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[en] The effects of multiple stressors on marine diatom assemblages are still poorly understood. The interactive effects of metals and nutrients were assessed in two coastal biofilms grown at a reference site and a historically contaminated site. The biofilms were exposed in situ to pulse exposures of metals (Zn and Pb) and nutrients (N and P) individually and in combination to mimic patterns of discharge in the study area. The reference community's structure (composition and abundance of taxa) was modified after metals and/or nutrients exposure, but each stressor acted in different way. Irrespective of the stressors or scenario, the abundance of the dominant species Opephora krumbeinii declined, and it is proposed as sensitive species. Nutrient supply favoured the proliferation of certain species with high nutrient tolerances (Fragilaria famelica, Tabularia ktenoeides), whereas metals promoted the colonisation of metal-tolerant species, e.g., Berkeleya fennica, Opephora marina. Simultaneous exposure induced an amplification of levels of accumulated metals, chlorophyll a and EPS contents and triggered the succession of species towards tolerant species with specific growth. Metals seemed to act as a selective factor of metal-tolerant species, and nutrients favoured the proliferation of those species forming zig-zag colonies (Neosynedra provincialis), mucous tubes (Berkeleya spp.) and motile diatoms (Navicula salinicola, Nitzschia incognita), resulting in biofilms with a more complex architecture. The diatom communities from the historically contaminated site were more resistant to pulse exposure, but metals or nutrients loads induced overproduction of mucilage. We propose that growth forms may complement taxonomic approaches and provide a quick and easy way to detect community changes related to metal and nutrient pollution. - Highlights: • The effects of metal and nutrients depend on the exposure history and diatom composition of biofilms. • Diatom growth forms and community structures reflect nutrient and metal exposure. • Nutrients amplify the effects of metal on the community structure and biofilm characteristics in unpolluted sites. • Metal and nutrient inputs promote a more complex biofilm architecture. • Biofilms at a chronically contaminated site were more resistant to metal and nutrients inputs.
[en] This paper is a result of the greenhouse experiments conducted on micronutrient studies in corn. Low yields of corn in some localities despite the application of major elements points out the need for examining the micro-nutrient requirements of corn. Hence, this study aims to determine the fate of added micronutrients on major soil groups with the application of varying levels of nitrogen, phosphorus, and potassium to provide the better understanding of soil micronutrients especially in problem soil. Three soil types, four N-P-K treatments and two micronutrients (Zn and Fe) were used. The test crop was a Tinigib corn variety and sampled at tasseling and silking stages. It was found that NPK combinations of 120-60-30 kg/ha and 60-30-30 kg/ha gave better Fe and Zn fertilizer use efficiency, respectively for a given soil type. Further investigation in major soil types is recommended. (Auth.) 12 refs.; 9 tabs
[en] In this work, we model the biofilm growth at the microscale using a rectangular pore network model in 2D and a cubic network in 3D. For the 2D network, we study the effects of bioclogging on porosity and permeability when we change parameters like the number of nodes in the network, the network size, and the concentration of nutrients at the inlet. We use a 3D cubic network to study the influence of the number of nodes in the z direction on the biofilm growth and on upscalability. We show that the biofilm can grow uniformly or heterogeneously through the network. Using these results, we determine the conditions for upscalability of bioclogging for rectangular and cubic networks. If there is uniform biofilm growth, there is a unique relation between permeability and porosity, K ∼ ϕ2, this relation does not depend on the volume of the network, therefore the system is upscalable. However, if there is preferential biofilm growth, the porosity-permeability relation is not uniquely defined, hence upscalability is not possible. The Damköhler number is used to determine when upscalability is possible. If the Damköhler number is less than 101, the biofilm grows uniformly and therefore the system is upscalable. However, if the Damköhler number is greater than 103, the biofilm growth exhibits a deviation from uniform biofilm growth and heterogeneous growth is observed, therefore upscalability is not possible. There is a transition from uniform growth to preferential growth if the Damköhler number is between 101 and 103.
[en] Highlights: • Pantothenic acid, an essential nutrient, is examined as isolated molecule. • IRMPD spectroscopy is used as structural probe. • A comprehensive computational survey of isomers and conformers is presented. • The favored protonation site is established. • Conformational motifs include multiple hydrogen bonding interactions. Intrinsic properties of pantothenic acid, an essential nutraceutical, are examined. The effect of protonation on the energetic and geometric features of pantothenic acid, generated as gaseous protonated species, are investigated by infrared multiple photon dissociation (IRMPD) spectroscopy over an extended frequency range (800–2000 cm−1 and 2800–3700 cm−1). DFT calculations are exploited to identify the possible structures and predict the absorption spectra at the B3LYP/6-311++G(d,p) level. Two amide-protonated structures, characterized by the most stable binding motifs, account well for the experimental spectrum, thus revealing structurally diagnostic features of potential benefit for the development of highly sensitive and selective nutrient screening.
[en] The purposes of this investigation were to determine the appearance rate of nutrient canals and the aspect of alveolar bone trabecular patterns. 1949 subjects, averages 23 years old, who have normal occlusion were used. The film used in this investigation was full mouth roentgenographic survey. The obtained results were as follows: 1. In the trabecular pattern, coarse form was 35.17%, and fine one was 64.14% in both jaws. 2. The appearance rate of nutrient canals was much higher in mandibular anterior segment(89.13%) than in the maxillary posterior segment(0.86%). 3. In the trabecular forms, small trabecular space and horizontal relation appeared in the mandible, and vertical relation in the maxilla.
[en] The introduction of different applications of nanotechnology will be informed by expert views regarding which (types of) application will be most societally acceptable. Previous research in Northern Europe has indicated that experts believe that various factors will be influential, predominant among these being public perceptions of benefit, need and consumer concern about contact with nanomaterials. These factors are thought by experts to differentiate societal acceptance and rejection of nanotechnology applications. This research utilises a larger sample of experts (N = 67) drawn from Northern America, Europe, Australasia, India and Singapore to examine differences in expert opinion regarding societal acceptance of different applications of nanotechnology within different technological environments, consumer cultures and regulatory regimes. Perceived risk and consumer concerns regarding contact with nano-particles are thought by all experts to drive rejection, and perceived benefits to influence acceptance, independent of country. Encapsulation and delivery of nutrients in food was thought to be the most likely to raise societal concerns, while targeted drug delivery was thought most likely to be accepted. Lack of differentiation between countries suggests that expert views regarding social acceptance may be homogenous, independent of local contextual factors
[en] Sharp chemoattractant (CA) gradient variations near food sources may give rise to dramatic behavioral changes of bacteria neighboring these sources. For instance, marine bacteria exhibiting run-reverse motility are known to form distinct bands around patches (large sources) of chemoattractant such as nutrient-soaked beads while run-and-tumble bacteria have been predicted to exhibit a ‘volcano effect’ (spherical shell-shaped density) around a small (point) source of food. Here we provide the first minimal model of banding for run-reverse bacteria and show that, while banding and the volcano effect may appear superficially similar, they are different physical effects manifested under different source emission rate (and thus effective source size). More specifically, while the volcano effect is known to arise around point sources from a bacterium’s temporal differentiation of signal (and corresponding finite integration time), this effect alone is insufficient to account for banding around larger patches as bacteria would otherwise cluster around the patch without forming bands at some fixed radial distance. In particular, our model demonstrates that banding emerges from the interplay of run-reverse motility and saturation of the bacterium’s chemoreceptors to CA molecules and our model furthermore predicts that run-reverse bacteria susceptible to banding behavior should also exhibit a volcano effect around sources with smaller emission rates. (paper)