The role of riparian trees in maintaining riverbank stability: A review of Australian experience and practice

Riverside vegetation is a significant factor influencing the occurrence and progress of streambed and riverbank erosion. Recent riparian management practice in Australia has focussed on re-establishing or maintaining native riparian vegetation in order to control or prevent erosion as well as regenerate or preserve the complex variety of in-stream and riverside habitats. This work presents an integrated review of field and experimental studies conducted in eastern Australia that evaluate native vegetation's role in mass failure of riverbanks. Several results of these studies have general application and include the following: (1) The presence of riparian forest on riverbanks significantly reduces the likelihood of erosion by mass failure due to reinforcement of riverbank soils by tree roots and this reduced likelihood of mass failure enables a narrower channel cross-section than would otherwise be the case for many Australian coastal streams. (2) A number of Australian tree species have apparently evolved roots that seek the permanent, summer water table in order to survive prolonged dry spells, these root systems are particularly effective in mass failure mitigation due to rooting depths that are commonly greater than 5 m and are sometimes well in excess of 20 m. (3) The so-called “Root-Area-Ratio method” of calculating the shear strength of root-reinforced soil using root tensile strength data and Waldron's [Waldron, L.J., 1977. The shear resistance of root-permeated homogenous and stratified soil. J. Soil Sci. Soc. Am. 41, 843–849] and Wu et al.’s [Wu, T.H., McKinnell, W.P., Swanston, D.N., 1979. Strength of tree roots and landslides on Prince of Wales Island, Alaska. Can. Geotech. J. 16, 19–33] simple root model leads to significant overestimation of the actual root-reinforcement due to (a) breakage or pull-out of roots that taper and narrow beneath the shear plane such that individual roots do not achieve the tensile strength calculated on the basis of root diameter at the shear plane; and/or (b) the fact that the soil mass fails progressively along the length of potential shear plane rather instantaneously across the entire shear plane.     

Quantifying the effects of root reinforcement of Persian Ironwood (Parrotia persica) on slope stability; a case study: Hillslope of Hyrcanian forests,northern Iran

Forest vegetation is known to enhance the stability of slopes by reinforcing soil and increasing its shear resistance through root system. The effects of root reinforcement depend on the morphological characteristics of the root system, the tensile strength of single roots, and the spatial distribution of the roots in soil. In the present study the results of research carried out in order to evaluate the biotechnical characteristics of the root system of Persian Ironwood (Parrotia persica), in northern Iran are presented. Profile trenching method was used to obtain root area ratio (RAR) values for uphill and downhill sides of the individual trees. For each species, single root specimens were sampled and tested for their tensile strength. It was found that root density generally decreases with depth according to an exponential law. Maximum RAR values were located within the first 0.1 m, with maximum rooting depth at about 0.65 m. RAR values ranged from 0.001% at lower depths to 1.39% near the surface, at upper 0.1 m depth. Significant differences of RAR values, rooting depth and root cohesion between uphill and downhill were observed, however, the differences were not significant for number of roots (ANCOVA). Downhill profiles had higher RAR values, rooting depth and root cohesion. In general, root tensile strength tends to decrease with diameter according to a power law, as observed by other researchers. Downhill roots were significantly stronger in tensile strength than uphill ones. Inter-species variation of tensile strength in downhill roots was also observed. The resulting data were used to evaluate the reinforcing effects in terms of increased shear strength of the soil, using Wu/Waldron Model. The root reinforcement provided by Persian Ironwood is about 46.0 kPa in the upper layers and 0.3 kPa in the deeper horizons. The results of Spearman test revealed a significant correlation between RAR and c_r and that best followed by a power law. The results presented in this paper contribute to expanding the knowledge on biotechnical characteristics of Persian Ironwood on slope reinforcement.     

