bluuebunny/crossref_metadata_2025 huggingface dataset:
Convective Cooling Optimization of a Blade for a Supercritical Steam Turbine
Authors: Nowak Grzegorz , Wro´blewski Włodzimierz , Nowak Iwona
Published: May 2012

This paper discusses the problem of blade cooling system optimization connected with Conjugate Heat Transfer (CHT) analysis for reliable thermal field prediction within a steam cooled component. Since the full CHT solution, which involves the main flow, blade material and the coolant flow domains is computationally expensive from the point of view of optimization process, it was decided to reduce the problem by fixing the boundary conditions at the blade surface and solving the task for the interior only (both solid material and coolant). Such assumption, on one hand, makes the problem computationally feasible, and on the other, provides more reliable thermal field prediction than it used to be with the empirical relationships. The analysis involves shape optimization of internal cooling passages within an airfoil. The cooling passages are modeled with a set of four Bezier splines joined together to compose a closed contour. Each passage is fed with cooling steam of constant parameters at the inlet. In the present study the airfoil profile is taken as aerodynamically optimal. The search problem is solved with evolutionary algorithm and the final configuration is to be found among the Pareto optimal cooling candidates.
Health Monitoring in an Industrial Gas Turbine Application by Using Model Based Diagnosis Techniques
Authors: Larsson Emil , A˚slund Jan , Frisk Erik , Eriksson Lars
Published: May 2012

Monitoring of an industrial gas turbine is important since it gives valuable information for the customer about maintenance, performance and process health. The objective of the paper is to develop a monitoring system for an industrial gas turbine application with a model based diagnosis approach. A constant gain extended Kalman observer is developed. The observer compensates for different ambient conditions such as pressure, temperature and relative humidity, due to the amount of water in the atmosphere. The developed observer, extended with seven health parameters, is automatically constructed from the diagnosis model. These health parameters shall capture deviations in some of the gas path performance parameters such as efficiency, mass flow, turbine inlet area and head loss. The constructed observer is evaluated through a simulation study where the ambient conditions are changed. The considered observer capture the change in different ambient conditions nearly perfect. An observer that does not compensate for different ambient conditions gives an error for about 1–2% for the considered health parameters for the given test case. The constructed observer is also evaluated on measurement data from a mechanical drive site. A degradation in efficiency and mass flow for the compressor due to fouling can be seen in the estimations. After the compressor wash is performed, the degradations for the compressor are partially restored by about 2% which can be seen in the considered health parameters.
Assessment of Various Turbulence Models in a High Pressure Ratio Centrifugal Compressor With an Object Oriented CFD Code
Authors: Mangani Luca , Casartelli Ernesto , Mauri Sebastiano
Published: May 2012

The flow field in a high pressure ratio centrifugal compressor with vaneless diffuser has been investigated numerically. Main goal is to assess the influence of various turbulence models suitable for internal flows with adverse pressure gradient. The numerical analysis is performed with a 3D RANS in-house modified solver based on an object-oriented open-source library. According to previous studies from varying authors, the turbulence model is believed to be the key parameter for the discrepancy between experimental and numerical results, especially at high pressure ratios and high mass-flow. Particular care has been taken at the wall, where a detailed integration of the boundary layer has been applied. The results presents different comparisons between the models and experimental data showing the influence of using advanced turbulence models. This is done in order to capture the boundary layer behavior, especially in large adverse pressure gradient single stage machinery.
Effects of Target Size on Foreign Object Damage in Gas-Turbine Grade Silicon Nitrides by Steel Ball Projectiles
Authors: Choi Sung R. , Ra´cz Zsolt
Published: May 2012

Foreign object damage (FOD) phenomena of two gas-turbine grade silicon nitrides (AS800 and SN282) were assessed at ambient temperature applying impact velocities from 20 to 300 m/s using 1.59-mm diameter hardened steel ball projectiles. Targets in a flexural configuration with two different sizes (thicknesses) of 1 and 2 mm were ballistic-impacted under a fully supported condition. The severity of impact damage, as well as the degree of post-impact strength degradation, increased with increasing impact velocity, increased with decreasing target size, and was greater in SN282 than in AS800 silicon nitride. The critical impact velocity where targets fractured catastrophically decreased with decreasing target size and was lower in SN282 than in AS800. Overall, FOD by steel projectiles was significantly less than that by silicon-nitride ceramic counterparts, due to much decreased Hertzian contact stresses. A correlation of backside cracking velocity versus target size was made based on a simplified elastic foundation analysis.
Passive Control of Noise and Instability in a Swirl-Stabilized Combustor With the Use of High-Strength Porous Insert
Authors: Sequera Daniel , Agrawal Ajay K.
Published: May 2012

