bluuebunny/crossref_metadata_2025 huggingface dataset:
IMAGING OBSERVATIONS OF THE HYDROGEN COMA OF COMET 67P/CHURYUMOV–GERASIMENKO IN 2015 SEPTEMBER BY THE PROCYON/LAICA
Authors: Shinnaka Yoshiharu , Fougere Nicolas , Kawakita Hideyo , Kameda Shingo , Combi Michael R. , Ikezawa Shota , Seki Ayana , Kuwabara Masaki , Sato Masaki , Taguchi Makoto , Yoshikawa Ichiro
Published: January 2017

The water production rate of a comet is one of the fundamental parameters necessary to understand cometary activity when a comet approaches the Sun within 2.5 au, because water is the most abundant icy material in the cometary nucleus. Wide-field imaging observations of the hydrogen Lyα emission in comet 67P/Churyumov–Gerasimenko were performed by the Lyman Alpha Imaging Camera (LAICA) on board the 50 kg class micro spacecraft, the Proximate Object Close Flyby with Optical Navigation (PROCYON), on UT 2015 September 7.40, 12.37, and 13.17 (corresponding to 25.31, 30.28, and 31.08 days after the perihelion passage of the comet, respectively). We derive the water production rates,

, of the comet from Lyα images of the comet by using a 2D axi-symmetric Direct Simulation Monte-Carlo model of the atomic hydrogen coma; (1.46 ± 0.47) × 1028, (1.24 ± 0.40) × 1028, and (1.30 ± 0.42) × 1028 molecules s−1 on 7.40, 12.37, and 13.17 September, respectively. These values are comparable to the values from in situ measurements by the Rosetta instruments in the 2015 apparition and the ground-based and space observations during the past apparitions. The comet did not show significant secular change in average water production rates just after the perihelion passage for the apparitions from 1982 to 2015. We emphasize that the measurements of absolute

based on the wide field of view (e.g., by the LAICA/PROCYON) are so important to judge the soundness of the coma models used to infer

based on in situ measurements by spacecraft, like the Rosetta.
What is the Mass of a Gap-opening Planet?
Authors: Dong (董若冰) Ruobing , Fung (馮澤之) Jeffrey
Published: January 2017

High-contrast imaging instruments such as GPI and SPHERE are discovering gap structures in protoplanetary disks at an ever faster pace. Some of these gaps may be opened by planets forming in the disks. In order to constrain planet formation models using disk observations, it is crucial to find a robust way to quantitatively back out the properties of the gap-opening planets, in particular their masses, from the observed gap properties, such as their depths and widths. Combining 2D and 3D hydrodynamics simulations with 3D radiative transfer simulations, we investigate the morphology of planet-opened gaps in near-infrared scattered-light images. Quantitatively, we obtain correlations that directly link intrinsic gap depths and widths in the gas surface density to observed depths and widths in images of disks at modest inclinations under finite angular resolution. Subsequently, the properties of the surface density gaps enable us to derive the disk scale height at the location of the gap h, and to constrain the quantity M
p
2/α, where M
p is the mass of the gap-opening planet and α characterizes the viscosity in the gap. As examples, we examine the gaps recently imaged by VLT/SPHERE, Gemini/GPI, and Subaru/HiCIAO in HD 97048, TW Hya, HD 169142, LkCa 15, and RX J1615.3-3255. Scale heights of the disks and possible masses of the gap-opening planets are derived assuming each gap is opened by a single planet. Assuming α = 10−3, the derived planet masses in all cases are roughly between 0.1 and 1 M
J.
Theory and Transport of Nearly Incompressible Magnetohydrodynamic Turbulence
Authors: Zank G. P. , Adhikari L. , Hunana P. , Shiota D. , Bruno R. , Telloni D.
Published: January 2017

The theory of nearly incompressible magnetohydrodynamics (NI MHD) was developed largely in the early 1990s, together with an important extension to inhomogeneous flows in 2010. Much of the focus in the earlier work was to understand the apparent incompressibility of the solar wind and other plasma environments, and the relationship of density fluctuations to apparently incompressible manifestations of turbulence in the solar wind and interstellar medium. Further important predictions about the “dimensionality” of solar wind turbulence and its relationship to the plasma beta were made and subsequently confirmed observationally. However, despite the initial success of NI MHD in describing fluctuations in the solar wind, a detailed application to solar wind turbulence has not been undertaken. Here, we use the equations of NI MHD to describe solar wind turbulence, rewriting the NI MHD system in terms of Elsässer variables. Distinct descriptions of 2D and slab turbulence emerge naturally from the Elsässer formulation, as do the nonlinear couplings between 2D and slab components. For plasma beta order 1 or less regions, predictions for 2D and slab spectra result from the NI MHD description, and predictions for the spectral characteristics of density fluctuations can be made. We conclude by presenting a NI MHD formulation describing the transport of majority 2D and minority slab turbulence throughout the solar wind. A preliminary comparison of theory and observations is presented.
Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?
Authors: Hopkins Philip F. , Conroy Charlie
Published: January 2017

Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances of these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in these species agrees with our simulations. Moreover, we confirm that Mg and Si are correlated in these stars; the abundance ratios are similar to those in local silicate grains. Meanwhile [Mg/Ca], predicted to be nearly invariant from pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.
Instabilités politiques, guerre et croissance économique : le cas du Liban et des pays du Moyen-Orient
Authors: Verne Jean-François
Published: January 2017

Cet article s’intéresse à l’influence des guerres et des instabilités politiques sur l’évolution du taux de croissance du PIB dans quinze pays du Moyen-Orient et plus particulièrement au Liban durant la période 1970-2013. Il analyse ainsi l’asymétrie dans la variation du taux de croissance du PIB de ces quinze pays et détermine de manière endogène un seuil de croissance autour duquel les guerres ou les instabilités politiques exercent deux niveaux d’impact sur le taux de croissance. Il en résulte que les économies des quinze pays passent brutalement d’un régime de récession à un régime de croissance et que le seuil de croissance est relativement élevé. Ce constat est particulièrement pertinent pour le Liban qui, de plus, affiche une certaine résilience puisque l’évolution de son PIB, très erratique notamment durant la guerre civile de 1975-1990, revient rapidement vers sa valeur de long terme suite à un choc.
Internet et la fabrique du couple binational homosexuel
Authors: Awondo Patrick
Published: January 2017

Résumé L'article analyse la formation des couples binationaux homosexuels par la médiation d'internet. En partant de l'exemple de couples franco-camerounais rencontrés entre 2008 et 2011 à Paris, il interroge les modalités des rencontres gaies internationales. Il s'attarde sur la façon dont internet change la position relative qu'occupent les sujets de cette étude dans leurs cadres sociaux respectifs. D'un côté des enquêtés français d'un certain âge tentent d'échapper à l'isolement et à leur « mise sur la touche » dans certains milieux homosexuels parisiens. De l'autre côté, des jeunes Camerounais essayent d'échapper au contexte de pénalisation de l'homosexualité et de violence homophobe devenue endémique au tournant des années 2000. Ensemble ces couples qui se retrouvent sur la Toile redessinent la géographie de l'homosexualité et permettent de rediscuter quelques enjeux de l'internationalisation de la question homosexuelle ; il en est ainsi par exemple de la nomination de soi comme homosexuel et de la fabrique offline du couple qui n'est pas sans tensions.
Conseiller à Pôle emploi
Authors: Pillon Jean-Marie
Published: January 2017

Résumé En 2009, les Assedic et l'ANPE, ont fusionné au sein de Pôle emploi pour créer un corps de 35 000 « référents uniques » capables de suivre les chômeurs tant en matière d'indemnisation que de placement. Si la pratique de l'indemnisation avait l'image d'un « sale boulot » pour les agents ANPE, quelques-uns se sont appropriés le « métier » des ex-Assedic et, ce faisant, ont acquis une position ascendante dans les collectifs de travail. À partir d'une ethnographie du travail, nous souhaitons tirer les fils de ces recompositions pour interroger les liens entre la prescription d'une politique et l'écologie des groupes mandatés pour l'appliquer.
Preparation and preservation of viable Akkermansia muciniphila cells for therapeutic interventions
Authors: Ouwerkerk J.P. , Aalvink S. , Belzer C. , De Vos W.M.
Published: January 2017

The anaerobic gut bacterium Akkermansia muciniphila is a well-characterised member of the mucosal microbiota and has shown to be a gut symbiont in human. A. muciniphila has been negatively associated with obesity and its associated metabolic disorders in various human cohorts while treatment with A. muciniphila cells reversed highfat diet-induced obesity and its associated metabolic disorders in mouse models. Therefore, administration of A. muciniphila has been suggested as a possible new therapeutic treatment for these omnipresent diseases. Here we describe a potentially scalable workflow for the preparation and preservation of high numbers of viable cells of A. muciniphila obtained from 1 l laboratory scale growth under strict anaerobic conditions for therapeutic interventions. This resulted in viable A. muciniphila cells with high yields and very high stability, with up to 97.9±4.5% survival for a time period of 1 year at -80 °C in glycerol-amended medium. Moreover, various quality assessment and control procedures were developed to ensure the use of viable cells of A. muciniphila. Several microscopic, culturing, and molecular approaches were applied to monitor the presence, abundance and recovery of A. muciniphila before, during, and after its administration to high-fat treated mice. We show that viable A. muciniphila cells can be recovered from caecal and colon content (up to 1×1010 cells/g), testifying for the efficiency of the described workflow.
Assessment of the synbiotic properites of human milk oligosaccharides and Bifidobacterium longum subsp. infantis in vitro and in humanised mice
Authors: Musilova S. , Modrackova N. , Hermanova P. , Hudcovic T. , Svejstil R. , Rada V. , Tejnecky V. , Bunesova V.
Published: January 2017

