bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Stall Flow Structure and Forces on Symmetrical Airfoils at High Angles of Attack and Rotation Rates
Authors: Leknys R. R. , Arjomandi M. , Kelso R. M. , Birzer C. H.
Published: November 2018

This article describes a direct comparison between two symmetrical airfoils undergoing dynamic stall at high, unsteady reduced frequencies under otherwise identical conditions. Particle image velocimetry (PIV) was performed to distinguish the differences in flow structure between a NACA 0021 and a NACA 0012 airfoil undergoing dynamic stall. In addition, surface pressure measurements were performed to evaluate aerodynamic load and investigate the effect of laminar separation bubbles and vortex structures on the pressure fields surrounding the airfoils. Airfoil geometry is shown to have a significant effect on flow structure development and boundary layer separation, with separation occurring earlier for thinner airfoil sections undergoing constant pitch-rate motion. Inertial forces were identified to have a considerable impact on the overall force generation with increasing rotation rate. Force oscillation was observed to correlate with multiple vortex structures shedding at the trailing-edge during high rotation rates. The presence of laminar separation bubbles on the upper and lower surfaces was shown to dramatically influence the steady-state lift of both airfoils. Poststall characteristics are shown to be independent of airfoil geometry such that periodic vortex shedding was observed for all cases. However, the onset of deep stall is delayed with increased nondimensional pitch rate due to the delay in initial dynamic-stall vortex.
Analytical Evaluation of Head and Flow Rate Off-Design Characteristics for Pump as Turbine Application
Authors: Mdee Ombeni John , Kimambo Cuthbert Z. , Nielsen Torbjorn K. , Kihedu Joseph
Published: November 2018

Head and flow rate are the important parameters for proper selection of centrifugal pump. However, the reversed operation of centrifugal pump leads to the off-design characteristic of head and flow rate. This paper presents an analytical model developed by using the system curves and velocity relations derived from pump application. Also, the differential technique is applied to the analytical model to develop the off-design characteristics of head ratio and flow rate ratio relations. The off-design characteristic relations were compared with literature and available conversion methods. Then, the analytical model coefficient (AMC) with the range between −4 and +4 was developed from the off-design characteristics of head ratio and flow rate ratio relations. The AMC value was equal to 1 when the pump operates in turbine mode and pump mode at the pump best efficiency point (BEP) and extended to either side up to ±4 when tested with literature data. Therefore, the analytical model consists of the off-design head and flow rate characteristics, when simplified leading to the AMC that could be applied to select the possible boundary limits of head and flow rate for different pumps.
Study on Prelithiation Technology of Hard Carbon Electrode Using Stable Metal Lithium Powder
Authors: Sun Yan-Xian , Guan Hong-Min , Jiang Zhao-Hua , Wang Zhen-Bo
Published: November 2018

The prelithiation of hard carbon electrode using stable metal lithium powder to compensate the lithium loss during the first lithium insertion is studied in this work. The results show that when the pressure on lithium powder surface is 6 MPa, the Li2CO3 protective layer on the surface of stable metal lithium powder is completely squeezed, which is conducive due to the full contact between the metal lithium and the hard carbon. The prelithiation of hard carbon has little effect on the initial charge capacity and cycle life. Both the pre-lithium capacity and the utilization efficiency of lithium powder increase with the increasing of the lithium powder content, and when the amount of lithium powder is 3 g m−2, the utilization efficiency of lithium powder is 56%.
Film Size During Bubble Collision With a Solid Surface
Authors: Emery Travis S. , Kandlikar Satish G.
Published: November 2018

The impact and bounce of a bubble with a solid surface is of significant interest to many industrial processes such as froth flotation and biomedical engineering. During the impact, a liquid film becomes trapped between the bubble and the solid surface. The pressure buildup in this film leads to the generation of a film force. The drainage rate of this film plays a crucial role in dictating the bouncing process and is known to be a function of the radial film size. However, radial film size is not an easily attained experimental measurement and requires advanced instrumentation to capture. The bouncing process has been characterized using nondimensional numbers that are representative of the bubble collision and film drainage phenomena. These are: Bond number (Bo), Archimedes number (Ar), Froude number (Fr), and the ratio of film force to buoyancy force (FF/FB). These numbers are used to define a predictive function for film radius. Experimentally validated numerical modeling has been implemented to determine the relationship between the four nondimensional numbers, and a quasi-static model is employed to relate the film force to the radial film size. Comparison of our experimental results is in agreement with the predicted film size within ±20%. From these results, the radial film size during bubble impact with a solid surface may be predicted using the easily measurable experimental parameters of bubble size, bubble impact velocity, and the liquid properties.
Spatial Corrosion Wastage Modeling of Steel Plates Exposed to Marine Environments
Authors: Garbatov Yordan , Guedes Soares C.
Published: November 2018

