[en] Present study was aimed to develop a reproducible, cheap and sensitive method for silver staining of double stranded DNA in agarose gel. Study Design: Experimental, repeated measure design. Place and Duration of Study: Department of Genetics, University of Karachi, Karachi. This experimental study was conducted, from Nov 2013 to Jan 2014. Material and Methods: The new method is the modification and improvement in the original method proposed in the literature. Samples of ds genomic DNA was run on a nondenaturing 1.5% agarose/0.5X TBE. After electrophoresis gel was fixed in 10% acetic acid and staining was performed using 1 gm % silver nitrate. DNA bands were developed using 1.5% NaOH. At each step shaking was done manually with a circular movement. The modified method was also compared with the ethidium bromide staining of the same samples of DNA. Results: The modified method was proved to be as sensitive as the ethidium bromide with the advantage of having long term conservation ability of the gel. The main advantage of the protocol is the consumption of far less concentrations of silver nitrate and sodium hydroxide and the avoidance of the use of sodium thiosulphate. Conclusion: This method was easily reproducible, sensitive, and cheap with improved conservation ability of gel. It also avoids use of hazardous, expensive and time consuming radioactive and fluorescent detection. (author)

[en] Balloon dilatation of Primary Achalasia Cardia (PAC) is usually performed under antegrade endoscopic guidance, with conscious sedation. The main goals of this prospective study were to assess the safety and efficacy of pneumatic dilatation without conscious sedation and to determine the endoscopic signs of effacement of the balloon waist. Pneumatic dilatation was successfully performed as outdoor procedure without conscious sedation in patients (n= 25; mean age 42.56 years) with endoscopic and radiologic diagnosis of PAC. Immediate relief of symptoms was observed in 23 (92%) cases. Effacement of the balloon waist under endoscopic vision was appreciated in all cases in the present study. Common complications of pneumatic dilatation were chest pain in all (100%) subjects and mild local bleeding in 17 (68%) patients. There was no cancellation of procedure. Re-dilatation was required in 2 (8%) cases. The duration of follow-up was from 6 weeks to 23 months. Pneumatic dilatation of PAC can be safely performed as same day procedure, without conscious sedation. Obliteration of the balloon waist can be readily determined by antegrade endoscopic assessment of stretch on the lower oesophageal sphincter (EASL). (author)

[en] Dipolar Imidazoanthraquinone based molecules (AQ01 and AQ02) were synthesized and characterized. Photophysical and solvatochromic studies suggested polar nature for these materials. The potential of these molecules as an electron acceptor was deduced by the quenching experiments with the commonly used electron donor poly-3-hexylthiophene (P3HT) in bulk heterojunction (BHJ) solar cells.Density functional theory (DFT) based theoretical calculations gave insight on the dipolar nature, H-bonding and π-π interaction in different types of supramolecular assemblies of AQ01 and AQ02. Calculations anticipated that in AQ01 π-π interaction via anti-parallel orientation is favored energetically. Morphological studies on thermally evaporated thin films indicated interconnected nano-assemblies in AQ01 while random aggregates in AQ02. Molecules AQ01/ AQ02 were blended with P3HT and charge transport properties of these molecules were estimated. Hole mobility in AQ01 based device was found to be as high as 2.4 x 10^-4 cm²/Vs. Our results signifies the potential of dipolar molecule AQ01 as a non-fullerene based electron acceptor in. BHJ solar cell devices. (author)

[en] Acridone (acceptor) and naphthylamine (donor) based Donor-Acceptor-Donor (D-A-D) compound (1) was synthesised, characterised and its thermally-activated delayed fluorescence (TADF) properties were studied in detail. Compound 1 is fluorescent and emits in the green region (550 nm). The energy gap between the ground and the lowest excited singlet (S₁) state is estimated to be 2.55 eV. The energy gap between the CT singlet and triplet states (∆E_ST) was found to be ~0.3 eV. Small ∆E_S1-T1 is one of the important criteria for TADF to take place in a molecule and thus detailed photophysics has been studied. Transient lifetime measurements showed an increase in the fluorescence lifetime (τ) on purging with N₂, as compared with that in air-saturated solution, indicating the involvement of the triplet state in emission. Emission at 550 nm was also observed with a delay of 100 µs which corresponded to the delayed fluorescence in 1. The lifetime of TADF was found to be 176 µs. Applications of TADF materials in organic light-emitting devices (OLEDs) has gotten attention as TADF materials utilise the triplet excitons which helps in increasing internal quantum efficiency of device. Air-saturated based on 1 were fabricated and their intensity was found to be nearly as high as 17,000 Cd/m² at 25 mA/cm² which was comparable to many of the known TADF emitters.

Graphic abstract

Acridone-amine derivatives was synthesized and its photophysical properties were carried out to establish TADF. It was also used in fabrication of OLEDs. .