bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Filling Predictions and Mechanical Mold Simulations for Composite Manufacturing Techniques: RTM Tool Development
Authors: Grössing Harald , Konstantopoulos Spiridon , Schledjewski Ralf
Published: July 2015

This paper presents the development of a novel omega-shaped resin transfer molding (RTM) tool, which is especially designed to host different types of sensors and to avoid common problems of RTM (e.g. uneven heating, low tool durability, deflection). Permeability measurements were executed in order to get real permeability measurements for numerical mold filling simulations. Three different kinds of flow behaviors (isotropic, orthotropic and anisotropic) were considered as filling patterns and the flow front predictions. Due to the U-shaped composite part design, the mold curvature effects on the flow front propagation caused by the increased fiber volume content in these areas were also taken into account. The tool was designed with a heating ability using purified liquid water guided to a channel circuit within both top and bottom halves of the tool. Deflection and heat transfer simulations were performed with the finite element method (FEM). All three executed simulations (filling, heat transfer and deflection) were used as a guideline for the final mold design.
To the Question on the Friction Assessment Methods Applied for Metal Forming Operations
Authors: Petrov Michael A. , Petrov Pavel A. , Yafaev Ramil R.
Published: July 2015

In many technological processes, friction results strong wear of the tool set and causes defect forgings. Many experimental investigations started in XX century had shown, that there are some laboratory methods with trustable results, which can be applied for friction prediction in real processes of metal forming. Among them such tests like ring compression test, direct and backward extrusion test, double cup extrusion test and T-shape compression test can be selected. Each of them has limitations that do not allow distributing the results of one certain test on all metal forming processes. Moreover, the tests should be done in a proper way to guarantee the adequate results that could be time-consuming. With the help of FE-analysis, the authors investigated numerically the intensity of the pressure distribution on the tool's surfaces and coupled the results with the real situations, observed in the metal forming operations. For the relative young T-shape compression technique oriented on the high contact pressure values authors have examined the changing of the relative deformed material volume as the merit of the friction characterisation.
Implementation of a Constitutive Model for the Mechanical Behavior of TWIP Steels and Validation Simulations
Authors: Erhart Andrea , Haufe André , Butz Alexander , Zapara Maksim , Helm Dirk
Published: July 2015

High manganese content TWinning Induced Plasticity (TWIP) steels are promising for the production of lightweight components due to their high strength combined with extreme ductility, see [1]. This paper deals with the implementation of a constitutive model for the macroscopic deformation behavior of TWIP steels under mechanical loading with the aim of simulating metal forming processes and representing the behavior of TWIP-steel components – for example under crash loading - with the Finite Element code LS-DYNA® and refers to our recently published papers: [2],[4],[5]. Within the present paper we focus on the implementation of the model formulated in [2] and its extension to stress dependent twinning effects.
Measurement and Analysis of the Differential Hardening of Ultralow Carbon Steel Sheets
Authors: Sekiguchi Chiharu , Saito Masazumi , Kuwabara Toshihiko
Published: July 2015

Multiaxial tube expansion tests were performed to precisely measure the work hardening behavior of mild steel sheets with different r-values for a range of strain from initial yield to fracture. The testing machine is capable of applying an arbitrary linear stress path to a tubular specimen using an electrical, closed-loop servo-control system for the axial force and internal pressure applied to the tubular specimen. Tubular specimens with an inner diameter of 44.6 mm were fabricated from the as-received sheet sample by roller bending and laser welding. Nine linear stress paths, σx(rolling direction) :σy (transverse direction) =1:0, 4:1, 2:1, 4:3, 1:1, 3:4, 1:2, 1:4, and 0:1, in the first quadrant of the principal stress space were applied to the tubular specimens to measure the contours of plastic work and the directions of the plastic strain rates. It was found that the shapes of the measured work contours changed with increasing plastic work, or equivalently with increasing the reference plastic strain ; the test materials exhibited differential hardening (DH). The general trend of the DH appeared to be affected by the average r-value, or equivalently by the texture, of the materials.
Assessment of Damage and Anisotropic Plasticity Models to Predict Ti-6Al-4V Behavior
Authors: Guzmán Carlos Felipe , Tuninetti Víctor , Gilles Gaëtan , Habraken Anne Marie
Published: July 2015

