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The use of natural clays for the removal of dyes from wastewater, an important part of environmental remediation, is desirable due, not least, to their low cost. Palygorskite (PAL), a rigid-structure clay, is a good candidate for use in the elimination of industrial effluents, based on its exceptional adsorptive properties. Recently, a new palygorskite deposit has been discovered in Cuba and its use in the adsorption of dyes has not yet been explored in detail. In the present study, the use of unmodified natural Cuban palygorskite as a host for dyes was evaluated. Congo red (CR) and methylene blue (MB) were the anionic and cationic dyes tested, respectively, because of their wide use and toxicity to the environment. Several physical-chemical parameters were studied in order to establish the best experimental conditions under which to achieve the greatest dye load per gram of clay. Natural mixtures with different percentages of montmorillonite were also tested to evaluate their effect on the adsorption of the dyes. The results indicated that at pH values of ~7–9 and an initial dye concentration of 0.1 mg mL–1, the process was efficient. X-ray diffraction (XRD) analysis proved the surface adsorption of both dyes on the clays. The main interactions involved in the clay-dye system were electrostatic forces and H-bonds. Adsorption of CR seemed to be controlled fundamentally by the palygorskite phase. Such results support the use of this natural clay as an efficient host for the removal of MB and CR from wastewater.
Quantitative expressions of the kinetics of digestion are needed to estimate more precisely the quantity and composition of nutrients digested from feeds and their subsequent efficiency of utilization by the animal (Mertens, 1993). Degradation kinetic parameters are estimated by fitting appropriate models to data resulting from the measurement of either the undigested residue or the fermentation end-products after exposure of the feed to digestion. Kinetic data can be collected using either in vitro or in situ procedures. The in situ porous synthetic fibre bag technique has been extensively used to describe the kinetics of feeds degradation in the rumen. Several in vitro gas production methods have been developed to assess fermentation kinetics. The aim of this work was to study the relationship between rumen degradation parameters of forages determined either by the in situ procedure or by the gas production technique and to evaluate the potential of gas production measurements to assess the extent of dry matter degradation in the rumen.
In the last few years there has been an increasing concern regarding the use of antibiotics in ruminant feeding and the potential for selection of antibiotic-resistant pathogen micro-organisms. Some authors (Martin and Streeter, 1995; Callaway and Martin, 1996) suggested that organic acids (aspartate, fumarate, malate) potentially provide an alternative to currently used antimicrobial compounds. Several in vitro studies (Martin and Streeter, 1995; Callaway and Martin, 1996) showed that incorporation of DL-malate into fermentations with both Selenomonas ruminantium HD4 and with mixed ruminal micro-organisms resulted in changes in final pH, methane and volatile fatty acids (VFA) that are analogous to ionophore effects. Nisbet and Martin (1993) hypothesized that malate acted as an electron sink for hydrogen. However, the mechanism of action is not well known. Malate is a key intermediate in the succinate-propionate pathway and therefore could stimulate propionate production. The objective of this study was to study the effects of DL-malate and propionate on the in vitro rumen fermentation of a 50:50 foragexoncentrate diet.
The study was carried out using the rumen simulation technique (RUSITEC) following the general incubation procedure described by Czerkawski and Breckenridge (1977). The complete unit consisted of eight vessels with an effective volume of 700 ml each. The vessels inocula (solid and liquid) were obtained from three ruminally fistulated ewes given a diet consisting of 700 g alfalfa hay and 300 g concentrate per kg dry matter (DM) (Table 1) and transferred to the RUSITEC system within 30 min of the 1st day of the experiment. The flow through the vessels was maintained by continuous infusion of artificial saliva at a rate of 533 ml/day. Each vessel received daily a nylon bag containing 7 g alfalfa hay, 7 g concentrate and 0·10 g vitaminsminerals mix. From the 1st day of incubation three vessels received daily 5·62 mmol DL-malate (disodium salt; Sigma-Aldrich Quimica, S.A., Spain), three vessels received 5·62 mmol of propionate (monosodium salt; Sigma-Aldrich Quimica, S.A., Spain) and two vessels received no addition (control). DL-malate and propionate were weighed into the nylon bags and carefully mixed with the food.