Swirl-stabilized combustion and porous inert medium (PIM) combustion are two methods that have been used extensively, although independently, for flame stabilization. In this study, the two concepts are combined so that the porous insert serves as a passive device to mitigate combustion noise and instabilities. A properly shaped PIM is placed within the combustor to directly influence the turbulent flow field and vortical and/or shear layer structures associated with the outer recirculation zone and inner recirculation zone. After presenting the concept, the paper provides a conceptual understanding of the changes in the mean flow field caused by the PIM. Combustion experiments were conducted at atmospheric pressure using HfC/SiC coated open-cell foam structures of different pore sizes and shapes. Measurements of sound pressure level (SPL) and CO and NOx emissions were taken for different equivalence ratios and reactant flow rates. Combustion mode and PIM geometry to decrease the SPL are identified. Results show that the porous insert can reduce combustion noise without adversely affecting NOx and CO emissions. Experiments show that the proposed concept can also mitigate combustion instabilities encountered at high reactant flow rate.
Aerothermal Investigations on Mixing Flow Field of Film Cooling With Swirling Coolant Flow
Authors: Takeishi K. , Komiyama M. , Oda Y. , Egawa Y. , Kitamura T.
Published: May 2012

This paper describes the experimental results of a new film cooling method blowing through circular and shaped film cooling holes with swirling coolant flow. The experiments have been conducted by using a scale-up model of a film cooling hole installed on the bottom surface of a low-speed wind tunnel. Swirling motion of film coolant was induced inside a hexagonal plenum by two slant impingement jets, which are inclined at α degree toward the vertical direction and installed in a staggered position. The two impingement jets generate swirling flows inside the plenum, and this swirling flow enters into a film cooling hole keeping the angular momentum until the exit of the film cooling hole. The slant angle of the impingement jets was changed as α = 0°, 10°, 20°, 30° in their wind tunnel tests. The film cooling effectiveness on the flat wall was measured by using pressure sensitive paint (PSP) technique. In addition, the spatial distribution of non-dimensional concentration (or temperature) and flow field were measured by laser induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. In case of the circular film cooling hole, the coolant jet penetration into mainstream is suppressed by swirling motion of the coolant. As a result, though the coolant jet is deflected in the pitch direction, the film cooling effectiveness distribution on the wall keeps higher value behind the cooling hole over a long range. Additionally, kidney vortex structure disappeared. For the shaped cooling hole, the coolant jet spreads wider in spanwise direction at the downstream. Thus, the pitch averaged film cooling effectiveness at the downstream was 50% higher than that of the non-swirling case.
Optimization of Power Train Involving Gas Turbine Driven Compressors and Aerial Coolers
Authors: Botros K. K. , Golshan H. , Hawryluk A. , Sloof B.
Published: May 2012

Multi-objective optimizations were conducted for a compressor station comprising two dissimilar compressor units driven by two dissimilar gas turbines, two coolers of different size, and two parallel pipeline sections to the next station. Genetic algorithms were used in this optimization along with models describing the performance characteristics of gas turbines, compressors, aerial coolers, and downstream pipeline section. Essential in these models is the heat transfer between the gas and soil as it affects the pressure drop along the pipeline, and hence relates back to the coolers and compressor flow/pressure settings. Further investigative techniques were developed to also minimize NOx and CO2e emissions along with total energy consumption, i.e. fuel (used in the driver gas turbines) and electrical energy (used in the electrical fans of the aerial coolers). Two optimization scenarios were conducted: 1) Two-objective optimization of total energy consumption and NOx emission, and 2) Two-objective optimization of total energy consumption and CO2e emission. The results showed that savings in the energy consumption in the order of 5–6% is achievable with slight adjustment to unit load sharing and coolers by-pass/fan speed selections. It appears that most of the savings (around 70–75%) are derived from optimizing the load sharing between the two parallel compressors, while the balance of the savings is realized from optimizing the aerial coolers settings. In order to optimize operation for minimum NOx emission as well, a shift towards employing more of the aerial coolers is required. Preliminary cost analysis was conducted for valuation of balancing between energy consumption vs. emission loading in terms of both NOx and CO2e.
Aluminizing Turbine Parts: Processes and Coatings
Authors: Thoma Martin , Scrivani Andrea , Giolli Carlo , Giorgetti Andrea
Published: May 2012

Hot section gas turbine parts need protection against oxidation and hot corrosion. The essential element is Al to build the protective Al2O3. Al can be applied on the gas path surfaces by overlay techniques or by diffusion of Al into the base material — the “aluminizing”. Aluminizing can be done by slurry, pack cementation, out of pack, or by “pure” CVD. Additional elements can be added to the aluminide. The different techniques are discussed under the aspects of advantage/disadvantage, limits and possible coating structures.
A Method to Obtain Planar Mixture Fraction Statistics in Turbulent Flows Seeded With Tracer Particles
Authors: Pernpeintner M. , Lauer M. , Hirsch C. , Sattelmayer T.
Published: May 2012

We present a new method to obtain the mixture fraction probability density functions (PDF) of turbulent mixing in planar sections of a flow field which is seeded with PIV tracer particles. We derive a model how the observed scattered light obtained locally in a laser light sheet results from the local mixture fraction PDF and the particle density PDF. From this model we develop an analytical as well as a numerical inversion procedure that allows the deconvolution of the mixture fraction PDF from the light intensity PDF using the measured seeding PDF. We explain the experimental procedure necessary to apply the new technique on the example of a turbulent free jet. The results of both the analytical and the numerical method are compared and the method is then validated against the literature data. Since the method seems applicable whenever PIV measurements can be made it bears high potential for combustor development as it allows to obtain mixing statistics using basically the same measurement hardware.
Study of the Flow Over Wind Turbine Blade
Authors: Amano R. S. , Malloy Ryan J.
Published: May 2012

