bluuebunny/crossref_metadata_2025 huggingface dataset:
An approach to comprehensive genome and proteome expression analyses in Schwann cells and neurons during peripheral nerve myelin formation
Authors: Kangas Salla M. , Ohlmeier Steffen , Sormunen Raija , Jouhilahti Eeva‐Mari , Peltonen Sirkku , Peltonen Juha , Heape Anthony M.
Published: July 2016

Peripheral nerve myelination is a complex event resulting from spatially and temporally regulated reciprocal interactions between the neuron and myelin‐forming Schwann cells. The dynamic process and the protein functional modules and networks that operate throughout the myelination process are poorly understood because of a lack of methodologies suitable for observing specific changes in the Schwann cell/neuron‐unit. The identification of the precise roles for the proteins participating in the functional modules and networks that participate in the myelination process is hindered by the cellular and molecular complexity of the nervous tissue itself. We have developed an approach based on a myelinating dorsal root ganglion explant model that allows distinguishing clear, reproducible and predictable differences between the biochemical properties and the genomic and proteomic expression profiles of both cellular components of the Schwann cell/neuron unit at different stages of the myelination process. This model, derived from E13.5 C57BL/6J mouse embryos, is sufficiently robust for use in identifying the protein functional networks and modules related to peripheral nerve myelin formation. The genomic expression profiles of the selected neuronal, Schwann cell and myelin‐specific proteins in the cultures reflect in vivo profiles reported in the literature, and the structural and ultrastructural properties of the myelin, as well as the myelination schedule of the cultures, closely resemble those observed in peripheral nerves in situ. The RNA expression data set is available through NCBI gene expression omnibus accession GSE60345.

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We have developed a reproducible and robust cell culture‐based approach, accompanied by a genome‐wide expression data set, which allows studying myelination in the peripheral nervous system at the proteomic and transcriptomic levels in Schwann cells and neurons. Myelinating dorsal root explant cultures, prepared from C57BL/6J mouse embryos, present distinct developmental stages comparable to those observed in a peripheral nerve in situ. This model can be used for identifying the protein functional networks and modules related to peripheral nerve myelin formation.
Photodynamic therapy versus surgical excision to basal cell carcinoma: meta‐analysis
Authors: Zou Yurui , Zhao Yunxiang , Yu Jia , Luo Xue , Han Jiangbo , Ye Zhijia , Li Jintao , Lin Hui
Published: July 2016

Background

Surgical excision (SE) is a first‐line treatment for basal cell carcinoma (BCC). Topical photodynamic therapy (PDT) has also been used and has cosmetic advantages over surgery. The latest European guidelines for topical PDT recommended that it be used to treat nodular basal cell carcinoma (nBCC) but a consensus has not been reached. Our study was to evaluate the efficacy of PDT versus SE for the treatment for nBCC by a meta‐analysis.

Materials and methods

We searched PubMed, EMBASE, the Cochrane Library, CKNI, VIP, and relevant references up to October 2014 including randomized controlled trials (RCTs) that compared PDT with SE for treatment of nBCC patients. A meta‐analysis was conducted by using the Cochrane Collaboration's revman 5.0 software.

Results

We selected five studies that covered 596 of pathologically confirmed nBCC. We compared complete response rate (RR) of PDT and SE at 3 months and 1, 2, 3, 4, and 5 years. We found that the RR was 0.95 (0.90, 1.00), 0.89 (0.80, 0.99), 0.83 (0.69, 1.00), 0.73 (0.63, 0.85), 0.84 (0.65, 1.08), and 0.79 (0.61, 1.03), respectively, for those time points, the cumulative probability of recurrence for the time points post‐treatment, with an estimate at RR 5.28 (1.85, 15.12), 6.48 (2.46, 17.09), 9.67 (3.02, 30.99), 7.73 (2.81, 21.28), and 8.25 (3.01–22.62), respectively.

Conclusion

We observed no significant differences between PDT and SE for the complete RR, but there was an increased cumulative probability of recurrence. More large‐scale RCTs are required to verify our findings.
The Influence of Agreeableness and Ego Depletion on Emotional Responding
Authors: Finley Anna J. , Crowell Adrienne L. , Harmon‐Jones Eddie , Schmeichel Brandon J.
Published: July 2016

Objective

Agreeable individuals report more intense withdrawal‐oriented negative emotions across aversive situations. Two studies tested the hypothesis that self‐regulatory depletion (i.e., ego depletion) moderates the relationship between trait Agreeableness and negative emotional responding.

Method

Ego depletion was manipulated using a writing task. Emotional responding was measured with startle eye‐blink responses (Study 1, N = 71) and self‐reported valence, arousal, and empathic concern (Study 2, N = 256) during emotional picture viewing. Trait Agreeableness was measured using a questionnaire.

Results

In Study 1, Agreeableness predicted especially large startle responses during aversive images and especially small startles during appetitive images. After exercising self‐control, the relationship between startle magnitudes and Agreeableness decreased. In Study 2, Agreeableness predicted more empathic concern for aversive images, which in turn predicted heightened self‐reported negative emotions. After exercising self‐control, the relationship between Agreeableness and empathic concern decreased.

