bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Cellulosic and Basic Flux on the Structure, Composition and Hardness of SMAW Welds on Steel X42
Authors: Khamouli Farida , Zidani Mosbah , Farh Hichem , Saoudi Adel , Atoui L'Hadi
Published: December 2016

This paper studied the effects of cellulosic and basic flux on the chemical composition, microstructure, formation of inclusions and micro hardness of X42 steel SMAW welds. The commercialized chemical compositions of flux used are: E6010, E8010-P1 and E8018-G, with electrodes of low carbon content. Welding conditions are not constant. The microstructure of the fusion zone for each flux consists mainly of acicular ferrite. It is found that manganese increases in the fusion zones (C, B and A) respectively .The change in mass concentration of manganese is homogeneous through the three points with all the used flux. Regardless of the flux used, the non-metallic inclusions observed are of two types: white and black. The micro-hardness decreasing values were obtained in the fusion zones (C, B and A).
Modelling, Simulation and Sensitivity Analysis of a Fatty Acid Methyl Ester Reactive Distillation Process Using Aspen Plus
Authors: Anene Refiner Chikere , Giwa Abdulwahab
Published: December 2016

Reactive distillation, being an intensified process of combining reaction and distillation in a single vessel, is an ongoing research. This work considered the use of this novel process to investigate how the purity of a fatty acid methyl ester (oleic acid methyl ester – methyl oleate), which is an alternative fuel that has a potential economic bedrock, vary with variations in reflux ratio and reboiler duty with the aid of Aspen Plus model of the process. The column employed in developing the model of the process was a RadFrac type having 29 stages, which was divided into five sections, namely condenser (top), rectifying, reaction, stripping and reboiler (bottom) sections. After the development, the model was simulated using UNIversal QUAsiChemical model (UNIQUAC) base method. In order to investigate the sensitivity of the system, reflux ratio and reboiler duty were varied from 2.0-5.5 and 1350-1800 W, respectively. The results obtained from the steady-state simulation of the process revealed that the developed Aspen Plus model of the system was table because it was able to converge when simulated. Furthermore, it was discovered from the sensitivity analysis carried out that a methyl oleate having a mole fraction of approximately 0.7627 could be obtained from the process when the reflux ratio and the reboiler duty were 2.0 and 1800 W respectively. Also, it was observed that the mole fraction of methyl oleate was sensitive to both reflux ratio and reboiler duty because the variations in them (reflux ratio and reboiler duty) resulted in corresponding variation in the methyl oleate mole fraction obtained from the system.
Study the Relation between Flow, Thermal and Mechanical Properties of Waste Polypropylene Filled Silica Nanoparticles
Authors: Hadi Nizar Jawad , Mohamed Dhey Jawad
Published: December 2016

This paper investigates the flow, thermal and mechanical properties of waste polypropylene (WPP) reinforced with silica (SiO2) nanoparticles (NPs). Recently the researches prove that the addition of NPs to the thermoplastic polymer produces significant change in its properties. SiO2 NPs of 0.001, 0.003, 0.006, 0.009, 0.012 and 0.015wt% were mixed with the WPP using twin screw extruder. The mixing process performed at 10 rpm and 190°C. The topography and particle size distribution of 0.001, 0.006 and 0.015 of SiO2 NPs concentrations samples are analyzed using atomic force microscopy (AFM). The crystallinity of nanocomposite was examined by X-ray diffraction. The melt flow rate (MFR) and melt volume rate (MVR) are tested due to SiO2 NPs concentration at standard condition using melt flow index (MFI) device. The shear viscosity and melt density are calculated using MFR and MVR values. Differential Scanning Calomitry (DSC) is used to show the effect of SiO2 NPs concentration on the thermal history of nanocomposite. Charpy impact strength and hardness are tested. The results show that the MFR and MVR increase with the NPs concentration increasing. The shear viscosity decreases with MFR and MVR increasing. The crystallinity level and the crystallinity temperature decreases with SiO2 NPs concentration increasing while impact and hardness increasing. Clear difference between solid and melt density is observed. There is a compatible between the thermal, flow and mechanical properties of different SiO2 nanocomposite samples.
Influence of Precursor Solution Concentration on Structure and Magnetic Properties of Zinc Oxide Thin Films
Authors: Sindhu H.S. , Joishy Sumanth , Rajendra B.V. , Babu P.D.
Published: December 2016

Zinc oxide thin films were deposited on glass substrate at a substrate temperature of 673K by spray pyrolysis method using different concentration of 0.0125M, 0.025M and 0.05M of Zinc acetate solutions. The effect of molar concentrations on structure, surface morphology and magnetic properties of ZnO films were investigated using x-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. All deposited films were polycrystalline in nature with hexagonal wurtzite structure having a preferential growth orientation along (101) plane. An improvement of crystallinity in the deposits with increasing concentration of sprayed solution was noticed. All deposit exhibit fibrous structure which increases with increase of precursor concentration solutions. At room temperature, all deposited films were shown diamagnetic character but when cooled to 5K, they have shown paramagnetic characteristics.
Surface Morphology and Corrosion Behavior in Nano PMEDM
Authors: Abdul-Rani Ahmad Majdi , Nanimina Alexis Mouangue , Ginta Turnad Lenggo
Published: December 2016

