bluuebunny/crossref_metadata_2025 huggingface dataset:
Conjugate-mediated Delivery of RNAi-based Therapeutics: Enhancing Pharmacokinetics–Pharmacodynamics Relationships of Medicinal Oligonucleotides
Authors: Godinho Bruno M. D. C. , Coles Andrew H. , Khvorova Anastasia
Published: February 2019

Therapeutic gene silencing using synthetic small interfering RNA (siRNA) holds great promise for the treatment of genetically-defined disorders by targeting disease-associated gene products for degradation. To date, one of the most clinically advanced configurations in the field consists of fully chemically modified siRNAs conjugated to N-acetylgalactosamine (GalNAc), which enables targeted delivery with potent and long-lasting gene silencing effects in hepatocytes. The revolutionary success of the GalNAc platform has rapidly expanded to various clinical programs to treat liver disorders. This success has spurred much interest in the field to explore other conjugate modalities, which are now being tested for their in vivo utility to achieve meaningful delivery to extrahepatic tissues. Establishing meaningful oligonucleotide delivery and durable gene-silencing effects requires careful consideration of the key aspects that govern the pharmacokinetics–pharmacodynamics (PK–PD) of conjugated oligonucleotides. In this chapter, we provide an overview of the chemical evolution of unformulated RNA interference (RNAi)-based technologies focusing on the major corner stones that determine productive PK–PD relationships: chemical stabilization, conjugation chemistries for modulation of biodistribution, clearance and intracellular localization and the effects of the route of administration.
Nucleic Acid Innate Immune Receptors
Authors: Saitoh Shin-Ichiroh , Miyake Kensuke
Published: February 2019

Viral infection is a serious threat to humans. Nucleic acid (NA) sensing is an essential strategy to protect humans from viral infection. Currently, many intracellular NA sensors for DNA and RNA have been identified. To control viral infections, the immune system uses a variety of NA sensors, including Toll-like receptors in endolysosomes and cytosolic NA sensors. These sensors activate defence responses by inducing the production of a variety of cytokines, including type I interferons and interleukin-1 beta (IL-1β). In addition to viral NAs, self-derived NAs are released during tissue damage and activate NA sensors, which leads to a variety of inflammatory diseases. To avoid unnecessary activation of NA sensors, the processing and trafficking of NA sensors and NAs needs to be tightly controlled. The regulatory mechanisms of NA sensors and NAs have been clarified by biochemical, cell biological, and crystal structure analyses. Here, we summarize recent progress on the mechanisms controlling NA sensor activation.
Aptamers and Clinical Applications
Authors: Zon G.
Published: February 2019

This chapter provides a brief introduction to followed by discussion of recent preclinical studies on potential aptamer drugs grouped into two broad categories, namely, “aptamer structures” and “non-ocular diseases.” Examples of aptamer-based targeting of drugs are then described. Next is an overview of the status of nearly 30 clinical trials of aptamer drugs currently listed in ClinicalTrials.gov, which is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world, and is a service of the US National Institutes of Health. This overview includes brief descriptions of each study sponsor, aptamer drug, disease(s), and type of study, as well as separate tables for completed studies, withdrawn or terminated studies, and active studies. The final section discusses Conclusions and Prospects.
Biomaterials as vectors for the delivery of CRISPR–Cas9
Authors: Eoh Joon , Gu Luo
Published: February 2019

The emergence of the CRISPR–Cas9 gene editing system has generated considerable hope and excitement in the field of gene therapy and the larger scientific community. Recently, biomaterials have become an attractive option for the delivery of Cas9 due to their remarkable versatility.
A consolidated account of electrochemical determination of band structure parameters in II–VI semiconductor quantum dots: a tutorial review
Authors: Ingole Pravin Popinand
Published: February 2019

Probing absolute electronic energy levels in semiconductor quantum dots (Q-dots) is crucial for engineering their electronic band structure and hence for precise design of composite nano-structure based devices.
Ice crystallization observed in highly supercooled confined water
Authors: Stefanutti E. , Bove L. E. , Lelong G. , Ricci M. A. , Soper A. K. , Bruni F.
Published: February 2019

We investigate the state of water confined in the cylindrical pores of MCM-41 type mesoporous silica, with pore diameters of 2.8 nm and 4.5 nm, over the temperature range 160–290 K by combining small angle neutron scattering and wide angle diffraction.
Remote ion-pair interactions in Fe-porphyrin-based molecular catalysts for the hydrogen evolution reaction
Authors: Kasemthaveechok Sitthichok , Fabre Bruno , Loget Gabriel , Gramage-Doria Rafael
Published: February 2019

The influence of ion-pair interactions between carboxy-containing iron porphyrins and the proton source in the hydrogen evolution reaction is described.
Stereospecific polymerization of conjugated dienes using neodymium alkylborohydride complexes
Authors: Tanaka Ryo , Shinto Yuto , Matsuzaki Ryusei , Nakayama Yuushou , Shiono Takeshi
Published: February 2019

Two neodymium alkylborohydride complexes that differ with respect to the number of hydrides on the boron center were synthesized and characterized.
Monodispersed MnO nanoparticles in graphene-an interconnected N-doped 3D carbon framework as a highly efficient gas cathode in Li–CO2 batteries
Authors: Li Siwu , Liu Yuan , Zhou Junwen , Hong Shanshan , Dong Yu , Wang Jiaming , Gao Xing , Qi Pengfei , Han Yuzhen , Wang Bo
Published: February 2019

