bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymers in Concrete – The Shielding against Neutron Radiation
Authors: Piotrowski Tomasz , Tefelski Dariusz B. , Mazgaj Michał , Skubalski Janusz , Żak Andrzej , Sokołowska Joanna Julia
Published: November 2015

Concrete has been used as a shield against high-energy photons (gamma) and neutrons since the beginning of use of nuclear reaction in energy, medicine and research. State of knowledge in shielding concrete technology is that while in case of protection against gamma radiation an increase in density caused by change of aggregate type for heavy-weight one is usually an efficient solution, the protection against neutrons is more complex. It is due to the differences in interactions of neutrons with the matter, depending on their kinetic energy and cross-sections for different reactions of the component atoms of the cement paste and the aggregate. The paper presents the results of the project NGS-Concrete - New-Generation Shielding Concrete. The aim is to design the composition of concrete against ionizing radiation, achieved by the use of experiment based on multi-criteria optimization of materials supported by the Monte Carlo simulations. Better concrete is the one that absorbs more thermal neutrons and slows down more fast neutrons at the same time. In the paper both results of Monte Carlo simulations and experimental studies on ordinary and heavyweight concrete containing epoxy polymer additive are presented. Close values of thermal neutron attenuation coefficients proved good accordance between simulation and experiment. The final conclusion is that epoxy resin is an efficient additive for neutron shielding concretes improving its ability to protect mainly against low energy neutrons. In experimental measurement there has not been observed an improvement of fast neutron attenuation due to increase of hydrogen atom content introduced with epoxy.
Comparative Study on the Elastic Modulus of Polymer Concrete
Authors: Yeon Kyu Seok , Kim Kwan Kyu , Kim Chul Young , Yeon Jae Heum
Published: November 2015

Polymer concrete is used for a wide range of precast structural applications and repair works for existing infrastructures. For these applications, one of the key mechanical propertiesthatneed to be consideredis the elastic modulus. In this study, the relationship between elastic modulus and compressive strength of polymer concrete made with three different types of resin (i.e., unsaturated polyester resin, acrylic resin, and epoxy resin) is comprehensively investigated using data sets available from previous studies in order to develop a prediction equation for elastic modulus that can be generally applied to polymer concrete. Results showed that the equation developed under this study can be reasonably adopted for the predictions of polymer concrete's elastic modulus as a function of compressive strength because the prediction equation has a high goodness of fit asrepresented by a R2 value of 0.77
Determination of Polymer Type and Content in Concrete Materials by FTIR and TGA
Authors: Tokura Takako , Lim Joyce , Chua Ai Ming , Lee Wey Liang , Wong James
Published: November 2015

Polymers are commonly used in concrete materials. The type and concentration of polymer are important information for stakeholders, because they have a critical impact on the properties of concrete materials. Therefore, reliable and accurate information is highly desirable. To this end, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) are used to analyze polymer contents in construction materials.FTIR spectroscopy is a suitable technique to identify the polymer type using IR spectrum matching. Additionally, functional group information can be easily obtained from each peak. Attenuated Total Reflection (ATR) method can be used to measure extracted polymers from construction materials to obtain IR spectra, and match against the library database to identify the polymer materials. TGA is one of the common thermal analysis methods. It measures the weight loss or gain of sample due to chemical reactions such as vaporization, decomposition and oxidation as a function of temperature. In this paper, we will discuss development of reliable analytical methods with which mixtures of polymer, fine aggregate and cement with different percentages of polymer content were prepared and evaluated.
Merging Cement Concrete, Concrete-Polymer Composites and Inorganic Polymer Technologies for Sustainability in Construction and Restoration
Authors: Van Gemert Dionys , Cizer Özlem
Published: November 2015

The study of microstructure formation in polymer-cement concrete provides opportunities to exploit synergetic actions between cement and polymer, leading to performance improvement and to a wide range of new and innovative properties and applications. Polymers can reduce the impact of construction industry on environment, by decreasing the carbon footprint of cement production. Renovation and restoration, largely figuring in the concept of sustainable construction development, thank their growing share in construction activity to the input of polymers in repair materials and in rehabilitation procedures. The study of ancient binders and mortars reveals aspects of the origins of the observed long lasting durability of those ancient mortars.
Effects of HEMC Powder and PP Fiber on the Drying Shrinkage of Cement Mortar
Authors: Yang Xiao Jie , Wang Pei Ming , Ming Shou Wang , Liu Li Fang
Published: November 2015

Influences of polypropylene (PP) fiber and hydroxyethyl methyl cellulose (M) on the shrinkage rate of cement mortar and its potential mechanism were investigated. Results show that both the addition of trilobal PP fiber and M would reduce the shrinkage rate of cement mortar if well applied. With the increasing of PP content, the shrinkage rate firstly decreases and then increases, and reaches the lowest shrinkage degree with fiber content of 0.20% (volume fraction). While for cement mortar with M, the greater the dosage, the less drying shrinkage rate. An addition of 0.6% M contributes to a decrease of 23.8% for the 180-days drying shrinkage than the control. Additionally, a combination of both PP fibers and M can significantly reduce the drying shrinkage of mortar, resulting in a decrease of 40% for the shrinkage rate.
Curing of Polymer-Cement Concrete – Search for a Compromise
Authors: Łukowski Paweł , Woyciechowski Piotr , Adamczewski Grzegorz , Rudko Magdalena , Filipek Kamil
Published: November 2015