3-D numerical investigations into the shear strength of the soil–root system of Makino bamboo and its effect on slope stability

This study attempts to quantify the reinforcement effect of the Makino bamboo (Phyllostachys makinoi Hayata) root system on the stability of slopeland through numerical analyses and in situ tests. Based on the field surveys of Makino bamboo root morphology, a three-dimensional (3-D) numerical model of the soil–root system consisting of the reverse T-shape tap root and hair roots was developed and successfully applied to the finite element simulations of in situ pull-out tests. In the simulations, the soil mass was simulated by a soil element with a perfect elastic–plastic (or Mohr–Coulomb) material model whereas the root system was simulated by a ground anchor element with a linear elastic material model. In addition, a mechanical conversion model with simple mathematical form, which enables a direct transformation of the ultimate pull-out resistance into the shear strength increment of soil–root system was proposed. The conversion model offered a convenient way to quantify the reinforcement effect of the Makino bamboo root system required for the 3-D slope stability analyses. The numerical results indicated that the shear strength increment of the Makino bamboo soil–root system ranged from 18.4 to 26.3 kPa and its effect on the slope stability was insignificant when compared with those adverse influence factors such as the steep slope angle (=50–70°), shallow root depth (=0.8–1.0 m) and large growth height (>10 m) of the Makino bamboo forest slopeland. It can be also speculated that the tension cracks widespread over the slope surface due to the wind loading acting on the bamboo stems and the sequential rainwater infiltration is the dominating factor in the collapse failure of slopeland. For a Makino bamboo forest slopeland with medium slope (25° < slope angle β < 40°), the reinforcement effect of the Makino bamboo root system can mobilize its maximum stabilization capacity when compared with those of slopeland with mild (β < 25°) and steep slopes (β > 40°). Conclusively, the contribution of the Makino bamboo root system to the stability of slopeland is not as significant as expected.     

Removal of nutrients from wastewater with Canna indica L. under different vertical-flow constructed wetland conditions

Constructed wetlands are becoming increasingly popular worldwide for removing contaminants from domestic wastewater. This study investigated the removal efficiency of nitrogen (N) and phosphorus (P) from wastewater with the simulated vertical-flow constructed wetlands (VFCWs) under three different substrates (i.e., BFAS or blast furnace artificial slag, CBAS or coal burn artificial slag, and MSAS or midsized sand artificial slag), hydraulic loading rates (i.e., 7, 14, and 21 cm d^?1), and wetland operational periods (0.5, 1, and 2 years) as well as with and without planting Canna indica L. The wastewater was collected from the campus of South China Agricultural University, Guangzhou, China. Results show that the percent removal of total P (TP) and ammonium N (NH₄⁺-N) by the substrates was BFAS > CBAS > MSAS due to the high contents of Ca and Al in substrate BFAS. In contrast, the percent removal of total N (TN) by the substrates was CBAS > MSAS > BFAS due to the complicated nitrification/denitrification processes. The percent removal of nutrients by all of the substrates was TP > NH₄⁺-N > TN. About 10% more TN was removed from the wastewater after planting Canna indica L. A lower hydraulic loading rate or longer hydraulic retention time (HRT) resulted in a higher removal of TP, NH₄⁺-N, and TN because of more contacts and interactions among nutrients, substrates, and roots under the longer HRT. Removal of NO₃^?N from the simulated VFCWs is a complex process. A high concentration of NO₃^?N in the effluent was observed under the high hydraulic loading rate because more NH₄⁺-N and oxygen were available for nitrification and a shorter HRT was unfavorable for denitrification. In general, a longer operational period had a highest removal rate for nutrients in the VFCWs.     

Survival of black alder (Alnus glutinosa L.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) seedlings in a reclaimed oil shale mining area

Early survival and growth of black alder, silver birch and Scots pine were investigated on reclaimed extremely stony and heterogeneous calcareous (pH 8) opencast oil shale mining areas (OOSMAs). Biomass allocation, production, leaf and root adaptations, and mineral nutrition in relation to tree species and soil heterogeneity were analysed. The adaptive strategies of tree species in first-year plantations on OOSMA were different. Scots pine allocated 1.5–2 times more biomass into leaves and fine roots than deciduous trees. The lower leaf/fine root biomass ratio was in proportion to the better survival (%) of seedlings, decreasing in the following order: black alder (93%) ≥ Scots pine (83%) > silver birch (64%). Deciduous trees improved mineral nutrition more by fine-root morphological adaptations than Scots pine; e.g. the mean specific root length (SRL, m g^?1) of short roots increased in the following order: Scots pine (62) < black alder (172) < silver birch (314). The effect of soil heterogeneity on growth and adaptations was minor. All studied species suffered from P and N, and deciduous species also from K deficiency. In the first year after planting, black alder was best adapted to the harsh conditions of the post-mining substrate. The approaches of this study can be used for other regions where wastelands require reclamation.     

