Different fiber materials as reinforcement for geopolymer composite

For the last two centuries, Ordinary Portland Cement (OPC) is the most popular building material in the world due to its high mechanical properties, ease of handling and low cost. However, the concrete industry is known to leave an enormous environmental footprint. Therefore, the development of sustainable materials that could replace the OPC is essential. One of such recent developments is an aluminosilicate based material that can be activated in an alkaline medium to form a hardened sustainable product, known as ‘Geopolymer’. Geopolymers exhibit equal or better engineering properties as compared to conventional concrete with better environmental foot print. However, geopolymer\u27s main disadvantage, as concrete, is its brittleness and low tensile properties. One way to overcome this limitation is by addition of fibers, as they can control cracking by crack bridging, resulting in an increase of the tensile properties of the geopolymeric composite. The purpose of this research was to develop a high performance geopolymer composite by addition of short fibers. Three different types of fibers were added to the matrix with two different fiber contents (0.5% and 1%). The idea was to add fibers of significant difference in their chemical nature and tensile properties: PP and Carbon fibers which are both hydrophobic, but have significant differently tensile behavior, and PVA which is hydrophilic like the geopolymeric matrix, and has moderate tensile properties. Their influence on the geopolymer flexural behavior was examined. The microstructure of the composite at the fracture surface was also studied to better understand the role of the fibers. The results of this research showed that all fibers improved the ductility and toughness of the matrix. Geopolymeric composites with 1% carbon fibers showed the highest flexural strength, +216% compared to plain matrix, followed by the PVA fiber composites. Different failure modes were observed – fiber pull-out for the PP and carbon composites, and fiber rupture for the PVA fiber composite. This can be explained based on the different chemical nature of the fibers which produce a different matrix-fiber interface

Metakaolin based geopolymers as soil stabilizers

In many kinds of engineering constructions, wind-swept soils and soft weak soils are often stabilized and strengthened with ordinary Portland cement (OPC) and lime, to increase soil strength and durability. Furthermore, such soil stabilizing can also prevent erosion and dust generation. However, OPC is known to leave an enormous environmental footprint on planet Earth as its production processes are significant energy consumers with high CO2 emissions. Therefore, the development of a novel generation of cements with high durability and environmental sustainability is essential. One of these novel binders is the alkali-activated binder based on aluminosilicates materials as metakaolin or industrials by-products such as fly ash or slags, commonly referred to as geopolymer. It has been found that geopolymers can exhibit high compressive strength and higher chemical and thermal resistance than cement-based materials [1]. Therefore, due to their high strength, low cost, low energy consumption and CO2 emissions, geopolymers offers a promising alternative to OPC [2]. Geopolymers also exhibit excellent adhesion to aggregates [3], therefore it is reasonable to assume that they can serve as an effective soil stabilizer. Please click Additional Files below to see the full abstract

Development of one-part geopolymers based on industrial waste

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TNF-α protects from exacerbated myocarditis and cardiac death by suppressing expansion of activated heart-reactive CD4+ T cells

BACKGROUND AND AIMS Tumour necrosis factor α (TNF-α) represents a classical proinflammatory cytokine and its increased levels positively correlate with the severity of many cardiovascular diseases. Surprisingly, some heart failure patients receiving high doses of anti- TNF-α antibodies showed serious health worsening. This work aimed to examine the role of TNF-α signalling on the development and progression of myocarditis and heart-specific autoimmunity. METHODS AND RESULTS Mice with genetic deletion of TNF-α (Tnf+/- and Tnf-/-) and littermate controls (Tnf+/+) were used to study myocarditis in the inducible and the transgenic T cell receptor (TCR-M) models. Tnf+/- and Tnf-/- mice immunized with α-myosin heavy chain peptide (αMyHC) showed reduced myocarditis incidence but the susceptible animals developed extensive inflammation in the heart. In the TCR-M model, defective TNF-α production was associated with increased mortality at a young age due to cardiomyopathy and cardiac fibrosis. We could confirm that TNF-α as well as the secretome of antigen-activated heart-reactive effector CD4+ T (Teff) cells effectively activated the adhesive properties of cardiac microvascular endothelial cells (cMVECs). Our data suggested that TNF-α produced by endothelial in addition to Teff cells promoted leucocyte adhesion to activated cMVECs. Analysis of CD4+ T lymphocytes from both models of myocarditis showed a strongly increased fraction of Teff cells in hearts, spleens, and in the blood of Tnf+/- and Tnf-/- mice. Indeed, antigen-activated Tnf-/- Teff cells showed prolonged long-term survival and TNF-α cytokine-induced cell death of heart-reactive Teff. CONCLUSIONS TNF-α signalling promotes myocarditis development by activating cardiac endothelial cells. However, in the case of established disease, TNF-α protects from exacerbating cardiac inflammation by inducing activation-induced cell death of heart-reactive Teff. These data might explain the lack of success of standard anti-TNF-α therapy in heart failure patients and open perspectives for T cell-targeted approaches