The objective of the present study is to identify the most suitable corrosion degradation model, fitted with real corrosion depth measurement data sets and to reproduce the corroded steel plate surface as a function of time and spatial distribution using advanced statistical methods. An approach for adequately identifying the best-fitted model to real corrosion depth measurement data sets is employed. Two distinct statistical methods for generating a statistical representation of a corroded plate surface in the case of significant and insignificant correlation of the corrosion degradation are provided. A sequence-dependent data analysis is performed based on the fast Fourier transform, which is used as an input for a random field modeling of corroded steel plate surfaces. The output of this study represents very important information about the corroded plate surface topology that can be used in any advanced finite element analyses of structural integrity assessment. The formulations can be adapted to any structural components and corrosion environments.
Power Optimization of Model-Scale Floating Wind Turbines Using Real-Time Hybrid Testing With Autonomous Actuation and Control1
Authors: Kanner Samuel , Koukina Elena , Yeung Ronald W.
Published: November 2018

Real-time hybrid testing of floating wind turbines is conducted at model scale. The semisubmersible, triangular platform, similar to the WindFloat platform, is built instead to support two, counter-rotating vertical-axis wind turbines (VAWTs). On account of incongruous scaling issues between the aerodynamic and the hydrodynamic loading, the wind turbines are not constructed at the same scale as the floater support. Instead, remote-controlled plane motors and propellers are used as actuators to mimic only the tangential forces on the wind-turbine blades, which are attached to the physical (floater-support) model. The application of tangential forces on the VAWTs is used to mimic the power production stage of the turbine. A control algorithm is implemented using the wind-turbine generators to optimize the platform heading and hence, the theoretical power absorbed by the wind turbines. This experimental approach only seeks to recreate the aerodynamic force, which contributes to the power production. In doing so, the generator control algorithm can thus be validated. The advantages and drawbacks of this hybrid simulation technique are discussed, including the need for low inertia actuators, which can quickly respond to control signals.
Effect of Axial Acceleration on Drivetrain Responses in a Spar-Type Floating Wind Turbine
Authors: Nejad Amir R. , Bachynski Erin E. , Moan Torgeir
Published: November 2018

Common industrial practice for designing floating wind turbines is to set an operational limit for the tower-top axial acceleration, normally in the range of 0.2–0.3 g, which is typically understood to be related to the safety of turbine components. This paper investigates the rationality of the tower-top acceleration limit by evaluating the correlation between acceleration and drivetrain responses. A 5-MW reference drivetrain is selected and modeled on a spar-type floating wind turbine in 320 m water depth. A range of environmental conditions are selected based on the long-term distribution of wind speed, significant wave height, and peak period from hindcast data for the Northern North Sea. For each condition, global analysis using an aero-hydro-servo-elastic tool is carried out for six one-hour realizations. The global analysis results provide useful information on their own—regarding the correlation between environmental condition and tower top acceleration, and the correlation between tower top acceleration and other responses of interest—which are used as input in a decoupled analysis approach. The load effects and motions from the global analysis are applied on a detailed drivetrain model in a multibody system (MBS) analysis tool. The local responses on bearings are then obtained from MBS analysis and postprocessed for the correlation study. Although the maximum acceleration provides a good indication of the wave-induced loads, it is not seen to be a good predictor for significant fatigue damage on the main bearings in this case.
Low Temperature Fabrication of Three-Dimensional Ceramic Substrate by Using Inorganic Alkali Activated Aluminosilicate Cement Paste for UV-LED Packaging
Authors: Cheng Hao , Yang Zi Zhou , Peng Yang , Mou Yun , Chen Ming Xiang
Published: November 2018

In this work, a low temperature method is proposed for the economical fabrication of three-dimensional (3D) ceramic substrate for Ultraviolet Light-Emitting Diodes (UV-LED) packaging. The 3D ceramic substrate using the inorganic alkali activated aluminosilicate cement paste (IAAACP) is molded by sacrificing the patterned wax mold. By controlling the viscosity, milling time, and curing temperature the of the IAAACP, the high strength 3D ceramic substrate is achieved, the corresponding shear strength reaches to 12.5MPa. After thermal shock and heat resistant test, the shear strength changed slightly, indicating the 3D ceramic substrate has excellent thermal reliability. These experimental results indicate that the prepared 3D ceramic substrate has a potential application for UV-LED packaging.
Experimental Study of Flexible Electrohydrodynamic Conduction Pumping for Electronics Cooling
Authors: Tobar Nicolas Vayas , Christidis Pavolas N. , O'Connor Nathaniel J. , Talmor Michal , Seyed-Yagoobi Jamal
Published: November 2018

As modern day electronics develop, electronic devices become smaller, more powerful, and are expected to operate in more diverse configurations. However, the thermal control systems that help these devices maintain stable operation must advance as well to meet the demands. One such demand is the advent of flexible electronics for wearable technology, medical applications, and biology-inspired mechanisms. This paper presents the design and performance characteristics of a proof of concept for a flexible Electrohydrodynamic (EHD) pump, based on EHD conduction pumping technology in macro- and meso-scales. Unlike mechanical pumps, EHD conduction pumps have no moving parts, can be easily adjusted to the micro-scale, and have been shown to generate and control the flow of refrigerants for electronics cooling applications. However, these pumping devices have only been previously tested in rigid configurations unsuitable for use with flexible electronics. In this work, for the first time, the net flow generated by flexible EHD conduction pumps is measured on a flat-plane and in various bending configurations. In this behavioral characteristics study, the results show that the flexible EHD conduction pumps are capable of generating significant flow velocities in all size scales considered in this study, with and without bending. This study also proves the viability of screen printing as a manufacturing method for these pumps.