In this paper there are presented results of research carried out for establishing the most favourable scenario of curing of the Polymer-Cement Concrete (PCC). The general recommendations for PCC point to the need of alternating conditions of curing of PCC. Polymer-cement concrete should be first cured in the wet conditions for effective hydration of Portland cement and then in air-dry conditions for polymer setting. According to the literature, the often accepted curing regime of PCC covers 5 days of wet curing and then the air-dry curing until the time of testing. According to the European Standards, the wet period should last 3 days. However, the authors` experiences show that the aforementioned scenarios is not the optimum one. The studies presented in this paper are the part of the larger research program, which – according to the authors` intention – should lead to the establishing of the optimum curing regime for PCC. The tests were carried out using two types of polymer modifiers: two-component epoxy resin and water dispersion of polyacrylates, introduced into the cement concrete mix. The following properties were accepted as the criteria of evaluation of PCC curing effectiveness: compressive strength, tensile splitting strength, surface tensile strength (by pull-off method), wear resistance, water penetration under pressure. These properties were evaluated after 28 days of curing according to the various regimes. The tests showed that the extension of the wet curing period beyond 5 days was favourable for the technical properties of PCC. The establishing of the optimum time of wet curing, however, needs further research. Also, some conclusions were formulated about the usefulness of the various properties as the criteria of PCC curing efficiency evaluation.
Economic Aspect of Hybrid Fiber Reinforced Composite
Authors: Han Dong Yeop , Han Min Cheol , Yang Seong Hwan , Han Cheon Goo
Published: November 2015

The aim of this presentation is to recommend an economical technique for preparing fiber-reinforced mortar for blast resistant structures using polymer fibers. Fiber-reinforced concrete was developed to improve ductility by preventing micro-cracking. It is also used to strengthen blast resistant structures, and to prevent spalling under the fire conditions. Because of the better mechanical properties and bonding performance, metal fiber is mainly used for the blast resistant structure. However, because of the high cost of the fiber, the cost of the reinforced cementitious composite is higher than normal concrete. This is especially true for short steel fiber where its high cost has to be weighed against its outstanding performance. As a solution, a more economical substitute can be found in polymer fibers of nylon and polyvinyl alcohol fibers, which cut costs without a significant decrease in performance. In this study, for fiber-reinforced mortar, each fiber and combination of fibers incorporated made up 1% to the total volume of the mortar. For fresh state properties, although the mortar contained combined fibers, there was no significant decrease in flow and air content. As the polymer fibers were combined with steel fibers, approximately 35% of tensile strength and 12% of flexural strength decreased. However, from the strain-stress relationship, the fiber-reinforced mortar with combined fibers showed more favorable results than single steel fiber. The results of this study are expected to contribute on the economic approach of fiber-reinforced cementitious composites using combined fibers.
Application of Non-Destructive Methods for Quality Control of Concrete Repair Efficiency
Authors: Garbacz Andrzej
Published: November 2015

Adhesion in this system is one of the most important factors that affect the reliability and durability of repair. According to the many standards and guidelines, e.g. new European Standard EN 1504-10 and ACI Concrete Repair Manual, a pull-off test is recommended for assessment of a bond quality in repair systems. The use of pull-off test, due to its semi-destructive character, is restricted by owners and managers. Therefore, the elaboration of reliable nondestructive method for an adhesion mapping could provide a quite advantageous alternative. Repair system is difficult to test with NDT methods, because of the many factors influencing the stress wave propagation. In this paper the possibility of application of various NDT methods for quality control of repair efficiency, including estimation of the bond strength, is discussed.
Strengthening of Column Stump Using Glass Fiber Composite Strengthening System
Authors: Lu Jin Ping , Tan Kang Hai , Zheng David
Published: November 2015

The durability of concrete structures has long been a concern of many countries, especially in the island country of Singapore, where many structures are constructed along coastal areas. Currently, the durability of concrete under marine conditions can be enhanced by the addition of admixtures, and using high grade concrete. The FRP system has been proven to be one of the effective method to strengthen the concrete structure. The FRP system, which composed of the epoxy and glass fiber was evaluated according to various standard testing methods to get the basic technical information of the FRP system. Concrete columns of high aspect ratio with the size of 420mm x 115mm x 1500mm, 200mm x 200mm x 700mm and 200mm x 300mm x 700mm were wrapped with the FRP system with 3 horizontal wrapping and tested to verify the effectiveness of FPR wrapping. The theoretical calculation by computer model were also performed to estimate the strength gain for comparison with testing results. The results showed that the FRP wrapping for this type of columns can increase the ultimate strength by an average of 31.8%, with a minimum of 24.4% and a maximum of 37.5%.
Novel Geopolymers Incorporating Wollastonite and Recycled Mixed Plastics
Authors: Wong S.F. , Ting S.K. , Lin M. , Shamini M. , Tay B.K.
Published: November 2015

