bluuebunny/crossref_metadata_2025_split huggingface dataset:
A mathematical model of a cc-type single-screw compressor
Authors: Yang S-C 
Published: April 2011

In this paper, a method is proposed for determining a basic profile of a cc-type single-screw compressor including the gate rotor and the screw rotor. The cc-type has a cylindrical screw and two cylindrical gate rotors. Based on this method, a mathematical model of the meshing principles of a cc-type screw rotor meshed with a gate rotor, that has either straight edge teeth or conical teeth, is presented. The inverse envelope concept is used to determine the cutting-edge curve of a gate rotor. Based on this concept, the required cutter for machining a cc-type screw rotor can be obtained by the envelope of a one-parameter family. The obtained screw rotor is an envelope to the family of the gate rotor's surfaces. The obtained envelope becomes the generating surface. The inverse envelope can be used to obtain the envelope to the family of generating surfaces. Then the profile of a gate rotor cutting-edge curve can be easily obtained. The surface analysis including contact lines is shown for the design and manufacture of a screw compressor. As an example, the cc-type single-screw compressor with a compressor ratio of 11:6 was determined with the aid of the proposed mathematical model. Using rapid prototyping (RP) and manufacturing technology, a cc-type single-screw rotor with a gate rotor was designed. The RP primitives provide an actual full-size physical model that can be analysed and used for further development. Results from these mathematical models should have applications in the design of cc-type single-screw compressors.
Thermal design for the Beagle 2 landed test environment
Authors: Shaughnessy B M 
Published: April 2011

Beagle 2 is a British-led mission to place a scientific Lander on Mars to search for evidence of past or present life and to conduct geochemical and environmental investigations. It was launched aboard the European Space Agency's Mars Express on 2 June 2003. During 2002 tests were undertaken at the Rutherford Appleton Laboratory, UK, to verify the Lander thermal design under simulated Martian environmental conditions. A pre-requisite was the design and commissioning of the test facility required to achieve the stringent test requirements. This paper describes the development of the test facility and the supporting thermal design and analysis.
Annulus wall temperatures and heat transfer coefficients in aeroengine compressors deduced from engine measurements
Authors: Lewis L , Provins J , Fisher L 
Published: April 2011

Surface-mounted thermocouples were located on the annulus walls of every stator stage in both core compressors of a large civil aeroengine. The relationships of the steady state wall temperatures to the compressor inlet and exit air temperatures are shown, as is their variation with engine rotational speed. The transient response of the thermocouples to fast engine throttle manoeuvres was measured, for acceleration to full power, deceleration to idle and for both acceleration and deceleration to two intermediate power levels. Heat transfer coefficients are deduced from the matching of a thermal finite element model to the measured transients and are expressed as factors with respect to the standard free-disc formula. The variations in the factors through the compressor and through the speed range are shown. The advantages and disadvantages of using an alternative standard formula, based on duct flow, are discussed. Finally, the importance of understanding the transient local air temperature response arriving at a compressor stage due to upstream slugging is shown.
Evaluating waste vegetable oils as a diesel fuel
Authors: Murayama T , Fujiwara Y , Noto T 
Published: April 2011

The research into turning a vegetable oil into an alternative fuel has been underway for some time [1-5]. Although some countries have begun to use some biomass as a fuel for the automobile, the wide use of an alternative fuel has been difficult without substantial subsidies owing to the cost of the biomass which is 3-5 times higher than that of fossil fuel. However, the cost of waste vegetable oil is competitive with that of fossil fuel and, in the collection of waste vegetable oil, there is an additional advantage of being able to prevent its illegal dumping. Furthermore, the reuse of the oil will improve the profitability of its collection. This research focused on the engine performance and emission characteristics of methyl-esterified vegetable oil when it is used in a diesel engine of an automobile. The research conducted with direct injection (DI) and indirect injection (IDI) diesel engines revealed that, for engine performance, the alternative fuel was on a par with light oil. For the emission of particulates, with the IDI diesel engine there was no significant difference between the light oil; however, the DI engine proved to emit a much larger quantity of particulates in the low to middle load range. The research also revealed the necessity for countermeasures against solidification of the fuel during the winter months, the generation and emission of aldehyde and benzene, which are typical of oxygenated fuel, and the tempuralike smell caused by propionaldehyde.
Vibration monitoring as a predictive maintenance tool for reciprocating engines
Authors: deBotton G , Ben-Ari J , Sher E 
Published: April 2011