This paper presents the comparison of the performance between two different designs of wind turbine blades; one is a straight and the other with a backward swept blade. The straight edge blade was constructed so that it is optimal on coming wind and rotation speeds with 7m/s and 20rpm. The blade has a length of 20m and uses a constant airfoil cross section NACA 4412. The swept edge blade has the same characteristics as the straight edge except for the trajectory of the edge. Each cross section has the same dimensions and has at the same distance from the hub as its corresponding section in the straight edge blade. To test this new design the performance of both blades were measured using CFD at a wind speeds ranging 0 to 20m/s. Comparisons were made for power generation and acoustic noise for both designs of the blades.
Shot Peening Effect on Low Cycle Fatigue Properties of Ti-6Al-4V and Inconel 718
Authors: Nakamura Hiroshi , Takanashi Masahiro , Itabashi Yu , Kuroki Hiroshi , Ueda Yusuke
Published: May 2012

This study investigates the shot peening effect on low cycle fatigue properties of two turbo engine materials, Ti-6Al-4V and Inconel 718, in view of the residual stress relaxation by the cyclic load and the thermal relaxation. Strain controlled fatigue tests for Ti-6Al-4V were carried out at room temperature. The fatigue tests for Inconel 718 were conducted at room temperature and 620C. An X-ray diffraction method was used to measure the residual stresses induced by shot peening. The compressive residual stress of Ti-6Al-4V specimen had retained about 60% after half the number of cycles to failure. It is confirmed that shot peening enhances strain range capability of Ti-6Al-4V at the life between 104 and 105 cycles region about 1.5 times higher than that of non-peened specimen. This result is attributed to the retained compressive layer even after applied cyclic loading. Shot peening enhanced the strain range capability of the Inconel 718 specimen at room temperature, by a factor of 1.3 compared to polished specimen at the life of 104 cycles region. The residual stress near the surface has been relaxed rapidly at turbine engine temperature, however, the residual stresses in the deep subsurface have been retained. The peened specimen tested at 620C tended to be slightly higher strain range than those of polished specimen at the life of 105 cycles.
Modeling Foreign Object Damage to CVI MI SiC/iBN/SiC and Oxide/Oxide Ceramic Composite Components in Gas Turbine Engines at Ambient and Elevated Temperatures
Authors: Abdi Frank , Yun HeeMann , Godines Cody , Morscher Gregory
Published: May 2012

The inherent toughness of ceramic matrix composites (CMCs) in advanced gas-turbine engines must be predictable under impact from small foreign objects to lower the amount of full scale testing needed to produce robust designs. Fiber/matrix/architecture properties of the composites, and a damage evolution based progressive failure code that can be used for a full range of composite architectures (GENOA) coupled with an explicit FEM impact code (LS-DYNA) were used to simulate impact and residual 4pt flexural strength of the ceramic engine components. This approach uses physics-based mechanics coupled at the micro and macro scale boundaries. The benefit of this technique is that the root cause of damage advancement at the micromechanical level could be understood and simulations could be performed to assess better damage tolerance structures. Steel projectiles with a diameter of 1.59 mm were used to impact the composites at speeds from 100–400 m/s (Mach 0.3–1.2) and the results shown to compare to prior test data for 2-D 5H Sylramic iBN CVI MI SiC at 25°C and 1316°C and for 2-D 8H N720/AS ceramic composites at 25°C. Simulations also gave insight to the micromechanical damage progression and were comparable with test data.
Flow Distribution and Heat Transfer Coefficients Inside Gas Holes Discharging Into an Orthogonal Crossflow
Authors: Acharya S. , Eshtiaghi A. , Schilp R.
Published: May 2012

Fluid flow and heat transfer coefficient associated with flow inside short holes (L/D = 1) discharging orthogonally into a crossflow was investigated experimentally and numerically for Re ranging from 0.5×105 to 2×105, and blowing ratio ranging from 1.3 to 3.2. The basic configuration studied consists of a feed tube with five orthogonally located gas holes. Four different hole configurations were studied. The transient heat transfer study employs an IR-camera to determine the local heat transfer coefficient inside each hole. Velocity measurements and numerical flow simulation were used to better understand the measured heat transfer distribution inside the hole. The Nusselt number distribution along the hole surface exhibits significant circumferential non-uniformity associated with impingement and separation, with localized high heat transfer regions caused by flow impingement. The heat transfer coefficient was observed to be a strong function of the Reynolds number, but a weak function of the blowing ratio.
Optimal Application of Riblets on Compressor Blades and Their Contamination Behavior
Authors: Lietmeyer Christoph , Oehlert Karsten , Seume Joerg R.
Published: May 2012