Monodispersed MnO nanoparticles in a 3D conductive carbon framework are designed as an effective cathode for a highly efficient, powerful and stable Li–CO2 battery.
An integrated approach for mixture analysis using MS and NMR techniques
Authors: Kuhn Stefan , Colreavy-Donnelly Simon , Santana de Souza Juliana , Borges Ricardo Moreira
Published: February 2019

We suggest an improved software pipeline for mixture analysis.
The effects of dietary selenomethionine on tissue-specific accumulation and toxicity of dietary arsenite in rainbow trout (Oncorhynchus mykiss) during chronic exposure
Authors: Jamwal Ankur , Saibu Yusuf , MacDonald Tracy C , George Graham N , Niyogi Som
Published: February 2019

The interactive effects of different doses of dietary selenium [as selenomethionine; 1.8 μg g−1 (control), 10 μg g−1 and 40 μg g−1 diet] on the toxicity of dietary arsenic [as arsenite (As3+); 80 μg As per g diet] were investigated in rainbow trout over an exposure period of 30 days. Fish fed with As3+ alone showed an increased hepatic lipid peroxidation (LPO) and a concomitant decline in cellular redox potential (determined as GSH:GSSG) in the liver tissue relative to the control fish. Interestingly, fish fed with low (10 μg g−1) or high (40 μg g−1) concentration of dietary selenomethionine in combination with As3+ showed an even higher degree of hepatic LPO and a further decrease in GSH : GSSG molar ratio relative to the fish treated with As3+ alone. Our study also revealed that exposure to dietary selenomethionine (both at low and high levels) resulted in significantly higher levels of arsenic in target tissues (liver, kidney, and muscle) relative to fish treated with As3+ alone. Similarly, the synchrotron-based X-ray fluorescence imaging analysis also suggested a dose-dependent increase in the co-localization of arsenic and selenium in the brain of fish co-treated with dietary As3+ and selenomethionine. These observations suggested that selenomethionine facilitated arsenic deposition in the brain and likely in other tissues, possibly via bio-complexation. Overall, our findings indicated that elevated dietary selenomethionine can increase the tissue-specific accumulation and toxicity of As3+ in fish during chronic dietary exposure.
V-shaped active plasmonic meta-polymers
Authors: Jana Debrina , Vasista Adarsh B. , Jog Harshvardhan , Tripathi Ravi P. N. , Allen Monica , Allen Jeffery , Pavan Kumar G. V.
Published: February 2019

A facile, cheap, and scalable method for the fabrication of V shaped plasmonic meta-polymers on a glass substrate/silicon wafer has been reported. This V shaped antenna shows unique polarization and electric field signatures and enhances molecular signatures in the near field.
A review of polystyrene bead manipulation by dielectrophoresis
Authors: Chen Qiaoying , Yuan Yong J.
Published: February 2019

Exploitation of the intrinsic electrical properties of particles has recently emerged as an appealing approach for trapping and separating various scaled particles.
Addressing the properties of “Metallo-DNA” with a Ag(i)-mediated supramolecular duplex
Authors: Mistry Liam , El-Zubir Osama , Dura Gema , Clegg William , Waddell Paul G. , Pope Thomas , Hofer Werner A. , Wright Nick G. , Horrocks Benjamin R. , Houlton Andrew
Published: February 2019

The silver-nucleoside complex [Ag(i)-(N3-cytidine)2]+, 1, self-assembles to form a supramolecular metal-mediated base-pair array highly analogous to those seen in metallo-DNA.
Primary α-tertiary amine synthesis via α-C–H functionalization
Authors: Vasu Dhananjayan , Fuentes de Arriba Angel L. , Leitch Jamie A. , de Gombert Antoine , Dixon Darren J.
Published: February 2019

A reactive ketimine intermediate was demonstrated to be intercepted by a variety of nucleophiles including organometallics and TMSCN.
PVP incorporated MoS2 as a Mg ion host with enhanced capacity and durability
Authors: Wu Canlong , Zhao Guangyu , Gong Shan , Zhang Naiqing , Sun Kening
Published: February 2019

A PVP incorporated MoS2 host with enhanced durability due to the role of PVP in tightly bridging MoS2 monolayers.
A fast and stable Li metal anode incorporating an Mo6S8 artificial interphase with super Li-ion conductivity
Authors: Lu Ke , Gao Siyuan , Dick Robert J. , Sattar Zain , Cheng Yingwen
Published: February 2019

Hybrid Li anode in which Li metal is coated with thin layer of Mo6S8 particles has substantially improved surface stability and electrochemical activity.
Ni(ii)-doped anionic metal–organic framework nanowire arrays for enhancing the oxygen evolution reaction
Authors: Jiang Zhi-Qiang , Li Yu-Feng , Zhu Xue-Jun , Lu Jin , Wen Tian , Zhang Lei
Published: February 2019

An anionic metal–organic framework nanowire array not only directly grown on Cu foam but also successfully captured Ni2+ at ultra-small particles level, the resulting hybrid materials showed excellent electrocatalytic OER activities.
Plasmonic gold nanoparticles as multifaceted probe for tissue imaging
Authors: Cheng Yu-Hong , Tam Toby Siu-Chung , Chau Siu-Leung , Lai Samuel Kin-Man , Tang Ho-Wai , Lok Chun-Nam , Lam Ching-Wan , Ng Kwan-Ming
Published: February 2019

