bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of heat transfer and its effect on solidification in water cooled LPDC of wheels
Authors: Saadah AU , Reilly C , Maijer DM , Cockcroft SL 
Published: May 2019

Abstract
Computational process modelling has become an important engineering tool in the casting industry to predict the solidification sequence in complex castings. Used properly, this tool can help reduce manufacturing costs. One of the challenging issues in developing casting simulations of the low pressure die casting (LPDC) process for automotive wheels is to quantify the heat transfer coefficients (HTC) within the cooling channels in a die. When water is used as the cooling media, the HTCs exhibit a complex, non-linear behaviour due to the boiling phenomena that occur making it possible to extract a significant amount of heat from the die in a short period of time and influence the solidification of a wheel. Primarily, constant heat transfer coefficients have been used to describe this heat transfer in casting models up until now, but an opportunity exists to improve the transient description of heat transfer in channels cooled with water. In this paper, HTC’s in a lab-scale physical analogue model of die cooling will be characterized as a function of initial die temperatures.
Interfaces at internal chills in solidifying steel sections
Authors: Monroe Charles , Foley Robin , Griffin John , Gibbons Sean , Saville Alec 
Published: May 2019

Abstract
Chills are used in the production of metal castings as a thermal aid to promote directional solidification in casted sections. This study will review microstructure and thermal circumstances of the internal chill interface where the chill is intended to be incorporated into the structure of the cast section. The conditions for interface coherency of cast steel sections from 25 to 50mm will be shown. Solidification proceeds away from the interface chill growing to a maximum thickness and then melting back to the original chill geometry. Furthermore, it is shown that promoting section solidification prior to the complete melting of the internal chill can lead to the formation of interfaces will be coherent across the chill and cast sections for compatible steel alloys. A computer model of the heat transfer and interface evolution show the possibility of using the coherent interface of internal chills in the design of other cast components.
Effect of cooling rate on the porosity defect in the thick aluminum casting by 3D computed tomography analysis
Authors: Cho I S , Kwak S Y , Kim Y H , Lee H K , Yoo S M 
Published: May 2019

Abstract
In the present study, effect of cooling rate on the formation of the porosity in the thick aluminum sand casting was investigated. Nowadays large scale thick aluminum casting replaces steel frame for vacuum chamber for semiconductor production, with the consideration of weight and cost reduction. Several thick aluminum castings were manufactured using chill with temperature measurements. The castings were inspected by using 3D computed tomography in order to quantify the porosity defect density in the castings. Effect of the thickness of the chill on the porosity defect density were discussed.
A Novel Powder Metallurgy Technique for Introducing Synthetic Inclusions into Liquid Steel
Authors: Smith A , Tran T , Ji F , Tiekink W , Abbel G , Verdier S 
Published: May 2019

Abstract
Previous studies have shown that it is extremely problematic to add synthetic inclusions successfully into liquid steel for clean steel experiments. Small micro-particles encapsulated in a metallic parcel are difficult to pass through the melt-gas interface and inclusions tend to agglomerate then float up to the liquid surface. In this study, powder metallurgy is used to distribute cerium oxide particles of a known size from 1µm to 14µm within a small-scale steel ingot. Carbonyl iron powder has been mixed with 0.1 wt.% cerium oxide (CeO2) then sintered in an electrical furnace to produce sintered ingots of 500 grams. A series of induction furnace melting trials using a total of 400 grams of electrolytic iron and cerium oxide sintered ingot have been undertaken. The work has included extensive FE-SEM analysis using the INCA Feature® to characterise synthetic cerium oxide inclusions from both the sintered ingots and trial ingots. The INCA Feature® results showed that the size distribution and number of cerium oxide inclusions agreed well between the sintered ingot and trial ingot. The synthetic cerium oxide inclusions are homogeneously dispersed through the bottom, centre and top of the trial ingot with approximately 16 number counts/mm2. Analysis suggests that more than 95% of the cerium oxide from the sintered ingot has been distributed throughout the trial ingot. The work has also been upscaled from 400 grams up to 1.5 kg and has been successful. The method developed will be useful for further studies into steel cleanness of high value alloyed steels.
Study of elasto-plastic deformation in a cast AlCu7 alloy
Authors: Schöbel M , Fernández R , Degischer HP 
Published: May 2019

