bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of High-Speed/High-Voltage SMA Actuation
Authors: Motzki Paul , Gorges Tom , Würtz Thomas , Seelecke Stefan 
Published: November 2017

The thermal shape memory effect describes the ability of a deformed material to return to its original shape when heated. This effect is found in shape memory alloys (SMAs) such as nickel-titanium (NiTi). SMA actuator wire is known for its high energy density and allows for the construction of compact systems. An additional advantage is the so-called “self-sensing” effect, which can be used for sensor tasks within an actuator-sensor-system.
In most applications, a current is used to heat the SMA wires through joule heating. Usually a current between zero and four ampere is recommended by the SMA wire manufacturers depending on the wire diameter. Therefore, supply voltage is adjusted to the SMA wire’s electrical resistance to reach the recommended current.
The focus of this work is to use supply voltages of magnitudes higher than the recommended supply voltages on SMA actuator wires. This actuation method has the advantage of being able to use industry standard voltage supplies for SMA actuators. Additionally, depending on the application, faster actuation and higher strokes can be achieved.
The high voltage results in a high current in the SMA wire. To prevent the wire from being destroyed by the high current, short pulses in the micro- and millisecond range are used.
As part of the presented work, a test setup has been constructed to examine the effects of the crucial parameters such as supply voltage amplitude, pulse duration, wire diameter and wire pre-tension. The monitored parameters in this setup are the wire displacement, wire current and force generated by the SMA wire. All sensors in this setup and their timing is validated through several experiments. Additionally, a highspeed optical camera system is used to record qualitative videos of the SMA wire’s behavior under there extreme conditions. This optical feedback is necessary to fully understand and interpret the measured force and displacement signals.
Nonreciprocal Acoustics Using Programmable Boundary Conditions: From Boundary Control and Active Metamaterials to the Acoustic Diode
Authors: Karkar Sami , Collet Manuel 
Published: November 2017

In this communication, we first introduce the concept of programmable boundary conditions, and then use it to design a nonreciprocal acoustic device: an effective, broadband, acoustic diode.
Previous works showed that, using sufficiently small transducers, an active acoustic metasurface can be realized: a smart active acoustic skin with tunable acoustic properties. Using distributed control, these properties can be adapted or reconfigured in real-time. Or, it can even depend on the acoustic field itself, allowing for a programming of the (meta)surface properties: a programmable boundary condition. For instance, a partial derivative equation depending on the acoustic quantities can be imposed, in a discretized form, at the surface of such a programmable boundary. This type of non-standard boundary conditions have been shown to provide the necessary basis for nonreciprocal propagation for a plane wave interacting with a boundary with non grazing incidence, ie. for wavevectors that possess a component normal to the boundary. This restriction may appear problematic when the wavevector is then parallel to the boundary, e.g. when dealing with plane waves in a 1D waveguide, as in an acoustic diode.
An acoustic diode, or acoustic isolator, is a nonreciprocal device that let acoustic power pass only in one direction, hence breaking the reciprocity of normal acoustic propagation. We propose a new model of acoustic diode, based on active components: a continuous, distributed source inside the domain. However, based on the modeling of parietal sources in ducts, in the low frequency range, we show that the boundary control approach and the distributed domain sources are equivalent. The only difference is that, in the case of the programmable boundary condition, the near-field of the boundary also contains a component normal to the boundary. Hence our acoustic diode can be realized in practice using programmable boundary conditions. Moreover, the acoustic diode is effective on a broad frequency range, since it can work both on the fundamental mode (plane waves) and on higher-order mode of the waveguide.
Dynamic Finite Element Modelling of a Hydrogel-Based Micro-Valve With 2-Way Fluid Structure Interactions
Authors: Mehner Philipp J. , Beck Anthony , Voigt Andreas , Marschner Uwe , Richter Andreas 
Published: November 2017