Conclusions

Agreeable individuals exhibit heightened negative emotional responding. Ego depletion reduced the link between Agreeableness and negative emotional responding in Study 1 and moderated the indirect effect of Agreeableness on negative emotional responding via empathic concern in Study 2. Empathic concern appears to be a resource‐intensive process underlying heightened responding to aversive stimuli among agreeable persons.
Influence of particle shedding from silicone tubing on antibody stability
Authors: Saller Verena , Hediger Constanze , Matilainen Julia , Grauschopf Ulla , Bechtold-Peters Karoline , Mahler Hanns-Christian , Friess Wolfgang
Published: July 2016

Objectives

Peristaltic pumps are increasingly employed during fill & finish operations of a biopharmaceutical drug, due to sensitivity of many biological products to rotary piston pump-related stresses. Yet, possibly also unit operations using peristaltic pumps may shed particulates into the final product due to abrasion from the employed tubing. It was the aim of this study to elucidate the potential influence of particles shed from peristaltic pump tubing on the stability of a drug product.

Methods

Spiking solutions containing shed silicone particles were prepared via peristaltic pumping of placebo under recirculating conditions and subsequently characterized. Two formulated antibodies were spiked with two realistic, but worst-case levels of particles and a 6-month accelerated stability study with storage at 2–8, 25 and 40°C were conducted.

Key findings

Regarding the formation of aggregates and fragments, both mAbs degraded at their typically expected rates and no additional impact of spiked particles was observed. No changes were discerned however in turbidity, subvisible and visible particle assessments. Flow imaging data for one of the mAb formulations with spiked particles suggested limited colloidal stability of shed particles as indicated by a similar increase in spiked placebo.

Conclusions

Shed silicone particles from peristaltic pump tubing are assumed to not impair drug product stability.
Genomic variation at the tips of the adaptive radiation of Darwin's finches
Authors: Chaves Jaime A. , Cooper Elizabeth A. , Hendry Andrew P. , Podos Jeffrey , De León Luis F. , Raeymaekers Joost A. M. , MacMillan W.Owen , Uy J. Albert C.
Published: July 2016

Adaptive radiation unfolds as selection acts on the genetic variation underlying functional traits. The nature of this variation can be revealed by studying the tips of an ongoing adaptive radiation. We studied genomic variation at the tips of the Darwin's finch radiation; specifically focusing on polymorphism within, and variation among, three sympatric species of the genus Geospiza. Using restriction site‐associated DNA (RAD‐seq), we characterized 32 569 single‐nucleotide polymorphisms (SNPs), from which 11 outlier SNPs for beak and body size were uncovered by a genomewide association study (GWAS). Principal component analysis revealed that these 11 SNPs formed four statistically linked groups. Stepwise regression then revealed that the first PC score, which included 6 of the 11 top SNPs, explained over 80% of the variation in beak size, suggesting that selection on these traits influences multiple correlated loci. The two SNPs most strongly associated with beak size were near genes associated with beak morphology across deeper branches of the radiation: delta‐like 1 homologue (DLK1) and high‐mobility group AT‐hook 2 (HMGA2). Our results suggest that (i) key adaptive traits are associated with a small fraction of the genome (11 of 32 569 SNPs), (ii) SNPs linked to the candidate genes are dispersed throughout the genome (on several chromosomes), and (iii) micro‐ and macro‐evolutionary variation (roots and tips of the radiation) involve some shared and some unique genomic regions.
McCabe and Aquinas on Love and Natural Law
Authors: Heron Jason A.
Published: July 2016

This article investigates the relationship between love, law, and human nature in the thought of McCabe and Aquinas. The article puts McCabe and Aquinas into conversation in order to illuminate McCabe's estimation of the natural law as an “insufficient ethic” and a feature of ethics that sheds a “great deal of light” on the matter of human morality. The article seeks to articulate the integrity of natural morality as a feature of the Divine Wisdom that ultimately perfects natural morality via the incarnation of the Son.
Managing in the Regulatory Thicket: Regulation Legitimacy and Expertise
Authors: Amirkhanyan Anna A. , Meier Kenneth J. , O'Toole Laurence J.
Published: July 2016

Although the influence of government regulation on organizations is undeniable, empirical research in this field is scarce. This article investigates how the understanding of and attitudes toward government regulation among public, nonprofit, and for‐profit managers affect organizational performance, using U.S. nursing homes as the empirical setting. Findings suggest that managers’ perceptions of regulation legitimacy—views of regulation fairness, inspectors’ effectiveness, and internal utility of the mandates—positively affect service quality. Subgroup analysis suggests that managers’ views of regulation matter in nonprofit and for‐profit organizations but not in public organizations. In nonprofit homes, performance declines when managers report higher regulatory expertise—better knowledge of the regulatory standards. In for‐profit facilities, frequent communication with regulators lowers quality. These findings suggest that the regulated entities’ views of government regulation are central to their success, which necessitates improvements in the regulatory process.
Does a Regional Trade Agreement Lessen or Worsen Growth Volatility? An Empirical Investigation
Authors: Kpodar Kangni , Imam Patrick
Published: July 2016

