bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasi-Exact-Constraint Design of Wind Turbine Gearing
Authors: Arafa Hani A. , Bedewy Mostafa
Published: January 2011

In the past two decades the wind turbine industry has witnessed a considerable number of catastrophic accidents, many of which were due to gearbox failure. Ever increasing power ratings at decreased rotor speeds result in rotor torques of some million Nm. This imposes tooth loads and planet/pinion bearing loads on the order of a hundred tons within the first step-up stage. Such heavily loaded gearboxes, correctly (or rather innocently) designed according to the relevant codes, can be self-destructive. Due consideration should be given to the elastic environment in which the gears exist. Otherwise, appreciable, unsymmetrical/unequal elastic deformations in unwanted directions lead to gear tooth edge loading, in addition to overloading the bearing(s) near that edge. Designers of wind turbine gearing have in recent years identified several concepts and measures to be taken for counteracting the asymmetry of elastic deformations or mitigating their effects. In addition to giving a brief survey of such new design concepts, this paper suggests the use of selected types of curved-tooth cylindrical gears (so-called C-gears), primarily for their self-aligning capability; they allow four degrees of freedom (4-DOF), in contrast to the 3-DOF spur and helical gears and the 2-DOF double-helical gears. In addition, these gears offer a unique set of further advantages. When used in at least the most heavily loaded, first step-up stage, the design will be rendered quasi-exactly constrained; largely tolerant of misalignment due to elastic deformations, and the gearbox reliability should be improved, by design.
Design of Nuclear Safety-Related Underground Diesel Fuel Oil Storage Tanks
Authors: Wang Shen , Akinci Necip O. , Johnson William H. , Moreschi Luis M.
Published: January 2011

Diesel fuel oil storage tanks are critical components for safety of nuclear power plants. Proper functioning of the emergency diesel generators during an earthquake depends on the fuel oil supplied from the storage tank. Failure of the tank, nozzles or fuel pipes can result in contamination and/or leakage of the fuel. The allowable stress limits and design charts for above ground tanks, which are provided in the ASME Boiler and Pressure Vessel Code for a pressure vessel, are occasionally adopted in the design of underground tanks. However, the analytical methodology for evaluation of stresses in the buried tanks requires detailed analysis different from that for a typical pressure vessel. Soil-structure and fluid-structure interaction effects need to be considered in the analysis for simulation of the actual static and seismic loads. Therefore, advanced simulation techniques and finite element analysis tools have been used by several researchers to evaluate buried tanks. Simple, but acceptably accurate techniques for comprehensive evaluation of underground storage tanks have not been established. This study presents simplified evaluation techniques for a diesel fuel storage tank using fundamental concepts. The diesel fuel oil storage tanks considered here are cylindrical and oriented with their axes in the horizontal direction. The static overburden and seismic pressures cause ovaling of the tank and generate significant bending stresses, which are not addressed in the pressure vessel design approach. The simplified tank evaluation proposed here includes the ovaling effect under static overburden, seismic and sloshing loads. Earthquake induced stresses in hoop and longitudinal directions are calculated using the free field approach and the classical Housner Method is employed in the sloshing analysis. Allowable stress and buckling of the tank wall are checked against corresponding criteria.
Project Risk Based Estimate and Management
Authors: Cretu Ovidiu , Gabel Mark , Cretu Vlad
Published: January 2011

The paper presents the use of Risk Based Estimate (RBE) process and Risk Based Estimate Self-Modeling (RBES) eliminating the need of specialized software by allowing a regular MS Excel users to develop an integrated cost and schedule estimate with limited knowledge of risk analysis. The RBES offers the flexibility of entering: • The base project cost and schedule with different degrees of uncertainty associated with them; • Independent risks with both components: cost and duration; • Sophisticated risks which are dependent on each other and/or correlated. • Specific escalation rates for Real Estate acquisition, Preliminary Engineering (PE), and Construction (CN). • Risk response actions so that a “post-mitigated” analysis can also be conducted. Model outputs include graphs (Histograms and Cumulative Distribution Functions), and tables that present the project cost estimate range in current year dollars, and year of expenditure dollars for the three main phases of project delivery (PE, Real Estate, CN); RBES model output also includes the estimated ranges for the Advertisement date, and the End Construction date. In addition the RBES produces tornado diagrams of the most significant cost and schedule risks, and the risks map in order to help the project risk management efforts.
Analysis of Combustion Flame of Syngas-Air Mixtures
Authors: Monteiro Eliseu , Rouboa Abel
Published: January 2011

In the proposed paper for this conference, three typical mixtures of H2, CO, CH4, CO2 and N2 have been considered as representative of the producer gas (syngas) resulting from biomass gasification. Syngas is being recognized worldwide as a viable energy source, particularly for stationary power generation. However, there are gaps in the fundamental understanding of syngas combustion characteristics, particularly at elevated pressures that are relevant to practical combustors. In this work, constant volume spherical expanding flames of three typical syngas compositions have been employed to measure the laminar burning velocity for pressures ranges between 1.0 and 20 bar. Over the ranges studied, the burning velocities are fitted by the functional formula of Metghalchi and Keck. Conclusion can be drawn that the burning velocity decreases with the increase of pressure. In opposite, the increase of temperature induces the increase of burning velocity. The higher burning velocity value is obtained for the downdraft syngas. This result is endorsed to the higher heat value, lower dilution and higher volume percentage of hydrogen in the downdraft syngas.
Performance Prediction of a Single-Zone Vertical Feedwater Heater
Authors: Svensson Eric , Mirowski William
Published: January 2011