EHD conduction pumping technology shows potential for use in a wide range of terrestrial and space applications, including thermal control of rigid as well as flexible electronics, flow generation and control in micro-scale heat exchangers and other thermal devices, as well as cooling of high power electrical systems, soft robotic actuators, and medical devices.
Experimental and Numerical Investigation of Underfill Materials on Thermal Cycle Fatigue of Second Level Solder Interconnects Under Mean Temperature Conditions
Authors: Serebreni Maxim , McCluskey Patrick , Hillman David , Blattau Nathan , Hillman Craig
Published: November 2018

With the larger size of Ball Grid Array (BGA) solder joints, the available volume for underfilling is significantly increased. Although the size of the solder joints and package dimension governs the volume of underfill material, the larger 2nd level solder interconnects are more susceptible to thermal fatigue with certain underfills and thermal profiles.

In this study, BGA packages were underfilled with two dedicated underfill materials and two soft materials used as conformal coatings and encapsulants in electronic products. Each of the selected materials was subjected to two thermal profiles, one with low mean temperature and a second with a high mean temperature. The variation in mean cyclic temperature demonstrates the influence of temperature dependent behavior of each underfill material on the loads solder joints experience in a BGA package. Material characterization was performed on the package and underfill materials and incorporated into finite element models. The influence of underfill material glass transition temperature (Tg) was found to be a critical factor on fatigue endurance of solder interconnects. Fatigue crack orientation within solder joints were found to be aligned with axial (normal) direction for BGAs with high CTE underfill materials. Simulations determined the magnitude of axial loading associated with each underfill material properties responsible for reducing fatigue life. The results developed in this paper reveal the factors associated with reduced fatigue endurance of certain underfill materials under temperature profiles with mean temperature conditions and contribute to the development of new criteria of underfill material selection for 2nd level interconnects.
Copper, Silver, and PCC Wirebonds Reliability in Automotive Underhood Environments
Authors: Lall Pradeep , Deshpande Shantanu , Nguyen Luu
Published: November 2018

Wire bonding is popular first-level interconnect method used in the semiconductor device packaging. Gold (Ag) wire is often used in high-reliability applications. Typical wire diameters vary between 0.8mil to 2mil. Recent increases in the gold-price have motivated the industry to search for alternate materials candidates for use in wirebonding. Three of the leading candidates are Silver (Ag), Copper (Cu), and Palladium Coated Copper (PCC). The new material candidates are inexpensive in comparison with gold and may have better electrical, and thermal properties, which is advantageous for fine pitch-high density electronics. The transition, however, comes along with few trade-offs such as narrow process window, higher wire-hardness, increased propensity for chip-cratering, lack of reliability knowledge base of when deployed in harsh environment applications. Relationship between mechanical degradation of the wirebond and the change in electric response needs to be established for better understanding of the failure modes and their respective mechanisms. Understanding the physics of damage progression may provide insights into the process parameters for manufacture of more robust interconnects. In this paper, a detailed study of the electrical and mechanical degradation of wirebonds under high temperature exposure is presented. Four wirebond candidates (Au, Ag, Cu and PCC) bonded onto Aluminum (Al) pad were subjected to high temperature storage life until failure to study the degradation of the bond-wire interface. Same package architecture and electronic molding compound (EMC) were used for all four candidates. Detailed analysis of intermetallic (IMC) phase evolution is presented along with quantification of the phases and their evolution over time. Ball shear strength was measured after decapsulation. Measurements of shear strength, shear failure modes, and IMC composition have been correlated with the change in the electrical response. Change in shear strength and different shear failure modes for different wirebond systems are discussed in the paper.
Comparison of Thermal and Stress Analysis Results for a High Voltage Module Using FEA and a Quick Parametric Analysis Tool
Authors: Boteler L. M. , Miner S. M.
Published: November 2018

A low order fast running parametric analysis tool, ParaPower, was used to arrive at the design for a novel high voltage module. The low order model used a 3D nodal network to calculate device temperatures and thermal stresses. The model assumed heat flux generated near the top surface of each device which is then conducted through the packaging structure and removed by convection. The temperature distribution is used to calculate thermal stresses throughout the package. This co-design modeling tool, developed for rectilinear geometries, allowed a rapid evaluation of the package temperatures and CTE induced stresses throughout the design space. However, once the final design configuration was determined a detailed finite element analysis was performed to validate the design. This paper compares the results obtained using ParaPower to the FEA, demonstrating the usefulness of the parametric analysis tool. Results for both temperature and CTE induced stress are compared. Two different stress models are evaluated. One based on the more traditional planar module design, which assumes a substantial substrate or heat spreader on which the module is assembled. The other model is less restrictive, eliminating the requirement for a substrate. The FEA modeling was performed using SolidWorks beginning with a thermal analysis followed by a stress analysis based on the temperature solution. Both the values and the trends of the temperatures and stresses were evaluated. The temperature results agreed to within 3.2°C. The trends and sign of the stresses were correctly predicted, but the magnitudes were not. One of the significant advantages of ParaPower is the speed of the computation. The run time for the parametric analysis was roughly two orders of magnitude faster than the FEA. This made it possible to build the model and complete the parametric analysis of roughly 500 runs in less than a day.
Low temperature (Ts/Tm < 0.1) epitaxial growth of HfN/MgO(001) via reactive HiPIMS with metal-ion synchronized substrate bias
Authors: Villamayor Michelle Marie S. , Keraudy Julien , Shimizu Tetsuhide , Viloan Rommel Paulo B. , Boyd Robert , Lundin Daniel , Greene Joseph E. , Petrov Ivan , Helmersson Ulf
Published: November 2018