This research study was conducted to investigate the effect of nanoaluminum powder mixed electrical discharge machining (PMEDM) on surface morphology and corrosion rate of titanium alloy material. The development of devices such as implants in biomedical engineering application nowadays requires materials having good mechanical and physical properties. Conventional machining process of titanium as implant is a challenge resulting relative poor surface quality. Even using electrical discharge machining (EDM) which is non-conventional machining process there are limitations including machined surface alteration with relative poor machined surface quality, low corrosion resistance and. PMEDM is hypothesized to address the above mentioned problems. In this study, PMEDM on titanium alloy using nanoaluminum powder and copper-tungsten electrode was assessed to investigate the improvement for implant application. Process parameters used are peak-current, ON-time, gap voltage and powder concentration. Surface morphology and average corrosion arte are selected output responses. Results showed that Surface morphology of PMEDM machined surface is significantly improved. PMEDM marginally enhanced corrosion rate of biomedical grade titanium alloy.
Seismic Performance of a Concrete Highway Tunnel under Earthquake Sequence Using a Concrete Damage Plasticity Model
Authors: Dulinska Joanna M. , Murzyn Izabela J.
Published: December 2016

The aim of this paper was to investigate the dynamic response of a concrete tunnel subjected to mainshock–aftershock seismic sequence. Three components of the registered seismic saquence were applied as seismic excitation acting in three directions. A three-dimensional FE model of a tunnel section (600 m long) was prepared with the ABAQUS software. The soil layers interacting with the tunnel lining were also taken into consideration. To represent the inelastic behavior of the concrete material under the earthquakes, a concrete damage plasticity model (CDP) was assumed a constitutive model for the concrete. The analysis proved that strongly nonlinear behaviour of the concrete lining of the tunnel was observed under the sequence of seismic events. The plastic strains as well the tensile damage (cracking) were noticed in some zones of the concrete lining after the first and the second event. The crack patterns were in good agreement with damages observed on concrete tunnels during real earthquakes. The results indicate that aftershocks can enlarge zones affected by irreversible strains or cause damage evolution. The analysis also revealed that aftershocks, even being much weaker than main events, may result in additional loss of concrete material strength while performing in mainshock-aftershock seismic sequences and striking a structure which is already degraded by a mainshock.
Characterization of Hardening Behavior at Ultra-High Strain Rate, Large Strain, and High Temperature
Authors: Piao Ming Jun , Huh Hoon , Lee Ik Jin
Published: December 2016

This paper is concerned with the characterization of the OFHC copper flow stress at strain rates ranging from 10−3 s−1 to 106 s−1 considering the large strain and high temperature effects. Several uniaxial material tests with OFHC copper are performed at a wide range of strain rates from 10−3 s−1 to 103 s−1 by using a INSTRON 5583, a High Speed Material Testing Machine (HSMTM), and a tension split Hopkinson pressure bar. In order to consider the thermal softening effect, tensile tests at 25°C and 200°C are performed at strain rates of 10−3 s−1,101 s−1, and 102 s−1. A modified thermal softening model is considered for the accurate application of the thermal softening effect at high strain rates. The large strain behavior is challenged by using the swift power law model. The high strain rates behavior is fitted with the Lim–Huh model. The hardening curves are evaluated by comparing the final shape of the projectile from numerical simulation results with the Taylor impact tests.
A Simulation of Ferroelastic Phase Formation by Using Phase Field Model
Authors: Muramatsu Mayu , Kawada Tatsuya , Terada K.
Published: December 2016

In order to incorporate the mechanical behavior of ferroelastic phase into the stress analysis of solid oxide fuel cell in consideration of elastic, creep, thermal and reduction strains, we propose a mathematical model to predict the formation of ferroelastic phases in crystal grains of La0.6Sr0.4Co0.2Fe0.8O3-δ. The phase field model equipped with the elastic energy is introduced to realize the morphology formation of ferroelastic phases in a crystal grain. By the use of the developed mathematical model, some numerical examples are performed to reproduce the deformation-induced nucleation and growth of ferroelastic phases of La0.6Sr0.4Co0.2Fe0.8O3-δ.
Macroscopic Yield Function Predicted by Crystal Plasticity Simulation on Ultrafine-Grained Aluminum
Authors: Aoyagi Yoshiteru
Published: December 2016

In this study, using experiment results obtained by electron backscatter diffraction, information on crystal orientation is introduced into a computational model for crystal plasticity simulation considering the effects of grain boundaries and dislocation sources to express the effect of the microstructure of ultrafine-grained metals. Finite-element simulations are performed for a polycrystal of an aluminum plate under biaxial tension. The multiscale crystal plasticity simulations depict the yield surface of the ultrafine-grained aluminum produced by accumulative roll-bonding processes. The anisotropic material coefficients of a higher-ordered yield function for ultrafine-grained aluminum are derived using a genetic algorithm.
Crystal Plasticity Analysis of Mechanical Response in Two Phase Alloys with Dispersion of Fine Particles
Authors: Ohashi Tetsuya , Okuyama Yelm
Published: December 2016