This paper assesses how regional trade agreements (RTAs) impact on growth volatility for a sample of 170 countries over the period 1978–2012. Notwithstanding concerns that trade openness through RTAs might heighten exposure to shocks, RTAs through enhanced policy credibility, improved policy coordination and reduced risk of conflicts can also ease growth volatility. Empirical estimations suggest the benefits outweigh the costs as RTAs are consistently associated with lower growth volatility. In addition, smaller economies benefit more from the reduced growth volatility associated with RTAs than larger ones. The nature of the RTA also matters as shallow agreements such as partial‐scope preferential trade agreements do not appear to have a significant effect on growth volatility, whereas free trade areas and customs unions do. Finally, in investigating the drivers of RTAs, the regression results confirm that countries that are more prone to shocks are more likely to join an RTA, in particular with countries with relatively less volatile growth.
Optimizing sleep to maximize performance: implications and recommendations for elite athletes
Authors: Simpson N. S. , Gibbs E. L. , Matheson G. O.
Published: July 2016

Despite a growing body of literature demonstrating a positive relationship between sleep and optimal performance, athletes often have low sleep quality and quantity. Insufficient sleep among athletes may be due to scheduling constraints and the low priority of sleep relative to other training demands, as well as a lack of awareness of the role of sleep in optimizing athletic performance. Domains of athletic performance (e.g., speed and endurance), neurocognitive function (e.g., attention and memory), and physical health (e.g., illness and injury risk, and weight maintenance) have all been shown to be negatively affected by insufficient sleep or experimentally modeled sleep restriction. However, healthy adults are notoriously poor at self‐assessing the magnitude of the impact of sleep loss, underscoring the need for increased awareness of the importance of sleep among both elite athletes and practitioners managing their care. Strategies to optimize sleep quality and quantity in athletes include approaches for expanding total sleep duration, improving sleep environment, and identifying potential sleep disorders.
What does normal tendon structure look like? New insights into tissue characterization in the Achilles tendon
Authors: Wezenbeek E. , Mahieu N. , Willems T. M. , Van Tiggelen D. , De Muynck M. , De Clercq D. , Witvrouw E.
Published: July 2016

Recently, ultrasound tissue characterization (UTC) was introduced as a reliable method for quantification of tendon structure. Despite increasing publications on the use of UTC, it is striking that there is a lack of normative data in active adolescents. Therefore, the aim of this study was to provide normative values of the Achilles tendon as quantified by UTC. Seventy physiotherapy students (26 male and 44 female students) with no history of Achilles tendon injuries were recruited. The Achilles tendons were scanned with UTC to characterize tendon structure. This study demonstrated that Achilles tendons of active, healthy adolescents contained 54.6% echo type I, 42.8% echo type II, 2.2% echo type III, and 0.3% echo type IV at midportion. The comparison between insertion and midportion of the tendon showed more echo type II at insertion (P < 0.001). Furthermore, female tendons contained significantly more echo type II, in both insertion and midportion compared with male tendons (P = 0.004 and P = 0.003, respectively). The results of this study, with respect to the MDC (minimum detectable change), highlight differences in the UTC echopattern in the normal population (sex and regional location), which are important considerations for future studies.
Probabilistic Finite-Element Analysis of S2-Glass Epoxy Composite Beams for Damage Initiation Due to High-Velocity Impact
Authors: Patel Shivdayal , Ahmad Suhail , Mahajan Puneet
Published: July 2016

The safety predictions of composite armors require a probabilistic analysis to take into consideration scatters in the material properties and initial velocity. Damage initiation laws are used to account for matrix and fiber failure during high-velocity impact. A three-dimensional (3D) stochastic finite-element analysis of laminated composite plates under impact is performed to determine the probability of failure (Pf). The objective is to achieve the safest design of lightweight composite through the most efficient ply arrangement of S2 glass epoxy. Realistic damage initiation models are implemented. The Pf is obtained through the Gaussian process response surface method (GPRSM). The antisymmetric cross-ply arrangement is found to be the safest based on maximum stress and Yen and Hashin criteria simultaneously. Sensitivity analysis is performed to achieve the target reliability.
Transport Phenomena and Properties in Treelike Networks
Authors: Xu Peng , Sasmito Agus Pulung , Yu Boming , Mujumdar Arun Sadashiv
Published: July 2016

Treelike structures abound in natural as well as man-made transport systems, which have fascinated multidisciplinary researchers to study the transport phenomena and properties and understand the transport mechanisms of treelike structures for decades. The fluid flow and heat transfer in treelike networks have received an increasing attention over the past decade as the highly efficient transport processes observed in natural treelike structures can provide useful hints for optimal solutions to many engineering and industrial problems. This review paper attempts to present the background and research progress made in recent years on the transport phenomenon in treelike networks as well as technological applications of treelike structures. The subtopics included are optimization of branching structures, scaling laws of treelike networks, and transport properties for laminar flow, turbulent flow, heat conduction, and heat convection in treelike networks. Analytical expressions for the effective transport properties have been derived based on deterministic treelike networks, and the effect of branching parameters on the transport properties of treelike networks has also been discussed. Furthermore, numerical simulation results for treelike microchannel networks are presented as well. The proposed transport properties may be beneficial to understand the transport mechanisms of branching structures and promote the applications of treelike networks in engineering and industry.
Comparison Between Casson Fluid Flow in the Presence of Heat and Mass Transfer From a Vertical Cone and Flat Plate
Authors: Jasmine Benazir A. , Sivaraj R. , Rashidi M. M.
Published: July 2016

