bluuebunny/crossref_metadata_2025 huggingface dataset:
Micromechanics of Damage Development in Polymer Composites
Authors: Arabatti Trupti , Sudhir Aswathi , Gururaja Suhasini
Published: February 2016

Damage initiation and progression in uni-directional continuous polymer composites at the microscale has been investigated by considering a 3D Repeating Unit Cell (RUC) with square distribution of fibers. Three damage modes under static loading have been looked at, viz., matrix damage, fiber failure and fiber-matrix debonding. The matrix has been modeled as an isotropic elastic-plastic material via a user material subroutine (UMAT) within the framework of the finite element software Abaqus. In addition, fiber-matrix debonding has been simulated using a traction-separation criterion via Cohesive Zone Modeling (CZM) approach. Finally, a user defined field (USDFLD) has been used to simulate the fiber breakage. The combined effect of matrix-damage, fiber failure and interfacial debonding has then been studied using homogenization principles. Preliminary results from the current modeling approach have been found to be encouraging and this approach paves way for more complex multi-scale damage simulations in heterogeneous materials.
Mechanics of Growing Solids: New Track in Mechanical Engineering
Authors: Manzhirov Alexander V.
Published: February 2016

A vast majority of objects around us arise from some growth processes. Many natural phenomena such as growth of biological tissues, glaciers, blocks of sedimentary and volcanic rocks, and space objects may serve as examples. Similar processes determine specific features of many industrial processes which include crystal growth, laser deposition, melt solidification, electrolytic formation, pyrolytic deposition, polymerization and concreting technologies. Recent researches indicates that growing solids exhibit properties dramatically different from those of conventional solids, and the classical solid mechanics cannot be used to model their behavior. The old approaches should be replaced by new ideas and methods of modern mechanics, mathematics, physics, and engineering sciences. Thus, there is a new track in solid mechanic that deals with the construction of adequate models for solid growth processes. The fundamentals of the mathematical theory of growing solids are under consideration. We focus on the surface growth when deposition of a new material occurs at the boundary of a growing solid. Two approaches are discussed. The first one deals with the direct formulation of the mathematical theory of continuous growth in the case of small deformations. The second one is designed for the solution of nonlinear problems in the case of finite deformations. It is based on the ideas of the theory of inhomogeneous solids and regards continuous growth as the limit case of discrete growth. The constitutive equations and boundary conditions for growing solids are presented. Non-classical boundary value problems are formulated. Methods for solving these problems are proposed.
Pressure Wave Propagation in a Bubbly Medium: A Multiscale Modelling Approach
Authors: Kapahi Anil , Hsiao Chao-Tsung , Chahine Georges L.
Published: February 2016

This work uses a compressible Eulerian multi-material solver with three modeling approaches to examine shock and pressure wave propagation in a bubbly medium. These approaches represent different levels of complexity from fully resolving the dispersed bubbles to treating the bubbly medium as a homogeneous mixture. An intermediate approach is based on treating bubbles as discrete singularities. Propagation of the pressure wave through the bubbly medium is compared between the simplified approaches and the fully resolved bubble simulation. Different scenarios demonstrating the effect of pressure amplitude, void fraction, and bubble size distribution are presented to further understand wave propagation in bubbly media.
High Cycle Fatigue Strength of Modified 9Cr-1Mo Steel at Elevated Temperatures
Authors: Ochi Motoyuki , Suzuki Ken , Nonaka Isamu , Miura Hideo
Published: February 2016

In order to clarify the characteristics of high-cycle fatigue of the modified 9Cr-1Mo steel, a high temperature rotary bending test was carried out. As a result, the fatigue strength of this alloy decreased monotonically at elevated temperatures. It decreased from 440 MPa at room temperature to about 350 MPa at 400°C. This decrease of the fatigue strength was attributed to the temperature dependence of the yielding strength of this alloy. The fatigue limit appeared near 107 cycles at 400°C, whereas it appeared around 106 cycles at room temperature. The most important result is that the fatigue limit disappeared up to 108 cycles at temperatures higher than 500°C. Thus, the number of cycles at which the fatigue limit appeared shifted to higher cycles with increasing the testing temperature. Clear striation was observed in the stable crack growth region on the fracture surface of all the specimen tested at room temperature, 400°C, 500°C, 550°C, and 600°C. Intergranular cracking, which have been observed in creep-fatigue tests, was not observed. Since the estimated operating temperature of FBR is 550°C, it is very important to consider this fatigue strength in the structural and reliability design of the modified 9Cr-1Mo steel.