The plastic behavior of the Ti-6Al-4V alloy includes several features as strength differential effect, anisotropy and yield strength sensitivity to temperature and strain rate. Monotonic tensions in the three orthogonal directions of the material are performed to identify the Hill '48 yield criterion. Monotonic compression and plane strain tensile tests are also included in the experimental campaign to identify the orthotropic yield criterion of CPB06. An assessment of the two models is done by comparing the yield loci and the experimental data points for different levels of plastic work. A first approach of the damage modelling of the Ti-6AL-4V alloy is investigated with an extended Gurson-Tvergaard-Needleman damage model based on Hill '48 yield criterion. Finite element simulations of the experiments are performed and numerical results allows checking force-displacement curves until rupture and local information like displacement and strain fields. The prediction ability of the Hill '48, CPB and extended Gurson models are assessed on simple shear and notched tensile tests until fracture.
Rheological Model of Materials with Defects Containing Hydrogen
Authors: Belyaev Alexander , Polyanskiy Vladimir , Yakovlev Yuriy A.
Published: July 2015

A two-continua model is constructed which allows one to describe the kinetics of hydrogen in metals. The developed rheological model is appropriate for estimation of the hydrogen transition from mobile to bonded state depending on the stress-state relation and description of the localization of the connected hydrogen that results in the material fracture.
The Effect of Severe Plastic Deformation Processing on Creep Properties of Metallic Materials
Authors: Dvořák Jiří , Král Petr , Sklenička Vaclav , Svoboda Milan , Kvapilová Marie
Published: July 2015

Processing by severe plastic deformation (SPD) may be defined as such metals forming procedure in which a very high strain is imposed on a bulk material. This paper investigates the effect of different equal channel angular pressing (ECAP) routes and number of ECAP passes on resulting microstructure, mechanical properties and creep behaviour of selected materials. The distinction between various ECAP routes (A, B and C) and the difference in number of ECAP passes applied may lead to variations both in the macroscopic distortions of the individual grains and in the capability to develop a reasonably homogeneous and equiaxed ultrafine-grained microstructure. Experimental materials were processed by ECAP at room temperature using a die with an internal angle of 90° between the two parts of the channel. The ECAP pressing was performed by different routes up to 12 ECAP passes. Tensile creep tests were conducted at temperatures 473 - 673 K and at different applied stresses on ECAP materials and, for comparison purposes, on their unpressed states. Microstructure of samples was characterized by scanning electron microscope (SEM) equipped with the electron backscatter diffraction (EBSD) unit. In conclusion, the ECAP processing route and number of applied ECAP passes could play an important role in creep behaviour and their effect may be different for particular materials. The highest differences in processing routes were revealed for materials especially at lower number of ECAP passes. However, a little apparent dependence of the creep properties was observed during subsequent pressing.
Numerical and Experimental Investigation of a Modified Twin Roll Strip Casting Process for the Production of Clad Steel Strips
Authors: Vidoni Michele , Daamen Markus , Hirt Gerhard
Published: July 2015

A process for the production of clad steel strips by means of vertical twin-roll strip casting is under investigation at the Institute of Metal Forming (IBF). This production concept is based on the introduction of a solid strip in the casting pool in order to join it with the solidifying melt. The advantages of this concept are a shorter process chain and a higher energy efficiency compared to the existing cladding methods. The contact time and the thickness ratio between solid strip and solidifying melt, their relative position and the alloy combination are fundamental parameters to be considered in the design of this cladding process. A numerical model is used to predict the temperature increase in the solid strip and the solidification of the melt for the material combinations 1.4301/C75 and C75/Cu, and for two process configurations. Carbon steel and copper strips were introduced in the melting pool during casting experiments. Both carbon steel and copper strips could be clad without melting when positioned on the casting roll surface. This indicates that the surface temperature of the copper strip did not rise over 1084°C. Both the copper and the carbon steel strips show partial melting when introduced in a central position.
CNT and Graphene Filled Shape Memory Foams by Solid State Foaming
Authors: Santo Loredana , Tedde Giovanni Matteo , Quadrini Fabrizio , Mutlay Ibrahim
Published: July 2015

Epoxy-based shape memory (SM) foams have been produced by solid state foaming. According to this foaming technology, precursors are made by cold compaction of thermosetting powders. Subsequently, precursors foam by heating in an oven. In this study, the SM epoxy powder was mixed with multi-walled carbon nanotubes (MWCNTs) and graphene so as to produce SM composite foams. Two different filling contents were used (0.5 and 1 wt%). In order to study the effect of nano-fillers on SM properties of the epoxy foams, foam compressibility was measured at a temperature higher than the transition temperature of the SM epoxy foam (i.e. the glass transition temperature). Moreover, recovery load was measured after a 50% of memorized strain. Results show the positive effect of the fillers in functional and structural terms.
Process Design in Pulse Electrochemical Machining Based on Material Specific Data – 1.4301 and Electrolytic Copper as an Example
Authors: Steuer Philipp , Rebschläger Andreas , Ernst Alexander , Bähre Dirk
Published: July 2015

