bluuebunny/crossref_metadata_2025 huggingface dataset:
Bond Mechanism of FRPs Externally Applied to Curved Masonry Structures: Experimental Outcomes and Numerical Modeling
Authors: Fabbrocino Francesco , Formisano Antonio , Grande Ernesto , Milani Gabriele
Published: August 2019

The studies contained in the current literature particularly emphasize the importance of the role of the local bond mechanism on the global performance of fiber reinforced polymer systems (FRPs) employed for the strengthening and the rehabilitation of structures. Nevertheless, although several applications of FRPs involve curved masonry structures (arches, vaults, domes, etc.), the bond mechanism of FRPs applied on masonry samples with curved substrates is a topic still scarcely investigated and the actual guidelines do not provide specific design formulas. The aim of the present paper is to analyze the main features characterizing the bond behavior of FRPs externally applied to masonry specimens with a curved substrate configuration throughout a simple modeling approach based on the interface concept. Particular consideration is devoted to the development of suitable constitutive laws for the FRP/masonry interface. Considering case studies derived from the current literature, consisting of shear-lap bond tests of curved masonry specimens characterized by different curvatures of the bonded surface and different strengthening configurations, numerical analyses are carried out in order to emphasize the ability of the model to capture the bond behavior of FRP applied on curved masonry substrates.
Experimental Investigation on the Bond Behaviour of Basalt TRM Systems - Influence of Textile Configuration and Multi-Layer Application
Authors: Misseri Giulia , Stipo Gianfranco , Galassi Stefano , Rovero Luisa
Published: August 2019

Textile Reinforced Mortars (TRM) include a series of innovative strengthening systems suitable for conservation interventions since inorganic matrixes, instead of polymeric resins, are employed. Recent research supported the definition of guidelines on testing methods for TRM systems applied to masonry, but further investigation is needed to clear out the role played by the numerous factors affecting the strengthening capacity. In this study, an experimental campaign on basalt-fibre TRM systems was carried out. A series of tensile and single-shear bond tests are compared. Samples differ for fibre reinforcement ratio, textile layout and the number of textile layers, while the lime-based mortar matrix is the same for all specimens. For tensile tests, results show that, after a mortar-cracking phase, a third, substantially linear phase, during which the textile response is dominant, occurred for specimens failed both for textile tensile rupture and textile slippage. For shear bond tests, results showed that increasing the reinforcement ratio tightening textile mesh is not as beneficial as increasing textile layers, i.e. active bond surfaces.
Influence of Alkaline Environments on the Mechanical Properties of FRCM/CRM and their Materials
Authors: Rizzo Valeria , Bonati Antonio , Micelli Francesco , Leone Marianovella , Aiello Maria Antonietta
Published: August 2019

Fabric Reinforced Mortar (FRCM) used as Externally Bonded Reinforcements (EBR), provide a sustainable solution for retrofitting and repair of existing masonry structures. They are commonly made by fibrous meshes embedded in a cementitious/hydraulic lime matrix. This technique represents a valid alternative to the well-known FRP (Fiber Reinforced Polymer) composites, which show some limitations in heritage masonry applications. In this scenario, a new system known as CRM (Composite Reinforced Mortar) has been developed in the last years. In this system, a pre-cured FRP grid is utilized as internal reinforcement in a mortar layer. The system reproduces the traditional technique of reinforced plaster, where the steel grid is substituted by a non-metallic one. In masonry applications high compatibility with the substrate, sustainability and removability are commonly required in heritage construction. These goals are not easily achieved by using fibers immersed into a polymeric resin. Moreover, the inorganic matrix ensures the transpiration of substrates and consequently a higher durability of the whole strengthened system is expected. On the other hand, the recent use of these new materials in civil engineering needs appropriate design guidelines. The proposed paper focuses attention on the initial results of a large experimental study on the durability of FRCM/CRM systems and their single components (dry glass fibers, resin, pre-cured FRP grid and mortar). In particular, the influence of three alkaline environments solutions was studied. Exposure conditions were stressed by increasing the temperature of the three aqueous solutions. The mechanical retention of tensile properties was measured by performing direct tensile tests after different exposure times.
NURBS-Based Upper Bound Limit Analysis of FRP Reinforced Masonry Vaults through an Efficient Mesh Adaptation Scheme
Authors: Grillanda Nicola , Chiozzi Andrea , Milani Gabriele , Tralli Antonio
Published: August 2019

Masonry vaults represent one of the typical structural typologies in historical masonry buildings. The study of the ultimate behavior of masonry vaults, together with the need to design adequate retrofitting techniques, is of high relevance in the optics of the preservation of the cultural heritage. In this paper, a new approach for the limit analysis of masonry construction is applied to FRP reinforced masonry vaults. This approach relies on the representation of geometry through NURBS surfaces, upper bound formulation of limit analysis, idealization of the structure as an assembly of rigid bodies with dissipation allowed only along interfaces, and optimization by means of a mesh adaptation scheme. The presence of FRP strips can be taken into account in easy way, because they can be included simply by adding NURBS surfaces and assigning them an adequate delamination stress value. The efficient mesh adaptation is performed by means of a Prey Predator Algorithm, which has been proven to be very suited for these problems. The strength of the proposed method lies in an accurate estimation of load-bearing capacity and collapse mechanism obtained with a model which requires a very low computational effort.
On Collapse Behavior of Reinforced Masonry Domes under Seismic Loads
Authors: Grillanda Nicola , Chiozzi Andrea , Milani Gabriele , Tralli Antonio
Published: August 2019