Low-temperature epitaxial growth of refractory transition-metal nitride thin films by means of physical vapor deposition has been a recurring theme in advanced thin-film technology for several years. In the present study, 150-nm-thick epitaxial HfN layers are grown on MgO(001) by reactive high-power impulse magnetron sputtering (HiPIMS) with no external substrate heating. Maximum film-growth temperatures Ts due to plasma heating range from 70 to 150 °C, corresponding to Ts/Tm = 0.10–0.12 (in which Tm is the HfN melting point in K). During HiPIMS, gas and sputtered metal-ion fluxes incident at the growing film surface are separated in time due to strong gas rarefaction and the transition to a metal-ion-dominated plasma. In the present experiments, a negative bias of 100 V is applied to the substrate, either continuously during the entire deposition or synchronized with the metal-rich portion of the ion flux. Two different sputtering-gas mixtures, Ar/N2 and Kr/N2, are employed in order to probe effects associated with the noble-gas mass and ionization potential. The combination of x-ray diffraction, high-resolution reciprocal-lattice maps, and high-resolution cross-sectional transmission electron microscopy analyses establishes that all HfN films have a cube-on-cube orientational relationship with the substrate, i.e., [001]HfN||[001]MgO and (100)HfN||(100)MgO. Layers grown with a continuous substrate bias, in either Ar/N2 or Kr/N2, exhibit a relatively high mosaicity and a high concentration of trapped inert gas. In distinct contrast, layers grown in Kr/N2 with the substrate bias synchronized to the metal-ion-rich portion of HiPIMS pulses have much lower mosaicity, no measurable inert-gas incorporation, and a hardness of 25.7 GPa, in good agreement with the results for epitaxial HfN(001) layers grown at Ts = 650 °C (Ts/Tm = 0.26). The room-temperature film resistivity is 70 μΩ cm, which is 3.2–10 times lower than reported values for polycrystalline-HfN layers grown at Ts = 400 °C.
Relationship Between 2-Dimensional Frontal Plane Measures and the Knee Abduction Angle During the Drop Vertical Jump
Authors: Willis Brad W. , Hocker Katie , Razu Swithin , Gray Aaron D. , Skubic Marjorie , Sherman Seth L. , Kurkowski Samantha , Guess Trent M.
Published: November 2018

Context: Knee abduction angle (KAA), as measured by 3-dimensional marker-based motion capture systems during jump-landing tasks, has been correlated with an elevated risk of anterior cruciate ligament injury in females. Due to the high cost and inefficiency of KAA measurement with marker-based motion capture, surrogate 2-dimensional frontal plane measures have gained attention for injury risk screening. The knee-to-ankle separation ratio (KASR) and medial knee position (MKP) have been suggested as potential frontal plane surrogate measures to the KAA, but investigations into their relationship to the KAA during a bilateral drop vertical jump task are limited. Objective: To investigate the relationship between KASR and MKP to the KAA during initial contact of the bilateral drop vertical jump. Design: Descriptive. Setting: Biomechanics laboratory. Participants: A total of 18 healthy female participants (mean age: 24.1 [3.88] y, mass: 65.18 [10.34] kg, and height: 1.63 [0.06] m). Intervention: Participants completed 5 successful drop vertical jump trials measured by a Vicon marker-based motion capture system and 2 AMTI force plates. Main Outcome Measure: For each jump, KAA of the tibia relative to the femur was measured at initial contact along with the KASR and MKP calculated from planar joint center data. The coefficient of determination (r2) was used to examine the relationship between the KASR and MKP to KAA. Results: A strong linear relationship was observed between MKP and KAA (r2 = .71), as well as between KASR and KAA (r2 = .72). Conclusions: Two-dimensional frontal plane measures show strong relationships to the KAA during the bilateral drop vertical jump.
Distinct control of PERIOD2 degradation and circadian rhythms by the oncoprotein and ubiquitin ligase MDM2
Authors: Liu JingJing , Zou Xianlin , Gotoh Tetsuya , Brown Anne M. , Jiang Liang , Wisdom Esther L. , Kim Jae Kyoung , Finkielstein Carla V.
Published: November 2018

The oncoprotein and E3 ubiquitin ligase MDM2 ubiquitylates and promotes the degradation of the circadian clock component PER2.
MRI bone marrow oedema precedes lumbar bone stress injury diagnosis in junior elite cricket fast bowlers
Authors: Kountouris Alex , Sims Kevin , Beakley David , Saw Anna E , Orchard John , Rotstein Andrew , Cook Jill L
Published: November 2018

Objectives

Lumbar bone stress injury (‘bone stress injury’) is common in junior fast bowlers. The repetitive loading of cricket fast bowling may cause bone marrow oedema (BMO), detectable on MRI, before the bowler suffers from symptomatic bone stress injury. We investigated the temporal relationship between BMO, bone stress injury, along with bowling workload correlates, in elite junior fast bowlers throughout a cricket season.

