Nodulation reaction

Logani and Smeltzer " have observed that, for Fe-1.5%Si at 1 000°C in CO/CO2, the initial slow reaction rate was followed by regions of linear behaviour due to the amorphous Si02 film being consumed by the growth of wustite-fayelite nodules during the early stages. These wustite-fayelite... 

Local and systemic adverse effects are associated with AIT. Patients may experience pain or subcutaneous nodules at the injection site. In patients who suffer systemic symptoms soon after the injection, the AIT plan should be assessed and may need to be advanced more gradually. Systemic reactions, including anaphylaxis, are most likely to occur during the titration phase. Patients with asthma are at higher risk for systemic and fatal reactions. Patients should be monitored for... 

Injection site reactions Enfuvirtide Onset first new doses symptoms pain, pruritus, erythema, ecchymosis, warmth, nodules, rarely injection site infection All patients Educate regarding use of sterile technique, solution at room temperature, rotation of injection sites, avoidance of sites with little subcutaneous fat or existing reactions Massaging the area vigorously before and after injection may reduce pain wear loose clothing around injection site areas take warm shower or bath prior to injection Rarely, warm compact or analgesics may be necessary... 

Trace metals are introduced to the ocean by atmospheric feUout, river runoff, and hydrothermal activity. The latter two are sources of soluble metals, which are primarily reduced species. Upon introduction into seawater, these metals react with O2 and are converted to insoluble oxides. Some of these precipitates settle to the seafloor to become part of the sediments others adsorb onto surfaces of sinking and sedimentary particles to form crusts, nodules, and thin coatings. Since reaction rates are slow, the metals can be transported considerable distances before becoming part of the sediments. In the case of the metals carried into the ocean by river runoff, a significant fraction is deposited on the outer continental shelf and slope. Hydrothermal emissions constitute most of the somce of the metals in the hydrogenous precipitates that form in the open ocean. 

The hydrogenous mode of nodule formation involves the direct precipitation of solutes from seawater via the following reactions ... 

The products are thermodynamically favored under the oxic alkaline conditions that are characteristic of most of the ocean. Reaction rates are slow, so metal oxides tend to precipitate onto detritus or preexisting nodules because of the catalytic effect of the surfaces. The Fe and Mn are supplied by both river and hydrothermal sources. For Mn, these two sources are about equal. 

Local injection site reactions The most common adverse events associated with enfuvirtide use are local injection site reactions. Manifestations may include pain and discomfort, induration, erythema, nodules and cysts, pruritus, and ecchymosis. Pneumonia An increased rate of bacterial pneumonia was observed in subjects treated with enfuvirtide in the phase 3 clinical trials compared with the control arm. Hypersensitivity reactions Hypersensitivity reactions have been associated with enfuvirtide therapy and may recur on rechallenge. Hypersensitivity reactions have included individually and in combination Rash, fever, nausea and vomiting, chills. 

Local injection site reactions including pain/discomfort, induration, erythema, nodules and cysts, pruritus, and ecchymosis were the most frequent adverse events associated with the use of enfuvirtide. 

In this case study, the selected phases are pyrite, amorphous FeS, calcite (present in limestones in the roof strata Fig. 5), dolomite (possibly also present in the limestones), siderite (which occurs as nodules in roof-strata mudstones), ankerite (present on coal cleats in the Shilbottle Seam), melanterite and potassium-jarosite (representing the hydroxysulphate minerals see Table 3), amorphous ferric hydroxide (i.e., the ochre commonly observed in these workings, forming by precipitation from ferruginous mine waters), and gypsum (a mineral known to precipitate subaqueously from mine waters with SO4 contents in excess of about 2500 mg/L at ambient groundwater temperatures in this region, and with which most of the mine waters in the district are known to be in equilibrium). In addition, sorption reactions were included in some of the simulations, to contribute to the mole transfer balances for Ca, Na, and Fe. 

Stars with high arm numbers are commonly prepared by the arm-first method. This procedure involves the synthesis of living precursor arms which are then used to initiate the polymerization of a small amount of a difunctional monomer, i.e., for linking. The difunctional monomer produces a crosslinked microgel (nodule), the core for the arms. The number of arms is a complex function of reaction variables. The arm-first method has been widely used in anionic [3-6,32-34], cationic [35-40], and group transfer polymerizations [41] to prepare star polymers having varying arm numbers and compositions. 

In the composition range where the nodular morphology was shown, because the matrix (PEI phase) contained relatively small amount of epoxy, the temperature effect on the viscosity was larger than the reaction effect. Thus, the viscosity of the PEI matrix in the nodular morphology became reduced as the cure temperature was increased, which made epoxy nodules coalesce more easily with each other. As the cure temperature is increased, the viscosity of the PEI-rich matrix decreases from 210 Pa.s at 150°C to 50 Pa.s at 190°C. 

Figure 7 illustrates the influence of the increase in the DVB/RLi ratio as well as reaction time for polybutadienyllithium anions. The efficiency is plotted as the ratio of linked to unlinked chains. At the very high ratios (11.9-12.9) nearly quantitative linking is observed as seen from the G.P.C. analysis in Figure 8. However, the moelcular weight distribution is broadened at the higher ratios, possibly indicating intermolecular or inter-nodule star coupling between two different star macromolecules. As mentioned previously, Reaction 5 would be more likely to occur at the higher ratios thus the overlap of the...

The reaction temperature was also found to influence the efficiency of the linking reaction. As summarized in Table I, the increase in reaction temperature from 25°C to 45°C resulted in an increase in star-branch polymer formation. Qualitatively, it was also observed that the formation of vinylbenzylanion occurred more rapidly at the elevated temperatures. Apparently, the increased reaction temperatures render the intermolecular attack on the pendant vinyl groups by the polydienyllithium anions more favorable in comparison to the intramolecular intra-nodule alkylbenzyl anion-vinyl group reaction (Table I on the following page). 

In comparison to the polybutadiene stars under similar reaction conditions, the polyisoprene stars showed slightly lower degrees of branching. The added steric hindrance from the methyl group on the polyisoprene anion perhaps makes entry into the DVB "microgel" nodule difficult. 

---