Abstract
The need for efficient and clean solutions, due to the increasing current environmental regulations puts extra pressure on new combustion engine development, to compete in a market with alternative driving concepts. Downsizing and weight reduction can reduce the engine emission and efficiency, but require light alloys with superior thermo-mechanical properties for high temperature exposure to maintain the same engine performance. Cast Al-Cu could be alternative to standard Al-Si alloys for new engine generations due to their higher temperature strength, creep-resistance and long term stability of engine components. In Al-Si and Al-Cu cast alloys with heterogeneous microstructures a composite-like deformation behavior is responsible for superior high temperature properties. Stiff Si or Al2Cu particles, respectively reinforce a ductile α-Al matrix to a composite with improved thermo-mechanical strength. However, different Young’s moduli and coefficients of thermal expansion are responsible for micro stress gradients and unpredictable micro crack formation under operation. These micro-mechanical deformation mechanisms in Al-Si and Al-Cu systems, responsible for crack initiation and growth, have been scarcely investigated so far.
This manuscript describes an example of elasto-plastic deformation mechanisms in an AlCu7 alloy. Tensile testing shows anomalous macroscopic deformation behavior indicating unknown internal micro-mechanical processes. External loading until yield strength and beyond are applied under laboratory conditions and during in-situ neutron diffraction. The results of macroscopic deformation and micro strain evolution are compared and correlated with the heterogeneous micro structure. High resolution synchrotron computed tomography reveals conclusions on the micro-mechanic deformation mechanisms and their effects on the macroscopic damage initiation and material’s service performance.
On the use of heterogeneous thermomechanical and thermophysical material properties in finite element analyses of cast components
Authors: Jansson Johan , Olofsson Jakob , Salomonsson Kent 
Published: May 2019

Abstract
Cast components generally show a heterogeneous distribution of material properties, caused by variations in the microstructure that forms during solidification. Variations caused by the casting process are not commonly considered in structural analyses, which might result in manufacturing of sub-optimised components with unexpected in-use behaviour. In this paper, we present a methodology which can be used to consider both thermomechanical and thermophysical variations using finite element analyses in cast components. The methodology is based on process simulations including microstructure modelling and correlations between microstructural features and material properties. Local material data are generated from the process simulation results, which are integrated into subsequent structural analyses. In order to demonstrate the methodology, it is applied to a cast iron cylinder head. The heterogeneous distribution of material properties in this component is investigated using experimental methods, demonstrating local variations in both mechanical and physical behaviour. In addition, the strength-differential effect on tensile and compressive behaviour of cast iron is considered in the modelling. The integrated simulation methodology presented in this work is relevant to both design engineers, production engineers as well as material scientists, in order to study and better understand how local variations in microstructure might influence the performance and behaviour of cast components under in-use conditions.
An investigation of the chill-casting interface dynamics in production of sand-cast A319 engine blocks
Authors: Farhang Mehr Farzaneh , Cockcroft Steve , Maijer Daan 
Published: May 2019

Abstract
In recent years, the automotive industry has been increasing the production of small, high-power gas engines as part of several strategies to achieve the new “Corporate Average Fuel Economy” (CAFE) standards. This trend requires an improvement in the thermal and mechanical fatigue durability of the aluminium alloys used in the production of the cylinder blocks in these engines. Conventionally, solid chills are employed in areas of these castings subject to high cyclic loading to enhance the mechanical performance of the cast material – i.e. in the main bearing bulkhead. A potential means of improving the efficacy of these chills is to incorporate water cooling. To assess the effectiveness of this method, a water-cooled chill was designed and installed in a bonded-sand engine block mould package (1/4 section). The moulds were instrumented with thermocouples, to measure the evolution of temperature at key locations in the casting, and “Linear Variable Displacement Transducers” (LVDTs), to measure the gap formation at the interface between the chill and the casting. This paper summarizes, at a high level, some of the findings of this work.
Nanofiber scaffolds attenuate collagen synthesis of human dermal fibroblasts through TGF-β1/TSG-6 pathway*
Authors: Xie Bei , Zhu Wanzong , Ding Pinghui , Chen Mengting , Li Ji , Lei Lei , Zhang Can , Nie Hemin 
Published: May 2019