Gold nanoparticles as a sensitive probe for versatile tissue imaging techniques forming high quality chromogenic, fluorescence, and mass spectrometric images.
Rational synthesis of silver nanowires at an electrode interface by diffusion limitation
Authors: Liu Wei , Wang Kai , Zhou Yu , Guan Xiaoping , Che Ping , Han Yongsheng
Published: February 2019

We report an approach to synthesize silver nanowires by diffusion limitation.
The systematic influence of solvent on the conformational features of furanosides
Authors: Gaweda Karolina , Plazinski Wojciech
Published: February 2019

The conformational properties of furanosides are systematically affected by polar solvent which rearranges average partial atomic charges on ring atoms and shifts conformational equilibrium toward specific ring shapes.
Transformation synthesis of aluminosilicate SSZ-39 zeolite from ZSM-5 and beta zeolite
Authors: Xu Hao , Chen Wei , Wu Qinming , Lei Chi , Zhang Juan , Han Shichao , Zhang Ling , Zhu Qiuyan , Meng Xiangju , Dai Daniel , Maurer Stefan , Parvulescu Andrei-Nicolae , Müller Ulrich , Zhang Weiping , Yokoi Toshiyuki , Bao Xinhe , Marler Bernd , De Vos Dirk E. , Kolb Ute , Zheng Anmin , Xiao Feng-Shou
Published: February 2019

Aluminosilicate SSZ-39 zeolite has been prepared by transformation from ZSM-5 and beta zeolite in the presence of N,N-diethyl-cis-2,6-dimethylpiperidinium hydroxide.
Reply to the ‘Comment on “Bi-functional Li2B12H12 for energy storage and conversion applications: solid-state electrolyte and luminescent down-conversion dye”’ by M. Paskevicius, A. S. Jakobsen, M. Bregnhøj, B. R. S. Hansen, K. T. Møller, P. R. Ogilby and T. R. Jensen, J. Mater. Chem. A., 2019, DOI: 10.1039/c8ta10735a
Authors: Teprovich Joseph A. , Zidan Ragaiy
Published: February 2019

We reply to the comment raised by M. Paskevicius et al. on our paper characterizing the properties of the Li2B12H12.
The first identified heterozygous nonsense mutations in podocalyxin offer new perspectives on the biology of podocytopathies
Authors: Refaeli Ido , Hughes Michael R. , McNagny Kelly M.
Published: February 2019

In the last two decades, our understanding of the genetic underpinnings of inherited podocytopathies has advanced immensely. By sequencing the genomes of a large pool of families affected by focal segmental glomerulosclerosis (FSGS), researchers have identified a common theme: familial podocytopathies are frequently caused by genes selectively expressed in podocytes. Podocalyxin is a podocyte-specific surface sialomucin that has long been known to play important roles in podocyte morphogenesis and function. Few studies, however, have shown a conclusive link between mutations in the gene and FSGS complemented by functional evidence. In a fascinating new paper published in Clinical Science, Lin et al. identify two unrelated pedigrees in which dominant loss-of-function mutations in PODXL lead to adult-onset FSGS. Nonsense-mediated decay of the mutated PODXL transcripts leads to protein insufficiency, which in turn cause podocyte dysfunction through defects in motility and cytoskeletal organization. This is the first study to date that demonstrates, mechanistically, how autosomal dominant mutations in podocalyxin can lead to FSGS and renal insufficiency. Here, we summarize the experimental findings of this manuscript and propose, perhaps, a more controversial hypothesis: down-regulation of podocalyxin protein expression from podocytes is a critical turning point in the progression of most podocytopathies and may be mechanistically relevant to glomerulopathies in which podocyte damage is not necessarily induced by genetic lesions.
Eliciting Naturalistic Conversations: A Method for Assessing Communication Ability, Subjective Experience, and the Impacts of Noise and Hearing Impairment
Authors: Beechey Timothy , Buchholz Jörg M. , Keidser Gitte
Published: February 2019

Purpose

The purpose of this study was to introduce a method of eliciting conversational behavior with many aspects of realism, which may be used to study the impacts of hearing impairment and noise on verbal communication; to describe the characteristics of speech and language participants produced during the task; and to assess participants' engagement and motivation while completing the task.

Method

Twenty young adults with normal hearing and 20 older adults with hearing impairment took part in face-to-face conversations while completing a referential communication puzzle task designed to elicit natural conversational speech production and language with a number of realistic characteristics. Participants rated the difficulty and relevance of acoustic scenes for communication and their engagement in conversations.

Results

The communication task elicited speech production in a natural conversational register and language with many realistic characteristics, including complex linguistic constructions and typical disfluencies found in everyday speech, and approximately balanced contributions within dyads. Subjective ratings suggest that the task is robust to learning and fatigue effects and that participants remained highly engaged throughout the experiment. All participants were able to maintain successful communication regardless of background noise level and degree of hearing impairment.

Conclusions

The communication task described here may be used as part of a functional assessment of the ability to communicate in the presence of noise and hearing impairment. Although existing speech assessments have many strengths, they do not take into account the inherently interactive nature of spoken communication or the effects of motivation and engagement.
Knowledge Is Power: Improving Outcomes for Patients, Partners, and Professionals in the Digital Age
Authors: Ferguson Melanie , Maidment David , Henshaw Helen , Gomez Rachel
Published: February 2019

Purpose

The aim of this research was to develop and evaluate methods to address poor knowledge of hearing aids, hearing loss, and communication in patients, partners, and nonaudiologic health and social care professionals.

