bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Beamforming Enhancement of Locomotive Cabin Speech
Authors: Muecke Karl , Southward Steve C.
Published: June 2009

The noisy and monotonous environment of a locomotive cabin is certainly not conducive to clear communication or to high levels of crew alertness. Both of these problems have a negative impact on the operational safety of the locomotive. In this paper, an acoustic beamforming system is developed and evaluated for enhancing the speech signals measured in a locomotive cabin. Higher signal-to-noise ratio (SNR) speech signals can significantly improve communication as well as enable the use of speech-based alertness detection methods. Acoustic beamforming utilizes a spatially distributed array of low-cost microphones permanently mounted in the locomotive cabin trim, with a digital signal processing algorithm to effectively create a focused directional microphone which can be pointed at any crew member in the cabin. Preliminary experimental testing of this system in a green truck cabin has been successful, even with very high levels of noise.
Wheel/Rail Dynamics Simulation for Optimising Minimum Grade Lengths to High-Speed Railways
Authors: Liu Zengjie , Wang Lan
Published: June 2009

Based on the principle of no car vibrations interference when trains pass grade section from the end of front vertical curve to the start of latter vertical curve, using railway wheel/rail simulation NUCARS™ software, some dynamics simulation studies for minimum grade lengths on high speed railway lines were made. The dynamics simulation results show that, the minimum tangent lengths between vertical transition curves should be more than 0.43V in meters (V is speed of train, km/h). So the minimum length is 800 meters when the vertical curve radius is 25000 meters, and 900 meters when radius is 30000 meters for the Chinese Dedicated Passenger Railway lines (PDLs) on which maximum speed is 350 km/h and ruling gradient is 12‰.
Nano-Interfacial Chemistry of Waste Paper Deinking Processes Using Fatty Ethoxylates
Authors: Yehia Ahmed , El-Midani Ayman A. , Ibrahim Suzan S. , Miller Jan D.
Published: June 2009

The forces affecting the ink particles attachment to the paper substrates control the inking and deinking processes. In deinking process, the detachment of ink particles represents a big challenge due to the presence of nano-sized ink particles which can not be separated by conventional means, therefore, it needs special type of treatment to adapt the chemistry of the surrounding solution to control the interfacial forces to separate the ink particle and make their detachment easier. Although studies have been made to correlate chemical structure of fatty alcohol ethoxylates with the efficiency of ink removal, there is still a significant lack of fundamental knowledge regarding the influence of the ethoxylate alcohol on the interaction forces between particulates involved in the deinking process. In this research, fundamental study of the effect of nano-sized ethoxylated alcohol molecules, which exhibits high potential for application in wastepaper deinking, on the ink particle detachment due to changes in the interfacial forces will be studied. In addition, the ability of ethoxylated alcohol to produce nano-size bubbles will be tested in terms of their effect on the ink particle removal. Furthermore, relationship between molecular structure of ethoxylated fatty alcohols (length and ratio of hydrophobic and hydrophilic parts) and ink (toner) will be characterized using atomic force microscopy (AFM) colloidal probe technique.
Nanocomposites With Strong Optical Resonances: Silver Nanoparticles-Organic Molecules Systems
Authors: Smejkal Petr , Vlckova Blanka , Pavel Ioana , Moskovits Martin , Sladkova Magdalena , Siskova Karolina , Slouf Miroslav
Published: June 2009

The ability of selected molecular species to link Ag nanoparticles into dimers and/or small aggregates has been tested. Dimercaptocarborane and ethidium bromide have been shown to link Ag nanoparticles via their bonding to Ag nanoparticle surface probably by the two strongly argentophilic groups in para-positions. Alternatively, dimers and small aggregates were assembled through an electrostatic interaction between negatively charged citrate-modified and positively charged polylysine-modified Ag nanoparticles, and a subsequent incorporation of 5, 10, 15, 20-tetrakis(4-sulphonato-phenyl)porphine (TSPP) into such preprepared nanoobjects has been probed by SERRS (surface-enhanced resonance Raman scattering). Formation of dimers and small aggregates has been established by TEM (transmission electron microscopy) and SEM (scanning electron microscopy). SE(R)RS spectral measurements from specific locations of samples containing molecularly-linked dimers and aggregates have shown temporal fluctuations (blinking) of the SE(R)RS signal, which indicates, that the signal likely originates from molecules located in the strong, nanoscale localized optical fields dubbed hot spots. In addition to that, characteristic bands of graphitic carbon were observed in the spectra and their intensities (together with the spectral background intensities) strongly varied with time and from one spectrum to another. One of the possible explanations of these observations is a photochemical and/or thermal decomposition of the molecules located in hot spots combined with diffusion of unperturbed molecules into hot spots.
Nanostructured Ti-Fe Thin Layered Photocatalyst via Sol-Gel Technique
Authors: Aboul-Gheit Ahmed K. , Mahmoud Sawsan A. , Moustafa Yasser M.
Published: June 2009