During the last decades, riblets have shown a potential for viscous drag reduction in turbulent boundary layers. Several investigations and measurements of skin-friction in the boundary layer over flat plates and on turbomachinery type blades with ideal riblet geometry have been reported in the literature. The question where riblets must be applied on the surface of a compressor blade is still not sufficiently answered. In a first step, the profile loss reduction by ideal triangular riblets with a trapezoidal groove and a constant geometry along the surface on the suction and pressure side of a compressor blade is investigated. The results show a higher potential on the profile loss reduction by riblets on the suction side. In a second step, the effect of laser-structured ribs on the laminar separation bubble and the influence of these structures on the laminar boundary layer near the leading edge are investigated. After clarifying the best choices where riblets should be applied on the blade surface, a strategy for locally adapted riblets is presented. The suction side of a compressor blade is laser-structured with a segmented riblet-like structure with a constant geometry in each segment. The measured profile loss reduction shows the increasing effect on the profile loss reduction of this locally adapted structure compared to a constant riblet-geometry along the surface. Furthermore, the particle deposition on a riblet-structured compressor blade is investigated and compared to the particle deposition on a smooth surface. Results show a primary particle deposition on the riblet tips followed by an agglomeration. The particle deposition on the smooth surface is stochastic.
Failure Investigation of 1st Stage Buckets From Frame 3002, 10 MW Gas Turbine Unit
Authors: Shejale Girish M. , Ross David
Published: May 2012

The 1st stage buckets in Frame 3002, 10 MW industrial gas turbine experienced premature failures. The buckets failed unexpectedly much earlier than the designed bucket life. Bucket material is Inconel 738, with platinum-aluminized coating on the surface. Failure investigation of the buckets was performed to know the root cause of the failure. The failure investigation primarily comprised of metallurgical investigation. The results of the metallurgical investigation were co-related with the unit operational history. This paper provides an overview of 1st stage buckets investigation. The metallurgical investigation performed concluded prime failure mechanism due to high carbon content of bucket material and improper heat treatment. The bucket coating was initially damaged during the first loading and fracture occurred due to grain boundary embrittlement in short span of service. The metallurgical tests performed included Visual inspection, Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of X-ray (EDS), Chemical analysis, Tensile test and Hardness survey. The test results, discussions and conclusions are presented in this paper.
Ion induced modification of size-selected MoO3 and WO3 clusters deposited on HOPG
Authors: Li Xiang , Wepasnick Kevin A. , Tang Xin , Wang Yi , Bowen Kit H. , Fairbrother D. Howard , Gantefoer Gerd
Published: May 2012

The effect of 4 keV Ar+ ions on size-selected (MoO3)n and (WO3)n clusters, where n = 30 ± 1, deposited on highly ordered pyrolytic graphite was studied by x-ray photoelectron spectroscopy and atomic force microscopy. During deposition, both metal oxide clusters collected preferentially at step edges at low coverages, with larger cluster aggregates nucleating on the terraces at higher coverages. Under the influence of 4 keV Ar+ ion bombardment, both clusters initially experienced oxygen loss and corresponding reduction of the transition metal before the remaining species were sputtered from the surface. However, MoO3 was only partially reduced to MoO2, while WO3 was fully reduced to metallic tungsten. As a consequence of these variations in ion induced chemistry, changes in the surface morphology of MoO3 and WO3 following prolonged Ar+ exposure differed significantly. For (MoO3)30±1, the size of the clusters decreased, due to removal of MoO2 fragments. In contrast, for (WO3)30±1, the formation of smaller sized clusters was also accompanied by the appearance of clusters that were much larger in size than the original “as deposited” clusters. The creation of these larger structures is ascribed to the mobility and coalescence of metallic tungsten species produced during the sputtering process. The contrast in the behavior of the molybdenum and tungsten oxide clusters illustrates the interplay that can exist between ion induced changes in speciation and morphology of deposited clusters.
Uncaging Akt
Authors: Humphrey Sean J. , James David E.
Published: May 2012

ATP and ADP regulate a conformational switch that determines the kinase activity of Akt.
Focus Issue: Series on Structural Biology
Authors: Wong Wei
Published: May 2012

Research and commentary highlight the use of structural analysis to understand signaling molecules and events.
Not Broken Until Repaired
Authors: Riddihough Guy
Published: May 2012

“Naked” chromosome ends are mistakenly targeted by six different DNA repair–related systems in the cell.
Blood Pressure Gauge
Authors: Ray L. Bryan
Published: May 2012

Imaging reveals single-channel openings of cation channels at the heart of endothelial cell–mediated blood pressure control.
Gene Expression by Remote Control
Authors: Kiberstis Paula A.
Published: May 2012

Gene expression in mice can be activated remotely and noninvasively by radio-wave heating of nanoparticles.
Metabolic Networking
Authors: Ray L. Bryan
Published: May 2012

A key design principle of bacterial metabolic networks is optimal performance, but not at the expense of adaptability.
Three Dimensions, Two Modes of Migration
Authors: Andrianantoandro Ernesto
Published: May 2012

Elastic properties of the extracellular matrix and nonpolarized signaling govern how cells migrate in three-dimensional environments.
Population Pharmacokinetics and Pharmacodynamics of Ofloxacin in South African Patients with Multidrug-Resistant Tuberculosis
Authors: Chigutsa Emmanuel , Meredith Sandra , Wiesner Lubbe , Padayatchi Nesri , Harding Joe , Moodley Prashini , Mac Kenzie William R. , Weiner Marc , McIlleron Helen , Kirkpatrick Carl M. J.
Published: May 2012