The mode of delivery plays a crucial role in infant gastrointestinal tract colonisation, which in the case of caesarean section is characterised by the presence of clostridia and low bifidobacterial counts. Gut colonisation can be modified by probiotics, prebiotics or synbiotics. Human milk oligosaccharides (HMOs) are infant prebiotics that show a bifidogenic effect. Moreover, genome sequencing of Bifidobacterium longum subsp. infantis within the infant microbiome revealed adaptations for milk utilisation. This study aimed to evaluate the synbiotic effect of B. longum subsp. infantis, HMOs and human milk (HM) both in vitro and in vivo (in a humanised mouse model) in the presence of faecal microbiota from infants born by caesarean section. The combination of B. longum and HMOs or HM reduced the clostridia and G-bacteria counts both in vitro and in vivo. The bifidobacterial population in vitro significantly increased and produce high concentrations of acetate and lactate. In vitro competition assays confirmed that the tested bifidobacterial strain is a potential probiotic for infants and, together with HMOs or HM, acts as a synbiotic. It is also able to inhibit potentially pathogenic bacteria. The synbiotic effects identified in vitro were not observed in vivo. However, there was a significant reduction in clostridia counts in both experimental animal groups (HMOs + B. longum and HM + B. longum), and a specific immune response via increased interleukin (IL)-10 and IL-6 production. Animal models do not perfectly mimic human conditions; however, they are essential for testing the safety of functional foods.
Use of technological innovations in broadening the application of equine exercise physiology
Authors: Foreman J.H.
Published: January 2017

The quadrennial International Conference on Equine Exercise Physiology (ICEEP) allows focused presentations of a variety of horse exercise- and performance-related research data in cardiorespiratory, muscle, biomechanics, nutrition, genomics, and applied physiology. The most diverse section of the ICEEP meeting has been termed variously ‘Applied Exercise Physiology’ (ICEEP 8 and 9), ‘Applied Physiology: Training Methods, Exercise Testing and Selection’ (ICEEP 7), or ‘Applied Physiology of Athletic Performance’ (ICEEP 6 and earlier). The next ICEEP meeting is scheduled to be held in Australia in 2018. In this subspeciality of equine exercise physiology, scientists attempt to apply or put into practical field use the techniques and tools developed in the more basic sciences in order to assess the performance, training, and injury of horses working and performing under true, non-laboratory conditions. The real test of the value of this subspeciality will be the increased application and sustainability of the use of laboratory techniques in the assessment of equine athletes in field settings. This review summarises exercise physiology findings prior to the widespread use of equine laboratory treadmills which have tethered investigators to the laboratory, and explains and illustrates newer, more portable, often digital technological developments which have allowed investigations to move out of the laboratory and back to the field setting where horses train and compete on a daily basis.
IL-6/STAT3 growth signalling induced by exercise conditioning promotes regeneration of injured rat sciatic nerve: return to an old cytokine
Authors: Ashour H. , Rashed L.A. , Sabry M.M.
Published: January 2017

The effects of interleukin-6 (IL-6), a growth promoting myokine through signal transduction, and activator of transcription 3 (STAT3), as a growth promoting signal, in peripheral nerve injury (PNI) are still unclear, including whether exercise pre- and/or post-conditioning are useful in nerve regeneration. Four groups were included in the study: sham for sciatic nerve injury (control), sciatic nerve injury group (SNI), exercise post-conditioning (SNI+Ex) and exercise pre- and post-conditioning (Ex+SNI+Ex). IL-6 levels were measured in serum, muscle, nerve and its surrounding fascia. Elevated levels of IL-6 in serum, nerve, muscle and fascia revealed that IL-6 induced in nerve by exercise were: (1) local nerve tissue expression; (2) serum diffused as a myokine from contracting muscle; and (3) diffused for surrounding peri-tendinous region. Evaluation of nerve functions shows that, exercise post-conditioning significantly improved (P<0.05) nerve functions in the form of nerve conduction velocity (NCV) (19.21±4.30 vs 10.96±3.08 m/s), compound muscle action potential amplitude (CMAP) (0.26±0.06 vs 0.18±0.06 mv), histologic improvement in myelination% (35.63±3.92 vs 21.13±4.26) and number of nerve fibres (181.75±9.6 vs 145.75±9.67). However, combined pre- and post-conditioning improved NCV (26.95±2.41 vs 19.21±4.30 m/s) and % myelination (43.50±3.16 vs 35.63±3.92) (P<0.05) when compared with the exercise post-conditioning group. In conclusion, IL-6 induced by exercise is valuable in nerve regeneration. The IL-6/STAT3 growth pathway could be a treatment target in clinical trials in PNI conditions.
Nursing Student Coaches for Emergency Department Super Utilizers
Authors: Anderson Della , Patch Enedina , Oxandale Brooke , Kincade Amy , Gamber Angie , Ohm Ruth
Published: January 2017

Background:

The Super Utilizer Project is a collaboration between an integrated health care organization and a baccalaureate school of nursing. The goal is to help the super utilizers access appropriate health care resources through the use of a student coach model.

Method:

The student coaches provide clients with disease prevention and health promotion education and assistance specific to the clients' unique health care needs. The tenets of the theoretical frameworks of servant leadership, caring theory, and transtheoretical model of behavior change are applied throughout this project.

Results:

First-year outcomes for the project were encouraging, with the total number of visits for 23 super utilizers to the emergency department decreasing from 710 annually to a projected 510 annually, and second-semester visits for 20 clients decreased from 634 to a projected 462.