Method

An interactive multimedia educational program (C2Hear) has been co-produced with hearing aid users and audiologists to provide high-quality information and demonstrate complex concepts relating to hearing aids and communication.

Results

A randomized controlled trial showed numerous benefits for first-time hearing aid users that included better knowledge and skill, and increased hearing aid use and satisfaction. Patients reported that C2Hear was highly useful, enjoyable, and preferable to written information. C2Hear Online is now freely available on YouTube and has global reach, well in excess of 150,000 views. Further developments include a version for communication partners, which showed that joint-working between hearing aid users and their communication partners resulted in joint responsibility for communication that facilitated communication behaviors. In addition, a behavior theory-driven version for use with mobile technologies (m2Hear) has been designed to be tailored to the needs of individual hearing aid users. m2Hear includes more activities/interaction to maximize user engagement and learning. Finally, C2Hear has been used to improve hearing-related knowledge in other health and social care professionals, such as carehome assistants.

Conclusion

This range of educational programs and tools aims to improve knowledge and skills, leading to better outcomes for patients, partners, and health care professionals.
Generic Type 3 WT models: comparison between IEC and WECC approaches
Authors: Lorenzo‐Bonache Alberto , Honrubia‐Escribano Andres , Fortmann Jens , Gómez‐Lázaro Emilio
Published: February 2019

The widespread use of renewable energies around the world has generated the need for new tools and resources to allow them to be properly integrated into current power systems. Power system operators need new dynamic generic models of wind turbines and wind farms adaptable to any vendor topology and which permit transient stability analysis of their networks with the required accuracy. Under this framework, the International Electrotechnical Commission (IEC) and the Western Electricity Coordinating Council (WECC) have developed their own generic dynamic models of wind turbines for stability analysis. Although these entities work in conjunction, the focus of each is slightly different. The WECC models attempt to minimise the complexity and number of parameters needed, while the IEC approach aims to optimise comparison with real turbine measurements. This study presents a detailed comparison between these two different approaches for modeling a Type 3 (i.e., DFIG) wind turbine in MATLAB/Simulink. Finally, several simulations are conducted, with which the consequences of the different approaches are evaluated. The results of this paper are of interest to power system operators as well as wind turbine manufacturers who require further assistance in adapting their specific models to the simplified versions provided by the International Committees.
Recovering saturated images for high dynamic kernel-phase analysis
Authors: Laugier R. , Martinache F. , Ceau A. , Mary D. , N’Diaye M. , Beuzit J.-L.
Published: February 2019

Kernel-phase observables extracted from mid- to high-Strehl images are proving to be a powerful tool to probe within a few angular resolution elements of point sources. The attainable contrast is limited, however, by the dynamic range of the imaging sensors. The Fourier interpretation of images with pixels exposed beyond the saturation has so far been avoided. In cases where the image is dominated by the light of a point source, we show that we can use an interpolation to reconstruct the otherwise lost pixels with an accuracy sufficient to enable the extraction of kernel-phases from the patched image. We demonstrate the usability of our method by applying it to archive images of the Gl 494AB system taken with the Hubble Space Telescope in 1997. Using this new data point along with other resolved observations and radial velocity measurements, we produce improved constraints on the orbital parameters of the system, and consequently the masses of its components.
So close, so different: characterization of the K2-36 planetary system with HARPS-N
Authors: Damasso M. , Zeng L. , Malavolta L. , Mayo A. , Sozzetti A. , Mortier A. , Buchhave L. A. , Vanderburg A. , Lopez-Morales M. , Bonomo A. S. , Cameron A. C. , Coffinet A. , Figueira P. , Latham D. W. , Mayor M. , Molinari E. , Pepe F. , Phillips D. F. , Poretti E. , Rice K. , Udry S. , Watson C. A.
Published: February 2019

Context. K2-36 is a K dwarf orbited by two small (Rb = 1.43 ± 0.08 R⊕ and Rc = 3.2 ± 0.3 R⊕), close-in (ab = 0.022 au and ac = 0.054 au) transiting planets discovered by the Kepler/K2 space observatory. They are representatives of two distinct families of small planets (Rp < 4 R⊕) recently emerged from the analysis of Kepler data, with likely a different structure, composition and evolutionary pathways.

Aims. We revise the fundamental stellar parameters and the sizes of the planets, and provide the first measurement of their masses and bulk densities, which we use to infer their structure and composition.

Methods. We observed K2-36 with the HARPS-N spectrograph over ~3.5 yr, collecting 81 useful radial velocity measurements. The star is active, with evidence for increasing levels of magnetic activity during the observing time span. The radial velocity scatter is ~17 m s−1 due to the stellar activity contribution, which is much larger that the semi-amplitudes of the planetary signals. We tested different methods for mitigating the stellar activity contribution to the radial velocity time variations and measuring the planet masses with good precision.

Results. We find that K2-36 is likely a ~1 Gyr old system, and by treating the stellar activity through a Gaussian process regression, we measured the planet masses mb = 3.9 ± 1.1 M⊕ and mc = 7.8 ± 2.3 M⊕. The derived planet bulk densities ρb = 7.2−2.1+2.5 g cm−3 and ρc = 1.3−0.5+0.7 g cm−3 point out that K2-36 b has a rocky, Earth-like composition, and K2-36 c is a low-density sub-Neptune.

