Whiskers defined

DEFINE GRAPHICS OPTIONS SET DEVICE DESTINATION TO MS OFFICE CGM FILE, REPLACE ANY EXISTING CGM FILE, RESET ANY SYMBOL DEFINITIONS, AND DEFINE DEFAULT FONT TYPE. filename fileref C whisker.cgm goptions... 

Figure 4.13 Variability in enantiomer fractions (EFs) of cis-chlordane and trans-chlordane at plots In grassland (G) and woodlands (W1 and W2) In Scotland. Box plot defined as follows top and bottom of whiskers are maximum and minimum EFs, respectively top and bottom of box are 25 and 75% percentiles, respectively line in box is median EF. (Reproduced with permission from Environmental Science and Technology, Enantioselective Degradation of Organochlorine Pesticides In Background Soils Variability In Field and Laboratory Studies, by Perihan Binnur Kurt-Karakus, Jacqueline L. Stroud et af, 41(14), 4965-4971. Copyright (2007) American Chemical Society)...

The concentration of dislocations is conventionally defined as the number of dislocation lines that intersects a unit area. Carefully prepared crystals may contain 10 dislocation lines per square centimeter, and some bulk crystals and crystal whiskers have been prepared free, or nearly free, of all dislocations after plastic deformation the concentration of dislocations increases tremendously, being as high as 10 to 10" dislocations per square centimeter for some heavily deformed metals. (We should not use cm" units so beware.)... 

In this chapter we have reviewed some of the most important characteristics of cellulose and cellulose based blends, composites and nanocomposites. The intrinsic properties of cellulose such as its remarkable mechanical properties have promoted its use as a reinforcement material for different composites. It has been showed that cellulose is a material with a defined hierarchy that tends to form fibrillar elements such as elementary fibrils, micro fibrils, and macro fibers. Physical and chemical processes allow us to obtain different scale cellulose reinforcements. Macro fibers, such as lignocellulosic fibers of sisal, jute, cabuya, etc. are used for the production of composites, whereas nano-sized fibers, such as whiskers or bacterial cellulose fibers are used to produce nanocomposites. Given that cellulose can be used to obtain macro- and nano-reinforcements, it can be used as raw material for the production of several composites and nanocomposites with many different applications. The understanding of the characteristics and properties of cellulose is important for the development of novel composites and nanocomposites with new applications. 

SiC whiskers were initially developed in the early 1960s. However, their use was originally to be applied to the reinforcement of metal matrices, such as aluminum. These metal matrix composites were only a small commercial success, mainly because of the high cost of the whiskers. The first application of whisker reinforcement to ceramics, and in particular alumina, did not occur until the 1980 s. For the purposes of this article, SiC whiskers will be defined to be acicular or needle-like shaped, discontinuous, nearly single crystals. 

VLS siiicon carbide whiskers with diameters ranging from <3 to 11 jm, and lengths ranging from 5 jm to <10 cm are readily obtained by metal catalyzed chemical vapor deposition. This process facilitates an exacting control over whisker shape and dimension in a batch or a continuous process. The diameter of the catalyst determines that of the whisker. Less well-defined whiskers have been obtained by vapor deposition, chemical mixing and carbothermal processes with diameters ranging from <3 pim to >30 nm. 

Some computer programs enhance the data presentation by identifying possible outliers separately. In such cases outliers are often defined as data points which are lower than the lower quartile, or higher than the upper quartile, by more than 1.5 times the interquartile range. The whiskers then only extend to these upper and lower limits or fences and outlying data are shown as separate points. (These refinements are not shown in Figure 6.2.)... 

The National Electronics Manufacturing Initiative (NEMI) has addressed the problem of tin whiskers in lead-free assemblies. A tin whisker is defined by them as... 

Another phenomenon in electronics degradation is whisker growth, defined as fifimentary growth on metallic materials [22-29]. Whiskers can be metallic or inorganic compounds. Although this behavior is still under investigation, it is reported to be a form of induced recrystaUization... 

Various techniques are used for the fabrication of semiconductor sensors. Conductance sensors from structurized sintered polycrystalline ceramics can be produced by thick- or thin-film technology. Chemically sensitive materials in the form of single crystals or whiskers can be attached to electrodes by thin- or thick-film techniques as well. Mass production of sensors requires that the resulting devices be characterized by a defined level of conductance. For example, the conductance of polycrystalline Sn02 can be adjusted by subsequent thermal treatment >800°C under a controlled partial pressure of oxygen. Another approach to defined conductance involves doping the semiconductor with antimony or fluorine. The reproducibility and stability of a sensor signal... 

Simms and Little" have examined the early stages of scale growth on 2.25%Cr-l%Mo steel at 600°C in dry flowing oxygen. Between 1 and 22 h they found that a thick oxide layer spreads laterally over a thin oxide layer. After 50 h, no thin areas of oxide layer were left. Whiskers gradually developed on the outer surface and these were well defined after 100 h. Fracture sections of the oxide revealed that the thin scales were duplex whereas the thicker scale was triplex, with a middle layer of Fej04 which spread laterally with time. The authors concluded that the first phases to develop were fine equiaxed a-FejOj overlying a doped spinel. Later, nucleation and... 

A box-and-whisker plot, or more simply a boxplot, is a complex graph that is based on quartiles to conveniently display multiple different properties of the data set. It can conveniently be used to compare different data sets. A box-and-whisker plot consists of two parts the box and the whiskers. The box is formed by the 25th (Ql) and 75th (Q3) percentile boundaries with the middle line invariably being the median (Q2). The whisker limits are defined using any of the following rules ... 

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