Conclusion:

The students experience complex client care and collaboration with an interdisciplinary team reducing nonemergent emergency department super utilizer visits. [
J Nurs Educ.
2017;56(1):27–30.]
Health and Nutritional Literacy of New Zealand Nursing Students
Authors: Mearns Gael J. , Chepulis Lynne , Britnell Sally , Skinner Kelly
Published: January 2017

Background:

The published literature suggests that RNs are more overweight and obese than the general population. This research investigates associations between nutrition literacy, anthropometry measures, and nutritional biomarkers in an undergraduate nursing student population.

Method:

Year-one nursing students from two tertiary education institutions in New Zealand were invited to participate in an observational, convenience sample study. Data collection from participants (
N
= 103) included a nutrition literacy questionnaire, anthropometry measures, and blood lipid, glucose, and HbA1c concentrations.

Results:

Approximately 51% of participants were either overweight or obese, which is a similar prevalence to the New Zealand demographic-matched population. Mean body mass index was 26.7 ± 6.3 kg/m
2
and body fat was 29% ± 8.3%. The mean literacy score was 56.7% ± 13.2%. The literacy score was inversely associated with anthropometry measures and total cholesterol/high-density lipoprotein cholesterol ratio and positively associated with high-density lipoprotein cholesterol.

Conclusions:

Nutrition literacy had a statistically significant influence on anthropometry and lipid measures. [
J Nurs Educ.
2017;56(1):43–48.]
Aportaciones de la arqueología subacuática al patrimonio organológico
Authors: Alonso Yllana Jesús
Published: January 2017

El presente artículo se centra en el estudio de los restos de instrumentos musicales hallados en excavaciones arqueológicas subacuáticas en diferentes partes del mundo. Esos restos no han sido objeto de estudio hasta la fecha, exceptuando alguna investigación parcial.
En primer lugar se catalogan, posibilitando así que el musicólogo tenga acceso a estos documentos que tienen la ventaja de no haber sufrido modificaciones de épocas posteriores como sucede en muchos casos en los instrumentos conservados en tierra. Se establece así una vía de comunicación efectiva entre el trabajo de los arqueólogos subacuáticos y los musicólogos.
En segundo lugar, se expone el estudio de uno de los instrumentos catalogados que por su importancia histórica es digno de destacar entre los hallados. Dicho estudio consiste en un análisis de los restos y un estudio musicológico sobre el instrumento.
A Cinema’s Female Worker in a Musical Key: Ana Satrova
Authors: Sánchez Rodríguez Virginia
Published: January 2017

Despite the remote origin of women in music, today the presence of names of women dedicated to musical composition remains limited in historiography. Also references to fi lm music composers are even more unusual, although cinema is probably the most important art in the 20th Century. According to these circumstances, in this paper we propose an approach to Ana Satrova, a composer of original soundtracks who worked in the Spanish film area between 1969 and 1985. In this occasion, we offer a stylistic and visual studio about his first work in the Spanish cinema of Franco’s regime: Homicidios en Chicago (1969, José María Zabalza)
La profanation du montage
Authors: Hildebrandt Toni
Published: January 2017

Cet article examine les liens entre, pour l’aspect technique, le plan séquence et le montage, et, pour l’aspect philosophico-historique, la vie quotidienne et la politique mondiale, du point de vue d’une profanation capable de désamorcer la puissance et avec une attention particulière portée à l’unique film expérimental de Pasolini : La sequenza del fiore di (1968). Ce court métrage n’a pas seulement un statut spécial dans la filmographie de Pasolini, il marque aussi un tournant du tragique vers un ton comique/pessimiste de son cinéma profanateur. Cet article révèle aussi une réception inattendue de Heidegger, par l’intermédiaire du marxisme heideggerien de Karel Kosik et d’une conception benjaminienne du profane fondée sur l’idée de bonheur.
La poétique de la parabole chez Pier Paolo Pasolini : autour du film La Ricotta
Authors: Kim Simon
Published: January 2017

La Ricotta est un moyen métrage pour lequel Pasolini fut condamné pour blasphème. Il met en scène le tournage de la Passion du Christ mais en s’attardant sur un pauvre figurant, Stracci, engagé pour tenir le rôle du bon larron. Affamé, Stracci se gave de ricotta juste avant le tournage de la scène où il doit figurer "crucifié". Pris d’indigestion, il meurt devant la caméra.À côté de la critique sociale, ce film, court par sa durée, n’en est pas moins extrêmement riche. Qu’il s’agisse de la mise en abyme du film dans le film, mais aussi de la Passion (réelle de Stracci) dans la Passion (filmée du Christ), ou de l’interview très sardonique du réalisateur (interprété par Orson Welles), le film porte en lui un condensé de la pensée pasolinienne dans laquelle morale, religion et politique ne sont pas séparées, mais également où littérature, cinéma et poésie sont liés ensemble, participant de ce que nous appelons une poétique de la parabole.
Numerical Analysis of the Oscillating Water Column (OWC) Wave Energy Converter (WEC) Considering Different Incident Wave Height
Authors: Gomes Mateus das Neves , Amado Eduardo Alves , dos Santos Elizaldo Domingues , Isoldi Liércio André , Rocha Luiz Alberto Oliveira
Published: January 2017