This paper represents a case study of a replacement single-zone vertical feedwater heater with a pump forward drains system. When replacing a feedwater heater, it is important to review, evaluate and adjust the NLL of the new heater since it may not be the same as the NLL of the existing heater in order to achieve the same performance, particularly when changing the tube material. This paper strives to explain a method that was used in order to predict changes in both the feedwater and drains outlet temperatures based on varying liquid level. Single-zone feedwater heaters are typically sized and rated with a drains outlet temperature that is equal to the saturation temperature of the incoming bleed steam. Depending on the normal liquid level (NLL) setpoint, there is some subcooling that occurs due to the submerged tube surface that is typically not accounted for in the heater rating, this is especially true in a vertical channel down configuration. The outlet drains of a condensing zone only heater are still required to be safely transported in the liquid state to either another heater or to the condenser, therefore an adequate amount of subcooling is desired in order to preclude flashing and two-phase flow from occurring within the drains piping. The amount of subcooling that can be expected is related to the amount of surface that is submerged and therefore is directly tied to the liquid level inside the heater. Intuitively, more subcooling can be achieved by raising the liquid level; however, this has the effect of reducing the surface area available for condensation and ultimately the feedwater outlet temperature. In a pump forward drains system, this has an additional negative effect in that the drains are then combined with the outlet feedwater and reduces the feedwater temperature further prior to entering the next heater. It was desired to optimize the normal liquid level such that the drains outlet temperature would be subcooled enough to protect the downstream heater drain pump, but not to raise the level to a point that would significantly lower the inlet temperature to the next feedwater heater, resulting in inefficiencies in the overall heat cycle and overloading the downstream heater.
Combustion Optimization for Increased Fuel Flexibility
Authors: Kirkenir Bill , Earley Dave
Published: January 2011

Progress Energy has incorporated on-line combustion optimization/tuning to lower LOI and eliminate furnace reducing atmospheres at several of their North Carolina Plants. The optimization projects utilized individual burner airflow measurement, continuous burner coal flow measurement and coal balancing valves to adjust burner air to fuel ratios. The DCS systems were modified to allow control of mass flow of air to each overfire air port as well as air to fuel ratio control of each burner. This was accomplished for the purpose of increasing Fuel Flexibility without impacting boiler and unit reliability. The objectives of the projects were to eliminating furnace reducing atmospheres and the resultant tube deterioration while improving fuel flexibility without negatively impacting boiler reliability. Other desired benefits included NOx reduction, decreased LOI, efficiency improvement and minimized boiler fouling. The focus of this paper is on the benefits and results experienced on the Asheville #2 unit. The furnace oxygen level through the combustion changes improved ∼334% while LOI decreased. The paper will also discuss the other improvements to the unit that were achieved by using the new air and fuel flow controls in the DCS. The paper will also outline additional improvements in the information available to unit operators, unit engineers and remote engineers.
Experimental Investigation of Seawater Fouling Effect on the 90/10 Cu/Ni Tube
Authors: Izadi M. , Aidun D. K. , Marzocca P. , Lee H.
Published: January 2011

The fouling effect of seawater on a 90/10 Cu/Ni commercial heat exchanger tube is investigated. A fouling monitoring device, designed on the basis of fouling thermal resistance, is used for the current experimental study. First, the seawater samples collected in different times from Hampton, Rye, and Wallis beaches in New Hampshire, USA are vacuum-filtered down to a 10 μm filter paper to remove suspended solids, micro-organisms, and the majority of biological spores. Then, the filtered seawater samples are circulated through the closed loop experimental setup for two weeks and the fouling thermal resistance is measured continuously. The results show different fouling behavior for the seawater samples confirmed by the different composition of the samples. Analytical microscopy is performed on the tube surface before and after the experiments to see the effect of seawater fouling on the tube surface. The results of fouling monitoring experiments reveal a higher fouling thermal resistance for one of the seawater samples, Hampton seawater, contrary to the results of SEM\EDS analysis which show lower crystallization for Hampton sample. Water decomposition analysis shows the lowest sodium content for Hampton seawater compared to the other samples. Accordingly, accelerated corrosion of the tube surface occurs for Hampton seawater due to the presence of chlorine ions and low concentration of sodium. The high fouling resistance of Hampton seawater can be explained by participation of several fouling mechanisms simultaneously which makes a composite fouling behavior for Hampton seawater sample. The results of the current study are critical for the industries which use seawater as the cooling water source.
Stress and Vibration Analysis for Woven Composite Axial Impeller
Authors: Wang Jifeng , Olortegui-Yume Jorge , Mu¨ller Norbert
Published: January 2011