The Pulse Electrochemical Machining Process is an innovative, non-conventional process, based on the Electrochemical Machining process. Herein, pulsed current instead of constant current and a feed overlaid mechanical vibration of the tool electrode allows a higher precision and copying accuracy in contrast to the well-established ECM process. Yet, in this context the pulse-pause time and the length of the pulse on-time used in the process cause changes in the material removal while processing and therefore influences the processing result as well as cycle times and other industry relevant criteria. Understanding these pulse- and process specific changes is a key to the process design for industrial applications, since different sets and variations in parameters also change the final form and surface topography. This contribution shows, at the example of two materials 1.4301 and electrolytic copper, how a machining process can be designed and calculated based on material specific data. The way to acquire the necessary material data sets using industrial equipment, as well as the use and information which can be drawn from the data will be addressed.
Work-Hardening Behavior of Cold Rolled Interstitial-Free Steel Sheet and Dual Phase High Strength Steel Sheets Subjected to Two-Stage, Coaxial and Non-Coaxial Tension/Compression
Authors: Shirakami Satoshi , Yonemura Shigeru , Yoshida Tohru , Suzuki Noriyuki , Kuwabara Toshihiko
Published: July 2015

In-plane tension/compression tests of a cold rolled interstitial-free (IF) steel and sheet a 980MPa dual phase high strength steel sheet (980DP) were carried out to investigate the work-hardening behavior under two-stage loading paths. The two-stage loading paths consist of the uniaxial tension/compression for the rolling direction (RD) followed by unloading and subsequent uniaxial tension/compression in the 0°, 45° and 90° directions from the first loading direction (0°-, 45°- and 90°-loading). The work hardening behavior in the second loading was different between the 980DP and the IF steel. It was found that the work hardening behaviors were significantly affected by the inner product of the strain rate mode tensors for the first and second loading and that the effect of the deformation mode (tension/compression) was small.
Influence of Copolymer Architecture on Generation of Defects in Reactive Multilayer Coextrusion
Authors: Bondon Arnaud , Lamnawar Khalid , Maazouz Abderrahim
Published: July 2015

Several polymers can be combined in one multilayer structure by reactive coextrusion. Tie-layers are often used to compatibilize adjacent layers and may reduce or suppress interfacial instabilities and defects in multilayer coextrusion flow. However, a new additional defect defined as “grainy” defect can be observed. In our best of knowledge, no study in literature has been dedicated to understand its origin. The phenomena are quite complex due to the coupling of the effects of flow and the physico-chemical mechanisms at the interface. The aim of this work is to understand the relationship between the instabilities and defects encountered in multilayer coextruded films and the role of the copolymer formed in-situ between tie and barrier layers. Polyamide 6 (PA6) and ethylene-vinyl alcohol copolymer (EVOH) were used as barrier layers sandwiched in polypropylene (PP) with or without tie-layer based on polypropylene grafted maleic anhydride (PP-g-MA). Influence of process parameters and nature of the polymer pair on the generation of “grainy” defect has been assessed and related to the rheological and the physico-chemical properties of layers. These experiments showed that this defect appeared mainly in the compatibilized EVOH system and could be distinguished from the usual coextrusion instabilities. Interfacial properties between tie and barrier layers have been investigated. Shear stress relaxation experiments have been carried out on reactive tie/barrier bilayers. Due to the interphase generated in-situ, the relaxation behavior was altered by extending the relaxation time. Investigation of interfacial morphology highlighted that the copolymer architecture significantly affected the interface/interphase development and interface roughness. Hence, relationships between relaxation process, interfacial morphology and copolymer structure were correlated with the generation of grainy defects in coextrusion.
Foam Injection Moulding of PE/EVA Blends with an Azodicarbonamide Agent
Authors: SPINA Roberto
Published: July 2015

The main purposes of this work are the technical investigation of polymer melt interactions of a well-designed PE/EVA blend with an azodicarbonamide foaming agent and the evaluation of the final characteristics of the foamed products. The investigation is mainly focused on the material characterization of the PE/EVA blend with Differential Scanning Calorimetry, taking samples from the virgin materials and from the injection moulded parts.
Determining Volumetric Strain in Biaxial Deformation of PET at Temperatures and Strain Rates for Stretch Blow Moulding
Authors: Nixon James , MENARY Gary
Published: July 2015

For materials formed in the rubbery region eg. PET in the stretch blow moulding process, the normal assumption is that the material is incompressible. In this paper the validity of this assumption is challenged by conducting a series of experiments that measure the volumetric strain under different strain and temperature histories. Experiments have been conducted on a biaxial testing machine instrumented with lasers for measuring the strain through the thickness in combination with and digital image correlation for measuring the in plane strain for PET stretched in uniaxial and biaxial deformation between 90°C and 100°C. Results will be presented that show that the Poisson’s ratio for PET can vary between 0.4 and 0.55 depending on the test conditions. It is concluded that the values measured greater than 0.5 are due to the strain induced crystallinity that occurs with PET during the biaxial deformation process.______________________________________________________________________
Development of a Global Indicator to Assess Mechanical Tests
Authors: Souto Nelson , Thuillier Sandrine , Andrade-Campos António
Published: July 2015