The present study explores the influence of viscous dissipation, Joule heating, and double dispersion on unsteady, free convective magnetohydrodynamics (MHD) flow of an incompressible Casson fluid over a vertical cone and flat plate saturated with porous medium subject to variable viscosity and variable electrical conductivity. The governing coupled, nonlinear partial differential equations are solved by Crank–Nicolson method. The effects of various significant parameters on flow, heat, and mass transfer characteristics are displayed in the form of figures and tables. The results indicate that the presence of variable viscosity parameter meagerly accelerates the fluid flow. It is observed that heat transfer is enhanced for increasing the thermal dispersion parameter and Eckert number.
Determination of Cooling Parameters for a High-Speed, True-Scale, Metallic Turbine Vane
Authors: Polanka Marc D. , Rutledge James L. , Bogard David G. , Anthony Richard J.
Published: July 2016

Facilities such as the Turbine Research Facility (TRF) at the Air Force Research Laboratory have been acquiring uncooled heat transfer measurements on full-scale metallic airfoils for several years. The addition of cooling flow to this type of facility has provided new capabilities and new challenges. Two primary challenges for cooled rotating hardware are that the true local film temperature is unknown, and cooled thin-walled metallic airfoils prohibit semi-infinite heat conduction calculation. Extracting true local adiabatic effectiveness and the heat transfer coefficient from measurements of surface temperature and surface heat transfer is therefore difficult. In contrast, another cooling parameter, the overall effectiveness (ϕ), is readily obtained from the measurements of surface temperature, internal coolant temperature, and mainstream temperature. The overall effectiveness is a normalized measure of surface temperatures expected for actual operating conditions and is thus an important parameter that drives the life expectancy of a turbine component. Another issue is that scaling ϕ from experimental conditions to engine conditions is dependent on the heat transfer through the part. It has been well-established that the Biot number must be matched for the experimentally measured ϕ to match ϕ at engine conditions. However, the thermal conductivity of both the metal blade and the thermal barrier coating changes substantially from low-temperature to high-temperature engine conditions and usually not in the same proportion. This paper describes a novel method of replicating the correct thermal behavior of the thermal barrier coating (TBC) relative to the metal turbine while obtaining surface temperature measurements and heat fluxes. Furthermore, this paper describes how the ϕ value obtained at the low-temperature conditions can be adjusted to predict ϕ at high-temperature engine conditions when it is impossible to match the Biot number perfectly.
History of the Fluids Engineering Division
Authors: Cooper Paul , Samuel Martin C. , O'Hern Timothy J.
Published: July 2016

The 90th Anniversary of the Fluids Engineering Division (FED) of ASME will be celebrated on July 10–14, 2016 in Washington, DC. The venue is ASME's Summer Heat Transfer Conference (SHTC), Fluids Engineering Division Summer Meeting (FEDSM), and International Conference on Nanochannels and Microchannels (ICNMM). The occasion is an opportune time to celebrate and reflect on the origin of FED and its predecessor—the Hydraulic Division (HYD), which existed from 1926–1963. Therefore, the FED Executive Committee decided that it would be appropriate to publish concurrently a history of the HYD/FED. Accordingly, they commissioned Paul Cooper, C. Samuel Martin, and Timothy O'Hern to prepare this paper, which would document the division's past. A brief work in this direction had appeared in the 2010 FED Newsletter (Morgan, W. B., 2010, Brief History of ASME's Hydraulic/Fluids Engineering Division, Fluids Engineering Division Newsletter, New York, pp. 6–7), and the research by Martin for the present paper had been under way for several years prior to that (Cooper, P., 2010, “History of the FED,” FED Executive Committee at the ASME-CSME Fluids Engineering Summer Conference (FEDSM-2010), Montréal, QC, Canada, Aug., p. 14).
Experimental and Theoretical Determination of Diffusion Coefficients of CO2-Heavy Oil Systems by Coupling Heat and Mass Transfer
Authors: Zheng Sixu , Yang Daoyong
Published: July 2016

By treating heavy oil as multiple pseudocomponents, techniques have been developed to experimentally and theoretically determine diffusion coefficients of CO2-heavy oil systems by coupling heat and mass transfer together with consideration of swelling effect. Experimentally, diffusion tests have been conducted for hot CO2-heavy oil systems with three different temperatures under a constant pressure by using a visualized pressure-volume-temperature (PVT) setup. The swelling of liquid phase in the PVT cell is continuously monitored and recorded during the measurements. Theoretically, a two-dimensional (2D) mathematical model incorporating the volume-translated Peng–Robinson equation of state (PR EOS) with a modified alpha function has been developed to describe heat and mass transfer for hot CO2-heavy oil systems. Heavy oil sample has been characterized as three pseudocomponents for accurately quantifying phase behavior of the CO2-heavy oil systems, while the binary interaction parameters (BIPs) are tuned with the experimentally measured saturation pressures. The diffusion coefficient of hot CO2 in heavy oil is then determined once the discrepancy between the experimentally measured dynamic swelling factors and theoretically calculated ones has been minimized. During the diffusion experiments, heat transfer is found to be dominant over mass transfer at the beginning and reach its equilibrium in a shorter time; subsequently, mass transfer shows its dominant effect. The enhanced oil swelling mainly occurs during the coupled heat and mass transfer stage. CO2 diffusion coefficient in heavy oil is found to increase with temperature at a given pressure, while it can be explicitly correlated as a function of temperature.
Auto-Ignition Characteristics Study of Gas-to-Liquid Fuel at High Pressures and Low Temperatures
Authors: Askari Omid , Elia Mimmo , Ferrari Matthew , Metghalchi Hameed
Published: July 2016

