Nanoparticles impact

In this chapter, an introduction of experimental and theoretical studies on nanoparticles collision has been made, as nanoparticles impact on an ultra-smooth surface always occur in the ultra-smooth surface manufacturing. Then the development of CMP technology is introduced. And at last, the polishing of magnetic head surface is discussed. 

Polished surface is usually observed by optical interference techniques, e.g.. Chapman MP2000+, WYKO, and Zygo. As shown in Table 1, different parameters of a polished surface, e.g., the surface waviness, roughness, flatness, dub-off, roll- 

Global planeness and large scale scratches are usually evaluated by HDI instruments as shown in Fig. 3(a) [8], which is a surface reflectance analyzer to measure flatness, waviness, roughness of a surface, and observe scratches (Fig. 3(h)), pits (Fig. 3(c)), particles (Fig. 3(d)) on a global surface. These surface defects can also be observed by SEM, TEM, and AFM. Shapes of slurry particles can be observed by SEM and TEM, and their movement in liquid by the fluorometry technique as shown in Chapter2. 

2 Experimental Observation of Nanoparticles Collision with Solid Surface 

State Key Laboratory of Tribology, Tsinghua University, Beijing, China. 

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In vitro evaluation of SiC nanoparticles impact on A549 pulmonary cells cyto-, geno-toxicity and oxidative stress. Toxicol Lett 198(3) 324-330... 

StuarL E. J. E. Rees, N. V. Compton, R. G. 2012. Particle-impact voltammetry The reduction of hydrogen peroxide at silver nanoparticles impacting a carbon electrode. Chem. Phys. Lett. 531 94-97. 

Ellison, J. Tschufik, K. StuarL E. J. E. et al. 2013. Get more out of your data A new approach to agglomeration and aggregation studies using nanoparticle impact experiments. Chem. Open 2(2) 69-75. 

An alternative and at least in principle much simpler and easier electrochemical approach to that of the previous section, in which nanoparticles are sequentially isolated, immobilised on an electrode and then analysed via stripping voltammetry, is the direct study of the nanoparticles suspended in a solution phase into which an electrode under potentiostatic control is introduced. The movement of the nanoparticles in the solution is expected to approximate to Brownian which from time to time will bring the nanoparticles close to or in physical contact with the electrode to which they can either stick or rebound, unless the electrode is held at a potential corresponding to the oxidation or reduction of the nanoparticles or at least the surface of the nanoparticles. In the latter case, the nanoparticle impacts on the electrode are revealed by a pulse of current, as shown schematically in Fig. 8.4. These spikes can be used to identify ( fingerprint ) the nanoparticles (by virtue of their onset potentials ), measure their concentrations and to size them as discussed in more detail below. This type of measurement is currently subject to significant levels of interest (see reference (32) for an early review). 

Lees JC, Ellison J, Batchelor-McAuley C, Tschulik K, Damm C, Omanovic D, Compton RG (2013) Nanoparticle impacts show high-ionic-strength citrate avoids aggregation of silver nanoparticles. ChemPhysChem 14 3895-3897... 

The biological impact of starch capped copper nanoparticles on mouse embryonic fibroblast (3T3L1) cells in vitro) was also evaluated by various parameters. More than 85 % of the 3T3Llcells were found to be viable, even after 20 hours time exposure which implies minimum impact on cell viability and morphology. The study demonstrates dose dependent cytotoxic potential of SCuNPs, that is non cytotoxic in the nanogram dose and moderately cytotoxic in the microgram doses (Fig. 10). Comparison of SCuNPs with Cu ions and uncapped copper nanoparticles (UCuNPs) revealed that, ions are more cytotoxic than SCuNPs. This observation supports the theory of slow release of ions from starch coated nanoparticles. 

Due to particles extrusion, crystal lattice deformation expands to the adjacent area, though the deformation strength reduces gradually (Figs. 10(a)-10(other hand, after impacting, the particle may retain to plow the surface for a short distance to exhaust the kinetic energy of the particle. As a result, parts of the free atoms break apart from the substrate and pile up as atom clusters before the particle. The observation is consistent with results of molecular dynamics simulation of the nanometric cutting of silicon [15] and collision of the nanoparticle with the solid surface [16]. 

One of the few disadvantages associated with nanoparticle incorporation concerns the loss of some properties. Some of the data presented have suggested that nanoclay modification of polymers such as polyamide could reduce impact performance [28]. Nanofillers are sometimes very matrix-specific. High cost of nanofillers prohibits their use. 