The finding of of Zhu et al. [1] that iron-ion-doped TiO2 powders by hydrothermal hydrolysis and crystallization exhibited that the amount of doped iron ion significantly affected the phoyocatalytic degradation activity of XRG yellow dye and Fe optimum content could enhance photocatalytic activity under UV and visible light irradiation has encourage us to carry out this work. Hence, we prepared and examined the photocatalytic activities of a series of TiO2/Fe2O3 mixtures of thin layers of TiO2 and Fe2O3 using the sol-gel method and found that the TiO2(5)/Fe2O3(1) catalyst the most active for anthracene photodegradation. This catalyst acquired the highest surface area, proper pore size distribution and the smaller nano-particle size.
Texture During ECAP and Post ECAP Simple Compression of Commercial Purity 1050 Aluminum Alloy
Authors: El-Danaf Ehab A.
Published: June 2009

Electron back scattered diffraction (EBSD) was used to document the texture developed during ECAP. Samples of commercial purity aluminum processed to 8 passes through route BC and route C were examined on two planes (flow plane and the plane normal to the extrusion direction) and pole figures and orientation distribution function plots (ODFs) were generated. The results of the texture evolved in the as ECAPed samples gave some interpretation for the different mechanical properties realized via the two routes, though the amount of imposed equivalent accumulated strain was the same. Furthermore, the texture developed when ECAPed samples were subsequently compressed was also documented, and the examination of pole figures, ascertained that there is a transition of texture accompanied with the strain path change from simple shear to simple compression.
Powder Injection Molding of Cu-Based Amorphous Powders and Fe-Based Metamorphic Powders
Authors: Son Chang-Young , Kim Chang Kyu , Ha Dae Jin , Yoon Tae Shik , Lee Sunghak , Kim Nack J.
Published: June 2009

Powder injection molding (PIM) process was applied to Cu-based amorphous alloy powders and Fe-based metamorphic alloy powders, and microstructure, hardness, and wear resistance of the PIM products were analyzed. When Cu-based amorphous powders were injection-molded and sintered at 470 °C, sintering was not made since most of amorphous phases were replaced by crystalline phases. When sintered at higher temperatures, volume fraction of pores inside the sintered specimens decreased, but sintering was not properly conducted. When Fe-based metamorphic powders were injection-molded and then sintered at 1200 °C, completely densified products with almost no pores were obtained. They contained 34 vol.% of (Cr, Fe)2B borides dispersed in the austenitic matrix without amorphous phases. Since these (Cr, Fe)2B borides were hard and thermally stable, hardness, high-temperature hardness, and wear resistance of the PIM products of Fe-based metamorphic powders were twice as high as those of conventional PIM stainless steel products. These findings suggested new applicability of the PIM products of Fe-based metamorphic powders to structures and parts requiring excellent mechanical properties.
Evaluation of Hybrid Chitosan-Cellulose Biodegradable Scaffolds for Tissue Engineering Applications
Authors: Waly Gihan H. , Abdel Hamid Inas S. , Sharaf Mohamed A. , Marei Mona K. , Mostafa Naglaa A.
Published: June 2009

Natural polymers continue to provide effective biocompatible scaffolds for use in tissue engineering applications. In some respects, their chemical structure closely mimics that of the extracelluar matrix of biological tissues. Eventhough a wide variety of biopolymers can be used for these applications, no single polymer has been yet found to fulfill all requirements needed in a scaffold material. In an attempt to combine the advantages of two natural polymers, hybrid scaffolds of chitosan/cellulose constructs had been evaluated as candidates for tissue engineering applications. Four groups of hybrid chitosan/cellulose scaffolds were prepared with different cellulose concentrations. The surface and bulk porosities scaffolds have been examined using scanning electron microscope (SEM). The SEM photographs revealed that all hybrid scaffold groups exhibited an interconnected highly porous structure. Percent porosity and pore volume distribution were evaluated using mercury intrusion porosimetry (MIP). The scaffolds were mechanically tested to evaluate their compressive strength. The biodegradation rate in lysozyme-containing saline had been also determined over a six week period. The MIP results showed that all scaffolds had percent porosity in excess of 75% and that the percent porosity decreased by increasing the cellulose concentration. The incremental intrusion versus diameter curves revealed that most of the scaffolds porosity occurred in the macro-scale. The compressive strength of the scaffold showed an increase with an increase in the cellulose concentration. However, the biodegradation rate was found to vary inversely with the cellulose content in the hybrid. In order to evaluate the cytocompatibility of the chitosan-based scaffolds, mesenchymal stem cells were statically seeded and their attachment had been evaluated. The results revealed that after three and eight day of seeding, the scaffolds became highly populated with cells. This serves as a clear indicatation that the scaffolds thus investigated promote cell attachment and support cell proliferation and proliferation. Thus, the investigated scaffolds are promising candidates for tissue engineering applications.
Oxidation Kinetics of Nano Crystalline Tin Oxide Conductive Thin Films
Authors: Guler Mehmet Oguz , Alaf Mirac , Gultekin Deniz , Akbulut Hatem , Alp Ahmet
Published: June 2009

Tin oxide was the first transparent conductor to have achieved significant commercialization. SnO2 is an n-type semiconductor with an optical band gap of about 3.6 eV in poly crystalline form. One of the main reasons for the wide use is its rather desirable characteristic of having both, high optical transmittance and high electrical conductivity. Under optimum deposition conditions, tin oxide crystallizes in the tetragonal (rutile) structure. In this study, nano crystalline thin oxide conductive thin films has been manufactured by thermal evaporation techniques onto steel substrates using metallic tin targets and oxidation kinetics have been studied after D.C. plasma oxidation by using XRD (X-Ray Diffraction). The activation energy of SnO and SnO2 from Sn phase transformations has also been studied.
Improving the Public Acceptance of WTE: Session 8
Authors: Napoli Peter A. , Sampson Lindsey , Davidov Robin , Kamuk Bettina
Published: June 2009