In this study, the change of crystallinity of this alloy under fatigue loading was also analyzed by applying an EBSD method. The image quality (IQ) value obtained from the analysis was used for the quantitative evaluation of the crystallinity in the area where an electron beam of 20 nm in diameter was irradiated. The quality of the atomic alignment was found to degrade under the cyclic loading, and a crack started to occur on the surface of the alloy when the quality of the atomic alignment decreased to a certain critical value.
Analytical Stiffness Modeling and Experimental Validation for a Pneumatic Artificial Muscle
Authors: Leclair Justin , Doumit Marc , McAllister Greg
Published: February 2016

Since the introduction of assistive technologies for enhancing human mobility, there has been a high demand for compact, lightweight, powerful and energy efficient actuator. The Pneumatic Artificial Muscle (PAM) is a distinctive compliant pneumatic actuator, which has properties similar to the biological skeletal muscle, making it a great candidate for applications in human mobility assistive devices. Whereas the PAMs can be used actively or passively, until now, it has been mostly used in active applications to power various mechanisms, such as robotic arms, most notably the Shadow Robot Company Dextrous hand. For those applications, static and dynamic models of PAM have been developed by researchers to fairly accurately predict the muscle-force carrying capabilities and muscle contraction distance behavior, respectively. However, limited passive models have been developed, with results varying from acceptable to poor in terms of accuracy. Recognizing the significance of characterizing the PAM passive behavior, especially for legged locomotion application, this paper proposes a PAM stiffness model that is based on Newtonian mechanics and considers geometric, mechanical and material properties of the muscle. The proposed stiffness model is experimentally validated for a wide range of operating conditions.
Electrospinning of Cisplatin-Loaded Cellulose Nanofibers for Cancer Drug Delivery
Authors: Absar Saheem , Khan Mujibur , Edwards Kyle , Calamas David
Published: February 2016

Cellulosic nanofibers have been electrospun with an antitumor agent Cisplatin. Cellulose acetate (CA) and Cisplatin were co-electrospun using a coaxial electrospinning system. For the outer sheath, a solution of 7.5wt% CA in Acetone and DMAc (2:1) was used. The inner core consisted of Cisplatin dissolved in DMF at a concentration of 5mg/ml. Drug-loaded nanofibers from Cellulose pulp (2wt%) dissolved in NMMO. H2O were also produced. The solutions were electrospun in a high voltage electric field of 25–30 kV. Characterization of neat and drug-loaded nanofibers was performed using Scanning electron microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The characterization studies have shown the formation of nanofibers having both sporadic beads with internal agglomeration and conjugation of Cisplatin on the nanofiber surfaces.
Mechanical Properties of Monolayer Molybdenum Disulfide
Authors: Tabarraei Alireza , Wang Xiaonan , Shadalou Shohreh
Published: February 2016

We use atomistic simulations to study mechanical properties of monolayer molybdenum disulfide MoS2. Using molecular dynamic (MD) simulations, we investigate the nano-fracture properties of monolayer MoS2 under mixed mode I and II loadings. The MD simulations are used to obtain the critical stress intensity factors of both armchair and zigzag cracks as a function of applied loading phase angle. Our atomistic simulations predict that armchair cracks are tougher than zigzag cracks, and both armchair and zigzag cracks tend to propagate along a zigzag path. Furthermore, we use density functional theory (DFT) to investigate how point defects influence the mechanical properties of nanoribbons. Our DFT simulations show that missing one S atom does not significantly affect the mechanical strength of monolayer MoS2, whereas missing one Mo atom can reduce the maximum strength of single layer MoS2 sheet by about 10%.
Evaluation of Fatigue Strength of AISI 4340 Steel Under Hydrostatic Pressure
Authors: Prakash Raghu V. , Raphael Deepak C.
Published: February 2016

The presence of hydrostatic pressure in the range of 10 to 600 bar (typical of sea depths from 100 meters to 6 kilometers) and cyclic wave loading in off-shore structures and equipments operating in deep-water environment requires suitable criteria accounting for high hydrostatic load during design of such structural elements. The presence of corrosive species due to sea water and marine organisms also adds complexity to this problem. Plain fatigue data evaluated under ambient conditions or fatigue data evaluated in atmospheric conditions under soaked sea water environment may not be appropriate for the design of systems subjected to hydrostatic pressure. High hydrostatic pressure alters the yield criterion of materials. Thus, it becomes essential to generate the fatigue strength data of structural steel in pressurized simulated sea water (3.5% NaCl solution) conditions.

This paper presents the comparison of fatigue life data evaluated for a structural steel material under ambient conditions and under hyperbaric pressure conditions. A special hyperbaric chamber was designed for this purpose and 3.5% NaCl solution was pressurized into the chamber by a manual pump. Mechanical fatigue loading was applied on the specimen in the presence of two pressures, viz., 30 bar and 50 bar hydrostatic pressure. The results suggest that hydrostatic pressure has a significant influence on fatigue life data of steel. The fracture surfaces were examined using a scanning electron microscope which suggests change in fracture mode from being pure ductile to mixed mode of fracture. Work is in progress to evaluate the strength degradation of welded joints subjected to hyperbaric fatigue.
Experimental Study of Energy Absorption of Fluid-Filled Honeycomb Structure
Authors: Jenson S. , Ali M. , Alam K. , Hoffman J.
Published: February 2016

The work presented here is a continuation of the study performed in exploring the energy absorption characteristics of non-Newtonian fluid-filled regular hexagonal aluminum honeycomb structures. In the previous study, energy absorbing properties were investigated by using an air powered pneumatic ram, dynamic load cell, and a high speed camera. This study was conducted using a pneumatic ram which was designed to exploit only its kinetic energy during the impact. Experimental samples included an empty honeycomb sample and a filled sample as the filled samples showed the largest difference in energy absorption with respect to the empty samples in the previous study. Therefore, the filled samples were further investigated in this study by measuring the impact forces at the distal end as well as the damage on the impact end. Upon impact, the filled samples were able to reduce the damage area on impact end and were able to lower average and peak forces by 71.9% and 77.4% at the distal end as compared to the empty sample.
Analysis of a Diesel Engine Exhaust Manifold
Authors: Yang Yiran , He Miao , Mojtahed Masoud
Published: February 2016

The exhaust manifold is an essential component of an engine, which has become increasingly important because of innovations in the industry. Thus, the efficiency of an exhaust manifold is a key factor in overall engine efficiency. In operating conditions, there are many factors that may influence the performance of an exhaust manifold, such as temperature, pressure, wall thickness, coolant velocity, etc.