We propose a finite element model which describes the dynamic behavior of hydrogels for step-responses and quasi-static regimes. The material properties are implemented in a fluid structure interaction (FSI) model which simulates the swelling behavior of hydrogels within a micro-valve. The resulting volume change effects the fluid domain describing the mass-flow behavior of the micro-valve. Furthermore, the concept is implemented in a high-level circuit and flow chart model to efficiently predict the response behavior of hydrogel-based micro-valves.
With these tools a foundation is set to efficiently simulate microfluidic systems with the aim to develop a fully computer-aided design process. The presented method will help to better understand, predict and visualize the behavior of hydrogels and support the development of highly integrated hydrogel-based microfluidic circuits.
A Comparative Study of Surface Cleaning Treatments for 3D Printed Medical Implants
Authors: Guo Lucy , Xie Zhiqiang , Yao Hong , Wang Ying 
Published: November 2017

In the field of Additive Manufacturing (AM), one of the major applications of laser-based 3D metal printing is the creation of custom implants for medical purposes. However, a significant challenge in the manufacturing of implants using Selective Laser Melting (SLM) is the formation of partially melted particles on the surface of medical implants. These particles result in a multitude of issues including plurality of structurally weak points on the designed implants, obstruction of important design features, and possibility of dislodgement over the service life span, thereby posing a threat to the recipient. To address the above challenges, it is imperative to develop a simple but effective surface cleaning method to remove partially melted particles from the surface without damage to the designed medical implants.
In this work, a comparative study was conducted to investigate the effect of both chemical and electro-plasma based cleaning processes on the removal of partially melted particles from the surfaces of 3D printed Ti-6Al-4V medical screw implants. These techniques include chemically polishing implants with HF-HNO3 acid solutions and using an electro-plasma based cleaning process. With the field of additive manufacturing rapidly expanding, this work offers valuable insight on proper post-process treatment of 3D printed parts for future medical purposes in biomedical fields.
Constitutive Modeling of Patterned Liquid Crystal Elastomer for Active Flow Control
Authors: Beblo Richard , Settle Michael , Guin Tyler , White Timothy , Reich Gregory 
Published: November 2017

Patterned liquid crystal elastomer (LCE) has been shown to have significant promise in surface topography control. Large and diverse shapes and surface adaptive responses have been shown using LCE materials with patterned director profiles. Using various techniques, crystal orientation across the surface of the material as well as through the thickness can be achieved yielding the capability to design out-of-plane deformation. These topological features can be used as active flow effectors manipulating, among other things, drag on an object in cross-flow.
It is well known that surface topography can have a large effect on skin friction drag by effecting the boundary layer transition, separation, and interfering with the shedding of vortices. In regards to a cylinder in a cross-flow, spatially manipulating surface topography, and thus drag, in this way gives rise to forces exerted by the fluid on the body. An imbalance of forces due to non-uniform surface topography can then be used to control the cylinder.
Designing such a system requires optimization of the surface topography via optimization of the crystal orientation pattern over a wide range of environments. Key to this optimization, described in detail in the presented work, is an accurate material model validated against experimental data. By representing the strain energy of the material as a combination of contributions of the elastomer backbone and the liquid crystals separately, unique material properties can be properly modeled. This is achieved by combining a traditional isotropic 3 chain Arruda-Boyce hyperelastic equation modeling the elastomer backbone with an anisotropic extension modeling the patterned liquid crystals, resulting in an anisotropic hyperelastic material model. The model can then be used to predict the material response of various patterns and investigate the design space of possible surface topographies.
One Way Sound Propagation in a Smart Fluid
Authors: Nanda Aditya , Karami M. Amin 
Published: November 2017

This manuscript investigates one way sound propagation in Magnetorheological fluids (MRF) using spatio-temporal modulation of the applied magnetic field. One-way propagation of waves in a structure can have potential technological applications such as sound isolation, filtering and echo suppression. Several experimental works in the literature have shown that elastic properties of MRF’s (local speed of sound, in particular) are dependent on the applied magnetic field. Therefore, several fascinating possibilities regarding the manipulation of sound waves in MRF, by tailoring the applied magnetic field, exist.
A effective medium approximation (previously used in literature) is used to analyze sound propagation in a MRF composed of hydrogen-reduced Iron particles suspended in pure glycerine. Floquet-Bloch theory is used to obtain a quadratic eigenvalue problem that gives the band structure as a function of the material and modulation parameters. When the applied magnetic field is allowed to vary only in space, regular bandgaps are obtained as a result of Bragg scattering. In contrast, the temporal variation of the magnetic field to induce a traveling wave like variation of the modulated parameters, breaks the symmetry of the Brilloouin zones and we obtain directional bandgaps. The theoretical band structure is validated by numerical band diagrams obtained using a Finite Element code. This research has important applications in active sound manipulation.
Improving High-Speed Nanomaterials Printing With Sub-Process-Decoupled Gravure Printer Design
Authors: Scheideler William , Subramanian Vivek 
Published: November 2017