This topic is important because of the growing need for us to produce and supply low cost energy for public consumption. Demand has increased exponentially, and in order to reduce dependence on foreign oil, coal, and natural gas we need to utilize waste to its full potential. Three major waste to energy plant expansions are happening now at Olmstead WTE, Minnesota and at Lee and Hillsborough Counties, in Florida. New “Greenfield” construction is planned at Harford, Carroll, and Fredrick Counties, in Maryland.
Odor Monitoring and Mitigation at the Hennepin County Waste to Energy Facility
Authors: Smith Jake
Published: June 2009

Hennepin Energy Recovery Center (HERC) is a waste to energy facility owned by Hennepin County and operated by Covanta Energy. HERC has been in operation since 1989. The facility burns 365,000 tons of residential and commercial solid waste per year and generates about 34 mega-watts of electricity that is sold to Xcel Energy. HERC is located on the north side of downtown Minneapolis in the Historic Warehouse District, a neighborhood that is changing from industrial to a more commercial/residential mix with loft conversions and construction of new condominiums. The Minnesota Twins baseball team is also siting a new stadium in the parking lot immediately southeast of the facility. The potential for odors from the tipping floor of the facility affecting the neighborhood has become more of a concern due to the changes in the neighborhood. In March 2004 the County began an odor study. This included developing baseline information on odors from HERC and from the surrounding community by conducting daily odor monitoring at select points on the facility property and throughout the community: • Determining how far odors from HERC migrate into the community. • Quantifying detected odors using a Nasal Ranger. • Determining the factors that contribute to these odors. • Developing a method of controlling these odors. • Continued monitoring to determine the impact of mitigation methods. Odors detected were characterized as garbage odors, garbage-related odors, and neighborhood odors. Baseline data showed that while garbage odors from HERC were mostly undetectable beyond the perimeter of the property, there was room for improvement in decreasing the presence and intensity of these odors. The tipping hall was designed to operate under negative pressure to control odors, however the entrance and exit doors were always open and a negative pressure could not be maintained.
The Ebara Advanced Fluidization Process for Energy Recovery and Ash Vitrification
Authors: Suzuki Shunzi
Published: June 2009

The Ebara Corporation has developed several types of fluidized bed reactors for the processing of various types of solid wastes. The Ebara Advanced Fluidization Process for energy recovery and ash vitrification has been applied in the fifteen plants (29 lines) listed in Table 1. Most of them process municipal solid wastes (MSW) and plant capacities range from 100 (Sakata) to 300 (Tokyo) tones per day. The total treatment capacity is about 2,700 tones per day and the thermal capacity 387 M W.
Development and Testing of a High Thermal Conductivity Refractory Tile System in a Waste-to-Energy Combustion Unit
Authors: Stephan Patrick M.
Published: June 2009

Refractory systems are used for tube wall protection in waste-to-energy (WTE) boilers. Through the years, continuous adjustments have been made to the refractory materials and product designs. Design modifications have incrementally improved tile systems from bolt-on to hidden-clip to back-cast systems. Different refractory types, such as gunning cements and other monolithics, have also been used with varying degrees of success. A new refractory system is currently evolving, borrowed from other advanced high temperature applications and adapted to fit WTE boiler designs. This new system is a radical change in design from conventional refractory systems.
Waste-to-Energy in Europe and Technology Highlights From Von Roll Inova Projects
Authors: Brunner Martin , Sigg Alfred
Published: June 2009

Von Roll Inova is a major provider of thermal treatment technologies ranging from combustion, energy recovery, air pollution control, and residue processing. The company is headquartered in Switzerland and its portfolio includes over 300 WTEs around the world, processing more than 100,000 metric tons of solid wastes per day. This paper discusses the technological and political trends in Europe regarding waste-to-energy, the state-of-the-art-technology and presents an an overview of recently executed projects by Von Roll Inova. During the hiatus on new plant construction in the U.S., European countries pursued a variety of different approaches. Not all the results showed environmental, social or economic promise. Of the aspects developed since the mid-nineties, some are applicable to the United States. Particularly the advances in air pollution control technology and improved thermal efficiency will be useful as new Waste-to-Energy capacity is added in the U.S. and delays in permitting may be avoided by taking advantage of such experience transfers.
Grate and Boiler Technology Assessment for a New WTE Plant in the U.S.
Authors: Gesell Gregory , Clark Matthew
Published: June 2009

