bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of physical inactivity on arterial compliance during a glucose challenge
Authors: Credeur Daniel P. , Reynolds Leryn J. , Holwerda Seth W. , Vranish Jennifer R. , Young Benjamin E. , Wang Jing , Thyfault John P. , Fadel Paul J. 
Published: January 2018

New Findings
What is the central question of this study?
To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity.

What is the main finding and its importance?
During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day−1) and not when they were engaging in regular physical activity (>10,000 steps day−1). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia.

AbstractAcute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co‐morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High‐resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat‐to‐beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day−1). Compliance and β‐stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or β‐stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2 mmHg−1 versus 120 min OGTT, 0.06 ± 0.02 mm2 mmHg−1; P < 0.001) and femoral β‐stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.
Pharmacological modulation of mitochondrial calcium homeostasis
Authors: Arduino Daniela M. , Perocchi Fabiana 
Published: January 2018

AbstractMitochondria are pivotal organelles in calcium (Ca2+) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems‐level pharmacological targeting of mitochondrial Ca2+ homeostasis.
image
Evolving changes in fetal heart rate variability and brain injury after hypoxia‐ischaemia in preterm fetal sheep
Authors: Yamaguchi Kyohei , Lear Christopher A. , Beacom Michael J. , Ikeda Tomoaki , Gunn Alistair J. , Bennet Laura 
Published: January 2018

Key points
Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic‐ischaemic brain injury after birth.
In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia‐ischaemia. Both mild and severe hypoxia‐ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury.
Severe hypoxia‐ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable.
These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective.
AbstractHypoxia‐ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short‐term variation, long‐term variation, standard deviation of normal to normal R‐R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3–4 h in the 15 min group and 1–2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short‐term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI.
Quench Polish Quench (QPQ) Coating Behavior Under Dynamic Loads
Authors: Zhao Haifeng , Torres Abraham , Prisbell Andrew , Werner Andrew , Abdelaal Ahmed 
Published: January 2018

The selection of coating or surface treatments is a crucial step in the design of oil and gas equipment to protect against the deterioration caused by wear, corrosion, galling, fatigue, etc. Quench polish quench (QPQ) nitriding is a superior candidate to increase surface hardness for abrasion and galling resistance in carbon or stainless steels. The increased surface hardness improves the wear and corrosion resistance but reduces the surface material ductility. It is generally not recommended for application to V-shaped threads or sharp notches subjected to high stress.
During well perforation in cased-hole completion, the detonation of the gun string along with the induced pressure wave in fluids generates a large-magnitude dynamic motion in the gun string. The peak load of a perforating event, from detonation to fluid-structure interaction, happens in the range of microseconds to milliseconds. The coupled wellbore hydrodynamic and structural dynamic shock load may cause an overstress failure in the millisecond scale but is usually overlooked in engineering practice.
In this work, we investigated the behavior of QPQ coating under transient dynamic loads, employing both physical test and finite element analysis. We designed a combination of drop test fixture and specimens to simulate a notched specimen subjected to dynamic tensile loads. Two types of specimens were prepared in this study, QPQ-coated specimens and bare metal specimens without coating. The specimens without coating were tested to serve as a baseline for comparison. The methodology in this study provides a generic guideline for design of equipment potentially subjected to transient mechanical shock loads.
Stress-Induced Acceleration of the Change of Microstructure of Ni-Base Superalloy CM247LC
Authors: Suzuki Ken , Miura Hideo 
Published: January 2018

The degradation process of Ni-base superalloy CM247LC was investigated experimentally under the creep loading at 900°C. The initial excellent high-temperature strength of this alloy is attributed to its micro texture, the fine binary phase such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix). However, it was observed that γ’ precipitates started to coarse perpendicular to the applied uniaxial load direction during high temperature creep loading. The disappearance of the strengthened micro texture caused the acceleration of the crack growth along the phase boundaries of the layered texture and seriously degrades the strength of this material. Therefore, not only the outlook of micro texture but also the changes of the atomic configuration and atomic concentration which were based on the atomic diffusion behavior was investigated for the further explication of rafting mechanism more in detail.
It was found that the distribution of Image Quality (IQ) value which was obtained from EBSD analysis monotonically shifted to lower values and the full width of half maximum became wider as the creep loading time increased. This degradation of the order of atomic alignment indicated that lattice defects density increased and ordered superlattice structure (Ll2 structure) became disordered. In addition, the initial periodic distributions of component elements which corresponded to the fine periodic alignment of the γ and γ’ phases also disappeared and the concentration of each element became uniform even though both the γ and γ’ phases still remained even after rafting. The observed creep damage of CM247LC was, therefore, dominated by the degradation of the order of atomic arrangement, and this degradation was attributed to the strain-induced atomic diffusion of component elements. It is very important, therefore, to suppress this strain-induced acceleration of atomic diffusion in this alloy by modifying the microstructure of this alloy.
Post-Fatigue Creep and Stress Relaxation Response of a Hybrid Polymer Composite
Authors: Prakash Raghu V. , Maharana Monalisha 
Published: January 2018