Methods

65 junior fast bowlers were prospectively monitored for one 8-month cricket season. For research purposes, participants had up to six MRI scans at set times in the season; findings were withheld from them and their clinicians. Standard practices for bowling workload monitoring and injury diagnosis were followed.

Results

15 (23%) participants developed bone stress injury during the study. All 15 of these participants had BMO detected on at least one of the preceding MRI scans, including the scan immediately prior to diagnosis. The risk of BMO progressing to bone stress injury during the season was greatest for participants with BMO present 2 weeks prior to the national championship tournament (period of high load) (RR=18.9, OR=44.8). Both bone stress injury and BMO were associated with bowling a higher percentage of days in training and having a shorter bowling break during the season. The number of balls bowled and acute-to-chronic workload were not associated with imaging abnormalities or injury.

Conclusion

The presence of BMO on MRI in asymptomatic junior cricket fast bowlers confers a very high risk for bone stress injury. The risk may be managed by MRI screening and monitoring bowling frequency.
The informal curriculum: what do junior doctors learn from a palliative care rotation?
Authors: Choo Hwee Poi , Hwee Sing Khoo , Yong Hwang Mervyn Koh , Mei Allyn Hum Yin
Published: November 2018

Objectives

Junior doctors learn from the formal and informal curriculum. In a palliative care rotation, the informal curriculum may be useful in teaching attitudes like empathy and compassion. Our study aims to explore how the informal curriculum augments the formal curriculum of a palliative care rotation in shaping the professional development of a doctor.

Methods

We conducted a qualitative study with seven focus group discussions involving 21 junior doctors (medical officers and residents) who spent at least 2 months in a palliative care setting in a tertiary hospital or an inpatient hospice. Data were analysed using qualitative thematic analysis to identify the themes related to the junior doctors' perceptions of how the informal curriculum impacted their humanistic and professional development, thereby augmenting the formal curriculum in a palliative care setting.

Results

Three main themes illustrated how the informal curriculum influenced the doctors: (1) reconceptualisation of control: shifting perspectives as they grappled with their envisioned control versus reality while caring for dying patients; (2) emergence of professionalism: adapting perspectives as they learnt how to bridge theory and reality while developing professionalism and (3) personal growth: forming new perspectives, as doctors reflected on life, death and their calling through a renewed lens.

Conclusion

This study explored how the informal curriculum influenced doctors’ perceptions about professionalism and personal growth, embodying the values of the profession. Observations and interpersonal interactions with healthcare professionals, patients and their caregivers encouraged the doctors to reflect upon their own calling into medicine.
Bulky DNA adducts, microRNA profiles, and lipid biomarkers in Norwegian tunnel finishing workers occupationally exposed to diesel exhaust
Authors: Rynning Iselin , Arlt Volker M , Vrbova Kristyna , Neča Jiří , Rossner Jr Pavel , Klema Jiri , Ulvestad Bente , Petersen Elisabeth , Skare Øivind , Haugen Aage , Phillips David H , Machala Miroslav , Topinka Jan , Mollerup Steen
Published: November 2018

Objectives

This study aimed to assess the biological impact of occupational exposure to diesel exhaust (DE) including DE particles (DEP) from heavy-duty diesel-powered equipment in Norwegian tunnel finishing workers (TFW).

Methods

TFW (n=69) and referents (n=69) were investigated for bulky DNA adducts (by 32P-postlabelling) and expression of microRNAs (miRNAs) (by small RNA sequencing) in peripheral blood mononuclear cells (PBMC), as well as circulating free arachidonic acid (AA) and eicosanoid profiles in plasma (by liquid chromatography–tandem mass spectrometry).

Results

PBMC from TFW showed significantly higher levels of DNA adducts compared with referents. Levels of DNA adducts were also related to smoking habits. Seventeen miRNAs were significantly deregulated in TFW. Several of these miRNAs are related to carcinogenesis, apoptosis and antioxidant effects. Analysis of putative miRNA-gene targets revealed deregulation of pathways associated with cancer, alterations in lipid molecules, steroid biosynthesis and cell cycle. Plasma profiles showed higher levels of free AA and 15-hydroxyeicosatetraenoic acid, and lower levels of prostaglandin D2 and 9-hydroxyoctadecadienoic acid in TFW compared with referents.

Conclusion

Occupational exposure to DE/DEP is associated with biological alterations in TFW potentially affecting lung homoeostasis, carcinogenesis, inflammation status and the cardiovascular system. Of particular importance is the finding that tunnel finishing work is associated with an increased level of DNA adducts formation in PBMC.
Ameliorative effect of low-dose spironolactone on obesity and insulin resistance is through replenishment of estrogen in ovariectomized rats
Authors: Olatunji Lawrence A. , Adeyanju Oluwaseun A. , Michael Olugbenga S. , Usman Taofeek O. , Tostes Rita C. , Soladoye Ayodele O.
Published: November 2018