This paper reports a study on novel geopolymers, focusing on chemically bonded composites, by incorporating wollastonite and recycled mixed plastics. Magnesium oxide and monopotassium phosphate were used as binders; while the recycled mixed plastics consisted of high-density polyethylene and polystyrene at different volume ratios. The effects of molar ratio (magnesium-to-phosphorus ratio), wollastonite-to-binder ratio and recycled mixed plastics content were investigated. The performance of geopolymers was evaluated based on their setting time and water absorption, compressive and flexural strengths as well as thermal properties.
Analytical Model for Assessing Reinforced Beams
Authors: Andreolli Ivanilto , Bernardo L. de A. , Tocantins M.W. , Ruschel R.H.
Published: November 2015

This study presents an analytical model for assessing reinforced simply supported beams based on recommendations of the Brazilian Concrete Norm (NBR-6118) and a study published by the International Federation of Concrete (fib). Rectangular and “T” sections are only considered in this study. The beam’s deformation depicted the diagram of moment curvature in regard with the limits of materials deformation in the elastic state is also explored. The results obtained by both Norms were complement with each other, revealing great similarity. Furthermore, destructive tests of reinforced beams made in the laboratory were compared with those obtained by the analytical model, showing excellent performance of the proposed model. The objective of this publication is the presentation of the analytical model. Analysis of comparing the results between the analytical model and from field tests were presented in another publication that will be mentioned in this study.
Application of Wedge Splitting Test for Evaluation of the Bond Strength in Repair System Alumina Cement Concrete vs. PCC Mortar
Authors: Chmielewska Bogumiła , Adamczewski Grzegorz , Wang Ru , Yang Zheng Hong , Wang P.
Published: November 2015

There are several key factors, which are considered, when selecting methods and systems for concrete repair. Good bonding between repair material and concrete substrate is a crucial and simultaneously complex phenomenon. This paper shortly presents methods used for the bond strength evaluation with different ways of loading of bonded joints. A systems consisting of high performance concrete substrate and two types of repair materials are investigated. The main goal of the work is to compare a polymer-cement modified mortar (PCC) and a rapidly setting repair concrete (based on alumina cement). Technical characteristic of the materials as well as their bond strength to concrete substrate are presented. Surface of concrete substrate is prepared by using different roughening techniques commonly applicable on site. Bond strength is measured by standard pull-of test and by the wedge splitting test (WST). WST test adaptation for that purpose allows to extend the description of adhesion using fracture mechanics parameters such a work of adhesion and fracture energy
Tensile Properties of Polymer Repair Materials - Effect of Test Parameters
Authors: Kamil Z. , Andrzej G. , Sandra C. , Barroso A.J.
Published: November 2015

In this research, five types of polymer repair materials were selected for investigation of the influence of sample shape, deformation rate and test temperature on the mechanical properties determined with an uniaxial tensile test. The results showed the clear effect of measurement conditions on tensile strength, elongation and modulus of elasticity. The highest tensile strength and modulus of elasticity were exhibited by epoxy resin for the filling of concrete cracks, which achieved 1% elongation. The lowest coefficient of dispersion characterized the results of tensile test carried out using dumbbell samples at a deformation rate of 50 mm/min. The effect of temperature varied with the material type.
Efficient Repair of Crack in SFRC with Low-Viscosity Epoxy Adhesive
Authors: Šušteršič Jakob , Zajc Andrej , Korla Jure , Leskovar Iztok
Published: November 2015

Efficiency of crack repair in Steel Fiber Reinforced Concrete (SFRC) was estimated on the base of the results obtained by wedge split test (WST) method. The main part of the paper pointed at the discussion of laboratory investigations into the thermal compatibility of the selected repair system, where cracks in the SFRC were sealed with low-viscosity epoxy adhesive. The obtained results show that ultimate split strength decreases with increasing into the number of freeze-thaw cycles, similar as adhesion between used epoxy adhesive and concrete surface. Because of bridged fibers of cracks have been reactivated by sealing those cracks with epoxy adhesive, toughness or energy absorption are achieved. Therefore, resistance of repaired SFRC in this way should be expected during the application where it is.subjected to thermal cyclizing (freeze-thaw cyclizing), including wetting and drying.
Sprayed Polymer Concrete for the Rehabilitation of Sewage Systems
Authors: Schulte Holthausen Robert , Raupach Michael
Published: November 2015

Concrete sewage systems can be severely damaged when attacked by biogenic sulfide corrosion. While minor aggressive exposures can be accounted by using a high sulfate resistant cement, higher concentrations of acid (pH 3.5) require the sealing and protection of concrete surfaces. Throughout the decades, polymer concrete (PC) has been used in sewage systems due to its high acid resistance. However, it has been limited to newly constructed pipes and manholes as well as local repair.
In cooperation with Massenberg GmbH, the Institute of Building Materials Research of RWTH Aachen University developed a new way of applying PC for the rehabilitation of damaged concrete surfaces of sewage systems; by dry spraying an epoxy mortar on concrete, layers with an average thickness of 20 mm on vertical and overhead surfaces were successfully produced. The dry sprayed PC was examined for its overall performance such as strength, adhesion, thermal expansion, and wear. A special focus has been put on the diffusion properties and the durability in an acidic environment. Based on these positive laboratory results, a first practical application in a waste water structure is currently underway.
Development of Polymer Concrete with Non-Standardised Fillers for Innovative Building Materials
Authors: Osburg Andrea , Gypser Alexander , Ulrich Martin
Published: November 2015

