Effect of nano and micro-silica on bond behaviour of steel and polypropylene fibres in high volume fly ash mortar

This paper presents the effects of nano silica (NS), micro silica (MS) and combined NS and MS on bond behaviour of steel and polypropylene (PP) fibres in high volume fly ash (HVFA) mortar. Three types of bend configuration of hook-end steel fibre commercially available are considered, while the PP fibre was crimped shape. Three different fly ash contents of 40%, 50% and 60% (by wt) as partial replacement of ordinary Portland cement (OPC) are considered in HVFA mortar, while a control mortar containing 100% OPC was also considered. The NS and the MS was added as 2% and 10% (by wt), respectively as partial replacement of OPC in HVFA mortar containing 40% fly ash. In the case of combined NS and MS, 2% NS and 10% MS was used as partial replacement of OPC in HVFA mortar. However, in the case of HVFA mortars containing 40% fly ash and different NS and MS, total OPC content of 60% was kept constant in all HVFA mixes containing NS, MS and NS + MS. This was considered to compare these mixes with HVFA mortar containing 40% fly ash. Results indicate that maximum pull-out force of both steel and PP fibres decreases with increase in fly ash contents in HVFA mortars at both 7 and 28 days.The addition of 2% NS and 10% MS showed almost similar improvement in the maximum pull-out force of steel and PP fibres at both ages in HVFA mortar containing 40% fly ash. The combined use of 2%NS + 10%MS also improved the maximum pull-out force and higher than 2% NS and 10% MS. The reduction in large capillary pores in HVFA mortars containing nano and micro silica observed in Mercury Intrusion Porosity test improved the bond of steel and PP fibres in those mortar due to formation of additional calcium silicate hydrate (C-S-H) gel is believed to be the reason behind this improvement. The maximum pull-out force also increased with increase in number of bends in the hook-end of steel fibre in all mortars in this study at both 7 and 28 days. Extra energy absorbed by the higher number of bends is the reason of such improvement in maximum pull-out force. However, in the case of absorbed energy mixed results are observed in the case of different number of bends in steel fibre ends. Good correlations also exist between the maximum pull-out forces of all three types of steel fibres with compressive strength of mortars showing strong influence on the bond behaviour

Nondestructive monitoring of ageing of Alkali resistant Glass fiber reinforced cement (GRC)

Glass fiber reinforced cement (GRC) is a composite material made of portland cement mortar and alkali resistant (AR) fibers. AR fibers are added to portland cement to give the material additional flexural strength and toughness. However, ageing deteriorates the fibers and as a result the improvement in the mechanical properties resulted from the fiber addition disappears as the structure becomes old. The aim of this paper is monitoring GRC ageing by nondestructive evaluation (NDE) techniques. Two different NDE techniques (1) nonlinear impact resonant acoustic spectroscopy analysis and (2) propagating ultrasonic guided waves are used for this purpose. Both techniques revealed a reduction of the nonlinear behavior in the GRC material with ageing. Specimens are then loaded to failure to obtain their strength and stiffness. Compared to the un-aged specimens, the aged specimens are found to exhibit more linear behavior, have more stiffness but less toughness. Finally, undisturbed fragments on the fracture surface from mechanical tests are inspected under the electron microscope, to understand the fundamental mechanisms that cause the change in the GRC behavior with ageing.The authors want to acknowledge the financial support of the Ministerio de Ciencia e Innovacion MICINN, Spain, and FEDER funding (Ondacem Project: BIA 2010-19933) and BES-2011-044624. Also thanks to PAID-02-11 Program from Universitat Politecnica de Valencia.Eiras Fernández, JN.; Kundu, T.; Bonilla Salvador, MM.; Paya Bernabeu, JJ. (2013). Nondestructive monitoring of ageing of Alkali resistant Glass fiber reinforced cement (GRC). Journal of Nondestructive Evaluation - NDT and E International. 32:300-314. https://doi.org/10.1007/s10921-013-0183-yS30031432Bentur, A., Fibre, M.S.: Reinforced Cementitious Composites, 2nd edn. Taylor and Francis, New York (2007)Purnell, P., Short, N.R., Page, C.L.: A static fatigue model for the durability of glass fibre reinforced cement. J. 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Differentiation of Bacillus pumilus and Bacillus safensis using MALDI-TOF-MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) despite being increasingly used as a method for microbial identification, still present limitations in which concerns the differentiation of closely related species. Bacillus pumillus and Bacillus safensis, are species of biotechnological and pharmaceutical significance, difficult to differentiate by conventional methodologies. In this study, using a well-characterized collection of B. pumillus and B. safensis isolates, we demonstrated the suitability of MALDI-TOF-MS combined with chemometrics to accurately and rapidly identify them. Moreover, characteristic species-specific ion masses were tentatively assigned, using UniProtKB/Swiss-Prot and UniProtKB/TrEMBL databases and primary literature. Delineation of B. pumilus (ions at m/z 5271 and 6122) and B. safensis (ions at m/z 5288, 5568 and 6413) species were supported by a congruent characteristic protein pattern. Moreover, using a chemometric approach, the score plot created by partial least square discriminant analysis (PLSDA) of mass spectra demonstrated the presence of two individualized clusters, each one enclosing isolates belonging to a species-specific spectral group. The generated pool of species-specific proteins comprised mostly ribosomal and SASPs proteins. Therefore, in B. pumilus the specific ion at m/z 5271 was associated with a small acid-soluble spore protein (SASP O) or with 50S protein L35, whereas in B. safensis specific ions at m/z 5288 and 5568 were associated with SASP J and P, respectively, and an ion at m/z 6413 with 50S protein L32. Thus, the resulting unique protein profile combined with chemometric analysis, proved to be valuable tools for B. pumilus and B. safensis discrimination, allowing their reliable, reproducible and rapid identification.Dr. Kasthuri Venkateswaran, Dr. Irene Ouoba, Dr. Joseph W. Kloepper, Dr. Cecilie From and Dr. Maria Morea are gratefully acknowledged for providing isolates FO-36bT, SAFN-027, SAFN-037, KL-052, 51-3C and 82-2C; Bs31; SE 49 (AP3) and SE 52 (AP7); FEL 55, UNG22 and MIL46, respectively. Raquel Branquinho was supported by a PhD fellowship (Ref. SFRH/BD/61410/2009) and Clara Sousa by a post-doctoral fellowship (Ref. SFRH/BPD/70548/2010), from FCT (Fundacao para a Ciencia e Tecnologia, Portugal). Hugo Osorio acknowledges the funding from QREN-FEDER through the Operational Program ON. 2 - O Novo Norte. IPATIMUP is an Associate Laboratory of the Portuguese Ministry of Science, Technology and Higher Education and is partially supported by the Portuguese Foundation for Science and Technology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competin