The vibration signature of a four-stroke, four-cylinder carburetted spark ignition engine has been analysed. The significance and contribution of the signature components with respect to the overall information about the engine health have been explored. The engine block vibrations were recorded at four different locations, two in the vicinity of the rear crankshaft bearing and two at opposing sides of the engine block. The vibrations were measured along the three principal axes. It was found that the engine block side is the most sensitive location for collecting data and the direction transverse to the pistons’ movement plane is the most informative one. For the sake of simplicity in possible practical applications in the future the tests were conducted under idle conditions. The measured vibration waveform has been synchronized with the crankshaft position by using the primary coil signal and then transformed to the frequency domain by a fast Fourier transform procedure. Frequencies below 1 Hz and above 10 kHz were filtered out. A reliable data persistence was obtained by averaging eight spectra. Spectral analyses of several common faults, such as disconnected spark plug, early spark timing, late spark timing, worn spark plug, fouled spark plug and loose support, have been carried out. Reflections of these faults have been revealed in the vibration signature. General evaluation criteria for the engine's health have been proposed. For example, the appearance of vibration components with unusual frequencies can provide an early warning that the engine is operating at abnormal conditions. The appearance of peaks at one-half or three-halves of the fundamental frequency indicates that a severe malfunction has developed in the engine. The appearance of a peak at the fundamental frequency implies that a mechanical looseness enables the engine to vibrate at the crankshaft frequency. In general terms, dispersion of the energy at subharmonic frequencies, or at six to eight times the fundamental frequency, indicates a developing malfunction.
Designing composite structures for optimum in-service performance with reference to the Firefly aircraft and the Jetstream baggage pod
Authors: Foster N G 
Published: April 2011

When designing high-quality composites that are optimized for cost, weight and durability, the advantages and disadvantages of the materials used must be considered. This paper will discuss problems expected in the life of a composite structure, as well as the airworthiness certification of composites. In the last 20 years of Slingsby composite design and manufacture, no noteworthy in-service problems have occurred. The emphasis in this paper will therefore be on how potential in-service problems are covered by careful design and testing. The discussion of in-service performance of composites will concentrate on Slingsby Aviation's experience with the design, testing and manufacture of the Firefly all-composite aircraft. The Firefly is a two-seat aerobatic training aircraft manufactured using glass fibre and hand wet lay-up techniques. Reference will also be made to Slingsby test data relating to the performance of glass/Kevlar/Nomex honeycomb structures. This type of structure is used in the ventral baggage pod for the Jetstream 41 aircraft.
Woven composite design for extreme events using a damage mechanics methodology
Authors: Iannucci L 
Published: April 2011

Current predictive techniques for the analysis of composite structures and components near and beyond their ultimate strength are simplistic, using basic failure functions and traditional failure envelopes to determine the degree of damage in some arbitrary composite component or structure subjected to a biaxial or triaxial loading regime. Similarly, the design procedure usually assumes that the composite structure remains elastic throughout any potential applied loading. The analysis methodology proposed in this paper reflects a state-of-the-art dynamic modelling technique based on finite elements (FE) that can be used to model a wide range of problems, from extreme events, such as an explosion, to non-linear static problems that can occur near discontinuities or free edges. The damage mechanics approach presented in this paper uses a scalar damage variable assigned to each observed damage mode. As damage is cumulative and related to the engineering constants, such as the Young's modulus, the technique allows initial and/or post-dynamic static loads to be applied to the composite structure or component, so potentially a cradle-to-grave composite design methodology could be developed. The forms of the stress-strain curve for woven glass composite and the relevance of experimentally measured material damage constants are discussed. The proposed damage mechanics approach has been implemented as a new material failure model in the explicit dynamic DYNA3D FE code. Results are presented for two high-velocity (bird strike) impact events on a woven glass composite.
Systematic Review of the Balance Error Scoring System
Authors: Bell David R. , Guskiewicz Kevin M. , Clark Micheal A. , Padua Darin A. 
Published: April 2011