The use of polymer concrete in building construction is a relatively new application. A building block system (Modular Assembly System: MAS-System) and the mobile fabrication technology for the reversible construction of buildings with regionally available aggregates, were developed in a project of applied research. The aspects of the successful material development are described, especially with regard to the characterisation of both the binders and the polymer concretes, considering strength and durability. The polymer concrete consists approximately of 90 % fillers, 10 % polymer binder and additives. The investigation of the binder-system included the determination of gel time and temperature development, shrinkage, wetting of formwork materials and immersion tests with marine water. The aim was an adaptation and optimisation of the binder system. The characterisation of mechanical properties of the polymer concrete was realised by determining its strength in a temperature range between - 40 °C and 60 °C. Compression tests on wall segments were also realised. Ageing is an important aspect of the durability of polymer bonded materials. Special tests were used for an accelerated ageing, including impacts of temperature change, cold rain water and natural radiation.
Manufacture of High-Performance Concrete Made with Powdered Polyester Resin Waste and Carboxylic-Ester Based Superplasticizer
Authors: Rodríguez A. , Campos Pablo Luis , Garabito J. , García Juan , Santamaría Isabel
Published: November 2015

A high-performance concrete design is presented that incorporates powdered polyester resin waste as a fine aggregate material in partial substitution of sand, with additions of both a superplasticizer based on carboxylic ethers and silica fume. The potential application of the powdered polyester resin and its properties as an aggregate are both analysed as well as the mechanical behaviour, in both the fresh and the hardened states, of the concrete. Both the flexural and the compressive strength of the concrete were shown to depend on the amount of waste used in substitution of the sand.
The results of the research show that the designed concrete reaches the resistances of a high performance concrete with values ​​above 50 MPa. On the other hand, the rest of its properties are equivalents, both in the fresh and hardened state, proportional to the amount of powdered polyester resin that is added. However, to achieve this, the use of superplasticizers additives and admixtures of silica fume is necessary.
Influences of Latex and Mixing Procedure on Mechanical Properties of Hardened Cement Paste(II)
Authors: Han D. , Chen W. , Zhong S.
Published: November 2015

In this study,influences of latex and mixing procedure on flexural strength, compressive strength, elastic modulus and apparent fracture energy of hardened cement paste mixed with polycarboxylate (PC) as superplasticizer were analyzed. The results show that, the apparent density of fresh latex modified cement paste (LMCP) and the compressive strength of the hardened LMCP were reduced 1%-8% and 0-28% respectively compared with the control, while the flexural strength and apparent fracture energy were increased 11%-70% and 22%-157% respectively. In generally, the mixing procedure had gentle effect on the mechanical properties of harden LMCP with the same mp/mc, while the different mp/mc and latex types had greater impact. The amounts of polymer adsorbed changed by mixing procedure and had significantly effect on the properties fresh LMCP while very little on the harden LMCP.
Restoration of Historic Concrete Structures with Modern Materials - A Case Study
Authors: Gypser Alexander , Flohr Alexander , Osburg Andrea
Published: November 2015

Today the requirements for concrete restoration are not only aspects of retrofitting or restoration of bearing capacity but increasingly aspects of preservation of historic structures, such as industrial monuments, civil engineering structures and buildings of the 60s. The Polymer modified self-compacting concrete (PSCC) is a suitable material to be applied in this field, as it not only has excellent mechanical properties (e.g. high bond strength, low Young's modulus) but it is also possible to imitate colours and textures similar to those of the original surfaces. PSCC is therefore an interesting alternative to well established materials, such as PCC, sprayable PCC (SPCC) and shotcrete.Presented in this paper are the results of the further development of PSCC for a particular scenario where due to limited accessibility, the application method and therefore the mix design had to be optimised. Characteristic fresh and hardened concrete properties were investigated and special attention was given to deviation of the fresh concrete with regard to variations in the amounts of source materials.It is shown that although PSCC is a high-performance material, dosage of its source materials, mixing and application of the material itself can be done with simple conventional building site equipment. At the same time a robust fresh concrete as well as excellent surface properties of the hardened concrete can be obtained. Purpose-made mix designs can be developed for various applications with excellent results in performance and appearance.
Performance of a Fly Ash Geopolymeric Mortar for Coating of Ordinary Portland Cement Concrete Exposed to Harsh Chemical Environments
Authors: Tahri Walid , Abdollahnejad Z. , Mendes Jorge , Pacheco-Torgal F. , de Aguiar José Barroso
Published: November 2015

