA polymerase III promoters.

IMPORTANCE
Foamy viruses are a ubiquitous family of nonpathogenic retroviruses that have potential as gene therapy vectors in humans. Here we demonstrate that bovine foamy virus (BFV) expresses high levels of three viral microRNAs (miRNAs) in BFV-infected cells in culture and also in infected cattle. The BFV miRNAs are unusual in that they are initially transcribed by RNA polymerase III as a single, ∼122-nt pri-miRNA that is subsequently processed to release three fully functional miRNAs. The observation that BFV, a foamy virus, is able to express viral miRNAs in infected cells adds to emerging evidence that miRNA expression is a common, albeit clearly not universal, property of retroviruses and suggests that these miRNAs may exert a significant effect on viral replication
in vivo
.
Examination of Surface Conditions and Other Physical Properties of Commonly Used Stainless Steel Acupuncture Needles
Authors: Xie Yi Min , Xu Shanqing , Zhang Claire Shuiqing , Xue Charlie Changli
Published: February 2014

Objectives

The present work examined the surface conditions and various other physical properties of sterilised single-use stainless steel acupuncture needles from two of the most popular brands widely used in many countries.

Methods

Scanning electron microscope (SEM) images were taken for 10 randomly chosen needles from each brand. Further SEM images were taken after each of these needles underwent a standard manipulation with an acupuncture needling practice gel. A comparison of forces and torques during the needling process was also carried out.

Results

The SEM images revealed significant surface irregularities and inconsistencies at the needle tips, especially for needles from one of the two brands. Metallic lumps and small, loosely attached pieces of material were observed on the surfaces of some needles. Some of the lumps and pieces of material seen on the needle surfaces disappeared after the acupuncture manipulation. If these needles had been used on patients, the metallic lumps and small pieces of material could have been deposited in human tissues, which could have caused adverse events such as dermatitis. Malformed needle tips might also cause other adverse effects including bleeding, haematoma/bruising, or strong pain during needling. An off-centre needle tip could result in the needle altering its direction during insertion and consequently failing to reach the intended acupuncture point or damaging adjacent tissues.

Conclusions

These findings highlight the need for improved quality control of acupuncture needles, with a view to further enhancing the safety and comfort of acupuncture users.
Isolated abdominal aortic dissection
Authors: Tang Ee Ling Serene , Chong Choon Seng , Narayanan Sriram
Published: February 2014

Isolated acute abdominal aortic dissection is a rare condition, accounting for 1.3% of all aortic dissections.1 It may be classified as iatrogenic, traumatic or spontaneous.2 To date, only 92 patients have been reported in western literature. All the reports were based on the Caucasian population, and the mean age according to the International Registry of Acute abdominal aortic dissection (IRAD) was 67.7 ± 13.3 years.1 We report a case of an isolated infrarenal abdominal aortic dissection in a middle age Asian man, and our subsequent management.
Factors associated with the clinical outcomes of paediatric out-of-hospital cardiac arrest in Japan
Authors: Nagata Takashi , Abe Takeru , Noda Eiichiro , Hasegawa Manabu , Hashizume Makoto , Hagihara Akihito
Published: February 2014

Objectives

To better understand and predict clinical outcomes of paediatric out-of-hospital cardiac arrest (OHCA).

Design

A population-based, observational study.

Setting

The National Japan Utstein Registry.

Participants

2900 children aged 5–17 years who experienced OHCA and received resuscitation by emergency responders. Signal detection analysis using 17 variables was applied to identify factors associated with OHCA outcomes; the primary endpoint was cerebral performance category (CPC) 1 or 2. A validation study was conducted to verify the model.

Results

OHCA was identified as cardiac origin in 706 participants and non-cardiac origin in 2194 participants. Rates of CPC 1 or 2 for cardiac and non-cardiac causes were 20% and 6.4%, respectively. Cardiac origin arrest was categorised following signal detection into six subgroups defined by public automated external defibrillator use, defibrillation by emergency medical service, age, initial ECG rhythm and eye-witness to arrest; the ranges of CPC 1 or 2 in the six subgroups were between 87.5% and 0.7%. Non-cardiac origin arrest was categorised into four subgroups. Bystander rescue breathing was the most significant factor contributing to outcome; additionally, two other factors—eye-witness to arrest and age—were also significant. CPC 1 or 2 rates ranged between 38.5% and 4% across the four subgroups. Rates of CPC 1 or 2 in the validation study did not differ among any subgroup.