Women have a lower incidence of cardiovascular diseases (CVD) than men at a similar age but the reverse is the case after menopause, indicating a possible protective effect of estrogen on cardiometabolic function. Although various hormonal therapies have been formulated to combat the CVD risks in postmenopausal state, the beneficial effects have not been consistent. Obesity with insulin resistance (IR) is closely linked to CVD risks while ovariectomized rodents have been shown to mimic a state of obesity and IR. We therefore hypothesized that low-dose spironolactone would ameliorate obesity and IR in estrogen-deprived rats by replenishing estrogen and suppressing elevated glycogen synthase kinase-3 (GSK-3). Ten-week-old female Wistar rats were divided into 4 groups: sham-operated (SHM), spironolactone (SPL; 0.25 mg/kg), and ovariectomized (OVX) rats treated with or without spironolactone daily for 8 weeks. Results showed that estrogen deprivation through ovariectomy caused increased body mass gain and visceral adiposity that are accompanied by increased HOMA-IR, HOMA-β, 1-hour postload glucose, glucose intolerance, platelet/lymphocyte ratio, plasma insulin, atherogenic dyslipidemia, uric acid, GSK-3, corticosterone, and aldosterone and depressed 17β-estradiol. However, treatment of OVX rats with spironolactone ameliorated all these effects. Taken together, the results demonstrate that treatment with low-dose spironolactone improves obesity and IR, which appears to involve replenishment of estrogen and suppression of GSK-3 along with circulating mineralocorticoid and glucocorticoid. The findings imply a positive cardiometabolic effect of low-dose spironolactone usage in estrogen-deprived conditions.
High throughput screening reveals no significant changes in protein synthesis, processing, and degradation machinery during passaging of mesenchymal stem cells
Authors: Sequiera Glen Lester , Sareen Niketa , Sharma Vikram , Surendran Arun , Abu-El-Rub Ejlal , Ravandi Amir , Dhingra Sanjiv
Published: November 2018

Increasing reports of successful and safe application of bone marrow derived mesenchymal stem cells (BM-MSCs) for cell therapy are pouring in from numerous studies. However poor survival of transplanted cells in the recipient has impaired the benefits of BM-MSCs based therapies. Therefore cell product preparation procedures pertaining to MSC therapy need to be optimized to improve the survival of transplanted cells. One of the important ex vivo procedures in the preparation of cells for therapy is passaging of BM-MSCs to ensure a suitable number of cells for transplantation, which may affect the turnover of proteins involved in regulation of cell survival and (or) death pathways. In the current study, we investigated the effect of an increase in passage number of BM-MSCs in cell culture on the intracellular protein turnover (protein synthesis, processing, and degradation machinery). We performed proteomic analysis of BM-MSCs at different passages. There was no significant difference observed in the ribosomal, protein processing, and proteasomal pathways related proteins in BM-MSCs with an increase in passage number from P3 to P7. Therefore, expansion of MSCs in the cell culture in clinically relevant passages (Passage 3–7) does not affect the quality of MSCs in terms of intracellular protein synthesis and turnover.
High transparency flexible sensor for pressure and proximity sensing
Authors: Bu Dan , Li Si Qi , Sang Yun Ming , Qiu Cheng Jun
Published: November 2018

A high-sensitivity and high-transmittance flexible pressure sensor is presented in this paper. Using polydimethylsiloxane (PDMS) sensing film to cover indium tin oxide (ITO) electrodes interdigitated on the polyethylene terephthalate (PET) substrate, an interdigital capacitance (IDC) structure is constructed. The pressure and proximity sensing characteristics of the fabricated IDC sensor are investigated. The experiment results show that the IDC sensor has the piecewise linear function in different pressure range, especially sensitive to the low-pressure range with the pressure sensitivity of 6.64 kPa[Formula: see text]. Moreover, it has a good repeatability with the maximum error rate of 2.73% and a high transmittance over 90% in the wavelength range from 400 nm to 800 nm. As a human finger approaches or leaves, the proximity sensing characteristic emerges, with a maximum sensing distance of about 20 cm.
CRYOGENIC DRILLING OF CARBON FIBER-REINFORCED COMPOSITE (CFRP)
Authors: KOKLU UĞUR , MORKAVUK SEZER
Published: November 2018

In order to reduce the adverse effects on the environment and economy and to avoid health problems caused by the excessively used cutting lubrications, cryogenic machining is drawing more and more attention. In this work, a novel cryogenic machining approach was applied for drilling of carbon fiber-reinforced polymers (CFRPs). According to this approach, CFRP was dipped into the liquid nitrogen (LN2) and it was machined within the cryogenic coolant directly. Various machinability characteristics on thrust force, delamination damage, tool wear, surface roughness, and topography were compared with those obtained with dry condition. This experimental study revealed that the novel method of machining with cryogenic dipping significantly reduced tool wear and surface roughness but increased thrust force. Overall results showed that the cryogenic machining approach in this study improved the machinability of CFRP.
Forecasting the Volatility of Stock Market Index Using the Hybrid Models with Google Domestic Trends
Authors: Seo Monghwan , Lee Sungchul , Kim Geonwoo
Published: November 2018

