Precursor liquid

One of the most fascinating mechanisms for generating complex crystalline morphologies is the pathway via liquid precursors. liquid-liquid phase separation can be observed as an undesirable effect during protein crystallization from solution [133] and has been known for more than a century for CaCOs [134-136]. If such a phase is used as a precursor phase for a subsequent crystallization process, crystal morphologies with complex shape, molten appearance, and crystalline coatings can be realized. 

Such a liquid-liquid phase separation of a saturated crystallization solution can be induced with tiny amounts (pgmL range) of polyelectrolytes like PAsp or PAA in case of CaCOa. Gower et al. proposed the term polymer-induced liquid-precursor (PILP) process for the formation process of this type of precursors [137]. They can be observed as little droplets in the crystallization solution by light microscopy. Such liquid precursor droplets were independently observed with anionic dextran sulfate as additive [138]. The role of the polymer appears to be the sequestering and concentration of the calcium ions while simultaneously delaying crystal nucleation and growth to form a metastable solution. 

As the resulting crystalline products retain the shape of the precursor, non-equilibriiun morphologies can be generated (Fig. 9). The amazing spherulitic vaterite aggregates with helical extensions with spiral pits were suggested to 

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Vapors from Hquids can be put into the gas stream by bubbling the hydrogen or a carrier gas through the Hquid or by using a hot surface to vaporize the Hquid into the gas stream. Liquid precursors are generally metered onto a hot surface using a peristaltic pump and the gas handling system is kept hot to... 

Flame spray pyrolysis (FSP) a liquid precursor solution is sprayed into the flame and ignites its combustion drives the flame process. 

Urea (liquid precursor) its hydrolysis leads to NH3. This precursor is the most commonly used by car manufacturers. Liquid urea is stored in a tank and distributed upstream of the SCR system thanks to a proportioning unit. 

N3)2Ga (CH2)3NMe2 ] liquid precursor, nonpyrophoric, nonexplosive Horizontal cold-wall CVD Transparent 1 1 stoichiometric films. Growth temperature 773-1323 K, no additional N source 286... 

Figure 5.15. Gas chromatograms of liquid precursors for producing n-type Si films, namely, solution of CPS with white phosphorus dissolved at 1 wt% initial (nonirradiated) solution 20-min-, 25-min-, and 30-min-irradiated solutions and white phosphorus alone solution, for comparison, all of which were diluted with toluene before analysis. Trans-decalin was used as a standard for a quantitative estimation of an unreacted CPS monomer. [Reproduced with permission from Ref. 25. Copyright 2007 The Japan Society of Applied Physics.]...

An additional example of the flexibility of the [ ER3 2Cu(QR )2M(QR )2] architecture to direct adjustment of these precursors are the SSPs 7 and 8, which represent the first liquid single-source precursors for the deposition of CuInS2.1 An added benefit of a charge neutral liquid precursor is the potential for greater solubility in nonpolar organic solvents and the possibility of direct... 

The slurry process has been enhanced with vacuum to fabricate planar SOFCs [78], This method is of low cost and thus has been widely used to develop low-cost SOFCs. However, together with other liquid precursor methods such as sol-gel and spray pyrolysis, it is time, labor, and energy intensive because the coating-drying-sintering has to be repeated in order to avoid cracking formation. 

Silica-based materials obtained by the sol-gel process are perhaps the most promising class of functional materials capable to meet such a grand objective. In the sol-gel process liquid precursors such as silicon alkoxides are mixed and transformed into silica via hydrolytic polycondensation at room temperature. Called soft chemitry or chimie douce, this approach to the synthesis of glasses at room temperature and pressure and in biocompatible conditions (water, neutral pH) has been pioneered by Livage and Rouxel in the 1970s, and further developed by Sanchez, Avnir, Brinker and Ozin. 

Liquid precursors, in chemical vapor deposition, 22 153 Liquid products, safe storage of, 21 855-856... 

Zhou, Z., Dominey, R. N., Rolland, J. R, Maynor, B. W., Pandya, A. A. and DeSimone, J. M. 2006. Molded, high surface area polymer electrolyte membranes from cured liquid precursors. Journal of the American Chemical Society 128 12963-12972. 

Zhou, Z., Traud, R., Yadav, R., Fedkiw, P. and DeSimone, J. M. 2007. Curable, 100% solids Liquid precursors to patterned PEMs. In Advances in materials for proton exchange membrane fuel cell systems, Pacific Grove, CA, Feb. 18-21. 

Gypsum. Hydrated calcium sulfate (CaSO4-2H20). It occurs naturally and - is used as a source of sulfur, as a drying agent, an organic liquid precursor, and in polishes. 

Method //was designed for a bonded microreactor. After the channel was sealed with a Pyrex top plate using the anodic bonding technique, the liquid precursor was infiltrated into the microreactor through the outlet of the reactor under slight pressure and withdrawn. A thin film of solution remained on the walls of the microchannel. 

Process through which a network is formed from solution by a progressive change of liquid precursor(s) into a sol, to a gel, and in most cases finally to a dry network. 

Processing and Fabrication, Ceramics are traditionally prepared from powders formulated from the individual oxides however, early attempts to produce the PLZT powders by this method proved to be inadequate from the standpoint of chemical and optical uniformity. As a result, a chemical co-precipitation method designed specifically for the PLZT materials which utilized liquid precursor materials was developed and successfully implemented as a production process (15),... 

Methylene difluorocyclopropanes are relatively rare and their rearrangement chemistry has been reviewed recently [14]. In addition, electron deficient alkenes such as sesquiterpenoid methylene lactones may be competent substrates. Two crystal structures of compounds prepared in this way were reported recently [15,16]. Other relatively recent methods use dibromodifluoromethane, a relatively inexpensive and liquid precursor. Dolbier and co-workers described a simple zinc-mediated protocol [17], while Balcerzak and Jonczyk described a useful reproducible phase transfer catalysed procedure (Eq. 6) using bromo-form and dibromodifluoromethane [18]. The only problem here appears to be in separating cyclopropane products from alkene starting material (the authors recommend titration with bromine which is not particularly amenable for small scale use). Schlosser and co-workers have also described a mild ylide-based approach using dibromodifluoromethane [19] which reacts particularly well with highly nucleophilic alkenes such as enol ethers [20], and remarkably, with alkynes [21] to afford labile difluorocyclopropenes (Eq. 7). 

The manufacture of fiber reinforced composites involves the combination of the fiber reinforcement and a liquid precursor to the matrix in a mold, followed by solidification of the liquid and formation of the matrix. This solidification can be the result of chemical reac-... 

Although the reinforcing fibers may be present in the liquid precursor prior to dispensing, better properties are typically obtained when the fibers are initially present in the mold as a preform. The liquid is then dispensed into the mold such that the final matrix fills the mold and surrounds the fibers. Preforms may be arranged as mats or meshes. The fibers within the preform may be randomly oriented or may be oriented in one or more directions. 

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