Role of soil-derived dissolved substances in arsenic transport and transformation in laboratory experiments

Dissolved substances derived from soil may interact with both soil surfaces and with arsenic and subsequently influence arsenic mobility and species transformation. The purpose of this study was to investigate arsenic transport and transformation in porous media with a specific focus on the impact of soil-derived dissolved substances, mainly consisting of inorganic colloids and dissolved organic matter (DOM), on these processes. Arsenic transport and transformation through columns, which were packed with uncoated sand (UC) or naturally coated sand (NC) and fed with arsenate (AsV) or monomethylarsonic acid (MMA) spiked influents, were investigated in the presence or absence of soil-derived dissolved substances. The presence of soil-derived inorganic colloids and/or DOM clearly enhanced As transport through the column, with the fraction of As leached out of column (referring to the total amount added) being increased from 23 to 46% (UC) and 21 to 50% (NC) in AsV experiments while 46 to 64% (UC) and 28 to 63% (NC) in MMA experiments. The association of arsenic with DOM and the competitive adsorption between arsenic and DOM could account for, at least partly, the enhanced As movement. Distinct species transformation of As during transport through soil columns was observed. When AsV was the initial species spiked in the influent solutions, only arsenite (AsIII) was detected in the effluents for UC columns; while both AsIII (dominant) and AsV were present for NC columns, with AsIII being the dominant species. When MMA was initially spiked in the influent solutions, all method detectable As species, AsIII, AsV, MMA, and dimethylarsenic acid (DMA) were present in the effluents for both soil columns. These results indicate that risk assessment associated with As contamination, particularly due to previous organoarsenical pesticide applications, should take into account the role of soil-derived dissolved substances in promoting As transport and As species transformation.     

A novel enzymatically-mediated drug delivery carrier for bone tissue engineering applications: combining biodegradable starch-based microparticles and differentiation agents

In many biomedical applications, the performance of biomaterials depends largely on their degradation behavior. For instance, in drug delivery applications, the polymeric carrier should degrade under physiological conditions slowly releasing the encapsulated drug. The aim of this work was, therefore, to develop an enzymatic-mediated degradation carrier system for the delivery of differentiation agents to be used in bone tissue engineering applications. For that, a polymeric blend of starch with polycaprolactone (SPCL) was used to produce a microparticle carrier for the controlled release of dexamethasone (DEX). In order to investigate the effect of enzymes on the degradation behavior of the developed system and release profile of the encapsulated osteogenic agent (DEX), the microparticles were incubated in phosphate buffer solution in the presence of α-amylase and/or lipase enzymes (at physiological concentrations), at 37°C for different periods of time. The degradation was followed by gravimetric measurements, scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy and the release of DEX was monitored by high performance liquid chromatography (HPLC). The developed microparticles were shown to be susceptible to enzymatic degradation, as observed by an increase in weight loss and porosity with degradation time when compared with control samples (incubation in buffer only). For longer degradation times, the diameter of the microparticles decreased significantly and a highly porous matrix was obtained. The in vitro release studies showed a sustained release pattern with 48% of the encapsulated drug being released for a period of 30 days. As the degradation proceeds, it is expected that the remaining encapsulated drug will be completely released as a consequence of an increasingly permeable matrix and faster diffusion of the drug. Cytocompatibility results indicated the possibility of the developed microparticles to be used as biomaterial due to their reduced cytotoxic effects.     

Improved design of tubular wind tower foundations using steel micropiles

The constant increase in the wind power production leads to the need of higher wind towers, which brings up some questions regarding the effectiveness of tubular towers and respective foundations. This work focuses on the comparative structural design, life cycle behaviour and costs of onshore concrete shallow foundations for tubular wind towers (WT) when steel micropiles are used to improve resistance of the soil–structure interface (hybrid foundation). Typical wind loading for Turbine Class II and moderate seismicity (.25 g peak ground acceleration) is used to design and analyse 18 WT foundation case studies. This allows the comparison between shallow and hybrid foundations designed for three different hub heights and respective turbine rated power (80 m/2 MW, 100 m/3.6 MW and 150 m/5 MW) and for three different tubular tower solutions (steel, concrete and hybrid steel–concrete). The possible benefits of the solution using steel grouted micropiles are discussed in terms of potential environmental and economic impacts using life cycle analysis. The use of micropiles reveals to be an interesting solution to improve common shallow WT foundations since it allows the reduction of the dimensions of the foundation leading to significant environmental and cost benefits.     

