bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gadolinium contrast medium administration does not adversely affect T2*‐weighted gradient recalled echo magnetic resonance imaging of the canine brain at 1.5 Tesla
Authors: Bartels Janina , Hecht Silke , Conklin Gordon A. , Xiaocun Sun 
Published: August 2018

AbstractAs gadolinium‐based contrast agents are paramagnetic and have T2 shortening effects, they have the potential to adversely affect gradient recalled echo sequences. The aim of this prospective, cross‐sectional study was to evaluate the effects of gadolinium administration on T2*‐weighted sequence diagnostic quality and signal intensity when imaging the canine brain. A total of 100 dogs underwent brain magnetic resonance imaging (MRI) including pre‐ and postcontrast T2*‐weighted sequences acquired with a delay (Group A) or immediately (Group B) following gadolinium administration. Pre‐ and postcontrast images were subjectively compared. In dogs with intracranial enhancing masses, regions of interest were drawn on corresponding images and signal intensity ratios were calculated. The effect of degree and pattern of contrast enhancement, susceptibility artifacts, and time between contrast injection and T2*‐weighted sequence acquisition on signal intensity ratio was evaluated. Overall 31 dogs had contrast enhancing intracranial masses. Subjectively, there was no difference in image quality of T2*‐weighted sequences obtained before and after contrast medium administration. No significant signal intensity differences of intracranial contrast enhancing masses were found (Group A P = 0.9999; Group B P = 0.9992). Susceptibility artifacts did not differ in appearance, and there was no effect on calculated signal intensity ratio (P = 0.8142). Similarly, there was no effect of degree of enhancement or contrast heterogeneity on signal intensity ratio (P = 0.4413). No correlation was found between signal intensity ratio and the time to acquisition (P = 0.199). Administration of gadolinium‐based MRI contrast agents does not adversely affect T2*‐weighted imaging of the brain in dogs at 1.5 T even in the presence of contrast enhancing lesions.
Deferoxamine can prevent pressure ulcers and accelerate healing in aged mice
Authors: Bonham Clark A. , Rodrigues Melanie , Galvez Michael , Trotsyuk Artem , Stern‐Buchbinder Zachary , Inayathullah Mohammed , Rajadas Jayakumar , Gurtner Geoffrey C. 
Published: August 2018

ABSTRACTChronic wounds are a significant medical and economic problem worldwide. Individuals over the age of 65 are particularly vulnerable to pressure ulcers and impaired wound healing. With this demographic growing rapidly, there is a need for effective treatments. We have previously demonstrated that defective hypoxia signaling through destabilization of the master hypoxia‐inducible factor 1α (HIF‐1α) underlies impairments in both aging and diabetic wound healing. To stabilize HIF‐1α, we developed a transdermal delivery system of the Food and Drug Administration–approved small molecule deferoxamine (DFO) and found that transdermal DFO could both prevent and treat ulcers in diabetic mice. Here, we demonstrate that transdermal DFO can similarly prevent pressure ulcers and normalize aged wound healing. Enhanced wound healing by DFO is brought about by stabilization of HIF‐1α and improvements in neovascularization. Transdermal DFO can be rapidly translated into the clinic and may represent a new approach to prevent and treat pressure ulcers in aged patients.
Topical inhibition of PUMA signaling mitigates radiation injury
Authors: Kowzun Maria J. , Rifkin William J , Borab Zachary M. , Ellison Trevor , Soares Marc A. , Wilson Stelios C. , Lotfi Philip , Bandekar Amey , Sofou Stavroula , Saadeh Pierre B. , Ceradini Daniel J. 
Published: August 2018

