bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and Experimental Investigation of the Film Cooling Effectiveness and Temperature Fields Behind a Novel Trench Configuration at High Blowing Ratio
Authors: Kröss Bernhard , Pfitzner Michael
Published: August 2013

The present study is a numerical and an experimental investigation of film cooling from cylindrical holes embedded in a 0.75D deep transverse trench. Additionally, a new design with tetrahedral elements located upstream of the trench was examined. They interact with the approaching boundary layer and modify the flow field near the trench. Different heights of the tetrahedrons were considered. Results from all geometries were compared to those from a cylindrical hole. The experiments were performed in a heated closed loop wind tunnel with a coolant supply at cryogenic temperatures. The adiabatic film cooling effectiveness was obtained using infrared thermography. Temperatures within the flow field were measured using a cold-wire. The experiments were performed at four blowing ratios (1.0, 2.0, 3.0 and 4.0) and two density ratios (1.19 and 1.75). CFD simulations using FLUENT were carried out in order to investigate the developing flow field. The results show that the cooling effectiveness of the trench configuration increases with increasing blowing ratio. The coolant film remains attached to the surface even at the highest blowing ratio. In comparison to the original trench configuration the adiabatic effectiveness is enhanced by the tetrahedral elements due to reduced mixing of coolant and hot gas within the trench and improved lateral spreading of cooling air. The variation of the density ratio showed that the measurements can not be scaled with the blowing ratio alone without considering the density ratio.
Conjugate Heat Transfer Analysis for Gas Turbine Cooled Stator
Authors: Ho Kuo-San , Urwiller Christopher , Konan S. Murthy , Liu Jong S. , Aguilar Bruno
Published: August 2013

This paper explores the conjugate heat transfer (CHT) numerical simulation approach to calculate the metal temperature for the gas turbine cooled stator. ANSYS CFX12.1 code was selected to be the computational fluid dynamic (CFD) tool to perform the CHT simulation. The 2-equation RNG k-ε turbulence model with scalable modified wall function was employed. A full engine test with thermocouple measurement was performed and used to validate the CHT results.

Metal temperatures calculated with the CHT model were compared to engine test data. The results demonstrated good agreement between test data and airfoil metal temperatures and cooling flow temperatures using the CHT model. However, the CHT calculations in the outer end wall had a discrepancy compared to the measured temperatures, which was due to the fact that the CHT model assumed an adiabatic wall as a boundary condition.

This paper presents a process to calculate convection heat transfer coefficient (HTC) for cooling passages and airfoil surfaces using CHT results. This process is possible because local wall heat flux and fluid temperatures are known. This approach assists in calibrating an in-house conduction thermal model for steady state and transient thermal analyses.
Experimental Study on Effects of Internal Rib and Rear Bump on Film Effectiveness
Authors: Sakai Eiji , Takahashi Toshihiko , Agata Yukiko
Published: August 2013

This paper reports detailed measurement of film cooling effectiveness for a scaled up film-cooling hole with an expanded exit fed by a smooth and ribbed secondary flow channel, an arrangement typical of turbine blades. The experiments are carried out at blowing ratios ranging from 0.4 to 1.25, and ten different rib patterns including forward oriented ribs and inverse oriented ribs are evaluated. Further, to develop an efficient film-cooling technique, several kinds of bumps are installed downstream of the hole exits, and the effects of the bumps on film effectiveness are investigated. The bump structures tested here are semicircular, hemispherical, and cylindrical bumps. The results show that the rib orientation strongly affects film effectiveness. When the blowing ratio is comparatively low, the forward oriented ribs afford higher film effectiveness. On the other hand, when the blowing ratio is comparatively high, the inverse oriented ribs afford higher film effectiveness. The cylindrical bump provides a better spreading of the ejected secondary flow than the other bumps, leading to higher film effectiveness. To clarify how the bumps improve the film effectiveness, computational simulations are performed. The simulations indicate that a longitudinal vortex, formed at the trailing edge of the cylindrical bump improves the film effectiveness by generating downward velocity vectors.
Computational Extrapolation of Turbine Sealing Effectiveness From Test Rig to Engine Conditions
Authors: Teuber Roy , Wilson Mike , Li Yan Sheng , Lock Gary , Maltson John , Owen J. Michael
Published: August 2013

The commercial computational fluid dynamics code ANSYS CFX 12.1 has been employed to carry out Unsteady Reynolds Averaged Navier Stokes (URANS) computations to investigate the fluid mechanics of two different rim-seal geometries in a 3D model of a turbine stage. The mainstream annulus, seal and wheel-space geometries are based on an experimental test rig used at the University of Bath. The calculated peak-to-trough pressure difference in the annulus, which is the main driving mechanism for ingestion, is in good agreement with experimental measurements. There is also good agreement between the computed and measured swirl ratios in the wheel-space.