Full-field measurement methods have emerged in the last years and these methods are characterized by directly providing displacement and strain fields for all points over the specimen surface. Thus, the design of heterogeneous tests can be performed for material parameter identification purposes since the inhomogeneous strain fields can be measured. However, (i) no defined criterion yet exists for designing new heterogeneous tests, (ii) it is rather difficult to compare and rate different tests and (iii) a quantitative way to define the best test for material behavior characterization of sheet metals has yet to be proposed. Due to this, the goal of this work is the development of a global indicator able to assess mechanical tests. The proposed indicator quantifies the strain state range, the deformation heterogeneity and the strain level achieved in the test, based on a continuous evaluation of the strain field up to rupture. This global indicator was applied to rank some classical tests, such as uniaxial tensile, simple shear, plane strain and biaxial tensile tests. These tests were carried out numerically by reproducing the virtual behavior of DC04 mild steel. A constitutive model composed by the non-quadratic Yld2004-18p yield criterion combined with a mixed isotropic-kinematic hardening law and a macroscopic rupture criterion was used. The performance of the tests was compared with the indicator and a ranking was established. The results obtained show that biaxial tension is the test providing more information for the mechanical behavior characterization of the material. It was also verified that plane strain test presents a better performance than simple shear and uniaxial tensile tests.
Computational Analysis of the Interaction between Impregnation, Forming and Curing in Pultrusion
Authors: Carlone Pierpaolo , Baran Ismet , Akkerman Remko , Palazzo Gaetano S.
Published: July 2015

Numerical and analytical models dealing with different physics involved in pultrusion are combined in the optic of an integrated analysis of the process. The impregnation stage is simulated by means of a CFD multiphase model, evaluating the pressure and velocity field in the liquid resin. Composite temperature and degree of cure are inferred using 3D thermo-chemical models. Finally, contact conditions, stresses and strains are derived applying computational simulation and analytical models, in order to predict the final pulling force. Different product sizes are considered, simulating suitable processing condition.
Mechanical and Tribological Characterization of Composite Laminates Manufactured by Liquid Composite Molding Processes
Authors: Merola Massimiliano , Carlone Pierpaolo , Ruggiero Alessandro , Archodoulaki Vasiliki Maria
Published: July 2015

The aim of the present work is to investigate the influence of the Vacuum Assisted Resin Transfer Molding process steps on the impregnation quality of the laminates as well as on mechanical and tribological properties of the processed material. Composite laminates were realized using epoxy resin reinforced with carbon (CF) or glass continuous (GF) fibers. Two different textile architectures, namely non-crimp fabrics (UD) and woven-mat (0/90), were used and various processing conditions were employed. Optical observations revealed an unexpected trend relatively to the intra and inter bundle voids concentration with respect to the impregnation velocity, especially using UD-CF and UD-GF reinforcements and low impregnation rate. Tensile and three points bending tests highlighted the strong impact of fiber material and architecture on mechanical properties, whereas the presence of voids played a slightly influence on the fiber dominated characteristics analyzed. Tribological outcomes evidenced a reduction of the friction coefficient when the resin is reinforced by carbon or glass fibers as well as when the sliding direction of the counterbody is oriented parallel to the fiber direction.
Determination of the Plastic Strain by Spherical Indentation of Uniaxially Deformed Sheet Metals
Authors: Idriss Mohamad , Bartier Olivier , Mauvoisin Gérard , Moussa Charbel , Gazo Hanna Eddie , Hernot Xavier
Published: July 2015

This work consists of determining the plastic strain value undergone by a material during a forming process using the instrumented indentation technique (IIT). A deep drawing steel DC01 is characterized using tensile, shear and indentation tests. The plastic strain value undergone by this steel during uniaxial tensile tests is determined by indentation. The results show that, the identification from IIT doesn’t lead to an accurate value of the plastic strain if the assumption that the hardening law follows Hollomon law is used. By using a F.E. method, it is shown that using a Voce hardening law improves significantly the identification of the hardening law of a pre-deformed material. Using this type of hardening law coupled to a methodology based on the IIT leads to an accurate determination of the hardening law of a pre-deformed material. Consequently, this will allow determining the plastic strain value and the springback elastic strain value of a material after a mechanical forming operation.
Finite Element Modeling of Deformation Behavior of Steel Specimens under Various Loading Scenarios
Authors: Banerjee Dilip , Iadicola Mark , Creuziger Adam , Foecke Tim
Published: July 2015

