bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Use of an Internal Mixer For the Rheological Characterizattion of Maize Starch
Authors: Brouillet-Fourmann Stéphanie , Carrot Christian , Mignard Nathalie , Prochazka Frédéric
Published: May 2019

The rheological behaviour of hydrated maize starch is investigated by means of a Haake internal mixer equipped with a sealed chamber. Results were obtained at temperatures between 89 and 115°C with water content between 25 and 30%. Through a proper calibration torque measurements and rotation speeds are converted to shear stress and shear rate data and this leads to the plot of a flow curve in the 10 - 1000 s-1 range. The data are compared with results of capillary rheometer and show that the mixer enables a reproducible plastification of the maize starch. The viscosity of the maize starch in the high shear rate range can be described by an apparent power law taking into account the moisture and temperature effects. On a larger range of shear rate, a Carreau law is preferred but the dependence on the temperature can only be described with shift factors that require a moisture dependent activation energy. Finally, this later discrepancy can be avoided by using a reference temperature to fulfil the iso-free volume condition by taking a constant temperature difference towards the glass transition of the samples. The glass transition is calculated by the Couschman and Karasz equation.
Linear Viscoelastic Behavior of Bentonite-Water Suspensions
Authors: Bekkour Karim , Kherfellah Nadia
Published: May 2019

Bentonite are extensively used materials in a wide range of applications. Creep and oscillatory shear experiments in the linear viscoelastic domain were carried out on bentonite-water suspensions at different solid fractions. It was found that bentonite dispersions exhibit important viscoelastic behavior which could be represented by the generalized Kelvin-Voigt mechanical model. It is well known that an exhaustive study of colloidal dispersions may require the determination of its viscoelastic properties over a wide frequency scale. Unfortunately, due to microstructure changes, the experiments are limited in time. In order to avoid such limitation, oscillatory data were deduced from creep curves - without actually vibrating the clay dispersions - because a periodic experiment at frequency ω is qualitatively equivalent to a creep test at time 1/ω. That is, it was possible to complete the dynamic response in the low-frequency range using data obtained from the transient response in creep.
The Effect of Yellowing Inhibitor Total Charge on The Rheology of Paper Coating
Authors: El-Sadi Haifa , Esmail Nabil
Published: May 2019

New compounds, called inhibitors, provide anti-yellowing effect for mechanical pulps and papers, when added to the coating formulation. The rheology of coating mixtures, which contain clay, ground calcium carbonate, starch, latex, inhibitors and other minor additives, affects to a certain extent the final quality of the coated paper. The purpose of this work is to investigate the effect of the total weight charge of inhibitors, when present between coating color ingredients, on the thixotropy and visco-elasticity of the mixture and other rheological properties. We also study the degree of interaction between inhibitor and coating ingredients using Transmission Electron Microscope (TEM) and water retention measurements.

For the industrially preferred inhibitor system of low RS/UVA ratio and high total charge the coating formulation will have a significant increase in the general value of viscosity and a clear and profound shear-thinning behavior. Under the desired conditions of higher total charge the coating formulation acquires significant thixotropic behavior. A higher level of energy is required to coat such formulation. The elastic modulus increases with frequency. This rise in the elastic modulus reveals the increasing interaction between particles in the coating formulation. The total charge does not affect the resistance of a coating color to the applied stress. The coating color with low total charge has the strongest water holding capability decreasing with increasing total charge.
Apparent Viscosity and First Normal Stress of Starch Dispersions: Role of Continuous and Dispersed Phases, and Prediction with the Goddard-Miller Model
Authors: Genovese Diego B. , Rao M. A.
Published: May 2019

Apparent viscosity, ηa, and first normal stress coefficient, ψ1, of six different concentrations of cross-linked waxy maize (CWM), 3.5-5 % w/w, and tapioca, 2.8-4 % w/w, starch dispersions (SDs) showed power law relationships with shear rate, ̇γ , and increased with starch concentration. In both ηa and ψ1, volume fraction of the granules, ϕ, played a more important role than the amylose content of the continuous phase. Slope of ηa - ̇γ curves increased mildly with starch concentration, while slope of ψ1 - ̇γ curves was almost the same for CWM at all concentrations and 4 % tapioca SDs. Values of ηa and ψ1 predicted from dynamic rheological and apparent viscosity data based on the Goddard-Miller model were in reasonable agreement with experimental values.
Radiation Scattering by Dilute Polymer Solutions in Shear Flow: An Example of Mesoscale Modeling and Brownian Dynamics Simulation
Authors: Cifre J.G. Hernández , de la Torre J. García
Published: May 2019

The intention of the paper is to illustrate the ability of the Brownian dynamics simulation technique applied to mesoscale polymer models in order to reproduce light scattering experiments of dilute polymer solution under flow. After suitable parameterization of a real polymeric system, polystyrene solved in a oligostyrene/toluene mixture at 299 K (good solvent conditions), a bead-spring model of the polymer chain is built and used to generate molecular trajectories on a computer. Such trajectories will capture the deformational and orientational processes experienced by the real polymer chain under flow. Then, from the set of molecular conformations generated, several polymer properties as well as typical scattering patterns can be reproduced quite accurately. FENE springs were used and excluded volume and non-preaveraging hydrodynamic interaction were taken into account in order to build a chain model as realistic as needed.
Direct Simulation of Fluid Transport at Solid Interfaces with a Multiscale Lattice-Boltzmann Finite-Volume Method
Authors: Rotondi R. , Succi S. , Bella G.
Published: May 2019