Computed values of concentration-based sealing effectiveness are obtained over a range of sealing flow rates for both an axial-clearance and a radial clearance rim-seal. Good agreement with gas concentration measurements is found for the axial-clearance seal over a certain range of sealing flow rates. Some under-prediction of the amount of ingestion for the radial-clearance seal is obtained.

The computed mainstream pressure coefficient increases progressively with mainstream Mach number in moving from quasi-incompressible experimental rig conditions to the compressible flow conditions encountered in engines. It is shown that the minimum sealing flow rate required to prevent ingestion increases as mainstream Mach number increases. A scaling method is proposed to allow sealing flow rates to prevent ingestion obtained from low Mach number experiments to be extrapolated to engine-representative conditions.
Numerical Analysis of Film-Cooling Performance and Optimization for a Novel Shaped Film-Cooling Hole
Authors: Lee Ki-Don , Kim Sun-Min , Kim Kwang-Yong
Published: August 2013

In the present work, a numerical study on a novel shaped film-cooling hole has been performed. The novel shaped hole is designed to enhance lateral spreading of coolant on the cooling surface. The film-cooling performance of the novel shaped hole is compared with the fan, laidback fan, and dumbbell shaped film-cooling holes at density ratio of 1.75 in the range of blowing ratio from 0.5 to 2.5. The optimization of the novel shaped hole has been carried out to increase film-cooling effectiveness with four design variables, i.e., lateral expansion of the diffuser, forward expansion angle of the hole, length to diameter ratio of the hole, and pitch to diameter ratio of the hole. To optimize the hole shape, the radial basis neural network model is constructed and sequential quadratic programming is used to find optimal point from the surrogate model. The novel shaped hole shows remarkably improved film-cooling performance in comparison with the other film-cooling holes. The novel shaped hole modified by the optimization gives enhanced performance in comparison with the reference geometry.
An Investigation Into Numerical Analysis Alternatives for Predicting Re-Ingestion in Turbine Disc Rim Cavities
Authors: Valencia Antonio Guijarro , Dixon Jeffrey A. , Da Soghe Riccardo , Facchini Bruno , Smith Peter E. J. , Muñoz Julien , Eastwood Daniel , Long Christopher A. , Coren Daniel D. , Atkins Nicholas R.
Published: August 2013

Reliable means of predicting ingestion in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper, analysis is to be presented that results from an extended research programme, MAGPI, sponsored by the EU and several leading gas turbine manufactures and universities. Extensive use is made of CFD modelling techniques to understand the aerodynamic behaviour of a turbine stator well cavity, focusing on the interaction of cooling air supply with the main annulus gas. The objective of the study has been to benchmark a number of CFD codes and numerical techniques covering RANS and URANS calculations with different turbulence models in order to assess the suitability of the standard settings used in the industry for calculating the mechanics of the flow travelling between cavities in a turbine through the main gas path.

The modelling methods employed have been compared making use of experimental data gathered from a dedicated two-stage turbine rig, running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The limitations of the numerical methods in calculating the interaction of the cooling flow egress and the main stream gas, and subsequent ingestion into downstream cavities in the engine (i.e. re-ingestion), have been exposed. This has been done without losing sight of the validation of the CFD for its use for predicting heat transfer, which was the main objective of the partners of the MAGPI Work-Package 1 consortium.
Multi-Dimensional Platform for Cooling Design of Air-Cooled Turbine Blades
Authors: Chi Zhongran , Wang Songtao , Ren Jing , Jiang Hongde
Published: August 2013

Progresses in conjugate heat transfer simulation method provide a new approach for turbine blade cooling design. The procedure of air-cooled blade design introduced in this paper consists of two levels, a schematic design using 1D flow network calculation method, and a detailed design based on CFX conjugate heat transfer simulation.

The program platform for the design method was developed, including an air-cooled blade design program, a 1D cooling structure flow network solver, and conjugate mesh generation tools for air-cooled blade.

The design platform contains parametric methods for blade profile, cooling channel, and various cooling structures. The key parametric algorithm named Element Design Method was invented and introduced, which brings about parametric design for complex cooling channel, and accelerates the calculation model generation during the schematic design and detailed design.

The flow network solver for schematic design consists of a pressure solving program, a temperature solving program, and a film cooling solving program. The pressure solving program uses linear method to solve the momentum equation, so higher stability of the flow network solver can be achieved. In detailed design, CFD pre-treatment using the commercial software is time-consuming. The mesh generation tools, combined with parametric design programs, can automatically create hexahedron/mixed mesh for turbine cascade and cooling structures with considerable speed and quality, which significantly reduces the difficulty of pre-treatment during detailed design.
Characterization of the Influence of Moderate Pressure Fluctuations on the Cooling Performance of Advanced Combustor Cooling Concepts in a Reacting Flow
Authors: Behrendt Thomas , Gerendás Miklós
Published: August 2013