Lightweighting materials (e.g., advanced high strength steels, aluminum alloys etc.) are increasingly being used by automotive companies as sheet metal components. However, accurate material models are needed for wider adoption. These constitutive material data are often developed by applying biaxial strain paths with cross-shaped (cruciform) specimens. Optimizing the design of specimens is a major goal in which finite element (FE) analysis can play a major role. However, verification of FE models is necessary. Calibrating models against uniaxial tensile tests is a logical first step. In the present study, reliable stress-strain data up to failure are developed by using digital image correlation (DIC) technique for strain measurement and X-ray techniques and/or force data for stress measurement. Such data are used to model the deformation behavior in uniaxial and biaxial tensile specimens. Model predictions of strains and displacements are compared with experimental data. The role of imperfections on necking behavior in FE modeling results of uniaxial tests is discussed. Computed results of deformation, strain profile, and von Mises plastic strain agree with measured values along critical paths in the cruciform specimens. Such a calibrated FE model can be used to obtain an optimum cruciform specimen design.
Climb Enabled Discrete Dislocation Plasticity of Superalloys
Authors: Ayas Can , Deshpande Vikram
Published: July 2015

Ni-based superalloys comprising of elastic particles embedded in a single crystal elastic-plastic matrix are usually subject to loading at elevated service temperatures. In order to enhance the understanding of high temperature deformation mechanisms a two dimensional discrete dislocation plasticity framework wherein the dislocations movement that incorporates both glide and climb is formulated. The climbing dislocations are modelled as point sources/sinks of vacancies and the vacancy diffusion boundary value problem is solved by superposition of the vacancy concentration fields of the point sources/sinks in an infinite medium and a complementary non-singular solution that enforces the relevant boundary conditions. The vacancy concentration field along with the Peach-Kohler force provides the climb rate of the dislocations.
Perceptions of newly-qualified nurses performing compulsory community service in KwaZulu-Natal
Authors: Govender Selverani , Brysiewicz Petra , Bhengu Busisiwe
Published: July 2015

Background: Compulsory community service (CCS) for nurses commenced in South Africain January 2008 after it was legislated in the new Nursing Act (Act No. 33 of 2005). Nurses completing their registered nurse programme are registered as community nurse practitioners (CNPs) during the CCS period and make up the largest number of health professionals serving CCS. Whilst health institutions have welcomed CNPs as additional resources for the shortage of nursing staff, no structured guidelines have been provided at a regional level as to how these nurses should be utilised or managed during the CCS year. To date, no large-scale study has been conducted on nurses carrying out CCS in order to generalise the findings.Objectives: To establish the perceptions of newly-qualified nurses carrying out CCS in KwaZulu-Natal, South Africa.Method: A quantitative survey design was used to obtain data from a randomly selected sample of the 2012 cohort of nurses carrying out CCS in KwaZulu-Natal.Results: CNPs have a positive attitude toward CCS and perceive themselves as being well prepared for the year of community service in terms of knowledge, skills and ability to administer nursing care. They identified positive benefits of the year of community service.The concerns raised were limited orientation and support; and a few CNPs experienced problems of acceptance by the nurses with whom they work.Conclusion: It is recommended that all health institutions who receive CNPs develop structured orientation and support for these nurses in order to promote their development, thereby enhancing their benefit to the communities they serve.
Martin Luther oor oneerlikheid in die ekonomie
Authors: Van Wyk I.W.C.
Published: July 2015

Martin Luther about dishonesty in the economy. This article is about Martin Luther’s economic ethics. Background information is given about the economic situation 500 years ago. The high levels of poverty in Germany were the main reason behind the health crisis experienced at that time. Luther reprimanded the heads of families to work diligently and honestly in order to ensure a stable income for the family. He prophetically also criticised the dishonesty on the market place. He exposed the many attempts by people to exploit the poor. An overview is given of the development of his economic thought. The focus falls, however, on his essay Von Kaufshandlung und Wucher (1524) [On trade and profiteering].
Developing Emotional Intelligence as a key psychological resource reservoir for sustained student success
Authors: Görgens-Ekermans Gina , Delport Marthinus , Du Preez Ronel
Published: July 2015

