Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants. © Published under licence by IOP Publishing Ltd

Nanotailoring Stereolithography Resins for Unique Applications using Carbon Nanotubes

Nanostructured materials and exploiting their properties in stereolithography (SL) may open new markets for unique rapidly manufactured functional devices. Controlled amounts of multiwalled carbon nanotubes (MWCNTs) were successfully dispersed in SL epoxy-based resins and complex three-dimensional (3D) parts were successfully fabricated by means of a multi-material SL setup. The effect of the nanosized filler was evaluated using mechanical testing. Small dispersions of MWCNTs resulted in significant effects on the physical properties of the polymerized resin. A MWCNT concentration of .05 wt% (w/v) in DSM Somos® WaterShed™ 11120 resin increased the ultimate tensile stress and fracture stress an average of 17% and 37%, respectively. Electron microscopy was used to examine the morphology of the nanocomposite and results showed affinity between the MWCNTs and SL resin and identified buckled nanotubes that illustrated strong interfacial bonding. These improved physical properties may provide opportunities for using nanocomposite SL resins in end-use applications. Varying types and concentrations of nanomaterials can be used to tailor existing SL resins for particular applications.Mechanical Engineerin

Hydrogymnastics training program on physical fitness in elderly women

Se evaluó un programa de entrenamiento de hidrogimnasia sobre las capacidades físicas en 26 adultas mayores (grupo experimental n=16, grupo control n=10), determinadas mediante el protocolo senior fitness test, la hidrogimnasia fue 5 veces por semana por 12 semanas, con ejercicios aeróbicos del 50%-60% de la FCmáx. Se utilizó ANOVA 2x2, indicando interacción significativa (p=0.052) entre grupos y mediciones en la prueba de resistencia a la fuerza en extremidades inferiores, la prueba de agilidad de 2.4 metros tuvo interacción significativa (p≤0.01) entre grupos y mediciones, las pruebas de capacidad aeróbica step test de 2 minutos (p=0.02) y caminar 6 minutos indicaron interacción significativa entre grupos y mediciones (p=0.50); Se infiere que la hidrogimnasia en las adultas mayores participantes es eficaz en la mejora de las capacidades físicas principalmente aeróbicas, de resistencia a la fuerza y agilidad de miembros inferioresThe aim of this study was to evaluate the effect of a hydrogymnastics training program on physical fitness in 26 elderly women (experimental group n=16, control group n=10). The physical fitness was determined by the senior fitness test protocol, the hydrogymnastics consisted in aerobic exercise at 50%-60% of maximum heart rate, 5 times a week in a period of 12 weeks. ANOVA 2x2 as statistical test was used, indicating statistically significant interaction (p=0.052) between groups and measurements on test strength endurance in the legs by squatting on chair in 30 s, agility test 2.4 meters was significant interaction (p≤0.01) between groups and measures, testing aerobic capacity test step 2 minutes (p=0.02) and six minutes walk indicated significant interaction between groups and measurements (p=0.50), the results shown that hydrogymnastics in the elderly women participants was effective improving endurance, strength and agility mainly in leg

Notes on the age determination, ovariole changes and gonotrophic cycle of Simulium ochraceum in Guatemala

金沢大学留学生センター室内および野外個体の解剖観察をもとに, S. ochraceumの羽化から吸血までの最短期間を2日, 吸血から産卵までを5日, 産卵後まもなく2回目の吸血をすると仮定すると, 吸血-産卵-吸血(gonotrophic cycle)の最短期間は5日と考えられた。調査4地点(1977年10月∿12月)の平均産卵経験率はS. ochraceum 48.7%, S. callidum 46.9%, S. metallicum 41.2%, S. mexicanum 38.9%であった。産卵経験率およびsac-like relic率は日変化を示し, 午後に高い傾向を示した。以上のことからS. ochraceumの日生存率は0.866と計算され, 羽化後1回目の吸血でO. volvulusのMf.を取り込んだとして, これが感染型に発育し, 伝播可能になる吸血後9日目の生存率は27.3%と推定された。 Of the S. ochraceum in Guatemala, the shortest duration from emergence to blood-feeding, from blood-feeding to oviposition (both at 22℃) and from oviposition to next blood-feeding (under the field condition) were presumed to be 2 days, 5 days and 0 day, respectively. One gonotrophic cycle of this species was to be 5 days in the shortest case. The average parous rate observed in the blackflies collected at four locations from October to December, 1977 were 48.7% for S. ochraceum, 41.2% for S. metallicum, 46.9% for S. callidum and 38.9% for S. mexicanum. The parous rate showed diurnal change, those of which captured in the afternoon being somewhat higher. The survival rate of S. ochraceum for 9 days after blood-feeding when this species become infective, was estimated at 27.3%