The present study was designed to describe the effects of early feed restriction of Merino lambs on feed efficiency during the fattening period by examining ruminal microbiota and fermentation parameters, gastrointestinal morphology, digestibility or liver proteome. In total, 24 male Merino lambs were randomly assigned to two experimental treatments (n=12 per treatment). Lambs of the first group (ad libitum (ADL)) were kept permanently with the dams, whereas the other 12 lambs (restricted (RES)) were milk restricted. When lambs reached a live BW (LBW) of 15 kg, all the animals were offered the same complete pelleted diet (35 g dry matter/kg LBW per day) until slaughter at a LBW of 27 kg. The RES lambs showed poorer feed efficiency during the fattening period when compared with the ADL group (feed to gain ratio, 3.69 v. 3.05, P<0.001). No differences were observed in ruminal microbiota, fermentation parameters or apparent digestibility. However, the proportion of the small intestine and the length of ileal villi were reduced in the RES lambs. In total, 26 spots/proteins were identified in the liver proteomic profile, with significant differences (P<0.05) between experimental treatments, suggesting a higher catabolism of proteins and a reduction in β-oxidation of fatty acids in RES lambs when compared with the ADL animals. In conclusion, early feed restriction of Merino lambs during the suckling period promotes long-term effects on the small intestine and the proteomic profile of the liver, which may influence the metabolic use of nutrients, thus negatively affecting feed efficiency during the fattening phase.
We have used the Canada-France-Hawaii Telescope on Mauna Kea to obtain two deep CCD exposures in the central region of the Coma cluster, and we have used the new images to detect globular clusters in the central giant galaxy NGC 4874. One exposure with a total integration time of 2 hours lies in the halo of the giant galaxy. A second (comparison) exposure of the same integration time was taken within the cluster core but well away from any other bright galaxy. Our analysis, which includes both photometry and image classification with the automated routines called FOCAS, extends to a limiting B magnitude of 26.25. Image classification is a necessary part of this study because at the faintest limiting magnitudes globular clusters are easily confused with the rich population of faint background galaxies. We have been particularly successful in sorting stellar objects from galaxies because the image quality on our images is quite good: FWHM ~ 0.6 arcsec. The data were taken with the fast autoguiding instrument called ISIS (Thompson and Ryerson 1984)
Advances in radiocarbon dating by accelerator mass spectrometry (AMS) have made it possible to date prehistoric cave paintings by sampling the pigment itself instead of relying on dates derived from miscellaneous prehistoric remains recovered in the vicinity of the paintings. The work at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE) concentrated on prehistoric charcoal cave paintings from southern France and northern Spain. In most caves, pigment samples were collected from several paintings, and in some instances the sample size allowed for multiple independent measurements on the same figure, so that the coherence of the calculated dates could be tested. Before being dated, each specimen was subjected to a thermal treatment preceded by an acid and basic treatment of intensity commensurate with the sample size.
Nine bison drawings from three caves in the Cantabrian region of Spain—two from Covaciella, three from Altamira, and four from El Castillo—were sampled and dated. The 27 dates fell between 13,000 and 14,500 BP, allowing us to attribute the drawings to the Magdalenian period. The 24 dates for 13 drawings in the Cosquer cave indicated two distinct periods of painting activity—one around 28,000 BP and the other around 19,000 BP. The Chauvet cave paintings turned out to be the oldest recorded to date, as five dates fell between 32,000 and 31,000 BP. After discussing the sample preparation protocol in more detail, we will discuss the ages obtained and compare them with other chronological data.
Recently, new views of the current status of δ Scuti stars have been developed by Rodríguez & Breger (2001) who carried out an excellent review, listing 8 pre-main-sequence (PMS) δ Scuti candidates and examined the possibility of the existence of PMS δ Scuti variable stars. Here we discuss the nature of 4 stars from their list: 2 said to be members of NGC 2264 and 2 of NGC 6823.