The Olmsted County Waste-to-Energy Facility (WTE) is in the process of expanding the facility capacity. The original facility began commercial operation in 1987 and consists of two 100 tpd units, equipped with Riley boilers and Takuma grates. The plant was built during the construction boom for WTE plants in the U.S. At that time there were some industry leading technologies, and also were many other players in the field offering European, Japanese, as well as U.S. technologies for the combustion of MSW. The industry has changed since those exciting times when nearly every city and urban county in the country would at least consider WTE. Years of industry stagnation caused by a number of events and trends resulted in the merger, bankruptcy, or pull out of WTE engineering firms in the U.S. market. Today there are only a handful of technologies used and an even smaller fraternity of private operating companies. Many private and publicly operated WTE facilities continue to operate successfully and recently several are in various stages of facility expansion or new plant development. Olmsted County started this process three years ago laying the groundwork for a facility expansion to double its capacity. Currently, the County is in the engineering phase of the expansion and expects to begin construction in 2007. The engineering effort includes consideration of commercially available combustion technologies and procurement of this equipment. This paper looks briefly at the historical availability of grate and boiler technologies and the findings of the County’s assessment of technologies available in the U.S. market.
Next Generation of Waste Fired Power Plants: Getting the Most Out of Your Trash!
Authors: Madsen Ole Hedegaard
Published: June 2009

It is generally believed that incineration systems based on combustion grates are old fashioned and it is widely understood that there are no new developments in that area. This image is incorrect; it is proven technology – but it is still improving! The waste-to-energy sector has undergone a rapid technological development over the latest 10 years. Lately, new technologies have been introduced, such as Advanced Combustion Control (ACC), the use of Inconel® protection in boilers, boiler cleaning, water cooled combustion grates and wear zones. Moreover, the presentation will show how modern engineering tools such as CFD (Computational Fluid Dynamics software) are used for designing the best furnace and boiler configurations. These new developments are illustrated through a case study of a new class of waste fired power plant burning 20 tonnes of waste per hour. This paper will present some of the test results from operating the plant, including the development of a new advanced control system.
New Development in EfW Boiler Process Modeling: Fully Integrated CFD Model
Authors: Epelbaum Greg , Zhang Hanwei
Published: June 2009

This paper focuses on a Computational Fluid Dynamics (CFD) application to Energy-from-Waste (EfW) boiler systems, which are much smaller than utility boilers, but typically have more complicated design and performance issues due to the nature of their fuel: municipal solid waste (MSW). The majority of the commercially available CFD software packages have impressive capabilities in homogeneous flow modeling, which make them very suitable for gas fired boilers and with some reasonable simplifications to oil and pulverized coal fired boilers. But this is not the case for EfW boilers, especially mass-burn technology, where MSW combustion on the grate is the “heart” of the process. These boilers have two interacting phases: MSW burning on the grate and combustion products with entrained fly ash particles above the grate. This challenge has been recognized from the very first applications of CFD modeling in the EfW industry. This paper describes several approaches to numeric modeling of MSW boilers. In the most successful cases, two different models have been built: one for the grate combustion and another for the homogeneous gas flow, with back-and-forth iterations between these two models. Such an approach has given Covanta Energy (Covanta) a good start in its CFD modeling program. A number of models have been built, tested and validated, resulting in several successful project executions. However, some serious limitations have been found in this approach as explained in this paper. Recognizing these deficiencies, Covanta has recently made a new significant step in its CFD development program by creating an innovative, fully integrated CFD model that comprises solid fuel combustion on the grate, gaseous phase interactions above the grate, and the rest of the boiler. While this integrated model and its validation are still in progress, Covanta is moving forward on its application to on-going projects.
The Lee County WTE Expansion Project: Building a New WTE Unit in the 21st Century
Authors: Castro Donald J. , Sampson Lindsey J.
Published: June 2009

The Lee County Expansion Project is a 636 ton per day Municipal Waste Combustor (MWC) in late stages of construction/startup, located in Ft. Myers, FL. The new unit complements the existing 1200 ton per day two-unit facility owned by the County and operated by Covanta Lee, Inc., which has been in service since 1994. The new unit is the first MWC permitted and constructed under the EPA’s New Source Performance Standards (NSPS) since they were promulgated in the 1990’s. This paper will describe the basic contractual arrangements, permitting, design and construction features, and overall costs for the expansion project.
Improving Plant Operations: Retrofit of Waste-to-Energy Stoker Controls to Improve Combustion and Availability
Authors: Polidore John
Published: June 2009

This paper discusses the retrofit of the stoker grate hydraulic system and controls at Montenay’s Montgomery County Pennsylvania Waste-to Energy Facility. Since commencing operations in 1991, the stoker grate system was plagued with operational disruptions caused by fusion of its moving grates. The existing hydraulic system was designed to control the movement of waste on the grate sections by maintaining constant velocity stoker grate movement and varying the length of time the grates were dormant between cycles of grate movement. The purpose of the retrofit was to improve grate operations by replacing the existing hydraulic system with a system capable of providing continuous stoker movement at variable velocities, eliminating the dormant cycle of the grate movement.
Experiences With On-Line Explosive De-Slagging at Covanta WTE Facilities
Authors: Vorfeld Jeff
Published: June 2009