It is shown that the combined use of a mesoscopic lattice Boltzmann solver with finite-volume techniques, both enriched with local-refinement (multiscale) capabilities, permits to describe transport phenomena at fluid-solid interfaces to a degree of detail which may help dispensing with empirical correlations.
Creeping Sphere-Plane Squeeze Flow to Determine the Zero-Shear-Rate viscosity of HDPE Melts
Authors: Cua Edwin C. , Shaw Montgomery T.
Published: May 2019

A creeping squeeze flow apparatus [1 - 2] was modified with a Fizeau interferometer optical motion transducer and equipped with a high-temperature, high-vacuum enclosure. Long-term squeeze flow experiments were done on a broad-MW, 1 melt-flow index commercial HDPE at 190˚C, with runs covering about a week. Over this period, no thermal degradation of the polymer was observed, and the geometry of the apparatus was stable. Low-shear-rate viscosities were measured within the maximum shear rates from 1.7 × 10−5 to 7.6 × 10−5 1/s (stress ~ 1.7 to 8 Pa), resulting in an two-decade expansion in the experimental window for this difficult-to-characterize HDPE resin with long relaxation times.
Phenomenological Modelling of Non-Monotonous Shear Viscosity Functions
Authors: David J. , Filip P.
Published: May 2019

The aim of this paper is to present a new phenomenological rheological model suitable for the description of a wide class of viscoelastic fluids. Classical phenomenological models predict the relation shear viscosity vs. shear rate (or shear stress) for shear-thinning (or thickening) materials exhibiting smooth monotonous passage from the first - upper (lower) - Newtonian plateau to the second - lower (upper) - one. However, present state of non-Newtonian materials used in practice (ranging from aqueous surfactant solutions, bituminous materials, associative polymers, polymer thickeners, lacquers and gels, to some special disperse systems, etc.) evokes the need to describe this - for many materials non-monotonous - relation in the corresponding way, i.e. through the sufficiently simple phenomenological model with a moderate number of parameters. A six-parameter model enabling description of not only monotonous but also non-monotonous course of shear viscosity function against shear rate (stress) is proposed including physical characterisation of the parameters. This model describes not only extreme points (maximum or minimum) but also a possible appearance of intermediate Newtonian plateau or its indication. The meaning and influence of the individual six parameters is documented on the experimental data published in the literature. There is a good agreement of the model proposed with many different experimental data representing different rheological behaviour. The applicability of this model for a wide class of viscoelastic materials is its principal advantage over the hitherto published phenomenological models.
Extensional Viscosity of Coating Colors and its Relation With Jet Coating Performance
Authors: Arzate A. , Ascanio G. , Carreau P.J. , Tanguy P.A.
Published: May 2019

An orifice flowmeter was used to measure the extensional viscosity of several non-pigmented fluids and paper coating colors containing calcium carbonate as pigment in the context of a jet coating application. The orifice flowmeter was first calibrated in terms of a dimensionless Euler number versus Reynolds number curve with Newtonian fluids. The calibration curve was then used to determine the apparent extensional viscosity of coating colors. In the strain rate range investigated, all the fluids were found to exhibit strain-thinning and the Trouton ratio of the coating colors was in the range 5 to 20. Jet coating tests were also carried out in order to evaluate the effect of the extensional viscosity on the jet performance. The extensional viscosity was shown to be a key parameter determining the configuration of the downstream meniscus in the web contact region.
Rheological Studies of Interferon Creams
Authors: Zumalacárregui Lourdes , Vázquez Miguel , Estévez Tania , Aguilera Ana , Hardy Eugenio
Published: May 2019

The determination of flow curves and the apparent viscosity curves at 28°C of creams containing human leukocyte alpha interferon as active principle is presented in this paper. These creams are used for the treatment of papiloma virus and herpes simplex. It is demonstrated that their behaviour corresponds to a thixotropic fluid. The Herschel-Bulkley model parameters are presented and discussed as an indicator of the grade of thixotropy. Apparent viscosity plotted as a function of shear rate and storage time allows defining the time period in which the samples recover their initial structure. Additionally it was concluded that for determining the quality of the product, the acceptance limit of the viscosity should be specified for a given shear rate.
Capillary Break-up Rheometry of Low-Viscosity Elastic Fluids
Authors: Rodd Lucy E. , Scott Timothy P. , Cooper-White Justin J. , McKinley Gareth H.
Published: May 2019