Abstract
Nanofiber scaffolds are promising patches for skin tissue regeneration as they provide favorable environment for the adhesion, infiltration and proliferation of skin dermal fibroblasts. However, the effects of nanofiber scaffolds on scar formation remain to be elucidated. The aim of this study was to find out the relationship between nanofiber scaffolds and scar formation, along with the underlying mechanism. We found that polycaprolactone (PCL)/gelatin nanofiber scaffolds attenuated the mRNA expression of fibrosis-associated genes in fibroblasts, including collagen I (collagen type I alpha 1), collagen III (collagen type III alpha 1) and fibronectin. Specifically thicker scaffolds displayed stronger fibrosis inhibitory effect than thin scaffolds. The mechanism relied on TGF-β1/TSG-6 pathway, and overexpression of TSG-6 impaired the anti-fibrosis effect of nanofiber scaffolds, which decreased TGF-β1 expression with thickness-dependency. Moreover, in vivo study demonstrated that nanofiber scaffolds remarkably accelerated the wound healing process by reducing the ratios of collagen I/collagen III and TGF-β1, eventually decreased the deposition of collagens. Taken together, our results suggested that the attenuation of fibrosis by PCL/gelatin nanofiber scaffolds was TGF-β1-dependent and through TGF-β1/TSG-6 pathway. Nanofiber scaffold of appropriate thickness would accelerate skin wound healing, stimulate re-epithelialization and form cutaneous skin appendages in skin trauma. Thus, PCL/gelatin nanofiber scaffolds could be adopted for scar-free skin wound healing and skin cosmetics applications.
Absolute requirement for polyamines for growth of Escherichia coli mutants (mnmE/G) defective in modification of the wobble anticodon of transfer-RNA
Authors: Keller Christopher , Chattopadhyay Manas , Tabor Herbert 
Published: May 2019

Abstract
The genes mnmE and mnmG are responsible for the modification of uridine 34, ‘the wobble position’ of many aminoacyl-tRNAs. Deletion of these genes affects the strength of the codon-anticodon interactions of the aminoacyl-tRNAs with the mRNAs and the ribosomes. However, deletion of these genes does not usually have a significant effect on the growth rate of the standard Escherichia coli strains. In contrast, we have found that if the host E. coli strain is deficient in the synthesis of polyamines, deletion of the mnmE or mnmG gene results in complete inhibition of growth unless the medium contains polyamines. The finding of an absolute requirement for polyamines in our current work will be significant in studies on polyamine function, in studies on the function of the mnmE/G genes, and in studies on the role of aminoacyl-tRNAs in protein biosynthesis.
The quest for osmosensors in plants
Authors: Nongpiur Ramsong Chantre , Singla-Pareek Sneh Lata , Pareek Ashwani 
Published: May 2019

AbstractOsmotic stress has severe effects on crop productivity. Since climate change is predicted to exacerbate this problem, the development of new crops that are tolerant to osmotic stresses, especially drought and salinity stress, is required. However, only limited success has been achieved to date, primarily because of the lack of a clear understanding of the mechanisms that facilitate osmosensing. Here, we discuss the potential mechanisms of osmosensing in plants. We highlight the roles of proteins such as receptor-like kinases, which sense stress-induced cell wall damage, mechanosensitive calcium channels, which initiate a calcium-induced stress response, and phospholipase C, a membrane-bound enzyme that is integral to osmotic stress perception. We also discuss the roles of aquaporins and membrane-bound histidine kinases, which could potentially detect changes in extracellular osmolarity in plants, as they do in prokaryotes and lower eukaryotes. These putative osmosensors have the potential to serve as master regulators of the osmotic stress response in plants and could prove to be useful targets for the selection of osmotic stress-tolerant crops.
Sustaining Nursing Grand Rounds Through Interdisciplinary Teamwork and Interorganizational Partnership
Authors: Salinas Dagoberto , Johnson Stephen Christopher , Conrardy Julie Anne , Adams Tuesday Lynn , Brown James Denning 
Published: May 2019