An on-line cleaning technique perfected in Europe, which places low-yield explosive charges in close proximity to tube lane pluggage, and uses pre- and post-cleaning video camera surveillance to document results, has been tested at three WTE facilities in the western U.S. operated by Covanta. Testing indicates several tangible benefits relative to the more traditional off-line blasting, water washing (on-line and off-line), and stick blasting (on-line), including: • substantial elimination of cleaning related downtime between maintenance outages; • longer runtimes with less overall fouling and pluggage related ailments; • reduced off-line cleaning time at the beginning of major outages to the benefit of the outage schedule; • exemplary safety of the on-line cleaning process; • less wear and tear on pressure parts and boiler casings; and, • almost no fugitive dust problems in the boiler house that may occur with off-line blasting. The process starts with an initial video survey of fouling conditions. A water-cooled camera with purge air and temperature monitoring is inserted into the flue gas to record the fouling condition of the boiler. Following the survey, a cleaning plan is developed. Shots consist of low-yield detonating cord encased in thin gage aluminum alloy tubing. The charges are positioned in the gas lanes between tubes while being cooled with a water-air mixture and detonated. Following the cleaning effort, a final camera survey is done to verify the cleaning effectiveness, and to follow up with touch-up cleaning if necessary.
Inactivation of
Escherichia coli
Endotoxin by Soft Hydrothermal Processing
Authors: Miyamoto Toru , Okano Shinya , Kasai Noriyuki
Published: June 2009

Bacterial endotoxins, also known as lipopolysaccharides, are a fever-producing by-product of gram-negative bacteria commonly known as pyrogens. It is essential to remove endotoxins from parenteral preparations since they have multiple injurious biological activities. Because of their strong heat resistance (e.g., requiring dry-heat sterilization at 250°C for 30 min) and the formation of various supramolecular aggregates, depyrogenation is more difficult than sterilization. We report here that soft hydrothermal processing, which has many advantages in safety and cost efficiency, is sufficient to assure complete depyrogenation by the inactivation of endotoxins. The endotoxin concentration in a sample was measured by using a chromogenic limulus method with an endotoxin-specific limulus reagent. The endotoxin concentration was calculated from a standard curve obtained using a serial dilution of a standard solution. We show that endotoxins were completely inactivated by soft hydrothermal processing at 130°C for 60 min or at 140°C for 30 min in the presence of a high steam saturation ratio or with a flow system. Moreover, it is easy to remove endotoxins from water by soft hydrothermal processing similarly at 130°C for 60 min or at 140°C for 30 min, without any requirement for ultrafiltration, nonselective adsorption with a hydrophobic adsorbent, or an anion exchanger. These findings indicate that soft hydrothermal processing, applied in the presence of a high steam saturation ratio or with a flow system, can inactivate endotoxins and may be useful for the depyrogenation of parenterals, including end products and medical devices that cannot be exposed to the high temperatures of dry heat treatments.
Genome-Derived Criteria for Assigning Environmental
narG
and
nosZ
Sequences to Operational Taxonomic Units of Nitrate Reducers
Authors: Palmer Katharina , Drake Harold L. , Horn Marcus A.
Published: June 2009

Ninety percent of cultured bacterial nitrate reducers with a 16S rRNA gene similarity of ≥97% had a
narG
or
nosZ
similarity of ≥67% or ≥80%, respectively, suggesting that 67% and 80% could be used as standardized, conservative threshold similarity values for
narG
and
nosZ
, respectively (i.e., any two sequences that are less similar than the threshold similarity value have a very high probability of belonging to different species), for estimating species-level operational taxonomic units. Genus-level tree topologies of
narG
and
nosZ
were generally similar to those of the corresponding 16S rRNA genes. Although some genomes contained multiple copies of
narG
, recent horizontal gene transfer of
narG
was not apparent.
Linking Microbial Community Function to Phylogeny of Sulfate-Reducing
Deltaproteobacteria
in Marine Sediments by Combining Stable Isotope Probing with Magnetic-Bead Capture Hybridization of 16S rRNA
Authors: Miyatake Tetsuro , MacGregor Barbara J. , Boschker Henricus T. S.
Published: June 2009

We further developed the stable isotope probing, magnetic-bead capture method to make it applicable for linking microbial community function to phylogeny at the class and family levels. The main improvements were a substantial decrease in the protocol blank and an approximately 10-fold increase in the detection limit by using a micro-elemental analyzer coupled to isotope ratio mass spectrometry to determine
13
C labeling of isolated 16S rRNA. We demonstrated the method by studying substrate utilization by
Desulfobacteraceae
, a dominant group of complete oxidizing sulfate-reducing
Deltaproteobacteria
in marine sediments. Stable-isotope-labeled [
13
C]glucose, [
13
C]propionate, or [
13
C]acetate was fed into an anoxic intertidal sediment. We applied a nested set of three biotin-labeled oligonucleotide probes to capture
Bacteria
,
Deltaproteobacteria
, and finally
Desulfobacteraceae
rRNA by using hydrophobic streptavidin-coated paramagnetic beads. The target specificities of the probes were examined with pure cultures of target and nontarget species and by determining the phylogenetic composition of the captured sediment rRNA. The specificity of the final protocol was generally very good, as more than 90% of the captured 16S rRNA belonged to the target range of the probes. Our results indicated that
Desulfobacteraceae
were important consumers of propionate but not of glucose. However, the results for acetate utilization were less conclusive due to lower and more variable labeling levels in captured rRNA. The main advantage of the method in this study over other nucleic acid-based stable isotope probing methods is that
13
C labeling can be much lower, to the extent that δ
13
C ratios can be studied even at their natural abundances.
Cytopathological Effects of
Bacillus sphaericus
Cry48Aa/Cry49Aa Toxin on Binary Toxin-Susceptible and -Resistant
Culex quinquefasciatus
Larvae
Authors: de Melo Janaina Viana , Jones Gareth Wyn , Berry Colin , Vasconcelos Romero Henrique Teixeira , de Oliveira Cláudia Maria Fontes , Furtado André Freire , Peixoto Christina Alves , Silva-Filha Maria Helena Neves Lobo
Published: June 2009