Onset of auto-ignition of premixed gas-to-liquid (GTL)/air mixture has been determined at high pressures and low temperatures over a wide range of equivalence ratios. The GTL fuel used in this study was provided by Air Force Research Laboratory (AFRL), designated by Syntroleum S-8, which is derived from natural gas via the Fischer–Tropsch (F–T) process. A blend of 32% iso-octane, 25% n-decane, and 43% n-dodecane is employed as the surrogates of GTL fuel for chemical kinetics study. A spherical chamber, which can withstand high pressures up to 400 atm and can be heated up to 500 K, was used to collect pressure rise data, due to combustion, to determine the onset of auto-ignition. A gas chromatograph (GC) system working in conjunction with specialized heated lines was used to verify the filling process. A liquid supply manifold was used to allow the fuel to enter and evaporate in a temperature-controlled portion of the manifold using two cartridge heaters. An accurate high-temperature pressure transducer was used to measure the partial pressure of the vaporized fuel. Pressure rise due to combustion process was collected using a high-speed pressure sensor and was stored in a local desktop via a data acquisition system. Measurements for the onset of auto-ignition were done in the spherical chamber for different equivalence ratios of 0.8–1.2 and different initial pressures of 8.6, 10, and 12 atm at initial temperature of 450 K. Critical pressures and temperatures of GTL/air mixture at which auto-ignition takes place have been identified by detecting aggressive oscillation of pressure data during the spontaneous combustion process throughout the unburned gas mixture. To interpret the auto-ignition conditions effectively, several available chemical kinetics mechanisms were used in modeling auto-ignition of GTL/air mixtures. For low-temperature mixtures, it was shown that auto-ignition of GTL fuel is a strong function of unburned gas temperature, and propensity of auto-ignition was increased as initial temperature and pressure increased.
Elastic Field and Frequency Variation in Extendable Wind Turbine Blades
Authors: John Jeswin , Radford Donald W. , Venayagamoorthy Subhas Karan , Heyliger Paul R.
Published: July 2016

The behaviors of tip displacement, maximum stress, and natural frequency of vibration as a function of blade length are investigated for extendable wind turbine blades. A three-dimensional linear elasticity finite-element model of the blade is used along with a typical profile and representative material properties. The quasi-linear response and free vibration behavior are investigated for a sequence of blade geometries. These estimates are intended to give approximate measures of expected changes in the elastic and dynamic field as the operating length changes and provide preliminary guidelines for this novel class of structure.
Evaluation of System Evolvability Based on Usable Excess
Authors: Allen Jeffrey D. , Mattson Christopher A. , Ferguson Scott M.
Published: July 2016

Complex, large-scale engineered systems are an integral part of modern society. The cost of these systems is often high, while their ability to react to emergent requirements can be low. This paper proposes evolvability, based on usable excess, as a possible metric to promote system longevity. An equation for the usability of excess, previously defined only in terms of quantity, is improved to include the attributes of type, location, and form as well as quantity. A methodology for evaluating a system's evolvability is also presented. Using an automated assembly line as an example, we show that system evolvability can be modeled as a function of usable excess.
A Projection-Based Approach for Constructing Piecewise Linear Pareto Front Approximations
Authors: Kumar Singh Hemant , Shankar Bhattacharjee Kalyan , Ray Tapabrata
Published: July 2016

Real-life design problems often require simultaneous optimization of multiple conflicting criteria resulting in a set of best trade-off solutions. This best trade-off set of solutions is referred to as Pareto optimal front (POF) in the outcome space. Obtaining the complete POF becomes impractical for problems where evaluation of each solution is computationally expensive. Such problems are commonly encountered in several fields, such as engineering, management, and scheduling. A practical approach in such cases is to construct suitable POF approximations, which can aid visualization, decision-making, and interactive optimization. In this paper, we propose a method to generate piecewise linear Pareto front approximation from a given set of N Pareto optimal outcomes. The approximations are represented using geometrical linear objects known as polytopes, which are formed by triangulating the given M-objective outcomes in a reduced (M−1)-objective space. The proposed approach is hence referred to as projection-based Pareto interpolation (PROP). The performance of PROP is demonstrated on a number of benchmark problems and practical applications with linear and nonlinear fronts to illustrate its strengths and limitations. While being novel and theoretically interesting, PROP also improves on the computational complexity required in generating such approximations when compared with existing Pareto interpolation (PAINT) algorithm.
Temperature Increase in Forming of Advanced High-Strength Steels Effect of Ram Speed Using a Servodrive Press
Authors: Fallahiarezoodar Ali , Peker Ruzgar , Altan Taylan
Published: July 2016