A stress and vibration analysis procedure is developed to assess the static and dynamic characteristics of the Woven Composite Axial-Impeller under loading conditions particular to centrifugal force. This procedure is based on Finite Element Analysis (FEA, commercial software ABAQUS) results. A low-cost, light-weight, high-performance, composite turbomachinery impeller with uniquely designed blade patterns are evaluated. Understanding the stress-strain behavior of fiber composite laminates to ultimate failure and the ability to predict ultimate strength is critical in the design of safe and lightweight impellers. To determine failures, the maximum stress failure criterion is used. In order to avoid resonance which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of impeller to analyze the dynamic characteristics. The results show that composite material Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed of 450m/s and withstand the stresses; no critical speed will be matched during start-up and shut-down and that mass imbalances of the impeller shall not pose a critical problem.
Power Perfomance Tests on a Different Wind Turbine Rotor Blade Design
Authors: Amano Ryo , Avdeev Ilya , Malloy Ryan , Shams Mir Zunaid
Published: January 2011

Most blades available for commercial grade wind turbines incorporate a straight, span-wise profile and airfoil-shaped cross-sections. These blades are found to be very efficient at low and medium wind speeds compared with the potential energy that can be extracted. This paper explores the possibility of increasing the efficiency of the blades by modifying the blade design to incorporate a swept edge. The design intends to maintain efficiency at low to medium wind speeds by selecting the appropriate orientation and size of the airfoil cross-sections based on an oncoming wind speed and given constant rotation rate. The torque generated from a blade with straight edge geometry is compared with that generated from a blade with a swept edge as predicted by CFD simulations. To validate the simulations, the experimental curve of the NTK500/41 turbine using LM19.1 blades will be reproduced using the same computational conditions. In addition, structural deformations, stress distributions, and structural vibration modes are compared between these two different turbine blade surfaces.
A Review of Experiences With AL-6XN® and Zeron® 100 Alloys in Air Pollution Control Systems
Authors: Wachowiak Devin M. , Wilson Jason D.
Published: January 2011

Coal fired power plants are faced with increasingly strict air quality control laws and EPA rules. New multi-pollutant legislation is controlling a wider range of emissions, especially sulfur compounds. A significant number of flue gas desulfurization (FGD) units worldwide employ wet scrubbing to reduce sulfur dioxide emissions by more than 90 percent. Wet scrubbing has also been found to be effective at removing mercury in many cases. Due to the inherent contaminants generated by the combustion of coal, wet FGD’s require the use of corrosion resistant materials in their construction. A variety of metallic corrosion resistant alloys are currently used in these pollution control systems. This paper will review the use of AL-6XN and Zeron 100 alloys in various FGD applications around the world. Examples of AL-6XN and Zeron 100 in actual service in FGD units will be presented. AL-6XN and Zeron 100 are alloys that have been chosen for these systems when conditions are too severe for either 316L stainless steel or 2205 duplex stainless steel. Experimental data will be reviewed that supports the use of these alloys in the high chloride containing environments encountered by the many components of the pollution control systems. AL-6XN and Zeron 100 alloys have proven to be cost effective materials of construction that fill the gap between the lower alloyed stainless steels such as 317L, 904L, and 2205, and the high molybdenum and nickel based alloys such as C-276. As AL-6XN and Zeron 100 alloys are established materials of construction, they are readily available in product forms necessary to complete an FGD system.
Determining HP-IP Turbine Seal Leakage
Authors: Lang Fred D. , Canning Tom
Published: January 2011

This paper presents a new method for determining turbine shaft seal leakages. Specifically the seals are those which flow from the High Pressure (HP) turbine to the Intermediate Pressure (IP) turbine when these machines share the same cylinder. This work began with the well-known Booth/Kautzmann Method, also known as an “Influence Test”. The work was instigated given that routine success of Booth/Kautzmann has not always been assured. This work promotes two major modifications. First, an improvement is advocated in which the contribution from seal flows is weighted based on source energies; i.e., use of a strictly defined thermodynamic boundary. This applies to isentropes and exergy differences. However, the use of weighted isentropes does not guarantee that Booth/Kautzmann will always work. Second, the use of a convergence parameter is advocated which normalizes the influence of differing Reheat flows. This convergence parameter leads to a consistently computed seal flow which is quite suitable for routine monitoring. The new technique has a remarkable ability to detect inconsistent data. Four case studies are presented: two conventional North American designs in which the HP seal is placed between the Governing Stage shell and 2nd HP stage group (termed the “Dummy Seal” or “N2 Packing” leakage); and two European designs in which the HP seal is exposed to turbine inlet conditions. Although several of these studies produced sharp convergences using Booth/ Kautzmann with weighted isentropes, this work places doubt on their reliability. Comments are offered on the technique’s use, data reduction procedures and on further development. A sample spreadsheet has been made available for use by power engineers.
Review of Babbitt (Whitemetal) Analysis Using XRF-Analyzer
Authors: Branagan Lyle A. , Herran Greg
Published: January 2011

One possible application for portable X-ray fluorescence (XRF) analysis is to improve the verification of babbitt composition, including babbitt after casting. Variations of babbitt (whitemetal) composition are a concern in some critical applications of fluid-film bearings and material verification could provide another useful tool. A particular commercial XRF analyzer was applied to babbitt during different stages of bearing manufacture. A test protocol of ten samples, eight seconds per sample, at each test point was developed to minimize the standard deviation of the reported results. Comparisons with “wet” chemical testing showed considerable variation, particularly for the trace element of lead.
Mitigation of Fires in Coal-Handling Facilities: Continuous Monitoring of Carbon Monoxide
Authors: Smoker Kurt , Albinger Rob
Published: January 2011