In order to improve the forecasting accuracy of the volatilities of the markets, we propose the hybrid models based on artificial neural networks with multi-hidden layers in this paper. Specifically, the hybrid models are built using the estimated volatilities obtained from GARCH family models and Google domestic trends (GDTs) as input variables. We further carry out many experiments varying the number of layers and activation functions to obtain the accurate hybrid model for forecasting volatility. The proposed models are applied to forecast weekly and monthly volatilities of S&P 500 index to verify their accuracy. The performance comparison results show that the hybrid models with GDTs outperform clearly the predicted results with GARCH family models and the hybrid models without GDTs in forecasting the volatility of actual market. We also provide the experiment results with graphs to illustrate the efficiency of models.
Tangent bimagnetic curves in terms of inextensible flows in space
Authors: Korpinar Talat
Published: November 2018

In this work, we study inextensible flows of tangent bimagnetic particles in space. Moreover, we obtain the inextensible flows of electric field by Lorentz equation. Finally, we obtain new results for inextensible flows of tangent bimagnetic particles in space.
A new approach for inextensible flows of binormal spherical indicatrices of magnetic curves
Authors: Korpinar Talat , Baş Selçuk
Published: November 2018

In this study, we obtain the special type of magnetic trajectories associated with a magnetic field [Formula: see text] defined on a 3D Riemannian manifold. We investigate a new representation of binormal spherical indicatrices of magnetic curves. Thus, we study [Formula: see text]-magnetic curves terms of inextensible flows. Furthermore, we give some new characterizations of curvatures in terms of some partial differential equations. Finally, we examine some geometrical and physical features of the moving charged particle corresponding to the [Formula: see text]-magnetic curves. Namely, we compute uniformity of the [Formula: see text]-magnetic curves.
Preparation of Well-Dispersed Nanosilver in MIL-101(Cr) Using Double-Solvent Radiation Method for Catalysis
Authors: Chang Shuquan , Liu Chengcheng , Fu Heliang , Li Zheng , Wu Xian , Feng Jundong , Zhang Haiqian
Published: November 2018

In this study, a double-solvent radiation method is proposed to prepare silver nanoparticles in the pores of metal-organic framework MIL-101(Cr). The results reveal that well-dispersed silver nanoparticles with a diameter of about 2[Formula: see text]nm were successfully fabricated in the cages of monodisperse octahedral MIL-101(Cr) with a particle size of about 400[Formula: see text]nm. The structure of MIL-101(Cr) was not destroyed during the chemical treatment and irradiation. The resulting Ag/MIL-101 exhibits excellent catalytic performance for the reduction of 4-nitrophenol. This method can be extended to prepare other single or bimetallic components inside porous materials.
The upGREAT Dual Frequency Heterodyne Arrays for SOFIA
Authors: Risacher C. , Güsten R. , Stutzki J. , Hübers H.-W. , Aladro R. , Bell A. , Buchbender C. , Büchel D. , Csengeri T. , Duran C. , Graf U. U. , Higgins R. D. , Honingh C. E. , Jacobs K. , Justen M. , Klein B. , Mertens M. , Okada Y. , Parikka A. , Pütz P. , Reyes N. , Richter H. , Ricken O. , Riquelme D. , Rothbart N. , Schneider N. , Simon R. , Wienold M. , Wiesemeyer H. , Ziebart M. , Fusco P. , Rosner S. , Wohler B.
Published: November 2018

We present the performance of the upGREAT heterodyne array receivers on the SOFIA telescope after several years of operations. This instrument is a multi-pixel high resolution ([Formula: see text]) spectrometer for the Stratospheric Observatory for Far-Infrared Astronomy (SOFIA). The receivers use 7-pixel subarrays configured in a hexagonal layout around a central pixel. The low frequency array receiver (LFA) has [Formula: see text] pixels (dual polarization), and presently covers the 1.83–2.07[Formula: see text]THz frequency range, which allows to observe the [CII] and [OI] lines at 158[Formula: see text][Formula: see text]m and 145[Formula: see text][Formula: see text]m wavelengths. The high frequency array (HFA) covers the [OI] line at 63[Formula: see text][Formula: see text]m and is equipped with one polarization at the moment (7 pixels, which can be upgraded in the near future with a second polarization array). The 4.7[Formula: see text]THz array has successfully flown using two separate quantum-cascade laser local oscillators from two different groups. NASA completed the development, integration and testing of a dual-channel closed-cycle cryocooler system, with two independently operable He compressors, aboard SOFIA in early 2017 and since then, both arrays can be operated in parallel using a frequency separating dichroic mirror. This configuration is now the prime GREAT configuration and has been added to SOFIA’s instrument suite since observing cycle 6.
A Chance Gardener
Authors: Neville-Neil George
Published: November 2018

It is a very natural progression for a company to go from being a pure consumer of open source, to interacting with the project via patch submission, and then becoming a direct contributor. No one would expect a company to be a direct contributor to all the open-source projects it consumes, as most companies consume far more software than they would ever produce, which is the bounty of the open-source garden. It ought to be the goal of every company consuming open source to contribute something back, however, so that its garden continues to bear fruit, instead of rotting vegetables.
Associations of increased physical performance and change in body composition with molecular pathways of heart disease and diabetes risk
Authors: Kettunen Johannes , Joensuu Anni , Hagnäs Maria , Mikkola Ilona , Wennerström Annika , Lee Joseph H. , Terwilliger Joseph D. , Borodulin Katja , Jousilahti Pekka , Jauhiainen Matti , Jokelainen Jari J. , Keinänen-Kiukaanniemi Sirkka , Perola Markus
Published: November 2018

