Kinetics and equilibrium adsorption study of lead(II) onto activated carbon prepared from coconut shell

Removal of lead from aqueous solutions by adsorption onto coconut-shell carbon was investigated. Batch adsorption experiments were performed to find out the effective lead removal at different metal ion concentrations. Adsorption of Pb2+ ion was strongly affected by pH. The coconut-shell carbon (CSC) exhibited the highest lead adsorption capacity at pH 4.5. Isotherms for the adsorption of lead on CSC were developed and the equilibrium data fitted well to the Langmuir, Freundlich, and Tempkin isotherm models. At pH 4.5, the maximum lead adsorption capacity of CSC estimated with the Langmuir model was 26.50 mg g(-1) adsorbent. Energy of activation (Ea) and thermodynamic parameters such as DeltaG, DeltaH, and DeltaS were evaluated by applying the Arrhenius and van't Hoff equations. The thermodynamics of Pb(II) on CSC indicates the spontaneous and endothermic nature of adsorption. Quantitative desorption of Pb(II) from CSC was found to be 75% which facilitates the sorption of metal by ion exchange.

A Facile Synthesis of Naphthyl-Quinolyl Ethanes and Chromenyl-Quinolyl Ethanes

The reaction of alkaline 2,4-dihydroxyquinoline 1 and 1-tetralone 2 in 2% sodium hydroxide solution with vinyl acetate afforded a brown solid 3, which on treatment with phosphorous oxychloride yielded 2,4-dichloro-3-[l’-(l-chloro-naphth-2-yl)ethyl]quinoline (4). The same reaction of 1 and chromanone 7 with vinyl acetate afforded 2,4-dichloro-3-[l’-(4-chloro- 2-methyl-chromen-3-yl)ethyl]quinoline (9)

Synthesis of some novel 2-oxo-pyrano(2,3-b)- and 2-oxo-pyrido(2,3-b)quinoline derivatives as potential antimalarial, diuretic, clastogenic and antimicrobial agents

The 2-chloro-3-formyl quinoline derivatives (1a-e) on treatment with acetic anhydride and sodium acetate, afforded the corresponding novel 2-oxopyrano(2,3-b) quinoline derivatives (2a-e), and these were subjected to ammonia treatment to yield the corresponding naphthyridine derivatives (3a-e). The prepared compounds (2a-e) were tested for their antimalarial, diuretic, clastogenic and antimicrobial properties. Not all the compounds showed a diuretic effect and the significant increase in the frequency of micronuclei shows that they are non-clastogens, whereas the 7-chloro derivative (2e) was a very effective antimalarial agent against the mosquito species. All the compounds were found to have optimum antimicrobial activity against Staphylococcus aureus, Escherichia coli and Salmonella typhi. Compounds 2d and 2e were found to be most active against the bacteria tested.

Quinoline Alkaloids: Synthesis of Pyrano

Polyphosphoric acid (PPA)-catalyzed cyclization of 2-ono-3-vinylquinolinecarboxylic acid (1) yielded 3,4-dihydro-2,2-dimethyl-2H-pyrano[2,3-b]quinoline (4). The same reaction of 4-methoxy-2-oxo-3-vinylquinolinecarboxylic acid (1g) afforded 4-methoxy-2,2-dimethylpyrano[2,3-b]quinoline (4g), which on hydrolysis with ethanolic hydrochloric acid gave khaplofoline (5). The Prevost reaction of 4-methoxy-3-prenylquinolin-2-one (6) using I2/HgO in acetic acid yielded 4-methoxy-2-isopropylfuro[2,3-b]quinoline (7). Compound 7 on reduction with H2/Pd-C followed by N-methylation and de-O-methylation afforded lunacrine (10a). A similar reaction sequence on 6b gave demethoxylunacrine (10b).

Predicting difficult intubation--a comprehensive scoring system

A study was conducted in an attempt to devise a simple and more accurate method of predicting difficult intubation. Prospective assessments were made in 282 patients and retrospective assessment in 16 patients with regard to 21 anatomical factors which were correlated with the laryngoscopic view at intubation. Twelve factors correlated significantly with difficult intubation. Four of these were eliminated after multifactorial analysis. A scoring system was devised, assigning points to each variable based on its discriminative value. A score of 6 or more correctly identified 22 out of the 23 difficult intubations and there were 50 false positives (sensitivity, specificity and PPV of 96%, 82% and 31% respectively). When negative scoring was done for factors favouring easy intubation, false positives were reduced to 36, but only 20 difficult cases could be identified correctly.

Myelosuppression associated with azathioprine-allopurinol interaction after heart and lung transplantation

It is widely recommended that, during concurrent therapy with allopurinol, the azathioprine dosage should be decreased by at least two thirds. We retrospectively studied compliance with this guideline in 24 patients who had commenced allopurinol at a median of 33 months (range, 2-145 months) after heart and/or lung transplantation. The median reduction in azathioprine dose at initiation of allopurinol was 73.3% but ranged from 0% to 90% (>67% in 14 patients). Within 3 months, 11 (46%) of the patients became leukopenic (white blood cell count <4 x 10(9)/L), 7/23 (30%) became moderately anemic (hemoglobin <10 g/dl), and 5/23 (22%) became thrombocytopenic (platelets <150 X 10(9)/L). Decreasing the dose of azathioprine by two thirds or greater reduced but did not abolish the risk of myelotoxicity. These data highlight the need for close hematological monitoring of patients treated with this drug combination. Agents other than allopurinol should be considered for treating hyperuricemia after thoracic organ transplantation.