Unique properties and perfect structures of fullerenes and carbon nanotubes (CNTs) predetermine their great influence on nanotechnologies. These nanoclusters demonstrate outstanding mechanical, physical, chemical, electronic and optical properties and have attracted enormous attention of researchers worldwide [1-7].
Graphene, planar sheet of sp2-bonded carbon atoms, is the fundamental component of graphite and carbon nanotubes. The discovery of Geim and Novoselov in 2004 [8] has generated intense activity on graphene research. Sophisticated low-dimensional features and exceptional mechanical properties have given rise to many technological applications of pristine graphene in various fields. Its usage in electronic and optical devices, energy storage systems and composite materials, chemical sensors and drug delivery was suggested [9-16]. Soon after, the chemical functionalization of graphene became a center of interest in modern physics and chemistry [11]. The main motivations of these experimental and theoretical studies were modification of electronic properties via changing the band gap, potential use of functionalized graphene for hydrogen storage, search for techniques to massively produce ‘cheap’ graphene by chemical reduction of graphene oxide, oxidation and subsequent unzipping of graphene as a method to create graphene nanostructures of a given size [17-20] . However, the reactivity of graphene as a planar sheet is much worse than those of CNTs and fullerenes. Therefore, only a few functionalization techniques have been transferred from fullerene to graphene chemistry, such as azo, aryne and nitrene additions [21-23], Claisen rearrangement [24], 1,3-dipolar and Diels–Alder cycloadditions [25, 26].
Carbenes (CR2, R = H, ...
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...rest to consider the structural changes in graphene affected by dichlorocarbene. The influence of position of attached carbene species on graphene framework is also an important issue. Besides, to the best of our knowledge, no attempts have been made by researchers to ascertain what influence solvents offer on the binding energy of carbenes as well as on the band gap of functionalized graphene.
As described in the previous paragraphs, the functionalization of nanotubes and fullerenes with carbenes has been of importance. Taking into consideration the significance that graphene reveals nowadays, herein, we report comprehensive density functional theory study on the CCl2 functionalization of finite-size graphene sheets, focusing on equilibrium structures of the CCl2-attached graphene and the effects of attached dichlorocarbene on the electronic properties of graphene.
Rasmussen, T.; Jensen, J. F.; Ostergaard, N.; Tanner, D.; Ziegler, T.; Norrby, P. Chem. Eur. J., 2002, 8, 177.
Ultraviolet-B (UVB) radiation is a type of ultraviolet (means ‘beyond violet’) radiation that forms a part of the electromagnetic spectrum. Its primary natural source is the sun, but could also be emitted by artificial sources such as UVB lights, excimer lasers and fluorescents. Most UVB produced by sunlight is absorbed by oxygen in Earth’s atmosphere and forms the ozone layer of lower stratosphere. When the amount of ozone in the ozone layer is reduced, more UVB radiation reaches the surface of earth and can cause damaging effects to human health such as skin and eye, nevertheless UVB could also beneficial in some ways when it comes to produce vitamin D and used in medical devices.
Greta Christina eloquently puts into words something I know in theory, but can be hard to understand in practice in heterosexual relationships. In Are we having sex now or what? Christina details her record keeping of how many people she had sex with, and what she counted as sex. She talks about the limiting misconception of sex only being coitus, and other acts not “counting.” Christina writes of how when she started having sex with women her outdated system of what was sex and what was not sex was completely destroyed. By limiting sex to “penis in vagina,” Christina was discounting some of her favorite sexual experiances, and including ones she did not particularly enjoy.
The Scarlet Letter is a classic novel written by Nathaniel Hawthorne which entangles the lives of two characters Hester Prynne and Arthur Dimmesdale together through an unpardonable sin-adultery. With two different lifestyles, this act of adultery affects each of them differently. Hester is an average female citizen who is married to a Roger Chillingworth from Europe while Dimmesdale is a Puritan minister from England (61). Along the course of time after the act of adultery had happened, Hester could not hide the fact that she was bearing a child that was not of her husband, but from another man. She never reveals that this man is in fact Arthur Dimmesdale, and so only she receives the punishment of prison. Although it is Hester who receives the condemnation and punishment from the townspeople and officials, Dimmesdale is also punished by his conscience as he lives his life with the secret burden hanging between him and Hester.
Carbon is essential to many basic biological functions. Carbon’s unique properties are what make this element the basis of all living matter. Carbon is also responsible for the creation of monomers, polymers, and macromolecules. Monomers are small, simple units of carbon that have been strung together to form larger polymers. Polymers are more complex molecules made from individual carbon monomers. Macromolecules are very large molecules made from carbon based chains, such as polymers. The four classes of macromolecules include carbohydrates, proteins, lipids, and nucleic acids. The creation of these very important macromolecules is caused by the properties of carbon. These properties include carbon’s ability to form four covalent bonds, carbon’s
In summary, a new impedimetric biosensor for hCG determination in urine has been developed. A simple approach for generating a graphene-aminated surface to which an antibody binding with a suitable orientation for antigen binding is presented. The observed resistance to electron transfer increased linearly with increasing of log(hCG) concentration. The sensor response was not affected by chemical components present in synthetic urine indicating non-specific binding.
early 1990’s, no such material was known. In 1991, carbon nanotubes were discovered. Although not
24. Ujjal Kumar Sur, “Graphene: A Rising Star on the Horizon of Materials Science,” International Journal of Electrochemistry, vol. 2012, Article ID 237689, 12 pages, 2012. doi:10.1155/2012/237689
Www2.estrellamountain.edu, (2014). CHEMISTRY I: ATOMS AND MOLECULES. [online] Available at: http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookchem1.html [Accessed 20 May. 2014].
American Chemical Society. "Carbon nanotubes twice as strong as once thought." ScienceDaily, 16 Sep. 2010. Web. 5 Dec. 2013.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
V. Amarnath, D. C. Anthony, K. Amarnath, W. M. Valentine, L. A. Wetterau, D. G. J. Org. Chem. 1991, 56, p. 6924-6931.
Ionic compounds, when in the solid state, can be described as ionic lattices whose shapes are dictated by the need to place oppositely charged ions close to each other and similarly charged ions as far apart as possible. Though there is some structural diversity in ionic compounds, covalent compounds present us with a world of structural possibilities. From simple linear molecules like H2 to complex chains of atoms like butane (CH3CH2CH2CH3), covalent molecules can take on many shapes. To help decide which shape a polyatomic molecule might prefer we will use Valence Shell Electron Pair Repulsion theory (VSEPR). VSEPR states that electrons like to stay as far away from one another as possible to provide the lowest energy (i.e. most stable) structure for any bonding arrangement. In this way, VSEPR is a powerful tool for predicting the geometries of covalent molecules.
The formalistic approach allows the reader to look at a literary piece, and critique it according to its form, point of view, style, imagery, atmosphere, theme, and word choice. The formalistic views on form, allow us to look at the essential structure of the story. Stories such as Corona by Samuel Ray Delany show the aspects of a formalistic literary piece.
Graphite is another form of carbon. It occurs as a mineral in nature, but it can be made artificially from amorphous carbon. One of the main uses for graphite is for its lubricating qualities. Another is for the "lead" in pencils. Graphite is used as a heat resistant material and an electricity conductor. It is also used in nuclear reactors as a lubricator (Kinoshita 119-127).