AbstractRadiation therapy is an effective treatment strategy for many types of cancer but is limited by its side effects on normal tissues, particularly the skin, where persistent and progressive fibrotic changes occur and can impair wound healing. In this study, we attempted to mitigate the effects of irradiation on skin using a novel transcutaneous topical delivery system to locally inhibit p53 up‐regulated modulator of apoptosis (PUMA) gene expression with small interfering RNA (siRNA). In an isolated skin irradiation model, the dorsal skin of C57 wild‐type mice was irradiated. Prior to irradiation, PUMA and nonsense siRNA were applied via a novel hydrogel formulation to dorsal skin and reapplied weekly. Skin was harvested at multiple time points to evaluate dermal siRNA penetration, mRNA expression, protein expression, dermal thickness, subcutaneous fat, stiffness, vascular hypertrophy, SCAR index, and reactive oxygen species (ROS) generation. Murine skin treated with topical PUMA siRNA via optimized hydrogel formulation demonstrated effective PUMA inhibition in irradiated tissue at 3–4 days. Tissue stiffness, dermal thickness, vascular hypertrophy, SCAR index, ROS levels, and mRNA levels of MnSOD and TGF‐β were all significantly reduced with siPUMA treatment compared to nonsense controls. Subcutaneous fat area was significantly increased, and levels of SMAD3 and Phospho‐SMAD3 expression were unchanged. These results show that PUMA expression can be effectively silenced in vivo using a novel hydrogel lipoplex topical delivery system. Moreover, cutaneous PUMA inhibition mitigates radiation induced changes in tissue character, restoring a near‐normal phenotype independent of SMAD3 signaling.
Revisiting the Pain Resource Nurse Role in Sustaining Evidence‐Based Practice Changes for Pain Assessment and Management
Authors: Allen Emily , Williams Anne , Jennings David , Stomski Norman , Goucke Roger , Toye Christine , Slatyer Susan , Clarke Trish , McCullough Kylie 
Published: August 2018

AbstractBackgroundEffective pain management is unlikely to occur without consistent and timely assessments. To improve assessment and management of pain, ward‐based pain resource nurses were introduced in 2007 to facilitate hospital‐wide evidence‐based practice changes using three key targets. One‐year post implementation of this quality improvement project, promising results were revealed.AimsThe purpose of this study, 8 years post implementation, was to (a) evaluate sustained practice improvements in pain assessment and management, (b) assess current pain resource nurse knowledge and attitudes to pain, (c) explore characteristics of the pain resource nurse role, as well as (d) any perceived contextual changes regarding study findings.MethodsA mixed‐methods approach was used to address study aims. Quantitative data were collected from documentation audits and a “Knowledge and Attitudes Survey Regarding Pain.” Qualitative interviews explored the characteristics of the pain resource nurse role, and a focus group discussion explored the context of change.ResultsSignificant improvements were observed for the documentation of pain scores on admission and for each nursing shift. Survey results highlighted potential knowledge deficits in key practice areas, even though interview findings suggested that pain resource nurses provided a resource for peers, raised awareness of best practice, and imparted knowledge to other ward staff. An important facilitator for the pain resource nurse role was the ongoing collaboration and support from specific pain teams, and barriers to engage in the role were competing workload priorities, and limited awareness among other ward staff.Linking Evidence to ActionImplementing and sustaining evidence‐based practice change in clinical practice is challenging. Ongoing evaluation is necessary for identifying the long‐term implications of practice improvement interventions and issues that influence the adoption of evidence‐based practice. Strategies to address barriers, and to increase awareness and engagement of the pain resource nurse role with wider collaboration require further investigation.
PERCEIVING NATURAL EVIL THROUGH THE LENS OF DIVINE GLORY? A CONVERSATION WITH CHRISTOPHER SOUTHGATE
Authors: Deane‐Drummond Celia 
Published: August 2018

