Types of Nanoshells
It is possible to obtain nanoshells by a variety of methods. Given an application and size, one can select a method of synthesis. But most of these methods have the disadvantage of non-uniform coating which limits their applications. Hence it is very important to decide on the method of synthesis as it is difficult to obtain controlled and uniform coating. The preferred method involves surface precipitation of inorganic molecular precursors on particles and removal of the core by thermal or...
Some Unusual Properties
In this section, are briefly summarized some of the fascinating discoveries in this area. C60 shows anomalous solubility behavior. Normal solutes show a linear temperature dependence of solubility. In most cases, the solubility increases upon warming. In inorganic systems, unusual phenomena are seen due to solute-solvent interactions. Studies of solubility of C60, studied in a number of solvents, indicate that there is a solubility maximum at near room temperature Ref. 118 280 K , dissolution...
Synthesis and Purification of Fullerenes
For a synthesis of fullerenes, all that is needed is a welding transformer, a chamber connected to a vacuum pump even a single stage oil sealed rotary pump is adequate and some graphite rods. The graphite electrodes are brought into close contact with each other and an arc is struck in an atmosphere of 100 200 Torr of helium or argon. To sustain the arc, a voltage of 20 V ac or dc may be necessary. For a graphite rod of 6 mm in diameter, about 50 200 A current may be consumed. Generally,...
Electrochemistry
The shells in core-shell nanoparticles are porous and hence permit electron transport through them. Ag ZrO2 shows a characteristic anodic peak at 0.310 V and a cathodic peak at 0.120 V in the solution phase containing 0.1M tetrabutyl ammonium hexafluorophosphate TBAHFP CH3CN on the Pt electrode surface Ref. 45 . The redox couple is centered at E1 2 0.215 V vs. Ag AgCl with a peak separation of 0.190 V at 25 C for the anodic curve trace a in Fig. 9.11 A . The sharp and symmetrical anodic peak at...
Nanoshells from Liposomes
Another method followed for the synthesis of silica nanoshells involves the use ofliposomes as the templates. It was found that liposomes which are covered with silica are nonporous in nature. Hence, the exact properties of the lipid system are retained. This is important as liposomes are very sensitive to parameters such as pH and ionic strength, and also to the presence of organic solvents in the reaction mixture. Hence this kind of a system can find use in the case of drug delivery mainly...
Superlubricity
Hirano and Shinjo Ref. 11 in 1990 showed the origin of the ultra low friction of graphite between two incommensurable having an incommensurate contact geometry, which prevents collective slip-stick motion of all atoms in that contact graphite layers rotated with respect to each other. Since then, many research groups have used the Frictional Force Microscope to study this further. Recently, Martin Dienwiebel, et al. Refs 12, 13 have revealed that when two parallel surfaces slide over each other...
Nanotechnology in Diagnostic Applications
Research efforts are also being driven in the direction of using nanotechnology for molecular diagnostic purposes such as biological research, clinical diagnostics, detection of biomolecules and drug discovery. The focus of this section is on understanding the use of nanosystems for clinical diagnostics, especially in the early diagnosis of various forms of cancer. The main drawback of the laboratory tests currently used for the detection of cancer is that they try to identify visible changes...
References Tyf
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Shipway N. E. Katz And I. Willner Chemphyschem 1 2000
1. Atomic and Nano Technology, IBM Research, http www.research.ibm.com atomic. 2. Langmuir, I.,J. Am. Chem. Soc., 39 1917 , p. 1848. 3. Blodgett, K.J. Am. Chem. Soc., 57 1935 , p. 1007. 4. Bigelow, WC., D.L. Pickett and WA. Zisman,J. Colloid Interface Sci., 1 1946 , p. 513. 5. Nuzzo, R.G. and D.L. Allara, J. Am. Chem. Soc., 105 1983 , p. 4481. 6. Ulaman, A., 1991 , An Introduction to Ultra-thin Organic Films from Langumir-Blodgtt to Self-Assembly, Academic Press, London. 7. Ulman, A., Chem....
Preparation
SAMs are prepared by dipping substrates such as evaporated gold films into a millimolar solution of the surfactant. The gold films of 500 2000 A thickness are made on substrates. The solution is normally made in hexane for long-chain surfactants and in ethanol for short chain surfactants. The process of assembly of monolayers on the surface involves two stages. During the first stage, the surfactants are rapidly pinned on the surface, followed by a slow reorganization step, during the second...
Info Kjb
Protease inhibitors for patients suffering from HIV Although technologies have come and gone, it is important to assess what they have given us. The industrial age of the 1900s gave us advanced agricultural practices like the use of chemical fertilizers, radio, TV, air conditioning, car, jet planes, modern medicines, fabrics, etc. which can help the rich live like the kings of the past, and also enable paupers to become kings if they have an appropriate understanding of the markets. The...