The development of DNA sensors and high-density DNA arrays has been prompted by the tremendous demands for innovative analytical tools capable of delivering the genetic information in a faster, simpler, and cheaper manner at the sample source, compared to traditional nucleic acid assays. Nanoparticle-biopolymer conjugates offer great potential for DNA diagnostics and can have a profound impact upon bioanalytical chemistry. Nanoparticle/polynucleotide assemblies for advanced electrical detection of DNA sequences have been reviewed by Wang [145]. 

Bifunctional spacer molecules of different sizes have been used to construct nanoparticle networks formed via self-assembly of arrays of metal colloid particles prepared via reductive stabilization [88,309,310]. A combination of physical methods such as TEM, XAS, ASAXS, metastable impact electron spectroscopy (MIES), and ultraviolet photoelectron spectroscopy (UPS) has revealed that the particles are interlinked through rigid spacer molecules with proton-active functional groups to bind at the active aluminium-carbon sites in the metal-organic protecting shells [88]. 

Since 1976 until present time Toshima-t5q)e nanocolloids always had a major impact on catalysis and electrocatalysis at nanoparticle surfaces [47,210-213,398-407]. The main advantages of these products lie in the efficient control of the inner structure and morphology especially of bimetallic and even multimetallic catalyst systems. 

Some of the reports are as follows. Mizukoshi et al. [31] reported ultrasound assisted reduction processes of Pt(IV) ions in the presence of anionic, cationic and non-ionic surfactant. They found that radicals formed from the reaction of the surfactants with primary radicals sonolysis of water and direct thermal decomposition of surfactants during collapsing of cavities contribute to reduction of metal ions. Fujimoto et al. [32] reported metal and alloy nanoparticles of Au, Pd and ft, and Mn02 prepared by reduction method in presence of surfactant and sonication environment. They found that surfactant shows stabilization of metal particles and has impact on narrow particle size distribution during sonication process. Abbas et al. [33] carried out the effects of different operational parameters in sodium chloride sonocrystallisation, namely temperature, ultrasonic power and concentration sodium. They found that the sonocrystallization is effective method for preparation of small NaCl crystals for pharmaceutical aerosol preparation. The crystal growth then occurs in supersaturated solution. Mersmann et al. (2001) [21] and Guo et al. [34] reported that the relative supersaturation in reactive crystallization is decisive for the crystal size and depends on the following factors. 

It has been demonstrated that the length of the hydrocarbon solvent molecule can have a significant impact of the stability of sterically stabilized nanoparticles [24, 30]. The solvation of a sterically stabilized nanoparticle depends on the interaction parameter, %, between the solvent and the ligand [25, 30-33], such that... 

Bartlett DW, Davis ME (2008) Impact of tumor-specific targeting and dosing schedule on tumor growth inhibition after intravenous administration of siRNA-containing nanoparticles. Biotechnol Bioeng 99 975-985... 

Bartlett DW, Su H, Hildebrandt IJ, Weber WA, Davis ME (2007) Impact of tumor-specific targeting on the biodistribution and efficacy of siRNA nanoparticles measured by multimodality in vivo imaging. Proc Natl Acad Sci USA 104 15549-15554... 

Another advantage cited for organic electronics is their perceived low environmental impact and high expected consumer safety. This assumption is generally based on the notion that plastics are easily recycled and are considered safe to humans and animals. However, the materials used are often completely new compositions with poorly understood health and safety attributes. The assumption that all plastics are completely safe for humans is inaccurate, as is exemplified by recent concerns about the toxicity of polyvinyl chloride (PVC).39 In contrast, most inorganic nanoparticle materials are already on the consumer market and have extensive historical data on their safety in a variety of applications. Some materials, such as zinc oxide, are even considered reasonably safe for ingestion and therefore are commonly used in food and cosmetics. However, the health effects and interactions of nanoparticles on the human body are still a topic of debate.40... 

Warheit, D. 2004. Nanoparticles health impacts . Materials Today 7 32-35. 

More recently, Dupont and coworkers studied the impact of the steric effect in the hydrogenation of monoalkylbenzenes by zerovalent nanoparticles (Ir, Rh, Ru) in the ionic liquid BMI PF6. The results, when compared with those obtained with the classical supported heterogeneous catalysts, showed a relationship between the reaction constants and the steric factors [106]. 

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