Teflon sphere

Goudonnet J.P., Begun G.M., Arakawa E.T., Surface-enhanced Raman-scattering on silver-coated Teflon sphere substrates, Chem. Phys. Lett. 1982 92 197-201. 

The heat of solution of tripropylamine and of dipropylamine in HF was determined by using the same cell with some slight modifications. Instead of using the sample capsule, the amine was introduced in the empty lower trough which was then closed with a Teflon sphere. Afterwards, the HF was poured into the volume above the sphere. A thin Voltalef grease layer on the sphere ensured a tight seal. 

Irradiance Biospherical Instruments, Inc./QSP-170 Teflon sphere collector-silicon photovoltaic detector 6% Measures only photosyn-thetically active light... 

Before TERS was considered, scanning near-held optical microscopy (SNOM) in combination with SERS was used to perform high-resolution structural DNA analysis [73]. In those experiments, brilliant cresyl blue (BCB)-labeled DNA was adsorbed on silver-coated Teflon spheres in order to examine the correlation between topography and near-held Raman spectra. 

Figure 1. Diagram of Teflon cell (1) platinum electrode (2) glass scintillator (3) Macor ceramic disk cell bottom (H) Teflon O-ring (5) flexible elbow (see insert) (6) cell ports (six of them around cell body) (7) light pipe. Inset shows the details of the flexible elbow (8) stainless steel sphere (9) concave Teflon spacer (10) platinum wire for electrical connection across elbow (11) lock nut.

The treatment of C q with an excess of bis(trifluoromethyl)nitroxide [(CF3)2NO radicals] leads to multiple additions with an average of 18 (Cp3)2NO groups bound to the fuUerene sphere (Scheme 6.16) [74]. The reaction has been carried out in a glass tube equipped with a Teflon valve. The resulting light brown solid decomposes above 158 °C. 

Synthesis of Acid-Prepared Mesoporous Spheres (APMS).3 Tetraethylorthosilicate (TEOS, 5.65 g, 27.1 mmol) was added to a solution of cetyltrimethylammonium bromide (CTAB, 1.20 g, 3.30 mmol) in aqueous acid (4.40 g cone. HC1, 55.5 g H20). This mixture was stirred for 1 hour and then transferred to a teflon-lined Parr autoclave and heated at 150 °C for 40 minutes. The mixture was cooled and filtered to recover a white powder. APMS could also be prepared at temperatures between 80 and 230 °C by adjusting the heating time (lower temperatures, longer times). 

The preparation of rough silver films by vapor deposition results in reproducible and stable surfaces for SERS. For example, deposition of 20-nm Ag films onto Teflon, polystyrene, or latex spheres [29,30] has been performed. These substrates produced strong SERS intensities for various organic adsorbates and good reproducibility between multiple rims. However, vapor deposition can be slow and needs access to a vacuum system. There are also some variables that need to be controlled, such as the film thickness, deposition temperature, and use of annealing procedures. Moreover, unless the experiment is performed under vacuum, the film is exposed to the atmosphere after deposition. Even a brief exposure to the atmosphere results in contamination of the surface and the formation of an inactive oxide layer. 

The materials used in the different size vessels are based on stainless steel or aluminium alloys, but also on polymeric materials, such as Teflon. The sphere form is ideal for the minimization of vapour release, due to its minimum surface to volume ratio with respect to all other possible geometries, and for the limitation of stress and uniformity of strain distribution. On the other hand, the manufacturing costs for spheres are too high, in compared with cylindrical shape which is the most economical solution. 

The 1H NMR spectra were obtained at 100 MHz using Nafion spheres approximately 6.5 mm in diameter that were held between two Teflon vortex plugs in a 12-mm tube. The spheres were centered in the rf coil and were covered with benzene-d6. 

Fig. 6.9-29 Teflon cylinder with hemispherical ends, mounted in a reciprocating shaker, and used to form small spheres by the spherical agglomeration process B.73, B.97]... 

Estimate the free energy of attraction between two spheres of radius 500 nm at separation distances of 1,10, and 100 nm for the following systems (a) water-air-water (b) pentane-water-pentane (c) hexadecane-water-hexadecane (d) quartz-air-quartz (e) quartz-air-hexadecane and (f) Teflon-water-Teflon. 

The force of interaction between a Teflon AF1600 coated micron-sized colloidal sphere and a Teflon AF1600 coated flat plate was meastrred using atomic force microscopy... 

To determine experimentally the function in Eq. (5.64), first-year engineers at Cornell observed spheres of various materials (steel, brass, aluminum, glass, lucite, nylon, teflon, and polypropylene) falling through various fluids (water, vegetable oil. 

Computing the sphere density as a separate quantity allows one to scan for errors - errors in the formula for density and errors in the data. Check the nylon spheres - all should have about the same density, about 1,120 kg/m. Teflon should be about 2,300 kg/m, steel about 7,700 kg/m, polypropylene about 840 kg/m, and so on. 

For the first type, glass spheres having a size range of 5 - lOy were used (Microbeads Division, Cataphote Corporation, Jackson, Mississippi). These were added to an approximately 3% solution of the rubber in benzene, mixed, and cast into films of about 0.5 mm thickness on a teflon pan. After evaporating the benzene at room temperature, these were dried for about 16 hours in an oven at 45 C, then transferred to a press where they were cured by heating at 90 C for 20 minutes and then heated to 140 C for 40 minutes under 3000 psi pressure. 

The CS spheres were obtained from a hydrothermal treatment of sucrose (table sugar) according to a modified hterature procedure. A IM aqueous solution of sncrose in demineralised water was placed in a Teflon-lined autoclave. The solution was kept at 160°C for 4h. Afterwards the solid product was separated by centrifugation and was washed with a mixture of ethanol, acetone and demineralised water until a colorless solution was obtained. The resulting black powder was dried at room temperature in vacuo to constant weight. 

---