Printing technologies are attractive methods for high-throughput additive manufacturing of nanomaterials-based thin film electronics. Roll-to-roll (R2R) compatible techniques such as gravure printing can operate at high-speed (1–10 m/s) and high-resolution (< 10 μm) to drive down manufacturing costs and produce higher quality flexible electronic devices. However, large-scale deployment of printed wireless sensors, flexible displays, and wearable electronics, will require greater understanding of the printing physics of nanomaterial-based inks in order to improve the resolution, reliability, and uniformity of printed systems.
In this study, we designed and constructed a custom sheet-fed gravure printer which features registered multilayer printing for nanomaterial exploration and thin film device development. The design allows precise, independent control of the speeds and forces of each of the subprocesses of gravure (ink filling, wiping, and transfer), enabling novel experimental controls for dissecting the printing process fluid mechanics. We use these new capabilities to investigate the primary artifacts which distort printed nanomaterial patterns, such as dragout tails, edge roughness, and pinholes. These artifacts are studied as a function of print parameters such as contact pressure, wiping speed, and transfer speed, by printing silver nanoparticle ink to form continuous features with dimensions in the range of 100 μm to 10 mm. We found that the contact mechanics of the ink transfer process have a strong influence on the formation of dragout artifacts, indicating the presence of a transfer-driven squeezing flow which distorts the trailing edges of features. By engineering the transfer contact mechanics with varying rubber substrate backing stiffness, we found it is also possible to suppress this artifact formation for a particular nanomaterial ink. The improved areal uniformity and print quality achieved using these methods highlight the potential for gravure printing to be a versatile nano-manufacturing tool for patterning a variety of thin film smart materials. We also hope that the open-source printer designs presented here can serve to accelerate the development of high-speed nanomaterial printing.
Ruthenium-106 brachytherapy for iris and iridociliary melanomas
Authors: Marinkovic Marina , Horeweg Nanda , Laman Mirjam S , Bleeker Jaco C , Ketelaars Martijn , Peters Femke P , Luyten Gre P M , Creutzberg Carien L 
Published: November 2017

Background and purposeTo evaluate ruthenium-106 (Ru106) brachytherapy as eye-conserving treatment of iris melanomas (IMs) and iridociliary melanomas (ICMs).Materials and methodsEighty-eight patients received Ru106 brachytherapy between 2006 and 2016. Primary outcome was local control, and secondary outcomes were metastasis, survival, eye preservation, complications and visual acuity (VA).ResultsOverall median follow-up was 36 months. Of 88 patients, 58 (65.9%) had IM and 30 (34.1%) had ICM. ICM were on average larger and more advanced than IM. Local failure-free survival at 3years was 98.9% (SE 1.2%). Metastasis-free survival was 98.2% (SE 1.8%) at 3years; no deaths due to melanoma occurred during follow-up. Eye preservation rate was 97.7%. Treatment-related toxicities were mostly mild and observed in 80.7% of the patients. Common toxicities were worsening of pre-existing or new cataract (51.1%), dry eyes (29.5%) and glaucoma (20.5%). VA was not affected by Ru106 brachytherapy, with only 2.3% having VA <0.33 (low vision) at follow-up.ConclusionsRu106 for IM and ICM yielded excellent local control (98.9%) and eye preservation (97.7%). Toxicities were common, but mostly mild and transient. Moreover, Ru106 did not affect visual acuity.
Clinical characteristics and prognosis of drug-associated acute respiratory distress syndrome compared with non-drug-associated acute respiratory distress syndrome: a single-centre retrospective study in Japan
Authors: Anan Keisuke , Ichikado Kazuya , Kawamura Kodai , Johkoh Takeshi , Fujimoto Kiminori , Suga Moritaka 
Published: November 2017