We investigate the dynamics of the capillary thinning and break-up process for low viscosity elastic fluids such as dilute polymer solutions. Standard measurements of the evolution of the midpoint diameter of the necking fluid filament are augmented by high speed digital video images of the break up dynamics. We show that the successful operation of a capillary thinning device is governed by three important time scales (which characterize the relative importance of inertial, viscous and elastic processes), and also by two important length scales (which specify the initial sample size and the total stretch imposed on the sample). By optimizing the ranges of these geometric parameters, we are able to measure characteristic time scales for tensile stress growth as small as 1 millisecond for a number of model dilute and semi-dilute solutions of polyethylene oxide (PEO) in water and glycerol. If the final aspect ratio of the sample is too small, or the total axial stretch is too great, measurements are limited, respectively, by inertial oscillations of the liquid bridge or by the development of the well-known beads-on-a-string morphology which disrupt the formation of a uniform necking filament. By considering the magnitudes of the natural time scales associated with viscous flow, elastic stress growth and inertial oscillations it is possible to construct an “operability diagram” characterizing successful operation of a capillary breakup extensional rheometer. For Newtonian fluids, viscosities greater than approximately 70 mPas are required; however for dilute solutions of high molecular weight polymer, the minimum viscosity is substantially lower due to the additional elastic stresses arising from molecular extension. For PEO of molecular weight 2 · 106 g/mol, it is possible to measure relaxation times of order 1 ms in dilute polymer solutions with zero-shear-rate viscosities on the order of 2 – 10 mPas.
Temperature Calibration of Rotational Rheometers with Electrically Heated Tools and Hood Oven
Authors: Schweizer Thomas
Published: May 2019

The calibration of the temperature control unit of a rotational rheometer with a hood oven is shown. The calibration technique shown for a Paar-Physica rheometer can be adapted to any rheometer with hood oven (indirect heating). The temperature of the bottom fixed plate and the air bearing suspended cone or plate are measured independently. By keeping the amount of venting gas constant, the set temperature of the hood oven is adjusted to reach a minimum gradient across the measuring gap. The calibration procedure is optimized to keep the oven as close as possible to the measuring position.
A Model for Velocity Profile in Turbulent Boundary Layer with Drag Reducing Surfactants
Authors: Krope A. , Krope J. , Lipus L.C.
Published: May 2019

A new model for mean velocity profile of turbulent water flow with added drag-reducing surfactants is presented in this paper. The general problem of drag due to frictional resistance is reviewed and drag reduction by the addition of polymers or surfactants is introduced. The model bases on modified Prandtl's mixing length hypothesis and includes three parameters, which depend on additives and can be evaluated by numerical simulation from experimental datasets. The advantage of the model in comparison with previously reported models is that it gives uniform curve for whole pipe section and can be determined for a new surfactant with less necessary measurements. The use of the model is demonstrated for surfactant Habon-G as an example.
Zone Method for Representing Relaxation Characteristics of Viscoelastic Materials
Authors: Koenigsberg William , Selverian John H.
Published: May 2019

Exponential integral functions were fitted to relaxation data obtained from tensile and shear loading of an asphalt-sand mixture at different temperatures. This approach yields a better fit to the experimental data than the traditional Prony series and provides physical insight into essential characteristics of the relaxation processes that govern the asphalt-sand mixture. We expect that using this model beyond the time range covered by the experimental data would result in a significantly better representation of the material behavior than would extrapolation of the Prony series fit.
Effect of Electric Fields on the Rheological Properties of the Isotropic Phase of phic/p-Xylene Solutions
Authors: Menna Todd J. , Filisko Frank E. , Lynch Rachel A.
Published: May 2019

The effect of high ac electric fields upon a liquid crystalline polymer solution, poly(n-hexyl isocyanate) in p-xylene, is examined. The results show that the solutions exhibit an increase in rheological properties proportional to the strength of the field at concentrations well below those exhibiting liquid crystalline behavior. The effects of frequency and field strength are examined as a means to explain this previously unreported phenomenon.
Influence of an Ultrasonic Treatment on the Structure and Flow Behaviour of Oxide Ceramic Masses
Authors: Götz Joachim , Rewesa Lars , Walch Michael , Geißler Adam
Published: May 2019

Oxide ceramic masses are used for catalysts and catalyst carriers. For a reliable processing hydrocolloids (e. g. cellulose) are usually added in order to decelerate demixing phenomena. Oxide ceramic masses react to simple shearing with hardening (peptisation: increase of the shear stress with the shear deformation) [1]. The present study analyses, if an ultrasonic treatment has also an impact on the structure, the shelf-life (in the green state), the correlated flow behaviour of oxide ceramic masses and presumably (not tested) the mechanical properties in the hardened, sintered state. The idea of using ultrasonic treatment is to change the microstructure (see below) and, therefore, to minimise or even give up the standard addition of stabilizers to minimize demixing in aqueous oxide ceramic suspensions. Besides the additional costs of an extra process unit, stabilisers cause often deteriorated mechanical properties (porosity, crack behaviour) of the ceramics in the hardened state after the sintering. Therefore, pump experiments (apparent viscosity), oscillatory (G´ and G´´) and steady shear experiments (h), particle-size analysis (particle-size distribution, agglomerate strength), light microscopy, decanting experiments and pH-determinations have been performed. The obtained results show, that the hardening of the apparent viscosity (derived from the flow) during pump experiments with simultaneous ultrasonic treatment in a flow cell is combined with an increase of the fine fraction, the formation of enlarged, but smoother agglomerates, the change of the pH-value and the evolution of a three-dimensional network (gelling). All these processes increase both the amount of bound/immobilised (chemically or physically bound by or onto the solid-surfaces) and of retained water (interior of agglomerates and/or the pores of the flowand ultrasonic-induced network). This means that the volume fraction of the rheologically "free" water decreases and simultaneously the effective solid volume fraction increases. With respect to the concept of the rheologically effective solid fraction this is combined with an increasing viscosity. At the same time the tendency of demixing decreases significantly. Thus, by an appropriate combination of shear flow and ultrasonic treatment, the aqueous oxide ceramic suspensions are stabilised and a reliable processing of the initially problematic solid/fluid mixtures can be realised without stabilisers (eluding their negative consequences with respect to the quality of the sintered state).
Ultrasonic Dynamic Mechanical Analysis of Polymers
Authors: Lionetto Francesca , Montagna Francesco , Maffezzoli Alfonso
Published: May 2019