Conclusions

For children who have OHCA from non-cardiac origin, bystander rescue breathing is mandatory to achieve CPC 1 or 2.
A comparison of the causes of blindness certifications in England and Wales in working age adults (16–64 years), 1999–2000 with 2009–2010
Authors: Liew Gerald , Michaelides Michel , Bunce Catey
Published: February 2014

Objectives

To report on the causes of blindness certifications in England and Wales in working age adults (16–64 years) in 2009–2010; and to compare these with figures from 1999 to 2000.

Design

Analysis of the national database of blindness certificates of vision impairment (CVIs) received by the Certifications Office.

Setting and participants

Working age (16–64 years) population of England and Wales.

Main outcome measures

Number and cause of blindness certifications.

Results

The Certifications Office received 1756 CVIs for blindness from persons aged between 16 and 64 inclusive between 1 April 2009 and 31 March 2010. The main causes of blindness certifications were hereditary retinal disorders (354 certifications comprising 20.2% of the total), diabetic retinopathy/maculopathy (253 persons, 14.4%) and optic atrophy (248 persons, 14.1%). Together, these three leading causes accounted for almost 50% of all blindness certifications. Between 1 April 1999 and 31 March 2000, the leading causes of blindness certification were diabetic retinopathy/maculopathy (17.7%), hereditary retinal disorders (15.8%) and optic atrophy (10.1%).

Conclusions

For the first time in at least five decades, diabetic retinopathy/maculopathy is no longer the leading cause of certifiable blindness among working age adults in England and Wales, having been overtaken by inherited retinal disorders. This change may be related to factors including the introduction of nationwide diabetic retinopathy screening programmes in England and Wales and improved glycaemic control. Inherited retinal disease, now representing the commonest cause of certification in the working age population, has clinical and research implications, including with respect to the provision of care/resources in the NHS and the allocation of research funding.
Behavioural sleep problems in children with attention-deficit/hyperactivity disorder (ADHD): protocol for a prospective cohort study
Authors: Lycett Kate , Sciberras E , Mensah F K , Gulenc A , Hiscock H
Published: February 2014

Introduction

Children with attention-deficit/hyperactivity disorder (ADHD) commonly experience behavioural sleep problems, yet these difficulties are not routinely assessed and managed in this group. Presenting with similar symptoms to ADHD itself, sleep problems are complex in children with ADHD and their aetiology is likely to be multifactorial. Common internalising and externalising comorbidities have been associated with sleep problems in children with ADHD; however, this relationship is yet to be fully elucidated. Furthermore, limited longitudinal data exist on sleep problems in children with ADHD, thus their persistence and impact remain unknown. In a diverse sample of children with ADHD, this study aims to: (1) quantify the relationship between sleep problems and internalising and externalising comorbidities; (2) examine sleep problem trajectories and risk factors; and (3) examine the longitudinal associations between sleep problems and child and family functioning over a 12-month period.

Methods and analysis

A prospective cohort study of 400 children with ADHD (150 with no/mild sleep problems, 250 with moderate/severe sleep problems) recruited from paediatric practices across Victoria, Australia. The children's parents and teacher provide data at baseline and 6-month and 12-month post enrolment.

Key measures

Parent report of child's sleep problem severity (no, mild, moderate, severe); specific sleep domain scores assessed using the Child Sleep Habits Questionnaire; internalising and externalising comorbidities assessed by the Anxiety Disorders Interview Schedule for Children IV/Parent version.

Analyses

Multiple variable logistic and linear regression models examining the associations between key measures, adjusted for confounders identified a priori.

Ethics and dissemination

Ethics approval has been granted. Findings will contribute to our understanding of behavioural sleep problems in children with ADHD. Clinically, they could improve the assessment and management of sleep problems in this group. We will seek to publish in leading paediatric journals, present at conferences and inform Australian paediatricians through theAustralian Paediatric Research Network.