Enhanced complexity and catalytic efficiency in the hydrolysis of phosphate diesters by rationally designed helix-loop-helix motifs

HJ1, a 42-residue peptide that folds into a helix-loop-helix motif and dimerizes to form a four-helix bundle, successfully catalyzes the cleavage of "early stage" DNA model substrates in an aqueous solution at pH 7.0, with a rate enhancement in the hydrolysis of heptyl 4-nitrophenyl phosphate of over three orders of magnitude over that of the imidazole-catalyzed reaction, k(2)(HJ1)/k(2)(Im) = 3135. The second-order rate constant, k(2)(HJ1) was determined to be 1.58x10(-4) M(-1) s(-1). The catalyst successfully assembles residues that in a single elementary reaction step are capable of general-acid and general-base catalysis as well as transition state stabilization and proximity effects. The reactivity achieved with the HJ1 polypeptide, rationally designed to catalyze the hydrolysis of phosphodiesters, is based on two histidine residues flanked by four arginines and two adjacent tyrosine residues, all located on the surface of a helix-loop-helix motif. The introduction of Tyr residues close to the catalytic site improves efficiency, in the cleavage of activated aryl alkyl phosphates as well as less activated dialkyl phosphates. HJ1 is also effective in the cleavage of an RNA-mimic substrate, uridine-3'-2,2,2-trichloroethyl phosphate (leaving group pK(a) = 12.3) with a second-order rate constant of 8.23x10(-4) M(-1) s(-1) in aqueous solution at pH 7.0, some 500 times faster than the reaction catalyzed by imidazole, k(2)(HJ1)/k(2)(Im) = 496.     

Direct low-temperature synthesis of rutile nanostructures in ionic liquids

The direct synthesis of crystalline titania nanorods by sol-gel chemistry in a special ionic liquid is reported. Unexpectedly, the high-temperature modification, rutile, is obtained directly under ambient conditions. X-ray diffraction and high-resolution transmission electron microscopy measurements support the highly crystalline and structural quality of the sample. The phase-directing property of the ionic liquids is attributable to the imide group in the counter ion, which exhibits strong interaction with specific rutile faces. Lithium insertion experiments were performed and revealed high and reversible loading capacities of up to 200 mAh g(-1).     

Application of dissimilarity indices, principal coordinates analysis, and rank tests to peak tables in metabolomics of the gas chromatography/mass spectrometry of human sweat

The majority of works in metabolomics employ approaches based on principal components analysis (PCA) and partial least-squares, primarily to determine whether samples fall within large groups. However, analytical chemists rarely tackle the problem of individual fingerprinting, and in order to do this effectively, it is necessary to study a large number of small groups rather than a small number of large groups and different approaches are required, as described in this paper. Furthermore, many metabolomic studies on mammals and humans involve analyzing compounds (or peaks) that are present in only a certain portion of samples, and conventional approaches of PCA do not cope well with sparse matrices where there may be many 0s. There is, however, a large number of qualitative similarity measures available for this purpose that can be exploited via principal coordinates analysis (PCO). It can be shown that PCA scores are a specific case of PCO scores, using a quantitative similarity measure. A large-scale study of human sweat consisting of nearly 1000 gas chromatography/mass spectrometry analyses from the sweat of an isolated population of 200 individuals in Carinthia (Southern Austria) sampled once per fortnight over 10 weeks was employed in this study and grouped into families. The first step was to produce a peak table requiring peak detection, alignment, and integration. Peaks were reduced from 5080 to 373 that occurred in at least 1 individual over 4 out of 5 fortnights. Both qualitative (presence/absence) and quantitative (equivalent to PCA) similarity measures can be computed. PCO and the Kolomorogov-Smirnoff (KS) rank test are applied to these similarity matrices. It is shown that for this data set there is a reproducible individual fingerprint, which is best represented using the qualitative similarity measure as assessed both by the Hotelling t2 statistic as applied to PCO scores and the probabilities associated with the KS rank test.     

Immobilization of drugs for glaucoma treatment

Recently there have been some developments in the preparation of controlled drug delivery systems for glaucoma. Many materials are being used in this area, namely gelatine and chitosan. Both of them present high levels of biocompatibility and biodegradability. In this paper, we wish to report the work we have been doing on the preparation and characterization of hydrogels based on gelatine and chitosan. The crosslinking agents used were 1-(3-(Dimethylamino)propyl)-3-Ethylcarbodiimide hydrocholide (CDI), 1,4-Butanodiol diglycidyl ether (epoxyde 1), Ethylene glycol diglycidyl ether (epoxyde 2) and genipin. The results obtained showed that all of the films were hydrogels. The surface and transversal cut showed a porous surface in all the films. The thermal analysis proved the modifications in the polymeric chains, with the stabilization of all of them by the crosslinking agents. The release pattern indicates that the gelatine films were the best since they release the adequate proportion of drug. Finally, the cytotoxicity showed that the gelatine films were all biocompatible, specially the ones crosslinked with one of the Epoxydes.     