The propagation of ultrasonic waves in polymers depends on their viscoelastic behaviour and density, resulting significantly affected by phase transitions occurring with changing temperature and pressure or during chemical reactions. Therefore, the application of low intensity ultrasound, acting as a high frequency dynamic mechanical deformation applied to a polymer, can monitor the changes of viscoelastic properties associated with the glass transition, the crystallization, the physical or chemical gelation, the crosslinking. Thanks to the non-destructive character (due to the very small deformation amplitude), low intensity ultrasound can be successfully used for polymer characterization. Moreover, this technique has a big potential as a sensor for on-line and in-situ monitoring of production processes for polymers or polymer matrix composites. Recently, in the laboratory of Polymeric Materials of Lecce University a custom made ultrasonic set-up for the characterization of polymeric material, even at high temperatures, has been developed. The ultrasonic equipment is coupled with a rotational rheometer. Ultrasonic waves and shear oscillations at low frequency can be applied simultaneously on the sample, getting information on its viscoelastic behaviour over a wide frequency range. The aim of this paper is to present the potential and reliability of the ultrasonic equipment for the ultrasonic dynamic mechanical analysis (UDMA) of both thermosetting and thermoplastic polymers. Three applications of UDMA to different polymeric systems will be reviewed, concerning the cross-linking of a thermosetting resin, the crystallisation from melt of a semicrystalline polymer and the water sorption in a dry hydrogel film. From the ultrasonic velocity and attenuation measurements, the viscoelastic properties of the tested polymers are evaluated in terms of complex longitudinal modulus and compared with the results of conventional dynamic mechanical analysis, carried out at low frequency.
Hydrogen effects on mechanical performance of nodular cast iron
Authors: Forsström Antti , Yagodzinskyy Yuriy , Hänninen Hannu
Published: May 2019

The KBS-3 method for long-term disposal of spent nuclear fuel is designed with an external self-standing copper shell, which provides the most important barrier against corrosion and escape of radionuclides, and an internal nodular cast iron insert, which provides the load-bearing structure against external loads. The material intended for the load-bearing insert is ferritic nodular cast iron EN 1563 grade EN-GJS-400-15U. In this paper, hydrogen uptake and sensitivity to hydrogen-induced cracking of the cast iron were studied using tensile testing under continuous electrochemical charging in 1 N H2SO4 solution. Hydrogen uptake was measured by using the thermal desorption method. It was found that the hydrogen desorption profile manifests three distinct peaks at initial locations of 400, 500, and 700 K with a heating rate of 6 K/min. Plastic deformation results in a remarkable increase of the 400 K peak, which indicates hydrogen uptake during deformation. In the constant extension rate tests (CERT) and the constant load tests (CLT), electrochemical hydrogen charging reduced markedly the elongation to fracture and time to fracture, respectively. In CLT, hydrogen charging increased dramatically the creep rate at the applied load of about 0.7 yield stress. Ligaments between the graphite nodules exhibit brittle cleavage facets in the presence of hydrogen, while the ligaments show a characteristic ductile appearance of shear and small dimples when testing in air or distilled water. The obtained results are discussed in terms of the known mechanisms of hydrogen-induced cracking and the role of the graphite nodules in the embrittlement of ductile cast iron.
Data Curator’s Roles and Responsibilities: An International Perspective
Authors: Tammaro Anna Maria , Matusiak Krystyna K. , Sposito Frank Andreas , Casarosa Vittore
Published: May 2019

The data-intensive research environment and the movement towards open science create demand for information professionals with knowledge of the research process and skills in managing and curating data. This paper is reporting the findings from a multiyear study entitled “Data curator: who is s/he?” initiated by the Library Theory and Research (LTR) Section of the International Federation of Library Associations (IFLA). The study aimed to identify the roles and responsibilities of data curators around the world and also focused on the terminology used to describe the new professional roles. The following questions were posed: R1: How is data curation defined by practitioners / professional working in the field? R2: What terms are used to describe the roles for professionals in data curation area? R3: What are primary roles and responsibilities of data curators? R4: What are educational qualifications and competencies required of data curators? To answer the research questions, the research team performed a comprehensive literature review and vocabulary analysis and conducted an empirical study using mixed-methods design. The study consisted of three stages: 1. Literature review and vocabulary analysis 2. Content analysis of position announcements 3. Interviews with professionals working in data curation and research data management- Findings confirm the results from previous research about the lack of common terminology and a variability of the position titles. The concept of data lifecycle highlighted the important role of data curators. However this study also found that many positions in practice were held by non library professionals. The findings indicate that data curation is an evolving sociotechnical practice that involves not only technical systems and services structured around research data life cycle but also a range of social activities around community building.
Japanese subject markers in linguistic change: A quantitative analysis of data spanning 90 years and its theoretical implications
Authors: Nambu Satoshi
Published: May 2019