Context: The Balance Error Scoring System (BESS) is commonly used by researchers and clinicians to evaluate balance.A growing number of studies are using the BESS as an outcome measure beyond the scope of its original purpose. Objective: To provide an objective systematic review of the reliability and validity of the BESS. Data Sources: PubMed and CINHAL were searched using Balance Error Scoring System from January 1999 through December 2010. Study Selection: Selection was based on establishment of the reliability and validity of the BESS. Research articles were selected if they established reliability or validity (criterion related or construct) of the BESS, were written in English, and used the BESS as an outcome measure. Abstracts were not considered. Results: Reliability of the total BESS score and individual stances ranged from poor to moderate to good, depending on the type of reliability assessed. The BESS has criterion-related validity with force plate measures; more difficult stances have higher agreement than do easier ones. The BESS is valid to detect balance deficits where large differences exist (concussion or fatigue). It may not be valid when differences are more subtle. Conclusions: Overall, the BESS has moderate to good reliability to assess static balance. Low levels of reliability have been reported by some authors. The BESS correlates with other measures of balance using testing devices. The BESS can detect balance deficits in participants with concussion and fatigue. BESS scores increase with age and with ankle instability and external ankle bracing. BESS scores improve after training.
Smad4 binds Hoxa9 in the cytoplasm and protects primitive hematopoietic cells against nuclear activation by Hoxa9 and leukemia transformation
Authors: Quéré Ronan , Karlsson Göran , Hertwig Falk , Rissler Marianne , Lindqvist Beata , Fioretos Thoas , Vandenberghe Peter , Slovak Marilyn L. , Cammenga Jörg , Karlsson Stefan 
Published: April 2011

AbstractWe studied leukemic stem cells (LSCs) in a Smad4−/− mouse model of acute myelogenous leukemia (AML) induced either by the HOXA9 gene or by the fusion oncogene NUP98-HOXA9. Although Hoxa9-Smad4 complexes accumulate in the cytoplasm of normal hematopoietic stem cells and progenitor cells (HSPCs) transduced with these oncogenes, there is no cytoplasmic stabilization of HOXA9 in Smad4−/− HSPCs, and as a consequence increased levels of Hoxa9 is observed in the nucleus leading to increased immortalization in vitro. Loss of Smad4 accelerates the development of leukemia in vivo because of an increase in transformation of HSPCs. Therefore, the cytoplasmic binding of Hoxa9 by Smad4 is a mechanism to protect Hoxa9-induced transformation of normal HSPCs. Because Smad4 is a potent tumor suppressor involved in growth control, we developed a strategy to modify the subcellular distribution of Smad4. We successfully disrupted the interaction between Hoxa9 and Smad4 to activate the TGF-β pathway and apoptosis, leading to a loss of LSCs. Together, these findings reveal a major role for Smad4 in the negative regulation of leukemia initiation and maintenance induced by HOXA9/NUP98-HOXA9 and provide strong evidence that antagonizing Smad4 stabilization by these oncoproteins might be a promising novel therapeutic approach in leukemia.
Protein disulfide isomerase blocks CEBPA translation and is up-regulated during the unfolded protein response in AML
Authors: Haefliger Simon , Klebig Christiane , Schaubitzer Kerstin , Schardt Julian , Timchenko Nikolai , Mueller Beatrice U. , Pabst Thomas 
Published: April 2011

