Tubularized incised plate urethroplasty repair in adult hypospadias patients. Are results similar to those reported in the pediatric age group? A prospective study

AbstractObjectiveMost studies published in the literature report on the results of tubularized incised plate urethroplasty (TIPU) for hypospadias repair in children. Hence, the objective of this study was to evaluate the results of TIPU repair in adults.Patients and methodsThe records of 60 adult patients with primary hypospadias treated with TIPU between April 2009 and May 2012 were reviewed. All the procedures were done by the same surgeon under similar conditions and using the same kind of instruments and suture material. On clinical examination, the meatal location, as well as the presence/absence of chordee and penile torsion was assessed. The quality of the spongiosum and the width of the urethral plate were evaluated intraoperatively. The postoperative complications and results were recorded and the data were analyzed.ResultsThe patients’ age ranged from 16 to 27 years with a mean of 21 years. Out of the 60 cases, 43 (72%) had distal penile, 7 (11%) mid-penile and 10 (17%) proximal hypospadias. Penile torsion was present in 10 (17%) cases with 80% having a torsion ≤45° and 20% having a torsion of 45–90°. Ventral chordee ranging from 30° to 90° was present in 14 (23%) cases. Chordee correction was possible by penile de-gloving in 4 (29%) patients (2 with distal and 2 with mid-penile hypospadias), by further mobilization of the urethral plate with the corpus spongiosum in 3 (21%) and by proximal urethral mobilization in another 6 (42%) patients with proximal hypospadias. One (7%) patient also required tunica albuginea plication. The urethral plate was wide in 22 (37%), average in 26 (43%) and narrow in 12 (20%) patients. Fifty percent of the patients with a narrow urethral plate developed complications, compared to 15% of the patients whose urethral plate had an average width and none of the patients with a wide urethral plate. The spongiosum was well developed in 38 (63%) patients, while in 11 (18%) patients each the spongiosum was moderately and poorly developed. The complication rates were significantly higher (55%) in patients with a poorly developed spongiosum as compared to those with a well-developed spongiosum. The overall complication rate was 17% including fistula in 10% of the patients (2 patients with mid-penile and 4 patients with proximal hypospadias). Meatal stenosis was found in 4 patients with distal hypospadias (7%) who responded well to meatal dilatation. The fistula cases required surgical repair with a success rate of 100%. Mean hospitalization and follow-up were 9 days and 6–24 (median 37) months, respectively.ConclusionsComplications encountered in the present study were urethral fistula and meatal stenosis with a higher incidence in patients with proximal hypospadias than reported in the literature. The important factors for the outcome of TIPU were the severity of hypospadias, the degree of curvature and the development of the spongiosum and urethral plate. Proximal hypospadias with a poor urethral plate and severe curvature in adults is not suitable for TIPU. In such cases, single-stage flap urethroplasty or two-stage buccal mucosal urethroplasty should be considered instead

External Bias Dependent Direct To Indirect Bandgap Transition in Graphene Nanoribbon

In this work, using self-consistent tight-binding calculations, for the first time, we show that a direct to indirect bandgap transition is possible in an armchair graphene nanoribbon by the application of an external bias along the width of the ribbon, opening up the possibility of new device applications. With the help of Dirac equation, we qualitatively explain this bandgap transition using the asymmetry in the spatial distribution of the perturbation potential produced inside the nanoribbon by the external bias. This is followed by the verification of the bandgap trends with a numerical technique using Magnus expansion of matrix exponentials. Finally, we show that the carrier effective masses possess tunable sharp characters in the vicinity of the bandgap transition points.Comment: Accepted for publication in Nano Letter

Intrinsic Limits of Subthreshold Slope in Biased Bilayer Graphene Transistor

In this work, we investigate the intrinsic limits of subthreshold slope in a dual gated bilayer graphene transistor using a coupled self-consistent Poisson-bandstructure solver. We benchmark the solver by matching the bias dependent bandgap results obtained from the solver against published experimental data. We show that the intrinsic bias dependence of the electronic structure and the self-consistent electrostatics limit the subthreshold slope obtained in such a transistor well above the Boltzmann limit of 60mV/decade at room temperature, but much below the results experimentally shown till date, indicating room for technological improvement of bilayer graphene.Comment: 10 pages, 2 figure

Structural stability studies of graphene in sintered ceramic nanocomposites

The post-sintering structural stability of graphene in alumina nanocomposites synthesised by Spark Plasma Sintering (SPS) and Hot Pressing (HP) was compared. Raman spectroscopy, thermogravimetric analyses and electrical conductivity analyses were conducted to characterise degradation of graphene due to the utilisation of different sintering techniques and conditions. Scanning Electron Microscopy confirmed good dispersion of graphene in SPSed and HPed sample. Graphene in SPSed and HPed nanocomposite samples sintered using longer durations (60 min) were found to possess higher crystallinity, thermal stability and electrical conductivity as compared to SPSed samples sintered using shorter sintering durations (10–20 min). This was attributed to the thermally induced graphitisation caused by longer sintering durations, which was lacking in SPSed samples processed using shorter sintering durations and lower temperature. No additional effect of DC pulsed current on the structural stability of graphene for nanocomposites were observed for samples prepared by SPS

Pulsed emission of TeV gamma rays from Vela pulsar

The Ooty atmospheric Cerenkov array, consisting of 10 parabolic mirrors of 0.9 m diameter and 8 of 1.5 m diameter, was used for observations on the Vela pulsar to see if it emits gamma rays in the TeV energy range. During the winter of 1984-85, the array was split into two parts: (1) consisting wholly of the smaller mirrors, and (2) wholly of the bigger mirrors. The two arrays were operated at two different sites to distinguish a marginally significant genuine pulsar signal from spurious signals produced trivially by chance fluctuations in the background rates. All the mirrors were pointed at the celestial object to track it for durations of the order of 1 to 6 hours during clear moonless nights. The event time data is analyzed to detect a possible pulsed emission of TeV gamma rays using the contemporaneous pulsar elements on the basis of their radio observations on the Vela pulsar. Results from the analyses of observations made during the winters of 1982-83 and 1984-85 on steady pulsed emission and on possible transient emission is presented

Secondary periodicities of microbursts of TeV gamma rays from the Crab pulsar

Observations were made during the past several years on the Crab pulsar using the Ooty atmospheric Cerenkov array with the aim of detecting possible emission of ultra high energy gamma rays by the pulsar. During the course of these observations, it was found that the Crab pulsar emits TeV gamma rays in bursts of short duration. The microbursts of TeV gamma rays from the Crab pulsar, which were seen in the data of at least three years, also reveal interesting secondary periodicities. It was noticed at first that some bursts could be connected with the others that occurred during the same night or during the next two nights with integral number of cycles of periods 43 + or - 1 minute. Ten possible periods in the vicinity of 43 minutes were determined for all the combinations of bursts for each year. The best values of periods thus obtained were different from year to year. But when, instead of the real time, the number of Crab cycles elapsed between the bursts was used as the unit of time, two values of burst periods - 77460 and 77770 Crab cycles - were found to be significant in the data of at least two years. A Monte Carlo simulation using 1500 trial periods chosen randomly within + or - 5 minutes of the original burst period did not reveal any value of the period as significant