Whisker Isolation

A new series of biomimetic, stimuli-responsive nanocomposites, which change their mechanical properties upon exposure to physiological conditions, was reported by Shanmuganathan et al. (2010). The materials were produced by introducing percolating networks of cellulose whiskers isolated from cotton into... 

Rosa, S. M. L., Rehman, N., de Miranda, M. I. G., Nachtigall, S. M. B., Bica, C. I. D. Chlorine-free extraction of cellulose from rice husk and whisker isolation. Carbohydrate Polymers 2012, 87,1131-1138. 

A composite material (1) is a material consisting of two or more physically and/or chemically distinct, suitably arranged or distributed phases, generally having characteristics different from those of any components in isolation. Usually one component acts as a matrix in which the reinforcing phase is distributed. When the continuous phase or matrix is a metal, the composite is a metal-matrix composite (MMC). The reinforcement can be in the form of particles, whiskers, short fibers, or continuous fibers (see Composite materials). 

The similar term nanosized cellulose is used in case of isolated crystallites and whiskers formed by acid-catalyzed degradation of cellulosics. This field and the application of that nanosized cellulose, e.g. in composites, have been intensively investigated. Typical examples have been presented in current papers [3,4] and at the 231st American Chemical Society (ACS) national meeting in Atlanta. 

A new receptor protein has been isolated from the sensory tissue found on the barbels (whiskers) of the Louisiana blue catfish. Studies have shown that this protein interacts strongly with glutamate. An affinity column was prepared by... 

Many significant scientific and technological advances have recently been made in the area of the isolation of nanofibrils (otherwise called chitin nanocrystals, or whiskers). In particular, articles have been pubhshed dealing with the following advances (1) nanochitin isolated after hydrolysis with HCl (2) nanochitin isolated mechanically in the presence of minor amounts of acetic acid (3) nanochitosan obtained from partially deacetylated chitin and (4) defibrillation of chitosan. These advances are of such importance that they overshadow the technology developed during the previous years, for reasons that will be apparent below [33]. 

Lu, Y.S., Weng, L.H., Zhang, L.N. Morphology and properties of soy protein isolate thermoplastics reinforced with chitin whiskers. Biomacromolecules. 5, 1046-1051 (2004)... 

There are basically two families of nanosized cellulosic particles (1) Nanofibrillar cellulose, which includes mechanically isolated microfibrils, chemically isolated microfibrils (TEMPO-oxidation), bacterial cellulose and can be considered spaghetti-like, and (2) Cellulose nanocrystals - rods of highly crystalline cellulose which are isolated by acid hydrolysis. Cellulose nanocrystals are represented in literature by synonyms like cellulose whiskers, cellulose nanowhiskers, cellulose microfibrils, micro-crystalline cellulose and nanocrystalline cellulose because they are not yet commercially available. These are needle-shaped (100 run to 200 run X 10 nm), highly crystalline, strong (E - 150 GPa) and form liquid crystal suspensions. 

Cellulose nanocrystals are rods of highly crystalline cellulose which are usually isolated by acid hydrolysis Cellulose nanocrystals are represented in literature by synonyms like cellulose whiskers, cellulose nanowhiskers, cellulose microfibrils. 

What if any is the effect of connectivity on the behavior of the photochromic composite described in Section 9.4 in the following cases (a) a 0-3 composite isolated sensor particles in a three-dimensional actuator matrix (b) a 1-3 composite sensor fibers or whiskers in an actuator matrix and (c) a 2-2 composite sensor layers alternated with actuator layers. 

The recent interest in using stiff nanometric particles as reinforcement materials in polymeric matrixes, composites, or nanocomposites has been increasing. Two good examples of these types of particles are carbon nanotubes and cellulose nanofibers. Cellulose nanofibers, also reported in the literature as whiskers, nanocrystals, cellulose crystallites, or crystals, are the crystalline domains of ceUulosic fibers, isolated by means of acid hydrolysis, and are called in this way due to theb physical characteristics of stiffness, thickness, and length (Souza and Borsali 2004). 

Bondeson D, Oksman K (2007a) Dispersion and characteristics of surfactant modifled cellulose whiskers nanocomposites. Compos Interface 14 617-630 Bondeson D, Oksman K (2007b) Polylactic acid/cellulose whisker nanocomposites modifled by polyvinyl alcohol. Compos Part A 38 2486-2492 Bondeson D, Mathew A, Oksman K (2006a) Optimization of the isolation of nanocrystals from microcrystalline cellulose by acid hydrolysis. Cellulose 13 171-180 Bondeson D, Kvien 1, Oksman K (2006b) ACS symposium series, vol 938. American Chemical Society, Washington, DC... 

Fig. 5A-D. High magnification of DNA-bound poly(ADP-ribose) polymerase digested with micrococcal nuclease for 30 min. A shows an isolated complex with the same size and density as in undigested sample. No free DNA whiskers are detectable. B and C show some larger structures made of short bent DNA fragments with possible remnants of enzyme. In D the DNA is more extended and probably devoid of protein. The bar indicates 100 nm for all pictures...

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