The ocean wave energy conversion into electricity has been increasingly researched in the last years. There are several proposed converters, among them the Oscillating Water Column (OWC) device has been widely studied. The present paper presents a two-dimensional numerical investigation about the fluid dynamics behavior of an OWC Wave Energy Converter (WEC) into electrical energy. The main goal of this work was to numerically analyze the optimized geometric shape obtained in previous work under incident waves with different heights. To do so, the OWC geometric shape was kept constant while the incident wave height was varied. For the numerical solution it was used the Computational Fluid Dynamic (CFD) commercial code FLUENT®, based on the Finite Volume Method (FVM). The multiphasic Volume of Fluid (VOF) model was applied to tackle with the water-air interaction. The computational domain is represented by the OWC device coupled with the wave tank. This work allowed to check the influence of the incident wave height on the hydropneumatic power and the amplification factor of the OWC converter. It was possible to identify that the amplification factor increases as the wave period increases, thereby improving the OWC performance. It is worth to highlight that in the real phenomenon the incident waves on the OWC device have periods, lengths and height variables.
Estimate of the Wave Climate on the Most Energetic Locations of the South-Southeastern Brazilian Shelf
Authors: Oleinik Phelype Haron , Marques Wiliam Correa , Kirinus Eduardo de Paula
Published: January 2017

The wave energy availability has become a field of intensive research around the world. In this sense, this study aims to estimate the wave climate at the most energetic spots on the South-Southeastern Brazilian Shelf (SSBS). To achieve this goal, the sea state model TOMAWAC was used to simulate 18 years of wave conditions on the SSBS. The results showed that the sites at Santa Marta cape and Ilhabela are quite similar, with mean wave height of 1.4 m and period of 8.5 s along the climatological year. Farol island, on the other hand, showed higher averages, of 1.7 m and 8.9 s for wave height and period, respectively. The annual behavior of the wave parameters showed greater stability at Santa Marta cape and Ilhabela, and less at Farol island. The mean wave power yield at the Santa Marta cape and Ilhabela is nearly 10 kW/m and at Farol island, 15 kW/m. A wavelet analysis pointed that the most energetic events are those with periods of occurrence from 6 to 12 days, with the apex at 7 days. The wavelet analysis also showed that the most energetic spectrum is the one at Farol island, with 2.5 times the energy of the other locations at the period band of 7 days.
Constructal Design of Double-T Shaped Cavity with Stochastic Methods Luus-Jaakola and Simulated Annealing
Authors: Gonzales Gill Velleda , dos Santos Elizaldo Domingues , Isoldi Liércio André , Rocha Luiz Alberto Oliveira , da Silva Neto Antônio José , Telles Wagner Rambaldi
Published: January 2017

In this paper it is proposed a comparison between two stochastic methods, Simulated Annealing and Luus-Jaakola algorithms, applied in association with Constructal Design to the geometric optimization of a heat transfer problem. The problem consists in a solid body with an internal uniform heat generation, which is cooled by an intruded cavity that is maintained at a minimal temperature. The other surfaces are kept as adiabatic. The objective is to minimize the maximum excess of temperature (θmax) in the solid domain through geometric optimization of the isothermal double-T shaped cavity. The problem geometry has five degrees of freedom, but in this study four degrees of freedom are evaluated, keeping fixed the ratio H/L (ratio between the height and length of the solid domain) as well as the cavity constraints. The search for the optimal geometry is performed by Simulated Annealing and the Luus-Jaakola algorithm with different configurations or set of main parameters. Each algorithm is executed twenty times and the results for θmax, and corresponding geometry ratios, are recorded. Results of two heuristics are compared in order to select the best method for future studies about the complete optimization of the cavity, as well as, the evaluation of constraints over the thermal performance of the problem. The method employed to compare and rank the different versions of the two algorithms is a statistical tool called multi-comparison of Kruskal-Wallis. With this statistical method it is possible to classify the algorithms in three main groups. Results showed that the Simulated Annealing with hybrid parameters of Cooling Schedule (BoltzExp and ConstExp2) and traditional ones (Exponential) led to the highest probability to find the global optimal shape, while the results obtained with the Luus-Jaakola algorithm reached to several local points of minimum far from the best shape for all versions of the algorithm studied here. However, the Luus-Jaakola algorithm led to the lowest magnitude of maximum excess of temperature, showing that the implementation of hybrid methods of optimization can be an interesting strategy for evaluation of this kind of problem.
The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg
Authors: Hitzler Leonhard , Charles Amandine , Öchsner Andreas
Published: January 2017

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.
Modification of VO2 Nano-Powders by Stearic Acid and its Mechanism
Authors: Chen Yan Wu , Wang Feng , Hu Jian Qing , Tu Wei Ping
Published: January 2017