Premature degradation of ordinary Portland cement (OPC) concrete infrastructures is a current and serious problem with overwhelming costs amounting to several trillion dollars. The use of concrete surface treatments with waterproofing materials to prevent the access of aggressive substances is an important way of enhancing concrete durability. The most common surface treatments use polymeric resins based on epoxy, silicone (siloxane), acrylics, polyurethanes or polymethacrylate. However, epoxy resins have low resistance to ultraviolet radiation while polyurethanes are sensitive to high alkalinity environments. Geopolymers constitute a group of materials with high resistance to chemical attack that could also be used for coating of concrete infrastructures exposed to harsh chemical environments.This article presents results of an experimental investigation on the resistance to chemical attack (by sulfuric and nitric acid) of several materials: OPC concrete, high performance concrete (HPC), epoxy resin, acrylic painting and a fly ash based geopolymeric mortar. Two types of acids, each with high concentrations of 10%, 20% and 30%, were used to simulate long term degradation by chemical attack. The results show that the epoxy resin had the best resistance to chemical attack, irrespective of the acid type and acid concentration.
FRP Strengthening of Discontinuous Members
Authors: Tan Kiang Hwee
Published: November 2015

Deep beams, corbels, stepped beams, beams with openings and the like are structural members comprising discontinuous regions for which conventional flexural theory does not apply. To strengthen such members using fibre-reinforced polymer (FRP) systems, a rational approach based on strut-and-tie models (STMs) is desirable. This involves the strengthening of struts, ties and nodal zones where required. This study was carried out to illustrate the use of strut-and-tie models in FRP strengthening of reinforced concrete T-beams with a large opening created through the web. Five 3-meter long simply-supported beams were fabricated to simulate existing beams with webs punctured by openings of lengths varying from 180 to 720 mm and located at about 0.5 to 1.5 m from the near support. The depth of the opening was kept constant at 180 mm. Based on strut-and-tie modelling, the beams were strengthened using glass FRP sheets to carry the same ultimate load as a solid beam which had the same dimensions and internal steel reinforcement but without opening, that is, 200 kN. The beams were each subjected to a single load at one-third span from the other support. Test results indicated that all beams with strengthened opening performed as well as the solid beam without opening in terms of cracking and deflection characteristics, in addition to ultimate strength and ductility.
The Effect of Polymer Emulsion Addition on the Setting Time, Crack Formation and Strength of Cementitious Patch Repair Mortars
Authors: Kruger Deon , Herbst Neil , Bester Jannes
Published: November 2015

With millions of square meters of ageing exposed concrete surfaces throughout the world, concrete patch repair is becoming a major component of the civil construction industry. To ensure effective and efficient repairs and rehabilitation of deteriorating concrete surfaces, patch materials with excellent workability during the repair phase and durability during its design life cycle are required. The addition of polymer emulsions to cementitious repair mortars increase the setting time, crack resistance while negatively affects the strength properties of the mortar. Polymer emulsions include natural rubber, polyacrylonitrile and polivinylacetate, to name just a few [1]. This paper focus on the effect of adding different polymer emulsions at varying dosages to cementitious repair mortars to obtain a better understanding of the influences on setting times, crack formation properties and curing regime requirements for optimal strength development. Ambient temperature and relative humidity were kept constant during the testing cycles. The results obtained indicated that the introduction of a polymer emulsion tend to reduce both the initial and final setting times of the repair mortars but that is extends the duration between initial and final set when compared to unmodified repair mortars. Compressive strength reductions were observed when adding polymer emulsions to the repair mortar but it was clear that crack formation was eliminated with the addition of the emulsions
Impaired SNX9 Expression in Immune Cells during Chronic Inflammation: Prognostic and Diagnostic Implications
Authors: Ish-Shalom Eliran , Meirow Yaron , Sade-Feldman Moshe , Kanterman Julia , Wang Lynn , Mizrahi Olga , Klieger Yair , Baniyash Michal
Published: November 2015

Chronic inflammation is associated with immunosuppression and downregulated expression of the TCR CD247. In searching for new biomarkers that could validate the impaired host immune status under chronic inflammatory conditions, we discovered that sorting nexin 9 (SNX9), a protein that participates in early stages of clathrin-mediated endocytosis, is downregulated as well under such conditions. SNX9 expression was affected earlier than CD247 by the generated harmful environment, suggesting that it is a potential marker sensing the generated immunosuppressive condition. We found that myeloid-derived suppressor cells, which are elevated in the course of chronic inflammation, are responsible for the observed SNX9 reduced expression. Moreover, SNX9 downregulation is reversible, as its expression levels return to normal and immune functions are restored when the inflammatory response and/or myeloid-derived suppressor cells are neutralized. SNX9 downregulation was detected in numerous mouse models for pathologies characterized by chronic inflammation such as chronic infection (Leishmania donovani), cancer (melanoma and colorectal carcinoma), and an autoimmune disease (rheumatoid arthritis). Interestingly, reduced levels of SNX9 were also observed in blood samples from colorectal cancer patients, emphasizing the feasibility of its use as a diagnostic and prognostic biomarker sensing the host’s immune status and inflammatory stage. Our new discovery of SNX9 as being regulated by chronic inflammation and its association with immunosuppression, in addition to the CD247 regulation under such conditions, show the global impact of chronic inflammation and the generated immune environment on different cellular pathways in a diverse spectrum of diseases.
The DNA Ligase IV Syndrome R278H Mutation Impairs B Lymphopoiesis via Error-Prone Nonhomologous End-Joining
Authors: Park Jihye , Welner Robert S. , Chan Mei-Yee , Troppito Logan , Staber Philipp B. , Tenen Daniel G. , Yan Catherine T.
Published: November 2015