Orientation: The dire educational situation in South Africa has urged researchers to investigate predictors of sustained student success. Research purpose: To investigate to what extent an Emotional Intelligence (EI) intervention impacts the level of EI, and critical psychological resources (affect balance, cognitive thoughtpattern strategies as a sub-component of self-leadership, perceived stress and academic selfefficacy) necessary for student success.Motivation for the study: Non-cognitive personal resources (such as EI) may indirectly contribute to student success. Research design, approach and method: A controlled experimental research design was conducted to test the effect of an EI developmental intervention on affect balance, academic self-efficacy, cognitive thought-pattern strategies, and perceived stress, using a sample of first-year students (n = 114). Main findings: Limited support of the utility of the intervention to increase EI emerged; whilst stronger support emerged that academic self-efficacy was affected by the intervention. No direct empirical support for the impact of increased EI on the other measured psychological resources was obtained, although some trends in the data could be observed. Practical/managerial implications: Investments in EI developmental interventions, as part of student-support initiatives, should be further investigated to sufficiently justify its potential to influence sustained student success.Contribution/value-add: The results of this study lay a foundation that suggest EI could be malleable and influence academic self-efficacy. More research is necessary regarding supplementary teaching and learning initiatives focused on non-cognitive personal resources, which are complementary to the academic offering at tertiary institutions, with the expectation of increasing the student success rates.
Effects of dexmedetomidine and clonidine as propofol adjuvants on intra-operative hemodynamics and recovery profiles in patients undergoing laparoscopic cholecystectomy: A prospective randomized comparative study
Authors: Anjum Naz , Tabish Hussain , Debdas Saha , Bani Hembrom P , Rajat Choudhuri , Anjana Basu Ghosh Dastidar
Published: July 2015

Context: Alpha-2 (α2) adrenergic receptor agonists, clonidine and dexmedetomidine, are widely used as adjuvants during anesthesia for analgesic, sedative, sympatholytic, and cardiovascular stabilizing effects. Aims: We compared effects of clonidine and dexmedetomidine (as propofol adjuvants) on intra-operative hemodynamics, recovery time, and postoperative cognitive function impairment. Subjects and Methods: Forty-five American Society of Anesthesiologists I and II patients, scheduled for laparoscopic cholecystectomy were divided into three groups (n = 15). Group C patients received bolus of clonidine 3 μg/kg followed by a continuous infusion; Group D patients received dexemedetomidine 1 μg/kg and a continuous infusion; and Group P patients received a bolus of normal saline followed by an infusion. Intra-operative mean arterial pressure (MAP) and pulse rate (PR) were measured throughout the surgery. Bispectral index was maintained at 55 ΁ 5 by titrating propofol infusion rate. The time between the interruption of anesthesia and eye opening (recovery time) was measured. Cognitive function was assessed using short mental status questionnaire at 15, 30, 45, and 60 min postoperatively. Results: The sympathetic response to laryngoscopy and extubation on MAP and PR were significantly reduced with the use of clonidine and dexmedetomidine (P < 0.05). The recovery was delayed (P < 0.05) with both the drug combinations and it was more pronounced with dexmedetomidine (P < 0.05). Dexmedetomidine group showed cognitive impairment in a postoperative period lasting up to an hour. Conclusions: When co-administered with propofol, both clonidine, and dexmedetomidine attenuate sympathetic response to laryngoscopy and extubation but cause delay in the recovery from anesthesia. Dexmedetomidine causes impairment of postoperative cognitive functions.
Visceral adipose tissue influences on coronary artery calcification at young and middle-age groups using computed tomography angiography
Authors: Abazid Rami M , Kattea M Obadah , Sayed Sawsan , Saqqah Hanaa , Qintar Mohammed , Smettei Osama A
Published: July 2015

Purpose: The purpose of the study was to evaluate the impact of excessive visceral adipose tissue (VAT) on subclinical coronary atherosclerosis and coronary artery calcifications (CAC) in young and middle-age groups using multislice computed tomography. Methods: This study is a single center, cross-sectional study. Eligible patients (n = 159), who under the age of 61 years, with chest pain and mild to moderate probability to have coronary artery disease (CAD) were enrolled. Coronary calcium score and epicardial adipose tissue (EAT) were measured at the level of the left main coronary artery while VAT was measured at the level of the iliac crest. Results: The average age was (48 ± 8 years). The mean VAT was (38 ± 21 cm 2 ) with no significant difference between men and women (38 ± 22 vs. 37 ± 19 P = 0.8) respectively. Student′s t-test analysis showed significantly higher VAT in patients with detectable CAC than patients with no CAC (48 ± 24 vs. 33 ± 18 P = 0.00002), respectively. Univariate regression analysis showed that VAT and EAT, are strong predictor for CAC (hazard ratio [HR] 1.034, 95% confidence interval [CI: 1.016-1.052]. P <0.001 and [HR] 1.344, 95% CI: [1.129-1.601] P = 0.001), respectively. Conclusion: Excessive VAT is significantly associated with positive CAC. VAT can strongly predict subclinical CAD in individuals at young and middle-age groups.
Interleukin 1β—A Potential Salivary Biomarker for Cancer Progression?
Authors: Idris Adi , Ghazali Nur B. , Koh David
Published: July 2015