The Cry48Aa/Cry49Aa mosquitocidal two-component toxin was recently characterized from
Bacillus sphaericus
strain IAB59 and is uniquely composed of a three-domain Cry protein toxin (Cry48Aa) and a binary (Bin) toxin-like protein (Cry49Aa). Its mode of action has not been elucidated, but a remarkable feature of this protein is the high toxicity against species from the
Culex
complex, besides its capacity to overcome
Culex
resistance to the Bin toxin, the major insecticidal factor in
B. sphaericus
-based larvicides. The goal of this work was to investigate the ultrastructural effects of Cry48Aa/Cry49Aa on midgut cells of Bin-toxin-susceptible and -resistant
Culex quinquefasciatus
larvae. The major cytopathological effects observed after Cry48Aa/Cry49Aa treatment were intense mitochondrial vacuolation, breakdown of endoplasmic reticulum, production of cytoplasmic vacuoles, and microvillus disruption. These effects were similar in Bin-toxin-susceptible and -resistant larvae and demonstrated that Cry48Aa/Cry49Aa toxin interacts with and displays toxic effects on cells lacking receptors for the Bin toxin, while
B. sphaericus
IAB59-resistant larvae did not show mortality after treatment with Cry48Aa/Cry49Aa toxin. The cytopathological alterations in Bin-toxin-resistant larvae provoked by Cry48Aa/Cry49Aa treatment were similar to those observed when larvae were exposed to a synergistic mixture of Bin/Cry11Aa toxins. Such effects seemed to result from a combined action of Cry-like and Bin-like toxins. The complex effects caused by Cry48Aa/Cry49Aa provide evidence for the potential of these toxins as active ingredients of a new generation of biolarvicides that conjugate insecticidal factors with distinct sites of action, in order to manage mosquito resistance.
USER Friendly Cloning Coupled with Chitin-Based Natural Transformation Enables Rapid Mutagenesis of
Vibrio vulnificus
Authors: Gulig Paul A. , Tucker Matthew S. , Thiaville Patrick C. , Joseph Jennifer L. , Brown Roslyn N.
Published: June 2009

Vibrio vulnificus
is a bacterial contaminant of shellfish and causes highly lethal sepsis and destructive wound infections. A definitive identification of virulence factors using the molecular version of Koch's postulates has been hindered because of difficulties in performing molecular genetic analysis of this opportunistic pathogen. For example, conjugation is required to introduce plasmid DNA, and allelic exchange suicide vectors that rely on sucrose sensitivity for counterselection are not efficient. We therefore incorporated USER friendly cloning techniques into pCVD442-based allelic exchange suicide vectors and other expression vectors to enable the rapid and efficient capture of PCR amplicons. Upstream and downstream DNA sequences flanking genes targeted for deletion were cloned together in a single step. Based on results from
Vibrio cholerae
, we determined that
V. vulnificus
becomes naturally transformable with linear DNA during growth on chitin in the form of crab shells. By combining USER friendly cloning and chitin-based transformation, we rapidly and efficiently produced targeted deletions in
V. vulnificus
, bypassing the need for two-step, suicide vector-mediated allelic exchange. These methods were used to examine the roles of two flagellin loci (
flaCDE
and
flaFBA
), the
motAB
genes, and the
cheY-3
gene in motility and to create deletions of
rtxC
,
rtxA1
, and
fadR
. Additionally, chitin-based transformation was useful in moving antibiotic resistance-labeled mutations between
V. vulnificus
strains by simply coculturing the strains on crab shells. The methods and genetic tools that we developed should be of general use to those performing molecular genetic analysis and manipulation of other gram-negative bacteria.
Role of the Cell Wall Integrity and Filamentous Growth Mitogen-Activated Protein Kinase Pathways in Cell Wall Remodeling during Filamentous Growth
Authors: Birkaya Barbara , Maddi Abhiram , Joshi Jyoti , Free Stephen J. , Cullen Paul J.
Published: June 2009

Many fungal species including pathogens exhibit filamentous growth (FG) as a means of foraging for nutrients. Genetic screens were performed to identify genes required for FG in the budding yeast
Saccharomyces cerevisiae
. Genes encoding proteins with established functions in transcriptional activation (
MCM1
,
MAT
α
2
,
PHD1
,
MSN2
,
SIR4
, and
HMS2
), cell wall integrity (
MPT5
,
WSC2
, and
MID2
), and cell polarity (
BUD5
) were identified as potential regulators of FG. The transcription factors
MCM1
and
MAT
α
2
induced invasive growth by promoting diploid-specific bipolar budding in haploid cells. Components of the cell wall integrity pathway including the cell surface proteins Slg1p/Wsc1p, Wsc2p, Mid2p, and the mitogen-activated protein kinase (MAPK) Slt2p/Mpk1p contributed to multiple aspects of the FG response including cell elongation, cell-cell adherence, and agar invasion. Mid2p and Wsc2p stimulated the FG MAPK pathway through the signaling mucin Msb2p and components of the MAPK cascade. The FG pathway contributed to cell wall integrity in parallel with the cell wall integrity pathway and in opposition with the high osmolarity glycerol response pathway. Mass spectrometry approaches identified components of the filamentous cell wall including the mucin-like proteins Msb2p, Flo11p, and subtelomeric (silenced) mucin Flo10p. Secretion of Msb2p, which occurs as part of the maturation of the protein, was inhibited by the ß-1,3-glucan layer of the cell wall, which highlights a new regulatory aspect to cell wall remodeling in this organism. Disruption of ß-1,3-glucan linkages induced mucin shedding and resulted in defects in cell-cell adhesion and invasion of cells into the agar matrix.
A Pathogenesis Assay Using
Saccharomyces
cerevisiae
and
C
aenorhabditis
elegans
Reveals Novel Roles for Yeast AP-1, Yap1, and Host Dual Oxidase BLI-3 in Fungal Pathogenesis
Authors: Jain Charu , Yun Meijiang , Politz Samuel M. , Rao Reeta Prusty
Published: June 2009

