Plasticizer-Induced Enhancement of Mesoscale Dissymmetry in Thin Films of Chiral Polymers with Variable Chain Length.

Conjugated polymers with chiral side chains are of interest in areas including chiral photonics, optoelectronics, and chemical and biological sensing. However, the low dissymmetry factors of most neat polymer thin films have limited their practical application. Here, a robust method to increase the absorption dissymmetry factor in a poly-fluorene-thiophene (PF8TS series) system is demonstrated by varying molecular weight and introducing an achiral plasticizer, polyethylene mono alcohol (PEM-OH). Extending chain length within the optimal range and adding this long-chain alcohol significantly enhance the chiroptical properties of spin-coated and annealed thin films. Mueller matrix spectroscopic ellipsometry (MMSE) analysis shows good agreement with the steady-state transmission measurements confirming a strong chiral response (circular dichroism (CD) and circular birefringence (CB)), ruling out linear dichroism, birefringence, and specific reflection effects. Solid-state NMR studies of annealed hybrid chiral polymer systems show enhancement of signals associated with aromatic π-stacked backbone and the ordered side-chain conformations. Further studies using Raman spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and polarized optical microscopy (POM) indicate that PEM-OH facilitates mesoscopic crystal domain ordering upon annealing. This provides new insights into routes for tuning optical activity in conjugated polymers.

Stereoselective Plasmonic Interaction in Peptide-tethered Photopolymerizable Diacetylenes Doped with Chiral Gold Nanoparticles.

Designing polymeric systems with ultra-high optical activity is instrumental in the pursuit of smart artificial chiroptical materials, including the fundamental understanding of structure/property relations. Herein, we report a diacetylene (DA) moiety flanked by chiral D- and L-FF dipeptide methyl esters that exhibits efficient topochemical photopolymerization in the solid phase to furnish polydiacetylene (PDA) with desired control over the chiroptical properties. The doping of the achiral gold nanoparticles provides plasmonic interaction with the PDAs to render asymmetric shape to the circular dichroism bands. With the judicious design of the chiral amino acid ligand appended to the AuNPs, we demonstrate the first example of selective chiral amplification mediated by stereo-structural matching of the polymer-plasmonic AuNP hybrid pairs. Such ordered self-assembly aided by topochemical polymerization in peptide-tethered PDA provides a smart strategy to produce soft responsive materials for applications in chiral photonics.

Modulating the Chiroptical Response of Chiral Polymers with Extended Conjugation within the Structural Building Blocks.

Advancing the emerging area of chiral photonics requires modeling-guided concepts of chiral material design to enhance optical activity and associated optical rotatory dispersion. Herein, we introduce conformational engineering achieved by tuning polymer backbone conjugation through introduction of thiophene structural units in a chiral fluorene polymer backbone. Our theoretical calculations reveal a relationship between the structural conformation and the resultant rotational strength. We further synthesize a series of chiral fluorene-based polymers copolymerized with thiophene whose optical chirality trend is in qualitative agreement with predictions of our quantum chemical calculations. Varying the number of thiophene units in the monomer building block allows us to modulate the rotational strength by tuning the intrafibril helicity of single-stranded polymer chains, whereby the monomer conjugation is retained throughout the whole length of the polymer backbone. Our design concept delineates an underexamined approach: the concept of tuning backbone conjugation and helicity within the main chain to enhance the optical activity of chiral polymer systems.

Interposing layer of fibrin glue: A new horizon in vesico-vaginal fistula repair.

AIM: In this study our idea is to compare the effectiveness of using interposing layer of fibrin glue to omental flap in reducing the failure of laparoscopic vesicovaginal fistula repair. METHODS: Forty patients with fairly large vesicovaginal fistula were enrolled and divided in two groups of 20 each. We have used fibrin glue in one group and omental flap in the other group. RESULT: Of 20 patients in fibrin glue group no failure was seen, while 5 patients out of 20 in omental flap group had failure. CONCLUSION: This result is statistically significant and hence use of fibrin glue to be considered during laparoscopic repair of vesicovaginal fistulas.

Comparison of intravesical adjuvant therapy in bladder cancer with two different maintenance regimens of mitomycin and BCG.

OBJECTIVE: To compare recurrence rate and side effects with two different maintenance regimens of postoperative intravesical therapy with mitomycin and BCG in T1 bladder cancer. METHODS: Eighty were enrolled in this study and all received immediate post operative mitomycin. They were then allocated to two groups of 40, one group receiving intravesicle BCG and other a combination BCG and Mitomycin. They were followed up to a period of 2 years. RESULT: Two year recurrence rate after transurethral resection of bladder tumour with high grade T1 disease in the Combination group is low (20%) as compared to the BCG group (37.5%). CONCLUSION: Two year recurrences reduced with use of intravesical Mitomycin during maintenance in the combination group which though not statistically significant favours the trial with combination therapy in future studies. Side effect profile did not worsen with combination of Mitomycin and BCG.

Ultrafast carrier dynamics in 2D-2D hybrid structures of functionalized GO and CdSe nanoplatelets.

Considerable attention has been paid to designing graphene based 2D hybrid nanostructures for their potential applications in various areas from healthcare to energy harvesting. Herein, we have prepared 2D-2D hybrid structures of 2D CdSe nanoplatelets (NPLs) with thiol (-SH) functionalized reduced graphene oxide (G-Ph-SH). Microscopic and spectroscopic studies reveal that the G-Ph-SH surface is successfully decorated by CdSe NPLs through a thiophenol (-SH) linker. The significant photoluminescence quenching (65%) and the shortening of decay time from 1 ns to 0.4 ns of CdSe NPLs are observed after adding 100 µg of G-Ph-SH. Furthermore, the femto-second transient absorption spectroscopic (fs-TAS) study reveals that the growth time of CdSe NPLs in the composite is reduced to 0.4 ps from 0.8 ps due to faster hot electron cooling. A faster component of 1.4 ps in the kinetic parameters of the composite system further suggests that the ultrafast electron transfer occurs from the conduction band of CdSe NPLs to surface functionalized reduced graphene oxide. This type of 2D-2D hybrid structure may open up new possibilities in light harvesting applications.

Tuberculosis of the glans penis mimicking as carcinoma.

Penile tuberculosis (TB) is an uncommon variety of genitourinary TB. It is either primary (via local spread) or secondary (spread of infection from other organs). We encountered a case of rapidly growing penile ulceration, resembling carcinoma. Biopsy revealed the classic picture of TB, which responded well to antitubercular treatment.