In this paper, the first result on the collapse behavior of reinforced masonry domes under seismic loads is presented. A certain masonry dome is modeled through NURBS surfaces, which have the great advantage to represent accurately complex geometries. The obtained NURBS model is imported in the MATLAB® environment, in which an initial NURBS mesh is defined. An upper bound limit analysis is applied: each element is idealized as rigid block and eventual plastic dissipation is allowed only along element edges. The minimum of the kinematic multipliers is found by optimizing the NURBS mesh (i.e. modifying the position of fracture lines) through a meta-heuristic algorithm (e.g. a Genetic Algorithm). A reinforcing system made by FRCM fibers is included through additional NURBS surfaces: each new surface represents a strip and exhibits only a tensile contribute in the evaluation of plastic dissipation. The dome of the church of Anime Sante, which collapsed during the L’Aquila earthquake in 2009, is considered as meaningful case study. A standard disposition of FRCM fibers, typically designed for incrementing the vertical load bearing capacity, has been hypothesized. The reinforced dome is analyzed under a horizontal acceleration linear in height and constant in plane and a comparison between the unreinforced and the reinforced case is presented.
Retrofit of Masonry Buildings through Seismic Dampers
Authors: Jafarzad Eslami Babak , Del Grosso Andrea
Published: August 2019

After the recent earthquakes occurred in some cities in Iran, such as Bam and Kermanshah, the engineering community was forced to pay special attention to the seismic vulnerability of traditional structures. Unreinforced masonry walls exhibit poor seismic performance under moderate and high seismic demand, due to the rapid degradation of stiffness. The development of effective techniques for the strengthening of these walls is an urgent need. The Base Isolation System (BIS) provides solutions to mitigate seismic hazard [1]. In this work, the seismic vulnerability of heritage masonry walls is assessed by conducting extensive numerical studies on both unreinforced (fixed-base) and reinforced (Base Isolation System) masonry walls. In this manner, modeling and analysis are conducted using standard finite element software, ABAQUS 6.13, and results of fixed-base masonry wall and similar base-isolated walls retrofitted with laminated rubber bearings are compared. Nonlinear time history analyses (using the actual Bam earthquake), which enable description of the pre-peak and post-peak behavior of walls, have been used to describe the behavior of structures.Finally, comparison of the failure modes between unreinforced and reinforced masonry walls reveals efficiency of using the rubber bearing isolation (passive control vibration devices) for a reduction in acceleration and an increase in the structural resistance to earthquake excitations [2].
Shake Table Tests on a Masonry Structure Retrofitted with Composite Reinforced Mortar
Authors: de Santis Stefano , de Felice Gianmarco , Di Noia Garis Lorenzo , Meriggi Pietro , Volpe Marika
Published: August 2019

Recent earthquakes have dramatically shown the seismic vulnerability of existing masonry structures and highlighted the urgent need of developing suitable strengthening solutions. In order to gain an improved understanding of the seismic response of masonry constructions and of the most appropriate technologies for their retrofitting, a shake table test was performed on a full-scale U-shaped tuff masonry structure, provided with an asymmetric plan with openings and with an inclined roof. The specimen was tested unreinforced and then repaired and retrofitted with composite reinforced mortar (CRM), comprised of a glass fibre reinforced polymer mesh applied with a lime mortar. Natural accelerograms were applied with increasing scale factor to collapse. Results provided information on the dynamic behaviour of masonry structures strengthened with CRM and on the enhancement of seismic performance provided by the retrofitting work.
The Generalized Density Evolution Equation for the Dynamic Analysis of Slender Masonry Structures
Authors: Lucchesi Massimiliano , Pintucchi Barbara , Zani Nicola
Published: August 2019

Within the framework of structural dynamics, the article deals with the problem ofdetermining at a given moment the probability density function of certain quantities of interest,based on the uncertainties about the initial data, the structure characteristics and the applied loads.The proposed method uses the so-called principle of preservation of probability, and leads towriting a linear partial differential equation for any quantity whose probability density function hasto be determined.
Shear Behavior of Multi Leafs Masonry Panels with Transversal Connections
Authors: Cascardi Alessio , Leone Marianovella , Aiello Maria Antonietta
Published: August 2019

The historical masonry buildings are generally characterized by a load-bearing structure constituted by walls that should resist to both gravitational and horizontal actions. In several existing constructions, masonry panels are made by two external leafs with higher mechanical properties and an inner core with very low, or even negligible, mechanical characteristics. In some cases the connection between the external leafs was provided by inserting a certain number of bricks in the transversal direction (namely diatones); while sometimes, the leafs were totally independent. Often in the case of horizontal forces, as those due to earthquakes, the multi-leafs walls collapse has been observed, because of the leafs separation. Nowadays, there are different connecting systems available in the market and utilized to guarantee the collaboration of the external leafs, in order to finally improve the wall bearing capacity.In this scenario, the present paper is aimed to investigate the shear strength of small-scale multi-leafs panels, coupled with different types of connector, such as: diatones, L-shaped glass; glass and steel rope and helical steel bars. In plane shear tests have been performed in order to evaluate the shear stress-strain relationship. The results are herein reported and discussed, aiming to determine the effectiveness of the different connections systems.
An Alternative Approach for FRCM Matrix Tensile Strength Evaluation
Authors: Bellini Alessandro , Bovo Marco , Incerti Andrea , Mazzotti Claudio
Published: August 2019