Treatment of systemic fungal infections is difficult because of the limited number of antimycotic drugs available. Thus, there is an immediate need for simple and innovative systems to assay the contribution of individual genes to fungal pathogenesis. We have developed a pathogenesis assay using
Caenorhabditis elegans
, an established model host, with
Saccharomyces cerevisiae
as the invading fungus. We have found that yeast infects nematodes, causing disease and death. Our data indicate that the host produces reactive oxygen species (ROS) in response to fungal infection. Yeast mutants
sod1
Δ and
yap1
Δ, which cannot withstand ROS, fail to cause disease, except in
bli-3
worms, which carry a mutation in a dual oxidase gene. Chemical inhibition of the NADPH oxidase activity abolishes ROS production in worms exposed to yeast. This pathogenesis assay is useful for conducting systematic, whole-genome screens to identify fungal virulence factors as alternative targets for drug development and exploration of host responses to fungal infections.
MotX and MotY Are Required for Flagellar Rotation inShewanella oneidensisMR-1
Authors: Koerdt Andrea , Paulick Anja , Mock Marlen , Jost Kathinka , Thormann Kai M.
Published: June 2009

The single polar flagellum ofShewanella oneidensisMR-1 is powered by two different stator complexes, the sodium-dependent PomAB and the proton-driven MotAB. In addition,Shewanellaharbors two genes with homology tomotXandmotYofVibriospecies. InVibrio, the products of these genes are crucial for sodium-dependent flagellar rotation. Resequencing ofS. oneidensisMR-1motYrevealed that the gene does not harbor an authentic frameshift as was originally reported. Mutational analysis demonstrated that both MotX and MotY are critical for flagellar rotation ofS. oneidensisMR-1 for both sodium- and proton-dependent stator systems but do not affect assembly of the flagellar filament. Fluorescence tagging of MotX and MotY to mCherry revealed that both proteins localize to the flagellated cell pole depending on the presence of the basal flagellar structure. Functional localization of MotX requires MotY, whereas MotY localizes independently of MotX. In contrast to the case inVibrio, neither protein is crucial for the recruitment of the PomAB or MotAB stator complexes to the flagellated cell pole, nor do they play a major role in the stator selection process. Thus, MotX and MotY are not exclusive features of sodium-dependent flagellar systems. Furthermore, MotX and MotY inShewanella, and possibly also in other genera, must have functions beyond the recruitment of the stator complexes.
Contribution of Citrulline Ureidase toFrancisella tularensisStrain Schu S4 Pathogenesis
Authors: Mahawar Manish , Kirimanjeswara Girish S. , Metzger Dennis W. , Bakshi Chandra Shekhar
Published: June 2009

The citrulline ureidase (CTU) activity has been shown to be associated with highly virulentFrancisella tularensisstrains, including Schu S4, while it is absent in avirulent or less virulent strains. A definitive role of thectugene in virulence and pathogenesis ofF. tularensisSchu S4 has not been assessed; thus, an understanding of the significance of this phenotype is long overdue. CTU is a carbon-nitrogen hydrolase encoded by the citrulline ureidase (ctu) gene (FTT0435) on theF. tularensisSchu S4 genome. In the present study, we evaluated the contribution of thectugene in the virulence of category A agentF. tularensisSchu S4 by generating a nonpolar deletion mutant, the Δctumutant. The deletion of thectugene resulted in loss of CTU activity, which was restored by transcomplementing thectugene. The Δctumutant did not exhibit any growth defect under acellular growth conditions; however, it was impaired for intramacrophage growth in resting as well as gamma interferon-stimulated macrophages. The Δctumutant was further tested for its virulence attributes in a mouse model of respiratory tularemia. Mice infected intranasally with the Δctumutant showed significantly reduced bacterial burden in the lungs, liver, and spleen compared to wild-type (WT) Schu S4-infected mice. The reduced bacterial burden in mice infected with the Δctumutant was also associated with significantly lower histopathological scores in the lungs. Mice infected with the Δctumutant succumbed to infection, but they survived longer and showed significantly extended median time to death compared to that shown by WT Schu S4-infected mice. To conclude, this study demonstrates thatctucontributes to intracellular survival, in vivo growth, and pathogenesis. However,ctuis not an absolute requirement for the virulence ofF. tularensisSchu S4 in mice.
Hopanoids Are Not Essential for Growth of
Streptomyces scabies
87-22
Authors: Seipke Ryan F. , Loria Rosemary
Published: June 2009