While many power companies across the country rely on coal-burning facilities, fires and explosions in coal-handling facilities are of increasing concern. While facility housekeeping by means of controlling dust and preventing spills is very important, a good risk management plan must also include continuous monitoring of toxic and combustible gases. The use of carbon monoxide gas detectors has proved for years to be a very effective early fire detection system. This paper describes a risk-management system that can greatly mitigate the possibility of fire by means of alarming at low levels of CO concentration. The authors present a pro-active approach, focusing not on detecting smoke, which indicates fire, but rather on detecting CO, which indicates the potential for fire. Covered are the benefits of CO monitoring over thermal monitoring and IR scanning, the importance of monitoring for any continual trend upward from background levels, and discussion of how proper alarm setpoints are determined, using case studies.
Laminar Flame Velocity of Syngas Fuels
Authors: Dam Bidhan , Ardha Vishwanath , Choudhuri Ahsan
Published: January 2011

The paper presents the experimental measurements of the laminar burning velocity of H2-CO mixtures. Hydrogen (H2) and carbon monoxide (CO) are the two primary constituents of syngas fuels. Three burner systems (nozzle, tubular, and flat flame) are used to quantify the effects of burner exit velocity profiles on the determination of laminar flame propagation velocity. The effects to N2 and CO2 diluents have been investigated as well, and it is observed that the effects of N2 and CO2 on the mixture burning velocity are significantly different. Finally, the burning velocity data of various syngas compositions (brown, bituminous, lignite and coke) are presented.
Xcel Energy Riverside Repowering Project
Authors: Eiden Paul , Rathsam Tim , Schottler Darin
Published: January 2011

Xcel Energy’s Riverside Repowering Project was a voluntary emissions reduction project with the goals of improving air quality in Minnesota while, at the same time, increasing the amount of electricity produced. The Riverside Plant was converted from being a coal-fired facility to a combined-cycle facility firing natural gas. The fuel switch resulted in significant plant emission benefits, with emissions of sulfur dioxide decreasing by 99%, nitrogen oxides (NOx) decreasing by 96%, and mercury being eliminated entirely. Plant output increased from a nominal generating capacity of 386 MW to a summer day net output of 472 MW. The three existing coal-boilers were retired. Two F-technology combustion turbine generators (CTGs) and two heat recovery steam generators (HRSGs) were installed. Each CTG fires natural gas with dry low-NOx combustors. Each HRSG includes a selective catalytic reduction (SCR) section supplied with aqueous ammonia. Steam generated from the HRSGs is fed to an existing steam turbine. The low-pressure steam from the HRSG is admitted into the steam turbine through a new connection. The steam turbine extraction lines for feedwater heating are capped. To accommodate the resulting increased flow through the turbine, two rows of blades were replaced. A new full-flow steam turbine bypass system operates during plant startup and shutdown. An auxiliary boiler was added to provide warming and sealing steam to the steam turbine. A new distributed control system (DCS) operates the facility, with workstations located in the plant’s existing control room. The existing once-through circulating water system on the Mississippi River was modified with the addition of wedgewire screens to comply with the Clean Water Act Section 316(b). The CTGs and HRSGs are fully enclosed in a new building that is integrated with the structure for the steam turbine. Due to the proximity of residential housing, sound attenuation is critical. Space for the new building was created by demolishing formerly retired units. Reclaiming this area resulted in a unique layout. The HRSGs are constructed over wood piles installed in 1914–22. The HRSG foundation consists of an elevated slab supported on concrete walls distributing load to the original pile caps. Between the HRSGs and the CTGs are retired concrete coal hoppers that divide the site. The CTGs sit approximately 20 feet higher than the base of the HRSGs. The combined cycle achieved commercial operation on May 1, 2009.
Cleaning of GaN(2¯110) surfaces
Authors: Schulz Ch. , Kuhr S. , Geffers H. , Schmidt Th. , Flege J. I. , Aschenbrenner T. , Hommel D. , Falta J.
Published: January 2011

The cleaning of GaN(2¯110) surfaces was investigated by x-ray photoelectron spectroscopy, scanning tunneling microscopy, and low-energy electron diffraction. Two different two-step cleaning methods, performed under ultrahigh-vacuum conditions, were carried out and compared. The first cleaning step of both methods is thermal degassing. The second step is either the deposition of metallic gallium followed by redesorption or an exposure to active nitrogen from a radio frequency nitrogen plasma source. Upon storage in a glovebox (N2 atmosphere) and transfer to ultrahigh vacuum under dry nitrogen, carbon and oxygen were identified as the major contaminants. A significant decrease in oxygen and carbon was achieved by thermal degassing at 750 °C under ultrahigh-vacuum conditions. By applying a subsequent Ga deposition/redesorption or N2-plasma cleaning step, a further reduction in oxygen and carbon could be achieved. In comparison, the Ga deposition/redesorption cleaning showed a better performance in oxygen removal, whereas the N2 plasma exhibits a better efficiency in carbon removal. Furthermore scanning tunneling microscopy and low-energy electron diffraction investigations showed a drastic improvement of the morphology and atomic structure of the clean surfaces in contrast to the sample surfaces after N2 storage and transfer.
Direct growth of hexagonal InN films on 6H-SiC by radio-frequency metal-organic molecular-beam epitaxy
Authors: Chen Wei-Chun , Kuo Shou-Yi , Hsiao Chien-Nan , Tsai Din Ping
Published: January 2011