Despite the important role of fluoroquinolones and the predominant use of ofloxacin for treating multidrug-resistant tuberculosis in South Africa, there are limited data on ofloxacin pharmacokinetics in patients with multidrug-resistant tuberculosis, no ofloxacin pharmacokinetic data from South African patients, and no direct assessment of the relationship between ofloxacin pharmacokinetics and the MIC of ofloxacin of patient isolates. Our objectives are to describe ofloxacin pharmacokinetics in South African patients being treated for multidrug-resistant tuberculosis and assess the adequacy of ofloxacin drug exposure with respect to the probability of pharmacodynamic target attainment (area under the time curve/MIC ratio of at least 100). Sixty-five patients with multidrug-resistant tuberculosis were recruited from 2 hospitals in South Africa. We determined the ofloxacin MICs for the
Mycobacterium tuberculosis
isolates from baseline sputum specimens. Patients received daily doses of 800 mg ofloxacin, in addition to other antitubercular drugs. Patients underwent pharmacokinetic sampling at steady state. NONMEM was used for data analysis. The population pharmacokinetics of ofloxacin in this study has been adequately described. The probability of target attainment expectation in the study population was 0.45. Doubling the dose to 1,600 mg could increase this to only 0.77. The currently recommended ofloxacin dose appeared inadequate for the majority of this study population. Studies to assess the tolerability of higher doses are warranted. Alternatively, ofloxacin should be replaced with more potent fluoroquinolones.
Effect of Telaprevir on the Pharmacokinetics of Buprenorphine in Volunteers on Stable Buprenorphine/Naloxone Maintenance Therapy
Authors: Luo Xia , Trevejo Jose , van Heeswijk Rolf P. G. , Smith Frances , Garg Varun
Published: May 2012

This was an open-label, single-sequence trial in hepatitis C virus-negative volunteers on stable, individualized, buprenorphine maintenance therapy. Telaprevir at 750 mg every 8 h was coadministered with buprenorphine/naloxone (4:1 ratio as sublingual tablets) for 7 days with food. Pharmacokinetic profiles of buprenorphine, norbuprenorphine, and naloxone were measured over the 24-hour dosing interval on day −1 (buprenorphine/naloxone alone, reference) and day 7 of telaprevir coadministration (test). Geometric least-squares mean ratios and associated 90% confidence intervals of treatment ratios (test/reference) were calculated using log-transformed pharmacokinetic parameters. Opioid withdrawal symptoms were evaluated throughout the study (via questionnaires and pupillometry). Pharmacokinetic data were available for 14 and 13 volunteers on day −1 and day 7, respectively. The area under the concentration-time curve (AUC) for buprenorphine was unchanged and the maximum concentration of drug in serum (
C
max
) for buprenorphine,
C
max
and AUC for norbuprenorphine, and
C
max
naxolone were modestly decreased during coadministration with telaprevir. Geometric least-squares mean ratios (90% confidence intervals) for buprenorphine were 0.80 (0.69, 0.93) for the
C
max
and 0.96 (0.84, 1.10) for the AUC from 0 to 24 h (AUC
0–24
); for norbuprenorphine, values were 0.85 (0.66, 1.09) for
C
max
and 0.91 (0.71, 1.16) for AUC
0–24
; for naloxone, the
C
max
was 0.84 (0.62, 1.13). Coadministration of telaprevir did not increase withdrawal symptom frequency, and there were no serious adverse events reported during or after completion of telaprevir coadministration. Results suggest dose adjustment may not be necessary when telaprevir and buprenorphine/naloxone are coadministered.
Dual Roles of FmtA in Staphylococcus aureus Cell Wall Biosynthesis and Autolysis
Authors: Qamar Aneela , Golemi-Kotra Dasantila
Published: May 2012

The
fmtA
gene is a member of the
Staphylococcus aureus
core cell wall stimulon. The FmtA protein interacts with β-lactams through formation of covalent species. Here, we show that FmtA has weak
d
-Ala-
d
-Ala-carboxypeptidase activity and is capable of covalently incorporating C14-Gly into cell walls. The fluorescence microscopy study showed that the protein is localized to the cell division septum. Furthermore, we show that wall teichoic acids interact specifically with FmtA and mediate recruitment of FmtA to the
S. aureus
cell wall. Subjection of
S. aureus
to FmtA concentrations of 0.1 μM or less induces autolysis and biofilm production. This effect requires the presence of wall teichoic acids. At FmtA concentrations greater than 0.2 μM, autolysis and biofilm formation in
S. aureus
are repressed and growth is enhanced. Our findings indicate dual roles of FmtA in
S. aureus
growth, whereby at low concentrations, FmtA may modulate the activity of the major autolysin (AtlA) of
S. aureus
and, at high concentrations, may participate in synthesis of cell wall peptidoglycan. These two roles of FmtA may reflect dual functions of FmtA in the absence and presence of cell wall stress, respectively.
Caspofungin Etest Susceptibility Testing of Candida Species: Risk of Misclassification of Susceptible Isolates of C. glabrata and C. krusei when Adopting the Revised CLSI Caspofungin Breakpoints
Authors: Arendrup Maiken Cavling , Pfaller Michael A. ,   the Danish Fungaemia Study Group
Published: May 2012