Structural retrofitting with composite materials proved to be an effective technique for rehabilitation of degraded or damaged masonry and concrete buildings. Nowadays, Fiber Reinforced Cementitious Matrix (FRCM) composites are widely used as externally bonded strengthening systems thanks to their high performance, low weight and easiness of installation. Several experimental tests and numerical studies are currently available concerning the tensile and bond behavior of FRCM systems, but a debated and still open issue concerns the methods for the mechanical characterization of the mortar used as matrix within the strengthening system. The present paper analyses and compares different test methods for determining the matrix tensile strength. Pure tensile and flexural tests have been carried out on different mortar matrix samples. In order to evaluate which is the most suitable value to be considered for a correct interpretation and modeling of the composite system, the experimental results obtained through flexural tests on standard mortar specimens have been compared with the outcomes obtained from direct tensile tests on FRCM coupons. The present study represents only a first step for the definition of the most appropriate test method for the mechanical characterization of the matrix used within FRCM strengthening systems.
Experimental Investigation on Masonry with Textile Reinforcement in Thin Bed Joints
Authors: Saenger Dorothea , Raupach Michael
Published: August 2019

The application of textile reinforcement can help to increase the load-bearing capacity of masonry building components, especially those subjected to lateral loads caused by wind, earth pressure or earthquake. The reinforcement can be applied externally or be integrated in the bed joint. The key part of an ongoing research project is to investigate the bonding and load-bearing behavior of masonry building components reinforced with textile in thin bed joints with the aim to develop reinforcing elements. With these reinforcing elements for bed joints the construction of basements and higher buildings will be more attractive with masonry. In the first part of the project, the relevant material and bond properties of preselected materials were determined, and a suitable textile was selected. In the second part, four-point bending tests on unreinforced and reinforced masonry wall specimens were carried out in order to investigate the effectiveness of bed joint textile reinforcement to increase the masonry flexural tensile strength. In the third part, a proposal for the design of prototypical reinforcing elements will be worked out. This paper deals with the two first parts of the research project.
Can Textile Reinforced Mortar (TRM) Systems Be Really Effective to Increase Compressive Strength of Masonry Panels?
Authors: Donnini Jacopo , Maracchini Gianluca , Chiappini Gianluca , Corinaldesi Valeria , Quagliarini Enrico , Lenci Stefano
Published: August 2019

The use of Textile Reinforced Mortar (TRM) systems represent a valid alternative to traditional strengthening techniques, to improve mechanical strength and seismic performance of masonry buildings. Their effectiveness has been validated by several studies [1-4]. However, the TRM contribution in the mechanical behavior of masonry walls, subjected to simple compression, has not yet been fully investigated. In this study, an experimental campaign with the objective of studying the efficiency of TRM systems, applied to clay brick masonry panels, is presented. Compression tests were conducted on clay brick masonry panels with dimensions of 250x1000x1200 mm3. Glass fiber bidirectional fabrics were applied on both sides of the panels, coupled with lime-based mortar, and connected with stainless steel helical connectors. The total thickness of the reinforcement system is 30 mm. The effect of the TRM reinforcement on the mechanical behavior of the panel is analyzed and experimental results are compared with those of unreinforced panels in terms of ultimate strength and failure modes.
Influence of Matrix Properties on FRCM-CRM Strengthening Systems
Authors: Tilocca Anna Rosa , Incerti Andrea , Bellini Alessandro , Savoia Marco
Published: August 2019

During the last decades, widespread seismic events in the Southern European zone have significantly damaged the masonry built heritage. Designers and researchers studied different techniques to increase the performance of masonry panels subjected to horizontal actions due to seismic phenomena. In particular, two of the most common strengthening systems are Fiber Reinforced Cementitious Matrix (FRCM) and Composite Reinforced Mortar (CRM). These systems are usually applied on both surfaces of the load-bearing elements in order to increase their shear strength properties. This work aims at analyzing the effects of three different matrices, comparing FRCM and CRM systems applied on double-leaf masonry panels subjected to diagonal compression test in displacement control (ASTM E519). Compressive strength and thickness of the matrices applied on the masonry substrate were investigated in order to evaluate the relationship between the performance of matrices used within composite strengthening systems (FRCM or CRM) and the density of fiber grids adopted (basalt and glass). The mechanical characterization of the different strengthening systems was performed by means of tensile and bond tests on masonry prisms. Finally, the experimental results obtained were analyzed in terms of failure modes and maximum capacity attained by strengthened panels.
Strengthening of Masonry Structures: Current National and International Approaches for Qualification and Design
Authors: Bonati Antonio , Franco Annalisa , Coppola Orsola , de Luca Giuseppina
Published: August 2019