Conclusions. Composed of two planets with similar orbital separations but different densities, K2-36 represents an optimal laboratory for testing the role of the atmospheric escape in driving the evolution of close-in, low-mass planets after ~1 Gyr from their formation. Due to their similarities, we performed a preliminary comparative analysis between the systems K2-36 and Kepler-36, which we deem worthy of a more detailed investigation.
Analytical ray-tracing in planetary atmospheres
Authors: Bourgoin A. , Zannoni M. , Tortora P.
Published: February 2019

Context. Ground-based astro-geodetic observations and atmospheric radio occultations are two examples of observational techniques requiring a scrutiny analysis of atmospheric refraction. In both cases, the measured changes of the observables are geometrically related to changes in the photon path through the refractive profile of the crossed medium. Therefore, having a clear knowledge of how the refractivity governs the photon path evolution is of prime importance to clearly understand observational features.

Aims. We analytically performed the integration of the photon path and the light time of rays traveling across a non-spherically symmetric planetary atmosphere.

Methods. Assuming that the atmospheric refraction evolves linearly with the Newtonian potential, we derived an exact solution to the equations of geometrical optics. By varying the solution’s arbitrary constants of integration, we reformulated the equation of geometrical optics into a new set of osculating equations describing the constants’ evolution following any changes in the refractive profile. We have highlighted the capabilities of the formalism, carrying out five realistic applications in which we derived analytical expressions. Finally, we assessed the accuracy by comparing the solution to results from a numerical integration of the equations of geometrical optics in the presence of a quadrupolar moment (J2).

Results. Analytical expressions for the light time and the refractive bending are given with relative errors at the level of one part in 108 and one part in 105, for typical values of the refractivity and J2 at levels of 10−4 and 10−2, respectively.

Conclusions. The establishment of the osculating equations for the ray propagation has two main advantages. Firstly, it provides an easy and comprehensive geometrical picture for interpreting the photon path. Secondly, it allows the analytical solving of the ray propagation in the presence of non-radial dependencies in the refractive profile.
Effects of aluminum composites on the regression rates of solid fuels
Authors: Paravan C. , Penazzo S. , Dossi S. , Stocco M. , DeLuca L.T. , Galfetti L.
Published: February 2019

Innovative, mechanically activated Al–polytetrafluoroethylene (PTFE) composites and ammonium perchlorate (AP) coated nano-sized aluminum (C-ALEX) were produced, characterized, and tested as solid fuel additives. The ballistics of fuel formulations based on hydroxylterminated polybutadiene (HTPB) was investigated in a microburner by a time-resolved technique for regression rate (rf) data reduction. Both Al-composites show promising results in terms of rf and mass burning rate enhancement. In particular, the C-ALEX showed a percent rf increase over the baseline (HTPB) of 27% at an oxidizer mass flux of 350 kg/(m2s), without requiring dedicated dispersion procedures. This performance enhancement was nearly constant over the whole investigated range.
Analytical viscous flow model and test validation of a swirl injector for rocket engine application
Authors: Fiore G. , Bach C. , Sieder J. , Tajmar M.
Published: February 2019

The generally adopted flow model inside a swirl injector, widely used injection concept for propulsive applications, relies upon the hypothesis of ideal flow neglecting the fluid viscosity effects. This model showed significant prediction errors with relatively high viscosity propellants, often leading to the need of an experimental characterization of the injection elements. In this paper, an analytical approach is presented, which includes the effects of viscous diffusion on the injector performance leading to a close form flow solution. The built model is thus experimentally validated testing a liquid oxygen (LOx) and an ethanol injector: the good agreement between the model and the experimental results leads to the construction of the injectors operational maps describing the injector behavior even in the presence of viscous effects.
Large-eddy simulation of transcritical liquid oxygen/methane jet flames
Authors: Müller H. , Pfitzner M.
Published: February 2019

A numerical method to perform large-eddy simulations (LES) of nonpremixed liquid oxygen/methane (LOx/CH4) combustion at supercritical pressures is presented and the computational results are compared with available experimental data. The injection conditions of the considered test case resemble those in typical liquid-propellant rocket engines (LRE). Thermodynamic nonidealities are modeled using the Peng–Robinson (PR) equation of state (EoS) in conjunction with a novel volume-translation method to correct deficiencies in the transcritical regime. The resulting formulation is more accurate than the standard cubic EoS's without deteriorating their good computational efficiency. The real-gas thermodynamics model is coupled with the steady laminar flamelet model (SLFM) for turbulent nonpremixed combustion to incorporate chemical reactions at reasonable computational cost in the LES. A reduced reaction mechanism, which is validated with respect to the full mechanism, is used to generate a flamelet library. A comparison of the LES result with available OH* measurements shows that important flow features are well predicted.
Numerical investigation of an unsteady injection adapted to the continuous detonation wave rocket engine operation
Authors: Gaillard T. , Davidenko D. , Dupoirieux F.
Published: February 2019