The effects of exercise training programs on plasma concentrations of proenkephalin Peptide F and catecholamines

To determine if exercise training alters the pattern and magnitude of plasma concentrations of proenkephalin Peptide F and epinephrine, plasma proenkephalin [107–140] Peptide F_ir and catecholamines were examined pre-training (T-1), and after 4- (T-2), 8- (T-3), and 12-weeks (T-4) of training. 26 healthy men were matched and randomly assigned to one of three groups: heavy resistance strength training (Strength, n = 9), high intensity endurance training (Endurance, n = 8), or both training modalities combined (Combined, n = 9). Blood was collected using a syringe with a cannula inserted into a superficial arm vein with samples collected at rest, after each 7 min stage and 5 and 15 min into recovery. With training, all groups observed shifted plasma Peptide F responses to graded exercise, where significant increases were observed at lower exercise intensities. Increases in plasma epinephrine with exercise were observed in all groups. The Combined group saw increases at 25% at T-3 and for 50% at T-2, T-3, and T-4 which was higher than T-1. The Endurance group demonstrated increases for 50% at T-1, T-2, T-3 but not at T-4. The plasma epinephrine response to graded exercise was reduced in the Strength group. Increases in plasma norepinephrine above rest were observed starting at 50%

. The Strength group demonstrated a significant reduction in norepinephrine observed at 100% at T-3 and T-4. Peptide F and catecholamines responses to graded exercise can be altered by different types of physical exercise training. Simultaneous high intensity training may produce adrenal medulla exhaustion when compared to single mode training.     

Pea plant responsiveness under elevated [CO2] is conditioned by the N source (N2 fixation versus NO3− fertilization)

The main goal of this study was to test the effect of [CO₂] on C and N management in different plant organs (shoots, roots and nodules) and its implication in the responsiveness of exclusively N₂-fixing and NO₃⁻-fed plants. For this purpose, exclusively N₂-fixing and NO₃⁻-fed (10 mM) pea (Pisum sativum L.) plants were exposed to elevated [CO₂] (1000 μmol mol⁻¹ versus 360 μmol mol⁻¹ CO₂). Gas exchange analyses, together with carbohydrate, nitrogen, total soluble proteins and amino acids were determined in leaves, roots and nodules. The data obtained revealed that although exposure to elevated [CO₂] increased total dry mass (DM) in both N treatments, photosynthetic activity was down-regulated in NO₃⁻-fed plants, whereas N₂-fixing plants were capable of maintaining enhanced photosynthetic rates under elevated [CO₂]. In the case of N₂-fixing plants, the enhanced C sink strength of nodules enabled the avoidance of harmful leaf carbohydrate build up. On the other hand, in NO₃⁻-fed plants, elevated [CO₂] caused a large increase in sucrose and starch. The increase in root DM did not contribute to stimulation of C sinks in these plants. Although N₂ fixation matched plant N requirements with the consequent increase in photosynthetic rates, in NO₃⁻-fed plants, exposure to elevated [CO₂] negatively affected N assimilation with the consequent photosynthetic down-regulation.     

Influence of slope on root system anchorage of Pinus yunnanensis

In southwestern China, Yunnan pines (Pinus yunnanensis) have been extensively cultivated on barren hills for reforestation and ecological engineering. The objective of this work is to study the influences of slope gradient on anchorage of root systems of P. yunnanensis. Pulling experiments were carried out at low (5–6°), moderate (25–26°) and high gradient (42–43°) by using selected 15-year-old P. yunnanensis. The results showed that the anchorage resistances induced by the slope gradient were significantly (P < 0.01) different from each other and followed in the order of high slope > moderate slope > low slope. Anchorage strength of upslope-grown roots increased with size and length of first-order lateral roots as well as the number of second-order lateral roots. Contributions of upslope-grown roots for preventing plants from overturning varied considerably between those from different slopes. The contribution of roots growing on upslope side on high slope to the anchorage of root system reached 50%, whereas those on moderate and low slopes were about 44% and 37%, respectively. It was concluded that the anchorage resistance was closely related to slope gradient and root distribution, while upslope-grown roots were positively related to anchorage resistance.     