In forming of advanced high-strength steel (AHSS), the temperature increase at die/sheet interface affects the performance of lubricants and die wear. This study demonstrates that finite-element (FE) analysis, using commercially available software, can be used to estimate temperature increase in single as well as in multiple stroke operations. To obtain a reliable numerical process design, the knowledge of the thermal and mechanical properties of the sheet as well as the tools is essential. Using U-channel drawing the thermomechanical FE model has been validated by comparing predictions with experimental results. The effect of ram speed and stroking rate (stroke per minute (SPM)) upon temperature increase in real productionlike operation have been investigated. Deep drawing of CP800 and DP590 sheets in a servodrive press, using an industrial scale die, has been studied. Thinning distribution and temperatures in the drawn part have been investigated in single and multiple forming operations. It is found that temperatures may reach several 100 deg and affect the coefficient of friction (COF). The values of COF under productionlike conditions were compared to that obtained from laboratory experiments. This study illustrates that in forming AHSS, (a) the temperature increase at the die/sheet interface is relatively high and should be considered in process design stage, and (b) the lubricant performance is significantly affected by the ram speed and sheet/die interface temperature during deformation.
Adaptive Detached-Eddy Simulation of Three-Dimensional Diffusers
Authors: Durbin Paul , Yin Zifei , Jeyapaul Elbert
Published: July 2016

An adaptive method for detached-eddy simulation (DES) is tested by simulations of flow in a family of three-dimensional (3D) diffusers. The adaptive method either adjusts the model constant or defaults to a bound if the grid is too coarse. On the present grids, the adaptive method adjusts the model constant over most of the flow, without resorting to the default. Data for the diffuser family were created by wall-resolved, large-eddy simulation (LES), using the dynamic Smagorinsky model, for the purpose of testing turbulence models. The family is a parameterized set of geometries that allows one to test whether the pattern of separation is moving correctly from the top to the side wall as the parameter increases. The adaptive DES model is quite accurate in this regard. It is found to predict the mean velocity accurately, but the pressure coefficient is underpredicted. The latter is due to the onset of separation being slightly earlier in the DES than in the LES.
Seam Welding of Aluminum Sheet Using Ultrasonic Additive Manufacturing System
Authors: Wolcott Paul J. , Pawlowski Christopher , Headings Leon M. , Dapino Marcelo J.
Published: July 2016

Ultrasonic welding was investigated as a method of joining 0.076 in. (1.93 mm) thick aluminum 6061 flat sheet material. Joints were produced with ultrasonic additive manufacturing (UAM) equipment in a modified application of the ultrasonic welding process. Through joint design development, successful welds were achieved with a scarf joint configuration. Using a design of experiments (DOE) approach, weld parameters including weld amplitude, scarf angle, and weld speed were optimized for mechanical strength. Lower angles and higher amplitudes were found to provide the highest strengths within the levels tested. Finite-element studies indicate that 5 deg and 10 deg angles produce an increased relative motion of the workpieces as compared to 15 deg, 20 deg, and 25 deg angles, likely leading to increased strength. Successful joints showed no indication of voids under optical microscopy. As-welded joints produce tensile strengths of 221 MPa, while heat treated joints produce tensile strengths of 310 MPa, comparable to heat treated bulk material. High-temperature tensile testing was conducted at 210 °C, with samples exhibiting strengths of 184.1 MPa, similar to bulk material. Room temperature fatigue testing resulted in cyclic failures at approximately 190,000 cycles on average, approaching that of bulk material.
Weldability and Distortion of Mg AZ31-to-Galvanized Steel SPOT Plug Welding Joint by Cold Metal Transfer Method
Authors: Cao R. , Xu Q. W. , Zhu H. X. , Mao G. J. , Lin Q. , Chen J. H. , Wang Pei-Chung
Published: July 2016

In this study, cold metal transfer (CMT) plug welding of 1 mm thick Mg AZ31 to 1 mm thick hot-dipped galvanized mild steel (i.e., Q235) was studied. Welding tests were performed and the process variables optimized with Mg AZ61 wire and 100% argon shielding gas for a plug weld located in the center of the 25 mm overlap region. It was found that it is feasible to join 1 mm thick Mg AZ31 workpiece to 1 mm thick galvanized mild steel using CMT plug welding. The optimized process variables for CMT plug welding Mg AZ31-to-galvanized mild steel were a wire feed speed of 10.5 m/min, a predrilled hole with a diameter of 8 mm in Mg AZ31 workpiece and a welding time of 0.8 s. CMT plug welded Mg AZ31-to-galvanized mild steel joints were composed of the fusion zone between Mg AZ31 base metal and Mg weld metal, Mg weld metal (i.e., combined base metal, filler wire and Zn coating), and the brazing interface between magnesium weld metal and galvanized mild steel. The brazing interface mainly consisted of Al, Zn, Mg, Si intermetallic compounds and oxides (i.e., Fe3Al, Mg2Si, MgZn, and MgZn2), and magnesium solid solution. The static strength of CMT welded-brazed Mg AZ31-galvanized steel was determined primarily by the strength and area of the brazed interface and thickness of the intermetallic reaction layer.
A New Spatial and Temporal Harmonic Balance Method for Obtaining Periodic Steady-State Responses of a One-Dimensional Second-Order Continuous System
Authors: Wang X. F. , Zhu W. D.
Published: July 2016

