Unrestricted ramping rates and long‐term trends in the food web metrics of a boreal river

Long‐term monitoring of the food web of a regulated hydropeaking river was conducted to assess if previously documented effects of changing ramping rates (RRs) were maintained with the addition of 6 years of data. Using carbon and nitrogen stable isotope analyses, we hypothesized that: (1) macroinvertebrates and fish inhabiting areas below peaking hydrodams would be higher in δ¹⁵N and lower in δ¹³C due to increased flow velocity and the influence of light respired dissolved inorganic carbon, relative to those sampled from areas with a natural flow regime; (2) the increase in δ¹⁵N of macroinvertebrates would lead a shorter food web length in the regulated river, but δ¹³C and niche width would be similar between the restricted and unrestricted RR periods (i.e., the BACI analysis); and (3) isotopic metrics (e.g., δ¹³C, δ¹⁵N, niche width [SEA_B], and food chain length [Δ¹⁵N]) would correlate with variations in flow characteristics through time. Consistent with previous analysis conducted over a shorter time period, a shift toward higher δ¹⁵N values was observed for both fish and invertebrates, but, contrarily, only invertebrates (not fish) had a lower δ¹³C value downstream of the dam. Over the long term, the before‐after‐control‐impact analysis found no effect of RRs on any of the food web metrics, implying that the change in operation did not affect the river food web. However, analysis of the time series data indicated that flow metrics and trophic metrics were often correlated, including a negative effect of RR (invertebrates) and discharge (fish) on food chain length. This study illustrates the difficulty in detecting changes in food web structure and function under changing flow regime influenced by natural and anthropogenic effects. As such, this study highlights the need for considering large spatial and temporal scales to differentiate between confounding effects of climate, natural variability, and altered flow regimes on food webs in regulated rivers.     

Flash pyrolysis of wood in a cyclone reactor

This paper reports the first results of an experimental study of the continuous flash pyrolysis of wood sawdust in a cyclone reactor between 893 and 1330 K. The reaction produces low fractions of char (4%) and the gasification yield increases from 0% at about 800 K to 90% at around 1330 K with a constant volume fraction of CO and H₂ (≈73%) and an increasing fraction of light hydrocarbons (up to 50% mass fraction). The heating value of the gas reaches 19 000 kJ m⁻³ STP for the highest temperatures. The wood particles mainly heated by radiation and solid convection react in less than 1 s while the carrier gas (residence time of the order of 0.05 s) seems to be only weakly heated. The 46.2 × 10⁻⁶ m³ cyclone reactor can operate with excellent stability for wood flow rates up to 0.35 kg h⁻¹ at a wall temperature of 1330 K. The cyclone seems to be very efficient for carrying out reactions of the solid → fluids type but more accurate determination of process parameters such as gas and solid residence times and heat transfer efficiencies are required to gain a better understanding of the behaviour of such a high temperature reactor.     

A performance study of plane wave finite element methods with a Padé-type artificial boundary condition in acoustic scattering

This paper proposes an original numerical method and studies its performance for solving high-frequency scattering problems involving elongated scatterers. The approach is based on coupling a high-order Padé-type non-reflecting boundary condition with plane wave finite element formulations. It is shown that for some numerical examples the approximate solution of suitable accuracy can be obtained using a small number of degrees of freedom.     

Preparation of Phospholipid Multilayer Patterns of Controlled Size and Thickness by Capillary Assembly on a Microstructured Substrate

By dragging a phospholipid solution on microstructured silicon surfaces, phospholipid molecules are selectively deposited inside the microstructures to get regular phospholipid multilayer patterns of controlled thickness over a large scale (～cm²). By varying the dragging speed, the thickness of the patterns varies between 28 and 100 nm on average (7 to 25 bilayers). Electroswelling of phospholipid multilayer patterns leads to the formation of giant liposomes of controlled size and narrow size distributions.     