The strong seismic events that have occurred in Italy during the past few years have shown the vulnerability of unreinforced masonry structures all over the country. The growing interest in the use of composite materials as a fast and effective way for structural strengthening pushed Italian public authorities to define common rules for qualification and design. Different guidelines are being developed at the national, but also at the international level, considering the different composite systems currently present on the market, generally constituted by continuous fibres in the form of fabrics or meshes embedded in a polymeric or inorganic matrix. The paper will summarize and compare the various assessment and design approaches of the composite system, highlighting the different aspects which characterize national and international procedures of certification.
Shape Design Enhancement of Pultruded FRP Profiles for Structures Ancillary to Masonry Constructions
Authors: Boscato Giosuè , Aldreghetti Ivano , Baraldi Daniele , Cecchi Antonella , Costantini Giorgio , Massaria Lorenzo , Scafuri Vincenzo , Tofani Italo
Published: August 2019

The historical building heritage, monumental, civil and industrial has highlighted, especially in the last decade, the high vulnerability with respect to horizontal actions. The need to design stable and strong structural systems with respect to the stresses acting in various directions has oriented research to develop lightweight technologies for structural systems, independent or ancillary, with reduced mass to mitigate the consequent applied load. In this scenario all-FRP (Fiber Reinforced Polymers) systems can be a valid alternative for new constructions and / or structural reinforcement. The scenario described above, highlights the importance of developing innovative technologies suitable for the functional and structural improvement of the existing buildings. It is necessary to define an innovative approach aimed at identifying an ad-hoc profile for the FRP pultruded profiles (currently referring to the steel shapes), which allows to capitalize the performance capabilities, limiting the main defects related to low shear stiffness of FRP pultruded material. This research analyses how the shape enhancement of the cross sections, with shape redraw, allows to increase the structural performances of FRP pultruded profiles. Experimental data of previous research on buckling behaviour of different open cross section profiles, narrow and wide flanges, have been analysed and validated by numerical approach and compared with new strengthened shapes.
Temporal Modeling of Dengue Fever: A Comprehensive Literature Review
Authors: Aswi Aswi , Cramb Susanna , White Gentry , Hu Wen Biao , Mengersen Kerrie
Published: August 2019

Dengue fever has become a major public health problem in several countries. This paper aims to review and compare a number of temporal modeling approaches that have been proposed for predicting or forecasting the occurrence of dengue fever. This review also examines influential covariates considered in these studies. A comprehensive literature search was undertaken in September 2018, using Medline (via Ebscohost), ProQuest, Scopus, and Web of Science electronic databases. The search was confined to articles in English, published in refereed journals between January 2000 and September 2018. The most popular approach to temporal modeling of dengue was found to be an autoregressive integrated moving average (ARIMA) model. A limited number of studies applied Bayesian hierarchical dynamic generalized linear models. Climatic variables were most commonly associated with dengue incidence for temporal modeling.
Platelets and Hematocrit in the Survival Model of Dengue Hemorrhagic Fever (DHF) Sufferers in Palopo
Authors: Fa'rifah Riska Yanu , Poerwanto Bobby
Published: August 2019

This study aims to apply cox regression analysis to predict the patient's survival to dengue disease occurring in Palopo. This study uses clinical data, namely the results of laboratory tests to determine the effect on the patient's healing period. Laboratory test results used are platelets and hematocrit. By using the MPLE method to obtain parameter estimation in the cox regression model, it is known that platelets have a stronger effect for patient resistance on DHF than hematocrit. This is based on the p-value obtained from the analysis less than alpha (0.05), which is equal to 0.0433. Patients who had an average platelet below normal when experiencing DHF are longer in their recovery period. In addition, patients with DHF ≤ 2 days, the probability to survive and recover was 90%.
Molecular Barcoding Based 16S rRNA Gene of Thermophilic Bacteria from Vulcanic Sites, Linow Lake, Tomohon
Authors: Suddin Simanjuntak , Mokosuli Yermia Semuel , Marcelina Welerubun , Orbanus Naharia , Ardi Kapahang
Published: August 2019

Thermophilic bacteria live at temperatures above 450 C. Many investigations focused on their potential as sources of highly active enzymes ‘termostable enzyme’ and other products such as antibiotics and compatible solutes. Lake Linow is an active volcanic lake located in Tomohon City, North Sulawesi, Indonesia. Lake Linow becomes the habitat of thermophilic bacteria. A study has been conducted to obtain isolates of thermophilic bacteria and to identifikasi berdasarkan gen 16 s RNA. Bacterial DNA extraction procedure using the Presto TM Mini gDNA Bacteria Kit Geneaid protocol, with modifications. Amplification of 16s RNA gene using PCR method. Visualization of 16 s RNA amplicon genes with automatic electrophoresis capiler Qiaxel, Qiagen. Sequencing was carried out using Singapore's First BASE Sequencing service. The results showed that IL2 isolates and IL3 isolates could live up to 700C. Alignment analysis results using NCAST BLBI IL2 isolates showed 99% similarity with Bacillus thuringiensis strain H2682 (accession number CP009720.1). While isolate of IL3 thermophilic bacteria showed 94% similarity with Bacillus licheniformis strain 14DA11 (accession number CP023168.1). The results of phylogeny reconstruction with neighbor joining method, gene sequence 16S rRNA isolate IL2 showed the closest relation with Bacillus thuringiensis strain HD1011 (accession number CP009335.1). While IL3 isolate showed the closest relation with Bacillus licheniformis strain 14DA11 (accession number CP023168.1).
Perspectives of Using Alternative Binders in the Preparation of Composites with Natural Filler
Authors: Terpakova Eva , Števulová Nadežda
Published: August 2019

