Controlling Synthesis Parameters

We ve looked at how to excite our sotmd synthesis models, but there is more to the interactive control of a model than just putting energy into it. Parameters such as damping or position of excitation must also be controlled in many models. Blowing pressure or velocity for wind models is another parameter that must be controlled. Table 14.1 contains a brief list of the many physical parameters we might want to control, depending on the system and interaction. 

There are potentially many more physically/gesturally meaningfiil interactions we might want to control. If our selected synthesis model is truly physical, then these parameters might feed directly into it. If it s pseudo-physical, like parametric modal filters or PhlSEM, then the physical parameters might need to be transformed and processed first, as shown in 

Pressure on object, damping, plucking, bowing, etc., strings, plates, solids, surfaces 

Position picking, striking, bowing, or damping one-dimensional string, bar, pipe two-dimensional membrane, plate three-dimensional arbitrary objects 

Velocity picking, striking, bowing, scraping, rotating 

---

Figure 7.2 Shape-controlled synthesis of CdS nanoc stals by controlling synthesis parameters. (Reproduced from Ref [84].)...

We have reviewed the electronic properties of CNTs probed by magnetic measurements. MW- and SWCNTs can individually be produced, however, the parameters of CNTs are uncontrollable, such as diameter, length, chirality and so on, at the present stage. Since the features of CNTs may depend on the synthesis and purification methods, some different experimental observation on CNT properties has been reported. It is important, however, that most of papers have clarified metallic CNTs are actually present in both MW- and SWCNTs. The characteristic of CESR of SWCNTs is different from that on non-annealed MWCNTs, but rather similar to that on annealed multi-walled ones. The relationship of the electronic properties between SW- and MWCNTs has not yet been fully understood. The accurate control in parameter of CNTs is necessary in order to discuss more details of CNTs in future. 

The investigation of the chemical modification of dextran to determine the importance of various reaction parameters that may eventually allow the controlled synthesis of dextran-modified materials has began. The initial parameter chosen was reactant molar ratio, since this reaction variable has previously been found to greatly influence other interfacial condensations. Phase transfer catalysts, PTC s, have been successfully employed in the synthesis of various metal-containing polyethers and polyamines (for instance 26). Thus, the effect of various PTC s was also studied as a function of reactant molar ratio. 

The use of off-gas analysis, however, is a relatively expensive proposition as a means ofmonitoring/controlling extracellular parameters. It is also an indirect method and is generally used to obtain information about the synthesis of products that cannot be analyzed directly. It is possible, however, to use inexpensive phase fluorimetry-based pCD and pCCh sensors to obtain the same information. 

Exploitation of liquid-liquid microreactor in organic synthesis offers attractive advantages, including the reduction of diffusion path lengths to maximize the rate of mass transfer and reaction rates. Despite the advantages, interest in liquid-liquid micro reactors did not take off until recently, perhaps because of the complication of flow pattern manipulation combined with the limited numbers of liquid-liquid reactions. Initial interest focused on the control of parameters responsible for variation in flow patterns to engineer microemulsions or droplets. However, it was soon realized that liquid-liquid microdevices are more than just a tool for controlling flow patterns and further interest developed. 

We describe a systematic investigation of various synthesis variables that usually affect the crystallization of faujasite-type structures from Si, Al, Na, tetraethylammonium (TEA) hydrogels.A careful control of parameters such as the composition of the precursor hydrogel, temperature and crystallization time is needed to selectively prepare and stabilize pure zeolite ZSM-20 in high yield. 

ZSM-20 is a highly metastable zeolite. Its preparation necessitates the use of very specific and drastic conditions low synthesis temperatures, adequate nucleation period and a careful selection of the ingredient nature and composition. A severe and simultaneous control of all the synthesis parameters is indispensible to obtain pure ZSM-20 in high yield and reproducible conditions. 

In this work the primary pore structure of the beads was varied according to a hydrothermal treatment procedure (step 2). In order to control the secondary pore structure of the agglomerates, the primary particle size has to be adjusted. This can be carried out varying synthesis parameters (step 1) like the concentration of ammonia and water [4], the chain length of the alcohol [5] and the synthesis temperature [6],... 

For each family of silica-aluminas several synthesis parameters can be identified and applied to control the textural properties of final products. For example the role of the type and the amount of gelling agent (8,9), the solvent role (10), the silica/alumina molar ratio (9) have been discussed for MSA and ERS-8 formation. 

The synthesis procedure for mesoporous material is simple, and synthesis parameters can be controlled easily. The simple procedure does not mean that the reactions or interactions among reactants in the synthesis system are simple. Many complicated reactions, interactions, and assemblies occur in the mesoporous material synthesis system. The synthesis involves three main components Inorganic species for the formation of the inorganic wall template (surfactant in most cases) whose assembly will guide the formation of mesophase the reaction media (solvent). Figure 8.3 shows the interactions between the three main components.[59] These interactions play the key roles during synthesis. The surfactant molecules in the solution will self-assemble into a micelle or liquid-crystal phase of course, various factors can affect the assembly process,... 

SBA-15 made at low temperatures contains micropores and mesopores. The micropore volume of SBA-15 could be systematically controlled by varying synthesis parameters (some were mentioned above) for example, the synthesis temperature and the TEOS/... 

It can be concluded that weakly to moderated branched specimen (as indicated by D vcilues) with particle sizes given by Rg can be obtained by careful control of processing parameters and of ageing time. Note that the particle size can be brought into the range of the pore diameter of the y-alumina support (4 nm). Similar results are reported by Drinker et al. [42] using somewhat different synthesis parameter values. 

The mesoporous nickelsilicate membranes obtained are active and very selective to benzaldehyde and condensation products in the oxidation of styrene with hydrogen peroxide. The variation of the synthesis parameters and the pretreatment of the supports affects the permeation (Table 2) and the conversion of styrene (Fig. 7). In comparison with the conventional static reactor with a control of the H2O2 feed, the conversion of hydrocarbon on membranes after 12 h reaction was lower, but the efficiency of the H2O2 and selectivity to benzaldehyde and condensation products are higher. A variation of the pressure in the feed room favors the control of the rate of the oxidation. 

The crystal structure of zirconia and the catalytic properties of SZ generally depend on the synthesis method and thermal treatment adopted. In particular zirconia crystallises in three different polymorphs characterised by monoclinic, tetragonal and cubic symmetry. Among them only the tetragonal SZ phase displays significant catalytic properties [5-7]. Unfortunately, the synthesis of the pure tetragonal polymorph is difiBcult and, in the absence of promoted oxides [8], it could be stabilised only through an accurate control of the synthesis parameters, with particular attention to the thermal treatments. 

Preparation of Materials with Special Functions. The porosity not only defines the adsorption parameters of a material, but also its mechanical stability. On the basis of this idea and the hydrolysis and condensation kinetics and its effect on microstructure, an abrasive powder was developed (12-13) with an abrasion-controlling mechanism for human skin. The investigation of the synthesis parameter shows a direct connection between the composition and the mechanical properties of the granular material (Figure 6). As expected from the previous experiments, HCl had to be used to provide reproducible CH3 concentrations and well-defined, reproducible material properties. 

In this work, the novel polyol process was developed to support highly dispersed Pt particles on carbon support with more than 60 wt% in a single reduction step. The synthesis parameters were controlled to optimize the preparation method. Further the continuous polyol process was investigated to obtain an ultra high loading (> 75 wt %), where the reduction steps were repeated two or three times in the polyol process. Thus prepared highly dispersed Pt catalysts were applied to the cathode catalyst of DMFC. The relationship between the structure of R in the catalyst and performance of the DMFC was suggested. 

---