AbstractDeregulation of the myeloid key transcription factor CEBPA is a common event in acute myeloid leukemia (AML). We previously reported that the chaperone calreticulin is activated in subgroups of AML patients and that calreticulin binds to the stem loop region of the CEBPA mRNA, thereby blocking CEBPA translation. In this study, we screened for additional CEBPA mRNA binding proteins and we identified protein disulfide isomerase (PDI), an endoplasmic reticulum (ER) resident protein, to bind to the CEBPA mRNA stem loop region. We found that forced PDI expression in myeloid leukemic cells in fact blocked CEBPA translation, but not transcription, whereas abolishing PDI function restored CEBPA protein. In addition, PDI protein displayed direct physical interaction with calreticulin. Induction of ER stress in leukemic HL60 and U937 cells activated PDI expression, thereby decreasing CEBPA protein levels. Finally, leukemic cells from 25.4% of all AML patients displayed activation of the unfolded protein response as a marker for ER stress, and these patients also expressed significantly higher PDI levels. Our results indicate a novel role of PDI as a member of the ER stress–associated complex mediating blocked CEBPA translation and thereby suppressing myeloid differentiation in AML patients with activated unfolded protein response (UPR).
The antifibrinolytic function of factor XIII is exclusively expressed through α2-antiplasmin cross-linking
Authors: Fraser Steven R. , Booth Nuala A. , Mutch Nicola J. 
Published: April 2011

AbstractFactor XIII (FXIII) generates fibrin-fibrin and fibrin-inhibitor cross-links. Our flow model, which is sensitive to cross-linking, was used to assess the effects of FXIII and the fibrinolytic inhibitor, α2-antiplasmin (α2AP) on fibrinolysis. Plasma model thrombi formed from FXIII or α2AP depleted plasma lysed at strikingly similar rates, 9-fold faster than pooled normal plasma (PNP). In contrast, no change was observed on depletion of PAI-1 or thrombin activatable fibrinolysis inhibitor (TAFI). Inhibition of FXIII did not further enhance lysis of α2AP depleted thrombi. Addition of PNP to FXIII or α2AP depleted plasmas normalized lysis. Lysis rate was strongly inversely correlated with total cross-linked α2AP in plasma thrombi. Reconstitution of FXIII into depleted plasma stabilized plasma thrombi and normalized γ-dimers and α-polymers formation. However, the presence of a neutralizing antibody to α2AP abolished this stabilization. Our data show that the antifibrinolytic function of FXIII is independent of fibrin-fibrin cross-linking and is expressed exclusively through α2AP.
Microbial evaluation of proton-pump inhibitors and the risk of pneumonia
Authors: Meijvis S.C.A. , Cornips M.C.A. , Voorn G.P. , Souverein P.C. , Endeman H. , Biesma D.H. , Leufkens H.G.M. , van de Garde E.M.W. 
Published: April 2011

Recent initiation of proton-pump inhibitor (PPI) treatment may increase the risk of community-acquired pneumonia (CAP), hypothetically by allowing colonisation of the oropharynx by gastrointestinal bacteria. The aim of this study was to assess the causal pathway by considering microbial aetiology of pneumonia and indications for initiation of PPI treatment.This was a population-based, case–control study with 430 cases with pneumonia and 1,720 matched controls. An elaborate diagnostic protocol was used to identify the causative microorganism of pneumonia. For patients recently starting PPI treatment, indications for treatment were assessed.Recent initiation of PPI treatment (<30 days) was associated with an increased risk of CAP (adjusted OR 3.1, 95% CI 1.4–7.1). Oropharyngeal bacteria were evenly distributed among current users, past users and nonusers of PPIs (p=0.41). Gastrointestinal bacteria were identified in only five (1.2%) patients with pneumonia (two current users and three nonusers). Excluding patients who were possibly prescribed PPI treatment for early symptoms of pneumonia (protopathic bias) did not alter the study findings.This study reaffirmed that use of PPIs is associated with an increased risk of CAP, especially when treatment has recently been started. Neither protopathic bias nor shifts in microbial aetiology seem to explain the association.
Computed tomography score and pulmonary function in infants with chronic lung disease of infancy
Authors: Sarria E.E. , Mattiello R. , Rao L. , Wanner M.R. , Raske M.E. , Tiller C. , Kimmel R. , Tepper R.S. 
Published: April 2011