Macroscopic mechanical responses of alloy steels dispersed with fine vanadium carbide particles [1] were analyzed by crystal plasticity finite element method. Average distance of dispersed particles was used as a microscopic length scale and introduced to the models of the critical resolved shear stress and the mean free path of dislocations. Numerical result of yield stress agreed well with that of experimental result [1], but that of the work hardening rate was slightly higher than that of experimental one. When the dislocation mean free path was set to be 2 to 3 times the average spacing of dispersed particles, the work hardening rate fit better with the experimental one.
Advances in Constitutive Modeling of Plasticity for Forming Applications
Authors: Barlat Frédéric , Jeong Youngung , Ha Jin Jin , Tomé Carlos , Lee Myoung Gyu , Wen Wei
Published: December 2016

A succinct description of advanced constitutive models for applications to forming process simulations is provided. These models are continuum-based because they are more efficient in terms of computation time than microstructure–based models. However, they are so–called advanced because they are considered in many scientific studies but rather scarcely used in industrial applications. In addition, the relationship between these continuum constitutive models and multi-scale approaches based on crystal plasticity, dislocation dynamics and mechanics of multi-phase materials, such as advanced high strength steels, is substantiated.
An Improved Thermo-Ratcheting Boundary of Pressure Pipeline
Authors: Kan Qian Hua , Li Jian , Jiang Han , Kang Guo Zheng
Published: December 2016

The thermal ratcheting boundary of pressure pipeline is a popular topic in nuclear power engineering. The existed thermal ratcheting boundary based on the Bree diagram is conservative for structures subjected to the thermo-mechanically coupled loadings since it was obtained only from an elastic-perfectly plastic model. Therefore, it is necessary to improve the existed thermal ratcheting boundary based on a reasonable constitutive model. The Bree diagram was validated firstly by the linear relationship between the plastic strain increment and mechanical stress by finite element method. And then the influences of different constitutive models, such as elastic-perfectly plastic, multi-linear kinematic hardening, Chaboche and Abdel Karim-Ohno models, on the thermal ratcheting boundary of pressure pipeline were investigated numerically. It is found that the elastic-perfectly plastic and multi-linear kinematic hardening models provide the lower and upper bounds for the thermal ratcheting boundary, respectively. Finally, an improved thermal ratcheting boundary by introducing the dimensionless axial tensile stress was proposed based on the Bree diagram, the improved thermal ratcheting boundary covered the present cases with different ratios of mechanical stress over thermal stress.
Fatigue of Extruded 2017A Aluminum Alloy Subjected to Non-Proportional Loading Paths
Authors: Allaoui Omar , Taleb Lakhdar , Brik Mouaad , Keller Clément , Marnier Gael
Published: December 2016

The present work is devoted to the study of the fatigue of an extruded aluminum alloy 2017A under cyclic loading in axial and shear directions at room temperature. Having the lifetime under a given axial amplitude σa (say, Nf_a) and the lifetime under a given torsional amplitude τa (say, Nf_t) [1], the objective here is to evaluate the lifetime when σa and τa are applied successively according to non-proportional path: σa then τa then σa then τa and so on until the fracture of the specimen. The obtained lifetime Nf_np is then compared to (Nf_a / 2 + Nf_t / 2). The obtained results point out the importance of the loading magnitude. Microstructural analyses have been performed to better understand the fracture mechanisms for the different cases of loadings.
Calculation Strategy for the Determination of Plasticity Correction Factors
Authors: Du Juan , Shao Xue Jiao , Kan Qian Hua , Zhang Ying , Fu Xiao Long
Published: December 2016

This paper presents an investigation about the plasticity correction factor, Ke, proposed in the RCCM code, for correction of the elastic stress ranges exceeding twice the yield stress, resulting from both mechanical and thermal loading. The plasticity correction factors are analyzed using a calculation strategy based on a comparison between results from linear elastic and elastoplastic analyses. The RCC-M code provides the codified expressions of Ke and material parameters for general materials of nuclear components, but there are no expressions and material parameters for the new material. Several elastoplastic models, geometries and loading types are considered in the study based on the general material listed in RCCM code to determine the calculation strategy for the determination of Ke for new material. Based on the results, the determination of Ke expressions and parameters for Titanium Alloy is discussed. The proposed Ke factor of Titanium Alloy has been determined and delivered the same sufficiently conservative results. An exemplary verification calculation of general materials that have been performed and the conservative allowance is obtained.
On the Choice of the Power Law Flow Rule and its Consequences in Crystal Plasticity
Authors: Chowdhury Helal , Altenbach Holm , Naumenko Konstantin
Published: December 2016

Three types of power law flow rules are commonly used in classical crystal plasticity. These laws are purely phenomenological. The foremost point is how to define operative or effective stress and drag or slip system resistance. Specific choice of the definition leads to a unique number of implications including lattice rotation and slip activities, and we will highlight a few of them. We examined these three flow rules within finite strain framework with a single crystalline Al-rich TiAl binary alloy at very high homologous temperature with three strain rate controlled experimental data . It is revealed that two internal variables based flow rules give better results with a wide variety of applicability in plasticity and related phenomena.
Failure Criteria of Adhesive Joints between Aluminum Circular Pipes under Multiaxial Stress State
Authors: Tanaka Hiro , Kimura Mayuko , Iimori Masato , Shibutani Yoji , Liu Yang
Published: December 2016