Wurtzite InN films were prepared on a 6H-SiC substrate by a self-designed plasma-assisted metal-organic molecular-beam epitaxy system without a buffer layer. In this article, the authors investigate the structural and optical properties of InN films grown on a 6H-SiC substrate. The crystallinity and microstructure of the thin film were further characterized by x-ray diffraction (XRD), field-emission scanning-electron microscopy, and transmission-electron microscopy. Electrical and optical properties were evaluated by Hall and photoluminescence (PL) measurements. XRD results indicate that InN film grown at 500 °C is epitaxially grown along the c-axis orientation. The two-dimensional growth mode is clearly shown in scanning-electron microscope images. Room-temperature PL spectra show that the emission peak is located at ∼0.83 eV due to the Burstein–Moss effect. In addition, the crystalline InN samples crack and peel away from the substrate at elevated growth temperature. This phenomenon may be attributed to lattice mismatch and grain coalescence while increasing the growth temperature. The narrow window of the growth temperature plays an important role in engineering the InN epitaxial growth.
Aspects of fast load lock designs in vacuum manufacturing equipment
Authors: Bijker M. D. , Bosch R. C. M. , Conrad A.
Published: January 2011

In order to increase throughput on vacuum deposition tools, fast load locking strategies are essential. In this article, an overview of fast two pumpdown strategies is discussed. Both a solution based on a turbo pump as well as a new type of booster pump is reviewed. A detailed theoretical description is given, dealing with pump speed calculations at continuous flow, free molecular flow, and the transition pressure region, which is very important to determine the final load lock pumpdown time.
When does hot water freeze faster then cold water? A search for the Mpemba effect
Authors: Brownridge James D.
Published: January 2011

It is possible to consistently observe hot water freezing faster than cold water under certain conditions. All conditions except the initial temperature of water specimens must be the same and remain so during cooling, and the cold water must supercool to a temperature significantly lower than the temperature to which the hot water supercools. For hot water at an initial temperature of >≈80 °C and cold water at <≈20 °C, the cold water must supercool to a temperature of at least ≈5.5 °C, lower than the temperature to which hot water supercools. With these conditions satisfied, we observed initially hot water freezing before the initially cold water 28 times in 28 attempts. If the cold water does not supercool, it will freeze before the hot water because it always cools to 0 °C first regardless of the initial temperatures.
Global Tissue Revolutions in a Morphogenetic Movement Controlling Elongation
Authors: Haigo Saori L. , Bilder David
Published: January 2011

The ellipsoid shape of the
Drosophila
egg is controlled by global tissue revolutions that polarize the matrix.
Discovery of Powerful Gamma-Ray Flares from the Crab Nebula
Authors: Tavani M. , Bulgarelli A. , Vittorini V. , Pellizzoni A. , Striani E. , Caraveo P. , Weisskopf M. C. , Tennant A. , Pucella G. , Trois A. , Costa E. , Evangelista Y. , Pittori C. , Verrecchia F. , Del Monte E. , Campana R. , Pilia M. , De Luca A. , Donnarumma I. , Horns D. , Ferrigno C. , Heinke C. O. , Trifoglio M. , Gianotti F. , Vercellone S. , Argan A. , Barbiellini G. , Cattaneo P. W. , Chen A. W. , Contessi T. , D’Ammando F. , DeParis G. , Di Cocco G. , Di Persio G. , Feroci M. , Ferrari A. , Galli M. , Giuliani A. , Giusti M. , Labanti C. , Lapshov I. , Lazzarotto F. , Lipari P. , Longo F. , Fuschino F. , Marisaldi M. , Mereghetti S. , Morelli E. , Moretti E. , Morselli A. , Pacciani L. , Perotti F. , Piano G. , Picozza P. , Prest M. , Rapisarda M. , Rappoldi A. , Rubini A. , Sabatini S. , Soffitta P. , Vallazza E. , Zambra A. , Zanello D. , Lucarelli F. , Santolamazza P. , Giommi P. , Salotti L. , Bignami G. F.
Published: January 2011

Gamma-ray observations of the Crab Nebula by two different space telescopes challenge particle acceleration theory.
2010: Signaling Breakthroughs of the Year
Authors: Adler Elizabeth M.
Published: January 2011

The editors highlight the year's cell signaling breakthroughs.
Exiting the Birthplace
Authors: Hines Pamela J.
Published: January 2011

A ubiquitination cascade regulates formation of cell adhesions that immature neurons require in the developing mouse brain.
Immune Protection from Metabolic Syndrome?
Authors: Gough Nancy R.
Published: January 2011

An immune profile that is biased toward the T
H
2 anti-inflammatory side regulates hepatic metabolism and limits adipose inflammation.
Susceptibility of Clinical
Mycobacterium tuberculosis
Isolates to a Potentially Less Toxic Derivate of Linezolid, PNU-100480
Authors: Alffenaar J. W. C. , van der Laan T. , Simons S. , van der Werf T. S. , van de Kasteele P. J. , de Neeling H. , van Soolingen D.
Published: January 2011