A manufacturer of diesel engine’s exhaust manifolds was interested in investigating the performance of its manifolds. This paper describes the method of analysis and results obtained by Fluent and ANSYS software. The purpose of the project is to analyze the stress distribution and locate the areas most prone to failure.
In-Situ SEM Testing for Transient Fatigue Crack Growth Behavior Investigation Subjected to a Single Tensile Overload
Authors: Zhang Wei , Liu Yongming
Published: February 2016

In this paper, the in-situ scanning electron microscopy (SEM) experiments are performed in the edge-cracked specimen under the single overload in order to investigate transient fatigue crack growth behavior. The specimen is made of Al7075-T6 and under the plane stress condition. During the testing, several loading cycles of interest are selected and divided into a certain number of steps. At each step, high resolution images around the crack tip region are taken under the SEM. Imaging analysis is used to quantify the crack tip opening displacement (CTOD) at each corresponding time instant in a loading cycle. In the current experimental work, the crack closure phenomenon is not only directly observed under constant amplitude loadings, but also under the variable amplitude loading. The experimental results provide the evidence that the crack closure may disappear or become inconsequential right after the single overload. And some observations imply that the crack closure is not the only parameter which controls fatigue crack growth rate, other factors need to be considered. A detailed discussion is given based on the current investigation.
Microcapsules Containing Solvent and Epoxy With Multi-Walled Carbon Nanotubes for Self-Healing
Authors: Phamduy Paul , Kim Byungki
Published: February 2016

Microcapsules containing epoxy resin EPON 862, phenyl acetate solvent, and multi-walled carbon nanotubes were fabricated by in-situ polymerization for the development of a self-healing composite. The microcapsules were embedded in an epoxy matrix in single-edged notch bend shapes for fracture testing on a three-point bend test fixture. Healing efficiency was calculated for specimens with various microcapsule loading ratios. Fracture tests confirmed healing ability with the microcapsules. Preliminary results indicated higher healing efficiencies with increased microcapsule loading.
Delamination Behavior of Laminated Paper
Authors: Suda Mitsunori , Wang Wei , Kitamura Takanori , Ito Kanta , Wada Kenji , Zhang Zhiyuan , Yang Yuqiu , Hamada Hiroyuki
Published: February 2016

Paper recycling is an effective way in reducing deforestation and energy consumption. Therefore recycling paper and paper products has been widely applied in many areas, such as packaging industry, furniture decoration, temporary structures in building and so on. Paper products are made from plant fibers and they are laminated materials. So it is of possible to generate interlaminar fracture in the use of paper products, especially in the construction made of paper such as paper tubes which have been used widely. In order to improve the interlaminar performance of paper products and then improve the construction performance of paper products, delamination behavior of laminated paper has been studied in this paper. By a series of peel tests, comparative analysis about different paperboard were carried out. The cause of delamination behavior of laminated paper was analysis based on the detailed observation using a scanning electron microscope (SEM).
Static and Dynamic Friction Characteristics of a Steel on Polyoxymethylene Interface Under Dry and Lubricated Contact Conditions
Authors: Larson Matthew G. , Timpe Shannon J.
Published: February 2016

The static and dynamic friction characteristics of a steel pin on injection molded polyoxymethylene homopolymer disk system were studied under both lubricated and dry contact conditions. Samples were tested at externally-applied normal loads ranging from 20 to 160 N. Under dry test conditions, friction coefficients displayed two distinct regions with very low friction coefficients at low loads and rising to approximately 0.7 (static) and 0.6 (dynamic) at loads above 60N. This phenomenon is attributed to an enhanced contribution of the ploughing friction mechanism at higher loads. As load increases, the pin penetrates through the injection mold-induced skin layer and into the core. At loads lower than 60 N, however, the pin does not significantly penetrate the disk during the test and the adhesive mechanism dominates the tribological properties. Additional tests were performed in order to determine the effects of a lithium soap thickened, low viscosity, synthetic hydrocarbon grease. The average static and dynamic friction coefficients for the lubricated interface were found to be 0.031 ± 0.01 and 0.027 ± 0.01, respectively. The friction coefficients exhibited a linear dependence on the load. This result indicates a shift from the more optimal elastohydrodynamic lubrication regime at lower loads to a mixed lubrication regime and a behavior closer to dry contact at higher loads. Results are interpreted in light of the principal static and dynamic friction mechanisms.
Exact 3-D Stress and Stiffness Analysis of Functionally Graded Sandwich Plates Using Sampling Surfaces Method
Authors: Darabi Mehdi , Ganesan Rajamohan
Published: February 2016