In this study, we developed a new conceptual test method of adhesive joining using aluminum circular pipes with sloping bonded surfaces to evaluate the failure strength of the adhesive layer under a multiaxial stress state. In our experiment, we prepared several test specimens made of A5052 aluminum with cross-sectional surfaces possessing angles of inclination varying from 0–90 degrees. We then carried out uniaxial tensile tests, employing paired aluminum pipe halves joined by adhesives. From the load‒displacement curves, we estimated the first invariant of the stress tensor and the second invariant of the deviatoric stress tensor, and we applied two kinds of criteria, both of which effectively represent the failure stress of the adhesive joint. According to the failure criteria, the thickness-dependent strength of the adhesive layer and its power law are discussed.
Two-Scale Analysis of Thermal Behavior of CFRP Laminates Based on a Thermoelastoviscoplastic Homogenization Theory
Authors: Matsuda Tetsuya , Toyomura Jin , Ogaki Tsubasa , Arai Masahiro
Published: December 2016

In this study, a two-scale thermoelastoviscoplastic analysis method for carbon fiber-reinforced plastic (CFRP) laminates is proposed based on a homogenization theory for time-dependent composites. For this, macroscopic and microscopic boundary value problems for CFRP laminates are derived to discuss the relation between the two problems. Using the relation, a two-scale thermoelastoviscoplastic analysis method is constructed, and then applied to the analysis of thermal behavior of an unsymmetric cross-ply carbon fiber/epoxy laminate. The laminate is subjected to a macroscopic temperature change from 180°C to 20°C. It is shown that quite high residual stress and strain occur both macroscopically and microscopically in the laminate, resulting in large macroscopic warpage of the laminate.
A New Algorithm of the Boundary Restraining Force for One-Step Inverse Analysis
Authors: Bao Yi Dong , Qin Xue Jiao , Cui Jing , Wang Hui Ting
Published: December 2016

In one-step inverse analysis, the restraining force produced by blank holder and draw bead need to be replaced equivalently by the nodal force to obtain a rational blank shape. But the distribution of the equivalent restraining force should not be uniform. A self-adaptive algorithm of the equivalent restraining force is presented in this paper. By comparing the initial configration contour line of the part obtained from three different methods (self-adaptive algorithm, uniformly distributed algorithm and a commercial software Fastform) with experimental results, the self-adaptive algorithm is proved to be accurate and convenient.
Influence of Dog-Bone Width on End Profile in Plan View Pattern Control Method for Plate Rolling
Authors: Horie Masayuki , Hirata Kenji
Published: December 2016

A plan view pattern control method for plate rolling called Mizushima Automatic Plan View Pattern Control System (MAS) or Dog Bone Rolling (DBR) was developed. In this method, the slab is given a non-uniform thickness profile in the width direction to obtain non-uniform elongation. In order to make the plate more rectangular under various rolling conditions, prediction of elongation is necessary. In this research, the influence of the dog-bone width (overly thick part at the slab width edge) on the fish-tail length (over-elongation at the slab end) is investigated. The fish-tail length increases as the dog-bone width increases in spite of the same dog-bone height. This phenomenon is related to the following behavior of the restriction of excessive elongation of the dog-bone: As the dog-bone width increases, the working length of restricting stress increases. Hence, restricting stress is released earlier and the rolling length for fish-tail formation increases. As a result, the fish-tail length increases. Therefore, for the prediction of plan view pattern, not only the dog-bone thickness, but also the dog-bone width should be considered.
The Numerical Simulation of Multi-Stage Sheet Metal Forming Based on Modified Yoshida-Uemori Hardening Model
Authors: Chen Jiang , Chen Wen Liang
Published: December 2016

Bauschinger effect is significant for metal forming, particularly for aluminum. A material constitutive model especially for multi-stage sheet metal forming is presented in this paper, which is improved based on Yoshida-Uemori(Y-U) model assumes that there exists different coefficient on equivalent back stress and boundary surface between stages. The prediction of this model is validated through real tension and compression test. Compared to other hardening rules, it can be shown that a more accurate result can be predicted by this model. This model is also successfully applied to be used in the numerical simulation of a multi-stage manufacturing process of an A-pillar, the experimental result demonstrates the advantage of this model in springback analysis in multi-stage simulation over other constitutive model.
Wear Mechanism and Ability for Recovery of Tool Steel on Blanking Die Process
Authors: Lawanwong Komgrit , Pumchan Wichai
Published: December 2016

Tool steel grade JIS; SKD-11 is a well-known raw material for making a high wear resistance of blanking tool in stamping industry. One problem in the blanking process is the high cost of raw material for making punch and die. Therefore, in this study, behavior of wear phenomenon and ability of recycle on the punch of blanking die process were investigated. In the first section, phenomenon and mechanism wear of blanking punch were observed. We found that mechanism of wear on blanking punch was adhesion wear, since high amount of chromium content in the punch has compatibility of elements. The second section, recovery punch was designed by annealing, resize and quenching process by using the new punch from the first section. From the recovery punch results, it was found that the wear resistance of recovery punch decreased slightly but it was strong enough to continue in blanking process. However, the recycle process of tool steel depends on a quality and amount of the product.
A Yield Function for Anisotropic Sheet Material Described by 3rd-Degree Spline Curve and its Applications
Authors: Aamaishi Toshiro , Tsutamori Hideo , Iizuka Eiji , Sato Kentaro , Ogihara Yuki , Matsui Yohei
Published: December 2016

