Search Results

Sorption is a key factor that influences a pesticide’s environmental fate and biological activities (Villaverde et al. , 2008 ; Wang & Keller, 2009 ; Kravvariti et al. , 2010 ). Sorption may involve both adsorption processes representing uptake of molecules onto the outer surfaces of soil

In: Nematology

Study of interaction of NO and (NO)2 molecules with silver clusters has been carried out using the hybrid method S2LYP based on density functional theory (DFT). The role of cluster charge and site of adsorption on N–O stretch frequency, adsorption energy and geometry has been investigated. Four cluster models of different size have been used for simulation of (NO)2 adsorption on Ag{111} surface. The pronounced effect of N–N bond shortening in comparison with gaseous (NO)2 has been found due to adsorption of (NO)2 on silver cluster. This phenomenon is important as possible pathway of N–N bond formation in catalytic fragmentation of NO molecule. The calculations showed that the silver octamer is the best candidate for simulation of formation and fragmentation of (NO)2 on Ag{111} surface within the cluster model.

In: Computing Letters
This journal has been acquired by Taylor & Francis. For more information, please click here.

 Click on title to see all prices

Clustering of water molecules on model soot particles is studied by means of quantum calculations based on the ONIOM approach. The soot particles are modeled by anchoring OH or COOH groups on the face side or on the edges of a graphite crystallite of nanometer size. The quantum calculations aim at characterizing the adsorption properties (structure and adsorption energy) of small water aggregates containing up to 5 water molecules, in order to better understand at a molecular level the role of these OH and COOH groups on the behavior with respect to water adsorption of graphite surface modelling soot emitted by aircraft.

In: Computing Letters

(lead, cobalt, cadmium, chromium, nickel, zinc and copper) in the urban environment (Almaty) by going through the process of adsorption of toxic substances from exhaust gases of vehicles, industrial plants, dust and vapors from the air. Due to this, the improvement of the environment takes place, i.e. a

In: Israel Journal of Ecology and Evolution

Fragrances (volatiles) from whole flowers, petals, sepals plus gynoecium, anthers, and pollen were collected from Rosa rugosa Thunb. by headspace adsorption methods and analyzed by gas chromatography/mass spectrometry. Each flower part showed a distinctive volatile profile. Petal volatiles, dominated by terpenoid and benzenoid alcohols, contributed most to the whole-flower fragrance. Sepal odors contained mainly sesquiterpenes, together with several compounds found in the petals. The major volatiles in the androecium were more diverse and overall different from the perianth. Empty anthers shared a high proportion of their volatile profile with pollen. Pollen odor appeared to be self-contained, showing only minor adsorption of volatiles from sepals and petals. Compounds typical of the androecium were present as significant, albeit quantitatively small, components of the whole-flower fragrance, where they may well function as signals to pollen-seeking insects.

In: Israel Journal of Plant Sciences

A small complex area in the Samarian Desert was investigated. The rainfall reaches about 250 mm. The area consists of a hill where limestone, chalks, marls and nari crust are exposed. Various young sediments are also present. Mediterranean batha vegetation characterizes the Terra rossa and dark Rendzina soils that cover hard rocks on northern and western slopes. Irano-Turanian vegetation (mainly Noaea mucronata) covers the Rendzinic Desert Lithosol that has developed from hard chalk on the southern slopes. At the same exposure Saharo-Arabian vegetation (mainly Fagonia mollis and Blepharis ciliaris) characterizes the soft chalk that is covered by calcareous desert Lithosols. Almost no vegetation was found on marl with a marly desert Lithosol soil cover; only toward the margins is there some cover of Salsola vermiculata. The vegetation on natric Grumic Serozems that developed from clay sediments is restricted to favored spots, like hollows, cracks etc., that receive higher amounts of water. These spots are also relatively leached. A close relationship was found between vegetation characteristics and degree of soil leaching: vegetation diversity and density decrease with the increase of the Exchangeable Sodium Percentage, Sodium Adsorption Ratio and salinity (Electrical Conductivity) values. The same is true with respect to lime content of soils on hard rocks. The reason for these relationships is attributed to different moisture regimes.

In: Israel Journal of Plant Sciences

Zinc uptake in the upper (leaves) and lower ground parts (roots, stems, rhizoids) of Halophila stipulacea (Forsk.) Aschers, and leaf cell mortality were examined in laboratory experiments. The seagrass was incubated for 12 days in zinc concentrations between 10−4 and 10−7 M. At 10−6 and 10−7 M Zn concentrations, uptake was characterized by a rapid initial adsorption rate slowly decreasing up to the 4th day, after which an equilibrium was reached; the ‘equilibrium’ concentrations increased as the Zn in sea water increased. At the higher Zn concentrations (10−5 and 10−4M)the content in the plant continued to increase after the 4th day, perhaps due to the development of necrotic effects mainly evident in the teeth and epidermal cells as well as in the mesophyll cells of the leaves. A positive correlation between Zn content in the upper and lower parts of H. stipulacea was also found, whereas Zn uptake in leaves was significantly higher than in the root-rhizomes-rhizoids. It was also demonstrated that some zinc can leak from the tissues of this seagrass.

In: Israel Journal of Plant Sciences
Author: Guy J. Levy

The differences between the characteristics of treated wastewater (TWW) and those of its fresh water of origin, coupled with the increased necessity to use TWW for irrigation, particularly in arid and semiarid regions, present the farming community with unique and unfamiliar problems, among which is the possible degradation of soil structure and stability. Probable risks for adverse changes in the structure and stability of soils and their hydraulic properties following irrigation with TWW may stem from the higher levels of dissolved organic matter, suspended solids, sodium adsorption ratio (SAR), and salinity in the TWW compared with its fresh water of origin. Laboratory studies with specimen clays have indicated that irrigation with TWW can lead to conditions in the soil that enhance clay swelling and dispersion. These phenomena can, in turn, initiate and/or increase clay depletion from the upper soil layer and the deterioration in aggregate stability; decrease soil hydraulic conductivity; and increase soil susceptibility to seal formation, runoff, and soil erosion. These possible scenarios are expected to occur mostly in winter when the soil is exposed to rainwater (i.e., water without electrolytes), which tends to enhance the sensitivity of the soil clays to swelling and dispersion. The current review is limited to Israeli studies from the past 15 years, because in studies prior to this period most of the TWW used for irrigation was of extremely poor quality. The impact of irrigation with TWW on a number of soil determinants that are closely related to soil-structure stability (e.g., clay movement and illuviation at deeper soil layers, aggregate stability, saturated hydraulic conductivity, and the generation of runoff and soil loss) is presented. Results from the examined studies suggest that the effects of irrigation with TWW are inconsistent and complex. The results seem to depend, beyond variation in the quality of the TWW, on soil properties (e.g., texture, lime content) and conditions prevailing in the field (e.g., type of tillage, rate of wetting, etc.). It is recommended that caution be exercised when TWW is used for irrigation of cultivated land and that indices representing soil-structure stability be closely monitored to ensure sustainability of that structure.

In: Israel Journal of Plant Sciences
Author: Kiyotaka Sakai

) and plasma adsorption (PA). Clearance, which is the fractional reduction in the blood concentration of a waste product multiplied by the blood flow rate through the dialyzer, is a term used to signify that portion of the blood supplied to a dialyzer, filtration device, kidneys or other blood

In: Frontiers of Medical and Biological Engineering