The purpose of this study was to evaluate the performance of caspofungin Etest and the recently revised CLSI breakpoints. A total of 497 blood isolates, of which 496 were wild-type isolates, were included. A total of 65/496 susceptible isolates (13.1%) were misclassified as intermediate (I) or resistant (R). Such misclassifications were most commonly observed for
Candida krusei
(73.1%) and
Candida glabrata
(33.1%). The revised breakpoints cannot be safely adopted for these two species.
Effect of Clarithromycin in Inflammatory Markers of Patients with Ventilator-Associated Pneumonia and Sepsis Caused by Gram-Negative Bacteria: Results from a Randomized Clinical Study
Authors: Spyridaki Aikaterini , Raftogiannis Maria , Antonopoulou Anastasia , Tsaganos Thomas , Routsi Christina , Baziaka Fotini , Karagianni Vassiliki , Mouktaroudi Maria , Koutoukas Pantelis , Pelekanou Aimilia , Kotanidou Anastasia , Orfanos Stylianos E. , van der Meer Jos W. M. , Netea Mihai G. , Giamarellos-Bourboulis Evangelos J.
Published: May 2012

One recent, double-blind, randomized clinical trial with 200 patients showed that clarithromycin administered intravenously for 3 days in patients with ventilator-associated pneumonia (VAP) accelerated the resolution of pneumonia and decreased the risk of death from septic shock and multiple organ dysfunctions (MODS). The present study focused on the effect of clarithromycin on markers of inflammation in these patients. Blood was drawn immediately before the administration of the allocated treatment and on six consecutive days after the start of treatment. The concentrations of circulating markers were measured. Monocytes and neutrophils were isolated for immunophenotyping analysis and for cytokine stimulation. The ratio of serum interleukin-10 (IL-10) to serum tumor necrosis factor alpha (TNF-α) was decreased in the clarithromycin group compared with the results in the placebo group. Apoptosis of monocytes was significantly increased on day 4 in the clarithromycin group compared with the rate of apoptosis in the placebo group. On the same day, the expression of CD86 was increased and the ratio of soluble CD40 ligand (sCD40L) to CD86 in serum was unchanged. The release of TNF-α, IL-6, and soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) by circulating monocytes after stimulation was greater in the clarithromycin group than in the placebo group. The expression of TREM-1 on monocytes was also increased in the former group. These effects were pronounced in patients with septic shock and MODS. These results suggest that the administration of clarithromycin restored the balance between proinflammatory versus anti-inflammatory mediators in patients with sepsis; this was accompanied by more efficient antigen presentation and increased apoptosis. These effects render new perspectives for the immunotherapy of sepsis.
Interleukin-10 (IL-10) Polymorphisms Are Associated with IL-10 Production and Clinical Malaria in Young Children
Authors: Zhang Guicheng , Manaca Maria Nelia , McNamara-Smith Michelle , Mayor Alfredo , Nhabomba Augusto , Berthoud Tamara Katherine , Khoo Siew-Kim , Wiertsema Selma , Aguilar Ruth , Barbosa Arnoldo , Quintó Llorenç , Candelaria Pierre , Schultz En Nee , Hayden Catherine M. , Goldblatt Jack , Guinovart Caterina , Alonso Pedro L. , LeSouëf Peter N. , Dobaño Carlota
Published: May 2012

The role of interleukin-10 (IL-10) in malaria remains poorly characterized. The aims of this study were to investigate (i) whether genetic variants of the IL-10 gene influence IL-10 production and (ii) whether IL-10 production as well as the genotypes and haplotypes of the IL-10 gene in young children and their mothers are associated with the incidence of clinical malaria in young children. We genotyped three IL-10 single nucleotide polymorphisms in 240 children and their mothers from a longitudinal prospective cohort and assessed the IL-10 production by maternal peripheral blood mononuclear cells (PBMCs) and cord blood mononuclear cells (CBMCs). Clinical episodes of
Plasmodium falciparum
malaria in the children were documented until the second year of life. The polymorphism IL-10 A-1082G (GCC haplotype of three SNPs in IL-10) in children was associated with IL-10 production levels by CBMC cultured with
P. falciparum
-infected erythrocytes (
P
= 0.043), with the G allele linked to low IL-10 production capacity. The G allele in children was also significantly associated with a decreased risk for clinical malaria infection in their second year of life (
P
= 0.016). Furthermore, IL-10 levels measured in maternal PBMCs cultured with infected erythrocytes were associated with increased risk of malaria infection in young children (
P
< 0.001). In conclusion, IL-10 polymorphisms and IL-10 production capacity were associated with clinical malaria infections in young children. High IL-10 production capacity inherited from parents may diminish immunological protection against
P. falciparum
infection, thereby being a risk for increased malaria morbidity.
The Helicobacter pylori Autotransporter ImaA (HP0289) Modulates the Immune Response and Contributes to Host Colonization
Authors: Sause William E. , Castillo Andrea R. , Ottemann Karen M.
Published: May 2012

The human pathogen
Helicobacter pylori
employs a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced gene
HP0289
, which encodes an uncharacterized outer membrane protein. We first generated an isogenic
H. pylori
mutant that lacks
HP0289
and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-type
H. pylori
. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that the
HP0289
promoter is upregulated in the mouse stomach, and here we demonstrate that
HP0289
expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that the
HP0289
mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-type
H. pylori
. On the basis of this phenotype, we renamed HP0289 ImaA for
i
mmuno
m
odulatory
a
utotransporter protein. Our work has revealed that genes induced
in vivo
play an important role in
H. pylori
pathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allow
H. pylori
to fine tune the host immune response based on ImaA expression.
Genome Sequence of Herpes Simplex Virus 1 Strain KOS
Authors: Macdonald Stuart J. , Mostafa Heba H. , Morrison Lynda A. , Davido David J.
Published: May 2012

