We present a theoretical study of the structure, local curvature angles, and reactivity of cap-ended (7,0), defective and nondefective carbon nanotubes. We find that the most reactive sites are the atoms that form part of the caps even when the Stone-Wales defect is present. Each carbon in the carbon nanotube is located at the top of a pyramidal structure with three walls of 5-, 6-, or 7-carbon...

Data are presented from the South Wales Congenital Malformation Survey (92,982 births 1964-6 inclusive) showing that within areas in South Wales there exists an inverse relation between previous spontaneous abortion rate and the prevalence at birth of neural tube defect (anencephaly or spina bifida cystica or both). This relation is independent of social class, parity, and maternal age, and is ...

Introduction An 80-year-old man with a previous history of recurrent urinary tract infections presented with intermittent, painful and whole stream gross haematuria for 2 months. Physical examination was unrevealing. The result of urine cytology was negative for malignancy. Intravenous pyelography (IVP) revealed left hydronephrosis with obstruction at left ureterovesical junction, radiolucent f...

Fullerene-Like (FL) sulpho-carbide (CSx) compounds have been addressed by first principles calculations. Geometry optimization and cohesive energy results are presented for the relative stability of precursor species such as C2S, CS2, and C2S2 in isolated form. The energy cost for structural defects, arising from the substitution of C by S is also reported. Similar to previously synthesized FL-...

We have performed first-principles calculations of graphene edge stresses, which display two interesting quantum manifestations absent from the classical interpretation: the armchair edge stress oscillates with a nanoribbon width, and the zigzag edge stress is noticeably reduced by spin polarization. Such quantum stress effects in turn manifest in mechanical edge twisting and warping instabilit...

We investigate Raman spectra of graphite oxide and functionalized graphene sheets with epoxy and hydroxyl groups and Stone-Wales and 5-8-5 defects by first-principles calculations to interpret our experimental results. Only the alternating pattern of single-double carbon bonds within the sp2 carbon ribbons provides a satisfactory explanation for the experimentally observed blue shift of the G b...

Sequential atomic rearrangements leading to the coalescence of fullerene cages or tubes are derived by topological analysis. Qualitative reasoning assists the search for the minimum-energy path, which consists of a jump-to-contact formation of covalent bonds between the separate cages and the following ‘‘plastic flow’’ by exclusively Stone-Wales bond rotations. A connecting neck forms and grows...