Based on a statistical analysis of a corpus data from the period of 1915–2005, this article discusses two variants for a subject marker in Japanese, and argues that it is a case of linguistic change in progress. While representing effects of three linguistic factors on the use of the variants, the chronological observation of each factor revealed that this phenomenon demonstrates the Constant Rate Effect. The quantitative data also provides firm evidence for effects of other independent diachronic changes on the current phenomenon, pushing the change further by shrinking the linguistic environment for the dying-out variant. Dissecting the relationship between those diachronic changes and the current phenomenon in a quantitative manner, the findings of the study reveal that the two competing hypotheses in theoretical syntax properly capture the essential syntactic properties of the phenomenon in the contemporary Japanese and the discrepancy of the two accounts is attributable to their data reflecting a different stage of its ongoing change.
Counterion effect on sulfonatocalix[n]arene recognition
Authors: Garcia-Rio Luis , Basílio Nuno , Francisco Vitor
Published: May 2019

Sulfonatocalixarenes, like other ionic receptors, possess counterions that can affect the molecular recognition process. In the present review it is shown that the competitive effect of the alkaline cations frequently used as counterions determines not only the magnitude of the external guest association constant, but also the stoichiometry of the complexes. Experimental evidences are shown about the interaction of the counterions with sulfonatocalixarene, allowing to quantify its association equilibrium constants. The counterions recognition will be a competitive process that must be taken into account when investigating the interaction of calixarenes with an external guests. When the external guest is a neutral molecule it will be possible to form ternary complexes where the counterion shows a competitive and cooperative effect. By increasing the size of the receptor, sulfonatocalix[6] and sulfonatocalix[8]arene, the complexity of the system is increased due to the formation of counterion complexes with stoichiometries 1:1 and 1:2. In the presence of an external guest, the formation of heteroternary complexes with 1:1:1 stoichiometries including a counterion and an organic cation will be possible.
Präzise Vermessung von Zuckerrübenkeimlingen mit dem phenoTest
Authors: Rehak Markus , Haßler Ulf , Grulich Tobias , Wörlein Norbert , Porsch Felix , Götz Yvonne , Wolff Antje
Published: May 2019

Die Keimfähigkeit von Zuckerrübensamen wird im Allgemeinen nach den International Rules for Seed Testing der International Seed Testing Association (ISTA) bestimmt. Mit dieser visuellen, sehr personal- und kostenintensiven Methode lässt sich Saatgut wegen fehlender Messwerte nur subjektiv bewerten. Mit dem phenoTest wurde ein vollautomatisches Phänotypisierungs-System entwickelt, das mittels 3D-Computertomographie eine objektive, zerstörungsfreie und quantitative Bestimmung von Keimfähigkeitsparametern erlaubt. Die automatisierte Bildauswertung muss hierbei mit der für den hohen Durchsatz notwendigen geringen Auflösung der CT-Aufnahme sowie der Tatsache, dass zu trennende Strukturen keinen Kontrastunterschied aufweisen, zurechtkommen. Im Vergleich zur ISTA-Methode lassen sich durch den phenoTest nicht nur exaktere, sondern auch neue Qualitätsmaße bestimmen.
From expressionless to impressionist: Exploring the link between neurological disease and artistic style in painters
Authors: Konder Ricarda M.
Published: May 2019

This paper discusses the relationship between various types of neurological disease and stylistic changes in painters. By first outlining the hypothesized neuroanatomical bases of creativity, the discussion then relates localized brain damage to various stylistic changes in painters and previously non-artists. It also explores artistic style in the context of more global neurological damage, such as dementias and neurotransmitter imbalances.The literature suggests that focal neurological insults (such as strokes or head injuries) may more often lead to focal deficits in painters, such as the loss of visuospatial ability or partial hemineglect. More widespread neurological damage may be associated with more global stylistic changes; for example, dopamine replacement therapy for Parkinson’s disease has been shown to produce a more impressionist painting style in numerous recorded artists. In several case studies, brain damage actually led to the emergence of de novo artistic ability.While these changes in artistic style may not be rigidly predictable based on the limited literature available, this paper demonstrates that both artists and non-artists may experience significant changes in artistic style after neurological disease. Patient narratives also suggest that painting may serve as an empowering personal coping and communication strategy, aiding patients in navigating their complex illnesses.
Computed tomography scan can be misleading in the lateralisation of aldosterone excess
Authors: Leksic G , Alduk A M , Molnar V , Haxhiu A , Haxhiu A , Balasko A , Knezevic N , Dusek T , Kastelan D
Published: May 2019

Primary aldosteronism (PA) is characterised by aldosterone hypersecretion and represents a common cause of secondary hypertension. During diagnostic evaluation, it is essential to determine the aetiology of PA since the treatment of unilateral and bilateral disease differs significantly. Adrenal vein sampling (AVS) has been implemented as a gold standard test for the diagnosis of PA subtype. However, due to the AVS complexity, costs and limited availability, many patients with PA are being treated based on the computed tomography (CT) findings. In this article, we present two patients with discrepant CT and AVS results, demonstrating that AVS is the only reliable method for localising the source of aldosterone excess.

