A Novel One Pot Synthesis of o‐Nitrophenylacetic Acid and Unexpected p‐Nitrobenzoic Acid by HNO3‐Mediated CH2 Extrusion Reaction of Phenylacetic Acid

The HNO₃‐mediated CH₂ extrusion reactions of phenylacetic acid lead to one pot synthesis of unexpected commercially important product 4‐nitrobenzoic acid through the formation of 4‐nitrophenylacetic acid and 2‐nitrophenylacetic acid.     

Effect of transmission fiber and amplifier noise on optical chaos synchronization

Optical chaos propagation has few constraints peculiar to itself which do not become as significant in conventional nonchaotic optical communication. We have investigated the effects of transmission fiber nonlinearities, dispersion and noise of erbium doped fiber amplifier (EDFA) on chaotic signal synchronization in lumped and distributed configuration. It is found that the effects of fiber dispersion can be easily compensated; however, the effects of fiber nonlinearity on chaos cannot be overdone and must be avoided. Three distinct configurations with different combinations of standard telecommunication fiber, dispersion compensation fiber and lumped and distributed EDF for amplification are analysed. The results are compared in terms of sync diagrams and noise figure. The chaos after propagation through distributed amplification performs better as compared to lumped amplification. Also, a new quantitative measure for the calculation of deviation in sync diagram of chaos is introduced.     

Dual-path handheld system for cornea and retina imaging using optical coherence tomography

Optical Review - A dual-path handheld system is proposed for cornea and retina imaging using spectral domain optical coherence tomography. The handheld sample arm is designed to acquire two images...     

Synthesis,characterisation and supramolecular interaction of Rh-biphenylic-imidazole-phenanthroline with antibiotics

A novel rhodium biphenylic imidazole phenanthroline metal-organic complex (BIP-MC) has been synthesised and characterised as a stable supramolecule. The structure of compound was established on the basis ESI, ¹H NMR and UV–vis spectroscopic data. The selectivity of BIP-MC as a new fluorescent chemosensor for various antibiotics has been explored. The supramolecular interaction of amoxicillin with BIP-MC enhanced the fluorescence activity of BIP-MC. A linear response of the sensor was observed in the measuring ranges of excitation 240–298 nm and emission 290–360 nm with detection limits of up to 10 μg/ml at an optimum pH 8.0. Based on the observations made here, a new quantitative method for the determination of this drug in synthetic samples without the use of separation of matrix is developed. It is also inferred that the possible fluorescence enhancement is due to the formation of exciplex between the BIP-MC and amoxicillin. These finding will thus help in pharmacokinetics studies of drugs. The sensor was used for the direct assay of amoxicillin antibiotic in commercial pharmaceutical preparations.     

Regioselective Synthesis of Trichloromethyl‐Substituted Salicylates and Cyclohexenones by One‐Pot Cyclizations of 1,3‐Bis(trimethylsilyloxy)buta‐1,3‐dienes

A variety of 6‐(trichloromethyl)salicylates (=2‐hydroxy‐6‐(trichloromethyl)benzoates) were prepared by TiCl₄‐mediated cyclization of 1,3‐bis(trimethylsilyloxy)buta‐1,3‐dienes with 1,1,1‐trichloro‐4,4‐dimethoxybut‐3‐en‐2‐one. The employment of trimethylsilyl trifluoromethanesulfonate (Me₃SiOTf) as Lewis acid resulted in the formation of trichloromethyl‐substituted cyclohexenones. The cyclizations proceeded with good‐to‐very‐good regioselectivities.     

Micellar Enhanced Ultrafiltration of Reactive Black 5 from Aqueous Solution by Cationic Surfactants

Reactive black 5 (RB-5) dye was removed from a water stream using two cationic surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC), via micellar enhanced ultrafiltration. Three membranes with different pore size were used for the determination of rejection coefficient and permeate flux of the solution at 1.5 bar trans-membrane pressure (TMP). The two surfactants (CPC and CTAB) played an almost negligible role in rejection efficiency with 5000 and 10,000 molecular weight cut-off membrane (MWCO), respectively. In this case, high rejection and low permeate flux was the result of a larger molecular size of RB-5 DYE being retained by comparatively smaller sized pores of membrane via ultrafiltration. However, CPC and CTAB surfactants showed 83% and 98% rejection coefficient, respectively, at a concentration greater than their CMC values against 30,000 MWCO. Permeate flux remained low and constant in presence of 5000 and 10,000 MWCO with a small variation against 30,000 MWCO for the two surfactants, thereby no appreciable effect on both surfactant concentrations on concentration polarization was estimated. Thus, RB-5 dye alone was determined to be responsible for membrane plugging or concentration polarization and ultimately for low permeate flux. The effect of trans-membrane pressure was also investigated during this study.