Duration of blood feeding of Simulium ochraceum in relation to intake of Onchocerca volvulus microfilariae

金沢大学留学生センターグアテマラにおけるオンコセルカ症の主要媒介種Simulium ochraceumのOnchocerca volvulus仔虫のとりこみに関して実験を行った。仔虫のとりこみは, ブユが体表にとまってから30秒で始まった。3∿4分後には65%のブユが吸血を完了し, とりこまれる仔虫数が最高に達した。それ以後は吸血時間がのびても, とりこみ量は増加しなかった。仔虫密度が皮膚10(mm)^2あたり55∿116匹の中程度に感染した人にあっては, とりこまれる仔虫の数は皮膚中の仔虫の密度と関連していた。しかし仔虫密度が1.8と非常に低い人の場合に, 異常に高い仔虫のとりこみが観察された。このことは, 皮膚中の仔虫密度が低い場合には, 仔虫がブユの吸血時に誘引あるいは何らかの刺激を受けることを示唆するものかもしれない。 Intake of microfilariae of Onchocerca volvulus by Simulium ochraceum, the main vector of onchocerciasis in Guatemala, was studied. The initiation of intake of microfilariae was around 30sec after landing. Thereafter, the number of microfilariae taken by flies increased as the feeding time increased. After 3 to 4min of landing, 69% of flies finished their blood meal, and the intake of microfilariae reached the highest. Thereafter, increase of feeding time did not increase the intake. With the volunteers of moderate density of microfilariae (55-116 Mf per 10(mm)^2), the number of microfilariae taken by the flies was correlated with the density of microfilariae in human skin. With a volunteer of very low density (1.8 Mf per 10(mm)^2), however, an extraordinarily high intake of microfilariae was observed. This suggested the possibility of the flies attracting or stimulating the microfilariae in the skin of low density carriers

Effect of ripening on physico-chemical properties and bioactive compounds in papaya pulp, skin and seeds

Byproducts generated by the food industry represent an alternative to obtain functional ingredients. Byproducts of tropical fruits, such as papaya skin and seeds, represent a source of bioactive compounds (BC), which could change during fruit ripening. Effect of ripening stage (RS) on BC content and antioxidant properties of edible pulp, skin and seeds of papaya cv. Maradol was determined. Papaya skin showed significantly higher ascorbic acid (~250 mg AAE/100 g) content than seeds (~20 mg/100 g), while pulp had the highest values (~600 mg/100 g). However, papaya skin presented higher total phenolic content (~560 mg GAE/100 g) and flavonoids (~1000 mg QE/100 g) than pulp and seeds. Also, papaya skin showed the highest values followed by pulp and seeds with TEAC, FRAP and DPPH. Papaya skin had higher carotenoids and α-tocopherol (~1500 µg/100 g and ~4000 µg/100 g, respectively) content than pulp and seeds. BC content in each byproduct varied in all RS. Therefore, among the papaya byproducts, skin represents a good source of BC with good antioxidant properties, which may be used to extract them for its incorporation in functional foods depending on RS

Design, calibration, and performance of the MINERvA detector

The MINERvA(6) experiment is designed to perform precision studies of neutrino-nucleus scattering using nu(mu) and (nu) over bar (mu) neutrinos incident at 1-20 GeV in the NuMI beam at Fermilab. This article presents a detailed description of the MINERvA detector and describes the ex situ and in situ techniques employed to characterize the detector and monitor its performance. The detector is composed of a finely segmented scintillator-based inner tracking region surrounded by electromagnetic and hadronic sampling calorimetry. The upstream portion of the detector includes planes of graphite, iron and lead interleaved between tracking planes to facilitate the study of nuclear effects in neutrino interactions. Observations concerning the detector response over sustained periods of running are reported. The detector design and methods of operation have relevance to future neutrino experiments in which segmented scintillator tracking is utilized. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/)