Hypomorphic mutations in the nonhomologous end-joining (NHEJ) DNA repair protein DNA ligase IV (LIG4) lead to immunodeficiency with varying severity. In this study, using a murine knock-in model, we investigated the mechanisms underlying abnormalities in class switch recombination (CSR) associated with the human homozygous Lig4 R278H mutation. Previously, we found that despite the near absence of Lig4 end-ligation activity and severely reduced mature B cell numbers, Lig4R278H/R278H (Lig4R/R) mice exhibit only a partial CSR block, producing near normal IgG1 and IgE but substantially reduced IgG3, IgG2b, and IgA serum levels. In this study, to address the cause of these abnormalities, we assayed CSR in Lig4R/R B cells generated via preassembled IgH and IgK V region exons (HL). This revealed that Lig4R278H protein levels while intact exhibited a higher turnover rate during activation of switching to IgG3 and IgG2b, as well as delays in CSR kinetics associated with defective proliferation during activation of switching to IgG1 and IgE. Activated Lig4R/RHL B cells consistently accumulated high frequencies of activation-induced cytidine deaminase–dependent IgH locus chromosomal breaks and translocations and were more prone to apoptosis, effects that appeared to be p53-independent, as p53 deficiency did not markedly influence these events. Importantly, NHEJ instead of alternative end-joining (A-EJ) was revealed as the predominant mechanism catalyzing robust CSR. Defective CSR was linked to failed NHEJ and residual A-EJ access to unrepaired double-strand breaks. These data firmly demonstrate that Lig4R278H activity renders NHEJ to be more error-prone, and they predict increased error-prone NHEJ activity and A-EJ suppression as the cause of the defective B lymphopoiesis in Lig4 patients.
Calpains Released by T Lymphocytes Cleave TLR2 To Control IL-17 Expression
Authors: Perez Joëlle , Dansou Boris , Hervé Roxane , Levi Charlène , Tamouza Houda , Vandermeersch Sophie , Demey-Thomas Emmanuelle , Haymann Jean-Philippe , Zafrani Lara , Klatzmann David , Boissier Marie-Christophe , Letavernier Emmanuel , Baud Laurent
Published: November 2015

Calpains are intracellular proteases that play a key role in inflammation/immunity. Rare studies show that they are partially externalized. However, the mechanism of this secretion and the functions of exteriorized calpains remain poorly understood. In this study, we found that mouse and human lymphocytes secreted calpains through an ABCA1-driven process. In turn, extracellular calpains inhibited IL-17A expression. We were able to attribute this function to a cleavage of the TLR2 extracellular domain, which prevented TLR2-induced transcription of molecules essential for IL-17A induction. Calpain exteriorization and TLR2 cleavage were critical for the control of IL-17A expression by low doses of IL-2. By using newly developed transgenic mice in which extracellular calpains are specifically inactivated, we provide evidence for the relevance of calpain externalization in vivo in regulating IL-17A expression and function in experimental sterile peritonitis and autoimmune arthritis, respectively. Thus, this study identifies calpain exteriorization as a potential target for immune modulation.
Serum Lipoproteins Are Critical for Pulmonary Innate Defense against Staphylococcus aureus Quorum Sensing
Authors: Manifold-Wheeler Brett C. , Elmore Bradley O. , Triplett Kathleen D. , Castleman Moriah J. , Otto Michael , Hall Pamela R.
Published: November 2015

Hyperlipidemia has been extensively studied in the context of atherosclerosis, whereas the potential health consequences of the opposite extreme, hypolipidemia, remain largely uninvestigated. Circulating lipoproteins are essential carriers of insoluble lipid molecules and are increasingly recognized as innate immune effectors. Importantly, severe hypolipidemia, which may occur with trauma or critical illness, is clinically associated with bacterial pneumonia. To test the hypothesis that circulating lipoproteins are essential for optimal host innate defense in the lung, we used lipoprotein-deficient mice and a mouse model of Staphylococcus aureus pneumonia in which invasive infection requires virulence factor expression controlled by the accessory gene regulator (agr) operon. Activation of agr and subsequent virulence factor expression is inhibited by apolipoprotein B, the structural protein of low-density lipoprotein, which binds and sequesters the secreted agr-signaling peptide (AIP). In this article, we report that lipoprotein deficiency impairs early pulmonary innate defense against S. aureus quorum-sensing–dependent pathogenesis. Specifically, apolipoprotein B levels in the lung early postinfection are significantly reduced with lipoprotein deficiency, coinciding with impaired host control of S. aureus agr-signaling and increased agr-dependent morbidity (weight loss) and inflammation. Given that lipoproteins also inhibit LTA- and LPS-mediated inflammation, these results suggest that hypolipidemia may broadly impact posttrauma pneumonia susceptibility to both Gram-positive and -negative pathogens. Together with previous reports demonstrating that hyperlipidemia also impairs lung innate defense, these results suggest that maintenance of normal serum lipoprotein levels is necessary for optimal host innate defense in the lung.
A CpG-Ficoll Nanoparticle Adjuvant for Anthrax Protective Antigen Enhances Immunogenicity and Provides Single-Immunization Protection against Inhaled Anthrax in Monkeys
Authors: Kachura Melissa A. , Hickle Colin , Kell Sariah A. , Sathe Atul , Calacsan Carlo , Kiwan Radwan , Hall Brian , Milley Robert , Ott Gary , Coffman Robert L. , Kanzler Holger , Campbell John D.
Published: November 2015

