Phonon-assisted electroluminescence from metallic carbon nanotubes and graphene.

We report on light emission from biased metallic single-wall carbon nanotube (SWNT), multiwall carbon nanotube (MWNT) and few-layer graphene (FLG) devices. SWNT devices were assembled from tubes with different diameters in the range 0.7-1.5 nm. They emit light in the visible spectrum with peaks at 1.4 and 1.8 eV. Similar peaks are observed for MWNT and FLG devices. We propose that this light emission is due to phonon-assisted radiative decay from populated pi* band states at the M point to the Fermi level at the K point. Since for most carbon nanotubes as well as for graphene the energy of unoccupied states at the M point is close to 1.6 eV, the observation of two emission peaks at approximately 1.6 +/- approximately 0.2 eV could indicate radiative decay under emission or absorption of optical phonons, respectively.

Influence of endohedral water on diameter sorting of single-walled carbon nanotubes by density gradient centrifugation.

Separation of single-walled carbon nanotubes (SWNT) by diameter is an important prerequisite for controlled experimental studies and efficient application of these systems. By comparing experimental data with molecular dynamics (MD) simulations, we demonstrate that water filling has a significant, tube-diameter dependent effect on the effective mass density of individual single-walled carbon nanotubes suspended in aqueous surfactant suspensions. We present a model for the effective density of the nanotube-surfactant complex in aqueous solution that permits a comprehensive description of its density across the entire, experimentally relevant range of SWNT diameters. Parameters for this model can be obtained from molecular dynamics simulations and/or experiment and help explain the subtle interplay of surfactant coverage and endohedral water in the separation of a particular diameter species of SWNT by gradient centrifugation.

Wideband-tuneable, nanotube mode-locked, fibre laser.

Ultrashort-pulse lasers with spectral tuning capability have widespread applications in fields such as spectroscopy, biomedical research and telecommunications. Mode-locked fibre lasers are convenient and powerful sources of ultrashort pulses, and the inclusion of a broadband saturable absorber as a passive optical switch inside the laser cavity may offer tuneability over a range of wavelengths. Semiconductor saturable absorber mirrors are widely used in fibre lasers, but their operating range is typically limited to a few tens of nanometres, and their fabrication can be challenging in the 1.3-1.5 microm wavelength region used for optical communications. Single-walled carbon nanotubes are excellent saturable absorbers because of their subpicosecond recovery time, low saturation intensity, polarization insensitivity, and mechanical and environmental robustness. Here, we engineer a nanotube-polycarbonate film with a wide bandwidth (>300 nm) around 1.55 microm, and then use it to demonstrate a 2.4 ps Er(3+)-doped fibre laser that is tuneable from 1,518 to 1,558 nm. In principle, different diameters and chiralities of nanotubes could be combined to enable compact, mode-locked fibre lasers that are tuneable over a much broader range of wavelengths than other systems.

Chirality distribution and transition energies of carbon nanotubes.

From resonant Raman scattering on isolated nanotubes we obtained the optical transition energies, the radial breathing mode frequency, and the Raman intensity of both metallic and semiconducting tubes. We unambiguously assigned the chiral index (n(1),n(2)) of approximately 50 nanotubes based solely on a third-neighbor tight-binding Kataura plot and find omega(RBM)=(214.4+/-2) cm(-1) nm/d+(18.7+/-2) cm(-1). In contrast to luminescence experiments we observe all chiralities including zigzag tubes. The Raman intensities have a systematic chiral-angle dependence confirming recent ab initio calculations.

Functional cooperation of Epstein-Barr virus nuclear antigen 2 and the survival motor neuron protein in transactivation of the viral LMP1 promoter.

Epstein-Barr virus nuclear antigen 2 (EBNA2) is essential for viral transformation of B cells and transactivates cellular and viral target genes by binding RBPJkappa tethered to cognate promoter elements. EBNA2 interacts with the DEAD-box protein DP103 (DDX20/Gemin3), which in turn is complexed to the survival motor neuron (SMN) protein. SMN is implicated in RNA processing, but a role in transcriptional regulation has also been suggested. Here, we show that DP103 and SMN are complexed in B cells and that SMN coactivates the viral LMP promoter in the presence of EBNA2 in reporter gene assays and in vivo. Subcellular localization studies revealed that nuclear gems and/or coiled bodies containing DP103 and SMN are targeted by EBNA2. Protein-protein interaction experiments demonstrated that DP103 binds to SMN exon 6 and that both EBNA2 and SMN interact with the C terminus of DP103. Furthermore, a DP103 binding-deficient SMN mutant was released from nuclear gems and/or coiled bodies and further enhanced coactivation. In addition, impaired transactivation of a DP103 binding-deficient EBNA2 mutant was rescued by overexpression of SMN. Testing different promoter constructs in luciferase assays showed that RBPJkappa is required but not sufficient for coactivation by EBNA2 and SMN. Overall, our data suggest that EBNA2 might target spliceosomal complexes by binding to DP103, thereby releasing SMN which subsequently exerts a coactivational function within the RNA-polymerase II transcription complex on the LMP1 promoter.

[Ureteric reimplantation in passage disturbances of the pelvic ureter (author's transl)]. / Die Ureterreimplantation bei Passagestörungen des pelvinen Harnleiters. Ein Erfahrungsbericht (1966 bis 1976).

Between 1966 and 1976 106 ureter reimplantations were performed in 94 patients. Subsequent checks in 48 patients with 53 reimplants showed good results in 39 cases (73.5%). In 5 cases the results were moderately good (9.4%) and in 9 cases (16.9%) poor. Since there was found insufficient correlation between infection and reflux direct reimplantation and/or plastic surgery of the flaps is recommended for the reconstruction operation.

[Urological complications in patients with multiple sclerosis (author's transl)]. / Urologische Komplikationen bei neurologischen Erlankungen.

63 patients with multiple sclerosis underwent urodynamic evaluation. Hyperreflexia of the bladder was found in 64% and areflexia in 8%. Hypertrophy or sclerosis of the bladder neck (internal sphincter) was detected in 27% of the patients and a spastic external sphincter (dyssynergia) was encountered in 57%. 16 patients were admitted for surgery: 9 for TUR of the bladder neck, 5 for percutaneous selective sacral nerve block, 2 for ileal diversion, 2 for prolonged bladder distension and 1 for nephrectomy for staghorn calculi of the renal pelvis. Highly effective conservative therapy is available in the form of Lioresal for treatment of the hyperactive detrusor muscle and Dibenzyran - an alpha-adrenergic blocking agent - to relieve bladder neck spasticity.

[Clinical picture of urogenital tuberculosis]. / Das klinische Bild der Urogenitaltuberkulose.

On the basis of a survey on 28 cases with ascertained urogenital tuberculosis from 1971 to 1975 clinical picture and findings of the examinations are discussed. The cases in question are not a representative cross-section, since primarily ascertained cases of urogenital tuberculosis are treated in special departments. On account of the participation of the bladder which - compared with former cases - seems to be less frequent in interest of the early diagnosis is referred to the importance of the urinary findings and the excretion urography.