Lean low emission combustors are prone to combustion instabilities. Therefore integrating damping devices into the cooling concept is a viable approach. Information on the impact of pressure fluctuations caused by combustion instabilities on the cooling performance of both acoustic-focused and cooling-optimized concepts is required to support the decision regarding the cooling and damping strategy. In this contribution the effect of pressure fluctuations on different double skin cooling concepts in a realistic environment is presented. Pressure oscillations reduce the cooling effectiveness especially at low cooling air pressure drops. Here the cooling effectiveness of a more cooling optimized sample is affected most by the pressure oscillations. The cooling effectiveness of samples with a low thermal conductivity is more affected by the pressure fluctuations. Due to the low pressure drop across the hot gas wall and the perpendicular holes damping focused cooling concepts are prone to film fluid flowing back into the cavity during the pressure maximum of the oscillation. Together with the results the experimental approach is described and emphasis is laid on the adaption and validation of the measuring technique.
On the Lifting Performance of Finger Seal With Pad Grooved
Authors: Zhang Hai , Zheng Qun , Yue Guoqiang , Deng Qingfeng
Published: August 2013

A finger seal model with grooving structure is proposed and investigated in this paper. By grooving on the bottom of finger pad, we can get an unequal axial clearance between the finger pad and shaft. Two way fluid-solid interactions are simulated for those different grooved models. The results indicated many positive effects. Firstly, an irregular clearance happened due to the solid deformation. Secondly, the seal flow fields changed because of grooved structure. Thirdly, the grooving structure is valid to improve the seal lift performance. Fourthly, the vortices in the groove have effects to improve seal performance etc. The grooving structure could be designed differently for the different application.
Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane
Authors: Nathan Marc L. , Dyson Thomas E. , Bogard David G. , Bradshaw Sean D.
Published: August 2013

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of CFD simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.
Experimental Investigation of Turbine Phantom Cooling on Suction Side With Combustor-Turbine Leakage Gap Flow and Endwall Film Cooling
Authors: Zhang Yang , Yuan Xin
Published: August 2013

The film cooling injection on Hp turbine component surface is strongly affected by the complex flow structure in the nozzle guide vane or rotor blade passages. The action of passage vortex near endwall surface could dominate the film cooling effectiveness distribution on the component surfaces. The film cooling injections from endwall and airfoil surface are mixed with the passage vortex. Considering a small part of the coolant injection from endwall will move towards the airfoil suction side and then cover some area, the interaction between the coolants injected from endwall and airfoil surface is worth investigating. Though the temperature of coolant injection from endwall increases after the mixing process in the main flow, the injections moving from endwall to airfoil suction side still have the potential of second order cooling. This part of the coolant is called “Phantom cooling flow” in the paper. A typical scale-up model of GE-E3 Hp turbine NGV is used in the experiment to investigate the cooling performance of injection from endwall. Instead of the endwall itself, the film cooling effectiveness is measured on the airfoil suction side. This paper is focused on the combustor-turbine interface gap leakage flow and the coolant from fan-shaped holes moving from endwall to airfoil suction side. The coolant flow is injected at a 30deg angle to the endwall surface both from a slot and four rows of fan-shaped holes. The film cooling holes on the endwall and the leakage flow are used simultaneously. The blowing ratio and incidence angle are selected to be the parameters in the paper. The experiment is completed with the blowing ratio changing from M = 0.7 to M = 1.3 and the incidence angle varying from −10deg to +10deg, with inlet Reynolds numbers of Re = 3.5×105 and an inlet Mach number of Ma = 0.1.
Numerical Investigations on the Steam Cooling Performance of the First Two Middle Pressure Turbine Stages for Ultra-Supercritical Steam Turbines
Authors: Huo Wenhao , Li Jun , Yan Xin , Feng Zhenping
Published: August 2013

This paper researches the steam cooling performance applied in ultra-supercritical steam turbines. The inlet main steam temperature of the middle pressure cylinder is the same or higher than that of the inlet main steam of the high pressure cylinder due to the reheated technology used in the ultra-supercritical steam turbines. The steam cooling design is used to decrease the thermal fatigue and high temperature creep of the rotor in high temperature operation environments for the ultra-supercritical steam turbines. The conjugation flow and heat transfer method was applied to investigate the cooling characteristics of the first two stages solid parts including the rotor blade, wheel disc and rotor blade root of the middle pressure cylinder. In addition, the influences of the cooling steam on aerodynamic performance parameters distribution of the first two stages were also analyzed by comparison of the through flow calculations without steam cooling. The results show that the steam cooling design can effectively cool the rotor system of the first stage, and the temperature of the solid part near the cooling hole decreases by up to 30K. The temperature of the steam flowing through the diaphragm seal of the second stage increases and is higher than that of the local main flow. Therefore, the temperature of the rotor system of the second stage is relative high. Furthermore, the cooling steam enters into the through flow passage and mixes with the main flow. This flow behavior leads to changes of the flow pattern and aerodynamic parameters distribution near the blade hub regions.
Ecological Consequences of Sea-Ice Decline
Authors: Post Eric , Bhatt Uma S. , Bitz Cecilia M. , Brodie Jedediah F. , Fulton Tara L. , Hebblewhite Mark , Kerby Jeffrey , Kutz Susan J. , Stirling Ian , Walker Donald A.
Published: August 2013