Susceptibility of clinical
Mycobacterium tuberculosis
isolates to PNU-100480 and linezolid was evaluated by the MGIT 960 system. The isolates had various susceptibilities to isoniazid (INH), rifampin, ethambutol, and streptomycin. The mean MIC for PNU-100480 was 3.2 times lower than that for linezolid. Therefore, PNU-100480 is a promising candidate to be developed further as an adjunct in the treatment of multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB).
Desbutyl-Lumefantrine Is a Metabolite of Lumefantrine with Potent
In Vitro
Antimalarial Activity That May Influence Artemether-Lumefantrine Treatment Outcome
Authors: Wong Rina P. M. , Salman Sam , Ilett Kenneth F. , Siba Peter M. , Mueller Ivo , Davis Timothy M. E.
Published: January 2011

Desbutyl-lumefantrine (DBL) is a metabolite of lumefantrine. Preliminary data from
Plasmodium falciparum
field isolates show greater antimalarial potency than, and synergy with, the parent compound and synergy with artemisinin. In the present study, the
in vitro
activity and interactions of DBL were assessed from tritium-labeled hypoxanthine uptake in cultures of the laboratory-adapted strains 3D7 (chloroquine sensitive) and W2mef (chloroquine resistant). The geometric mean 50% inhibitory concentrations (IC
50
s) for DBL against 3D7 and W2mef were 9.0 nM (95% confidence interval, 5.7 to 14.4 nM) and 9.5 nM (95% confidence interval, 7.5 to 11.9 nM), respectively, and those for lumefantrine were 65.2 nM (95% confidence interval, 42.3 to 100.8 nM) and 55.5 nM (95% confidence interval, 40.6 to 75.7 nM), respectively. An isobolographic analysis of DBL and lumefantrine combinations showed no interaction in either laboratory-adapted strain but mild synergy between DBL and dihydroartemisinin (sums of the fractional inhibitory concentrations of 0.92 [95% confidence interval, 0.87 to 0.98] and 0.94 [95% confidence interval, 0.90 to 0.99] for 3D7 and W2mef, respectively). Using a validated ultra-high-performance liquid chromatography-tandem mass spectrometry assay and 94 day 7 samples from a previously reported intervention trial, the mean plasma DBL was 31.9 nM (range, 1.3 to 123.1 nM). Mean plasma DBL concentrations were lower in children who failed artemether-lumefantrine treatment than in those with an adequate clinical and parasitological response (ACPR) (
P
= 0.053 versus
P
> 0.22 for plasma lumefantrine and the plasma lumefantrine-to-DBL ratio, respectively). DBL is more potent than the parent compound and mildly synergistic with dihydroartemisinin. These properties and the relationship between day 7 plasma concentrations and the ACPR suggest that it could be a useful alternative to lumefantrine as a part of artemisinin combination therapy.
Airborne bacteria concentrations and related factors at university laboratories, hospital diagnostic laboratories and a biowaste site
Authors: Hwang Sung Ho , Park Dong Uk , Ha Kwon Chul , Cho Hyun Woo , Yoon Chung Sik
Published: January 2011

Aims

To evaluate concentrations of airborne bacteria in university laboratories, hospital diagnostic laboratories, and a biowaste site in Seoul, Korea. To measure total airborne bacteria (TAB), the authors assessed sampling site, type of ventilation system, weather and detection of Gram-negative bacteria (GNB), indoors and outdoors.

Method

An Andersen one-stage sampler (Quick Take 30; SKC Inc) was used to sample air at a flow rate of 28.3 l/min for 5 min on nutrient medium in Petri dishes located on the impactor. A total of 236 samples (TAB, 109 indoor and nine outdoor; GNB, 109 indoor and nine outdoor) were collected three times in each spot from the 11 facilities to compare airborne bacteria concentrations.

Results

TAB concentrations ranged from undetectable to 3451 CFU/m3(mean 384 CFU/m3), and GNB concentrations from undetectable to 394 CFU/m3(mean 17 CFU/m3). TAB concentrations were high in window-ventilated facilities and facilities in which GNB were detected; concentrations were also high when it was rainy (all p values <0.05). TAB concentrations correlated significantly with GNB (r=0.548, p<0.01), number of bacteria species (r=0.351, p<0.01) and temperature (r=0.297, p<0.01). The presence of heating, ventilating, and air conditioning (HVAC), the number of TAB species and the detection of GNB affect TAB concentrations in laboratories.

Conclusions

It is recommended that special attention be given to regular control of indoor environments to improve the air quality of university and hospital laboratories.
Some Properties of a Finite Cell Line from Beluga Whale (Delphinapterus leucas)
Authors: Nielsen O. , Kelly R. K. , Lillie W. R. , Clayton J. W. , Fujioka R. S. , Yoneyama B. S.
Published: January 2011

A finite cell line (BWK) was derived from kidney of an immature male beluga whale (Delphinapterus leucas). Cells were grown for 19 ± 1 passages at 37 °C in enriched tissue culture media supplemented with 10% fetal bovine serum and containing antibiotics. The cell line had a diploid chromosome modal number (2n = 44), but a pseudodiploid karyotype. BWK cells were characterized by lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucosephosphate isomerase (GPI), and phosphoglucomutase (PGM) isozyme systems. The cells were susceptible to infection by several mammalian viruses including coxsackievirus (B3 and B5), vaccinia, and herpes simplex 1; but were refractory to echovirus 27, influenza A, poliovirus (types 1 and 3), and simian agent 11. The BWK line, which has been stored in liquid nitrogen, appears to be suitable for isolation of viruses from marine mammals.
Size Distribution of the Macroinvertebrate Community in a Freshwater Lake
Authors: Hanson John Mark , Prepas E. E. , Mackay William C.
Published: January 2011