Detonation applied to propulsion could result in a promising increase of the thermodynamic efficiency of the engine cycle. Numerical simulations of the detonation propagating in the Continuous Detonation Wave Rocket Engine (CDWRE) are currently performed but still do not account for realistic injection process. The assumption of an ideal injected premix is generally chosen for convenience to obtain theoretical results. Comparison of the numerical results with experiments is difficult because of the clear difference of the injection configurations. Some physical aspects of the separate injection of the components used in experiments are not clearly assessed. This study is included in a wider numerical project aimed at designing and optimizing a realistic CDWRE. The optimization process is presently focused on the injector. One element of the injection hole pattern is considered assuming that this element is periodically repeated over the injector head. The aim of the work presented here is to model and analyze the refill process of the components in the combustion chamber behind the rotating detonation. The simulation starts just after the passage of the detonation over the considered injection element. This simulation gives information on the way the injected propellants recreate the reactive mixture for the next detonation. In the first step, two-dimensional (2D) computations helped us to set up the methodology and to study the dynamic response of the fresh components injected. A comparison between 2D homogeneous and separate injections is provided. In the second step, three-dimensional (3D) computations have been performed with a separate injection suitable for the CDWRE operation. Some performance parameters are evaluated such as mixing efficiency or filling of the domain.
VINCI®, the european reference for ariane 6 upper stage cryogenic propulsive system
Authors: Alliot P. , Delange J.-F. , De Korver V. , Sannino J.-M. , Lekeux A. , Vieille B.
Published: February 2019

The intent of this publication is to provide an overview of the development of the VINCI® engine over the period 2014–2015. The VINCI® engine is an upper stage, cryogenic expander cycle engine. It combines the required features of this cycle, i. e., high performance chamber cooling and high performance hydrogen turbopump, with proven design concepts based on the accumulated experience from previous European cryogenic engines such as the HM7 and the VULCAIN®. In addition, its high performance and reliability, its restart and throttle capability offer potential applications on various future launcher upper stages as well as orbital spacecraft. At the end of 2014, the VINCI® successfully passed the Critical Design Review that was held after the major subsystem (combustion chamber, fuel and oxygen turbopump) had passed their own Critical Design Review all along the second half of 2014. In December, a Ministerial Conference at government level gave priority to the Ariane 6 program as Europe future launcher. In the framework of this decision, VINCI® was confirmed as the engine to equip Ariane 6 cryogenic upper stage engine. This publication shows how the VINCI development is progressing toward qualification, and also how the requirements of the new Ariane 6 configuration taken into account, i. e., offering new opportunities to the launch system and managing the new constraints. Moreover, the authors capitalize on the development already achieved for the evolution of Ariane 5. In parallel to completing the engine development and qualification, the configuration and the equipment of the propulsive system for Ariane 6 such as the components of the pressurization and helium command systems, board to ground coupling equipment, are being defined.
Delivering engine demonstrators for competitive evolutions of the european launchers
Authors: Caruana J.-N. , De Rosa M. , Kachler T. , Schoroth W. , Underhill K.
Published: February 2019

The year 2014 was one of achievements for the propulsion projects of the Future Launchers Preparatory Programme (FLPP). Highly relevant results were produced by hot-fire testing of three different engine demonstrators — a solid propulsion demonstrator focusing on pressure oscillations, a 5-kilonewton storable bipropellant engine, and a 25-kilonewton hybrid propulsion demonstrator. These concrete achievements were accompanied by the fast progress of a 115-kilonewton cryogenic expandercycle thrust chamber demonstrator which reached Preliminary Design Review (PDR) by end 2014, with hot-fire tests scheduled in 2017. These achievements give a solid grounding to the continuation and expansion of engine demonstrator projects at ESA Launchers.
A preliminary design study for an expander liquid oxygen turbopump
Authors: Maeding C. , Souverein L. , Hummel D. , Koenigbauer S. , Wagner A. , Alting J.
Published: February 2019

In the recent years, Airbus DS GmbH started a turbopump initiative to buildup fundamental capabilities in analyzing and designing turbomachinery within a German national funded program “TARES.” Turbomachinery is widely used in different rocket propulsion systems and include such parts as pumps and turbines. Turbines are used for generating power required by pumps in order to feed the propellants to the thrust chamber. The paper is dedicated to present an overview about currently ongoing conceptual design activities of turbomachinery covering the main design phases like TPA (TurboPump Assembly) layout tradeoff; rotational speed selection with respect to efficiency and cavitation; flow path design techniques including blade profiling; computer-aided design (CAD) work; and preliminary structural analyses. This paper presents the main outcome applying the established design logic to a liquid oxygen (LOx) turbomachinery. The component is designed based on a dedicated specification for an expander cycle type engine. This includes a LOx pump unit comprising inducer and impeller as well as a subsonic single stage reaction turbine. For the turbine drive, gaseous hydrogen (GH2) heated within the thrust chamber cooling circuit is used. Within this paper, a general overview about the preliminary work results of pump and turbine sizing, profiling, performance estimation as well as structural aspects is given.
Analytical models of unstable rarefied gas flow in channels and nozzles: simulation and comparison
Authors: Aksenova O.A. , Khalidov I.A.
Published: February 2019

Three different analytical models of unstable rarefied gas flows in channels and nozzles are compared using numerical simulations by MonteCarlo method. Numerical results have demonstrated the chaotic behavior of constructed nonlinear dynamic system and the limit properties of corresponding trajectories, attractors, and bifurcations of rarefied gas flows in channels. Flow conditions satisfying the experimental requirements are indicated where the instability of considered type can be detected. The advantages and the drawbacks of the considered approximations are detected and the features of obtained solutions are indicated. Recommendations are given for applying the results in practical applications and in numerical calculations of rarefied gas flows.
Quasi-two-dimensional approximation for numerical simulation of flows in engine ducts
Authors: Vlasenko V. , Shiryaeva A.
Published: February 2019