Efficient nitrogen removal in a pilot system based on upflow multi-layer bioreactor for treatment of strong nitrogenous swine wastewater

In order to prevent the toxic effect caused by high strength ammonium in a swine wastewater treatment system, a patented upflow multi-layer bioreactor (UMBR) as a pre-anoxic tank was applied to a pilot-scale plant with a treatment capacity of 5 m³/d. This plant was operated for 4 months at a high IR ratio in the range of 10–17, in order to alleviate the toxic effects caused by high strength ammonium. A computational fluid dynamic (CFD) analysis was also conducted to design and configure the rotating distributors in the UMBR. At an IR ratio of about 17, the influent NH₄⁺-N (1169 mg N/L) was diluted to less than 80 mg N/L at the head of the UMBR, and then was completely nitrified (about 98.3%) in the aeration tank, without any inhibition caused by high strength ammonium. The nitrate at a concentration of about 58.2 mg N/L recycled from the aeration tank was completely denitrified in UMBR #1, which was operated at an actual hydraulic retention time (HRT) of 3.5 h.     

Características y factores asociados a caídas en pacientes con enfermedad cerebrovascular

Objectiveto asses the characteristics and factors associated with falls during hospitalisation among elderly stroke patients.Material and methodswe studied 1,410 subjects (60.1% female), aged 65 years and older (80.6 ± 6.9 years), admitted to a geriatric stroke unit between 2000 and 2003. We recorded demographic, clinical and functional variables and evaluated the characteristics and management of falls. The variables showing an association with falls in bivariate analyses were subsequently included in a multivariate logistic regression analysis.Resultsthe incidence rate of falls was 10.49% in 115 patients. The variables showing statistical association (p < 0.05) with falls were age (78.7 vs 80.8) and gender (10.5% male vs 6.6% female), arm strength (2.8 vs 2.3), leg strength (3.2 vs 2.6) and being classified in the group with moderate stroke (47.8%) compared with patients without falls (29.3%). Falls were more frequent in patients with depression (13% vs 7%) and delirium (27% vs 6%). The variables that remained significant in the multivariate logistic regression model for falls were: delirium (OR = 4.691 [2.930-7.511]), mild stroke (OR: 0.347 [0.154-0.782]), age (OR = 0.958 [0.929-0.987]), depression (OR = 1.760[1.095-2.828]), arm strength (OR = 1.233 [1.058-1.438]), and Barthel Index prior to the fall (OR = 1.013 [1.002-1.024]).Conclusionspatients with falls are younger, with a higher previous functional status and with lesser neurological severity on admission. The presence of depression and delirium are frequently associated.     

Wastewater treatment by using kenaf in paddy soil and effect of dissolved oxygen concentration on efficiency

We previously reported that kenaf (Hibiscus cannabinus L.) planted in a zeolite-bed filter-ditch system provided highly effective treatment of wastewater. Here we compared that system with treatment in fallow paddy fields irrigated in different ways in a greenhouse. Paddy soil was a useful alternative to zeolite as the bed filter material. The efficiency of removal of N and P under furrow irrigation and flooding was 82–92% of that of the zeolite system. Most kenaf roots were distributed in water with a high dissolved oxygen (DO) concentration and a high redox potential; few roots grew in reducing soil under water. The roots distributed in the water contributed most to wastewater treatment. A low DO concentration (0.3 mg L⁻¹) decreased the efficiency of N and P removal. However, nightly low DO concentration (near 0 mg L⁻¹) alternating with daily high DO concentration did not seriously restrict the efficiency. An increase of alpha-naphthylamine oxidation activity in kenaf roots at low DO concentration is discussed in regard to induction of an oxygen-protective enzyme.     

Effect of ligand congeniality on energy transfer reaction between photo-excited tris(bipyridine)ruthenium(II) and chromate(III) complexes in aqueous solutions