AbstractFinding a way to come to terms with the disvalues in the evolutionary world is a particular challenge in the light of Neo‐Darwinian theories. In this article I trace the shift in Christopher Southgate's work from a focus on theodicy to a theologian of glory. I am critical of his rejection of the tradition of the Fall, his incorporation of disvalues into the work of divine Glory, and the specific theological weight given to scientific content. I offer a critique of Holmes Rolston III's approach to the valuation of nature that I believe has influenced Southgate's theology. Constructively, I offer an alternative that seeks to recover an understanding of the origin of evil and the Adamic event that draws on the work of Paul Ricoeur. I also draw on the work of anthropologist Tim Ingold for an alternative philosophical approach to evolution which opens up a space for a recovery of the concepts of creaturely Sophia and shadow Sophia in the work of Sergius Bulgakov.
ESSAYS IN HONOR OF CHRISTOPHER SOUTHGATE: INTRODUCTION
Authors: Sollereder Bethany , Robinson Andrew 
Published: August 2018

AbstractThis article is an introduction to the special issue of Zygon in honor of Christopher Southgate. Over the years he has made many significant contributions to the field of science and religion, and contributors have gathered to celebrate him on his sixty‐fifth birthday. This introduction includes some biographical background and an outline of the issue's contents.
Numerical Modeling of Thermally-Induced Vibration in Rotor Caused by Light-Rub Against Brush Seal
Authors: Cangioli Filippo , Pennacchi Paolo , Vania Andrea , Chatterton Steven 
Published: August 2018

Clearance is of paramount importance for turbomachinery manufacturers to meet today’s aggressive power output, efficiency, and operational life goals. To minimize leakages, there are various seal types used, and new sealing concepts are in development. Because of their inherent flexibility and compliance, brush seals are capable of significantly reducing the leakage, and allow sufficient geometrical margins to accommodate design and operational variations of turbomachines.
Brush seals can be assembled at very tight or zero radial clearance or even with interference on the rotor to minimize the leakage. This means that the risk of contact between the rotor and the seal bristles exists, especially in case of zero clearance or interference. If the contact occurs, a hot-spot develops on the rotor and this may cause the vibration to diverge, resulting in a synchronous instability, the so-called Newkirk effect. The friction forces generated by rotor-to-stator rubs often cause a shaft thermal bow whose main effect on the machine dynamic behavior is a progressive change of the synchronous (1X) vibration.
The development of analytical tools able to model this phenomenon is therefore important to assess the rotordynamic stability during the design phase and avoid excessive vibrations which may have severe impact on the operability and on the mechanical integrity of the machine.
The objective of this paper is the development of a numerical model to analyze the dynamic behavior of real turbomachines subject to thermally-induced vibration caused by light-rub of the rotor against brush seals. The model developed in the paper is based on the work of Bachschmid et al. [1]: the dynamics is analyzed in the frequency domain using the standard rotordynamic model, whereas the heat transfer analysis, to calculate the temperature distribution and the associated thermal bow, is studied in the time domain. The contact analysis has been deeply revised, aiming at estimating suitable normal and tangential force and the friction heating generated by the contact. The bow determined by the thermal conditions has been reproduced using suitable bending moments, which have been applied to the beam elements in the rotordynamic model.
A Mixed-Fidelity Numerical Study for Fan-Distortion Interaction
Authors: Ma Yunfei , Cui Jiahuan , Vadlamani Nagabhushana Rao , Tucker Paul G. 
Published: August 2018

Inlet distortion often occurs at off-design points when flow separates within an intake. This unsteady phenomenon could seriously impact fan performance. Fan-distortion interaction is a highly unsteady aerodynamic phenomenon. High-fidelity simulation can provide a detailed insight into these interactions. However, due to computational resource limitations, the use of eddy resolving methods for a fully resolved fan calculation is currently infeasible for industry. To solve this problem, a mixed-fidelity CFD method is proposed. This method uses the Large Eddy Simulation (LES) to resolve the turbulence associated with separation, and the Immersed Boundary Method with Smeared Geometry (IBMSG) for the fan. The method is validated by an experiment of Darmstadt Rotor, which shows a good agreement in terms of total pressure distributions.
A detailed investigation is then conducted on a subsonic rotor with an annular beam generating inlet distortion. A range of studies are performed to investigate fan influence on distortions. Compared to the case without fan, it shows that a fan has a significant effect in reducing distortions. Three fan locations are examined. The fan nearer to the inlet tends to have a higher pressure recovery. Three beams with different heights are also tested to generate various degrees of distortions. The results indicate that the fan can suppress the distortions and its recovery effect is proportional to the degree of inlet distortion.
A Test Rig Concept to Study Fluid Structure Interactions in a Steam Turbine Valve
Authors: Wallat Stefan , Domnick Clemens B. , Musch Christian , Brillert Dieter 
Published: August 2018