Macroinvertebrates were collected every 2 wk for 18 wk from three depth zones in a deep lake in Alberta. Unionid clams comprised 80% of the total macroinvertebrate biomass and were excluded from initial analyses. The seasonal average size-spectrum for the littoral zone community was bimodal with peaks in the 8–16 and 256–512 mg weight-classes; size-spectra for the sublittoral and profundal communities were unimodal with peaks in the 8–16 and 16–32 mg weight-classes, respectively. Slopes of the normalized size-spectra for the littoral, sublittoral, profundal and whole-lake communities were not significantly different from −1.0, −1.0, 0.0, and −1.0, respectively. These results suggest that biomass is evenly distributed across logarithmically even size-classes for the average macroinvertebrate community in the littoral zone, sublittoral zone, and on a whole-lake basis. The biomass peak for unionids (16.4–32.8 g weight-class) was 10–30 times greater than biomass peaks for the remaining macroinvertebrates. The slopes of normalized size-spectra for the littoral zone and whole-lake were changed significantly when unionids were included; however, unionids presumably play a minor role in the macroinvertebrate community because they are an energy sink in the present context. Despite wide seasonal variation, average normalized size-spectra based on samples collected at 4- and 6-wk intervals were very similar to those based on nine biweekly collections.
Environmental Complexity and the Drifting Behaviour of a Running Water Amphipod
Authors: Williams D. Dudley , Moore Kathryn A.
Published: January 2011

Overall level and type of activity of Gammarus pseudolimnaeus changed with current speed and pattern in laboratory stream tanks. With increasing current speed (15 to 28 cm/s) active and passive downstream transport increased whereas numbers of animals moving upstream decreased. Upstream movement increased in smooth and rough flow above 28 cm/s. Mean swimming speeds of individuals differed between day and night at most current settings. Total distances drifted by single animals were greater in 43-L ("macroenvironments") than in 3. 5-L stream tanks ("microenvironments"), and were greater in both environments at night On average, individuals had 6.8 drift episodes during 12 h darkness in microenvironments (nightly downstream displacement 3.04 m), compared with 37.9 episodes in macroenvironments (displacement 22.4 m). Level of activity was positively related to amphipod benthic density during both day and night in microenvironments; however, in macroenvironments at night the relationship was negative. Cessation of drift in the presence of fish predators and marked nocturnal activity peaks in macroenvironments were absent in microenvironments. The different responses within the two environments may reflect differences in perception of local environmental scale by the amphipods. This process may occur during the periodic contacts that animals make with the substrate during drift; individuals may retain some familiarity with features of their immediate surroundings.
Influence of Cover Complexity and Current Velocity on Winter Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch)
Authors: McMahon Thomas E. , Hartman Gordon F.
Published: January 2011

Winter habitat use by juvenile coho salmon (Oncorhynchus kisutch) varied with cover type and flow level in outdoor stream channels. Cover utilization and the number of fish remaining in stream channels increased significantly as cover complexity increased. Most fish emigrated during a simulated freshet unless the most complex cover (low velocity, shade, and wood debris combined) was available. At both high and low flows, emigration occurred primarily during the rapid decline in light levels at twilight. Most coho formed aggregations beneath cover, exhibiting feeding and aggression at temperatures as low as 2.5 °C. We conclude that (1) social interactions, in concert with habitat features, influence the abundance of coho salmon within specific stream habitats in winter, and (2) structural complexity of wood debris is an important consideration for management practices designed to protect or enhance winter habitat for this species.
Comparison of Heavy Metals in Two Groups of Ringed Seals (Phoca hispida) from the Canadian Arctic
Authors: Wagemann R.
Published: January 2011

Heavy metals (Pb, Hg, Cd, Cu, and Zn) and Se and As were determined in liver, kidney, and muscle of ringed seals captured near a lead–zinc mine in the Strathcona Sound area, and in a reference group from Admiralty Inlet in the Canadian Arctic. The mean concentrations of Pb in liver and muscle and Se in muscle were higher in seals shot near the mine area than in a reference group shot 50–75 km from this area, notwithstanding large variances in metal concentrations arising from inter-metal and Hg–age and Cd–age positive correlations. Strong positive correlations were found between age of animals in the reference group and Cd in kidney and Hg in liver between Se and Hg in liver, and a negative one between age and Cu in the three tissues examined. Nearly halt of the individuals in the mine-area group were shown, by multiple linear regression, to have higher Hg, Pb, or Cd than the reference group. High Cd concentrations were found in tissues of seals from both groups.
A Model for Standardizing Dungeness Crab (Cancer magister) Catch Rates among Traps which Experienced Different Soak Times
Authors: Smith Barry D. , Jamieson Glen S.
Published: January 2011