After a decade with nine of the lowest arctic sea-ice minima on record, including the historically low minimum in 2012, we synthesize recent developments in the study of ecological responses to sea-ice decline. Sea-ice loss emerges as an important driver of marine and terrestrial ecological dynamics, influencing productivity, species interactions, population mixing, gene flow, and pathogen and disease transmission. Major challenges in the near future include assigning clearer attribution to sea ice as a primary driver of such dynamics, especially in terrestrial systems, and addressing pressures arising from human use of arctic coastal and near-shore areas as sea ice diminishes.
Climate Change and the Past, Present, and Future of Biotic Interactions
Authors: Blois Jessica L. , Zarnetske Phoebe L. , Fitzpatrick Matthew C. , Finnegan Seth
Published: August 2013

Biotic interactions drive key ecological and evolutionary processes and mediate ecosystem responses to climate change. The direction, frequency, and intensity of biotic interactions can in turn be altered by climate change. Understanding the complex interplay between climate and biotic interactions is thus essential for fully anticipating how ecosystems will respond to the fast rates of current warming, which are unprecedented since the end of the last glacial period. We highlight episodes of climate change that have disrupted ecosystems and trophic interactions over time scales ranging from years to millennia by changing species’ relative abundances and geographic ranges, causing extinctions, and creating transient and novel communities dominated by generalist species and interactions. These patterns emerge repeatedly across disparate temporal and spatial scales, suggesting the possibility of similar underlying processes. Based on these findings, we identify knowledge gaps and fruitful areas for research that will further our understanding of the effects of climate change on ecosystems.
Functional Lysine Modification by an Intrinsically Reactive Primary Glycolytic Metabolite
Authors: Moellering Raymond E. , Cravatt Benjamin F.
Published: August 2013

Modification Without Enzymes

Control of metabolic enzymes and regulation of many other biological processes is mediated in large part by binding of small molecules to proteins or through enzymatically medimediated covalent posttranslational modification of proteins.
Moellering and Cravatt
(p.
549
) wondered whether another scenario might occur in which reactive intermediates in a metabolic pathway might specifically react with and modify particular amino acids in proteins to produce regulatory changes without the need for catalysis by another enzyme. A particularly reactive intermediate formed during glycolysis, 1,3-bisphosphoglycerate, could nonenzymatically modify specific lysines in proteins, providing a means by which accumulation of metabolic intermediates could provide regulatory feedback to balance or control flux through various pathways. Proteomic analysis showed that the 3-phosphoglyceryl-lysine formed when certain lysine residues interacted with 1,3-bisphosphoglycerate produced naturally in cells and was particularly common in proteins that function in glycolysis. Such modification decreased activity of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase.
The Evolution of Social Monogamy in Mammals
Authors: Lukas D. , Clutton-Brock T. H.
Published: July 2013

The Only Flame in Town

Unusual for mammals, humans are notably socially monogamous, with pair bonding sometimes lasting decades. Why?
Lukas and Clutton-Brock
(p.
526
; see the Perspective by

Kappeler

) examined data from over 2500 mammalian species across 26 orders containing 60 evolutionary transitions to monogamy. In every case, the ancestral condition was one where females were solitary and where male infanticide was unusual. Monogamy appears to arise not as a response to a need for paternal care, but largely as a mate-guarding strategy.
A Role for SIRT2-Dependent Histone H3K18 Deacetylation in Bacterial Infection
Authors: Eskandarian Haig A. , Impens Francis , Nahori Marie-Anne , Soubigou Guillaume , Coppée Jean-Yves , Cossart Pascale , Hamon Mélanie A.
Published: August 2013

Bacterial Subversion Tactics

Intracellular bacterial pathogens such asListeria monocytogenescan change host cell transcription programs to promote infection.Eskandarianet al.(1238858) found that during infection, theListeriaeffector protein InlB promoted the movement of a host protein deacetylase, SIRT2, from its normal location in the cytosol to the nucleus. In the nucleus, SIRT2 helped to repress a number of host cell genes by deacetylating one of their associated histones. In mice, reduced levels of SIRT2 impaired bacterial infection.
Climate Change and Infectious Diseases: From Evidence to a Predictive Framework
Authors: Altizer Sonia , Ostfeld Richard S. , Johnson Pieter T. J. , Kutz Susan , Harvell C. Drew
Published: August 2013