Brown Planthopper (N. lugens Stal) Feeding Behaviour on Rice Germplasm as an Indicator of Resistance

BACKGROUND: The brown planthopper (BPH) Nilaparvata lugens (Stal) is a serious pest of rice in Asia. Development of novel control strategies can be facilitated by comparison of BPH feeding behaviour on varieties exhibiting natural genetic variation, and then elucidation of the underlying mechanisms of resistance. METHODOLOGY/PRINCIPAL FINDINGS: BPH feeding behaviour was compared on 12 rice varieties over a 12 h period using the electrical penetration graph (EPG) and honeydew clocks. Seven feeding behaviours (waveforms) were identified and could be classified into two phases. The first phase involved patterns of sieve element location including non penetration (NP), pathway (N1+N2+N3), xylem (N5) [21] and two new feeding waveforms, derailed stylet mechanics (N6) and cell penetration (N7). The second feeding phase consisted of salivation into the sieve element (N4-a) and sieve element sap ingestion (N4-b). Production of honeydew drops correlated with N4-b waveform patterns providing independent confirmation of this feeding behaviour. CONCLUSIONS/SIGNIFICANCE: Overall variation in feeding behaviour was highly correlated with previously published field resistance or susceptibility of the different rice varieties: BPH produced lower numbers of honeydew drops and had a shorter period of phloem feeding on resistant rice varieties, but there was no significant difference in the time to the first salivation (N4-b). These qualitative differences in behaviour suggest that resistance is caused by differences in sustained phloem ingestion, not by phloem location. Cluster analysis of the feeding and honeydew data split the 12 rice varieties into three groups: susceptible, moderately resistant and highly resistant. The screening methods that we have described uncover novel aspects of the resistance mechanism (or mechanisms) of rice to BPH and will in combination with molecular approaches allow identification and development of new control strategies

Resposta à flexão e análise de tenacidade de argamassas reforçadas com fibra de Curauá

O desenvolvimento e comercialização de materiais compósitos produzidos a partir de fibras naturais são considerados extremamente importante, uma vez que essas fibras reduzirão a dependência dos materiais produzidos com recursos não renováveis. Dentre essas fibras naturais destaca-se a fibra do curauá, sua utilização na produção de compósitos melhora de forma notável as propriedades do conjunto fibra matriz, logo o presente artigo objetiva estudar as propriedades mecânicas de compósitos reforçados com fibra de curauá, em especial sua resistência à flexão e tenacidade. Para isso foram confeccionadas cinco famílias de argamassas, uma de referência sem utilização da fibra e as outras quatro reforçada com fibra variando o comprimento da fibra e sua fração volumétrica. Verificou-se que a fibra do curauá ao ser adicionada em matriz cimentícia melhora suas propriedades mecânicas comparada a um compósito não reforçado com fibra, sua deformação, resistência à flexão e tenacidade são melhoradas

Gain-of-function human STAT1 mutations impair IL-17 immunity and underlie chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis disease (CMCD) may be caused by autosomal dominant (AD) IL-17F deficiency or autosomal recessive (AR) IL-17RA deficiency. Here, using whole-exome sequencing, we identified heterozygous germline mutations in STAT1 in 47 patients from 20 kindreds with AD CMCD. Previously described heterozygous STAT1 mutant alleles are loss-of-function and cause AD predisposition to mycobacterial disease caused by impaired STAT1-dependent cellular responses to IFN-γ. Other loss-of-function STAT1 alleles cause AR predisposition to intracellular bacterial and viral diseases, caused by impaired STAT1-dependent responses to IFN-α/β, IFN-γ, IFN-λ, and IL-27. In contrast, the 12 AD CMCD-inducing STAT1 mutant alleles described here are gain-of-function and increase STAT1-dependent cellular responses to these cytokines, and to cytokines that predominantly activate STAT3, such as IL-6 and IL-21. All of these mutations affect the coiled-coil domain and impair the nuclear dephosphorylation of activated STAT1, accounting for their gain-of-function and dominance. Stronger cellular responses to the STAT1-dependent IL-17 inhibitors IFN-α/β, IFN-γ, and IL-27, and stronger STAT1 activation in response to the STAT3-dependent IL-17 inducers IL-6 and IL-21, hinder the development of T cells producing IL-17A, IL-17F, and IL-22. Gain-of-function STAT1 alleles therefore cause AD CMCD by impairing IL-17 immunity