This paper reports on the possibility of using natural renewable materials as hemp fibers in the preparation of composites. The design and preparation of durable composites also requires the selection of suitable alternative binders, in order to reduce the production of carbon dioxide in the production of cement. The paper will present the results of composites with partial replacement of cement with natural clay, which was used in the traditional building in the past as classical binder. Experimental verification of mechanical, thermal and humidity parameters of composites was performed. The results confirmed some prospects for the use of experimental composites in terms of the compressive strengths values obtained after 28 days of maturing. Highest compressive strengths were measured for a reference set with 100% cement content and of course composites with increasing percentage cement replacement exhibited lower strengths. The results showed that replacing cement with natural clay does not create a new stronger material, but there is some potential for its use in the form of non-load-bearing elements. Experimental composites exhibited a relatively lower density compared to normal concrete, but the thermal conductivity values indicate the potential for their use as insulating materials.
Effect of Thermal Loading on Selected Parameters of Reinforced Concrete Obtained by Acoustic NDT Method
Authors: Plšková Iveta , Matysík Michal , Chobola Zdeněk
Published: August 2019

The paper presents the results of experiments carried out on test samples made from reinforced concrete. Within this experiment, concrete beams with steel reinforcement in the middle were made. The concrete samples were tested by a non-destructive acoustic Impact-echo method before and after high temperature loading (after cooling to room temperature). We focused on the dominant frequencies shift in the frequency spectra obtained by this method. The aim was to assess the ability of aforementioned acoustic method to detect the thermal damage of steel reinforced concrete.
Enhanced Electrical Properties of Fly Ash Geopolymer Composites with Carbon Nanotubes
Authors: Mizerová Cecílie , Kusák Ivo , Rovnaník Pavel , Bayer Patrik
Published: August 2019

Carbon nanotubes (CNTs) are used for the application in concrete especially due to their excellent physical properties. In this study, CNTs were used as a conductive admixture to prepare composites with enhanced electrical properties that might be potentially used in smart concretes or structures. We assessed the changes in selected electrical properties of fly ash geopolymer mortars (conductivity, resistance, capacitance) depending on the concentration of CNTs that ranged from 0.05 to 0.20%. The most convenient CNTs concentration was discussed considering both the electrical and mechanical properties (compressive and flexural strength). Mercury intrusion porosimetry and scanning electron microscopy were used to observe the distribution of CNTs and porosity of the mortars.
The Hydrothermal Stability of Alkali-Activated Fly Ash/Slag Pastes by the Incorporation of Cement Kiln Dust
Authors: Kubátová Dana , Rybová Alexandra , Zezulová Anežka
Published: August 2019

This paper deals with hydrothermal stability of inorganic aluminosilicate polymers, which were prepared by mixing blast furnace slag, fly ash and cement kiln dust in ratio 4:2:1. Cement kiln dust was used as alkaline activator with 4M sodium hydroxide solution. Samples were cured under hydrothermal conditions up to 170 °C for 24h and changes in mechanical properties, phase composition and porosity were monitored. During the hydrothermal process, the formation of zeolite from cancrinite group was monitored. The effect of the change of composition on the thermal expansion/shrinkage was studied by thermal dilatometry. Autoclaved samples were subjected to significant irreversible shrinkage during heating to 900 °C.
Development of the HVFAC Modulus of Elasticity
Authors: Ťažký Martin , Osuská Lucia , Hela Rudolf
Published: August 2019

Concretes with high fly ash content are within a unified world nomenclature often referred to as HVFAC, resp. high volume fly ash concrete. These concretes are characterized by the percentage of fly ash as an active admixture relative to a cement dose of at least in a ratio of 1:1. The use of these concretes falls into the field of construction with the necessary reduction in the development of hydration heat. In the experiment, long-term monitoring of the development of important mechanical parameters, namely the static modulus of compressive elasticity and compressive strength, was performed. Both monitored parameters play a very important role in the design of buildings, for which construction is HVFAC often used. These parameters were monitored within the carried out research until the time of 360 days. The results of the experiment give an overview of the pozzolanic reaction progress over the in the long-term time horizon and its impact on the concrete parameters monitored. The results clearly show that even after 360 days the development of the strength parameters of these concretes is not stopped.
Evaluation of Microstructure, Phase Composition and Hardness of Alternative Abradable Ceramic Coating Systems Produced by Means of Atmospheric Plasma Spraying
Authors: Jech David , Remešová Michaela , Komarov Pavel , Tkachenko Serhii , Česánek Zdeněk , Schubert Jan , Houdková Šárka , Čelko Ladislav
Published: August 2019