Scientists have long predicted large-scale responses of infectious diseases to climate change, giving rise to a polarizing debate, especially concerning human pathogens for which socioeconomic drivers and control measures can limit the detection of climate-mediated changes. Climate change has already increased the occurrence of diseases in some natural and agricultural systems, but in many cases, outcomes depend on the form of climate change and details of the host-pathogen system. In this review, we highlight research progress and gaps that have emerged during the past decade and develop a predictive framework that integrates knowledge from ecophysiology and community ecology with modeling approaches. Future work must continue to anticipate and monitor pathogen biodiversity and disease trends in natural ecosystems and identify opportunities to mitigate the impacts of climate-driven disease emergence.
Efficient Generation of H
2
by Splitting Water with an Isothermal Redox Cycle
Authors: Muhich Christopher L. , Evanko Brian W. , Weston Kayla C. , Lichty Paul , Liang Xinhua , Martinek Janna , Musgrave Charles B. , Weimer Alan W.
Published: August 2013

Isothermal Water Splitting

Solar concentrators can create extremely high temperatures that can drive chemical reactions, including the thermal splitting of water to provide hydrogen. A metal oxide catalyst is needed that is usually cycled between hotter conditions where it is reduced and cooler conditions where it is reoxidized by water. This cycling can limit catalyst lifetime, which can be costly.

Muhich
et al.

(p.
540
; see the Perspective by

Roeb and Sattler

) developed an approach that allowed the redox cycle to be driven isothermally, using pressure swings.
Detection of a Spinning Object Using Light’s Orbital Angular Momentum
Authors: Lavery Martin P. J. , Speirits Fiona C. , Barnett Stephen M. , Padgett Miles J.
Published: August 2013

Doppler Effect with a Twist

The Doppler shift is a familiar and well-understood effect in acoustics. Radar guns use the same effect to determine the speed of moving vehicles. Applied to a rotating object side-on, however, a linear Doppler effect would register no movement. Using twisted light, whereby photons are imprinted with a given amount of optical angular momentum,

Lavery
et al.

(p.
537
; see the Perspective by

Marrucci

) detected rotation with an analogous angular Doppler shift, which may be useful for remote sensing and observational astronomy.
A Lifetime Without Memory
Permanent Present Tense
The Unforgettable Life of the Amnesic Patient, H.M.

by Suzanne Corkin

Basic Books, New York, 2013. 400 pp. $28.99, C$32. ISBN 9780465031597. Allen Lane, London. £20. ISBN 9781846142710.
Authors: Zeliadt Nicholette
Published: August 2013

Corkin's biography of "H.M." draws on her decades of work with the man whose amnesia has taught us so much about memory.
Y Weigh In Again on Modern Humans
Authors: Cann Rebecca L.
Published: August 2013

Sampling of the human Y chromosome eliminates the curious disparity in ages of our last common male and female ancestors.

[Also see Reports by

Poznik
et al.

and

Francalacci
et al.

]
Humans Greening a Landscape
Authors: Pennisi Elizabeth
Published: August 2013

Models and experiments only go so far in assessing the effects of climate change. For a reality check, researchers turn to historical photos.
miR-29 Acts as a Decoy in Sarcomas to Protect the Tumor Suppressor A20 mRNA from Degradation by HuR
Authors: Balkhi Mumtaz Y. , Iwenofu O. Hans , Bakkar Nadine , Ladner Katherine J. , Chandler Dawn S. , Houghton Peter J. , London Cheryl A. , Kraybill William , Perrotti Danilo , Croce Carlo M. , Keller Charles , Guttridge Denis C.
Published: July 2013

Loss of the decoy function of miR-29 destabilizes A20 transcripts, contributing to oncogenic activation of the transcription factor NF-κB in sarcomas.
Molecular Epidemiology of Clostridium difficile Infection in a Major Chinese Hospital: an Underrecognized Problem in Asia?
Authors: Hawkey Peter M. , Marriott Clare , Liu Wen En , Jian Zi Juan , Gao Qian , Ling Thomas Kin Wah , Chow Viola , So Erica , Chan Raphael , Hardy Katie , Xu Li , Manzoor Susan
Published: August 2013

Clostridium difficile
infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of
C. difficile
, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for
C. difficile
retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom
C. difficile
was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of
C. difficile
were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified
C. difficile
as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital.
C. difficile
may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.
Subtyping Clinical Specimens of Influenza A Virus by Use of a Simple Method To Amplify RNA Targets
Authors: Wang Jingjing , Tai Warren , Angione Stephanie L. , John Amrita R. , Opal Steven M. , Artenstein Andrew W. , Tripathi Anubhav
Published: August 2013