ObjectivesTo report the clinical features and prognosis of drug-associatedacute respiratory distress syndrome (ARDS).DesignA retrospective analysis of data collected during a prospective cohort study.SettingIntensive care unit in a teaching hospital.ParticipantsA total of 197 Japanese patients with ARDS diagnosed by the Berlin definition who were admitted to the Division of Respiratory Medicine from October 2004 to December 2015 were enrolled in the study and were classified as two groups according to their causes: a drug-associated ARDS group (n=27) and a non-drug-associated ARDS group (n=170). Primary outcome measure is 28-day mortality, and the secondaryoutcome measure is ventilator-free days.ResultsThe Acute Physiology and Chronic Health Evaluation II scores were significantly lower in the drug-associated ARDS group than in the non-drug-associated ARDS group (median (IQR): 18.0 (16.5–21.0) vs 23.0 (18.0–26.0), p<0.001), and the arterial oxygen tension/fractional inspired oxygen ratio was higher (148.0 (114.1–177.5) vs 101.0 (71.5–134.0), p=0.003). In the drug-associated ARDS group, although high-resolution CT scores indicative of the extent of fibroproliferation (301.6 (244.1–339.8) vs 208.3 (183.4–271.6), p<0.001), serum lactate dehydrogenase levels (477 (365–585) vs 322 (246–434), p=0.003) and the McCabe scores (score 1/2/3, n (%): 20 (74)/4 (15)/3 (11)vs154 (91)/7 (4)/9 (5), p=0.04) were significantly higher, ventilator weaning was earlier (p<0.001) and 28-day mortality was better (p=0.043). After adjusting for potentially confounding covariates, drug-associated ARDS group was associated with lower 28-day mortality (adjusted HR (HR) 0.275; 95% CI 0.106 to 0.711; p=0.008).ConclusionsAlthough more severe lung damage with fibroproliferation was observed in patients with drug-associated ARDS, ventilator weaning was earlier, and their prognosis was better than the others. Further well-designed prospective studies are needed.
Impact of heterogeneity and effect size on the estimation of the optimal information size: analysis of recently published meta-analyses
Authors: Garcia-Alamino Josep M , Bankhead Clare , Heneghan Carl , Pidduck Nicola , Perera Rafael 
Published: November 2017

ObjectiveTo estimate the proportion of systematic reviews that meet the optimal information size (OIS) and assess the impact heterogeneity and effect size have on the OIS estimate by type of outcome (eg, mortality, semiobjective or subjective).MethodsWe carried out searches of Medline and Cochrane to retrieve meta-analyses published in systematic reviews from 2010 to 2012. We estimated the OIS usingTrial Sequential Analysissoftware (TSA V.0.9) and based on several heterogeneity and effect size scenarios, stratifying by type of outcome (mortality/semiobjective/subjective) and by Cochrane/non-Cochrane reviews.ResultsWe included 137 meta-analyses out of 218 (63%) potential systematic reviews (one meta-analysis from each systematic review). Of these reviews, 83 (61%) were Cochrane and 54 (39%) non-Cochrane. The Cochrane reviews included a mean of 6.5 (SD 6.1) studies and the non-Cochrane included a mean of 13.2 (SD 10.2) studies. The mean number of patients was 2619.1 (SD 6245.8 or median 586.0) for the Cochrane and 19 888.5 (SD 32 925.7 or median 6566.5) patients for the non-Cochrane reviews. The percentage of systematic reviews that achieved the OIS for all-cause mortality outcome were 0% Cochrane and 25% for non-Cochrane reviews; for semiobjective outcome 17% for Cochrane and 46% for non-Cochrane reviews and for subjective outcome 45% for Cochrane and 72% for non-Cochrane reviews.ConclusionsThe number of systematic reviews that meet an optimal information size is low and varies depending on the type of outcome and the type of publication. Less than half of primary outcomes synthesised in systematic reviews achieve the OIS, and therefore the conclusions are subject to substantial uncertainty.
A nationwide population-based cohort study of peripartum hysterectomy and arterial embolisation in Belgium: results from the Belgian Obstetric Surveillance System
Authors: Vandenberghe Griet , Guisset Marine , Janssens Iris , Leeuw Virginie Van , Roelens Kristien , Hanssens Myriam , Russo Erika , Van Keirsbilck Joachim , Englert Yvon , Verstraelen Hans 
Published: November 2017