Stearic acid was applied to modify the VO2 nanopowders, and the influence of modified medium, dosage of modifier, amount of activator, time of modification on the surface modification effect were studied. The modification parameters such as modifying agent and the conditions were optimized. The changes of Surface groups, particle size and the lipophilic degree of the dispersion system of VO2 nanopowders before and after modified by the stearic acid were researched. The modification mechanism is chemical bonding, which is not physical adsorption. And then the stearic acid modified mechanism was established and applied to explain the the process of modification parameters optimization. The modification of VO2 nanopowders could be used in color nanometer energy-saving coating.
Influencing Factors of Setting Time about Magnesium Phosphate Cement
Authors: Wen Jin Bao , Tang Xiu Sheng , Huang Guo Hong , Zhu Ye Ran
Published: January 2017

Because the setting time of magnesium phosphate cement (MPC) was too quick, its further application was restricted. Influence factors about magnesium phosphate cement setting time are summarized and the influence laws are studied in the paper. The results show that with the increase of phosphorus to magnesium ratio (P/Mg) or boron to magnesium ratio (B/Mg), the setting time is both obviously prolonged. The effect of water to binder ratio (W/C) on the setting time of MPC has an optimal point. As the specific surface area increases gradually, the setting time of MPC is greatly shortened. Although fly ash has effect on setting time of MPC, the effect is very small. At the same time, the setting time is closely related with environmental temperature, the pH value of the system and mixing volume.
Experimental Study on Strain and Damage Inspection of Cementitious Composites In-Filled with Graphene Nanoplatelets
Authors: Liu Qiong , Gao Run Dong , Wang Zhuo Lin
Published: January 2017

Recent investigations show that graphene nanoplatelets (GNPs) are promising nanosized additives to enhance the smartness of cementitious composites. To investigate the strain variation of smart cementitious composites in-filled with GNPs, a cyclic compressive load within elastic regime is employed on a mortar specimen containing 6.4% GNPs (by the amount of cement) when the electrical resistance is being measured. Additionally, the damage of the smart mortar specimen is shown according to the curve of the relationship between resistance and external force. The results show that the strain is linearly proportional with the resistance variation within elastic regime. The gradient of the resistance can show the damage status during loading failure pressure.
Effects of Cement Additives on Alinite Cement-Based Materials from Municipal Solid Waste Incineration (MSWI) Fly Ash
Authors: Guo Xiao Lu , Shi Hui Sheng , Huang Jia Bao
Published: January 2017

Municipal solid waste incineration (MSWI) fly ash was successfully used as a main raw material in sintering and preparing alinite cement clinker in laboratory. Based on this, this work focused on the effects of cement admixtures on the compressive strength and durability of the alinite cement-based materials. The optimum mix mass ratio was confirmed, i.e. the mass ratio of alinite cement clinker / gypsum / cement additives (MSWI fly ash, fly ash, or slag) was 80 % / 5 % / 15 %. The experimental results showed that addition of cement additives could improve resistance to sulfate attack of the prepared alinite cement-based materials. The resistance to carbonation and water permeability could be improved by adding different cement additives. The effectiveness is specimen AD3 (with 15 wt. % slag) > AB3 (with 15 wt. % MSWI fly ash) > AC3 (with 15 wt. % fly ash). However, addition of cement additives had negative effects on the dry shrinkage. Finally, with the hydration ages increasing, the content of soluble chloride ion from alinite cement specimen AB3 was decreased. It would be stable in long term. This work improves utilization of industrial solid wastes as cement additives in the prepared alinite cement from MSWI fly ash. It is beneficial for our understanding and application of alinite composite cement as construction and building materials.
Experimental Study on the Impact of Macrosegregation Formation of the Al-Bi Hypermonotectic Alloys
Authors: Kang Zhi Qiang , Yang Xue , Feng Guo Hui , Zhang Lin
Published: January 2017

The solidification experiments about macrosegregation formation of the Al-10%Bi hyper monotectic alloys under gravity conditions have been carried out. The results showed that the average diameter of the Bi-rich droplets linearly increases and the number density of the Bi-rich droplets exponentially decreases with solidification time under the gravity condition. Because of gravity settling and collisions coagulation between the droplets, area fraction of Bi-rich increased rapidly in the bottom of samples during early solidification. It’s easy to form Bi-rich layer at the bottom of the sample. The analysis demonstrates that nucleation and diffusion growth of drops are the dominant factors influencing the solidification microstructure during the early solidification and the same distribution of Bi-rich in different locations of sample. As the solidification process, gravity migration and collision coagulation beginning to play the leading role, lead to the difference in the distribution of Bi-rich droplets in different locations of sample 90%e5%a2%9e%e5%a4%a7&tjType=sentence&style=&t=increases+gradually" increases gradually in the same time. It caused macrosegregation of the final solidification microstructure under the gravity condition.
Thermal Stability of Geopolymer - Sr Contaminated Zeolite A Blends
Authors: Jiang Zao , Xu Zhong Hui , Shuai Qin , Li Ping , Xu Ya Hong
Published: January 2017