Herpes simplex virus type 1 (HSV-1) strain KOS has been extensively used in many studies to examine HSV-1 replication, gene expression, and pathogenesis. Notably, strain KOS is known to be less pathogenic than the first sequenced genome of HSV-1, strain 17. To understand the genotypic differences between KOS and other phenotypically distinct strains of HSV-1, we sequenced the viral genome of strain KOS. When comparing strain KOS to strain 17, there are at least 1,024 small nucleotide polymorphisms (SNPs) and 172 insertions/deletions (indels). The polymorphisms observed in the KOS genome will likely provide insights into the genes, their protein products, and the
cis
elements that regulate the biology of this HSV-1 strain.
Complete Genome Sequence of Two Novel Chinese Virulent Porcine Reproductive and Respiratory Syndrome Virus Variants
Authors: Zhou Zhi , Li Xiangdong , Liu Qi , Hu Dongmei , Yue Xiaojuan , Ni Jianqiang , Yu Xiuling , Zhai Xinyan , Galliher-Beckley Amy , Chen Nanhua , Shi Jishu , Tian Kegong
Published: May 2012

A highly pathogenic strain of porcine reproductive and respiratory syndrome virus (PRRSV), characterized by a discontinuous 30-amino-acid deletion in its Nsp2-coding region, has been emerging in China since 2006. Here, we report the complete genomic sequence of two novel Chinese virulent PRRSV variants with additional NSP2-gene deletions, which will help us understand the molecular and evolutionary characteristics of PRRSV in Asia.
Complete Genome Sequence of a Novel Picobirnavirus, Otarine Picobirnavirus, Discovered in California Sea Lions
Authors: Woo Patrick C. Y. , Lau Susanna K. P. , Bai Ru , Teng Jade L. L. , Lee Paul , Martelli Paolo , Hui Suk-Wai , Yuen Kwok-Yung
Published: May 2012

We discovered a novel otarine picobirnavirus in fecal samples of California sea lions. Its genome contains a large segment with two open reading frames (ORFs), ORF1 encoding a putative protein of 163 amino acids with unknown function and ORF2 encoding capsid protein, and a small segment with one ORF encoding RNA-dependent RNA polymerase.
Complete Genome Sequence of Bacillus cereus Bacteriophage PBC1
Authors: Kong Minsuk , Kim Minsik , Ryu Sangryeol
Published: May 2012

Bacillus cereus
is a ubiquitous, spore-forming bacterium associated with food poisoning cases. To develop an efficient biocontrol agent against
B. cereus
, we isolated lytic phage PBC1 and sequenced its genome. PBC1 showed a very low degree of homology to previously reported phages, implying that it is novel. Here we report the complete genome sequence of PBC1 and describe major findings from our analysis.
Combination use of Beck Depression Inventory and two-question case-finding instrument as a screening tool for depression in the workplace
Authors: Adachi Yasunori , Aleksic Branko , Nobata Ryoko , Suzuki Tatsuyo , Yoshida Keizo , Ono Yuichiro , Ozaki Norio
Published: May 2012

Objectives

The present study aimed to validate screening tools that could be used to identify depression among workers.

Design

Diagnostic test study.

Settings

Workers from three Japanese companies agreed to participate.

Participants

Recruitment for the group 1 occurred between January 2001 and February 2004, and 89 participants (81 men and 8 women with a mean age of 38.4±6.6 years) (98.8%) took part in the study. Recruitment for the group 2 occurred between July 2000 and February 2004, and 1500 participants (1408 men and 92 women with a mean age of 40.9±7.2 years) (94.2%) took part in the study. Demographic data are shown in supplementary table 1.

Interventions

Primary and secondary outcome measures: the Beck Depression Inventory (BDI) and a two-question case-finding instrument (TQI) were administered to 89 workers and Mini-International Neuropsychiatric Interview was conducted to verify the diagnosis of depression. A second group of 1500 workers completed the BDI and TQI to detect possible sample bias for the distribution of depression. Specificity, sensitivity and positive predictive value were calculated in order to obtain the optimal cut-off scores for BDI and TQI and receiver operating characteristic curves, and Youden Index were applied to further refine the optimal cut-off scores.

Results

When paired together, BDI score ≥10 and TQI score of 2 adequately identified workers who had major depressive disorder and those who had other psychiatric disorders that are frequently comorbid with major depressive disorder.

Conclusions

The combination of BDI score ≥10 and TQI score of 2 can adequately screen for current and potential cases of depression among workers. Furthermore, BDI and TQI offer the advantage of being relatively easy to administer to a large number of workers. Early detection of depression could improve treatment outcomes and decrease economic burden.