This work presents the clinical application of a robust and unique approach for RNA amplification, called a simple method for amplifying RNA targets (SMART), for the detection and identification of subtypes of H1N1 pandemic, H1N1 seasonal, and H3N2 seasonal influenza virus. While all the existing amplification techniques rely on the diffusion of two molecules to complex RNA structures, the SMART achieves fast and efficient amplification via single-molecule diffusion. The SMART utilizes amplifiable single-stranded DNA (ssDNA) probes, which serve as reporter molecules for capturing specific viral RNA (vRNA) sequences and are subsequently separated on a microfluidic chip under zero-flow conditions. The probe amplification and detection are performed using an isothermal (41°C) amplification scheme via a modified version of nucleic acid sequence-based amplification (NASBA). In our study, 116 consecutive, deidentified, clinical nasopharyngeal swab samples were analyzed independently in a blinded fashion using the SMART, reverse transcription-PCR (RT-PCR), antigen (Ag) testing, and viral culture. The SMART was shown to have a limit of detection (LOD) of approximately 10
5
vRNA copies/ml, corresponding with a time-to-positivity (TTP) value of 70 min for real-time detection. The SMART correctly detected influenza virus in 98.3% of the samples with a subtyping accuracy of 95.7%. This work demonstrates that the SMART represents a highly accurate diagnostic platform for the detection and subtyping of influenza virus in clinical specimens and offers significant advantages over the current commercially available diagnostic tools.
PCR and Electrospray Ionization Mass Spectrometry for Detection of Persistent Enterococcus faecalis in Cerebrospinal Fluid following Treatment of Postoperative Ventriculitis
Authors: Farrell John J. , Tsung Andrew J. , Flier Lisa , Martinez Derek L. , Beam Sarah B. , Chen Clifford , Lowery Kristin S. , Sampath Rangarajan , Bonomo Robert A.
Published: August 2013

We describe the use of PCR and electrospray ionization followed by mass spectrometry (PCR/ESI-MS) to evaluate “culture-negative” cerebrospinal fluid (CSF) from a 67-year-old man who developed postoperative bacterial ventriculitis following a suboccipital craniotomy for resection of an ependymoma in the 4th ventricle. CSF samples were obtained on seven occasions, beginning in the operating room at the time of insertion of a right ventriculoperitoneal shunt (VPS) and continuing until his death, 6 weeks later. During the course of the illness, two initial CSF specimens taken before the initiation of antimicrobial treatment were notable for growth of
Enterococcus faecalis
. Once antimicrobial treatment was initiated, all CSF cultures were negative. PCR/ESI-MS detected genetic evidence of
E. faecalis
in all CSF samples, but the level of detection (LOD) decreased once antimicrobial treatment was initiated. When our patient returned with symptoms of meningitis 3 days after the completion of antibiotic treatment, CSF cultures remained negative, but PCR/ESI-MS again found genetic evidence for
E. faecalis
at levels comparable to the pretreatment levels seen initially. This unique case and these findings suggest that determination of CSF LOD by PCR/ESI-MS may be a very sensitive indicator of persistent infection in patients on antibiotic therapy for complex CNS infections and may have relevance for treatment duration and assessment of persistent or recurrent infection at the completion of therapy.
Cell-Based Screening Assay for Antiviral Compounds Targeting the Ability of Herpesvirus Posttranscriptional Regulatory Proteins To Stabilize Viral mRNAs
Authors: Verma Dinesh , Kim Eun A , Swaminathan Sankar
Published: August 2013

Each human herpesvirus expresses a multifunctional regulatory protein that is essential for lytic viral replication. A cell-based assay targeting the function of these proteins was developed based on the finding that Epstein-Barr virus (EBV) SM and Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 stabilize specific target mRNAs. Both proteins facilitate the accumulation of lytic transcripts by incompletely characterized posttranscriptional mechanisms. SM and ORF57 exhibit target gene specificity and enhance the accumulation of certain EBV and KSHV mRNAs that are poorly expressed in their absence. Conversely, SM- and ORF57-independent viral and cellular transcripts accumulate efficiently, and their expression does not respond to SM or ORF57. Fusion of an ORF57-responsive transcript to ORF57-independent transcripts demonstrated that ORF57 dependence is
cis
-dominant. EBV SM also enhanced the accumulation of such fused mRNA transcripts. These data suggest that the coding regions of specific viral transcripts confer instability even when fused to heterologous genes. The findings were used to develop a reporter assay that measures EBV SM function in rescuing the expression of poorly expressed transcripts by posttranscriptional mechanisms. The assay represents a method for the screening of small interfering RNAs (siRNAs) and compounds to investigate the mechanism of action of SM and its homologs and potentially to aid in the discovery of novel antiviral agents.
Preferential HIV Infection of CCR6
+
Th17 Cells Is Associated with Higher Levels of Virus Receptor Expression and Lack of CCR5 Ligands
Authors: Alvarez Yelina , Tuen Michael , Shen Guomiao , Nawaz Fatima , Arthos James , Wolff Martin J. , Poles Michael A. , Hioe Catarina E.
Published: August 2013