A new plane stress yield function using the 3rd-degree spline curve is proposed for the anisotropic behavior of sheet metals. This yield function considers the evolution of anisotropy in terms of both r values and stresses. In order to demonstrate the applicability of the proposed yield function, hole expanding tests with mild steel and 6000 series aluminum alloy sheets were simulated.
Elastic Modulus Model Based on Dislocation Density and its Application on Aluminum Alloy 5052
Authors: Yu Hai Yan , Zhou Chen Xiao
Published: December 2016

An elastic modulus model is proposed to describe the phenomenon of the material’s elastic modulus varying with plastic strain. This elastic modulus model is theoretically interpreted using the dislocation density as an internal variant. Loading-unloading-reloading (LUR) tensile tests have been implemented to analyze the non-linear unloading behavior. The maximum decrease of the elastic modulus of AA5052 is approximately 16%. The proposed model is introduced into the springback simulation of U-bending. The results showed that the contour of springback simulation with the proposed elastic modulus model is closer to that of the experimental data than results of constant elastic modulus simulation. Error in the springback simulation with the proposed elastic modulus model can be reduced by up to 20% compared with that predicted with a constant elastic modulus.
Friction Stir Forming of Aluminum Alloy Gear-Racks
Authors: Ohashi Takahiro , Chen Jia Zhao , Nishihara Tadashi , Tabatabaei Hamed Mofidi
Published: December 2016

Friction-stir-forming (FSF) of gear-racks of JIS A5083 aluminum alloy is reported in this paper. We put a material plate on a gear-rack die and conducted friction stirring on its back surface. The material deformed and precisely filled the fine cavity of the die due to high pressure and heat caused by friction stirring. This study investigates the forming conditions and the corresponding results, including the material fill ratio in the tooth. It is thought that the deformation volume of the material is key for the fill ratio, and the shoulder diameter of the tool in a single-pass process or the path area in a multi-pass process affects it as well.
Optimum Design of Si-Cr Alloy Springs for Seismic Vibration Isolator
Authors: Chen Dyi Cheng , Kao Shih Hung , Chen Li Ren , Wang Sheng Jung , Chen Chih Yuan , Huang Chen Kun
Published: December 2016

In this paper, a dynamic stress analysis of seismic vibration isolator was carried out by using ANSYS. The vibration isolator consisted of Si-Cr springs and magnetorheological dampers. The stress and deformation of the springs were calculated when an impact load was applied to the isolator. From the simulation for six different springs, in terms of their wire dimeter and coil diameter, an optimum shape of the springs to minimize the stress and deformation was determined.
Preventive Neuromuscular Training for Young Female Athletes: Comparison of Coach and Athlete Compliance Rates
Authors: Sugimoto Dai , Mattacola Carl G. , Bush Heather M. , Thomas Staci M. , Foss Kim D. Barber , Myer Gregory D. , Hewett Timothy E.
Published: December 2016

Context: Fewer athletic injuries and lower anterior cruciate ligament injury incidence rates were noted in studies of neuromuscular-training (NMT) interventions that had high compliance rates. However, several groups have demonstrated that preventive NMT interventions were limited by low compliance rates.

Objective: To descriptively analyze coach and athlete compliance with preventive NMT and compare the compliance between study arms as well as among school levels and sports.

Design: Randomized, controlled clinical trial.

Setting: Middle and high school athletic programs.

Participants or Other Participants: A total of 52 teams, comprising 547 female athletes, were randomly assigned to the experimental or control group and followed for 1 athletic season.

Intervention(s): The experimental group (n = 30 teams [301 athletes]: 12 basketball teams [125 athletes], 6 soccer teams [74 athletes], and 12 volleyball teams [102 athletes]) participated in an NMT program aimed at reducing traumatic knee injuries through a trunk-stabilization and hip-strengthening program. The control group (n = 22 teams [246 athletes]: 11 basketball teams [116 athletes], 5 soccer teams [68 athletes], and 6 volleyball teams [62 athletes]) performed a resistive rubber-band running program.

Main Outcome Measure(s): Compliance with the assigned intervention protocols (3 times per week during the preseason [mean = 3.4 weeks] and 2 times per week in-season [mean = 11.9 weeks] of coaches [coach compliance] and athletes [athlete compliance]) was measured descriptively. Using an independent t test, we compared coach and athlete compliance between the study arms. A 2-way analysis of variance was calculated to compare differences between coach and athlete compliance by school level (middle and high schools) and sport (basketball, soccer, and volleyball).

Results: The protocols were completed at a mean rate of 1.3 ± 1.1 times per week during the preseason and 1.2 ± 0.5 times per week in-season. A total of 88.4% of athletes completed 2/3 of the intervention sessions. Coach compliance was greater in the experimental group than in the control group (P = .014). Coach compliance did not differ by sport but was greater at the high school than the middle school (P = .001) level. Athlete compliance did not differ by study arm, sport, or school level.