Polymer composites have a characteristic, composition specific visco-elastic property which influences the damage progression during fatigue cycling. While some researchers have studied the time dependent constitutive response of polymer composites during the first cycle of fatigue loading, very few have experimentally investigated the dependence of visco-elastic response of built-up polymer composite materials at various stages of fatigue cycling [1]. Our earlier studies on fatigue response of polymer composites focused primarily on the stiffness degradation as a function of applied cycles of loading, which represents the gross response of the material [2]. While doing such an experiment, complimentary experimental techniques to measure the temperature evolution was attempted through the use of infrared thermal imaging technique, which gave some insight into the change in temperature response as a function of fatigue cycling. However, there was no systematic measurement of creep and stress relaxation response of the composite material as a function of induced fatigue damage.
The present paper describes the results of creep and stress-relaxation obtained during uni-axial fatigue loading of a hybrid polymer composite material. For this purpose, a woven carbon fiber mat was chosen as the synthetic fiber and Flax fiber in the unidirectional form was chosen as the natural fiber that is laid between the two layers of woven carbon fiber mat. Epoxy LY 556 and hardener Araldite® was used for building up of composite laminate by hand-lay-up technique. Dog-bone shaped tensile specimens with a gage width of 13 mm and gage length of 57 mm were extracted from the 250 × 250 mm sq. plate laminate of 2.1 mm thickness using a numerical controlled milling machine. The specimens were tested at 35% of their median tensile strengths under fatigue at a positive stress ratio (Pmin/Pmax) of 0.1 in tension-tension loading. Prior to start of fatigue loading, the specimens were held in load control and the strain in the gage length was measured for understanding the creep response over 2500 seconds. For stress-relaxation characterization, the specimens were held in extensometer control over a period of 2500 sec. The creep and stress relaxation tests were carried out after periodic intervals of fatigue cycling.
It was observed that in the case of un-impacted specimens, the creep rate is consistent with the stiffness variation, which in turn, is dependent on the number of fatigue cycles - till it showed signs of de-lamination. Thereafter it was governed by the woven synthetic fiber response. Similarly, the stress relaxation response was found to decrease with increasing fatigue cycles. In case of impacted specimens, the local deformation had a prominent role in terms of creep and stress relaxation response.
RPM-Synchronous Grinding: Control Concepts to Improve Surface Qualities for a Highly Efficient Non-Circular Grinding Approach
Authors: Steffan Matthias , Haas Franz , Spenger Thomas 
Published: January 2018

The RPM-Synchronous Grinding process offers new possibilities to generate defined macro- and micro-geometries on workpieces. With present technology, various macroscopic non-circular geometries must be grinded subsequently in an oscillating process where the X-axis is coupled with the rotary workpiece-spindle axis. Such workpieces can be machined in an ordinary plunge grinding process by implementing the approach of RPM-Synchronous Non-Circular Grinding. Therefore, the workpiece and the grinding wheel rotational rates are in a fixed ratio. A non-circular grinding wheel is used to transfer its geometry onto the workpiece. The authors use a unique machine tool for basic research and control concept development for RPM-Synchronous Grinding (RSG). The machine was especially designed for this RSG technology. Highest revolution rates on the workpiece spindle are mandatory for its success. The grinding approach is performed in a two-step process. For roughing, a highly porous vitrified bonded grinding wheel with medium grain size is used. It ensures high specific material removal rates for producing the non-circular geometry on the workpiece efficiently. A control algorithm adapts this process step, which uses acquired data from a piezoelectric three-component force sensor fixed at the tailstock-side of the grinding machine. For finishing, a grinding wheel with fine grain size is suited. This process step is tuned by a digital process adaption strategy. Roughing and finishing are performed consecutively among the same clamping of the workpiece with two locally separated grinding spindles.
With the presented control and adaption concepts for RPM-Synchronous Grinding, a significant increase in surface quality on the workpiece is attained. The minimization of grinding wheel wear results concurrently. Especially the automotive industry shows big interest in RPM-Synchronous Non-Circular Grinding. This emerging trend in finishing machining opens up various fields of application.
Axiomatic Design of an Adjustable Lifting System for the Assembly of Booms of Telehandlers
Authors: Landi Luca , Sorgenti Agnese , Clerini Denny 
Published: January 2018

