Nodule size

Ambrosia elatir, Euphorbia leachates of phenolic red d nodule size no. red d ... 

If mycorrhizae are sites of action for allelochemicals, this is an important indirect aspect of allelopathic interaction among plants. Inhibition of mycorrhizal formation or a reduction in the efficiency of mycorrhizal association would reduce the nutrient level of the mycorrhizal plant and subsequently its competitiveness, stress tolerance or nodulation. Although allelochemicals have been implicated in the reduction of nodulation and nodule size, possible mycorrhizal involvement has not been examined. This is a difficult area of research but one that will provide better understanding of this complex situation. 

Figure 4. Gray-scale synchrotron-based micro-X-ray radiation fluorescence (pSXRF) maps in negative contrast showing the distribution of some elements in a soil nodule from the Morvan region, France (Baize and Chretien 1994 Latrille et al. 2001 Manceau et al. 2002b). All maps except Fb were obtained by scanning the soil nodule under a monochromatic beam with an energy of 12,985 eV (Pb L3-edge - 50 eV). The Pb map was obtained by subtraction of the normalized maps taken 50 eV above and below the Pb Le-edge to eliminate the contribution from As. Nodule size 3 x 3.5 mm, beam size 16 pm H x 6 pm V step size 16 x 16 pm dwell time 250 ms/point. Data were recorded on beamline 10.3.2 at the ALS (Beikeley).

Thyroid ultrasound is very helpful in determining the nodule size, number, type, and whether the nodule is cystic or solid. 

Nodule size greater than 25-mm diameter Requires longer burning time or higher burning temperature (Heilmann, 1952)... 

NC-AFM is better than C-AFM for imaging small pores such as those in ultrafiltration and nanofiltration membranes. The reason for this is that the diameter of the cantilever tip apex is greater than the pore diameter. When the tip is passed over the small pore, the tip cannot penetrate into the pore, and there will not be a great change in cantilever deflection. However, TM-AFM is more successful at measiuing the pore size and nodule size on the membrane surface. 

Table 4.11. Data on nodule size and roughness parameter at the internal and external surfaces of three PSf hemodialysis hollow fiber membranes manufactured by Baxter, Fresenius, and Membrana...

Kim et al. discussed surface structure and the phase separation mechaiusm of polysulfone membranes by AFM [43]. A membrane formed by immersion in a pure water coagulation bath showed a nodular structure with a nodule size of about 25 nm, which was believed to be the result of spinodal decomposition. A membrane formed by immersion in a coagulation bath mixture (water/NMP 20/80 by weight) had the porous structure with a mean radius of 146 nm, which was the result of nucleation and growth of the polymer-poor phase. 

Broadhead and Tresco studied the effects of fabrication conditions on the structures and performances of membranes formed from poly(acrylonitrile-vinylchloride) (PAN-PVC) by using the phase inversion process [85]. They reported the relationship of the fine-surface structure of PAN-PVC membranes to the membrane performance and membrane fabrication method. The fine-surface structure of nodular elements and the size of these elements could be altered by changing the precipitation conditions. Membranes were prepared at 22 on 55 mm diameter polished silicon wafers by spinning at 1500 rpm for 20 s with a spin coater [86]. The film was immediately precipitated in one of the four different precipitation media. The first three media consisted of deionized water at 4,22, and 54 °C. These membranes were referred to as Type 1 , Type 2 , and Type 3 , respectively. The fourth medium was a 50/50 mixture of deionized water and N,iV-dimethylformamide (DMF) at 54 °C and coded as Type 4 . Figure 4.53 shows the histograms of the nodule size distributions observed at the skinned surface of the membranes made under four different precipitation conditions. The sizes of these nodular elements became smaller and more uniform with milder precipitation conditions, which supports the theory that nodules are formed through spinodal decomposition under these conditions. In addition, the size of these nodules could be related to water permeability. Hence, water transport occurred through the interstitial spaces where the pores could be situated. 

Fig. 4.53a-d. Histograms of the nodule size distribution observed at the skinned surface of membranes made under different precipitation conditions aType 1, bType 2,cType 3, and d Type4. Please note the shift in size and dispersiveness of the nodular elements. Reprinted from [85]. Copyright 1998, with kind permission from Elsevier... 

There seems to be no relationship between the membrane application and the nodule size. 

Material Application Pore size or MWCO (Da) Nodule size Roughness (nm) Reference ... 

Khulbe et al. [4] also measured the nodule sizes (the average of at least 20 measurements) at the inner surface, at the areas near the inner surface, in the middle section and near the outer surface, and at the outer surface for hollow fibers fabricated at different air gaps. Table 6.1 summarizes the results. 

Table 6.1. Average nodule size at the inner and outer surfaces and in the cross section near the inner surface, middle section, and near the outer surface of UF poly(etherimide) hollow fibers for different air gaps...

The nodule sizes are similar to those measured by Fuji et al. [13]. 

The nodule sizes at the inner surface and near the inner surface are similar. There is no signihcant effect of air gap on the nodule sizes observed in this region. 

The nodules in the middle section are larger than the other regions. The nodule sizes in the middle section increase as the air gap increases. 

The nodule sizes at the area near the outer surface and at the outer surface are similar. The nodule sizes in this region decrease with an increase in air gap. 

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