Conclusions: Athletes received instruction in about 50% of each protocol. Nearly 90% of athletes performed more than 2/3 of the assigned NMT interventions. The assigned intervention was performed more often in the experimental arm compared with the control arm. Coaches at the high school level complied with the given protocol more than middle school coaches did. Athletes complied well with the protocol, but coaches did not, especially at the middle school level.
Twisted Alexander Invariants Detect Trivial Links
Authors: Friedl Stefan , Vidussi Stefano
Published: December 2016

It follows fromearlier work of Silver andWilliams and the authors that twisted Alexander polynomials detect the unknot and theHopf link. We now show that twisted Alexander polynomials also detect the trefoil and the ûgure-Ç knot, that twisted Alexander polynomials detect whether a link is split and that twisted Alexander modules detect trivial links. We use this result to provide algorithms for detecting whether a link is the unlink, whether it is split, and whether it is totally split.
Influence of the Number of Bleaching Sessions on Fracture Resistance and Dentin Microhardness of Endodontically Treated Teeth
Authors: Bandeca Matheus Coelho , Kuga Milton C , Jordão-Basso Keren CF , Tonetto Mateus R , Lima Suellen L , Garrido Lorena DMA , Kalatzis-Sousa Natália G , Dantas Andrea AR , Leonardo Renato DT
Published: December 2016

Objectives

To evaluate the effects of number of bleaching sessions on fracture resistance and dentin microhardness in endodontically treated teeth using 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) associated to light emitting diode (LED)—laser system.

Materials and methods

Forty human incisors were endodontically treated and divided according to the number of bleaching sessions (n = 10, each group): G1 — no treatment G2 — one; G3 — two; and G4 — three sessions. The 15HPTiO2 was applied within the pulp chamber and on the buccal surface, then photoactivated using LED—laser. All experimental specimens were restored with ionomer glass cement between each session and in the final treatment. Specimens were then subjected to the fracture resistance test (kN), using an electromechanical machine. To the dentin microhardness evaluation, 40 crown extracted endodontically treated human teeth were longitudinally sectioned, divided into groups as previously described (n = 10), and submitted to similar bleaching protocol. Dentin microhardness was evaluated before and after the final dental bleaching session in each group using Knoop indentator. Data were analyzed by analysis of variance (ANOVA) and Tukey tests (p = 0.05).

Results

The fracture resistance values were similar among all groups (p > 0.05). The number of dental bleaching sessions had a negative influence on the microhardness dentin, because G4 > G3 > G2 > G1 (p < 0.05).

Conclusion

The number of bleaching sessions using 15% hydrogen peroxide with titanium dioxide nanoparticles associated to LED—laser system had no influence on the fracture resistance of the endodontically treated teeth crowns, but promoted a reduction in dentin microhardness.

How to cite this article

Garrido LDMA, Kuga MC, Kalatzis- Sousa NG, Dantas AAR, Tonetto MR, Leonardo RDT, Jordão- Basso KCF, Lima SL, Borges AH, Bandeca MC. Influence of the Number of Bleaching Sessions on Fracture Resistance and Dentin Microhardness of Endodontically Treated Teeth. World J Dent 2017;8(1):5-9.
Compliance with Statutory Tobacco Guidelines in and around Schools in Mangaluru, India: An Observational Study
Authors: Rajesh G , Priyanka Ravi , Rao Ashwini , Ramya Shenoy , Mithun Pai BH
Published: December 2016

Context

Tobacco is the foremost cause of preventable death and disease in the world today, and India is the second largest consumer of tobacco products in the world. The Cigarettes and Other Tobacco Products Act (COTPA) promulgated in 2003 by the Government of India, not only mandates ban on the sale of tobacco within a 100-yard radius around schools, but also provides guidelines for tobacco-free schools.

Aim

To determine if the provisions of the COTPA are being complied with, in Mangaluru, India.

Materials and methods

A cross-sectional study was conducted among 30 randomly selected schools in Mangaluru, India. Information was collected regarding sale of tobacco at vendor locations within 100-yard radius of these schools. An interview schedule was administered to the representative of the school, pertaining to the guidelines for tobacco-free schools.

Statistical analysis used

The data were coded and analyzed using the Statistical Package for Social Sciences (SPSS) version 11.5. The level of statistical significance was kept at p < 0.05.

Results

There were 48 shops located within 100-yard radius of the schools, out of which 46 (95.8%) sold single cigarettes but only one shop displayed surrogate advertisement. Among the 30 schools surveyed, only 3 (10%) displayed signages prohibiting smoking. Although the guidelines for tobacco-free schools explicitly state that all schools must have a copy of the COTPA, only 3 (10.0%) schools maintained a copy.

Conclusion

This study showed that there was a widespread violation of Section 6 of the COTPA 2003 in Mangaluru, India.

How to cite this article

Priyanka R, Rao A, Rajesh G, Ramya S, Mithun PBH. Compliance with Statutory Tobacco Guidelines in and around Schools in Mangaluru, India: An Observational Study. World J Dent 2017;8(1):10-13.
Factors determining Radiation Protection Practices among Indian General Dental Practitioners: An Explorative Study
Authors: Binnal Almas , Rajesh Gururaghavendran
Published: December 2016

Introduction

Radiation exposure encountered in dentistry is minimal; however, their harmful effects cannot be ruled out. Though there are several guidelines established to minimize exposure to X-rays in dentistry, earlier studies have reported that practitioners are not entirely compliant with the same. There is, therefore, a definite need to identify factors that influence compliance with radiation protection practices among general dental practitioners (GDPs).