Only a few types of commercially available high temperature ceramic abradable coatings are presented on the market and most of them consist of partially stabilized yttria zirconia with polymer porosity former agent and/or hBN solid lubricant. The basic demand placed on abradable coatings include balance between hardness and erosion resistance. The contribution focuses on the description of microstructure, phase composition and hardness of alternative atmospheric plasma sprayed ceramic abradable coatings deposited from four different experimental powder mixtures: (i) commercial yttria-zirconia + 5 wt. % of experimental BaF2/CaF2, (ii) commercial yttria stabilized zirconia + 10 wt. % of experimental BaF2/CaF2, (iii) R&D powder SrxTiOy and (iv) R&D powder SrxTiOy + 5 wt. % of polyester. The abradable coating systems were of ~ 150 μm thick CoNiCrAlY bond coat and of ~ 800-1000 μm thick ceramic top coat. The microstructure and phase composition of all atmospheric plasma sprayed coating systems were evaluated by the means of scanning electron microscopy and X-ray diffraction techniques. To estimate coatings basic parameters the Rockwell hardness HR15Y was measured.
Utilization of CaO for Improvement of Durability of Vacuum Insulating Panels (VIP)
Authors: Zach Jiří , Peterková Jitka , Novák Vítězslav
Published: August 2019

Vacuum insulation panels (VIP) currently belong to a group of so-called super-insulating materials. These are special products with an extremely low equivalent value of the thermal conductivity coefficient. Despite this fact, the use of VIP in the construction industry is rather problematic. The main issue is the relatively complicated VIP integration into building structures, as well as the limited VIP durability. The issue of durability is also one of the main topics of VIP development and research in this field. The paper describes the possibilities of using CaO to increase the durability of vacuum insulation panels.
The Effect of Nanosilica on the Early Strength of Alkali-Activated Portland Composite Cements
Authors: Kryvenko Pavlo V. , Sanytsky Myroslav , Kropyvnytska Tetiana
Published: August 2019

Significant reduction of carbon footprint of the construction industry is achieved through the use of composite Portland cements. However, substitution levels of additives in the composite cements are limited due to slow strength development arising from low reactivity of the pozzolana compared to clinker phases especially at the early age. The aim of the study was to evaluate effect of nanosilica on formation of strength properties and structure at the early age. The Portland composite cement containing clinker, granulated blast furnace slag, zeolite tuff as natural pozzolana and limestone with additives of nanosilica, Na2SO4 and polycarboxylate ether was investigated. The results obtained with the help of PSD, XRD, DTA, TG and SEM techniques showed that addition into the cement paste of the nanosilica particles with high surface reactivity improved the composite cement microstructure and leaching of calcium became significantly lower, because nanosilica particles react with calcium hydroxide with the formation of a denser C-S-H gel at the early age of hardening.
Alternative Design Options for Preparing Beta Gypsum-Based Gypsum Premix
Authors: Hájková Iveta , Gazdič Dominik
Published: August 2019

Up to now, questions related to the preparation of pure sulphate binders, ie anhydrite mortar, alpha gypsum and beta gypsum, have been monitored at laboratory and pilot plant level within the framework of the work carried out at BUT. However, beta gypsum cannot be considered a high-grade sulfate binder. Therefore, the subject of this article is the use of beta gypsum to develop a gypsum premix that can be classified as a mixed sulfate binder universally applicable to the preparation of dry mortar mixtures. [1,2]
Influence of Flax Oil Additive on Rheological Properties of Lime Mortar
Authors: Reiterman Pavel , Davidová Vendula , Keppert Martin
Published: August 2019

Lime based mortars rank to the oldest used building systems used by human civilization worldwide. These materials offer suitable properties for various applications; however its low resistance in moist environment is their significant weakness. Hence, they were modified by number of additives and admixtures. The flax oil was applied to historic mortars to achieve hydrophobization, additionally this additive has considerable influence on the properties of fresh mixture as well. This paper introduces an experimental study dealing with the influence of flax oil on the properties of fresh lime based mortars with various water-to-binder ratios. The results of rheology properties were accompanied by the determination of mechanical performance, basic shrinkage and bulk density of hardened mortars.
Possibilities of Using Hazardous Waste as Filler to Polymer Mortar
Authors: Žlebek Tomáš , Hodul Jakub , Mészárosová Lenka , Drochytka Rostislav
Published: August 2019

The aim of the research was to verify whether it is possible to use specific types of treated hazardous waste as a filler in special epoxy based polymer mortars. In particular, it was a neutralizing sludge (NS-HW) with a relatively high content of heavy metals and other hazardous substances. This alkaline sludge is formed as a by-product of galvanic plating of steel elements in the baths, which are subsequently thickened and neutralized with calcium hydroxide. During the experimental verification, it was determined what resulting mechanical properties can be achieved by using 40% of the treated neutralizing sludge as a filler. In order to compare the achieved properties, a reference filler in form of a silica flour was used in the same binding matrix, and the polymer mortar containing waste foam glass of approximately the same fraction. It was discovered that, at the same percent filling, the polymer mortar with neutralizing sludge (NS-HW) had a similar tensile strength similar and cohesion with the concrete substrate as the reference material with the silica flour. Furthermore, it has been shown that this filler lowering the environmental footprint does not affect the chemical resistance of the polymer mortar to aggressive liquid solutions. As part of the microstructure observing, the uniformity of the filler distribution in the hardened polymer mortar, the incorporation of sludge particles into the epoxy matrix, and the quality of the polymer mortar bonding to the concrete was monitored using a high resolution digital microscope.
Evaluation on Formation of Aluminosilicate Network in Ternary-Blended Geopolymer Using Infrared Spectroscopy
Authors: Nguyen Hoc Thang
Published: August 2019