In 2017, Navy Nurse Corps executives launched a new nursing professional practice model that promotes operational readiness, professional development, and transformational leadership. This directive prompted nursing leadership at Naval Hospital Jacksonville (NH JAX) to conduct a needs assessment survey to determine what kind of educational initiative nursing staff members would most welcome in support of the goals of the new practice model. Survey respondents favored case studies presented in a nursing grand rounds format. Our change implementation team designed and executed the grand rounds program, offering lunchtime presentations every other month. Topics included a wide range of “high-risk/low-volume” procedures—those infrequently performed at participants’ clinical sites. Ten months after the initiation of grand rounds, surveys were distributed to NH JAX participants to assess their perceptions of the value of the sessions in terms of professional development, interdisciplinary teamwork, and strengthened institutional partnerships.
Of the 161 nursing grand rounds participants, 41 (25%) responded to the postimplementation survey. Responses indicated that participants valued nursing grand rounds in enhancing clinical knowledge (83% agreed), discussing research and evidence-based practices (71% agreed), supporting professional development (88% agreed), improving interdisciplinary teamwork (83% agreed), and solidifying interorganizational partnerships (73% agreed). This article presents the implementation of the NH JAX grand rounds program and demonstrates how nursing grand rounds can serve as an excellent forum in which to develop knowledge, showcase research and evidence-based practices, support professional growth, improve collaboration, and strengthen partnerships.
Modulation of emotion perception and memory via sub-threshold amygdala stimulation in humans
Authors: Bujarski Krzysztof A. , Song Yinchen , Kolankiewicz Sophia I. , Wozniak Gabriella H. , Andrews Angeline S. , Guillory Sean A. , Roberts Dave W. , Aronson Joshua P. , Jobst Barbara C. 
Published: May 2019

AbstractA common human experience is noticing that emotional life events are more vividly remembered than dull ones. Studies show that the amygdala plays a central role in such emotionally driven enhancement of memory. With this in mind, we investigated the effect of electrical brain stimulation of the left human amygdala on performance on an emotional perception and emotional memory task. We randomly applied sub-threshold 50 Hz stimulation to the left amygdala in 10 patients (5 female and 5 male) with intracranial electrodes during the encoding portion of an emotional valence perception and emotional memory task. We found that amygdala stimulation did not affect reported valence for neutral stimuli (non-stimulated group average valence 5.34, stimulated 5.38, p=0.68) but it did affect positively (non-stimulated group average valence 7.31, stimulated 6.70, p=0.004) and negatively (non-stimulated group average valence 2.79, stimulated 3.55, p=0.0002) valenced stimuli in effect reporting both valence categories as more neutral. Furthermore, we found that stimulation did not significantly disrupt memory for neutral stimuli (68% vs. 61% correctly remembered p=0.48) or positive stimuli (87% vs. 70% correct, trend towards significant difference p=0.09) but did for negative stimuli (83% vs. 67% correct, p=0.03). These results suggest that electrical brain stimulation by our parameters likely reversibly inhibits amygdala function disrupting neural networks responsible for emotional perception and memory. This effect may have clinical implications in treatment of certain neuropsychiatric disorders, such as emotional dysregulation and post-traumatic stress disorder.Statement of significanceThe current study builds and expands on extensive prior research into the function of the human amygdala. It provides the first systematic description in humans of a cognitive change brought about by direct electrical stimulation of the amygdala on perception of emotional valence and emotional memory. The results provide further evidence on the importance of the amygdala in human cognition. Likewise, out method utilized to study the function of the amygdala can be extended to study the function of other brain regions in humans, such as the cingulate. While these results are preliminary and need to be duplicated, we aim to further study the effects of amygdala stimulation on emotional processing including possible therapeutic application for diverse group of neuropsychiatric conditions.
An Inordinate Fondness for Species with Intermediate Dispersal Abilities
Authors: Ashby Ben , Shaw Allison K. , Kokko Hanna 
Published: May 2019