In the present work, the three-dimensional analysis for the deflection and stress distributions of functionally graded ceramic–metal sandwich plates is developed based on the method of sampling surfaces (SaS). In accordance with this method, into each layer of the plate, reference surfaces that are not equally spaced and are parallel to the mid-surface of the plate are introduced, and the displacement vectors of these surfaces are chosen as unknown functions. Such a choice allows the representation of the governing equations of the proposed higher order layer-wise plate theory in a very compact form and also permits the derivation of strain–displacement relationships correctly describing all motions including the rigid-body motions of the functionally graded plate. Hence the 3D elasticity problem of the thick plate is efficiently solved. The material properties of sandwich plate’s face layer are assumed to be that of a two-constituent material that vary continuously through the thickness of the face sheet according to a power law distribution of the volume fraction of the constituents. The core layer is homogeneous and made of an isotropic ceramic material. The effects of the volume fraction of the material constituents and their distribution on the deflections and, in particular, the 3-D stress distributions as well as the effects of the length-to-width and length-to-thickness ratios of the plate are investigated. Comparison of the results of the present work with the results available in existing literature is carried out for a benchmark problem. It is shown that considering large number of SaS, which are located at interfaces and Chebyshev polynomial nodes, the accuracy of the solutions can be improved significantly wherein the error will approach zero value as the total number of surfaces in each layer become very large.
Lattice Thermal Conductivity of Fe-Cr Alloys With 〈001〉 Tilt Boundaries: An Atomistic Study
Authors: Shabib Ishraq , Abu-Shams Mohammad , Khan Mujibur R.
Published: February 2016

The objective of this study is to examine lattice thermal conductivity (κ) of Fe-Cr alloys containing different 〈001〉 tilt grain boundaries (GBs). The effects of Cr concentration (2 and 10%) and three different 〈001〉 tilt boundaries (Σ5{310}, Σ13{510}, and Σ17{530}) have been examined at 70K using the reverse non-equilibrium molecular dynamics (rNEMD) simulation technique. The results exhibit higher κ for Fe or Fe-Cr models with Σ5[310] GB. The values are 2–4% and 12–16% more than those of models with Σ13[510] and Σ17[530] GBs, respectively. Pure Fe single crystal models exhibit higher conductivities than Fe/Fe-Cr models with various Σ tilt boundaries. κ decreases 7–9% as GBs are introduced into the pure Fe single crystal models. On the other hand, the conductivities of Fe-Cr models are affected more by the Cr concentration than the presence of a particular GB. As 10% Cr is added into the system the conductivity decreases by 7.6–9.4% compared to the pure Fe models.
Environment Analysis Near a Highway Using Computational Fluid Dynamics
Authors: Zhuang Xinwei , Wang Xiuling
Published: February 2016

Air pollution has been proven as a significant risk factor for multiple health conditions. A major portion of urban air pollution is attributed to vehicle emissions. In this study, a high school which is close to an interstate highway is numerical simulated to estimate the impact of traffic emissions on air quality. Two probability density functions, Weibull distribution and Rayleigh distribution, were used in wind data statistical analysis. A numerical method was used to estimate the wind speed at study site based on the wind data in meteorology stations. Both indoor and outdoor environment were simulated using computational fluid dynamics (CFD). The airflow and the dispersion of particulate air pollutants emitted from the highways surrounding the high school building were analyzed. The wind flow was simulated using Reynolds-Averaged Navier Stokes (RANS) model. The particulate matters are tracked using Lagrangian model. For the indoor simulation, the standard k-ε model is employed to model the air-phase turbulence. Discrete phase model (DPM) and Eulerian multiphase model were utilized for the particle phase, respectively. The comparison shows that the Lagrangian approach has better agreement since the dispersed-phase volume fractions are less than 10%.
Numerical Modeling of Braided Composites Using Energy Method
Authors: Shen Xiuli , Gong Longdong
Published: February 2016

Based on the braiding process and force analysis of yarn, a mesoscopic numerical modeling approach was established, which divided the modeling process as follows: establishing the control points according to the braiding process, establishing the fixed points during jamming, adjusting the control points after jamming, changing the position of fiber bundle due to the fiber bundle intertwined each other and establishing the fiber bundle trajectory according to the minimum strain energy. In the process of adjusting the intertwined fiber bundle trajectories, the fiber bundle trajectory was scattered. Using extrapolation adjustment method, discrete points of fiber bundle trajectory intertwined were adjusted in turn from the control points to the fixed points. Adjusted discrete points were equivalent at the corresponding location points of the corresponding trajectory, and at the same time, there was non-interference between the fiber bundle trajectories. Using this method, fiber bundle trajectory and cross section of the models of 2-D woven and 3-D four-directional braided composite materials were established, compared with the experiment result, which were consistent with the electronic microscope scan images and calculated woven structure size was in agreement with the measured data. The maximum relative calculation error of braiding bitch of 3-D four-directional braided structure was about 5%, especially braiding angle was 21° or so, the relative calculation error was below 2%. The maximum relative calculation error of surface braiding angle of 3-D four-directional braided structure was about 4%, especially braiding angle was 21° or so, the relative calculation error was below 2.4%. This modeling approach was fundamental for further analysis of the micromechanical strength and life of braided composites, which was applied to aero-engine hot section.
A Multiscale Model to Determine the Stiffness of Collenchyma Tissue in Rheum Rhabarbarum
Authors: Faisal Tanvir R. , Hristozov Nicolay , Western Tamara , Rey Alejandro , Pasini Damiano
Published: February 2016