This study used an optimized mixture of red mud (RM), rice husk ash (RHA), diatomaceous earth (DE), and water glass solution (WGS) with silica modulus of 2.5 to produce geopolymer-based material. The geopolymer product was tested engineering properties which are in good agreement of ASTM requirements for building materials. For microstructure, the geopolymer samples were characterized by using Fourier-transform infrared spectroscopy (FTIR) and focused on evaluation on formation of aluminosilicate network in the ternary-blended geopolymer. The results showed that tetra-silicates or acid silicic (Si (OH)4 or H4SiO4) dissolved and reacted with the iron oxide (Fe2O3) in RM and DE to form the oligomer precursors of sialate-O-Si-O-Al-O-, sialate-siloxo-O-Si-O-Al-O-Si-O-, sialate-disiloxo-O-Si-O-Al-O-Si-O-Si-O-, tetra-silicate [SiO4]4-, and tetra-aluminate [AlO4]4-. The formation of sodium alumino-silicate iron hydroxide polymeric network were easily detected by vibrational modes of –T–O–T– and –T–O–Na units (T refers to tetrahedral such as that of Si or Al) and of –OH and H–O–H. As well as, there were appearances of the membered ring or chain structural units of geopolymers.
The cAMP–Adenosine Feedback Loop Maintains the Suppressive Function of Regulatory T Cells
Authors: Su Wenru , Chen Xiaoqing , Zhu Wenjie , Yu Jianfeng , Li Weihua , Li Yingqi , Li Zhuang , Olsen Nancy , Liang Dan , Zheng Song Guo
Published: August 2019

Therapeutic manipulation of regulatory T cells (Tregs) has been regarded as a promising approach for the treatment of immune disorders. However, a better understanding of the immunomodulatory mechanisms of Tregs and new safe and effective methods to improve the therapeutic effects of Tregs are highly desired. In this study, we have identified the key roles of a cAMP–adenosine positive feedback loop in the immunomodulatory function of Tregs. Adult male C57BL/6J mice were used for an experimental autoimmune uveitis (EAU) model, Tregs, and uveitogenic T cells (UTs). In established EAU, induced Tregs (iTregs) administration alleviated the inflammatory response. In vitro, iTregs inhibited UTs proliferation and inflammatory cytokine production. Mechanistically, cAMP is partially responsible for iTreg-mediated inhibition on UTs. Importantly, intracellular cAMP regulates CD39 expression and CD39-dependent adenosine production in iTregs, and cAMP directly participates in iTreg-derived adenosine production by a CD39 signaling–independent extracellular cAMP–adenosine pathway. Moreover, extracellular adenosine increases the intracellular cAMP level in Tregs. More importantly, increasing the cAMP level in iTregs before transfer improves their therapeutic efficacy in established EAU. Notably, the cAMP–adenosine loop exists in both iTregs and naturally occurring Tregs. These findings provide new insights into the immunosuppressive mechanisms of Tregs and suggest a new strategy for improving the therapeutic efficacy of Tregs in established autoimmune disease.
TNF Receptor–Associated Factor 5 Limits Function of Plasmacytoid Dendritic Cells by Controlling IFN Regulatory Factor 5 Expression
Authors: Kobayashi Shuhei , Sakurai Tsuyoshi , So Takanori , Shiota Yuka , Asao Atsuko , Phung Hai The , Tanaka Riou , Kawabe Takeshi , Maruyama Takashi , Kanno Emi , Kawakami Kazuyoshi , Owada Yuji , Ishii Naoto
Published: August 2019

The physiological functions of TNF receptor–associated factor 5 (TRAF5) in the skin inflammation and wound healing process are not well characterized. We found that Traf5−/− mice exhibited an accelerated skin wound healing as compared with wild-type counterparts. The augmented wound closure in Traf5−/− mice was associated with a massive accumulation of plasmacytoid dendritic cells (pDCs) into skin wounds and an enhanced expression of genes related to wound repair at skin sites. In accordance with this result, adoptive transfer of Traf5−/− pDCs, but not wild-type pDCs, into the injured skin area in wild-type recipient mice significantly promoted skin wound healing. The expression of skin-tropic chemokine receptor CXCR3 was significantly upregulated in Traf5−/− pDCs, and treatment with a CXCR3 inhibitor cancelled the promoted wound healing in Traf5−/− mice, suggesting a pivotal role of CXCR3 in pDC-dependent wound healing. Traf5−/− pDCs displayed significantly higher expression of IFN regulatory factor 5 (IRF5), which correlated with greater induction of proinflammatory cytokine genes and CXCR3 protein after stimulation with TLR ligands. Consistently, transduction of exogeneous TRAF5 in Traf5−/− pDCs normalized the levels of abnormally elevated proinflammatory molecules, including IRF5 and CXCR3. Furthermore, knockdown of IRF5 also rescued the abnormal phenotypes of Traf5−/− pDCs. Therefore, the higher expression and induction of IRF5 in Traf5−/− pDCs causes proinflammatory and skin-tropic characteristics of the pDCs, which may accelerate skin wound healing responses. Collectively, our results uncover a novel role of TRAF5 in skin wound healing that is mediated by IRF5-dependent function of pDCs.
A systems approach to business strategy
Authors: Anderson William S.
Published: August 2019