Energy-transfer rate-constants from photo-excited [Ru(N–N)₃]²⁺ (N–N = 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (4dmb), 5,5′-dimethyl-2,2′-bipyridine (5dmb)) to [Cr(O–O)₃]³⁻ (O–O²⁻ = ox²⁻ ((COO⁻)₂), mal²⁻ (CH₂(COO⁻)₂)) and [Cr(CN)₆]³⁻ in encounter complexes were evaluated in aqueous solutions containing alkali metal ion. The rate constant depends on the molecular size of the ruthenium(II) complex: 1.8 × 10⁸ s⁻¹ for [Ru(bpy)₃]²⁺ (molecular radius, r = 5.8 Å), 1.4 × 10⁸ s⁻¹ for [Ru(5dmb)₃]²⁺ (r = 6.1 Å) and 0.96 × 10⁸ s⁻¹ for [Ru(4dmb)₃]²⁺ (r = 6.7 Å) in the system of [Ru(N–N)₃]²⁺–[Cr(ox)₃]³⁻ in aqueous solution. However, the rate constant is much more sensitive to the chromate(III) complex than to ruthenium(II) complex; 1.8 × 10⁸ s⁻¹ and 0.43 × 10⁸ s⁻¹ for [Cr(ox)₃]³⁻ (r = 4.0 Å) and [Cr(mal)₃]³⁻ (r = 4.2 Å) in the [Ru(bpy)₃]²⁺–[Cr(O–O)₃]³⁻ systems, respectively. We conclude that the congeniality between the donor’s and acceptor’s ligands in encounter complex plays an important role in energy transfer in aqueous solution.     

Pollination biology of Eriocaulon parkeri in Connecticut

Eriocaulon parkeri B. L. Robinson is a monoecious, pioneer species of tidal mudflats that displays characteristics that suggest outcrossing as a preferred breeding system. Analyses of breeding system dynamics, fruit set, and pollen and seed viabilities were undertaken in Connecticut and Wisconsin to test the hypothesis of entomophyly and outcrossing as a preferred breeding strategy. Potential pollinators included syrphid and long-legged flies. Seed viability was estimated at 94 ± 16% (n = 133); pollen viability at 88 ± 13%. Pollen production averaged ∼500 grains per flower. Pollen–ovule ratios within inflorescences averaged 196:1, suggesting facultative autogamy. Seed set in natural populations averaged 74%, not significantly different between early and late season plants or between greenhouse controls and hand pollinations. Emasculated plants produced small amounts of seed under controlled greenhouse conditions. Pollen tube growth through the styles of E. aquaticum, a related species, was much more prevalent than that of E. parkeri. Results suggest that E. parkeri relies heavily on geitonogamy for seed production. Some seed may be produced by agamospermy.     

Nitrate removal from three different effluents using large-scale denitrification beds

Simple technologies that remove nitrate from effluents and other point discharges need to be developed to reduce pollution of receiving waters. Denitrification beds are lined containers filled with organic carbon (typically wood chip or coarse sawdust) and are a technology that is proving promising. Water containing NO₃^? (treated effluent or agricultural drainage) is passed through the bed and the wood chips act as an energy source for denitrifying bacteria that convert NO₃^? to N gases. There are few data on the efficiency of NO₃ removal in large-scale beds. We report here NO₃^? removal results from three large denitrification beds with volumes of 83, 294, and 1320 m³ treating dairy shed effluent, treated domestic effluent and glasshouse effluent, respectively. Nitrate was nearly completely removed from the dairy shed effluent (annual load of 31 kg N) and domestic effluent (annual load 365 kg N). In these beds, NO₃^? removal, presumably by denitrification, was limited by NO₃^? concentration. However, the bed treating glasshouse effluent was overwhelmed by very high NO₃^? concentration (about 250 g N m^?3) and high flow rates (about 150 m³ d^?1) but still reduced NO₃^? concentration to about 150 g N m^?3. For this bed, long-term NO₃^? removal was between 5 and 10 g N m^?3 of bed material when NO₃^? was non-limiting and was similar to rates reported for other smaller denitrification beds. As expected, organic N, ammonium and phosphorus were not removed from any of the effluents following passage through the beds. Our results suggest that denitrification beds are a relatively inexpensive system to construct and operate, and are suitable for final treatment of a range of NO₃^?-laden effluents.     