The power output of steam turbines is controlled by steam turbine inlet valves. These valves have a large flow capacity and dissipate a huge amount of energy in throttled operation mode. The dissipation process generates strong pressure fluctuations and leads to high dynamic forces potentially causing valve vibrations. A brief survey of the literature dealing with valve vibrations reveals that vibrational problems and damages mostly occur in throttled operation when jets, shocks and shear layers are present. Previous investigations of the authors reveal a feedback mechanism between the dynamic flow field and the vibrating valve plug. Depending on the flow topologies either axial or lateral forces will dominate the force spectrum.
In this paper the design of a test rig including a scaled model of a steam valve is described. As it is difficult to analyse lateral forces in conventional experiments the model is designed not only to study the flow conditions but also the lateral and axial movement of the valve plug. To investigate and model the dynamic characteristic of the valve the entire periphery including the mechanical drive, sealing etc. needs to be considered.
To ensure that fluid–structure-interactions are correctly scaled, dimensionless numbers derived with the Buckingham Pi Theorem are used as design criteria. Positions of the transmitters are selected based on results of numerical simulations.
A Multi-Fidelity Sampling Method for Efficient Design and Optimization of Centrifugal Compressor Impellers
Authors: Schemmann Christoph , Geller Marius , Kluck Norbert 
Published: August 2018

The optimization of a centrifugal compressor impeller is a challenge for established strategies and algorithms, as the interactions between the geometric design parameters and the aerodynamic and structural performance of the system are highly complex. Furthermore many geometrically valid designs are unusable in terms of structure mechanics or flow physics. Due to the complex parameter correlations, a simple limitation of the parametric space is no option, as possibly beneficial parameter combinations could be ruled out. To obtain a meaningful optimization result, the complete operation range of the compressor has to be taken into account which adds further complexities in terms of the optimization process and the computational expense. The combination of these issues leads to a complicated optimization scenario.
The aim of the presented work is the reduction of the computational expense required to generate a high quality metamodel for optimization. This goal shall be achieved by the development of a multi-fidelity sampling method. The basic idea is to use preliminary of low-fidelity information from empirical data or fast analytical methods to identify promising regions of the parameter space. Then the samples of the DOE are concentrated in these areas while still maintaining a good coverage of the whole applicable design space. This ensures that no beneficial designs are ruled out which were not recommended by preliminary information. The points of the resulting DOE are computed by CFD and FEA computations and used to generate the metamodel which is used for the optimization. The method is tested by generating a metamodel used for compressor optimization. The results are compared to an optimization using a metamodel based on a conventional Latin hypercube sampling.
Characterization of an Aircraft Auxiliary Power Unit Test Rig for Cycle Optimization Studies
Authors: Zanger Jan , Krummrein Thomas , Siebel Teresa , Roth Jürgen 
Published: August 2018

Detailed information of the thermodynamic parameters, system performance and operating behavior of aircraft APU cycles is rarely available in literature. In order to set up numeric models and study cycle modifications, validation data with well defined boundary conditions is needed. Thus, the paper introduces an APU test rig based on a Garrett GTCP36-28 with detailed instrumentation which will be used in a further step as a demonstration platform for cycle modifications. The system is characterized in the complete feasible operating range by alternating bleed air load and electric power output. Furthermore, simulations of a validated numerical cycle model are utilized to predict the load points in the operating region which were unstable during measurements. The paper reports and discusses turbine shaft speed, compressor air mass flow, fuel mass flow, efficiencies, compressor outlet pressure and temperature, turbine inlet and outlet temperature as well as exhaust gas emissions. Furthermore, the results are discussed with respect of the difference compared to a Hamilton Sundstrand APS3200.
Though the efficiencies of the GTCP36-28 are lower compared to the APS3200, the general behavior is in good agreement. In particular, the effects of separate compressors for load and power section are discussed in contrast to the GTCP36-28 system design comprising a single compressor. In general, it was shown that the GTCP36-28 is still appropriate for the utilization as a demonstration platform for cycle modification studies.
The Effects of Water Ingestion on the Tip Clearance Flow in Compressor Rotors
Authors: Yang Lu , Wu Xiaocui , Qin Desheng , Zheng Qun , Zhang Hai 
Published: August 2018

