Synthesis and characterization of polystyrene-blockpoly(vinylbenzoic acid): a promising compound for manipulating photoresponsive properties at the nanoscale

"Published online: 27 January 2015"Using reversible addition-fragmentation chain transfer (RAFT) polymerization, the effect of PSt macroRAFT and 4VBA ratio on the synthesis of a carboxylic acid functional block copolymer (PSt-b-P4VBA) was studied. PSt macroRAFT polymer was initially prepared followed by the insertion of 4-vinylbenzoic acid (4VBA) monomer. The chemical structure of the diblock copolymer was confirmed by NMR and FTIR. The effect of PSt macroRAFT and 4VBA ratio on copolymerization yield and on molecular weight distribution was assessed by gel permeation chromatography. The rate of polymerization did not change as the 4VBA/PSt macroRAFT ratio increased, indicating an ideal amount of 4VBA insertion. An optimal ratio of [PSt macroRAFT]:[AIBN]:[4VBA] was 1.2:1:180. DSC and XRD confirmed the amorphous structure of homo and copolymer. Thermal stability was higher for PSt-b-P4VBA forming activated porous carbon char by dehydration, carbonization and oxidation. SEM and STEM observations showed a morphological evolution between PSt macroRAFT and the correspondent copolymer.The authors acknowledge the n-STeP-Nanostructured systems for Tailored Performance, with reference NORTE-07-0124-FEDER-000039, supported by the Programa Operacional Regional do Norte (ON.2), PEst-C/CTM/LA0025/2013 (Strategic Project-LA 25-2013-2014)

Combined Non Transecting Anastomotic Urethroplasty with Buccal Mucosal Augmentation for the Management of Segmental Urethral Strictures – A Retrospective Study

Background: Urethral strictures are one of the common problems encountered by the urologist and affect one in 10,000 males. The aetiology can be secondary to inammation, trauma or can be idiopathic. The time honoured management of strictures by dilatation was associated with high recurrence rates. Currently various techniques of urethroplasty are used in the management of strictures. We herein describe our early experience with a combined technique of non transecting urethroplasty with buccal mucosal augmentation for the management of segmental urethral strictures. Objective: To report our early experience for the treatment of segmental urethral strictures with combined non transecting anastomotic urethroplasty and buccal mucosal augmentation. Material and Methods: A total of three patients underwent non transecting anastomotic urethroplasty with buccal mucosal augmentation between January 2010 and December 2013 with a minimum follow up of one year. Results: At one year follow up all patients were free of obstructive symptoms and, none of the patients developed recurrence. No patient developed erectile dysfunction during the course of follow up. Conc lusion: Non tr ans e c ting ana stomoti c urethroplasty with buccal mucosal augmentation is a viable option for long segment strictures with diverticulum and segmental urethral strictures. This method helps in reducing the length of buccal graft required. Due to the non-transecting nature of the surgery, blood supply to urethra is maintained, there is good graft uptake and the incidence of erectile dysfunction is reduce

Performance of the ocean state forecast system at Indian National Centre for Ocean Information Services

The reliability of the operational Ocean State Forecast system at the Indian National Centre for Ocean Information Services (INCOIS) during tropical cyclones that affect the coastline of India is described in this article. The performance of this system during cyclone Thane that severely affected the southeast coast of India during the last week of December 2011 is reported here. Spec-tral wave model is used for forecasting the wave fields generated by the tropical cyclone and vali-dation of the same is done using real-time automated observation systems. The validation results indicate that the forecasted wave parameters agree well with the measurements. The feedback from the user community indicates that the forecast was reliable and highly useful. Alerts based on this operational ocean state forecast system are thus useful for protecting the property and lives of the coastal communities along the coastline of India. INCOIS is extending this service for the benefit of the other countries along the Indian Ocean rim

Wave forecasting and monitoring during very severe cyclone Phailin in the Bay of Bengal

Wave fields, both measured and forecast during the very severe cyclone Phailin, are discussed in this communication. Waves having maximum height of 13.54 m were recorded at Gopalpur, the landfall point of the cyclone. The forecast and observed significant wave heights matched well at Gopalpur with correlation coefficient of 0.98, RMS error of 0.35 m and scatter index of 14%. Forecasts were also validated in the open ocean and found to be reliable (scatter index < 15%). The study also revealed the presence of Southern Ocean swells with a peak period of 20-22 sec hitting Gopalpur coast along with the cyclone-generated waves

Small-scale cosmic ray anisotropy observed by the GRAPES-3 experiment at TeV energies

GRAPES-3 is a mid-altitude (2200 m) and near equatorial ($11.4^{\circ}$ North) air shower array, overlapping in its field of view for cosmic ray observations with experiments that are located in Northern and Southern hemispheres. We analyze a sample of $3.7\times10^9$ cosmic ray events collected by the GRAPES-3 experiment between 1 January 2013 and 31 December 2016 with a median energy of $\sim16$ TeV for study of small-scale ($<60^{\circ}$) angular scale anisotropies. We observed two structures labeled as A and B, deviate from the expected isotropic distribution of cosmic rays in a statistically significant manner. Structure `A' spans $50^{\circ}$ to $80^{\circ}$ in the right ascension and $-15^{\circ}$ to $30^{\circ}$ in the declination coordinate. The relative excess observed in the structure A is at the level of $(6.5\pm1.3)\times10^{-4}$ with a statistical significance of 6.8 standard deviations. Structure `B' is observed in the right ascension range of $110^{\circ}$ to $140^{\circ}$. The relative excess observed in this region is at the level of $(4.9\pm1.4)\times10^{-4}$ with a statistical significance of 4.7 standard deviations. These structures are consistent with those reported by Milagro, ARGO-YBJ, and HAWC. These observations could provide a better understanding of the cosmic ray sources, propagation and the magnetic structures in our Galaxy