This work describes the Axiomatic Design of a lifting system to be used during the assembly of various telescopic lift booms. The main function of the lifting system is to assist the workers during both the pre-assembly of the individual parts of a boom and also during the final assembly of a wide ranges of telescopic booms of telehandlers. Prior to the design of the lifting system the fundamental phase of data collection work is described in the paper. The company production process is analysed to detect the needs and design constraints impacting directly on the design stage. The preliminary design stage included: functional, ergonomic study of the lifting system and also considerations on the safety of operators during assembly.
The Axiomatic Design allows the designer to implement the Customer Needs into Functional Requirements and Design Parameters through a matrix description. So the product designer can recognize and properly transform Functional Requirements into Design Parameters during early stages of the design.
In the paper the development of this new lifting system is shown through Axiomatic Design method. The resulting modular lifting system and the principal results obtained will be described in terms of:
- reduction of assembly space on the “moving assembly chain” of the company,
- reduction of cycle time of the assembly of the boom using the new lifting system,
- improvement of ergonomic conditions of workers.
During the so called decoupling phase of Axiomatic Design, the Design Parameters of the lifting system are first determined and then hierarchically ordered. So the wasted time for typical trial and error process of advanced design stage is reduced because of this clear ordering.
The physical prototype of the new lifting system was already built and successfully used for the assembly on the industrial field.
Adapting Vertically Integrated Projects to University Team Competitions
Authors: Chipman Gregory D. , Fuller Thomas F. 
Published: January 2018

Beginning in 2009 Vertically Integrated Projects (VIP) courses have been implemented at Georgia Tech. These VIP classes allow undergraduate students to receive academic credit for participating on teams that further faculty research efforts. The teams are: multidisciplinary, vertically-integrated, and long-term. Participation on these teams has been shown to help students gain understanding of project timelines, effective project communication, and other applicable real-world experience.
EcoCAR 3 is the latest in a series of Advanced Vehicle Technology Competitions (AVTCs) sponsored by the Department of Energy since 1988. At Georgia Tech, the EcoCAR 3 team has been structured using the VIP program to improve the all-around experience of faculty members and the graduate and undergraduate students. Based on Georgia Tech’s experience in the first three years in EcoCAR 3, we have learned lessons that we are implementing on our team to improve the educational experience of the students working on the project. One of these lessons is the value of strong undergraduate leadership on competition teams and in project based learning. The benefits have included a more evenly distributed workload, increased mentorship of new undergraduate students, and improved team capability to successfully meet deadlines while still educating undergraduate team members.
Evaluating Material Property Variations in Components With Difficult Geometries
Authors: Amine Tarak , Newkirk Joseph W. , O’Malley Ronald J. 
Published: January 2018

All manufacturing methods produce components which have some degree of inhomogeneous properties. Part properties may vary with location in most fabrication methods including additive manufacturing, casting, forging, welding, and surface modifications. Standard tensile test specimens cannot provide a good map of the properties of the material, except for only the largest of components or simplest of geometries. For example, simple curved shapes, such as pipes cannot be reliably evaluated by straight tensile specimens unless the pipe diameter is large enough to have a sufficiently low curvature from which flat specimens can be machined.
This paper will look at part property variations in various components made by different fabrication methods, which include selective laser melting, press and sinter powder metallurgy, rolling and casting. Subsize tensile specimens developed at the Missouri University of Science and Technology have been used to map out material properties with location. This method of mapping out properties provides new information which could be valuable to quality control, process control, and design of components.
Development and Validation of a Finite Element Lower Limb Model for Elderly Females
Authors: Khandelwal Prashant , Kalra Anil , Jiang Binhui , Hammad Anand , Jin Xin , Yang King H. 
Published: January 2018

Physical surrogates and numerical models have been used to investigate the lower limb injury responses in blunt trauma related to occupant and pedestrian impacts during crash events. To date, automotive crash dummies used for studying the lower limb kinematics and injury responses in car crashes are designed to represent mid-age adults. But due to increase in fragility and frailty with age, the injury risk of the lower limb of elderly females is greater compared to younger adults. Thus, safety designs should expand for protecting elderly females in lower limb impacts.
The current study focuses on developing a lower limb finite element model for elderly females with accurate anthropometry and anatomical details. The model was further validated against segmental and whole-body level experimental data of lower limb impact during pedestrian, frontal, and side impact loading. The validated model will be further integrated into the whole-body model to study injury mechanisms and safety designs for this vulnerable population of elderly females.