Thirty-two lambs (n = 8 per treatment) were fed a total mixed ration (TMR) formulated either with palm oil (CTRL; 34 g palm oil/kg TMR) or flaxseed (FS) (85 g FS/kg TMR) alone or enriched with quercetin (QCT, 34 g palm oil plus 2 g QCT/kg TMR; FS-QCT, 85 g FS plus 2 g QCT/kg TMR). The animals were slaughtered after being fed for at least 5 weeks with the experimental diets and samples of ruminal contents and ruminal liquid were collected for quantitative real-time polymerase chain reaction analyses of ruminal microbial species and fatty acid profile or in vitro fermentation, respectively. Results demonstrated that Butyrivibrio vaccenic acid (VA) and Butyrivibrio stearic acid (SA) producing bacteria copy numbers were decreased when FS was added to the diet of fattening lambs, which seemed to be in agreement with numerically (but not significantly) lower values for gas production, methane production and butyric acid during in vitro incubation. Ciliate protozoa were significantly enhanced by QCT, which was in accordance with numerically (but not significantly) higher values for in vitro methane production. Moreover, the modifications observed in ruminal microbial populations (Butyrivibrio and ciliate protozoa) when FS and QCT were included together (but not separately) in the diet of fattening lambs were probably related to a trend towards significantly higher values of rumenic acid (RA) in ruminal content. In conclusion, when FS and QCT were administered together in the diet of fattening lambs quantitative changes in the ruminal microbiota were observed, which might have promoted an increment of RA concentration in ruminal contents.
Structural brain magnetic resonance imaging (MRI) traits share part of their genetic variance with cognitive traits. Here, we use genetic association results from large meta-analytic studies of genome-wide association (GWA) for brain infarcts (BI), white matter hyperintensities, intracranial, hippocampal, and total brain volumes to estimate polygenic scores for these traits in three Scottish samples: Generation Scotland: Scottish Family Health Study (GS:SFHS), and the Lothian Birth Cohorts of 1936 (LBC1936) and 1921 (LBC1921). These five brain MRI trait polygenic scores were then used to: (1) predict corresponding MRI traits in the LBC1936 (numbers ranged 573 to 630 across traits), and (2) predict cognitive traits in all three cohorts (in 8,115–8,250 persons). In the LBC1936, all MRI phenotypic traits were correlated with at least one cognitive measure, and polygenic prediction of MRI traits was observed for intracranial volume. Meta-analysis of the correlations between MRI polygenic scores and cognitive traits revealed a significant negative correlation (maximal r = 0.08) between the HV polygenic score and measures of global cognitive ability collected in childhood and in old age in the Lothian Birth Cohorts. The lack of association to a related general cognitive measure when including the GS:SFHS points to either type 1 error or the importance of using prediction samples that closely match the demographics of the GWA samples from which prediction is based. Ideally, these analyses should be repeated in larger samples with data on both MRI and cognition, and using MRI GWA results from even larger meta-analysis studies.
Duplex stainless steels are commonly used for various applications owing to their superior corrosion resistance and/or strength. They have ferromagnetic behavior together with a good thermal conductivity and a lower thermal expansion as a result of higher ferrite content than austenitic steels. Their ferrite matrix suffers a decomposition process during aging in the temperature range 650-950° C producing precipitation of austenite, σ and χ, carbides and nitrides. These intermetallic phases are known to be deleterious for corrosion resistance and mechanical properties.
In this work the effect of aging time during isothermal treatment at 850°C and 900°C on the microstructure of SAF 2205 Duplex Stainless Steels welded plates has been investigated. The aim of this work is to determine the morphology of σ phase, and perform a quantitative analysis of the precipitation process.
Submerged Arc Welding is used for processing. It produces a high content of δ ferrite in the heat affected zone and low content of austenite in the weld. Microstructural examination shows that the σ phase precipitates at δ ferrite/γ interphases. Longer aging treatments give rise to an increase of volume fraction together with a coarser morphology.
Today, stainless steel is widely used in automotive industry due to its high impact resistance, corrosion resistance and light weight. This paper present the research carried out to study the differences between microstructure and mechanical properties of 409 and 308 stainless steel sheets, each joints by gas tungsten arc welding (GTAW). For each of weldments, detailed analysis was conducted on the chemical composition, microstructure characteristics and mechanical properties of base metal (BM), heat affected zone (HAZ) and fusion zone (FZ). Scanning electron microscopy (SEM) and optical microscopy were used to analyze microstructural changes and mechanical properties, including microhardness and tensile test. This study can be a practical guide in the selection of other materials in order to determine the important to use in structural automotive industry.