Geopolymer have gradually become an alternative materials for hazardous and radioactive waste immobilization. However, the compatibility between radioactive waste and geopolymer in various extreme conditions are still not clear. In this study, the thermal stability of geopolymer solidified product of Sr contaminated zeolite A was investigated. For this purpose, the specimens after standard curing were subjected to temperatures of 600, 700 and 800 degrees C for 2h. Freeze-thaw cycles were also employed to test the thermal stability of geopolymer matrices. Meanwhile, changes in the leaching characteristics and physical properties were analyzed. Analysis showed that geopolymer - Sr contaminated zeolite A blends exhibited excellent thermal stability. Although elevated temperature and freeze-thaw cycles led to the deterioration of geopolymer matrices, the leaching rate and mechanical properties of solidified product were still acceptable. The resluts obtained indicated that geopolymer appeared to be very suitable for radioactive waste immobilization.
Investigation of Microstructure and Deformation Behavior of a Mg-Gd-Y Alloy Processed by ECAP and Aging Treatment
Authors: Liu Ran , Huang Ping , Wang Jing Tao , Liu Jin Qiang
Published: January 2017

The combined strengthening effect of grain refinement by equal channel angular pressing (ECAP) and aging on a wrought Mg-12Gd-3Y-0.5Zr (mass fraction, %) alloy was investigated. The resulting mechanical properties and microstructures were examined by uniaxial tensile test, optical microscope (OM) and transmission electronic microscope (TEM). It is found that ECAP for 4 passes at 673K followed by aging treatment at 523K for 16h is the optimum condition to strengthen the selected alloy Microstructure analysis reveals that precipitates appear at grain boundaries, accompanies by a few precipitates in grain interior after ECAP and aging treatment. By contrast of as-annealed sample, the strength and elongation were improved which revealed that grain boundaries and precipitation hardening were the main contributor to the high tensile strength of the experimental alloy.
Enhanced Interfacial Bonding Properties in Non-Equilibrium State between Aluminum Matrix and Ultrafined Ni-Nb Glassy Particulate Reinforcements
Authors: Wang Da Peng , Du Xing Hao , Wu Bao Lin , Liu Yan Dong
Published: January 2017

In this paper, highly scattered fine-scale Ni-Nb base glassy particles were successfully produced by wet milling method. The Al-based metal matrix composites (MMC) comprising pure Al matrix and different amounts of Ni-Nb glassy powder reinforcement were fabricated by powder metallurgy, and their mechanical properties were examined by compression tests at room temperature. It’s proved that only the 2.5 to 5 wt.% addition of the glassy reinforcements enhanced significantly the yield strength of pure Al from 120 to near 200 MPa, while keeping considerable plastic deformation before the fracture strain at about 25%. These results showed that the highly scattered fine-scale glassy particles were efficient reinforcements in fabricating high-performance Al based MMC. The high yield strength of such composites blended with the low mass fraction of glassy particulates was roughly analyzed using Orowan shear model. Finally, the ductile fracture characteristics of the composites were analyzed by evaluating the Ni-Nb glassy/Al metallic interface energy.
Microstructural Evolution of TP347H upon Long-Term Service in Power Plants
Authors: Fang Chao , He Yin Sheng , Yoo Keun Bong , Jung Jine Sung , Shin Kee Sam
Published: January 2017

Effects of welding and long-term service on the microstructural evolution of superheater tubes of TP347H stainless steel used in power plants were investigated by optical microscope (OM), scanning electron microscope (SEM), electron back-scattered diffraction (EBSD), and transmission electron microscope (TEM). Analyses after welding or long-term service, showed fine NbCs in grains, which will precipitaion strengthen the matrix. When TP347 was long-term serviced in power plants, M23C6 formed preferentially on the grain boundaries and on twin boundaries, which was attributed to the embrittlement and the intergranular corrosion and fracture. The steam side had less recrystallization rate and more oxide compared to the fire side, which is part of the reason for the cracking from steam side to the fire side. And HAZ is more brittle than the matrix, because of α-Fe phase and coarse grains, due to which, cracks tend to initiate in the steam side of HAZ and propagate to the fire side.
High Frequency Electrical Properties of Fe/SiO2 Composites by Pressureless Sinter
Authors: Xie Pei Tao , Wang Zhong Yang , Fan Run Hua , Qian Lei , Fan Guo Hua
Published: January 2017

In this paper, Fe/SiO2 composites with different Fe content were prepared through pressureless sinter in weakly reductive atmosphere after high energy ball milling. The electrical properties including ac conductivity, permittivity were investigated in detail. The results showed that the frequency dispersions of ac conductivity follow the power law, indicating the hoping conduction behavior. The real part of permittivity for composites increased with higher Fe content, which was attributed to the more interface between Fe and SiO2. Besides, Debye-like dielectric relaxations were observed, and the Debye-like loss peak appeared blue shift as increasing the Fe content.
TiO2 Nanoparticles Synthesized with Ti(SO4)2 as Precursor via the Hydrothermal Method and their Optical Absorption Properties
Authors: Fu Xiao Ming
Published: January 2017