A new spatial and temporal harmonic balance (STHB) method is developed for obtaining periodic steady-state responses of a one-dimensional second-order continuous system. The spatial harmonic balance procedure with a series of sine and cosine basis functions can be efficiently conducted by the fast discrete sine and cosine transforms, respectively. The temporal harmonic balance procedure with basis functions of Fourier series can be efficiently conducted by the fast Fourier transform (FFT). In the STHB method, an associated set of ordinary differential equations (ODEs) of a governing partial differential equation (PDE), which is obtained by Galerkin method, does not need to be explicitly derived, and complicated calculation of a nonlinear term in the PDE can be avoided. The residual and the exact Jacobian matrix of an associated set of algebraic equations that are temporal harmonic balanced equations of the ODEs, which are used in Newton–Raphson method to iteratively search a final solution of the PDE, can be directly obtained by STHB procedures for the PDE even if the nonlinear term is included. The relationship of Jacobian matrix and Toeplitz form of the system matrix of the ODEs provides an efficient and convenient way to stability analysis for the STHB method; bifurcations can also be indicated. A complex boundary condition of a string with a spring at the boundary can be handled by the STHB method in combination with the spectral Tau method.
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Genderless Coupling Mechanism With Six-Degrees-of-Freedom Misalignment Capability for Modular
Self-Reconfigurable Robots
Authors: Saab Wael , Ben-Tzvi Pinhas
Published: July 2016

This paper presents the design and integration of a genderless coupling mechanism for modular self-reconfigurable mobile robots. Modular self-reconfigurable mobile robotic systems consist of a number of self-sufficient modules that interconnect via coupling mechanisms and adopt different configurations to modify locomotion and/or manipulation capabilities. Coupling mechanisms are a critical element of these robotic systems. This paper focuses on a docking mechanism called GHEFT: a Genderless, High-strength, Efficient, Fail-safe, and high misalignment Tolerant coupling mechanism that aids self-reconfiguration. GHEFT provides a high strength and energy efficient connection using nonback drivable actuation with optimized clamping profiles that tolerate translational and angular misalignments. It also enables engagement/disengagement without gender restrictions in the presence of one-sided malfunction. The detailed design of the proposed mechanism is presented, including optimization of the clamping profile geometries. Experimental validation of misalignment tolerances and achievable clamping forces and torques is performed to demonstrate the strength, efficiency, and fail-safe capabilities of the proposed mechanism, and these results are compared to reported results of some of the existing coupling mechanisms.
XPS analysis of Fe2O3-TiO2-Au nanocomposites prepared by a plasma-assisted route
Authors: Warwick Michael E. A. , Carraro Giorgio , Toniato Elisa , Gasparotto Alberto , Maccato Chiara , Barreca Davide
Published: July 2016

Fe2O3 nanodeposits have been grown on fluorine-doped tin oxide (FTO) substrates by plasma enhanced-chemical vapor deposition (PE-CVD). Subsequently, the obtained systems have been functionalized through the sequential introduction of TiO2 and Au nanoparticles (NPs) by means of radio frequency (RF)-sputtering. The target nanocomposites have been specifically optimized in view of their ultimate functional application in solar-driven H2 generation. In the present study, our attention is focused on a detailed X-ray photoelectron spectroscopy (XPS) characterization of the surface composition for a representative Fe2O3-TiO2-Au specimen. In particular, this report provides a detailed discussion of the analyzed C 1s, O 1s, Fe 2p, Ti 2p, and Au 4f regions. The obtained results point to the formation of pure Fe2O3-TiO2-Au composites, with gold present only in its metallic state and each of the constituents maintaining its chemical identity.
Adsorption of n-butane on graphene/Ru(0001)—A molecular beam scattering study
Authors: Sivapragasam Nilushni , Nayakasinghe Mindika T. , Burghaus Uwe
Published: July 2016

Adsorption kinetics/dynamics of n-butane on graphene, physical vapor deposited on Ru(0001) (hereafter G/Ru), and bare Ru(0001) (hereafter Ru) are discussed. The chemical activity of the supported-graphene as well as the support was probed by thermal desorption spectroscopy (adsorption kinetics). In addition and to the best of our knowledge, for the first time, molecular beam scattering data of larger molecules were collected for graphene (probing the adsorption dynamics). Furthermore, samples were inspected by x-ray photoelectron spectroscopy and Auger electron spectroscopy. At the measuring conditions used here, n-butane adsorption kinetics/dynamics are molecular and nonactivated. Binding energies of butane on Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is “kinetically transparent.” Initial adsorption probabilities, S0, of n-butane decrease with increasing impact energy (0.76–1.72 eV) and are adsorption temperature independent for both Ru and G/Ru, again consistent with molecular adsorption. Also, S0 of Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is “dynamically transparent.” Coverage dependent adsorption probabilities indicate precursor effects for graphene/Ru.
Atomic bonding effects in annular dark field scanning transmission electron microscopy. II. Experiments
Authors: Odlyzko Michael L. , Held Jacob T. , Mkhoyan K. Andre
Published: July 2016