The stiffness of plant tissue largely influences the overall mechanical response of plant organs, such as stems, branches and leaf petioles. This work examines the structural hierarchy of the plant tissue; in particular of the collenchyma tissue of the Rheum rhabarbarum. The goal of the paper is to develop a multiscale model capturing features of two orders of its structural hierarchy: cell wall and tissue architecture. The former is considered as a fiber reinforced composite, where the cellulose microfibril (CMF) is the main load bearing component. The longitudinal stiffness of the middle (S2) layer of the secondary cell wall is affected by the microfibril angle (MFA) up to 45° to a greater extent, which in turn plays a role in the overall wall stiffness. The latter, i.e. tissue architecture, influences the tissue stiffness through its random distribution of cells. Finite-edge Centroidal Voronoi Tessellation (FECVT) is used to model the non-periodic microstructure of the rhubarb collenchyma, whose effective elastic properties are obtained through finite element analysis. The results from the FECVT model show that the effective stiffness in the longitudinal direction is 15 to 25% higher than that in the transverse direction for relative density between 5 and 30%. The variation reflects the stiffening effect of the shape and size of the cells in the collenchyma tissue, as well as its aperiodic cellular distribution.
The Role of Multiscale Strain Localizations in Fatigue of Magnesium Alloys
Authors: Cuadra Jefferson , Hazeli Kavan , Cabal Michael , Kontsos Antonios
Published: February 2016

The reliable characterization of fatigue behavior and progressive damage of advanced alloys relies on the monitoring and quantification of parameters such as strain localizations as a result of both crystallographic deformation mechanisms and bulk response. To this aim, this article attempts to directly correlate microstructural strain at specific fatigue life to global strain as well as surface roughness in Magnesium alloys. Strain at the grain scale is calculated using Digital Image Correlation (DIC), while surface topography gradients are computed using roughness data at different stages of the fatigue life. The results are further correlated to Electron Back Scatter Diffraction (EBSD) measurements which reveal the profuse and spatially inhomogeneous nature of the crystallographic deformation mechanisms related to yielding and fatigue crack initiation. Emphasis is given on using multimodal NDE data to formulate first a description of the current state of the material subjected to fatigue loading and on identifying conditions that can probabilistically drive the affected by both local and global response, governing degradation process.
A Crystallographic Approach to Life Prediction Analysis of a Turbine Engine Blade to Disk Attachment
Authors: Naboulsi Sam
Published: February 2016

Fretting fatigue raises many challenges in modeling and predicting of a turbine engine blade disk attachment response. It occurs when the blade and disk are pressed together in contact and experience a small oscillating relative displacement due to variations in engine speed and vibratory loading. Fretting causes a very high local stress near the edge of contact resulting in wear, nucleation of cracks, and their growth, which can result in significant reduction in the life of the material. Fretting depends on geometry, loading conditions, residual stresses, nonlinear response, and surface roughness, among other factors. These complexities make fretting a significant driver of fatigue damage and failure risk of disks. That is, fretting is often the root cause of the nucleation of cracks at attachments of structural components, and the cyclic plastic cumulative deformation and damage occur within depths of only several grains. Hence, resolving the deformation at the scale of individual grains, in order to understand the crystallographic orientation dependence of plasticity driven fretting fatigue and its relation to surface contact conditions, is important. In this study, a finite strain computational crystal plasticity constitutive law will be implemented to simulate and investigate time dependent response of turbine engine blade to disk attachment. The present work leverages the computational model of early efforts, which focused on modeling damage initiation and propagation due to fretting fatigue using micro-thermo-mechanical model, and further enhances the capabilities of capturing the micro-scale nature of the fretting small oscillatory relative displacement at grain level. These efforts provided a high fidelity approach to capture the life of the material at the blade to disk attachment and to simulate the realistic mechanism associated with fretting.
Optimization of AC Electrokinetic Mixing by Nanocomposite Monolayer
Authors: Islam Nazmul
Published: February 2016

The mixing of fluids using AC Electrokinetic is presented in this paper. Both AC electrothermal (ACET) and AC electroosmosis (ACEO) techniques are investigated for mixing operation. AC electrokinetic mixing utilizes the characteristics of short diffusion distance and large specific interface area, and the characteristics of laminar flow and multiphase flow in a microchannel. The proposed mixer will have advantages of easy implementation and compatibility with microchip fabrication. Furthermore low and high conductive fluid has been experimented for mixing operation. In this research, the ACET and ACEO mixing will be optimized by surface modification using a biocompatible hydrophobic nanocomposite monolayer. This coating will modify the mixer surface to a hydrophobic surface and improve the friction losses at the interface, and eventually increase the mixing rate. Both ACEO and ACET flow is a promising technique in microfluidic mixing toward laboratory automation applications, such as clinical diagnostics and high-throughput drug screening. But the mixing efficiency and type of AC electrokinetic usage depends on the conductivity range of the fluids. These mixers can be integrated with the lab-on-a-chip and can provide inexpensive disposable devices.
Live From Nassau Mausoleum: Reactive Strategies at a Major Sports Arena
Authors: Hirshon Nicholas , Davis Craig
Published: February 2016