Duplex stainless steels (DSS) have good mechanical and corrosion resistance properties which allow their application in very aggressive environments. However, their aging at 600–1000 °C causes the precipitation of dangerous intermetallic phases, resulting in serious detrimental effects on their interesting properties. These secondary phases are structural discontinuities which act as preferential cracks initiation sites and their negative effect is especially highlighted on toughness. For these reasons, many standards related to the manufacturing of DSS require the microstructure of these steels "free from intermetallics". In this paper, the effect of isothermal heat treatments on the impact toughness in two Duplex steels (SAF 2205 and Zeron®100) has been investigated, in order to study the influence of different amount of secondary phases on the toughness response.
Background: Children with decompensated heart failure are at high risk for arrhythmias, and ventricular assist device placement is becoming a more common treatment strategy. The impact of ventricular assist devices on arrhythmias and how arrhythmias affect the clinical course of this population are not well described. Methods and results: A single-centre retrospective analysis of children receiving a ventricular assist device between 1998 and 2011 was performed. In all, 45 patients received 56 ventricular assist devices. The median age at initial placement was 13 years (interquartile range 6–15). The median duration of support was 10 days (range 2–260). The aetiology of heart failure included cardiomyopathy, transplant rejection, myocarditis, and congenital heart disease. In all, 32 patients (71%) had an arrhythmia; 19 patients (42%) had an arrhythmia before ventricular assist device and eight patients (18%) developed new arrhythmias on ventricular assist device. Ventricular tachycardia was most common (25/32, 78%). There was no correlation between arrhythmia and risk of death or transplantation (p=0.14). Of the 15 patients who weaned from ventricular assist device, post-ventricular assist device arrhythmias occurred in nine (60%), with five (33%) having their first arrhythmia after weaning. Patients with ventricular dysfunction after ventricular assist device were more likely to have arrhythmias (p<0.02). Conclusions: Arrhythmias, especially ventricular, are common in children requiring ventricular assist device. They frequently persist for those able to wean from ventricular assist device.
In this work, it was used a Johnson-Cook elastic-plastic model to represent the behavior in the friction welding process of 6063 aluminum. Temperature and strain rate dependent laws were used to determine the behavior of the material. The results determined that the amount of heat transferred into the material dictates the quality and the microstructure of the welding and the mechanical strength of the welded joint in an ideal process.
In order to increase the wettability and capillary forces of the filler metal between micro-cracking and micro-porous on the fracture surfaces of 304 stainless steels, methods of impregnation of Si and growth of Ni nanoparticles were used. These nanoparticles have a role inside the Transient Liquid Phase (TLP) and the substrate when using Brazing process. TLP can react with the nanoparticles previously deposited between micro-cracking and micro-porous and therefore promotes the nucleation and growth sites of phases and decreases the formation of eutectic structures. This method increases the effectiveness of metallic components reparation using Brazing process. Such effectiveness is indicated by an inspection of microstructural failure analysis, as a first stage, in the covered zone by the filler metal.
At present, the industrial sector requires the recovery of tool steel components subjected to severe wear which are built with steel HWS these have the same properties in all tribology directions and have great success in building tooling. In this paper, we recover the previously HWS steel machining with a fillet of 2mm caused by the metallurgical recovery of the component, applying the process of plasma transferred arc PTA which has very good fats dilution properties in comparison to other conventional processes currently applied for the recovery of tooling, such as GTAW, SMAW, SAW. The experiment was conducted with input D2 and M2 with one and two welding seams, making the assessment metallography, hardness and wear tests pin-on-disk. Finding a decrease in the hardness of the interface line, according to the evaluation of wear pin-on-disk, had a higher wear rate of the filler metal in the M2 D2.
We performed a search for ground level solar cosmic ray enhancements on the full five minute database of the Mexico City neutron monitor using wavelet filters and two different statistical tests. We present a detailed analysis of the time series of November 2, 1992, where we found a previously unreported increment matching the onset time of the impulsive phase of the Ground Level Enhancement No. 54, thus providing evidence of an effective detection of high energy solar cosmic rays. This technique may help to find still undiscovered GLE signals in the Worldwide Neutron Monitor Database, to refine GLE spectra and, probably, to find a relationship between the latter and the solar cycle.