Quantitatively calibrated annular dark field scanning transmission electron microscopy (ADF-STEM) imaging experiments were compared to frozen phonon multislice simulations adapted to include chemical bonding effects. Having carefully matched simulation parameters to experimental conditions, a depth-dependent bonding effect was observed for high-angle ADF-STEM imaging of aluminum nitride. This result is explained by computational predictions, systematically examined in the preceding portion of this study, showing the propagation of the converged STEM beam to be highly sensitive to net interatomic charge transfer. Thus, although uncertainties in experimental conditions and simulation accuracy remain, the computationally predicted experimental bonding effect withstands the experimental testing reported here.
Gas cluster ion beam for the characterization of organic materials in submarine basalts as Mars analogs
Authors: Sano Naoko , Purvis Graham W. H. , Barlow Anders J. , Abbott Geoffrey D. , Gray Neil N. D. , Cumpson Peter J.
Published: July 2016

The solar system contains large quantities of organic compounds that can form complex molecular structures. The processing of organic compounds by biological systems leads to molecules with distinctive structural characteristics; thus, the detection and characterization of organic materials could lead to a high degree of confidence in the existence of extra-terrestrial life. Given the nature of the surface of most planetary bodies in the solar system, evidence of life is more likely to be found in the subsurface where conditions are more hospitable. Basalt is a common rock throughout the solar system and the primary rock type on Mars and Earth. Basalt is therefore a rock type that subsurface life might exploit and as such a suitable material for the study of methods required to detect and analyze organic material in rock. Telluric basalts from Earth represent an analog for extra-terrestrial rocks where the indigenous organic matter could be analyzed for molecular biosignatures. This study focuses on organic matter in the basalt with the use of surface analysis techniques utilizing Ar gas cluster ion beams (GCIB); time of flight secondary ion mass spectrometry (ToF-SIMS), and x-ray photoelectron spectroscopy (XPS), to characterize organic molecules. Tetramethylammonium hydroxide (TMAH) thermochemolysis was also used to support the data obtained using the surface analysis techniques. The authors demonstrate that organic molecules were found to be heterogeneously distributed within rock textures. A positive correlation was observed to exist between the presence of microtubule textures in the basalt and the organic compounds detected. From the results herein, the authors propose that ToF-SIMS with an Ar GCIB is effective at detecting organic materials in such geological samples, and ToF-SIMS combined with XPS and TMAH thermochemolysis may be a useful approach in the study of extra-terrestrial organic material and life.
Numerical investigation of amplitude-dependent dynamic response in acoustic metamaterials with nonlinear oscillators
Authors: Manimala James M. , Sun C. T.
Published: July 2016

The amplitude-dependent dynamic response in acoustic metamaterials having nonlinear local oscillator microstructures is studied using numerical simulations on representative discrete mass-spring models. Both cubically nonlinear hardening and softening local oscillator cases are considered. Single frequency, bi-frequency, and wave packet excitations at low and high amplitude levels were used to interrogate the models. The propagation and attenuation characteristics of harmonic waves in a tunable frequency range is found to correspond to the amplitude and nonlinearity-dependent shifts in the local resonance bandgap for such nonlinear acoustic metamaterials. A predominant shift in the propagated wave spectrum towards lower frequencies is observed. Moreover, the feasibility of amplitude and frequency-dependent selective filtering of composite signals consisting of individual frequency components which fall within propagating or attenuating regimes is demonstrated. Further enrichment of these wave manipulation mechanisms in acoustic metamaterials using different combinations of nonlinear microstructures presents device implications for acoustic filters and waveguides.
Membrane- and plate-type acoustic metamaterials
Authors: Huang Tai-Yun , Shen Chen , Jing Yun
Published: July 2016

Over the past decade there has been a great amount of research effort devoted to the topic of acoustic metamaterials (AMMs). The recent development of AMMs has enlightened the way of manipulating sound waves. Several potential applications such as low-frequency noise reduction, cloaking, angular filtering, subwavelength imaging, and energy tunneling have been proposed and implemented by the so-called membrane- or plate-type AMMs. This paper aims to offer a thorough overview on the recent development of membrane- or plate-type AMMs. The underlying mechanism of these types of AMMs for tuning the effective density will be examined first. Four different groups of membrane- or plate-type AMMs (membranes with masses attached, plates with masses attached, membranes or plates without masses attached, and active AMMs) will be reviewed. The opportunities, limitations, and challenges of membrane- or plate-type AMMs will be also discussed.
Large wind ripples on Mars: A record of atmospheric evolution
Authors: Lapotre M. G. A. , Ewing R. C. , Lamb M. P. , Fischer W. W. , Grotzinger J. P. , Rubin D. M. , Lewis K. W. , Ballard M. J. , Day M. , Gupta S. , Banham S. G. , Bridges N. T. , Des Marais D. J. , Fraeman A. A. , Grant J. A. , Herkenhoff K. E. , Ming D. W. , Mischna M. A. , Rice M. S. , Sumner D. Y. , Vasavada A. R. , Yingst R. A.
Published: July 2016

Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter– to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.