Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs in the synthesis of SWCNTs and highlight key ongoing research areas and challenges. A few key applications that capitalize on the properties of SWCNTs are also reviewed with respect to the recent synthesis breakthroughs and ways in which synthesis science can enable advances in these applications. While the primary focus of this review is on the science framework of SWCNT growth, we draw connections to mechanisms underlying the synthesis of other 1D and 2D materials such as boron nitride nanotubes and graphene.

We study the organization of topological defects in a system of nematogens confined to the two-dimensional sphere (S2). We first perform Monte Carlo simulations of a fluid system of hard rods (spherocylinders) living in the tangent plane of S2. The sphere is adiabatically compressed until we reach a jammed nematic state with maximum packing density. The nematic state exhibits four +1/2 disclinations arrayed on a great circle. This arises from the high elastic anisotropy of the system in which splay (K1) is far softer than bending (K3). We also introduce and study a lattice nematic model on S2 with tunable elastic constants and map out the preferred defect locations as a function of elastic anisotropy. We find a one-parameter family of degenerate ground states in the extreme splay-dominated limit K_{3}/K_{1}-->infinity. Thus the global defect geometry is controllable by tuning the relative splay to bend modulus.

An experiment was conducted to assess the physiological effects of a diet rich in foods cotaining phosphate additives. During a 4-week control period, eight adults were fed a balanced diet free of phosphate additives providing approximately 95 g protein 0.7 g Ca and 1.0 g P per day. During a subsequent 4-week period, food items containing phosphate additives were substituted for counterpart items devoid of added phosphates. This diet contained 0.7 g Ca and 2.1 g P per day. The introduction of foods containing phosphate additives was associated with intestinal distress, soft stools or mild diarrhea. These symptoms subsided in six subjects but occurred intermittently throughout the experimental period in the other two subjects. The high-phosphorus diet induced increases in serum phosphorus and urinary phosphorus and decreases in serum calcium and urinary calcium. Hydroxyproline excretion in the urine was increased and cyclic AMP excretion was elevated in six of the eight subjects. These changes are analogous to those seen in experimental animals fed high-phosphorus diets which were shown to be due to enhanced parathyroid activity (secondary hyperparathyroidism). The use of phosphate food additives is discussed with respect to their possible stimulating effect on adult bone resorption.

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Covalent functionalization of boron nitride nanotubes via reduction chemistry Shin, Homin; Guan, Jingwen; Zgierski, Marek Z.; Kim, Keun S.; Kingston, Christopher T.; Simard, Benoit http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=fr L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21277400&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=21277400&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions?Contact the NRC Publications Archive team at PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/acsnano.5b06523 ACS Nano, 9, 12, pp. 12573-12582, 2015-11-18 B oron nitride nanotubes (BNNTs) consist of seamless cylinders of alternating boron and nitrogen atoms in a hexagonal BN bonding network. 1,2 Since their first synthesis in 1995, 1 BNNTs have been considered as revolutionary materials due to their unique properties, which are as compelling as those of carbon nanotubes (CNTs). Despite their structural similarity to CNTs, BNNTs also exhibit a range of physical and chemical properties distinct from CNTs, which are mainly attributed to the partial ionic bonding character of BN. For example, the mixed ionic and covalent bonding nature of BNNTs results in their wide band gaps, around 6.0 eV independent of diameter and chirality. Figure 1 illustrates the calculated valence electron density distribution of a (6,6) CNT and BNNT. The valence charges of a CNT are equally distributed around C atoms, indicating a strong covalent CÀC bond network as well as the delocalized electrons, while the bonding electrons of BNNT are more concentrated around N atoms with an asymmetric charge distribu...

We study the rich crystalline phase behavior of amphiphilic spherical Janus colloids using a new formulation of self-consistent phonon theory that includes coupled translational and rotational entropic and enthalpic contributions to the free energy. In contrast to homogeneous spheres, broken rotational symmetry can result in more exotic crystals that possess distinct orientational patterns, and also plastic crystals. Ground states are identified based on the compatibility between the patch geometry of particles (e.g., patch coverage, number, shape) and lattice symmetry. We derive the explicit coupled self-consistent equations for translational and rotational localization parameters for effectively 2-dimensional dense monolayers of Janus crystals. The equations are numerically solved for a given crystal symmetry, thermodynamic state, and patch orientational order, and the thermodynamic stability of different phases is determined. For hexagonal packing, we predict with increasing temperature or decreasing attraction strength the possibility of a phase sequence of maximally bonded zigzag stripe, trimer, and rotationally disordered plastic crystal phases (or a phase sequence of trimer, dimer, and plastic crystal), which depends sensitively on particle chemical composition (Janus balance) and pressure. The role of rotational entropy in stabilizing the intermediate trimer (or dimer) phase at intermediate temperatures and high pressures is discussed in detail. Evolution of the center-of-mass vibrational and rotational amplitudes with thermodynamic state and Janus balance is also determined.