Learning points:

CT is an unreliable method for distinguishing aldosterone-producing adenoma (APA) from bilateral adrenal hyperplasia (BAH).

CT can be misleading in defining lateralisation of the aldosterone excess in case of unilateral disease (APA).

AVS is the gold standard test for defining the PA subtype.
Threshold Inhibition of Methyltransferase G9a/Glp Exacerbates Neuropathic Hypersensitivity through Mediating GRIN2B Methylation
Authors: Wang Fuzhou , Wang Xian , Wu Haibo , Ma Jianming , Xu Shiqin , Li Shengmei , Bao Senzhu
Published: May 2019

Background In this study, we investigated whether G9a related DNA methylation and histone modification is involved in the transcription alteration of NR2B following peripheral nerve injury and subsequently contributes to pain facilitation of G9a inhibition.
 
Methods After approval by the institutional ethical committee on pain research in conscious animals, C57BL/6 mice were used to induce neuropathic pain with spared nerve injury (SNI). G9a/Glp expression, GRIN2B gene 5’-regulatory region CpG sites methylation profile, as well as NR2B expression in the spinal dorsal horn following SNI was detected with immunofluorescence, bisulfite sequencing, and western blot, respectively. For mechanism study, threshold doses of G9a/Glp inhibitors BIX01294/UNC0638 or direct DNA demethylation agent 5-Aza was intrathecal injected through the pre-buried catheter daily in bolus for 3 days, G9a/Glp and its enzymatic substrate H3K9me2/H3K9me3 expression, GRIN2B gene methylation alteration, as well as NR2B expression were observed. Nociceptive behavior was depicted in response to von Frey filaments following SNI with or without intrathecal BIX/UNC and 5-Aza treatments.
 
Results Ipsilateral mechanical withdrawal threshold rather than thermal withdrawal latency prominently decreased and peaked at day 7 to 14 post SNI. Besides, nerve injury consistently increased G9a/Glp, H3K9me2 expression, GRIN2B gene 5’-regulatory region CpG sites methylation, as well as NR2B expression in the spinal dorsal horn at day 7 post SNI. Furthermore, either G9a/Glp inhibition by BIX/UNC or H3K9me2 blockade by 5-Aza independently reversed GRIN2B gene high methylation, followed with disinhibition of NR2B transcription inhibition. Consistent with molecular changes, either BIX/UNC or 5-Aza further worsens nerve injury-induced allodynia.
 
Conclusion G9a/Glp contributes to the pathogenesis of neuropathic pain via methylating GRIN2B gene affecting NR2B transcription. G9a/Glp at an elevated setpoint may prevent the over-sensitization following peripheral nerve injury.
Room Sharing in Hospitalized Children With Bronchiolitis and the Occurrence of Hospital-Acquired Infections: A Prospective Cohort Study
Authors: Bekhof Jolita , Wessels Mirjam , ten Velde Eline , Hoekstra Minke , Langenhorst Veerle , Bruijnesteijn Lesla , Brand Paul L.P. , Ruijs Gijs J.H.M.
Published: May 2019

OBJECTIVES:

To determine the prevalence and severity of hospital-acquired infections (HAIs) in children hospitalized for bronchiolitis when patients share a room, irrespective of the causative virus.

METHODS:

A prospective cohort study during 4 winter seasons (2012–2016) was conducted in a Dutch general pediatric ward including otherwise healthy children <2 years of age hospitalized for bronchiolitis. Patients shared a 1-to-4–bed hospital room irrespective of virological diagnosis. The main outcome measures were HAIs assessed through multiplex polymerase chain reaction and disease severity.

RESULTS:

HAIs occurred in 28 of 218 included patients (12.8%), most frequently with rhinovirus (17 of 28; 60.7%). In 3 (10.7%) of 28 HAIs, the same virus was identified in roommates. Only 1 patient became cross-infected with respiratory syncytial virus, although this patient never shared a room with a patient infected with respiratory syncytial virus. HAI was not associated with more severe disease. The median length of hospitalization was 3.5 days (interquartile range [IQR] 1–6) compared with 3 days (IQR 2–6; P = .86); the number of PICU admissions was 0% versus 5.3% (P = .21); the median days of oxygen supplementation was 2.5 (IQR 1–4) versus 2 (IQR 1–4; P = .58); the median days of tube feeding was 2 (IQR 0–5) versus 2 (interquartile range: 0–5; P = .77); and the readmission rate was 0% versus 5.8% (P = .19) in patients with and without HAI, respectively.