Structure and water permeability of fully hydrated diphytanoylPC

Diphytanoylphosphatidylcholine (DPhyPC) is a branched chain lipid often used for model membrane studies, including peptide/lipid interactions, ion channels and lipid rafts. This work reports results of volume measurements, water permeability measurements P_f, X-ray scattering from oriented samples, and X-ray and neutron scattering from unilamellar vesicles at T = 30 °C. We measured the volume/lipid V_L = 1426 ± 1 Å³. The area/lipid was found to be 80.5 ± 1.5 Å² when both X-ray and neutron data were combined with the SDP model analysis (Ku?erka, N., Nagle, J.F., Sachs, J.N., Feller, S.E., Pencer, J., Jackson, A., Katsaras, J., 2008. Lipid bilayer structure determined by the simultaneous analysis of neutron and X-ray scattering data. Biophys. J. 95, 2356–2367); this is substantially larger than the area of DOPC which has the largest area of the common linear chain lipids. P_f was measured to be (7.0 ± 1.0) × 10^?3 cm/s; this is considerably smaller than predicted by the recently proposed 3-slab model (Nagle, J.F., Mathai, J.C., Zeidel, M.L., Tristram-Nagle, S., 2008. Theory of passive permeability through lipid bilayers. J. Gen. Physiol. 131, 77–85). This disagreement can be understood if there is a diminished diffusion coefficient in the hydrocarbon core of DPhyPC and that is supported by previous molecular dynamics simulations (Shinoda, W., Mikami, M., Baba, T., Hato, M., 2004. Molecular dynamics study on the effects of chain branching on the physical properties of lipid bilayers. 2. Permeability. J. Phys. Chem. B 108, 9346–9356). While the DPhyPC head–head thickness (D_HH = 36.4 Å), and Hamaker parameter (H = 4.5 × 10^?21 J) were similar to the linear chain lipid DOPC, the bending modulus (K_C = 5.2 ± 0.5 × 10^?21 J) was 30% smaller. Our results suggest that, from the biophysical perspective, DPhyPC belongs to a different family of lipids than phosphatidylcholines that have linear chain hydrocarbon chains.     

Endothelium oriented differentiation of bone marrow mesenchymal stem cells under chemical and mechanical stimulations

Bone marrow mesenchymal stem cells (MSCs) have multi-differentiation capability. Their endothelial cell (EC) oriented differentiation is the key to vasculogenesis, in which both mechanical and chemical stimulations play important roles. Most previous studies reported individual effects of VEGF or fluid shear stress (SS), when MSCs were subjected to shear stress of 10–15 dyn/cm² over 24 hr. In this paper, we investigated responses of MSCs from young Sprague Dawley rats to shear stress, VEGF and the combination of the two stimuli. Our study showed that the combined stimulation of shear stress and VEGF resulted in more profound EC oriented differentiation of MSCs in comparison to any individual stimulation. Furthermore, we subjected MSCs to prolonged period of fluid shear stimulation, i.e. 48 hr rather than 24 hr, and increased the magnitude of the shear stress from 10 dyn/cm² to 15, 20 and 25 dyn/cm². We found that without VEGF, the endothelium oriented differentiation of MSCs that was seen following 24 hr of shear stimulation was largely abolished if we extended the shear stimulation to 48 hr. A similar sharp decrease in MSC differentiation was also observed when the magnitude of the shear stress was increased from 10–15 dyn/cm² to 20–25 dyn/cm² in 24 hr shear stimulation studies. However, with combined VEGF and fluid shear stimulation, most of the endothelial differentiation was retained following an extended period, i.e. at 48 hr, of shear stimulation. Our study demonstrates that chemical and mechanical stimulations work together in determining MSC differentiation dynamics.     

Ionic luminescent cyclometalated Ir(III) complexes with polypyridine co-ligands

Two novel ligands containing a functionalized N ∧ N chelating moiety (pbpy-OBut and tpy-COOH, respectively) were treated with [Ir(ppy)₂(μ-Cl)]₂ (ppy = 2-(2-pyridyl)phenyl), leading to the cationic cyclometalated complexes [Ir(ppy)₂(pbpy-OBut)]⁺ (2) (pbpy-OBut = 4-{4′-(4-phenyloxy)-6′-phenyl-2,2′-bipyridyl}butene) and [Ir(ppy)₂(tpy-COOH)]⁺ (3) (tpy-COOH = 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine). Complexes 2 and 3 exhibit intense room temperature luminescence both in solution and as solid films. Assignment of the emissive behavior to a ³LLCT (ppy-to-N ∧ N) excited state is proposed.     