Th17 cells are enriched in the gut mucosa and play a critical role in maintenance of the mucosal barrier and host defense against extracellular bacteria and fungal infections. During chronic human immunodeficiency virus (HIV) infection, Th17 cells were more depleted compared to Th1 cells, even when the patients had low or undetectable viremia. To investigate the differential effects of HIV infection on Th17 and Th1 cells, a culture system was used in which CCR6
+
CD4
+
T cells were sorted from healthy human peripheral blood and activated in the presence of interleukin 1β (IL-1β) and IL-23 to drive expansion of Th17 cells while maintaining Th1 cells. HIV infection of these cultures had minimal effects on Th1 cells but caused depletion of Th17 cells. Th17 loss correlated with greater levels of virus-infected cells and cell death. In identifying cellular factors contributing to higher susceptibility of Th17 cells to HIV, we compared Th17-enriched CCR6
+
and Th17-depleted CCR6
−
CD4 T cell cultures and noted that Th17-enriched CCR6
+
cells expressed higher levels of α4β7 and bound HIV envelope in an α4β7-dependent manner. The cells also had greater expression of CD4 and CXCR4, but not CCR5, than CCR6
−
cells. Moreover, unlike Th1 cells, Th17 cells produced little CCR5 ligand, and transfection with one of the CCR5 ligands, MIP-1β (CCL4), increased their resistance against HIV. These results indicate that features unique to Th17 cells, including higher expression of HIV receptors and lack of autocrine CCR5 ligands, are associated with enhanced permissiveness of these cells to HIV.
Intestinal adenocarcinoma in an augmented ileocystoplasty
Authors: Lopes Filipe Alpoim , Rolim Nidia , Rodrigues Tiago , Canhoto Artur
Published: August 2013

We present a case of a 67-year-old patient with a history of augmentation ileocystoplasty 31 years ago following genitourinary tuberculosis. Radiological investigations performed due to asymptomatic microscopic haematuria revealed three contrast-enhancing polyps within the neobladder. The patient had enterocystoprostatectomy and histopathological examination of the neobladder revealed mucinous adenocarcinoma in all three polyps, together with a prostatic adenocarcinoma Gleason 7 (3+4). After adjuvant chemotherapy and 1 year of follow-up, he had no sign of clinical or radiological recurrence. Taking into consideration this rare case, we discuss the development of malignant tumours after the incorporation of intestinal segments in a urinary tract reconstruction, showing what relationship exists between secondary neoplastic growth, the primary disease and the type of urinary diversion utilised.
Successful treatment of disseminated mucormycosis in a neutropenic patient with T-cell acute lymphoblastic leukaemia
Authors: Guymer Chelsea , Khurana Sanjeev , Suppiah Ram , Hennessey Iain , Cooper Celia
Published: August 2013

Mucormycosis is a rare angioinvasive fungal infection, more commonly seen in immunosuppressed patients, with reported mortality rates of 95% in disseminated disease. We present a case report of a patient with T-cell acute lymphoblastic leukaemia who developed disseminated infection with mucormycosis (involving the pancreas, left occipital lobe, right lower lobe of lung, appendix and right kidney) after having completed induction and consolidation chemotherapy. Growth ofLichtheimia corymbiferawas initially isolated following a right pleural tap with fungal elements identified repeatedly on subsequent pathology specimens. Following radical surgical debridement and concurrent treatment with combination antifungal therapy, the patient survived. This case demonstrates that aggressive multisite surgical de-bulking of disseminated fungal foci, in conjunction with combination antifungal therapy and reversal of immunosuppression, can result in survival despite the grave prognosis associated with disseminated mucormycosis.
T-condylar fractures of the distal humerus in children: report on three cases
Authors: Mok Churk Yan Jason , Lui Tun Hing
Published: August 2013

T-condylar fractures of the distal humerus are very rare in children. Because of their rarity, there is a lack of evidence in the literature on the best method to treat such fractures. We report the cases of three paediatric patients with T-condylar fracture of the distal humerus. A high degree of attention is needed in order not to miss the presence of intra-articular fracture, especially in the case of a low supracondylar fracture and in those with a history of high-energy trauma. Anatomic intra-articular fracture reduction is the key to success in managing this rare injury.
Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome secondary to antituberculosis drugs and associated with human herpes virus-7 (HHV-7)
Authors: Draz Nehal , Datta Sumona , Webster Daniel P , Cropley Ian
Published: August 2013

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a serious reaction to drugs with a clinical presentation of rash, fever, lymph node enlargement and internal organ involvement. Reports have described the reactivation of human herpes virus 6 (HHV-6) and other HHVs in association with this syndrome. We report a 41-year-old woman who developed a rash, fever, liver dysfunction, eosinophilia and atypical monocytosis 21 days after initiation of the quadruple therapy for tuberculous cervical lymphadnitis. HHV-7 DNA was detected in blood by PCR suggesting infection with or more likely reactivation of HHV-7 as a contributing factor or consequence of this serious adverse drug reaction.
Follow-up of the air pollution and the human male-to-female ratio analysis in São Paulo, Brazil: a times series study
Authors: Miraglia Simone Georges El Khouri , Veras Mariana Matera , Amato-Lourenço Luis Fernando , Rodrigues-Silva Fernando , Saldiva Paulo Hilário Nascimento
Published: July 2013

Objectives

In order to assess if ambient air pollution in urban areas could be related to alterations in male/female ratio this study objectives to evaluate changes in ambient particulate matter (PM10) concentrations after implementation of pollution control programmes in São Paulo city and the secondary sex ratio (SRR).