New quasi-two-dimensional (2.5D) approach to description of three-dimensional (3D) flows in ducts is proposed. It generalizes quasi-one-dimensional (quasi-1D, 1.5D) theories. Calculations are performed in the (x; y) plane, but variable width of duct in the z direction is taken into account. Derivation of 2.5D approximation equations is given. Tests for verification of 2.5D calculations are proposed. Parametrical 2.5D calculations of flow with hydrogen combustion in an elliptical combustor of a high-speed aircraft, investigated within HEXAFLY-INT international project, are described. Optimal scheme of fuel injection is found and explained. For one regime, 2.5D and 3D calculations are compared. The new approach is recommended for use during preliminary design of combustion chambers.
Experimental investigation of the effect of the air inlet angle and the combustion pressure in a ducted rocket combustor
Authors: Laguzzi V. , Molinaro F. , Natan B.
Published: February 2019

The scope of the study is to evaluate the combustion efficiency of a ducted rocket combustor operating at different conditions, using a connected-pipe testing setup. An experimental parametric investigation was conducted to evaluate the effect of the inlet air-injection angles and the effect of the combustion pressure for different fuel-to-air ratios. The experimental results indicate that best energetic performance was obtained for an injection angle of 120°, i. e., against the main flow direction. The reason is that this way better mixing was obtained and the residence time increased. Characteristic velocity was found to decrease with decreasing the combustion pressure.
Simulation and structural optimization of 3d Timoshenko beam networks based on fully analytic network solutions
Authors: Kufner Tobias , Leugering Günter , Semmler Johannes , Sting Michael , Strohmeyer Christoph
Published: February 2019

This article is concerned with the efficient and accurate simulation and optimization of linear Timoshenko beam networks subjected to external loads. A solution scheme based on analytic ansatz-functions known to provide analytic solutions for the deformation and rotation of a single beam with given boundary data is extended to the full network. It is demonstrated that the analytic approach is equivalent to a finite element (FE) method where only one element with a suitably chosen shape function per beam is required. The solution of the FE-type system provides analytic solutions at the nodes, from which the solutions along the beams can be reconstructed. Consequently analytic solutions for the network can be computed by a numerical scheme without applying a spacial discretization. While the assembly of the local stiffness matrices is slightly more expensive compared to an FE model using, e.g., linear ansatz-functions, the complexity of the solution of the FE-system is not. This is particularly interesting for topology and material optimization problems formulated on the network. In order to demonstrate the efficiency of the approach a numerical comparison to the case of linear ansatz-functions is provided followed by a series of studies with topology and multi-material optimization problems on networks.
Investigation of the effect of turbulence intensity and nozzle exit boundary layer thickness on stability pattern of subsonic jet
Authors: Gohardehi Siavash , Arablu Saeed , Afshin Hossein , Farhanieh Bijan
Published: February 2019

In this study, factors affecting the noise generation by instability waves in a subsonic jet with acoustic Mach number of 0.5 are investigated using linear stability analysis. The base flow required for instability analysis is obtained by modeling the jet stream based on the k-ε turbulence model and using the empirical coefficients suggested by Thies and Tam [1]. The resulting base flow profiles are used to solve the linear instability equation, which governs the pressure perturbation for obtaining the eigenvalues and eigenfunctions. The results of linear instability analysis for phase and amplitude of pressure fluctuations are compared against the existing experimental data, which demonstrated the validity of the conducted instability analysis. The effects of turbulence intensity and thickness of the boundary layer at the jet nozzle exit on the results of the linear instability analysis are investigated. The results show that as the turbulence intensity at nozzle exit increases, the frequency range for which the spatial growth rates are positive grows smaller, and except for very low frequencies, this leads to decreased growth rates in both axisymmetric and first azimuthal modes. Also, in both of these modes, an increase in the thickness of the boundary layer at nozzle exit leads to a decrease in perturbation's growth rates in the surveyed frequency ranges.
Linearity investigation from a vibratory fatigue bench
Authors: Gautrelet Christophe , Khalij Leila , Appert Aymeric , Serra Roger
Published: February 2019

High-cycle fatigue behaviour of structures can be obtained through vibratory tests using frequency response functions or transmissibilities. To this end, this study deals with the qualification of the vibratory fatigue bench developed at the Laboratory of Mechanic of Normandy. This bench uses an electrodynamic shaker which can reach excitation frequencies that are higher than conventional fatigue machines. To carry out relevant tests, the capacities of the test bench must be well known. Correlations between excitation and response were investigated to determine the allowable setpoints to maintain linearity between the input and output signals to validate our system. The difficulties related to the experiments were presented and discussed.
Fault detection of damper in railway vehicle suspension based on the cross-correlation analysis of bogie accelerations
Authors: Dumitriu Mădălina
Published: February 2019