ObjectivesTo assess the prevalence of major obstetric haemorrhage managed with peripartum hysterectomy and/or interventional radiology (IR) in Belgium. To describe women characteristics, the circumstances in which the interventions took place, the management of the obstetric haemorrhage, the outcome and additional morbidity of these women.DesignNationwide population-based prospective cohort study.SettingEmergency obstetric care. Participation of 97% of maternities covering 98.6% of deliveries in Belgium.ParticipantsAll women who underwent peripartum hysterectomy and/or IR procedures in Belgium between January 2012 and December 2013.ResultsWe obtained data on 166 women who underwent peripartum hysterectomy (n=84) and/or IR procedures (n=102), corresponding to 1 in 3030 women undergoing a peripartum hysterectomy and another 1 in 3030 women being managed by IR, thereby preserving the uterus. Seventeen women underwent hysterectomy following IR and three women needed further IR despite hysterectomy. Abnormal placentation and/or uterine atony were the reported causes of haemorrhage in 83.7%. Abnormally invasive placenta was not detected antenatally in 34% of cases. The interventions were planned in 15 women. Three women were transferred antenatally and 17 women postnatally to a hospital with emergency IR service. Urgent peripartum hysterectomy was averted in 72% of the women who were transferred, with no significant difference in need for transfusion. IR procedures were able to stop the bleeding in 87.8% of the attempts. Disseminated intravascular coagulation secondary to major haemorrhage was reported in 32 women (19%).ConclusionThe prevalence in Belgium of major obstetric haemorrhage requiring peripartum hysterectomy and/or IR is estimated at 6.6 (95% CI 5.7 to 7.7) per 10 000 deliveries. Increased clinician awareness of the risk factors of abnormal placentation could further improve the management and outcome of major obstetric haemorrhage. A case-by-case in-depth analysis is necessary to reveal whether the hysterectomies and arterial embolisations performed in this study were appropriate or preventable.
EFFECT of daily antiseptic body wash with octenidine on nosocomial primary bacteraemia and nosocomial multidrug-resistant organisms in intensive care units: design of a multicentre, cluster-randomised, double-blind, cross-over study
Authors: Meißner Anne , Hasenclever Dirk , Brosteanu Oana , Chaberny Iris Freya 
Published: November 2017

IntroductionNosocomial infections are serious complications that increase morbidity, mortality and costs and could potentially be avoidable. Antiseptic body wash is an approach to reduce dermal micro-organisms as potential pathogens on the skin. Large-scale trials with chlorhexidine as the antiseptic agent suggest a reduction of nosocomial infection rates. Octenidine is a promising alternative agent which could be more effective against Gram-negative organisms. We hypothesise that daily antiseptic body wash with octenidine reduces the risk of intensive care unit (ICU)-acquired primary bacteraemia and ICU-acquired multidrug-resistant organisms (MDRO) in a standard care setting.Methods and analysisEFFECT is a controlled, cluster-randomised, double-blind study. The experimental intervention consists in using octenidine-impregnated wash mitts for the daily routine washing procedure of the patients. This will be compared with using placebo wash mitts. Replacing existing washing methods is the only interference into clinical routine.Participating ICUs are randomised in an AB/BA cross-over design. There are two 15-month periods, each consisting of a 3-month wash-out period followed by a 12-month intervention and observation period. Randomisation determines only the sequence in which octenidine-impregnated or placebo wash mitts are used. ICUs are left unaware of what mitts packages they are using.The two coprimary endpoints are ICU-acquired primary bacteraemia and ICU-acquired MDRO. Endpoints are defined based on individual ward-movement history and microbiological test results taken from the hospital information systems without need for extra documentation. Data on clinical symptoms of infection are not collected. EFFECT aims at recruiting about 45 ICUs with about 225 000 patient-days per year.Ethics and disseminationThe study was approved by the ethics committee of the University of Leipzig (number 340/16-ek) in November 2016. Findings will be published in peer-reviewed journals.Trial registration numberDRKS-ID: DRKS00011282.