Nassau Veterans Memorial Coliseum, a sports and entertainment arena in Long Island, New York, encountered a public relations challenge in the 1990s. Nassau Coliseum, one of a few high-capacity venues in the New York metropolitan area, hosted the New York Islanders of the National Hockey League and concerts featuring headliners such as the Grateful Dead, New Kids on the Block, and Frank Sinatra. Nevertheless, the arena became a target for the world’s first all-sports radio station, WFAN 660 AM in New York City. WFAN hosts perpetuated the image of a dreary “Nassau Mausoleum” with dim lighting, long bathroom and concession lines, and a leaky roof. By placing students in the decision-making situation that confronted the Nassau Coliseum executives, this case explores various approaches to reputation management at sports venues.
ONC201: Stressing tumors to death
Authors: Endo Greer Yoshimi , Lipkowitz Stanley
Published: February 2016

Two studies find that the small molecule ONC201 induces cancer cell death through cellular stress–related pathways.
Overcoming immunotherapy resistance
Authors: Ferrarelli Leslie K.
Published: February 2016

PTEN deficiency in tumors suppresses immunosurveillance by increasing production of inhibitory cytokines and decreasing autophagy.
Acupuncture for Fibromyalgia in Primary Care: A Randomised Controlled Trial
Authors: Vas Jorge , Santos-Rey Koldo , Navarro-Pablo Reyes , Modesto Manuela , Aguilar Inmaculada , Campos M Ángeles , Aguilar-Velasco José Francisco , Romero Milagrosa , Párraga Patricia , Hervás Vanesa , Santamaría Olalla , Márquez-Zurita Carmen , Rivas-Ruiz Francisco
Published: February 2016

Objectives

To evaluate the efficacy of an individualised acupuncture protocol for patients with fibromyalgia.

Methods

Randomised controlled multicentre trial, blinded to participants and to data analysts. Conducted in three primary care centres in southern Spain. A total of 164 participants aged over 17 years and diagnosed with fibromyalgia were enrolled in this trial; 153 participants completed the study. Participants were randomly assigned to either the real intervention (individualised acupuncture, IA) or the sham intervention (sham acupuncture, SA). In both the IA and SA groups, one session per week (lasting 20 min) was provided, in addition to usual pharmacological treatment. The primary outcome was change in pain intensity at 10 weeks.

Results

Intention-to-treat analysis revealed that the decrease in pain intensity at 10 weeks was greater (p=0.001) in the IA group (−41.0%, 95% CI −47.2% to −34.8%) than in the SA group (−27.1%, 95% CI −33.2% to −20.9%). During the follow-up period, significant differences (p<0.01) in favour of the IA group persisted at 12 months (IA: −19.9%, 95% CI −24.6% to −15.1%; vs SA: −6.2%, 95% CI −11.2% to −1.2%).

Conclusions

Individualised acupuncture treatment in primary care in patients with fibromyalgia proved efficacious in terms of pain relief, compared with placebo treatment. The effect persisted at 1 year, and its side effects were mild and infrequent. Therefore, the use of individualised acupuncture in patients with fibromyalgia is recommended.

Trial Registration Number

ISRCTN60217348.
Spontaneous pituitary apoplexy during the second trimester of pregnancy, with sensory loss
Authors: Abraham Rtika R , Pollitzer Rachel E , Gokden Murat , Goulden Peter A
Published: February 2016

A 32-year-old Hispanic woman at 23 weeks gestation presented with right-sided headache, associated with photophobia and right-sided numbness. She denied visual problems, menstrual irregularities and galactorrhoea. Examination revealed visual acuity 20/40 bilaterally with some blurriness on the left side, decreased right V1-V2 facial sensation and preserved 5/5 power, but decreased sensation over the entire right upper extremity (RUE) and right lower extremity (RLE) to touch and pinprick. Laboratories suggested normal pituitary function, but MRI of the brain revealed enlargement of the pituitary (1.7 cm), with layering haemorrhage posteriorly and mild compression of the optic nerve. The patient underwent emergent evacuation of a pituitary haematoma, and histology revealed minute fragments of adenohypophysis with haemorrhage and fibrosis.
Long-standing meningomyelocele can be a predictor of difficult airway and postoperative hypoventilation: challenge to the anaesthesiologist
Authors: Sardar Arijit , Khanna Puneet , Singh Abhishek , Sharma Ankur
Published: February 2016

A 15-year-old female patient presented with severe pain in the abdomen and obstructive uropathy. She underwent Yang-Monti ileovesicostomy under general anaesthesia. She is a known case of long-standing meningomyelocele (MMC) and presented with its potential complications such as difficult airway and restrictive lung disease. We describe the successful anaesthetic management of a case of anticipated difficult airway and postoperative hypoventilation as a sequel of kyphosis due to MMC. Her airway was secured with fibre optic-guided intubation in a semirecumbent position. Postoperative hypoventilation, hypercarbia and respiratory acidosis were managed conservatively, followed by staged weaning in the intensive care unit. Obstruction of the catheterisable continent channel of the neurogenic bladder itself may present with uropathy and urosepsis, which were also taken care of preoperatively.
Introduction of a simple guideline to improve neurological assessment in paediatric patients presenting with upper limb fractures
Authors: Marsh Andrew G , Robertson James S , Godman Anna , Boyle Jennifer , Huntley James S
Published: February 2016

Background

Neurological examination in children presenting with upper limb fractures is often poorly performed in the Emergency Department (ED). We aimed to assess the improvement in documented neurological examination for children presenting with upper limb fractures following introduction of a simple guideline.