Effect of different macrophytes in abating nitrogen from a synthetic wastewater

An experiment conducted in an unheated glasshouse from October 2006 to March 2008 studied the efficiency of different macrophytes in reducing NO₃-N and NH₄-N concentrations and loads in synthetic wastewaters. The experimental setup consisted of plastic tanks, filled with gravel and vegetated with Carex elata All., Juncus effusus L., Phragmites australis (Cav.) Trin., Typhoides arundinacea L. Moench (syn Phalaris arundinacea L.) var. picta and Typha latifolia L. There was also a control without vegetation. From January to July, a solution of 50–60 ppm of NH₄-N and NO₃-N was applied monthly; then the input concentration was doubled. The total load at the end of the experimental period was 70.4 g/m² of NO₃-N and 67.3 of NH₄-N. At the end of each month, water was discharged from the tanks and analysed to determine the two nitrogen forms. At the end of the experiment, 33 g/m² of total N (almost 24% of applied N) had disappeared in the control. Among species, the highest abatement was detected in T. latifolia (72 g/m², almost 52% of applied N) and the lowest in J. effusus (35%).A weekly chemical analysis in July showed that a large amount of NH₄-N quickly disappeared in all treatments, while NO₃-N only decreased in the vegetated tanks. In December, NH₄-N had similar dynamics, while NO₃-N increased.All water volumes entering and exiting the tanks were measured in order to evaluate evapotranspiration. T. latifolia showed the highest water consumption, reaching a cumulative value of above 1000 mm.At the end of the experiment, J. effusus presented the highest amount of nitrogen stored in the aerial parts (5.63 g/m²) and T. latifolia the lowest (1.92 g/m²).     

Primary stability of tibial plateaus under dynamic compression-shear loading in human tibiae – Influence of keel length,cementation area and tibial stem

The objective of our study was to evaluate the impact of the tibial keel & stem length in surface cementation, of a full cemented keel and of an additional tibial stem on the primary stability of a posterior stabilised tibial plateau (VEGA® System Aesculap Tuttlingen, Germany) under dynamic compression-shear loading conditions in human tibiae.We performed the cemented tibial plateau implantations on 24 fresh-frozen human tibiae of a mean donor age of 70.7 years (range 47–97). The tibiae were divided into four groups of matched pairs based on comparable trabecular bone mineral density. To assess the primary stability under dynamic compression shear conditions, a 3D migration analysis of the tibial component relative to the bone based on displacements and deformations and an evaluation of the cement layer including penetration was performed by CT-based 3D segmentation.Within the tested implant fixation principles the mean load to failure of a 28 mm keel and a 12 mm stem (40 mm) was 4700 ± 1149 N and of a 28 mm keel length was 4560 ± 1429 N (p = 0.996), whereas the mean load to failure was 4920 ± 691 N in full cementation (p = 0.986) and 5580 ± 502 N with additional stem (p = 0.537), with no significant differences regarding the dynamic primary stability under dynamic compression-shear test conditions.From our observations, we conclude that there is no significant difference between a 40 mm and a 28 mm tibial keel & stem length and also between a surface and a full cementation in the effect on the primary stability of a posterior stabilised tibial plateau, in terms of failure load, migration characteristics and cement layer thickness including the penetration into the trabecular bone.     

Effect of mercury and gold on growth,nutrient uptake,and anatomical changes in Chilopsis linearis

Plants of Chilopsis linearis were grown with 0, 50, 100, and 200 μM Hg [as Hg(CH₃COO)₂] and 0 and 50 μM Au (as KAuCl₄) in hydroponics. The results showed that seedling grown with 50 μM Au + 50 μM Hg and 50 μM Au + 100 μM Hg had roots 25 and 55% shorter than control roots, respectively. The element uptake determination using ICP/OES demonstrated that Hg at 50 and 100 μM (with and without Au) significantly increased (p < 0.05) the S concentration in leaves. On the other hand, the concentration of Fe significantly increased in roots of plants treated with Au–Hg. In addition, the stems of plants treated with Hg at 100 μM, with and without Au, had 239 and 876 mg Hg/kg dry biomass (d wt), respectively. Also, at 50 μM Hg, with and without Au, stems accumulated 375 and 475 mg Hg/kg d wt. The Hg concentration in leaves (287 mg Hg/kg d wt) was higher (p < 0.05) for the treatment containing 50 μM Au + 100 μM Hg. Without Au, the Hg concentration in leaves decreased to 75 mg Hg/kg d wt. Toxicity symptoms induced by Hg in cortex cells and the vascular system were lower in plants exposed to 50 μM Au + 50 μM Hg compared to plants exposed to 50 μM Hg only. Further, the SEM micrographs revealed deposition of Au–Hg particles inside the root. Although the concentrations of Hg used in this study showed different degree of toxicity, the plants displayed good agronomic value.