Hopanoids are triterpenoic, pentacyclic compounds that are structurally similar to sterols, which are required for normal cell function in eukaryotes. Hopanoids are thought to be an important component of bacterial cell membranes because they control membrane fluidity and diminish passive diffusion of ions, and a few taxons modulate their hopanoid content in response to environmental stimuli. However, to our knowledge, mutational studies to assess the importance of hopanoids in bacterial physiology have never been performed. Genome sequencing of the potato scab pathogen,
Streptomyces scabies
87-22, revealed a hopanoid biosynthetic gene cluster (HBGC) that is predicted to synthesize hopene and aminotrihydroxybacteriohopane products. Hopene was produced by fully sporulated cultures of
S. scabies
on solid ISP4 (International
Streptomyces
Project 4) medium as well as by submerged mycelia grown in liquid minimal medium. The elongated hopanoid aminotrihydroxybacteriohopane was not detected under either growth condition. Transcription of the
S. scabies
HBGC was upregulated during aerial growth, which suggests a link between hopanoid production and morphological development. Functional analysis of the
S. scabies
Δ
hop615
-
1
and Δ
hop615
-
7
mutant strains, the first hopanoid mutants created in any bacterial taxon, revealed that hopanoids are not required for normal growth or for tolerance of ethanol, osmotic and oxidative stress, high temperature, or low pH. This suggests that hopanoids are not essential for normal streptomycete physiology.
Biochemical Evidence for a Timing Mechanism in
Prochlorococcus
Authors: Axmann Ilka M. , Dühring Ulf , Seeliger Luiza , Arnold Anne , Vanselow Jens T. , Kramer Achim , Wilde Annegret
Published: June 2009

Organisms coordinate biological activities into daily cycles using an internal circadian clock. The circadian oscillator proteins KaiA, KaiB, and KaiC are widely believed to underlie 24-h oscillations of gene expression in cyanobacteria. However, a group of very abundant cyanobacteria, namely, marine
Prochlorococcus
species, lost the third oscillator component, KaiA, during evolution. We demonstrate here that the remaining Kai proteins fulfill their known biochemical functions, although KaiC is hyperphosphorylated by default in this system. These data provide biochemical support for the observed evolutionary reduction of the clock locus in
Prochlorococcus
and are consistent with a model in which a mechanism that is less robust than the well-characterized KaiABC protein clock of
Synechococcus
is sufficient for biological timing in the very stable environment that
Prochlorococcus
inhabits.
A New Minimal Replicon ofBacillus anthracisPlasmid pXO1
Authors: Pomerantsev Andrei P. , Camp Andrew , Leppla Stephen H.
Published: June 2009

An 8,883-bp mini-pXO1 plasmid containing a replicon fromBacillus anthracispXO1 (181.6 kb) was identified by making large deletions in the original plasmid using a newly developed Cre-loxPsystem. Portions of the truncated mini-pXO1 were cloned into anEscherichia colivector unable to replicate inB. anthracis. A 5.95-kb region encompassing three putative genes was identified as the minimal pXO1 fragment required for replication of the resulting recombinant shuttle plasmid (named pMR) inB. anthracis. Deletion analysis showed that the only genes essential for replication were the pXO1-14 and pXO1-16 genes, which are transcribed in opposite directions and encode predicted proteins of 66.5 and 67.1 kDa, respectively. The ORF14 protein contains a helix-turn-helix motif, while the ORF16 upstream region contains attributes of a theta-replicating plasmid origin of replication (Ori), namely, an exclusively A+T-containing segment, five 9-bp direct repeats, an inverted repeat, and a σA-dependent promoter for the putative replication initiator Rep protein (ORF16). Spontaneous mutations generated in the ORF14, ORF16, and Ori regions of pMR during PCR amplification produced a temperature-sensitive plasmid that is unable to replicate inB. anthracisat 37°C. The efficacy of transformation of plasmid-freeB. anthracisAmes and Sterne strains by the original pMR was ∼103CFU/μg, whileBacillus cereusstrains 569 and ATCC 10987 were transformed with efficiencies of 104and 102CFU/μg, respectively. Around 95% ofB. anthraciscells retained pMR after one round of sporulation and germination.
IMPROVED APPROXIMATE PROFILE FUNCTION OF HEDGEHOG SKYRMION
Authors: JI YONG-LIN , JIA DUO-JIE , XI GUO-ZHU , LIU FENG
Published: June 2009

The profile function for Skyrme model is investigated in Hedgehog ansatz. An improved analytical solution to the Hedgehog Skyrmion is obtained by using tentative function method. It is found that ensuing calculated static energy is smaller than that in Ref. 13, and the isoscalar electric mean square radius [Formula: see text] and the isoscalar magnetic mean square radius [Formula: see text] well agree with experiment results.
THE ELECTRIC CHARGE ASSIGNMENT INSU(4)L⊗U(1)YGAUGE MODELS
Authors: PALCU ADRIAN
Published: June 2009

In this brief report, apart from the usual approach, we discriminate among models in the class of SU (4)L⊗ U (1)Yelectroweak gauge models by just setting the versors in the general method of treating gauge models with high symmetries. We prove that the method itself naturally predicts the correct assignment of the electric charge spectrum along with the relation between the gauge couplings of the groups involved therein for each particular model in this class.