The relationship between cancer and inflammation is a complex but intimate one. Decades of work has shown to us that cancer progression is influenced by a multitude of factors, including genetic, environmental, and immunological factors. We often overlook that cancer progression is also a pathological consequence of a dysregulated inflammatory control in the body. A current emerging topic in cancer research is the role of inflammasomes in carcinogenesis. The inflammasome is a multicomplex protein platform that when activated results in the release of proinflammatory cytokines, such as interleukin (IL)-1β. There is increasing evidence suggesting that IL-1β plays a pivotal role in cancer progression. This short review proposes the possibility of using IL-1β as a potential cancer progression biomarker and discusses the use of saliva as a model biological fluid for measuring physiological IL-1β levels in the body.
Infiltrative Cardiomyopathies
Authors: Bejar David , Colombo Paolo C. , Latif Farhana , Yuzefpolskaya Melana
Published: July 2015

Infiltrative cardiomyopathies can result from a wide spectrum of both inherited and acquired conditions with varying systemic manifestations. They portend an adverse prognosis, with only a few exceptions (ie, glycogen storage disease), where early diagnosis can result in potentially curative treatment. The extent of cardiac abnormalities varies based on the degree of infiltration and results in increased ventricular wall thickness, chamber dilatation, and disruption of the conduction system. These changes often lead to the development of heart failure, atrioventricular (AV) block, and ventricular arrhythmia. Because these diseases are relatively rare, a high degree of clinical suspicion is important for diagnosis. Electrocardiography and echocardiography are helpful, but advanced techniques including cardiac magnetic resonance (CMR) and nuclear imaging are increasingly preferred. Treatment is dependent on the etiology and extent of the disease and involves medications, device therapy, and, in some cases, organ transplantation. Cardiac amyloid is the archetype of the infiltrative cardiomyopathies and is discussed in great detail in this review.
The impact of a health IT changeover on Medical Imaging Department work processes and turnaround times
Authors: Georgiou A. , Lymer S. , Hordern A. , Ridley L. , Westbrook J. , Prgomet M.
Published: July 2015

Objectives: To assess the impact of introducing a new Picture Archiving and Communication System (PACS) and Radiology Information System (RIS) on: (i) Medical Imaging work processes; and (ii) turnaround times (TATs) for x-ray and CT scan orders initiated in the Emergency Department (ED).

Methods: We employed a mixed method study design comprising: (i) semi-structured interviews with Medical Imaging Department staff; and (ii) retrospectively extracted ED data before (March/ April 2010) and after (March/April 2011 and 2012) the introduction of a new PACS/RIS. TATs were calculated as: processing TAT (median time from image ordering to examination) and reporting TAT (median time from examination to final report).

Results: Reporting TAT for x-rays decreased significantly after introduction of the new PACS/RIS; from a median of 76 hours to 38 hours per order (p<.0001) for patients discharged from the ED, and from 84 hours to 35 hours (p<.0001) for patients admitted to hospital. Medical Imaging staff reported that the changeover to the new PACS/RIS led to gains in efficiency, particularly regarding the accessibility of images and patient-related information. Nevertheless, assimilation of the new PACS/RIS with existing Departmental work processes was considered inadequate and in some instances unsafe. Issues highlighted related to the synchronization of work tasks (e.g., porter arrangements) and the material set up of the work place (e.g., the number and location of computers).

Conclusions: The introduction of new health IT can be a “double-edged sword” providing improved efficiency but at the same time introducing potential hazards affecting the effectiveness of the Medical Imaging Department.

Citation: Georgiou A, Prgomet M, Lymer S, Hordern A, Ridley4 L, Westbrook J.The impact of a health IT changeover on Medical Imaging Department work processes and turnaround times: a mixed method study. Appl Clin Inform 2015; 6: 443–453

http://dx.doi.org/10.4338/ACI-2015-01-RA-0014
The Influence of Relaxation Training on Respiratory Variability and Self-Reported Relaxation
Authors: Wuyts Ruth , Vlemincx Elke , Van Diest Ilse , Van den Bergh Omer
Published: July 2015

From a dynamic systems perspective, healthy breathing is characterized by complex variability. However, slow regular breathing instructions are often included in relaxation techniques. This study investigates the influence of relaxation training on natural breathing dynamics. Spontaneous breathing was measured in healthy persons during 5 sessions of relaxation training without breathing instructions (N = 29) vs. during quiet sitting resembling spontaneous relaxation (N = 29). Each session started with 10 minutes baseline recordings and ended with a mental stressor and a recovery phase. Results showed no differences between conditions in subjective relaxation and mean respiratory parameters. However, structured breath-to-breath variability increased across sessions during baseline and stress in the relaxation group only. In the control group, total variability increased across sessions during stress without concomitant changes in structured variability. The results point to the importance of respiratory variability in breathing regulation and suggest integration of a dynamic systems perspective in relaxation research.
Impact of future land cover changes on HNO3 and O3 surface dry deposition
Authors: Verbeke T. , Lathière J. , Szopa S. , de Noblet-Ducoudré N.
Published: July 2015

Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s−1) in VdO3 and a decrease of −0.06 cm s−1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and −15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario induces also an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the North Hemisphere during winter especially in Eurasia, by +50 % (+0.07 cm s−1) for VdO3 and +100 % (+0.9 cm s−1) for VdHNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be non-negligible and should be therefore considered in biosphere-atmospheric chemistry interaction studies in order to have a fully consistent picture.
New characteristics of submicron aerosols and factor analysis of combined organic and inorganic aerosol mass spectra during winter in Beijing
Authors: Zhang J. K. , Ji D. S. , Liu Z. R. , Hu B. , Wang L. L. , Huang X. J. , Wang Y. S.
Published: July 2015

Abstract. In recent years, an increasing amount of attention has been paid to heavy haze pollution in Beijing, China. In addition to Beijing's population of approximately 20 million and its 5 million vehicles, nearby cities and provinces are host to hundreds of heavily polluting industries. In this study, a comparison between observations in January 2013 and January 2014 showed that non-refractory PM1 (NR-PM1) pollution was weaker in January 2014, which was primarily caused by variations in meteorological conditions. For the first time, positive matrix factorization (PMF) was applied to the merged high-resolution mass spectra of organic and inorganic aerosols from aerosol mass spectrometer measurements in Beijing, and the sources and evolution of NR-PM1 in January 2014 were investigated. The two factors, NO3-OA1 and NO3-OA2, were primarily composed of ammonium nitrate, and each showed a different degree of oxidation and diurnal variation. The organic fraction of SO4-OA showed the highest degree of oxidation of all PMF factors. The hydrocarbon-like organic aerosol (OA) and cooking OA factors contained negligible amounts of inorganic species. The coal combustion OA factor contained a high contribution from chloride in its mass spectrum. The NR-PM1 composition showed significant variations in January 2014, in which the contribution of nitrate clearly increased during heavy pollution events. The most effective way to control fine particle pollution in Beijing is through joint prevention and control measures at the regional level, rather than a focus on an individual city, especially for severe haze events.
Impacts of Amazonia biomass burning aerosols assessed from short-range weather forecasts
Authors: Kolusu S. R. , Marsham J. H. , Mulcahy J. , Johnson B. , Dunning C. , Bush M. , Spracklen D. V.
Published: July 2015

Abstract. The direct radiative impacts of Biomass Burning Aerosols (BBA) on meteorology are investigated using short-range forecasts from the Met Office Unified Model (MetUM) over South America during the South American Biomass Burning Analysis (SAMBBA). The impacts are evaluated using a set of three simulations: (i) no aerosols, (ii) with monthly mean aerosol climatologies and (iii) with prognostic aerosols modelled using the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC) scheme. Comparison with observations show that the prognostic CLASSIC scheme provides the best representation of BBA. The impacts of BBA are quantified over central and southern Amazonia from the first and second day of two day forecasts during 14 September–03 October 2012. On average, during the first day of the forecast, including prognostic BBA reduces the clear-sky net radiation at the surface by 15 ± 1 W m−2, and reduces net TOA radiation by 8 ± 1 W m−2, with a direct atmospheric warming of 7 ± 1 W m−2. BBA-induced reductions in all-sky radiation are smaller in magnitude: 9.0 ± 1 W m−2 at the surface and 4.0 ± 1 W m−2 at TOA. In this modelling study the BBA therefore exert an overall cooling influence on the Earth–atmosphere system, although some levels of the atmosphere are directly warmed by the absorption of solar radiation. Due to the reduction of net radiative flux at the surface the mean 2 m air temperature is reduced by around 0.1 ± 0.02 °C. The BBA also cools the boundary layer (BL) but warms air above by around 0.2 °C due to the absorption of shortwave radiation. The overall impact is to reduce the BL depth by around 19 ± 8 m. These differences in heating lead to a more anticyclonic circulation at 700 hPa, with winds changing by around 0.6 m s−1. Inclusion of BBA in the MetUM significantly improves forecasts of temperature and relative humidity, but effects were small compared with model error and differences between effects from climatological and prognostic BBA were not significant. Locally, on a 150 km scale, changes in precipitation reach around 4 mm day−1 due to changes in the location of convection. Over Amazonia, including BBA in the simulation led to fewer rain events that were more intense. This change may be linked to the BBA changing the vertical profile of stability in the lower atmosphere. The localised changes in rainfall tend to average out to give a 5 % (0.06 mm day−1) decrease in total precipitation over the Amazonian region (except on day 2 with prognostic BBA). The change in water budget from BBA is, however, dominated by decreased evapotranspiration from the reduced net surface fluxes (0.2 to 0.3 mm day−1), since this term is larger than the corresponding changes in precipitation and water vapour convergence.