The return of degraded stream ecosystems by using positive impacts from near‐natural sections: a new practical guide for restorations

Streams in North Rhine‐Westphalia (Germany) are frequently impacted by hydromorphological degradation leading to a loss of sensitive species and a reduction in diversity. These findings mean that the final objective of the European Water Framework Directive to achieve the good ecological status will be failed for a large number of streams. In a holistic approach, a new concept, considering the cost efficiency, has been developed to enhance habitats by morphological changes. This guide serves as a basis for stream restoration projects. The theoretical background is that near‐natural sections influence adjacent sections of medium habitat quality positively by migration of type‐specific sensitive organisms. The preconditions are a local taxa richness in the catchment area, the reduction of nutrients and organic matter, and the guarantee of free movement. This so‐called ‘spreading effect’ can be measured upstream and downstream. The length of by these means valourized sections depends on the stream type and on the biological quality component.     

Influence of acid hydrolysis on thermal and rheological properties of amaranth starches varying in amylose content

BACKGROUND: The granules of amaranth starch are very small compared with starches from other sources. In the current work, amaranth starches with different amylose contents were treated with hydrochloric acid as a function of time in order to study the effect of acid treatments on starches. Differential scanning calorimetry and dynamic oscillation in shear were employed to analyse the thermal and rheological properties of acid‐modified amaranth starch. RESULTS: Results showed that gelatinisation temperatures and enthalpy change of gelatinisation (ΔH) decreased steeply initially, and had a slight increase with further treatment up to 12 h then decreased, an outcome that reflected distinct resistance to acid with various amylose contents. Rheological parameters of storage and loss moduli during heating, cooling and frequency sweep of modified starches reflected the differential scanning calorimetry results by decreasing in value as the time of acid hydrolysis increased. CONCLUSION: With amylose content increase, the effects of acid hydrolysis on gelatinisation temperatures became less pronounced. Nevertheless, prolonged acid hydrolysis decreased the storage and loss moduli, with the starch pastes becoming more liquid‐like. Copyright © 2012 Society of Chemical Industry     

Damage analysis of microwave‐dried materials

The aim of this article is to analyze the drying‐induced stresses and destruction of ceramic‐like materials during their microwave drying. The kinetics of microwave drying at various microwave power levels are determined experimentally and numerically, and the distributions of temperature and moisture content in the tested samples are visualized with infrared camera and presented graphically. The experiments are performed on kaolin‐clay samples, where destruction provoked by microwave drying is visualized on photographs taken with the photo camera and microscope. The thermo‐hydro‐mechanical model of drying elaborated by authors is used to determine the distribution of stress components and to calculate the effective stress required to induce the failure of material. The effective stress is formulated with the use of the energetic criterion, and the material spots prone to damage are predicted numerically. The numerically predicted spots are compared with the experimentally appointed places of material damage and a good adherence of the numerical predictions with experiments is confirmed. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Particle formation and characteristics of Celecoxib-loaded poly(lactic-co-glycolic acid) microparticles prepared in different solvents using electrospraying

Microparticles were fabricated for pharmaceutical purposes using electrospraying with the aim to determine the effect of the solvent(s) used. Particles of poly(lactic-co-glycolic acid) (PLGA) and the drug Celecoxib were prepared from acetone, acetonitrile and acetone:methanol with different polymer and drug concentrations. The solvent power, evaporation rate and electrical conductivity of the solvents all had a significant effect on the particle formation process as well as the particle characteristics and drug release profile. Particles were near-spherical and between 2 and 7 μm in diameter with smooth or corrugated surfaces. The drug release rate was mainly dependent on particle size, with larger particles showing slower release. The solvent in which PLGA was poorly soluble resulted in small grainy particles that disintegrated instantaneously with full drug release. It may be concluded that the selection of an appropriate solvent may be a useful way to control particle characteristics and drug release profiles when using electrospraying.     

Fully mass printed loudspeakers on paper

We report on the first fully mass printed large-area piezoelectric loudspeakers on paper. All functional layers were printed by means of flexography, alternatively screen and stencil printing, on conventional paper without any surface modification. We used polymers for the electrodes (poly(3,4-ethylendioxythiophene)/poly(4-styrenesulfonate, PEDOT:PSS)) as well as the piezoelectric layer (poly(vinylidene fluoride-trifluorethylene), P(VDF-TrFE)). It could be demonstrated that low-cost devices for mass markets can be realized successfully with the developed technology and process. Besides technical challenges, electrical and acoustic properties of printed speakers are investigated, taking the mechanical properties of the substrate and size of the active piezoelectric area into account. A sound pressure level up to 80 dB could be achieved.     