Nowadays, the condition-based maintenance is associated more and more with railway transport to improve the safety, availability, reliability and capacity of this transport system, and to reduce life cycle costs for the railway vehicles. The condition-based maintenance requires that vehicle components are replaced based on their real condition, which implies the fault detection and isolation during the train's operation. The paper proposes a method to detect the failure of the damper in the primary suspension of the rail vehicle, based on the analysis of cross-correlation of the vertical accelerations measured on the bogie frame against the two axles. The numerical simulations and experimental results show a very good correlation between the bogie accelerations when the dampers are in a normal operation condition. This thing is shown based on the values of the cross-correlation coefficient (CCC) of the bogie accelerations. The failure in a damper can be detected by the decrease of the CCC of the bogie accelerations, a confirmed fact in the results derived from numerical simulations. The proposed method has more advantages, namely, it is a signal-based method and hence does not require a complex mathematical modelling of the vehicle-track system and knowledge of its parameters or of the external conditions; the method makes relative comparisons between measurements and hence reduces the effect of the factors that influence outputs; the method can be also extended for the secondary suspension; the method can be easily implemented on any type of bogie.
Influence of water flow rate in mold on hooks and inclusions at the subsurface of ultra low carbon Al-killed continuous casting slabs
Authors: Zhang Lifeng , Zhang Xubin , Ren Ying , Yang Wen
Published: February 2019

The influence of water flow rate on the surface cleanliness of slabs was investigated through the hook reveal and inclusion detection. The numerical simulation was performed to calculate the shell thickness with different water flow rate. With the decrease of the water flow rate from 99 to 88 L/s, the hook depth reduced at most of positions, and the number of > 5 μm inclusions decreased. The contour was calculated to provide guidance for adjustment of the water flow rate.
Augmented Reality in der Augenheilkunde: Technische Innovation ergänzt studentische Lehre
Authors: Loidl Max , Schneider Achim , Keis Oliver , Öchsner Wolfgang , Grab-Kroll Claudia , Lang Gerhard K. , Kampmeier Jürgen
Published: February 2019

Hintergrund An der Medizinischen Fakultät der Universität Ulm werden die Lernziele der Augenheilkunde den Studierenden schwerpunktmäßig in einer einwöchigen Blockveranstaltung im 4. Studienjahr vermittelt. Gemäß des Nationalen Kompetenzbasierten Lernzielkatalogs Medizin (NKLM) zählt zu diesen Lernzielen auch die klinische Untersuchung des Auges inklusive der Augenhintergrunduntersuchung. Um diese im NKLM definierte Kompetenz bestmöglich zu trainieren, wurde an der Augenklinik der Universität Ulm ein neuartiger, auf „Augmented Reality“ basierender Trainingssimulator (Eyesi Indirect, VRmagic Holding AG, Mannheim) in die Lehre integriert. Im Rahmen der durchgeführten Blockwoche wurden 2 Kernfragen untersucht: Steigert der einwöchige Blockunterricht das Interesse für das Fachgebiet Augenheilkunde? Wie beurteilen Studierende dabei den Einsatz einer innovativen E-Learning-Technologie verglichen mit 3 anderen klassischen Lehrmethoden zum Erlernen der Ophthalmoskopie?

Material/Methoden Im Rahmen der studentischen Lehre (Blockwochen Juli und Oktober 2016) wurden 292 Studierende per Fragebogen jeweils am Anfang und am Ende der einwöchigen Veranstaltung anonym und auf freiwilliger Basis bezüglich ihrer Einschätzung der Blockwoche und des Trainingssimulators befragt. Die Ophthalmoskopien wurden klassisch am Ophthalmoskop-Trainer, am Kopfmodell und an Kommilitonen geübt und anschließend am neuen Simulator durchgeführt.

Ergebnisse Insgesamt zeigte sich bei den Studierenden ein nur geringes Interesse für das Fachgebiet Augenheilkunde. Die Blockwoche konnte jedoch dazu beitragen, das Interesse zu steigern (p < 0,001). Auch die Attraktivitätseinschätzungen vor und nach der Blockwoche bezüglich der Augenheilkunde als späteres Berufsziel und als Wahlfach im Praktischen Jahr ließen sich signifikant steigern (p < 0,001 bzw. p = 0,031). Hinsichtlich des Einsatzes innovativer E-Learning-Technologien konnte gezeigt werden, dass der Umgang mit dem Simulator zum Erlernen der Ophthalmoskopie von den Studierenden attraktiver eingeschätzt wurde als die klassischen technikgestützten Lehrmethoden (alle p < 0,01). Die Freude am Lernen konnte tendenziell nur durch das Üben am Kommilitonen weiter gesteigert werden (p = 0,051).

Schlussfolgerung Die Ergebnisse der vorliegenden Untersuchung zeigen eine positive Auswirkung der Blockwoche auf die Attraktivitätseinschätzung des Fachgebiets durch die teilnehmenden Studierenden. E-Learning-Methoden können die Freude am Lernen steigern. Einen vollständigen Ersatz der Übungen am realen Menschen kann der Trainingssimulator allerdings nicht liefern.
Wenn gehörlose Kinder hörend werden – Auswirkungen der
CI-Versorgung von gehörlosen Kindern gehörloser Eltern auf deren
Familiensituation
Authors: Leonhardt Annette
Published: February 2019

1993 wurden erstmalig gehörlose Kinder von gehörlosen Eltern mit CI versorgt. Die
Situation dieser Kinder und ihrer Eltern ist immer wieder Gegenstand von
Forschungen des seit 2000 bestehenden Münchner Forschungsprogramms „Gehörlose
Eltern und Kinder mit CI“. Zu diesem gehört die Teilstudie „Familiensituation
von gehörlosen Eltern mit CI-Kindern“. Eines der Ergebnisse dieser Studie ist,
dass die implantierten Kinder die Rolle von Codas übernehmen. Das zeigt sich
insbesondere in der Übernahme von Dolmetschleistungen für die Eltern.