Diameter control

Diameter control. Parameter 6, is important to the final quality of the obtained crystal. The sides of the crystal need to be straight because they reflect the regularity of the lattice planes within the crystal. Effects of deviation from "correct growing conditions on the quality of the crystal so-produced are shown in the following diagram, given as 6.4.8. on the next page. 

Cui, Y. Lauhon, L. I Gudiksen, M. S. Wang, J. Lieber, C. M. 2001. Diameter-controlled synthesis of single-crystal silicon nanowires. Appl. Phys. Lett. 78 2214-2216. 

The number average diameter of microspheres obtained from polymers synthesized, by emulsification of polymer solutions followed by solvent extraction and/or solvent evaporation methods, can be controlled by choosing the appropriate conditions at which particles are produced. However, by this method particles with 15 p,m and with D D > 1.9 are produced. Spray drying did not provide poly(L-Lc) particles with regular spherical shape. Direct synthesis of poly(L-Lc) microspheres by ring-opening polymerization with stepwise monomer addition can be used as a method of choice for the production of microspheres with diameters controlled to ca. 6 p.m and with diameter polydispersity parameter < 1.20. 

Figurel. l29Xe NMR chemical shifts 6 (filled symbols) and 1/6 (open symbols) as a function of pore diameter. = controlled pore glasses, 75-385A - = ZSM-12 = ALPO-11 A = clathrasil D3C =clathrate hydrates.

Process Stability and Control. Operationally, automatic control of the crystal radius by varying either the input power to the heater or the crystal pull rate has been necessary for the reproducible growth of crystals with constant radius. Techniques for automatic diameter control have been used since the establishment of Czochralski growth. Optical imaging of the crystal or direct measurement of the crystal weight has been used to determine the instantaneous radius. Hurle (156) reviewed the techniques currently used for sensing the radius. Bardsley et al. (157,158) described control based on the measurement of the crystal weight. 

Many methods have also been demonstrated to process materials other than polystyrene and silica into spherical colloids as monodisperse samples. For example, a new method was recently reported that allowed for the generation of titania spherical colloids with uniform diameters controllable in the range of 200 to 500 nm.66 Titania is a semiconductor and has a much higher refractive index (2.6 for anatase and 2.9 for rutile) when... 

Laser ablation (PLV) Ablation from graphite doped with (Fe, Co, Ni,...) catalyst 1.4 (1-1.8) High quality, good diameter control, bundled tubes commercial... 

The inverse-micelle approach may also offer a generalized scheme for the preparation of monodisperse metal-oxide nanoparticles. The reported materials are ferroelectric oxides and, thus, stray from our emphasis on optically active semiconductor NQDs. Nevertheless, the method demonstrates an intriguing and useful approach the combination of sol-gel techniques with inverse-micelle nanoparticle synthesis (with OTO erafe-temperature nucleation and growth). Monodisperse barium titanate, BaTiOs, nanocrystals, with diameters controlled in the range from 6-12nm, were prepared. In addition, proof-of-principle preparations were successfully conducted for Ti02 and PbTiOs. Single-source alkoxide precmsors are used to ensure proper stoichiometry in the preparation of complex oxides (e.g. bimetallic oxides) and are commercially available for a variety of systems. The... 

The diameter of the compression roller and punch head geometry can both affect tablet manufacturing performance. The compression roller diameter controls the rate and... 

Figure 4. Schematic diameter control system. (After Ref. 1.)...

The motivation for the study of nanomaterials stems from the expected size effects SiNWs are no exception. This makes the issue of diameter control very important. In a previous section we have shown that the growth temperature affects the diameter of the SiNWs grown by the metal catalyst VLS method but not the diameter of SiNWs grown by the OAG method. Here we show that the SiNW diameter can be affected by the carrier gas used in the growth process. 

ASTM Designation El 055 Standard Specification for Electrofusion Type Polyethylene Fittings for Outside Diameter Controlled Polyethylene Pipe and Tubing ... 

For CVD-VLS nanowire growth, colloidal particles are first size-selected in solution and then drop cast or spun cast onto the substrate prior to nanowire deposition. Nanowire diameter control is very important, as the optical, electronic, and mechanical properties of nanowire depend on the nanowire diameter. The histograms shown in Fig. 5B illustrate that the nanowire diameter... 

Polymer growth is initiated at the core molecule diameter controlled by growth control. 

Kataura H, Kumuzawa Y, Maniwa Y, Ohtsuka Y, Sen R, Suzuki S, Achiba Y (2000) Diameter control of single-walled carbon nanotubes. Carbon 38(11-12) 1691-1697... 

Microsuspension and Inverse-microsuspension. In suspension polymerizations, particle formation occurs through a droplet breakup-coalescence mechanism, with the diameter controlled by the temperature, interfacial tension, agitation intensity and conversion. Suspension polymerizations have typically been characterized by an initiator soluble in the monomer phase and particle diameters in the 50-1000 pm range [40]. Smaller particles (0.2-20 pm) have been produced at higher agitation speeds (lower interfadal tensions) [41] and in such cases a prefix micro has been added to the nomenclature (microsuspension) to reflect both the dominant synthesis conditions (suspension) and the nominal particle size (1 micron). Therefore, microsuspension polymerization has historically referred to a subdomain of suspension polymerization occurring at smaller particle sizes. Based on an analogy to this nomenclature, inverse-microsuspension polymerization has been proposed for similar water-in-oil... 

Gas chromatographic research with plasma-coated silica gel adsorbent and an ultrafiltration test of organic solutes having different molecular sizes have revealed that the polymer appears to have micropores of 2-4 nm in diameter. Control of the dissolution rate of pharmaceuticals by dianging the polymer film thickness was also attempted [72], It was found that propargyl alcohol is a very promising monomer and a few applications of this hydrophilic plasma polymer have been reported [72]. 

FIGURE 5.16 Enthalpy recovery results for o-terphenyl aged at Tj — 11°C in (a) bulk state and (b) confined in an 11.6-nm pore diameter controlled pore glass material showing much smaller buildup of enthalpy overshoot upon aging of the confined material. Originally, similar data were interpreted [McKenna et al. [1992] to imply reduced aging in confined systems. (Data from Simon et al. [2002].)... 

Drill pipe sections that are coupled into a drill string are typically of the oil field type, that is, 127 mm in diameter, according to the American Petroleum standards. This pipe has a 100- to 108-mm inside diameter at the pipe or tool joints. This diameter controls the type of carrier tools, samplers, and sensors that can be used for geotechnical purposes. The bottom few sections of drill pipe typically are composed of a heavy thick-walled drill... 

For many applications a precise diameter control is required. Fiber dimensions and morphology depend strongly on process parameters such as pol5mier properties molar mass, molar mass distribution, glass transition temperature, and solubility solution properties such as viscosity, viscoelasticity, dielectric constant, concentration, surface tension, electrical conductivity, and vapor pressure and ambient conditions such as humidity and temperature. 

El-evation of the reactors to facilitate refuelling frcm the underside althou having tenperature benefits for charge route ccsrponents has resulted in the only access to the reactor.outlet plenium for inspection purposes being by way of 7" diameter control rod stanc ipes. 

Cui Y Lauhon LJ, Gudiksen MS, Wang J, Lieber CM. Diameter-controlled synthesis of single-crystal sihcon nanowires. Appl Phys Lett 2001 78 2214. 

Cheung CL, Kurtz A, Park H, Lieber CM. Diameter-controlled synthesis of carbon nanotubes. J Phys Chem B 2002 106 2429-33. 

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