Plants solute penetration into

Difficulty in Translocating Brassinolide through Plant Tissue. The navel orange experiments revealed that brassinolide was only effective when polyethyleneglycol was added to the spray solution to prevent quick evaporation. Brassinosteroid is active at very low concentrations, such as 0.1 ppm. When such a low concentration was sprayed in solution on the plants with surfactant, the solution dried up immediately and did not be penetrated into the plant tissue. Thus, addition of chemicals to avoid quick evaporation is necessary for a successful treatment. 

According to Vedernikov (5), the hydrolysis of pentosans and dehydration of pentoses in a one-step furfural production from a plant raw material in the presence of small amounts of concentrated catalyst solutions are accelerated differently by acetic and sulfuric acid (or other strong catalysts). Due to the marked chemosorption heat, the molecules of sulfuric acid sorbed on the surface of the particles are bound tightly to the polysaccharides by chemosorption and do not penetrate into the particles. The strength of the chemosorption between the molecules of sulfuric acid and polysaccharides increases with an increase in the initial acid concentration. It is minor for dilute solutions. As small amounts of sulfuric acid are used (2-4% of material mass), it covers less than 1% of the entire surface of particles. 

In this technique, the fiber swells and the type of the alkaline treatment and the concentration influence the degree of swelling and thus the degree of lattice transformation. It is reported that Na" has got a favorable diameter and is able to widen the smallest pores in between the lattice planes and able to penetrate into them. Therefore, sodium hydroxide (NaOH) treatment results in a higher amount of swelling. The alkali solution is reported to influence not only the cellulosic components inside the plant fiber but also the noncellulosic components (hemicellulose, lignin, and pectin) [69]. 

Extraction is a process in which the solvent penetrates the dried herb and dissolves the soluble components of the plant material. These then diffuse out into the free solvent surrounding the plant material particles. This process eventually reaches a state of equilibrium (Theoretically, complete equilibrium is only achieved at infinite time and the approach to completion is an asymptotic curve Figure 12.4.) In practice, about 90% of available solids come into solution within 24 horn s for a typical leaf herb at ambient temperature, although harder material, such as some dried woody roots and barks, will take rather longer to achieve a satisfactory degree of extraction. 

Ecdysteroids are generally regarded as not being able to penetrate insect cuticle readily [179], However, the rice stem borer, C. suppressalis, has a thin cuticle which allows ecdysteroids to penetrate when ligated last instar larvae are dipped into a methanolic solution of the test compound for 5 s [180], The proportion of pupated abdomina are assessed after 48 h. This assay is less sensitive than the Calliphora bioassay, but is easier to perform. Its main application has been in screening plant extracts for the presence of phytoecdysteroids [74],... 

The plasma membrane is a major barrier to the diffusion of solutes into and out of plant cells, the organelle membranes play an analogous role for the various subcellular compartments, and the tonoplast performs this function for the central vacuole. For instance, although H20 and C02 readily penetrate the plasma membrane, ATP and metabolic intermediates usually do not diffuse across it easily. Before we mathematically describe the penetration of membranes by solutes, we will briefly review certain features of the structure of membranes. 

Although some report that antibodies are able to penetrate cell walls fully, immunofluorescence micrographs of cell-wall protein localizations suggest that this is not the case (21). Antibody solutions infiltrated under vacuum into stem tissues do not appear to reach inner surfaces of the cell walls, whereas antibodies applied to cut surfaces of the stem clearly do (see Fig. 3 in ref 21). In order to facilitate the penetration of antibodies into plant cells, the cell walls need either to be opened or removed. This is most often accomplished by digestion with the enzymes cellulase and/or pectinase (22). 

To determine reliable model parameters, a minimum of three injection experiments with tracers and one tracer experiment for each solute of interest should be carried out. The evaluation of these experiments is sketched in Figure 6.11, together with the symbols of the measured first moments. The injected signal is assumed to be a rectangular pulse. The first tracer experiment detects the dead time of the plant while the column is replaced by a zero-volume connector. The other experiments are carried out vfith the column in place, using a tracer that cannot get into the pores (Tracer 1) and another one that penetrates the pores (Tracer 2). These experiments are necessary to determine the dead times to.mt and to. Finally, a solute peak is analyzed, but it has to be noted that meaningful results... 

Leaves of pin oak showed a different sequence of steps in leaf injury from that seen in other plant species. Initially, injury began with collapse of adaxial epidermal cells. Initial lesions consisted of approximately one to six collapsed epidermal cells which resulted in a slight depression on the leaf surface. At this stage, all cells in the mesophyll layers, and the abaxial epidermis were unaffected. After several more simulated acid rainfalls larger lesions, with increased surface area and depth, developed from smaller lesions. These lesions encompassed five to fifteen collapsed epidermal cells. Penetration of acidic solutions into the mesophyll tissues resulted in collapse of epidermal and underlying palisade parenchyma cells. 

Chemical plants are designed and constructed with a variety of metals, alloys, and nonmetallic materials such as plastics. The nature and mechanism of degradation of these materials differ. Corrosion of metals and alloys in aqueous media occurs by electrochemical mechanisms, whereas the degradation of a plastic is by the penetration of chemicals into its matrix. Nevertheless, the term corrosion is used liberally to describe the oxidation of metals in aqueous solutions or gas phases and the deterioration of plastics by chemical attack. 

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