Predictions on Structural and Electronic Properties to Synthesize Bismuth-Carbon Compounds in Different Periodicities

This work was carried out to explore the compounds of bismuth with carbon using density functional theory (DFT)-based computations. The structures of the compounds BiC, BiC₂, BiC₃, Bi₂C₃, BiC₅, and Bi₂C₅ were predicted at a generalized gradient approximation (GGA-PBE) level of theory. The calculations were carried out on the structures in unit cell and supercell geometries in slab and bulk periodicities. The structural and electronic properties of the mentioned compounds were investigated in detail. The calculations of the structures revealed lattice constants of the compounds for cubic unit cell as 212.2 pm for BiC, 176.9 pm for BiC₂, 240.5 pm for BiC₃, 232.4 pm for Bi₂C₃, and 354.5 pm for Bi₂C₅. The compounds BiC, BiC₂, BiC₃, BiC₅, and Bi₂C₅ were found to be metallic, whereas Bi₂C₃ exhibited semiconducting character with a band gap of 0.305 eV. This work provides an initial framework for preparing new 2D materials from Bi_xC_y.     

Alkali halides as nucleophilic reagent sources for N-directed palladium-catalysed ortho-C–H halogenation of s-tetrazines and other heteroaromatics

A general palladium-catalysed selective C–H halogenation reaction is reported, which was successfully achieved for a large variety of functionalized aromatic rings incorporating diverse N-directing groups. By using simple alkali halides of MX type as the nucleophilic reagent source (M = Li, Na, K, Cs and X = I, Br and Cl), and phenyliodanediacetate oxidant, clean C–H-iodination, bromination and chlorination reactions were performed. This general protocol of selective ortho-monohalogenation, which complements but contrasts with the classical methods using electrophilic reagents, is achievable in a short time (30 min) with microwave irradiation assistance. The reaction was extended to substrates bearing N-directing pyridine, pyrimidine, pyrazole, oxazoline, naphtho[1,2-d]thiazole, and azobenzene groups. Notably, the topical and selectivity-challenging s-tetrazine, as a nitrogen-rich heteroaromatic, was successfully halogenated by this protocol.

A general palladium-catalysed selective C–H halogenation reaction is reported, which was successfully achieved for a large variety of functionalized aromatic rings incorporating diverse N-directing groups.     

Dispensing habits of Johannesburg pharmacists in treating acute infantile diarrhoea

Sixty pharmacists in Johannesburg were randomly selected and questioned on their suggested treatment of acute infantile diarrhoea as well as their knowledge of oral rehydration therapy (ORT); 53 (88%) responded. Of 51 pharmacists who had treated diarrhoea in children, 8 (16%) had never heard of ORT, while 20 (39%) treated this condition with antidiarrhoeal drugs. These findings are perturbing, because acute diarrhoeal disease is the biggest cause of mortality of children aged 1-4 years in South Africa and ORT is recognised as an effective means of prevention of death.     

Kala-azar in Zambia: first report of two cases

Two autochthonous cases of kala-azar, the first such report of the disease from Central and Southern Africa, are described. Both patients presented with generalized macules, papules and nodules without ulceration and both also had tuberculosis. Amastigotes were cultured from blood and identified in skin, bone marrow, liver and spleen.     

The sulfone syndrome secondary to dapsone prophylaxis in a patient undergoing unrelated hematopoietic stem cell transplantation

Dapsone is commonly used for pneumocystis carinii pneumonia (PCP) prophylaxis in immunocompromised patients. It has been used as an alternative therapy in the hematopoietic stem cell transplant (HSCT) setting in patients who can't tolerate trimethoprim-sulfamethoxazole. The Sulfone syndrome is not a well-known sequela of dapsone therapy and occurs at various doses, ranging from 50-300 mg/d. In all cases the syndrome occurs within 2 months of initiating therapy. Its clinical manifestations include: fever, methemoglobinemia, hemolytic anemia, exfoliative dermatitis and transaminits. A 51-year old female underwent a matched unrelated hematopoiectic stem cell transplant for acute mylogenous leukemia. Dapsone therapy was initiated on day +28 at a dose of 100 mg/day for PCP prophylaxis secondary to the patient's history of a sulfonamide allergy. On day +59, one month after initiation of therapy she developed hepatitis, hemolytic anemia, fever and methemoglobinemia of 8%. She was transferred to the intensive care unit and subsequently developed an exfoliative dermatitis. We conclude that the clinical presentation of this patient after HSCT on dapsone therapy coincide with the sulfone syndrome not previously described in a patients after HSCT.     

Penicillinase-producing gonococcal strains in Zambia. Observations on treatment failures

Penicillinase-producing strains of Neisseria gonorrhoeae (PPNG) were detected in nine out of 27 (3.2%) treatment failures in 310 cases of acute gonococcal urethritis in men in Lusaka, Zambia. Minimum inhibitory concentrations of penicillin for 17.2% of 233 gonococcal isolates were less than or equal to 0.05 microgram/ml, for 38.2% between 0.125 and 0.25 microgram/ml, and for 46.6% greater than or equal to 0.5 microgram/ml. At present the prevalence of PPNG in African countries is not known but is likely to increase rapidly unless simplified control schemes are adopted within the existing health care programmes. Endemic pockets of PPNG in a few countries can threaten worldwide efforts to control gonorrhoea.