AbstractJBS Haldane is widely quoted to have quipped that the Creator, if one exists, has an inordinate fondness for beetles. Although Coleoptera may not be the most speciose order once Hymenopteran diversity is fully accounted for, as a whole the very clear differences in species diversity among taxa require an explanation. Here we show both analytically and through stochastic simulations that dispersal has eco-evolutionary effects that predict taxa to become particularly species-rich when dispersal is neither too low nor too high. Our models combine recent advances in understanding coexistence in niche space with previously verbally expressed ideas, where too low dispersal imposes biogeographic constraints that prevent a lineage from finding new areas to colonize (reducing opportunities for speciation), while too high dispersal impedes population divergence, leading to few but widely distributed species. We show that this logic holds for species richness and is robust to a variety of model assumptions, but peak diversification rate is instead predicted to increase with dispersal. Our work unifies findings of increasing and decreasing effects of dispersal rate on speciation, and explains why organisms with moderate dispersal abilities have the best prospects for high global species richness.
Sleep, regional grey matter volumes, and psychological functioning in adolescents
Authors: Lapidaire Winok , Urrila Anna S. , Artiges Eric , Miranda Ruben , Vulser Hélène , Bézivin-Frere Pauline , Lemaître Hervé , Penttilä Jani , Banaschewski Tobias , Bokde Arun L.W. , Bromberg Uli , Büchel Christian , Conrod Patricia J. , Desrivières Sylvane , Frouin Vincent , Gallinat Jürgen , Garavan Hugh , Gowland Penny , Heinz Andreas , Ittermann Bernd , Papadopoulos-Orfanos Dimitri , Paus Tomáš , Smolka Michael N. , Schumann Gunter , Paillère Martinot Marie-Laure , Martinot Jean-Luc 
Published: May 2019

AbstractChanging sleep rhythms in adolescents often lead to sleep deficits and increased variability in sleep schedules. The adolescent brain, and in particular the rapidly developing structures involved in emotional control, are vulnerable to external and internal factors. In our previous study in adolescents at age 14, we observed a strong relationship between weekend sleep schedules and regional medial prefrontal cortex grey matter volumes. Here, we aimed to assess whether this relationship remained in this group of adolescents of the general population at the age of 16 (n=101; mean age 16.8 years; 55% girls). We further examined grey matter volumes in the hippocampi and the amygdalae, calculated with voxel-based morphometry. In addition, we investigated the relationship between regional grey matter volumes with psychological functioning. Sleep was assessed with self-reports and psychological functioning with the Strengths and Difficulties Questionnaire and tests on working memory and impulsivity. Later weekend wake-up times were associated with smaller grey matter volumes in the medial prefrontal cortex and the amygdalae, and greater weekend delays in wake-up time were associated with smaller grey matter volumes in the right hippocampus and amygdala. The medial prefrontal cortex region mediated the correlation between weekend wake up time and both externalising and internalising symptoms. Paying attention to regular sleep habits during adolescence could act as a protective factor against the emergence of psychopathology via enabling favourable brain development.
PP2ACdc55dephosphorylates Pds1 to inhibit spindle elongation
Authors: Khondker Shoily , Kajjo Sam , Chandler-Brown Devon , Skotheim Jan , Rudner Adam , Ikui Amy 
Published: May 2019

AbstractDNA replication stress stalls replication forks leading to chromosome breakage and Intra-S checkpoint activation. InS. cerevisiae, this checkpoint arrests the cell cycle by stabilizing securin (Pds1) and inhibiting the cyclin dependent kinase (CDK) through multiple pathways. Pds1 inhibits separase (Esp1) which cleaves the cohesin subunit Scc1 and also functions in spindle elongation. However, the role of Pds1-Esp1 in spindle elongation during replication stress response is unknown. Here, we show that Pds1 phosphorylation plays a positive role in spindle elongation through the Pds1-Esp1 interaction in unperturbed and replication stress conditions. PP2ACdc55directly dephosphorylates Pds1 bothin vivoandin vitro. Pds1 hyperphosphorylation in acdc55Δmutant enhanced the Pds1-Esp1 interaction, which accelerated spindle elongation. This PP2ACdc55-dependent Pds1 dephosphorylation plays a role during replication stress and acts independently of the known Mec1, Swe1 or Spindle Assembly Checkpoint (SAC) checkpoint pathways. We propose a model where PP2ACdc55dephosphorylates Pds1 to disrupt the Pds1-Esp1 interaction that inhibits spindle elongation during replication stress.