Nanoparticulate delivery systems for vaccine adjuvants, designed to enhance targeting of secondary lymphoid organs and activation of APCs, have shown substantial promise for enhanced immunopotentiation. We investigated the adjuvant activity of synthetic oligonucleotides containing CpG-rich motifs linked to the sucrose polymer Ficoll, forming soluble 50-nm particles (DV230-Ficoll), each containing >100 molecules of the TLR9 ligand, DV230. DV230-Ficoll was evaluated as an adjuvant for a candidate vaccine for anthrax using recombinant protective Ag (rPA) from Bacillus anthracis. A single immunization with rPA plus DV230-Ficoll induced 10-fold higher titers of toxin-neutralizing Abs in cynomolgus monkeys at 2 wk compared with animals immunized with equivalent amounts of monomeric DV230. Monkeys immunized either once or twice with rPA plus DV230-Ficoll were completely protected from challenge with 200 LD50 aerosolized anthrax spores. In mice, DV230-Ficoll was more potent than DV230 for the induction of innate immune responses at the injection site and draining lymph nodes. DV230-Ficoll was preferentially colocalized with rPA in key APC populations and induced greater maturation marker expression (CD69 and CD86) on these cells and stronger germinal center B and T cell responses, relative to DV230. DV230-Ficoll was also preferentially retained at the injection site and draining lymph nodes and produced fewer systemic inflammatory responses. These findings support the development of DV230-Ficoll as an adjuvant platform, particularly for vaccines such as for anthrax, for which rapid induction of protective immunity and memory with a single injection is very important.
Performances in extreme environments: effects of hyper/hypobarism and hypogravity on skeletal muscle
Authors: Bosco Gerardo , Verratti Vittore , Fanò Giorgio
Published: November 2015

Many environmental factors may affect muscle plasticity but some have exclusive characteristics that allow them to play a key role to maintain the muscle capacity to generate force; these factors are: i) the oxygen availability and ii) the load applied to muscle fibres. Hyperbarism is a condition that occurs when a man is subjected to pressure increases. To keep the lungs from collapsing, the air is supplied to him under high pressure which exposes the blood in the lungs to high alveolar gas pressures. Under this condition, the PO2 become sufficiently increased, serious disorders may occur, such as modification of oxygen delivery and/or oxygen availability to permit regular muscle contraction. Also altitude hypobaric hypoxia induces modification of muscle capacity to generate work. Prolonged exposure to high altitude leads significant loss in body mass, thigh muscle mass, muscle fiber area and volume density of muscle mitochondria. Spaceflight results in a number of adaptations to skeletal muscle, including atrophy and early muscle fatigue. Muscle atrophy is observed in a wide range of muscles, with the most extensive loss occurring in the legs, because astronauts are no longer needed to support the body's weight. This review will describe the background on these topics suggesting the strategies to correct the specific muscle changes in presence of environmental stresses, such as the alteration in oxygen-derived signaling pathways or the metabolic consequence of microgravity that may indicate rational interventions to maintain muscle mass and function.
Skeletal muscle ultrasound
Authors: Pillen Sigrid
Published: November 2015

Muscle ultrasound is a convenient technique to visualize normal and pathological muscle tissue as it is non-invasive and real-time. Neuromuscular disorders give rise to structural muscle changes that can be visualized with ultrasound: atrophy can be objectified by measuring muscle thickness, while infiltration of fat and fibrous tissue increase muscle echo intensity, i.e. the muscles become whiter on the ultrasound image. Muscle echo intensity need to be quantified to correct for age-related increase in echo intensity and differences between individual muscles. This can be done by gray scale analysis, a method that can be easily applied in daily clinical practice. Using this technique it is possible to detect neuromuscular disorders with predictive values of 90 percent. Only in young children and metabolic myopathies the sensitivity is lower. Ultrasound is a dynamic technique and therefore capable of visualizing normal and pathological muscle movements. Fasciculations can easily be differentiated from other muscle movements. Ultrasound appeared to be even more sensitive in detecting fasciculations compared to EMG and clinical observations, because it can visualize a large muscle area and deeper located muscles. With improving resolution and frame rate it has recently become clear that also smaller scale spontaneous muscle activity such as fibrillations can be detected by ultrasound. This opens the way to a broader use of muscle ultrasound in the diagnosis of peripheral nerve and muscle disorders.
Peripheral endocannabinoids regulate skeletal muscle development and maintenance
Authors: Zhao Dongjiao , Pond Amber , Watkins Bruce , Gerrard Dave , Wen Yefei , Kuang Shihuan , Hannon Kevin
Published: November 2015