Halogen ligth thermogravimetric technique for determining the retained water in fine aggregates used for concrete mixing design

[EN] Measuring the rate of water retention of the aggregates used in mortars and concrete is required to achieve a good mix design. The water retention, specifically absorption, is used to keep constant the water/cement ratio. This paper focuses on the study of a new technique for measuring retained water in fine aggregates. In order to obtain results, the procedure described in the existing standards takes more than 24 h. Additionally, it involves high consumption of heat energy due to the use of drying ovens. Furthermore, the results obtained remain highly variable and therefore discussed by the scientific community.In this research, a novel technique based on a halogen moisture analyzer was implemented. The technique was assessed using an experiment design with a surface response model. The most important factors and levels were identified together with the interactions between them. Finally, the model was validated and the results obtained with this technique were compared with those obtained by conventional techniques in order to verify that they were equivalent.Arias Jaramillo, Y.; Paya Bernabeu, JJ.; Ochoa Botero, JC. (2015). Halogen ligth thermogravimetric technique for determining the retained water in fine aggregates used for concrete mixing design. Journal of Thermal Analysis and Calorimetry: an international forum for thermal studies. 123:127-134. doi:10.1007/s10973-015-4902-8S127134123Djerbi Tegguer A. Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach. Constr Build Mater. 2012;27:112–6.Kasemchaisiri R, Tangtermsirikul S. A method to determine water retainability of porous fine aggregate for design and quality control of fresh concrete. Constr Build Mater. 2007;21:1322–34.Gonilho Pereira C, Castro-Gomes J, Pereira de Oliveira L. Influence of natural coarse aggregate size, mineralogy and water content on the permeability of structural concrete. Constr Build Mater. 2009;23:602–8.Cortas R, Roiziére E, Staquet S, Hamami A, Delplancke-Ogletree M. Effect of the water saturation of aggregates on the shrinkage induced cracking risk of concrete at early age. Cem Concr Compos. 2014;50:1–9.Black R. The determination of specific gravity using Siphon-Can method. Cem Concr Aggreg. 1986;8:46–50.Saxer E. A direct method of determining absorption and specific gravity of aggregates. 1956;2.Hughes B, Famili H., Part 1—Absorption of concrete aggregates, Part 2—saturated air techniques for determining the absorption of aggregates. In: Absorptions of concrete aggregates. Birmingham University; 1971.Tam VWY, Gao XF, Tam CM, Chan CH. New approach in measuring water absorption of recycled aggregates. Constr Build Mater. 2008;22:364–9.Balcedowiak W. Phase analysis of high-calcium line by TG. J Therm Anal Calorim. 2000;60:70–7.Mendoza O, Tobón JI. An alternative thermal method for identification of pozzolanic activity in Ca(OH)2/pozzolan pastes. J Therm Anal Calorim. 2013;114:589–96.Kosmatka SH, Kerkhoff B, Panarese W, MacLeod NF, McGrath RJ, Design and control of concrete mixtures. 7rd ed. Cement association of Canada. 2002. pp. 88.Cárdenas JI, Restrepo C. Patrimonio geológico y patrimonio minero de la cuenca carbonífera del suroeste antioqueño, Colombia. Boletín de ciencias de la tierra. 2006;18:91–102 ISSN 0120-3630 .Klein NS, Aguado A, Tollares-Carbonari BM, Real LV. Prediction of the water absorption by aggregates over time: modelling through the use of value function and experimental validation. Constr Build Mater. 2014;69:213–20

MINERvA neutrino detector response measured with test beam data

The MINERvA collaboration operated a scaled-down replica of the solid scintillator tracking and sampling calorimeter regions of the MINERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This article reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons are obtained from these data. A measurement of the parameter in Birks' law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4%, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINERvA neutrino cross section measurement program.Comment: as accepted by NIM