Trail registration
Genomic organization and dynamics of repetitive DNA sequences in representatives of three Fagaceae genera
Authors: Alves Sofia , Ribeiro Teresa , Inácio Vera , Rocheta Margarida , Morais-Cecílio Leonor
Published: May 2012

Oaks, chestnuts, and beeches are economically important species of the Fagaceae. To understand the relationship between these members of this family, a deep knowledge of their genome composition and organization is needed. In this work, we have isolated and characterized several AFLP fragments obtained from Quercus rotundifolia Lam. through homology searches in available databases. Genomic polymorphisms involving some of these sequences were evaluated in two species of Quercus , one of Castanea , and one of Fagus with specific primers. Comparative FISH analysis with generated sequences was performed in interphase nuclei of the four species, and the co-immunolocalization of 5-methylcytosine was also studied. Some of the sequences isolated proved to be genus-specific, while others were present in all the genera. Retroelements, either gypsy-like of the Tat/Athila clade or copia-like, are well represented, and most are dispersed in euchromatic regions of these species with no DNA methylation associated, pointing to an interspersed arrangement of these retroelements with potential gene-rich regions. A particular gypsy-sequence is dispersed in oaks and chestnut nuclei, but its confinement to chromocenters in beech evidences genome restructuring events during evolution of Fagaceae. Several sequences generated in this study proved to be good tools to comparatively study Fagaceae genome organization.
SOLVING MASTER EQUATION FOR CALDEIRA–LEGGETT MODEL BY VIRTUE OF THE THERMO ENTANGLED STATE REPRESENTATION AND THE IWOP TECHNIQUE
Authors: CHEN QIAN-FAN , YE QIAN , LI ZHI-HUA , FAN HONG-YI
Published: May 2012

In the present work, the exact formal solution of the Caldeira–Leggett quantum master equation for the reduced density matrix of an oscillator is obtained by virtue of the thermo entangled state representation and the technique of integration within an ordered product (IWOP) of operators. Also, the solution for high temperature approximation is derived. When the initial state is a coherent state, it will evolve into a displaced-squeezed chaotic state (a mixed state) which shows that decoherence is involved in the Caldeira–Leggett equation due to the interactions between the system and environment.
ROBUSTNESS OF HETEROGENOUS NETWORKS WITH MITIGATION STRATEGY AGAINST CASCADING FAILURES
Authors: WANG JIAN-WEI
Published: May 2012

The network disaster induced by cascading failures has traumatized modern societies. How to protect these networks and improve their robustness against cascading failures has become the key issue. To this end, we construct a cascading model and propose an efficient mitigation strategy against cascading failures. In many real-world networks, there exist some heterogeneous nodes, for example the hosts and the routers in the Internet, and the users and the supply-grid stations in the power grid. In previous studies, however, less cascading models were constructed to describe such fact. Including two types of nodes in a network, we present a new cascading model. We introduce a new mitigation strategy with dynamically adjusting the load and demonstrate its efficiency on the Barabási–Albert (BA) network and the power grid as well as the Internet. We show that with small changes in dynamically adjusting the load the robustness of these networks can be improved dramatically. Our results are useful not only for protecting networks from the local perspective, but also for significantly improving the robustness of the existing infrastructure networks.
The synthesis and metal binding chemistry of carbahemiporphyrazines with an electron withdrawing substituent
Authors: Costa Roshinee , Engle James T. , Ziegler Christopher J.
Published: May 2012

Benziphthalocyanine (bzpc) and dicarbahemiporphyrazine (dchp) are phthalocyanine analogs where one and two of the isoindoline units have been replaced with benzene rings. In this report, we present dchp and bzpc analogs 1 and 2 where CF3 groups have been placed on the 5-position of the benzene rings. Compounds 1 and 2 have identical structural features as their unmodified parent macrocycles, but some differences are observed in their metal adducts. Complex 1Ag shows few differences with the analogous dchp complex, but compounds 1Cu and 2Co exhibit reductions in M – C bond lengths arising from the electron withdrawing nature of the CF3 unit.
Genomics of estradiol-3-sulfate action in the ovine fetal hypothalamus
Authors: Rabaglino Maria Belen , Richards Elaine , Denslow Nancy , Keller-Wood Maureen , Wood Charles E.
Published: May 2012

In fetal sheep during late gestation sulfoconjugated estrogens in plasma reach a concentration 40–100 times greater than unconjugated estrogens. The objective of the present study was to determine the genomics of estradiol-3-sulfate (E2S) action in the ovine fetal brain. The hypothesis was that E2S stimulates genes involved in the neuroendocrine pathways that direct or facilitate fetal development at the end of gestation. Four sets of chronically catheterized ovine twin fetuses were studied (gestational age: 120–127 days gestation) with one infused with E2S intracerebroventricularly (1 mg/day) and the other remaining untreated (control). After euthanasia, mRNA samples were extracted from fetal brains. Only hypothalamic samples were employed for this study given the important function of this brain region in the control of the hypothalamus-pituitary-adrenal axis. Microarray analysis was performed following the Agilent protocol for one-color 8 × 15 microarrays, designed for Ovis aries. A total of 363 known genes were significantly upregulated by the E2S treatment ( P < 0.05). Network and enrichment analyses were performed using the Cytoscape/Bingo software, and the results validated by quantitative real-time PCR. The main overrepresented biological processes resulting from this analysis were feeding behavior, hypoxia response, and transforming growth factor signaling. Notably, the genes involved in the feeding behavior (neuropeptide Y and agouti-related protein) were the most strongly induced by the E2S treatment. In conclusion, E2S may be an important component of the mechanism for activating orexigenic, hypoxia responsiveness and neuroprotective pathways in the lamb as it approaches postnatal life.