The abundance and size frequency distribution (SFD) of Dungeness crabs (Cancer magister) within traps varies with soak time. Such bias in catch rates was reduced using a standardization model that corrected for (1) changes in bait effectiveness over time and (2) agonistic interactions between crabs within traps and those attempting entry. The model estimated the entry and exit of crabs based on the results of trapping experiments specifically designed to (1) emphasize the above two processes and (2) estimate escapement rates from traps for crabs of different sizes. Results clearly indicated the importance of these two processes in modifying trap contents over time, and led to the introduction of the term 'virtual catch rate' (VCR), defined as the rate at which crabs would enter a trap if catch rates did not change with increasing soak time. VCRs are not observed in practice except perhaps for very short soak times, but can be estimated from trap samples by incorporating the aforementioned processes into a standardization model. We found VCR to be a better index of abundance than mean daily catch per trap, and believe it may have utility for other trap fisheries.
Exploitation and Mortality of Male Dungeness Crabs (Cancer magister) Near Tofino, British Colombia
Authors: Smith Barry D. , Jamieson Glen S.
Published: January 2011

Male Dungeness crabs (Cancer magister) were sampled by traps and monitored by tagging as they moulted and entered the fishery near Tofino, British Columbia, from April 1985 until March 1987. Males first recruited to the fishery after moulting from the μ = 129-mm CW (carapace width) to the μ = 156-mm CW normal instar. Sublegalsized males (< 154 mm notch-to-notch CW) in the μ = 156-mm CW instar (≈ 42% of this instar) were found to have a high annual natural mortality (M = 2.9–4.5), with < 10% surviving to legal size. Legal-sized males experienced high annual fishing mortality (F = 5.1–6.9), so consequently a small component of the commercial catch consisted of males in larger instars. Size frequency analysis, which measured the percent exploitation of the μ = 156-mm CW instar, indicated that legal-sized males remained in relatively low abundance during this year-round fishery because of intense exploitation. Mark–recovery data and size frequency analysis also indicated this intense fishery was sustained throughout most of the year by a protracted moulting season. Consequently, we observed prolonged periods with a high percentage of less desirable soft-shelled males in the commercial catch.
Behavioural Response of the Lobster Homarus americanus to Traps
Authors: Karnofsky Elisa B. , Price Holly J.
Published: January 2011

A 180-m2 tank was set up as a semi-natural benthic habitat in order to obtain quantitative visual observations on the behavioural response of lobsters to traps. The wood-lath parlour traps commonly used in the lobster fishery were very inefficient; only 2% of approaches to the traps led to capture. Large (> 80-mm carapace length) lobsters (Homarus americanus) left before entering the traps in 92% of 428 observed approaches, and were able to escape back out the entrance in 76% of the cases where they actually fed at the bait. Traps baited with thawed mackeral (Scomber scombrus) elicited more approaches and captures than did traps containing salted mackeral. Unbaited traps were virtually ignored, indicating they were not attractive as shelter. Lobsters were apparently drawn out of their shelters by the scent of bait, since individuals which lived immediately downstream from the rotating trap positions approached much more frequently than others. However, overall rates of approach and capture varied greatly between lobsters, suggesting that individuals have different motivational levels. These differences could not be explained on the basis of sex or size. Forty percent of the large lobsters were never caught, despite being offered baited traps in 20 separate trials. Longer-term studies are needed to determine whether such individuals will enter traps at different times of year or whether they remain permanently untrapable.
Karyotype of Zea luxurians and Z. mays subsp. mays using FISH/DAPI, and analysis of meiotic behavior of hybridsIn memoriam of Dr. Carlos A. Naranjo.
Authors: González Graciela E. , Poggio Lidia
Published: January 2011

The karyotypes of Zea luxurians and a race of maize from northwestern Argentina are described and compared using 4′,6-diamidino-2-phenylindole (DAPI) banding and fluorescent in situ hybridization (FISH) to localize the 180 bp knobs. The meiotic behavior of the F1 artificial hybrids Z. luxurians × maize is also analyzed to determine the genomic relationships between both species. Neocentromere activity at knobs in the meiosis of the hybrids is particularly discussed. The meiotic behavior and the high pollen sterility of the hybrid revealed genetical and (or) chromosomal divergences, leading to postzygotic reproductive isolation among their parents. Here, we propose that maize shows lower genomic affinity to Z. luxurians than to other species of the genus with 2n = 20.
Massive alterations of the methylation patterns around DNA transposons in the first four generations of a newly formed wheat allohexaploid
Authors: Yaakov Beery , Kashkush Khalil
Published: January 2011

Rapid and reproducible genomic changes can be induced during the early stages of the life of nascent allopolyploid species. In a previous study, it was shown that following allopolyploidization, cytosine methylation changes can affect up to 11% of the wheat genome. However, the methylation patterns around transposable elements (TEs) were never studied in detail. We used transposon methylation display (TMD) to assess the methylation patterns of CCGG sites flanking three TE families (Balduin, Apollo, and Thalos) in the first four generations of a newly formed wheat allohexaploid. In addition, transposon display (TD), using a methylation-insensitive restriction enzyme, was applied to search for genomic rearrangements at the TE insertion sites. We observed that up to 54% of CCGG sites flanking the three TE families showed changes in methylation patterns in the first four generations of a newly formed wheat allohexaploid, where hypermethylation was predominant. Over 70% of the changes in TMD patterns occurred in the first two generations of the newly formed allohexaploid. Furthermore, analysis of 555 TE insertion sites by TD and 18 cases by site-specific PCR revealed a full additive pattern in the allohexaploid, an indication for lack of massive rearrangements. These data indicate that following allopolyplodization, DNA-TE insertion sites can undergo a significantly high level of methylation changes compared with methylation changes of other genomic sequences.