As the first core component of commercial aviation engines, compressor is likely to ingest a serious amount of liquid water into its path flow during the situation of heavy rain. Under the influence of centrifugal force, the tip region of compressor rotors may be filled with water. Unfortunately, the instability of tip clearance flow is a major reason for rotating stall. In order to explore the effects of water ingestion on the steady operating boundary of compressor, the change characteristics of tip clearance flow have been investigated in this research by using numerical simulation method. In reality, the compression process after water ingestion can be regarded as a special wet compression. Therefore, on the basis of existing wet compression study, the ingested mass flow and the mean droplet diameters were set as 1% of inlet air flow as well as 100 μm respectively to investigate how does water ingestion affects the flow field at the tip clearance of rotors.
The typical trajectory of water droplet in compressor has been researched firstly to simply understand the situation of water ingestion and to verify the reliability of some special droplet breakup models. Then, the compressor performance in two states of dry and wet have been compared to indicate that the pressure ratio and adiabatic efficiency of compressor will decrease after water ingestion. Among them, the compression efficiency drops by 1∼2% as a whole compared with the dry condition, the operating point moves forward and the surge margin reduces slightly.
The simulation results show that the presence of water droplets will change the distribution of airflow parameters along span direction, which leads to the decreases of mass flow rate and flow capacity of blade row, the increase of attack angel at tip region, and the separation of boundary layer in suction surface. Furthermore, the momentum losses caused by droplet impingement and breakup cause a sharp increase in the static entropy at the blade tip region as well. On the other hand, the ingestion of droplet brings an external disturbance to the flow, although it has some dissipated effects on the turbulence kinetic energy, it aggravates the unsteady characteristic of turbulent flow seriously at the tip region of blade.
Rotational Speed-Dependent Contact Formulation for Nonlinear Blade Dynamics Prediction
Authors: Heinze Torsten , Panning-von Scheidt Lars , Wallaschek Jörg , Hartung Andreas 
Published: August 2018

Considering rotational speed-dependent stiffness for vibrational analysis of friction-damped bladed disk models has proven to lead to significant improvements in nonlinear frequency response curve computations. The accuracy of the result is driven by a suitable choice of reduction bases. Multi-model reduction combines various bases which are valid for different parameter values. This composition reduces the solution error drastically. The resulting set of equations is typically solved by means of the harmonic balance method. Nonlinear forces are regularized by a Lagrangian approach embedded in an alternating frequency/time domain method providing the Fourier coefficients for the frequency domain solution.
The aim of this paper is to expand the multi-model approach to address rotational speed-dependent contact situations. Various reduction bases derived from composing Craig-Bampton, Rubin-Martinez, and hybrid interface methods will be investigated with respect to their applicability to capture the changing contact situation correctly. The methods validity is examined based on small academic examples as well as large-scale industrial blade models. Coherent results show that the multi-model composition works successfully, even if multiple different reduction bases are used per sample point of variable rotational speed. This is an important issue in case that a contact situation for a specific value of the speed is uncertain forcing the algorithm to automatically choose a suitable basis. Additionally, the randomized singular value decomposition is applied to rapidly extract an appropriate multi-model basis. This approach improves the computational performance by orders of magnitude compared to the standard singular value decomposition, while preserving the ability to provide a best rank approximation.