Anatase TiO2 particles of about 20 nm in the diameter were successfully synthesized with Ti (SO4)2 as titanium source and stronger ammonia water as precipitant at 240°C for 48 h with pH=5 using the hydrothermal method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible absorption spectroscopy (UV-VIS). XRD analysis showed that the phase of the samples was anatase TiO2. TEM analysis confirmed that TiO2 particles of about 50 nm in the diameter were obtained when the pH value was 0.12. With the increasement of the pH value, the size of as-prepared TiO2 particles became remarkably fine. However, with the further increase of the pH value, the size of TiO2 particles was not obvious. TiO2 particles of about 20 nm in the diameter were obtained when the pH value was 5. And UV-VIS results showed that the size of anatase TiO2 nanoparticles, which became small, was propitious to the blue shift of their absorption peak.
Fabrication of g-C3N4 Microspheres without Template via Microwave Heating Method
Authors: Yu Yong Zhi , Wang Ji Gang
Published: January 2017

This research reported the preparation of the graphitic carbon nitride (g-C3N4) microspheres without template via microwave heating method using melamine as precursor. The as-synthesized samples were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-Vis) and photoluminescence (PL). Results showed that the g-C3N4 microspheres were successfully synthesized. The diameters of the microspheres range from 800 nm to 1.5 μm, and the shell thickness is about 50 nm. UV-Vis absorption edge and PL peak of the g-C3N4 were shown at 457 nm and 468 nm, respectively, indicating the intrinsic semiconductor-like absorption in the blue region of the visible spectrum. This was the first attempt to prepare g-C3N4 microspheres without template via microwave heating approach, which was proved to be facile and effective.
Glutathione-Directed Green Synthesis of Ag Nanoclusters with Highly Fluorescence
Authors: Yan Lei , Yu Yan Lin , Xiao Dan
Published: January 2017

A facile green method to synthesize fluorescent Ag nanoclusters (NCs) has been developed by employing glutathione (GSH) as capping agent as well as reducing agent. The fluorescent nanocomposites powder possesses strong emission and excellent stability. By changing the mole ratios of glutathione to silver precursor, nanoclusters with different emissions are obtained. The as-synthesized GSH-Ag nanocomposite is well characterized by fluorescence spectroscopy, HRTEM, XPS, and IR spectroscopy. The green synthesis procedure has also been used to synthesize fluorescent GSH-Au nanoclusters with good success.
The Addition of Zr in Nickel-Based Inconel 718 Superalloy to Prevent Hot Cracks Propagation
Authors: Zhao Heng , Liu Qing Bin , Lee Gang , Yao Da Wei
Published: January 2017

The Inconel 718 alloy owes high strength and ductility at high temperature due to precipitation strengthening. In order to upgrade productility of Inconel 718 alloy, the Inconel 718 alloy solve hot crackings through Zr additions. The result shows that, the Inconel 718 alloy with Zr addition achieves grain size refinement and homogenization effect. It is suggested that, homogenization process, such as temperature point and time control, realizes low content of Nb segregation which is the key to prevent hot crackings. At the same time, through dendrite space measurement, the grain refinement realize high productivity of forged Inconel 718 alloy, as a another method of soft effect. In conclusion, adding Zr element is one of dominant methods for producing high quality of Inconel 718 alloy.
A Review - The Properties and Applications of Nano-Structured Titanium Oxide Materials
Authors: Wu Xiao Ping
Published: January 2017

Because of the unique optical properties, titanium dioxide (TiO2) has been widely used as a white pigment over several decades. The numerous and diverse applications of TiO2 can be found in many common products such as paints, plastics, paper, sunscreens, etc. In the past decades, the emergence of nanotechnology and the discovery of some of the key application potentials of TiO2 have spurred the enormous interests to study TiO2, particularly, nano-structured TiO2, as the functional materials. Since then, substantial advances have been made in the fabrication, characterization, fundamental understanding of TiO2 nano-materials, and their promising applications in a number of areas such as energy and environment. This review will discuss the properties of nano-structured TiO2 and highlight the recent development of their applications.
Facile Fabrication of Bimetallic PtCo Nanoparticles Supported on Three-Dimensional Reduced Graphene Oxide by Ultrasonic-Assisted Method for Oxygen Reduction Reaction
Authors: Li Yi , Yang Juan , Xu Kai
Published: January 2017

High platinum requirements in electrocatalyst bring about huge expenditure, which hinders the commercialization and wide adoption of proton electrolyte membrane fuel cells (PEMFCs). Therefore, developing new fuel cell catalysts with excellent oxygen reduction reaction (ORR) performance may be a potential way to solve this drawback. In this paper, a facile ultrasonic-assisted method is introduced to synthesize bimetallic PtCo nanoparticles supported on three-dimensional reduced graphene oxide (Pt-Co/3DrGO). Results indicate that PtCo nanoparticles with alloy structure, small size (12.4 nm), and uniform distribution are well-dispersed onto rGO sheets. With 3D porous structure, the fabricated Pt-Co/3DrGO catalyst exhibits better ORR activity and long-term stability than that of commercial Pt/C (20 wt%). The increased electrocatalytic activity is attributed to the formation of 3D porous structure together with the effective surface structure and the highly uniform distribution of the PtCo alloy nanoparticles on rGO sheets.