Cells as factories for humanized encapsulation

Biocompatibility is of paramount importance for drug delivery, tumor labeling, and in vivo application of nanoscale bioprobes. Until now, biocompatible surface processing has typically relied on PEGylation and other surface coatings, which, however, cannot minimize clearance by macrophages or the renal system but may also increase the risk of chemical side effects. Cell membranes provide a generic and far more natural approach to the challenges of encapsulation and delivery in vivo. Here we harness for the first time living cells as "factories" to manufacture cell membrane capsules for encapsulation and delivery of drugs, nanoparticles, and other biolabels. Furthermore, we demonstrate that the built-in protein channels of the new capsules can be utilized for controlled release of encapsulated reagents.     

Non-planar Dzyaloshinskii spirals and magnetic domain walls in non-centrosymmetric systems with orthorhombic anisotropy

The basic micromagnetic models of Landau, Lifshitz, and Dzyaloshinskii, are extended by an anisotropy term with two independent parameters. The resulting ground states of the magnetic domains and the domain-wall profiles are discussed for crystal lattices with orthorhombic unit cells. In these simple geometries, the magnetization is not confined to a single plane. Depending on the relations between the spin-stiffness, anisotropy, and Dzyaloshinskii-Moriya interaction several different zero-temperature phases of the magnetic structure are found. The corresponding phase diagrams are obtained numerically. Analytical results are given for some special cases. The studied model is of particular relevance for magnetic wires, nanostripes and ultrathin magnetic films deposited on non-magnetic surfaces.     

Dissolved Oxygen Demand at the Sediment-Water Interface of a Stream: Near-Bed Turbulence and Pore Water Flow Effects

A microbial dissolved oxygen (DO) uptake model was developed for a stream bed, including the effect of turbulence in the flow over the bed and pore water flow in the porous bed. The fine-grained sediment bed has hydraulic conductivities 0.01 ≤ k ≤ 1??cm/s, i.e., sediment particle diameter 0.006 ≤ ds ≤ 0.06??cm. The pore water flow is driven by pressure fluctuations at the sediment-water interface, mostly attributable to near-bed coherent motions in the turbulent boundary layer above the sediment bed. An effective mass transfer coefficient (De) coupled to a pore water flow model was used in the DO transport and DO uptake model. DO flux across the sediment-water interface and into the sediment, i.e., sedimentary oxygen demand (SOD), was related to hydraulic conductivity and microbial oxygen uptake rate in the sediment and shear velocity at the sediment-water interface. Simulated SOD values were validated against experimental data. For hydraulic conductivities of the sediment bed up to k ≈ 0.01??cm/s, the pore water flow effect on SOD was found negligible. Above this threshold, the effective mass (DO) transfer coefficient in the sediment bed (De) becomes larger as the hydraulic conductivity (k) becomes larger as the interstitial flow velocities increase; consequently, DO penetration depth increases with larger hydraulic conductivity of the sediment bed (k), and SOD increases as well. The enhancement of vertical DO transport into the sediment bed is strongest near the sediment-water interface, and rapidly diminishes with depth into the sediment layer. An increase in shear velocity at the sediment-water interface also enhances DO transfer. Shear velocity increases at the sediment-water interface will raise SOD regardless of the maximum oxidation rate if the hydraulic conductivity is above the threshold of k ≈ 1??cm/s. The relationship is nearly linear when U*<0.8??cm/s. At shear velocity U* = 1.6??cm/s, SOD for oxidation rates μ = 1000 and 2000??mg?l-1?d-1 are almost five times larger than those with no pore water flow. When pore water transport of DO is not limiting, SOD is a linear function of oxygen demand rate μ in the sediment when 0 ≤ μ ≤ 200??mg?l-1?d-1.     

A demonstration site-built solar air collector using selective surface glazing, Boston, Massachusetts

A 450 ft ‘site-built’ air collector was completed in February 1981 in Boston, Massachusetss. The collector uses the Airco/Guardian ‘Passive Solar Glass’ with a selective surface coating on the inner lite of the collector's double glazing. This paper discusses the issues and theory that led to the building of the collector and estimates performance for the system. Preliminary data taken in late winter indicates that the system will perform seasonally as predicted.