As a principal tissue responsible for insulin-mediated glucose uptake, skeletal muscle is important for whole-body health. The role of peripheral endocannabinoids as regulators of skeletal muscle metabolism has recently gained a lot of interest, as endocannabinoid system disorders could cause peripheral insulin resistance. We investigated the role of the peripheral endocannabinoid system in skeletal muscle development and maintenance. Cultures of C2C12 cells, primary satellite cells and mouse skeletal muscle single fibers were used as model systems for our studies. We found an increase in cannabinoid receptor type 1 (CB1) mRNA and endocannabinoid synthetic enzyme mRNA skeletal muscle cells during differentiation. We also found that activation of CB1 inhibited myoblast differentiation, expanded the number of satellite cells, and stimulated the fast-muscle oxidative phenotype. Our findings contribute to understanding of the role of the endocannabinoid system in skeletal muscle metabolism and muscle oxygen consumption, and also help to explain the effects of the peripheral endocannabinoid system on whole-body energy balance.
Reduction and technical simplification of testing protocol for walking based on repeatability analyses: An Interreg IVa pilot study
Authors: Sarabon Nejc , Loefler Stefan , Fruhmann Hannah , Burggraf Samantha , Kern Helmut
Published: November 2015

The aim of this study was to define the most appropriate gait measurement protocols to be used in our future studies in the Mobility in Ageing project. A group of young healthy volunteers took part in the study. Each subject carried out a 10-metre walking test at five different speeds (preferred, very slow, very fast, slow, and fast). Each walking speed was repeated three times, making a total of 15 trials which were carried out in a random order. Each trial was simultaneously analysed by three observers using three different technical approaches: a stop watch, photo cells and electronic kinematic dress. In analysing the repeatability of the trials, the results showed that of the five self-selected walking speeds, three of them (preferred, very fast, and very slow) had a significantly higher repeatability of the average walking velocity, step length and cadence than the other two speeds. Additionally, the data showed that one of the three technical methods for gait assessment has better metric characteristics than the other two. In conclusion, based on repeatability, technical and organizational simplification, this study helped us to successfully define a simple and reliable walking test to be used in the main study of the project.
Serum biochemical activities and muscular soreness in transported goats administered with ascorbic acid during the hot-dry season
Authors: Minka Ndazo S , Ayo Olusegun J
Published: November 2015

The effects of handling, loading and 12 h of road transportation during the hot-dry season on muscular metabolism of 20 experimental goats administered orally with 100 mg/kg body weight of ascorbic acid (AA) dissolved in 10 ml of sterile water, and other 20 control goats given equivalent of sterile water 40 min prior to transportation were investigated. The result obtained post-transportation showed that handling, loading and transportation were stressful to the goats, especially the control goats and resulted into muscular damage and the development of delayed-onset-muscular-soreness (DOMS), which may lead to dark-firm-dry (DFD) syndrome meat with undesirable effects on its quality. In the experimental goats administered AA such transportation effects were minimal or completely abolished. The result demonstrated that AA reduced the incidence of DOMS and muscular damage in transported goats, therefore it may be used to improve the welfare and quality of meat obtained from goats subjected to long period of road transportation under adverse climatic conditions.
Selection of body sway parameters according to their sensitivity and repeatability
Authors: Sarabon Nejc , Kern Helmut , Loefler Stefan , Jernej Rosker
Published: November 2015

For the precise evaluation of body balance, static type of tests performed on a force plate are the most commonly used ones. In these tests, body sway characteristics are analyzed based on the model of inverted pendulum and looking at the center of pressure (COP) movement in time. Human body engages different strategies to compensate for balance perturbations. For this reason, there is a need to identify parameters which are sensitive to specific balance changes and which enable us to identify balance sub-components. The aim of our study was to investigate intra-visit repeatability and sensibility of the 40 different body sway parameters. Twenty-nine subjects participated in the study. They performed three different balancing tasks of different levels of difficulty, three repetitions each. The hip-width parallel stance and the single leg stance, both with open eyes, were used as ways to compare different balance intensities due to biomechanical changes. Additionally, deprivation of vision was used in the third balance task to study sensitivity to sensory system changes. As shown by intraclass correlation coefficient (ICC), repeatability of cumulative parameters such as COP, maximal amplitude and frequency showed excellent repeatability (ICC>0,85). Other parameters describing sub-dynamics through single repetition proved to have unsatisfying repeatability. Parameters most sensitive to increased intensity of balancing tasks were common COP, COP in medio-lateral and in antero-posterior direction, and maximal amplitues in the same directions. Frequency of oscilations has proved to be sensitive only to deprivation of vision. As shown in our study, cumulative parameters describing the path which the center of pressure makes proved to be the most repeatable and sensitive to detect different increases of balancing tasks enabling future use in balance studies and in clinical practice.