Objective

The objective is to assess various factors influencing radiation protection practices among Indian GDPs.

Materials and methods

A cross-sectional study design using a pretested, self-administered, structured questionnaire comprising of 37 items was employed in the present study. Information pertaining to demographics and radiation protection practices among GDPs was collected.

Results

A total of 66.7 and 49.4% did not follow position and distance rule respectively; overall, 88.5 and 94.3% did not use lead apron and thyroid collar respectively, for their patients. It was observed that 60.9% did not adjust exposure parameters according to tooth position; a total of 94.2% did not use personal dosimeters, while 63.2% disposed radiographic waste in common drain. Correlation analysis revealed significant association of awareness about governing bodies with educational course, distance rule with years of practice, personal dosimeter usage with gender, and other patients’ exposure to radiation with type of practice of the participants (p < 0.05).

Conclusion

The present study revealed poor radiation protection practices among GDPs. Low compliance with personnel- and patient-related protection measures was observed. A majority of the respondents were not familiar with radiation protection guidelines. Correlation analysis revealed important demographics that were influencing radiation protection practices among the respondents. The present study highlights crucial policy implications to ensure greater compliance with appropriate radiation protection guidelines among GDPs in India.

How to cite this article

Binnal A, Rajesh G, Ahmed J, Denny C. Factors determining Radiation Protection Practices among Indian General Dental Practitioners: An Explorative Study. World J Dent 2017;8(1):14-20.
Persistence of Residues after Endodontic Retreatment related to the Obturation Technique and to the Solvent
Authors: Bandéca Matheus Coelho , Kuga Milton C , Jordão-Basso Keren CF , Tonetto Mateus R , Aranda-Garcia Arturo J , Vázquez-Garcia Fernando A , Lima Suellen NL , Monteiro Jardel C do Carmo
Published: December 2016

Objective

To quantify the persistence of residues after endodontic retreatment related to the root canal obturation technique (lateral compaction or single cone) previously performed and the solvent used (xylol or Endosolv-R) in the cervical and root apical segment using digital radiograph.

Materials and methods

Forty root canals were prepared using the F2 instrument and filled with gutta-percha and AH Plus, 20 canals using #25 point by lateral compaction and the other 20 using F2 point by single cone. The root canals were transversely sectioned, and two segments (cervical and apical) were obtained. Radiographs were taken from the segment in buccolingual and mesiodistal direction, as well as the area that was originally filled with the root canal obturation was measured using ImageJ. After the specimens were set on special devices, the obturations were removed using the rotary system and divided into four groups (n = 10): G1 — lateral compaction and xylol; G2 — lateral compaction and Endosolv-R; G3 — single cone and xylol; and G4 — single cone and Endosolv-R. A new radiograph was taken and the area occupied by residues was measured. The persistence of residues was obtained from the obturation remaining in the root canal in percentage. The data were analyzed using Kruskal—Wallis test (p = 0.05).

Results

There was no difference among the examined groups, regardless of the radicular segment or the radiograph direction (p > 0.05).

Conclusion

The endodontic retreatment using xylol or Endosolv-R in the obturations previously performed by lateral compaction or single cone technique presented similar persistence of residues in the root canal, regardless of the radicular segment.

How to cite this article

Aranda-Garcia AJ, Kuga MC, Vázquez-Garcia FA, Tonetto MR, Bandeca MC, Lima SNL, Freitas J, Borges AH, Jordão-Basso KCF, do Carmo Monteiro JC. Persistence of Residues after Endodontic Retreatment related to the Obturation Technique and to the Solvent. World J Dent 2017;8(1):41-44.
Smoking influences the Occurrence of Radiodermatitis in Head and Neck-irradiated Patients
Authors: Kuga Milton C , Tonetto Mateus R , Caetano Rafael DS , Castro Paulo HDS , Soares Ana C
Published: December 2016

Introduction

This study aimed to evaluate the occurrence of radiodermatitis in patients undergoing radiotherapy in the head and neck.

Materials and methods

Thirty-eight patients were evaluated 6 months after the end of radiotherapy to treat cancer in the head and neck region. The radiodermatitis was clinically classified as absent, acute, or chronic. Data, such as age, sex, race/ color, drinking and smoking habits, number of radiotherapy sessions, and conduction of adjuvant chemotherapy were also obtained. Fisher's exact test and Pearson's test were used to analyze the correlation of the independent variables and the presence of radiodermatitis.

Results

The mean age of the patients was 59.71 (± 10.67), and 29 (76.3%) were men, 24 (63.2%) were non-white race/ color, 28 (63.7%) were alcohol consumers, and 33 (86.8%) were smokers. The average number of radiotherapy sessions was 37.26 (± 7.66); 30 (78.9%) patients underwent chemotherapy; and 26 (68.4%) had chronic radiodermatitis. The only variable statistically related to the occurrence of radiodermatitis in the patients was smoking.

Conclusion

Radiodermatite was quite prevalent among the studied patients and was directly related to the smoking habit.