CONCLUSIONS:

HAIs among patients with bronchiolitis are common but not associated with more severe disease. Room sharing with appropriate hygiene does not play a relevant role in the transmission of viruses between patients with bronchiolitis, regardless of the viruses involved. On the basis of these findings, we suggest that room sharing of patients with bronchiolitis is safe.
Physicians’ and Nurses’ Perspectives on the Decision to Perform Lumbar Punctures on Febrile Infants ≤8 Weeks Old
Authors: Aronson Paul L. , Schaeffer Paula , Fraenkel Liana , Shapiro Eugene D. , Niccolai Linda M.
Published: May 2019

OBJECTIVES:

There is wide variation in the decision of whether to perform lumbar punctures (LPs) on well-appearing febrile infants ≤8 weeks old. Our objectives were to identify factors that influence that decision and the barriers and facilitators to shared decision-making about LP with parents of febrile infants.

METHODS:

We conducted semistructured interviews with 15 pediatric and general emergency medicine physicians and 8 pediatric emergency medicine nurses at an urban, academic medical center. Through interviews, we assessed physicians’ practices and physicians’ and nurses’ perspectives about communication and decision-making with parents of febrile infants. Two researchers independently reviewed the transcripts, coded the data using the constant comparative method, and identified themes.

RESULTS:

Five themes emerged for factors that influence physicians’ decisions about whether to perform an LP: (1) the age of the infant; (2) the physician’s clinical experience; (3) the physician’s use of research findings; (4) the physician’s values, particularly risk aversion; and (5) the role of the primary care pediatrician. Barriers and facilitators to shared decision-making identified by physicians and by nurses included factors related to their perceptions of parents’ understanding and acceptance of risks, parents’ emotions, physicians’ assessment of whether there is clinical equipoise, and availability of follow-up with the primary care pediatrician.

CONCLUSIONS:

Differences in physicians’ values, use of research findings, and clinical experience likely contribute to decisions of whether to perform an LP on well-appearing febrile infants. Incorporation of parents’ preferences through shared decision-making may be indicated, although there are barriers that would need to be overcome.
Climatogenic reaction of Robinia pseudoacacia and Pinus sylvestris within Northern Steppe of Ukraine
Authors: Gritsan Y. I. , Sytnyk S. A. , Lovynska V. M. , Tkalich I. I.
Published: May 2019

Climatic changes in the environment are becoming more noticeable each year. Nonetheless, trends in the reaction of radial growth of forest trees to climate change should be studied in different climatic regions due to significant local variability in climatic conditions which are specific for any particular area. We conducted a correlation analysis of the relationship between the parameters of radial increment of black locust (Robinia pseudoacacia L.) and Scots pine (Pinus sylvestris L.) and meteorological factors of the environment in forest areas located in thenorthern steppe zone of Ukraine. We performed surveys in plantations of black locust, growing in hill slope and interfluve areas and also in sandy terrace plots of Scots pine. Over the period of intense vegetatative growth, black locust requires moisture 50% higher than the norm, and Scots pine 43% higher than the norm. It was determined that maximum increment for the studied plants occurred under the influence of a combination of factors involving reduction of the air temperature by 2.6–2.7 °С below the norm for black locust and by 2.3–2.5 °С for Scots pine. During the period of lower vegetative activity, Scots pine demonstrated lower sensitivity compared to black locust. This paper provides a statistical characteristic of the radial increment of trees in the conditions of changes in meteorological factors which limit their growth. The article provides data on multiple correlation of radial increment of the tree stands in relation to growth locations; demonstrates correlation dependency of radial increment of the studied trees on the precipitation and mean monthly temperatures over different time periods and during particular months. Radial increment of Scots pine exhibited most positive correlation with the total of precipitations throughout the period. For the stands of black locust, correlation coefficients were higher and distinguished by both positive and negative values. In the current increment of this species, a negative correlation relation was observed with the total precipitation in July, August and September, and positive correlation with the remaining months of the year. By contrast, radial increment of black locust and Scots pine positively correlated with air temperature during all time periods and particular months.
Morphological variability of Bembidion aspericolle (Coleoptera, Carabidae) populations in conditions of anthropogenic impact
Authors: Komlyk V. O. , Brygadyrenko V. V.
Published: May 2019

Bembidion (Talanes) aspericolle (Germar, 1829) is a Western Palearctic species which lives on the shores of the Atlantic Ocean, the Mediterranean, Black and Caspian Seas and saline inland habitats from Central Europe to Central Asia. Anthropogenic impact is one of the most important environmental factors affecting the morphological variability of ground beetles. The objective of our research is assessment of the morphological variability of this species in three ecosystems differing by intensity of anthropogenic impact. 13 linear characteristics, one angular characteristic, density of pores on the prothorax and elytra, contrast of spots on the beetles’ elytra were measured, and 6 morphometric indices were calculated. The mean value of body length in females is more than in males in the studied populations. In the ecosystem with high anthropogenic pressure, female body length is shorter by 3.7% and elytra length is shorter by 6.0% than in females in the ecosystem with low anthropogenic impact. Differences between populations in the body length of males are not significant. In the ecosystem with high anthropogenic transformation, sexual dimorphism is observed only on head and prothorax width. The ratio of maximum width of elytra to maximum prothorax width decreases significantly with increasing anthropogenic load. The impact of anthropogenic factors on the ecosystem produces significant changes in elytra length and head width of B. aspericolle and in four of the six morphometric indices. It is reasonable to use these morphometric characteristics of B. aspericolle adults in bioindication. The complex of anthropogenic factors does not have a significant impact on the value of anterior and posterior angles of prothorax, density of prothorax and elytra puncturing and contrast of the light spots at the top of the elytra. The sex of the specimen influences all linear characteristics. The absence of significant differences in morphometric indices between males and females shows that the body proportions of the beetles remain unchanged and only linear dimensions vary. Research on the morphological variability of B. aspericolle is important for understanding microevolutionary processes in populations of beetles under anthropogenically induced changes in the environment.
The current state of the population of the golden potato cyst nematode Globodera rostochiensis (Nematoda, Heteroderidae) in the northwest of Ukraine
Authors: Sukhomlin K. B. , Koshirets V. M. , Zinchenko M. O. , Biletskiy Y. V. , Zinchenko O. P.
Published: May 2019

