Precipitation, enhanced

The environmental impact of hormones seems to be mainly related to liquid effluents. However, in the light of the high levels of hormones present in solid matrices such as manure or sludge from WWTP with poor hormone removal rates (e.g. enhanced precipitation [116]) there, it is still a need to implement treatment processes to efficiently remove hormones from sludge and manure. 

Microbes are ubiquitous in the subsurface environment and as such may play an important role in groundwater solute behavior. Microbes in the subsurface can influence pollutants by solubility enhancement, precipitation, or transformation (biodegradation) of the pollutant species. Microbes in the groundwater can act as colloids or participate in the processes of colloid formation. Bacterial attachment to granular media can be reversible or irreversible and it has been suggested that extracellular enzymes are present in the system. Extracellular exudates (slimes) can be sloughed-off and act to transport sorbed materials [122]. The stimulation of bacterial growth in the subsurface maybe considered as in situ formation of colloids. 

When the sample has been passed through the chromatography column in Basic Protocol 1, the isolates are in a solvent mixture (hexane/acetone) that can be used for crystallization after saturating by evaporation and enhancing precipitation. If a different solvent pair is necessary for crystallization, the hexane/acetone may be eliminated in a rotary evaporator and the new solvent pair may be added to the concentrate. 

Streamflow discharge of major Siberian rivers into the Arctic Ocean has increased in recent years and is associated with a warmer climate and enhanced precipitation in the river basins. ... 

In the above equation the removal of C02, for example during photosynthesis, will enhance precipitation of CaC03. Likewise, the reverse reaction of respiration or decay of organic matter (for simplicity expressed as CH20) will result in dissolution of calcium carbonate (reaction 3). 

HeUsing K. Immune reactions in polysaccharide media Polysaccharide-enhanced precipitation reactions with antigens of various sizes. Biochem J 1969 114 145-9. 

Solvent dewaxing Solvent-enhanced precipitation to remove waxes and improve low temperature fluidity of lube base stocks. 

Solvent deasphalting Solvent-enhanced precipitation process to remove asphaltenes from heavy lube base stocks and for improving the feed quality of catalytic cracker feed. 

Detailed microstructural investigation [12] revealed enhanced precipitation of Nd-rich phases at the SiC/matrix interfaces in the QE 22 -SiC composite after T6 heat treatment and during creep (Fig. 9). Such precipitation can detrimentally affect the creep behavior in a similar way as to fiber-reinforced composites. Further, Moll et al. [11] have proposed that poor creep resistance of the QE 22-SiC composite may be explained by taking into account interfacial sliding as an additional creep mechanism... 

Figure 9. TEM micrograph showing enhanced precipitation of Nd-rich phases at the SiC/matrix interfaces in the QE 22 - SiC after T6 heat treatment and creep at 423 K.

It is common practice to add preservatives to many classes of samples, for example, nitric acid to water samples collected for metals assessment, since this minimizes adsorption to the container surface and the precipitation of insoluble oxides and hydroxides. Note however, that if water samples are to be preserved with acid, they must first be filtered, otherwise the acid is likely to solubilize metals from particulate matter included in the sample and give biased results on analysis. Nitric acid is generally preferred to hydrochloric or sulfuric acids for preservation of metal ion concentrations in water samples because these could enhance precipitation due to the low solubility of some chlorides and sulfates. Other preservatives are required for specific analytes, for example, sodium hydroxide solution to preserve cyanides. 

Clair It al (1996) reported major losses of concentrate due to the plumbing of their RO plant and observed precipitation in most samples. It was further reported that polycondensation reactions in the concentrate occurred which modified the acid-base characteristics. Phenolic compounds appeard to be lost with the permeate, but most likely, aliphatic carbon is lost. Clair it al (1996) considered the application of a cation exchange resin as a possible fractionation step. Sun it al (1995) suggested the use of a Na resin to avoid pH variation which leads to increased loss of organics in the permeate and enhances precipitation. 

Schaefer (1966) reported the activation of large numbers of ice nuclei on the addition of trace levels of iodine vapor to car exhaust (containing lead oxide nanoparticles) at temperatures from —3 to —20°C in the laboratory. The formation of lead iodide was concluded to have a seeding effect similar to that of silver iodide particles (Vonnegut, 1947), which had been used in an attempt to artificially modify cloud properties and enhance precipitation. Consequendy this method was proposed as a means to remove harmful aerosol formed in polluted urban areas, and also in artificial weather modification. However, the development of unleaded fuels, for which no similar ice nucleating ability was shown to occur in the presence of iodine (Hogan, 1967), provided a better long-term solution to this problem. 

Since shaking of protein solutions induces bubble formation, and because agitation without bubble formation (by slow stirring) causes a much slower rate of precipitation, the enhanced precipitation rate of hemoglobin S solutions was attributed to an enhanced rate of surface denaturation at the air/water-liquid interface. This idea was confirmed by direct measurements of the properties of hemoglobin films at the air/water interface with a surface balance. The surface... 

A low temperatnre (15°C) enhances precipitation and clarification, due to the decrease in Brownian movement that facilitates floccnlation of the coUoids. It is generally recommended to carry ont fining in winter. 

U.S. Environmental Protection Agency (1999). Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual, EPA 815-R-99-012, Washington, DC. 

Keywords Accidental POP release, Aftermath of war, Enhanced precipitation. Particulate matter as CCN, POP accumulation in soil, POP deposition, POP transport... 

This most likely confirms the feature that the enhanced precipitation frequency in the Belgrade area during April 1999 resulted Irom the increased number of particles in the atmosphere [23, 88], as the measuranents of the TSP concentration showed. 

Weather modification has traditionally had two components, planned and inadvertent. Planned weather modification refers to cloud seeding to increase rain or snow, decrease hail, reduce the destructiveness of hurricanes or dissipate fog. Inadvertent weather modification typically has referred to the impact of large urban cities on the local weather as evidenced by higher temperatures, altered wind circulations, increased aerosols and particles and enhanced precipitation and lightning strikes compared to surrounding rural areas. This chapter primarily will address cloud seeding, then inadvertent weather modification, and follow with a discussion of lessons these endeavors may provide in considering future climate modification. 

The other mode of failure for titanium alloys in the presence of hydrogen predominates rmder slow strain rate loading. The low strain rate embrittlement is related to hydride formation caused by strain-enhanced precipitation, but embrittlement imder impact is caused by hydride-phase formation after fabrication or heat treatment. Unlike many hydrideforming systems, titanium forms a stable hydride, but the kinetics of precipitation are slow compared to the Group Vb metals. Therefore, embrittlement is more prone to occur at low strain rates at which precipitation can proceed at a rate that is sufficient to provide a brittle crack path. 

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