How to cite this article

Caetano RDS, Volpato LER, Castro PHDS, Borba AM, Aranha AMF, Kuga MC, Tonetto MR, Soares AC, Bandeca MC, Borges ÁH. Smoking influences the Occurrence of Radiodermatitis in Head and Neck-irradiated Patients. World J Dent 2017;8(1):55-58.
Manifestantes ou criminosos? A legitimação discursiva da tática Black Bloc como organização criminosa no jornalismo de revista
Authors: Gindri Eduarda Toscani , Budó Marília Denardin , Loureiro Caroline , Leão Ivanderson Pedroso
Published: December 2016

O presente artigo centra-se no tema da atribuição do status de criminoso aos movimentos e mobilizações sociais, por parte dos meios de comunicação de massa, focando no enquadramento da tática Black Bloc como tipo penal de “organização criminosa”. O trabalho investiga quais são as estratégias discursivas utilizadas pelos meio de comunicação que legitimam a atribuição aos manifestantes adeptos da tática do status de criminoso como integrantes de organizações criminosas. Para isso, partiu-se de uma revisão bibliográfica sobre os conceitos envolvidos, para então analisar os discursos das revistas, impressas e digitais, Veja, Época e Carta Capital sobre o tema. Concluiu-se que há agendamento da tática Black Bloc enquadrada como organização criminosa, porém, os meios de comunicação analisados confundem os tipos penais associativos. Além disso, há a omissão de que o tipo de organização criminosa tem origem para o combate ao crime organizado, preponderantemente em atividades de ordem econômica. Também se constatou que, apesar de ser uma categoria frustrada no âmbito jurídico, a organização criminosa é um tipo penal funcional para a política e para a construção de sentidos sobre criminalidade, reiterando o estereótipo do criminoso.
A Hipótese Colonial, um diálogo com Michel Foucault: a Modernidade e o Atlântico Negro no centro do debate sobre Racismo e Sistema Penal
Authors: Argolo Pedro , Piza Duarte Evandro , Queiroz Marcos Vinicius Lustosa
Published: December 2016

O presente texto, ao refletir sobre os limites das narrativas tradicionais e críticas sobre a história do controle social e de seus saberes, debate uma questão: de que modo o controle social numa determinada época estaria vinculado à raça e, especificamente, como ele produziria uma discriminação dos “negros”?Para responder a essa questão se propõe um diálogo com os conceitos de “vida nua” de Giorgio Agamben e o de “dispositivo” de Michel Foucault, revisitando as ideias da “hipótese colonial” na explicação da violência das formas de controle social, especialmente na constituição do racismo.A construção da análise sobre a raça, a partir do conceito de “dispositivo”, lança uma alternativa à oposição entre as noções de racismo como prática e como episteme. Ao mesmo tempo dá-se visibilidade na construção do biopoder às práticas e disputas em outras margens da Modernidade. A violência da Conquista passa a ser vista como práxis constitutiva, muito antes do surgimento do signo “raça”. No mesmo passo, a disputa no Atlântico Negro, pelo controle das Cidades Negras e das ressignificações políticas e culturais da Diáspora Africana, adquirem uma dimensão estratégica para refletir sobre o surgimento das práticas penais.
Write Like a Visual Artist: Tracing artists’ work in Canada’s textually mediated art world
Authors: Klostermann Janna
Published: December 2016

This study examines the social organisation of Canada’s art world from the standpoint of practising visual artists. Bringing together theories of literacy and institutional ethnography, the article investigates the literacy practices of visual artists, making visible how artists use written texts to participate in public galleries and in the social and institutional relations of the art world. Drawing on extended ethnographic research, including interviews, observational field notes and textual analyses, this study sheds light on the ways visual artists enact particular texts, enact organisational processes, and to enact the social and conceptual worlds they are a part of. Through the lens of visual artists, this study locates two particular texts – the artist statement and the bio statement – in the extended social and institutional relations of the art world.
Beyond Economic Interests: Critical Perspectives on Adult Literacy and Numeracy in a Globalised World
Authors: Atkinson Tannis , Jackson Nancy S
Published: December 2016

This volume reflects the many faces of the adult literacy and numeracy (ALN) field since the introduction, more than two decades ago, of OECD surveys that define and measure ALN as a contribution to economic productivity, efficiency and growth. The book highlights the transition to statistical tools as the only legitimate form of knowledge about literacy and explores a range of alternative visions and creative practices that focus on ‘the meaning of literacy and numeracy in people's lives’ (Yasukawa and Black 2016: 21).
Satellite altimetry reveals spatial patterns of variations in the Baltic Sea wave climate
Authors: Kudryavtseva Nadezhda , Soomere Tarmo
Published: December 2016

Abstract. The main properties of the climate of waves in the seasonally ice-covered Baltic Sea and its decadal changes since 1990 are estimated from satellite altimetry data. The data set of significant wave heights (SWH) from all existing ten satellites is cleaned and cross-validated against in situ buoy and echosounder measurements. Even though several satellite pairs (ENVISAT/JASON-1, SARAL/JASON-2, ERS-1/TOPEX) exhibit substantial mutual temporal drift, and calm situations are ignored, the overall picture is consistent. The annual mean SWH shows tentative increase 0.005 m/yr but higher quantiles behave in a cyclic manner with a timescale of 10–15 yr. Changes in the basin-wide average SWH have a strong meridional pattern: an increase in the central and western parts of the sea and decrease in the eastern part. This pattern is likely caused by a rotation of wind directions rather than by an increase in the wind speed.