Methods

We developed and introduced a simple guideline for upper limb neurological assessment in children (‘rock, paper, scissors, OK’). We compared documentation of neurological examination and nerve injury detection at our hospital before and after introduction of this guideline, as well as for children admitted from external hospitals (where the guideline had not been introduced).

Results

In the period following guideline introduction, 97 children with upper limb fractures were admitted (46% presenting directly to our ED and 54% admitted from external hospitals). This cohort was similar in number and distribution to the cohort reviewed prior to the guideline. Documentation of neurological examination in our ED increased from 92% to 98% after guideline introduction. Documented information on nerves examined also increased from 2% to 68% (p<0.01). Prior to the guideline, there were six nerve injuries, all of which were missed in our ED. After guideline introduction, there were four nerve injuries, all of which were detected in our ED. Documentation and nerve injury detection at external hospitals over the same time period showed no improvement.

Conclusions

A simple guideline to assist neurological examination in children with upper limb fractures can significantly improve the quality of documented neurological assessment and nerve injury detection.
Why people don’t use family planning: how different methods of enquiry elicit different responses
Authors: Bisits-Bullen Piroska , Phiri Precious , Chirwa Sam , Chauwa Lloyd
Published: February 2016

Background

Engaging community, government and non-governmental organisation (NGO) stakeholders in the design of family planning (FP) programmes is best practice. Stakeholders can provide local insights on barriers to FP. However, it can be difficult to know whether there may be limited programme perceptions if only one method of enquiry is used.

Aim

This study aimed to validate the perceptions of stakeholders on barriers to FP in Malawi.

Methods

The study was conducted in a rural area in Lilongwe District, Malawi and employed a mixed-methods exploratory design. Five focus groups were run with community, government and NGO stakeholders to identify barriers to using modern FP. The results of the qualitative phase were then compared using a quantitative survey of 960 women who had at least one child aged under 5 years.

Results

The qualitative phase identified a range of barriers to FP, including lack of awareness, lack of access, religious beliefs, myths, and opposition by husbands. However, the quantitative survey found that these issues are not a concern for the majority of women. The main reasons given by women for not using FP were that were not currently having sex or had a child recently, and so they felt they did not need to use it.

Conclusions

Perceptions of stakeholders from a qualitative approach do not necessarily reflect the perspectives of the population as documented in a quantitative survey. When involving stakeholders it is important to recognise that different approaches may elicit different responses, particularly with regard to sensitive issues or issues that apply to particular subgroups. Consequently, a deeper understanding is likely to be obtained by using a multimethod approach.
Computational fluid dynamics analysis of flow reduction induced by flow-diverting stents in intracranial aneurysms: a patient-unspecific hemodynamics change perspective
Authors: Ouared Rafik , Larrabide Ignacio , Brina Olivier , Bouillot Pierre , Erceg Gorislav , Yilmaz Hasan , Lovblad Karl-Olof , Mendes Pereira Vitor
Published: February 2016

Background and purpose

Flow-diverter stents (FDSs) have been used effectively to treat large neck and complex saccular aneurysms on the anterior carotid circulation. Intra-aneurysmal flow reduction induces progressive aneurysm thrombosis in most patients. Understanding the degree of flow modification necessary to induce complete aneurysm occlusion among patients with considerable hemodynamics variability may be important for treatment planning.

Materials and methods

Patients with incidental intracranial saccular aneurysms who underwent FDS endovascular procedures were included and studied for a 12 months’ follow-up period. We used computational fluid dynamics on patient-specific geometries from 3D rotational angiography without and with virtual stent placement and thus compared intra-aneurysmal hemodynamic problems. Receiver operating characteristic analysis was used to estimate the stent:no-stent minimum hemodynamic ratio thresholds that significantly (p≤0.05) determined the condition necessary for long-term (12 months) aneurysm occlusion.

Results

We included 12 consecutive patients with sidewall aneurysms located in the internal carotid or vertebral artery. The measured porosity of the 12 deployed virtual FDSs was 83±3% (mean±SD). Nine aneurysms were occluded during the 12 months’ follow-up, whereas three were not. A significant (p=0.05) area under the curve (AUC) was found for spatiotemporal mean velocity reduction in the aneurysms: AUC=0.889±0.113 (mean±SD) corresponding to a minimum velocity reduction threshold of 0.353 for occlusion to occur. The 95% CI of the AUC was 0.66 to 1.00. The sensitivity and specificity of the method were ∼99% and ∼67%, respectively. For both wall shear stress and pressure reductions in aneurysms no thresholds could be determined: AUC=0.63±0.16 (p=0.518) and 0.67±0.165 (p=0.405), respectively.