The golden potato cyst nematode (GPCN) Globodera rostochiensis (Wollenweber, 1923) Skarbilovich, 1959 is a highly specific parasite of the roots of the nightshade plants (Solanaceae). Thus, the state of the pest population demands constant monitoring and control of distribution and numbers. The distribution of G. rostochiensis in Volyn region of Ukraine was studied in 2008–2018 using the data of the state institution the Volyn Regional Phytosanitary Laboratory. The present article gives the analysis of the study results. The disease foci were detected by visual above-ground inspection of potato plantings, also by manually collecting soil samples before planting the potatoes and after harvesting, and consequently analyzing theme. The initial (pre-planting) and conclusive (after harvest) population density of GPCN in the soil was determined by the number of cysts and the mean number of larvae and eggs in cysts obtained from 100 cm3 of soil. Cysts were isolated from soil samples by the standard funnel flotation method. The dead and living larvae were identified visually by the shape of the body and the state of internal organs. According to the results of assessing pre-planting and post-harvest nematode numbers in soil, the reproduction coefficient Рf/Рі was calculated. In Volyn region, G. rostochiensis was first observed in 1968 on farmland and since then, the parasite has spread. Pest foci were recorded in 15 districts of the region in 303 settlements on the area of 946.123 hectares. It was however found that during the latest decade, the area of soils affected by G. rostochiensis in Volyn region decreased by 147.647 hectares. The largest infected areas (over 100 ha) were located in Kovel, Rozhyshche and Manevistky districts, the least infected area was observed in Ivanychi district of the region. The pest was not found in Lutsk district. The highest infection rate was recorded in Rozhyshche district. The highest ratio of viable cysts was observed in the soils of Volodymyr-Volynsky and Rozhyshche districts. The soils of the southern districts (located in the natural zone of forests and steppe) of the region demonstrated 1.5 times higher infection rates compared to soils of the northern districts (in the natural zone of mixed forests). The soils of the southern districts also harboured stable and strong pest populations. The pre-planting soil infection rates proved to directly depend on the reproduction coefficient of GPCN. If the values of Рі, initial infection rate, were lower than 1,000 larvae and eggs per 100 cm3, the reproduction coefficient was 1.18. Increase in the pre-planting infection rate to 2,000 eggs and larvae per 100 cm3 did not affect the reproduction coefficient. At approximately 5,000 eggs and larvae per 100 cm3 the reproduction coefficient exceeded 2, which should be considered in developing the pest control measures.
Comparison of selected characteristics of cultivarsand wild-growing genotypes of Sambucus nigra in Slovakia
Authors: Horčinová Sedláčková V. , Grygorieva O. , Vergun O. , Vinogradova Y. , Brindza J.
Published: May 2019

In view of global changes, it is necessary to consider plant breeding as a process of developing new varieties and cultivars for present and future needs, with an emphasis on improving their quantitative and qualitative characteristics. The aim of this study was to compare wild-growing genotypes of elderberry (Sambucus nigra L.) with three registered cultivars Haschberg, Sambo and Bohatka in selected economic traits in Slovakia. Characters of selected genotypes and cultivars were tested in dynamics of inflorescences and fruit clusters, the morphological parameters such as the weight of fruit clusters, weight and number of drupes and weight of cluster without drupes. On the cv. Haschberg we evaluated the number of inflorescences for each individual plant for a period of three years. A high number of inflorescences was established in the first 3 years of plant growth. This is evidenced by the measurements from the 2-, 3-, 4- and 5-year old plants with the number of inflorescences on average 21.3–25.7, 42.2–51.0, 65.1–73.7 and 99.0, respectively. The cultivars matured about two to three weeks later compared with wild-growing genotypes. The weight of the fruit clusters and the weight of drupes is an important trait in terms of plant production and efficiency of cultivation. For wild-growing genotypes, we also identified genotypes with a high weight of fruit clusters (111.1 g – SN-48) and weight of drupes (105.5 g – SN-48), which are determinant properties for selection of new genotypes for plant breeding and cultivation. The yield of juice is an important indicator for technological processing of elderberry fruit. For the cultivars the juice yield was found to range from 78.7% (cv. Sambo) to 82.9% (cv. Haschberg). We determined that the yield of juices of wild-growing genotypes ranged from 77.9–86.0%. The cultivar Haschberg had a better set of morphological traits compared to wild-growing genotypes, even though it was possible to find comparative genotypes in some characteristics. The results and knowledge obtained are useful for future breeders, cultivators, and processors of elderberries.