Chronic lung disease of infancy (CLDI) remains a common outcome among infants born extremely prematurely. In older children and adults with lung disease, pulmonary function and computed tomography (CT) scores are used to follow up respiratory disease and assess disease severity. For infants and toddlers, however, these outcomes have been used very infrequently and most often, a dichotomous respiratory outcome (presence or absence of CLDI) is employed.We evaluated the performance of CT score and pulmonary function to differentiate infants and toddlers with CLDI from a control group.CT scans, forced expiratory flows and pulmonary diffusing capacity were obtained in 39 CLDI patients and 41 controls (aged 4–33 months). CT scans were quantified using a scoring system, while pulmonary function was expressed as Z-scores. CT score outperformed pulmonary function in identifying those with CLDI. There were no significant correlations between CT score and pulmonary function.CT score had a better performance than pulmonary function in differentiating individuals with CLDI; however, these outcomes may reflect differing components of the pulmonary pathophysiology of CLDI. This new information on pulmonary outcomes can assist in designing studies with these parameters. Future studies will be required to evaluate which of the outcomes can better detect improvement with therapeutic intervention and/or lung growth.
Occurrence of multipolar mitoses and association with Aurora-A/-B kinases and p53 mutations in aneuploid esophageal carcinoma cells
Authors: Fichter Christiane D , Herz Corinna , Münch Claudia , Opitz Oliver G , Werner Martin , Lassmann Silke 
Published: April 2011

Abstract

Background
Aurora kinases and loss of p53 function are implicated in the carcinogenesis of aneuploid esophageal cancers. Their association with occurrence of multipolar mitoses in the two main histotypes of aneuploid esophageal squamous cell carcinoma (ESCC) and Barrett's adenocarcinoma (BAC) remains unclear. Here, we investigated the occurrence of multipolar mitoses, Aurora-A/-B gene copy numbers and expression/activation as well as p53 alterations in aneuploid ESCC and BAC cancer cell lines.

Results
A control esophageal epithelial cell line (EPC-hTERT) had normal Aurora-A and -B gene copy numbers and expression, was p53 wild type and displayed bipolar mitoses. In contrast, both ESCC (OE21, Kyse-410) and BAC (OE33, OE19) cell lines were aneuploid and displayed elevated gene copy numbers of Aurora-A (chromosome 20 polysomy: OE21, OE33, OE19; gene amplification: Kyse-410) and Aurora-B (chromosome 17 polysomy: OE21, Kyse-410). Aurora-B gene copy numbers were not elevated in OE19 and OE33 cells despite chromosome 17 polysomy. Aurora-A expression and activity (Aurora-A/phosphoT288) was not directly linked to gene copy numbers and was highest in Kyse-410 and OE33 cells. Aurora-B expression and activity (Aurora-B/phosphoT232) was higher in OE21 and Kyse-410 than in OE33 and OE19 cells. The mitotic index was highest in OE21, followed by OE33 > OE19 > Kyse-410 and EPC-hTERT cells. Multipolar mitoses occurred with high frequency in OE33 (13.8 ± 4.2%), followed by OE21 (7.7 ± 5.0%) and Kyse-410 (6.3 ± 2.0%) cells. Single multipolar mitoses occurred in OE19 (1.0 ± 1.0%) cells. Distinct p53 mutations and p53 protein expression patterns were found in all esophageal cancer cell lines, but complete functional p53 inactivation occurred in OE21 and OE33 only.

Conclusions
High Aurora-A expression alone is not associated with overt multipolar mitoses in aneuploid ESCC and BAC cancer cells, as specifically shown here for OE21 and OE33 cells, respectively. Additional p53 loss of function mutations are necessary for this to occur, at least for invasive esophageal cancer cells. Further assessment of Aurora kinases and p53 interactions in cells or tissue specimens derived from non-invasive dysplasia (ESCC) or intestinal metaplasia (BAC) are necessary to disclose a potential causative role of Aurora kinases and p53 for development of aneuploid, invasive esophageal cancers.