Conclusions

For successful FDS treatment the post-stent average velocity in sidewall intracranial aneurysms must be reduced by at least one-third from the initial pre-stent conditions.
Cardiac function associated with previous, current and repeated depression and anxiety symptoms in a healthy population: the HUNT study
Authors: Gustad L T , Bjerkeset O , Strand L B , Janszky I , Salvesen Ø , Dalen H
Published: February 2016

Objective

Symptoms of anxiety and depression often co-exist with cardiovascular disease (CVD), yet little is known about the association with left ventricular (LV) subclinical dysfunction. We aimed to study the cross-sectional associations of previous, current and repeated depression or anxiety symptoms, with sensitive indices of LV systolic and diastolic function, based on tissue Doppler (TD) and speckle tracking (ST) imaging methods.

Methods

A random selection of 1296 individuals free from known CVD, hypertension and diabetes were examined with echocardiography at baseline of the third Nord-Trøndelag Health Study, (HUNT3, 2006–2008). The primary outcomes were LV diastolic function (e′) and LV systolic function (longitudinal global strain). The primary exposures were self-report on the Hospital Anxiety and Depression Scale (HADS). Associations between outcomes and baseline exposures were available for 1034 (80%), and with previous and repeated exposures for 700 participants who also participated in HUNT2 (1995–1997).

Results

Previous and repeated depression symptoms, but not current depression, were linearly associated with a reduction in e′. The average sum of two repeated HADS-D scores 10 years apart had the strongest effect on e′ (−8.3%; 95% CI −13.9% to −2.7%) per 5 units. We observed a sex difference between depression symptoms and longitudinal global strain (p for interaction 0.019), where women had a marginal negative effect. Anxiety symptoms, neither previous, current nor repeated were associated with subclinical LV dysfunction.

Conclusions

In a healthy sample, confirmed free of CVD, past and repeated depression symptoms were associated with subclinical LV dysfunction. Thus, depression symptoms might represent a modifiable risk factor for future CVD.
Volume-equated high- and low-repetition daily undulating programming strategies produce similar hypertrophy and strength adaptations
Authors: Klemp Alex , Dolan Chad , Quiles Justin M. , Blanco Rocky , Zoeller Robert F. , Graves B. Sue , Zourdos Michael C.
Published: February 2016

The overarching aim of this study was to compare volume-equated high-repetition daily undulating periodization (DUPHR) versus a low-repetition daily undulating periodization (DUPLR) program for muscle performance. Sixteen college-aged (23 ± 3 years) resistance-trained males were counterbalanced into 2 groups: (i) DUPHR (n = 8), with a weekly training order of 12 repetitions (Day 1), 10 repetitions (Day 2), and 8 repetitions (Day 3); and (ii) DUPLR (n = 8), with a weekly training order of 6 repetitions (Day 1), 4 repetitions (Day 2), and 2 repetitions (Day 3). Both groups trained 3 times/week for 8 weeks on nonconsecutive days, with pre- and post-training testing during weeks 1 and 8. Participants performed only squat and bench press exercises each session. Changes in one-repetition maximum (1RM) strength, muscle thickness (MT), and muscular endurance (ME) were assessed. Both groups significantly increased 1RM strength for both squat and bench press (p < 0.01), and no group differences existed (p > 0.05). Similarly, both groups experienced significant increases in chest, lateral quadriceps distal, and anterior quadriceps MT (p < 0.05), but no change was present in either group for lateral quadriceps mid MT (p < 0.05). No group differences were discovered for changes in MT (p > 0.05). ME did not significantly change in the squat or bench press for either group (p > 0.05); however, for squat ME, a moderate effect size was observed for DUPHR (0.57) versus a trivial effect size for DUPLR (0.17). Our findings suggest that in previously trained males, training volume is a significant contributor to strength and hypertrophy adaptations, which occur independently of specific repetition ranges.
Identification ofBacillus megateriumandMicrobacterium liquefaciensgenes involved in metal resistance and metal removal
Authors: Fierros-Romero Grisel , Gómez-Ramírez Marlenne , Arenas-Isaac Ginesa E. , Pless Reynaldo C. , Rojas-Avelizapa Norma G.
Published: February 2016

Bacillus megaterium MNSH1-9K-1 and Microbacterium liquefaciens MNSH2-PHGII-2, 2 nickel- and vanadium-resistant bacteria from mine tailings located in Guanajuato, Mexico, are shown to have the ability to remove 33.1% and 17.8% of Ni, respectively, and 50.8% and 14.0% of V, respectively, from spent petrochemical catalysts containing 428 ± 30 mg·kg−1Ni and 2165 ± 77 mg·kg−1V. In these strains, several Ni resistance determinants were detected by conventional PCR. The nccA (nickel–cobalt–cadmium resistance) was found for the first time in B. megaterium. In M. liquefaciens, the above gene as well as the czcD gene (cobalt–zinc–cadmium resistance) and a high-affinity nickel transporter were detected for the first time. This study characterizes the resistance of M. liquefaciens and B. megaterium to Ni through the expression of genes conferring metal resistance.