Higher physical activity is associated with a reduced hazard for a plethora of diseases. It has remained unknown how the two primary physical activity-associated health effects, improved physical performance and change in body composition, independently modulate metabolic profiles toward a reduced risk for adverse outcomes. Here, we utilized a prospective cohort of 664 young men undergoing military service. We studied the metabolic associations of changes in muscle performance and body composition during military service (range 6–12 mo). We subsequently replicated our results for body composition change in 234 population-based samples with a 7-yr follow-up. We found that increased physical performance was associated with reduced very-low-density lipoprotein (VLDL)-related measures [change in VLDL cholesterol: beta = −0.135; 95% confidence interval (CI) = −0.217, −0.054, P = 1.2 × 10−3] and lower inflammation (change in glycoprotein acetyls: beta = −0.138, 95% CI = −0.217, −0.059, P = 6.5 × 10−4), independent of change in body composition. Lower body fat percentage, independent of change in muscle performance, was associated with metabolic changes including lower low-density lipoprotein (LDL) cholesterol measures (change in LDL cholesterol: beta = −0.193, 95% CI = −0.295, −0.090; P = 2.5 × 10−4), increased high-density lipoprotein (HDL) cholesterol measures (change in large HDL cholesterol: beta = 0.316, 95% CI = 0.205, 0.427; P = 3.7 × 10−8), and decreased concentrations of amino acids (change in leucine concentration: beta = −0.236, 95% CI = −0.341, −0.132; P = 1.0 × 10−5) that are type 2 diabetes biomarkers. Importantly, all body fat percentage associations were replicated in a general population-based cohort. Our findings indicate that improved muscle performance showed weaker associations on the metabolic profiles than change in body composition and reduction in body fat percentage reduces cardiometabolic risk mediated by atherogenic lipoprotein particles and branched-chain and aromatic amino acid concentrations.
C60 Fullerene Prevents Restraint Stress‐Induced Oxidative Disorders in Rat Tissues: Possible Involvement of the Nrf2/ARE‐Antioxidant Pathway
Authors: Gonchar Olga O. , Maznychenko Andriy V. , Bulgakova Nataliya V. , Vereshchaka Inna V. , Tomiak Tomasz , Ritter Uwe , Prylutskyy Yuriy I. , Mankovska Iryna M. , Kostyukov Alexander I.
Published: November 2018

The effects of C60FAS (50 and 500 μg/kg) supplementation, in a normal physiological state and after restraint stress exposure, on prooxidant/antioxidant balance in rat tissues were explored and compared with the effects of the known exogenous antioxidant N‐acetylcysteine. Oxidative stress biomarkers (ROS, O2⋅−, H2O2, and lipid peroxidation) and indices of antioxidant status (MnSOD, catalase, GPx, GST, γ‐GCL, GR activities, and GSH level) were measured in the brain and the heart. In addition, protein expression of Nrf2 in the nuclear and cytosol fractions as well as the protein level of antiradical enzyme MnSOD and GSH‐related enzymes γ‐GCLC, GPx, and GSTP as downstream targets of Nrf2 was evaluated by western blot analysis. Under a stress condition, C60FAS attenuates ROS generation and O2⋅− and H2O2 releases and thus decreases lipid peroxidation as well as increases rat tissue antioxidant capacity. We have shown that C60FAS supplementation has dose‐dependent and tissue‐specific effects. C60FAS strengthened the antiradical defense through the upregulation of MnSOD in brain cells and maintained MnSOD protein content at the control level in the myocardium. Moreover, C60FAS enhanced the GSH level and the activity/protein expression of GSH‐related enzymes. Correlation of these changes with Nrf2 protein content suggests that under stress exposure, along with other mechanisms, the Nrf2/ARE‐antioxidant pathway may be involved in regulation of glutathione homeostasis. In our study, in an in vivo model, when C60FAS (50 and 500 μg/kg) was applied alone, no significant changes in Nrf2 protein expression as well as in activity/protein levels of MnSOD and GSH‐related enzymes in both tissues types were observed. All these facts allow us to assume that in the in vivo model, C60FAS affects on the brain and heart endogenous antioxidative statuses only during the oxidative stress condition.
Gas Distribution Law for the Fully Mechanized Top‐Coal Caving Face in a Gassy Extra‐Thick Coal Seam
Authors: Wang Wenlin , Wang Fangtian , Zhao Bin , Li Gang
Published: November 2018

Mine gas overflow is a serious threat to the safe and efficient longwall mining of gassy coal seams. Based on the field mining conditions and gas extraction of the fully mechanized top‐coal caving face of a gassy coal mine, the space volume fraction distribution and emission (extraction rate) of gas in the face were tested by an arrangement of measuring points in the stereo grid. The isograms of gas volume fraction distribution for each measurement section and air direction in the face are drawn. The research shows that each measurement section gas volume fraction distribution is presented for an asymmetric concave curve along the vertical direction of the coal wall in the air‐inlet side and the air‐return side of the face; on the working face air‐return side, the determination of gas volume fraction distribution of the section appears as falling straight line along the vertical direction of the coal wall. Before the first weighting, the absolute quantity of gas emission in the working face increased with the advancing of the working face, reached the maximum at the time of the first weighting, and then remained stable.