Effects of light,temperature and water activity on the kinetics of lipoxidation in almond-based products

Lipoxidation in almond-derived products was investigated using the chemiluminescence (CL) and thiobarbituric acid-reactive substances (TBARS) methods to detect the first and later reaction products, respectively. The effects of light during storage at 5 °C, 22 °C and 40 °C were studied, as well as the effects of combined heat/water activity treatments in the 60–120 °C and 0.38–0.72 range. During storage, light was found to enhance the CL and TBARS values, and specific responses were observed in almond paste and the final Calisson product. During the heating of almond paste, as the initial water activity (a_w) increased, the CL rate constants increased during heating to 60 °C and 80 °C, but interestingly, these values decreased during further heating to 120 °C, whereas the maximum TBARS rate constants occurred at a_w 0.57 at all the heating temperatures tested. The activation energies, based on the CL and TBARS values, decreased specifically when the a_w increased from 0.38 to 0.72, giving overall values ranging from110 kJ mol⁻¹ to 60 kJ mol⁻¹. Likewise, in the same water activity range, the temperature-dependent rate constant enhancing factor (Q₁₀) decreased from 3.3 to 1.6.     

A novel,fast and accurate chemiluminescence method for measuring lipoxidation in almonds and almond-based products during processing and storage

An analytical method for investigating lipoxidation processes based on soft extraction and chemiluminescence (CL) detection methods was developed and tested on almond and almond-derived foodstuffs. The TBARS method, which detects any carbonyls generated by lipoxidation, was used for comparative purposes. When developing the present method, the classical chloroform–methanol procedure was first used to extract the CL reacting substances initially generated, and solubilizing agents were then screened for optimal extraction. In the detection stage, cytochrome C was used as a reference substance for screening the CL signal enhancers. The method presented here was based on an extraction step with a dimethylsulfoxide/Gum Arabic mixture, and hemin was used to enhance the luminescence signal. This method accurately detects the lipoxidation processes triggered by the physical and chemical treatments of all kinds which are applied during almond processing. The simultaneous use of the present method and the TBARS method gave a broader picture of the chemical interactions involved, including the lipoxidation process.     

Surface potential measurements of Langmuir films of azo dye/liquid crystal mixtures

Two-component films of a non-amphiphilic azo dye and a liquid crystal with strongly polar –CN group were studied at an air–water interface on the basis of the surface potential–mean molecular area dependence recorded simultaneously with the surface pressure–mean molecular area isotherm. Additionally, the morphology of the films was monitored with the aid of Brewster angle microscope. A conventional Langmuir technique was used to form dye/liquid crystal films during reduction and expansion of an area occupied by the molecules. From the surface potential value, the effective dipole moment in the first monolayer formed on the water was calculated. Moreover, the number of molecules with dipole moments directed from the water to the air with respect to those directed towards water was estimated. The influence of the two components' miscibilities upon the surface potential after addition of the dye to the liquid crystal was determined.     

Influence of the suspension flocculated state on the microstructure of alumina spheres elaborated by colloidal granulation

A process of granulation by a colloidal method based on ceramic powder agglomeration makes it possible to produce millimetric spheres with a very homogeneous distribution in terms of shape and size. The starting suspension consists of a mixture of alumina submicrometer particles and silica nanoparticles such as mSiO₂/mAl₂O₃ = 1.1%. Heterocoagulation between the two oxides occurs forming a flocculated network the structure of which can be modified by a shear application. The outer appearance of the spheres is nearly perfect whereas the inner structure exhibits some defects (cracks and porosity). It has been shown that the green spheres are more porous as well as the grains of the starting suspension are less flocculated. During the drying step, the high mobility of these agglomerates increases the overall density on the surface and leads to the formation of a spherical empty cavity in the sphere centre.     

Effects of an encounter group experience on self-perception and interpersonal relations.

Conducted a controlled laboratory investigation of an encounter group experience involving 24 Ss. All Ss 1st participated in a group discussion and rated each other and self on liking, trust, openness, and relaxation. A week later, 1/2 of the Ss participated in a 2-day group encounter and, subsequently, all Ss met again in discussion and were rerated on the same values by each other, self, and independent Os. Results show the encounter Ss improved in self concept, intragroup cohesiveness and liking, and ability to relate to others. No such changes were found for the controls. Negatively, however, the Os did not find any difference between experimental Ss and controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fifth International Deer Biology Congress

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Fifth International Deer Biology Congress