No abstract available
Workstation design and postural stress part 2: A case study
Authors: Golding Anthony
Published: August 2019

An evaluation of the musculoskeletal problems associated with seated workstations was undertaken for employees of the Human Sciences Research Council. A sample of 37 workers was studied for 14 days to determine which symptoms were due to chronic disorders and which were linked to postural stress or constrained posture as a result of workstation and task design. Techniques used included two subjective comfort ratings, clinical examinations by physiotherapists, anthropometric and workstation measurement, and video recordings of subjects’ posture over time. Subjects were selected from four occupations characterised by different levels of constraint in their work posture; data-entry typists, typists, programmers and researchers.Examinations revealed that 68% of the presenting symptoms were not related to any known previous trauma or pathology. Of these problems 86% were reported to be occupationally aggravated or related. The findings confirmed the hypothesis that postural constraint is accompanied by an increased likelihood of developing chronic musculoskeletal disorders.* The concepts of postural stress and postural constraint and their relationship to the development of muscle strain are discussed in Part 1: Background to occupational syndromes.
A survey of research publications in the SA Journal of Physiotherapy 1984 — 1988
Authors: Mitchell Jeanette
Published: August 2019

Following a two-year survey of current research at the eight University Physiotherapy Departments in South Africa, the major articles published in the South African Journal of Physiotherapy over the last five years were reviewed to establish authorship, research methodology and subject matter covered. It was found that of the total of 81 papers published during this time, 25 (30,9%) were produced by University Physiotherapy Departments. The first authors of the remaining 56 papers were physiotherapists employed elsewhere (41,1%); doctors/dentists (25,0%); other members of the allied medical disciplines (10,7%), other professionals (12,5%), and authors with unspecified qualifications (10,7%). Of the 25 articles written by University Physiotherapy Department authors, there were more descriptive papers (72,0%) than experimental (16,0%) or clinical reports (12,0%) or surveys (0,0%), and there were more articles on education/administration (36,0%) than on any other topic. Of the 56 papers published by non-University authors, there were again more descriptive articles (76,8%) than experimental (12,5%) or clinical reports (1,8%) or surveys (8,9%). These findings suggest a need for more scientifically orientated research, such as clinical and experimental trials, and for the publication, in the South African Journal of Physiotherapy, of more of the research projects of the University Physiotherapy Departments.
CAMINHOS DA CENA PARA A EDUCAÇÃO INFANTIL
Authors: Janiaski Vale Flávia
Published: August 2019

O presente artigo consiste em apontamentos e reflexões que emergiram da parte prática da pesquisa de doutorado intitulada “Colocando um novo ponto em cada conto: possibilidades da inserção do teatro na educação infantil”. A pesquisa (que está em fase de finalização) tem como objetivo central inserir o teatro na Educação Infantil através da contação de história e o do brincar. A peça ‘A Tempestade’ de William Shakespeare foi empregada como fio condutor de uma experiência cênico narrativo, pensada através da ambientação cênica e sonora do espaço escolar, como uma possibilidade de forjar uma experiência sensório-motora e artística para crianças entre três e cinco anos de idade. Foram realizadas apresentações em cinco Centro de Educação Infantil na cidade de Dourados - MS. Com as apresentações foi possível perceber a necessidade desta atividade no ambiente escolar, principalmente nos anos iniciais. A educação e o teatro juntas transformam, e esta transformação pessoal e coletiva é importante para o desenvolvimento social, cognitivo, corporal e imaginativo da criança e do professor.
UM ESTUDO ACERCA DAS ALTERAÇÕES NO USO E NA COBERTURA DA TERRA NA BACIA HIDROGRÁFICA DO RIO NEGRO-RS-BRASIL ENTRE 1977 E 2016
Authors: Schafer Alexandro Gularte , Branco Vivian Teixeira Alves
Published: August 2019

Este artigo apresenta o resultado do mapeamento das mudanças no uso e cobertura da terra na bacia hidrográfica do Rio Negro, Rio Grande do Sul, Brasil, em um intervalo de 39 anos, entre 1977 e 2016. Para tanto, foram utilizadas imagens da série de satélites Landsat (de 1977, 1985, 1996, 2003 e 2016) e técnicas de Processamento Digital de Imagens (PDI) e de análise de dados geográficos utilizando Sistema de Informações Geográficas (SIG). O método utilizado para a classificação supervisionada das imagens de satélite foi o da Máxima Verossimilhança (MaxVer). Com base nos resultados do mapeamento, verificou-se que as classes de uso e cobertura da terra predominantes ao longo do período em estudo foram: área florestal, campestre e cultura temporária. Em um primeiro momento, as classes “campestre” e “cultura temporária” passaram a ocupar áreas anteriormente ocupadas pela classe “área florestal”. Grande parte das alterações se deu devido ao aumento do cultivo do arroz. Em um segundo momento, a classe “cultura temporária” passou a ocupar áreas anteriormente ocupadas pela classe “campestre”. Nesse segundo momento, que abrange os dias atuais, ocorreu e ainda ocorre o aumento do cultivo de soja na bacia hidrográfica do Rio Negro-RS.