Acceptability and safety of novel infant porridges containing lyophilized meat powder and iron-fortified wheat flour

BACKGROUND: Lyophilized meat powder with iron-fortified wheat flour can be used to produce an infant porridge with bioavailable iron, but its acceptability and safety are unknown. OBJECTIVE: To evaluate the acceptability and safety of porridges containing lyophilized meat powder and iron-fortified wheat flour. METHODS: Peruvian mothers' input was used to develop porridges without (no meat) and with meat powder (low or high chicken liver, low or high chicken thigh). Acceptability was determined by maternal hedonic scoring, 9-day infant intake, and videotape analysis of how well infants liked each porridge. Dry and cooked porridges and meat ingredients were tested for microorganisms; meats were tested for pesticides. RESULTS: Mothers gave higher acceptability scores to the no-meat porridge, followed in order by low and high quantities of meat powder (e.g., mean +/- SD "taste"scores were 4.5 +/- 0.9 for the no-meat, 3.7 +/- 1.1 for the low-liver, and 3.3 +/- 1.1 for the high-liver porridges, p = .0001). Infants' porridge intake did not differ: 61.4 +/- 47.1 g of no-meat, 62.1 +/- 44.9 g of low-thigh, and 67.5 +/- 42.0 g of low-liver (p = .7), as supported by the video analysis. Microbiologic safety was acceptable except for marginally acceptable molds and yeasts in dry ingredients. No pesticide residues were detected. CONCLUSIONS: Despite mothers' clear preference for no-meat porridges, infants consumed equal amounts of porridges with and without meat. Thus, if mothers can be convinced to feed the meat-containing porridges to the infants despite their own preferences, the infants will consume these porridges. The mold and yeast content of the porridge ingredients must be reduced.     

Effect of visitors’ pressure on soil and vegetation in several different micro-environments in urban parks in Tel Aviv

The effect of the pressure imposed by visitors on urban soil and herbaceous vegetation was investigated in seven micro-environments in parks in Tel Aviv. Soil properties (organic matter content, soil moisture, soil surface compaction/penetration depth), litter biomass, and herbaceous vegetation characteristics (vegetation cover, number of species, height) were determined in seven micro-environments: oak and pine trees, each under high and under low visitors’ pressure; a herbaceous area without visitors’ pressure; paths; and a resting area. Soil samples were collected from the upper 0–5 cm soil depth. In addition, in the tree micro-environments soil samples were taken at 0.5, 1, 2, and 3 m from the tree trunk. Averages and variances of soil properties and the vegetation characteristics varied among the various micro-environments and according to visitors’ pressure. Soil organic matter and soil moisture contents were significantly higher under oak trees with low visitors’ pressure than in other micro-environments. Litter biomass and penetration depth significantly decreased with increasing visitors’ pressure under pine and, especially, oak. The vegetation cover, number of species, and height of herbaceous vegetation were greatest in the herbaceous area, lower under with the trees where there was high visitors’ pressure and lowest in paths and resting areas. Thus, the soil properties in the oak micro-environment and the vegetation characteristics in the herbaceous area were the most sensitive to visitors’ pressure. For each tree and open area, increasing visitors’ pressure was accompanied by increasing spatial homogeneity of soil and vegetation. A radial spatial pattern of soil properties developed under oak with low visitors’ pressure.     

Critique: building appraisals Third-Way architecture: Stockholm Globe City

Swedish twentieth- century architecture has almost become synonymous with modernism and ‘the architecture of the Welfare state’. Far less is known about the architectural conceptions that came to pass in relation to societal changes at the beginning of the 1980s, which has been termed ‘the end of the Welfare state or the Third Way'. Taking the Stockholm Globe Arena (1982–1989) and the concomitant building complex Globe City as a starting point, the article discusses Third-Way ideology and its relationship to architecture. The hypothesis is that architecture can be seen as a contributing agent in shaping the ideological shift that re-arranges late-twentieth century society, but also, that architecture responds to these shifts.

The article focuses on two themes. First, how conceptions of the new public good were carried through and how new relationships between private and public changed the agenda for planning and building. These transformations are investigated in relation to the production process, whilst the second theme, the capitalisation of the social domain, is analysed in relation to architecture as a cultural and material object.