Retention of Re in metakaolin based geopolymer in the presence of an organic reductant – an experimental study

The goal of this research was to examine the change in redox sensitive contaminant retention and leaching behavior from a model geopolymer system, during oxidation and carbonation, in the presence of an organic reductant. The behavior of redox sensitive elements under variable environmental conditions is specifically important for understanding the leaching of radionuclides retained in geopolymeric materials (e.g. Tc) that are soluble when oxidized and insoluble under reducing conditions. An alkali-activated metakaolin geopolymer with high silica/alumina ratio was selected as a model material. Rhenium was selected as the model redox sensitive element, which exhibits a large valence (-3 to +7) and solubility range. Rhenium was introduced in its most oxidized form (VII) as Re2S7. Ascorbic acid was used as a reducing agent during geopolymer casting due to its high solubility and homogeneous distribution within the matrix. Cylindrical monoliths were cured for 90 days under an inert atmosphere (N2) and then aged for 60 days under 98% N2 + 2% CO2 or CO2 deficient air, at a constant relative humidity (68%). The samples were then subjected to EPA 1313 pH dependent leaching test and EPA 1315 monolith leaching test. Leachates were analyzed using DOC and ICP techniques. XRD and SEM – EDS imaging and analyses were used to characterizes the solids Results show that Re has precipitated as ReS2 (IV) in the matrix. The pH dependent leaching test show that Re was released homogenously throughout most of the pH range (3-12). However, the retention of the material aged under CO2 deficient air was three times lower, indicating that the main effect on leaching from this material is of the oxidation process. The natural pH values were 11.3 and 12 for the material aged under 2% CO2 and for material aged under CO2 deficient air respectively, indicating minor carbonation in the former, however, no carbonate minerals were detected in the matrix. Monolith leaching results show that the geopolymers aged under CO2 deficient air have retained significantly less Re (0.24% leaching) relative to the sample aged under 2% CO2 (0.07wt % leaching). -log(diffusivity) values were in the order of 15 and 16 for CO2 deficient air and 2% CO2 respectively. There is a clear positive correlation between the amount of Re and DOC released from the samples, where their amounts are significantly larger for the samples aged under CO2 deficient air, indicating that the main Re-release mechanism from these samples is related to chelation to organic species under oxidizing conditions

The configuration of the training triad in the territories of training in Documentology: Relations among themselves and with the context of applicatio

Mediante un estudio de casos se propone describir los modos en los que se expresa la formación en el contexto de educación de la Documentología, particularmente en las formas que se comporta la tríada formativa en el contexto de educación, así como sus vínculos entre éste y el contexto de aplicación. De esta manera, se han descripto dos territorios formativos. El primero, el aula-clase, presenta una relación formador-sujeto en formación asimétrica y un objeto aproximado desde lo conceptual. El segundo, el aula-pericial, cambia la dinámica de la tríada, se vencen las asimetrías y el objeto se acerca mediante la práctica.Throw a case study it’s proposed to describe the ways in which the training is expressed in the context of education of Documentology, particularly in the manners that involves to the training triad in the context of education, as well as the bound between this and the context of application. In this way, two territories have been descripted. The first one, the lessonclassroom, presents a relation between the trainer and the trainee asymmetric and an object approached from the theory. The second one, the forensic-classroom, the asymmetries are been overcame, and the object is approached through the practice.Fil: Garay Broggi, José Luis. Universidad Nacional del Nordeste. Facultad de Humanidades. Instituto de Ciencias de la Educación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Bruquetas Correa, Emilia Gabriela. Universidad Nacional del Nordeste; ArgentinaFil: Bar, Aníbal Roque. Universidad Nacional del Nordeste. Facultad de Humanidades. Instituto de Ciencias de la Educación; Argentin

Identification of Thioredoxin Glutathione Reductase Inhibitors That Kill Cestode and Trematode Parasites

Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR) is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms) and trematoda (flukes), while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites

Screening for Active Small Molecules in Mitochondrial Complex I Deficient Patient's Fibroblasts, Reveals AICAR as the Most Beneficial Compound

Congenital deficiency of the mitochondrial respiratory chain complex I (CI) is a common defect of oxidative phosphorylation (OXPHOS). Despite major advances in the biochemical and molecular diagnostics and the deciphering of CI structure, function assembly and pathomechanism, there is currently no satisfactory cure for patients with mitochondrial complex I defects. Small molecules provide one feasible therapeutic option, however their use has not been systematically evaluated using a standardized experimental system. In order to evaluate potentially therapeutic compounds, we set up a relatively simple system measuring different parameters using only a small amount of patient's fibroblasts, in glucose free medium, where growth is highly OXPOS dependent. Ten different compounds were screened using fibroblasts derived from seven CI patients, harboring different mutations