Design and methods

A time series study was conducted. São Paulo’s districts were stratified according to the PM10concentrations levels and were used as a marker of overall air pollution. The male ratio was chosen to represent the secondary sex ratio (SSR=total male birth/total births). The SSR data from each area was analysed according to the time variation and PM10concentration areas using descriptive statistics. The strength association between annual average of PM10concentration and SSR was performed through exponential regression, and it was adopted as a statistical significance level of p<0.05.

Results

The exponential regression showed a negative and significant association between PM10and SSR. SSR varied from 51.4% to 50.7% in São Paulo in the analysed period (2000–2007). Considering the PM10average concentration in São Paulo city of 44.72 μg/m3in the study period, the SSR decline reached almost 4.37%, equivalent to 30 934 less male births.

Conclusions

Ambient levels of PM10are negatively associated with changes in the SSR. Therefore, we can speculate that higher levels of particulate pollution could be related to increased rates of female births.
Use of health services following self-harm in urban versus suburban and rural areas: a national cross-sectional study
Authors: Fadum Elin Anita , Stanley Barbara , Rossow Ingeborg , Mork Erlend , Törmoen Anita J , Mehlum Lars
Published: July 2013

Objectives

This study examines whether there is a difference between urban versus suburban and rural adolescents in their use of health services following two types of self-harm distinguished as self-harm with or without suicide intent.

Setting

A nationwide cross-sectional school survey of 11 406 Norwegian adolescents aged 13–19 years in 73 Norwegian junior and senior high schools.

Participants

Adolescents who reported self-harm and provided valid responses to a follow-up question about having received subsequent help or treatment (n=959) were included in the study. Adolescents were divided into urban versus suburban and rural depending on: (1) the location of municipalities where they attended school and (2) the place of residence. Associations between urban versus suburban and rural areas and the use of health services following self-harm were assessed in those who self-harmed with and without suicide intent.

Primary outcome measure

Use of health services following self-harm.

Results

1 in 4 adolescents reported using health services following self-harm. Adolescents reporting self-harm with suicide intent were more likely to use health services than those who self-harmed without suicide intent. Following self-harm without suicide intent, adolescents in urban areas were four times more likely to use health services than adolescents in suburban and rural areas. There was no statistically significant area difference in the use of health services following self-harm with suicide intent.

Conclusions

This study found a geographical variation in the use of health services following self-harm without suicide intent, but not following self-harm with suicide intent. Differences in perception of self-harm and help-seeking behaviour between areas and different accessibility to services are suggested as possible explanations. There is a need to better understand how the interplay between individual characteristics and accessibility to services influences adolescents’ use of health services following self-harm. We suggest that multilevel models are a valuable approach to achieve this goal.
Issues for palliative medicine doctors surrounding the withdrawal of non-invasive ventilation at the request of a patient with motor neurone disease: a scoping study
Authors: Faull Christina , Rowe Haynes Cassy , Oliver David
Published: July 2013

Background

Non-invasive ventilation (NIV) is beneficial for respiratory failure in motor neurone disease (MND) but some patients may wish to stop the intervention. Guidance from the National Institute for Health and Care Excellence recommends that research is needed on NIV withdrawal. There is little in the literature focusing on the issues doctors face when withdrawing NIV in this group.

Aim

To identify issues and challenges that palliative medicine doctors encounter in relation to the withdrawal of NIV in MND patients.

Method

An electronic questionnaire was sent to members of the Association of Palliative Medicine of Great Britain and Ireland. Participants rated how practically, emotionally and ethically challenging they found the process of NIV withdrawal.

Results

76 doctors responding had been directly involved in withdrawal of NIV at the request of a patient with MND. A high percentage rated the practical, ethical and emotional challenges as 7 or more on a 0–10 scale. Thematic analysis of the free text revealed some common difficulties. Lack of guidance on practical aspects of withdrawal, poor advance care planning and the need to support all involved to prevent conflict were recurrent themes. Statements relating to the emotional burden were diverse but suggest many palliative care doctors feel significant personal impact.

Conclusions

The withdrawal of NIV in patients with MND appears to pose considerable challenges to palliative medicine doctors; emotionally, practically and to a lesser extent ethically. Development of guidelines and a clear ethical statement of conduct may help but emotional issues appear more complex.