Stem, water flow

Two weeks after planting in the pipes, the plants were thinned to 35 pipe per pipe each and the cups to one plant each, and the treatments begun. Each first, third and fifth day of the week for twelve weeks the pipes were flushed with three liters of tap water poured in the elbow end. The water flowed past the plant root systems and drained out the screened end of the pipes into a flask. One hundred milliliter aliquots of this water ( root exudate ) were used to water the soybean plants in the cups three times weekly. After each flushing, two liters of a low nitrogen (50 ppm N) complete nutrient solution (Peter s Hydro-sol ) were added to each pipe. The soybean plants in cups were watered as needed at other times with tap water. On alternate weeks the soybean plants were fertilized with the complete nutrient solution. At 4, 8 and 12 weeks after the root exudate treatments started eighty soybean plants (10 treatments x 2 soybean varieties x 4 blocks) were randomly chosen for analysis. The soil was washed free of the plant roots and each soybean plant was divided into roots, nodules, stems, leaves and fruits. The plant parts were dried at 105°C for four days and weighed. 

Land-atmosphere exchange processes include the evaporation of soil moisture, from the leaf surface, stems, and trunks of plants, as well as transpiration, precipitation, and evaporation olf the surface of unstable water accumulations low in the ground (Figure 4.11). The water flow from the soil through the plant is the least studied link in this chain. The importance of the process of transpiration in the global water cycle cam be judged from available estimates, according to which the process of... 

In fact, membranes generally serve as the main barrier to water flow into or out of plant cells. The interstices of the cell walls provide a much easier pathway for such flow, and hollow xylem vessels present the least impediment to flow (such as up a stem). Consequently, the xylem provides a plant with tubes, or conduits, that are remarkably well suited for moving water over long distances. The region of a plant made up of cell walls and the hollow xylem vessels is often called the apoplast, as noted above (Chapter 1, Section 1.1D and in Section 9.4A). Water and the solutes that it contains can move fairly readily in the apoplast, but they must cross a membrane to enter the symplast (symplasm), the interconnected cytoplasm of the cells. 

The Liebig condenser, the coil condenser, and the double-jacketed coil condenser are similar in design and function. They are water-cooled via connection to a cold-water tap, in the case of the Liebig condenser the water flows in at the bottom and flows out at the top giving a jacket of cold water around the condenser stem and leading to a cold surface on the inside. Any volatile materials in the reaction condense on the cold outer surface and run back into the reaction mixture. The coil condenser functions in a similar way except that the cold surface is now on the inside of the condenser. This can offer an advantage in particularly humid locations because there is less tendency for atmospheric moisture to condense on the outside of the condenser and run down over the reaction vessel. The double-jacketed coil... 

The operating temperatures of the water in the main inlet and outlet tubes, the UOj in the center of the fuel rod, the water between the TFCs, and the fuel element cladding at one-half of maximum power were 26TC, 313 C, 1400 C, 280 C, and 700 C, respectively. Water flow rates in the N2 reactor primary circuit bow and stem loops were 458 and 407 tonne-h" , respectively, and the operating pressure was 180 kg-cm. ... 

When the RHRS is put in operation the primary heat exchanger and vaporizer will vvork from parallel mode to series mode. So the direction of water flow must change in the vaporizer or the primary heat exchangers, which is dependent on the temperature distribution in this sv-stem. In gemeral. if reactor is operated at high power level the direction of natural circulation will be the same as in primary heat exchanger, if reactor at low power level, the direction will be the same as in vaporizer. The experimental results indicated two circulative direction has same capacity to remove the decay heat from the core. 

Figure 12.24 shows an expaiment that demonstrates osmosis. A concentrated glucose solution is placed in an invated funnel whose mouth is sealed with a semipermeable membrane. The funnel containing the glucose solution is then placed in a beaker of pure water. As water flows from the beaker through the membrane into the funnel, the hquid level rises in the stem of the funnel. 

To operate at close to the optimum water flow rate, the operator slowly increases the amount of water just to the point where visible dust emissions abate. Due to the initial sharp increase of dust control effectiveness, the visible dust abatement point is easy to identify. Increasing water flow beyond this point does not yield any significant improvements in dust control, but will most likely cause increased bit degradation and possible seizing of the drill stem. 

There are two easy ways to grasp the soliton s pressure-head of AP = ll wt/ cm2 = lkgwt cm/cm3, by stemming from the water molecule precession velocity, V = l4m/sec. First, this AP value is derived as the kinetic energy density, namely AP=14 p V2, where p = lgr/cm3. Second, the same pressure-head is produced under gravitation by a 10 m water column, where such a column can be created by upward water flow with an initial velocity of about 14 m/sec. 

Fig. 21.5-3. Thermal effusion in water lilies. This effect apparently causes a flow of as much as 50 cm/min through the lily s hollow stems. This flow supplies the roots with oxygen.

This equation defines the flow coefficient, Cv. Here, SG is the fluid specific gravity (relative to water), pw is the density of water, and hv is the head loss across the valve. The last form of Eq. (10-29) applies only for units of Q in gpm and hv in ft. Although Eq. (10-29) is similar to the flow equation for flow meters, the flow coefficient Cv is not dimensionless, as are the flow meter discharge coefficient and the loss coefficient (Af), but has dimensions of [L3][L/M]1/2. The value of Cv is thus different for each valve and also varies with the valve opening (or stem travel) for a given valve. Values for the valve Cv are determined by the manufacturer from measurements on each valve type. Because they are not dimensionless, the values will depend upon the specific units used for the quantities in Eq. (10-29). More specifically, the normal engineering (inconsistent) units of Cv are gpm/ (psi)1/2. [If the fluid density were included in Eq. (10-29) instead of SG, the dimensions of Cv would be L2, which follows from the inclusion of the effective valve flow area in the definition of Cv]. The reference fluid for the density is water for liquids and air for gases. 

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