Movement and Transformation of Selected Organic Pollutants in Subsurface Environmet in Arkansas

Several subsurface soil and groundwater samples from eastern, southern and central Arkansas were analyzed for chlorinated organic compounds commonly used as pesticides and industrial chemicals. No significant amount of these compounds were found in these samples. The adsorption/partition characteristics of some of these compounds, such as dichlorophenols, aldrin and endrin, were determined in siltloam, sandyloam and clay soils collected from the above geographical locations. Results indicate that there is considerable difference in retention capability of different types of soils with respect to different pollutants. The partition coefficient of a particular compound in a certain type of soil can be related to both the pH and the organic matter content of the soil

A Systematic Study to Reduce Trihalomethane Precursors in Little Rock Drinking Water by Combined Alum Coagulation-Powdered Activated Carbon Treatment

Studies have been conducted to evaluate powdered activated carbon (PAC) as an agent for controlling trihalomethanes in drinking water. Laboratory studies indicate that PAC is highly efficient in removing free trihalomethanes in water within a few hours. The removal efficiency of humic acid, a known THM precursor, by PAC is considerably less. However, longer treatment time can remove the precursors quite significantly. Humic substances in surface water samples can also be removed by PAC

Electrochemistry of Dihalogenated Nicotonic Acids in Aqueous and Aprotic Media

The electrochemical reduction of several 2,5- and 5,6- dihalonicotinic acids have been studied in dimethyl sulfoxide as well as in aqueous buffers of different pH. The polarographic half-wave potentials for the reduction of these compounds in both media are reported here. The compounds appear to reduce at the carboxyl group. The presence of halogen atoms on the pyridine ring facilitates reduction

Analysis of a Mixture of Several Dihalonicotinic Acids by Gas Chromotography and Gas Chromotography-Mass Spectrometry

Six 2,5- and 5,6- dihalonicotinic acids in a mixture were converted to their corresponding methyl esters and then analyzed by gas chromatography and gas chromatography-mass spectrometry. Four methods of conversion were compared for their GC sensitivity, efficiency and analysis time. In Method #1, using HC1 and methanol as the reagents, the displacement of the halogens by chlorine (from HC1) at 2- and 6-positions was a common occurrence, rendering the method inefficient. In Method #2 (BF3/methanol), the displacement of halogens by methoxide was evident. Method #3 (dicyclohexylcarbodiimide/methanol) produced a mixture of derivatives with a poor yield. Method #4 (diazomethane) gave a quantitative yield of the corresponding methyl esters without any side reactions and was suitable for analytical method development. The latest method provided short analysis time with all six methyl dihalonicotinates eluting within nineteen minutes. The resolution of the ester peaks was excellent and the detection limit was about 1ng/|Mu L for the dihalonicotinic acids

Oxidation-Reduction Characteristics of Chlorophenols in an Aprotic Medium

Eighteen chlorophenols, containing from one to five chlorine atoms on the benzene ring at various positions, have been studied by cyclic voltammetric methods to evaluate their oxidation-reduction characteristics in an aprotic medium. The compounds were dissolved in dimethylsulfoxide containing 0.10 M tetrabutylammonium perchlorate as the supporting electrolyte and were then both oxidized and reduced on a glassy carbon electrode. The results indicate that phenols oxidize in a one-step process to phenoxium ion which dimerizes to quinone ether. The ether can be reduced back to phenol in a two-step reduction process. The oxidation potential of the chlorophenols varies with the number and the position of the chlorine substitution. It may also have a relationship with the toxicity of the compound. The main purpose of this study is to understand low chlorophenols, classified as environmental pollutants for their toxicity and carcinogenicity, are oxidized by cytochrome P450 in the metabolic activation process in living systems

In-vitro Antibacterial, Antifungal and cytotoxic activity of cobalt (II), copper (II), nickel (II) and zinc (II) complexes with furanylmethyl- and thienylmethyl-dithiolenes: [1, 3-dithiole- 2-one and 1,3-dithiole-2-thione]

Some antibacterial and antifungal furanylmethyl-and thienylmethyl dithiolenes and, their Co(II), Cu(II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative; Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella flexeneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureus bacterial strains, and for in-vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. All compounds showed significant antibacterial and antifungal activity. The metal complexes, however, were shown to possess better activity as compared to the simple ligands. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties

Outcome of adult patients with acute lymphoblastic leukaemia receiving the MRC UKALL XII protocol: a tertiary care centre experience

Introduction:Acute lymphoblastic leukaemia (ALL) is a heterogeneous group of lymphoid neoplasm resulting from the proliferation of malignant lymphoid cells. We aimed to study the outcome of adult Patients with ALL receiving the Medical Research Council UKALL XII protocol. Methods: This was a retrospective study conducted at Aga Khan University Hospital from January 2001 to December 2008. The medical records of all adult Patients were reviewed and analysed for clinical, morphological and immunological features at presentation and impact on treatment outcomes. Multivariate analysis and survival studies were performed using Kaplan-Meier statistics. Results: The total number of Patients was 54, with a male to female ratio of 3.4:1 and a median age of 28 years. Common presenting symptoms were fever (n is 49) and bleeding (n is 14). 38 Patients had haemoglobin less than 10 gms/dl, 21 had white blood cell (WBC) count of 50 x 10E9/L or more, and 35 had lactate dehyrogenase more than 1,000 IU. Morphologically, FAB-L2 was the commonest subtype, with 38 Patients with B-ALL and eight with T-ALL. Multivariate analysis showed that age above 30 years, male gender, WBC count above 50 x 10E9/L and T-ALL subtype were independent risk factors for poor survival. 46 (85 percent) Patients achieved complete remission. The median survival was 12.3 months. At the end of five years, 16 Patients were alive, two were alive with disease and 14 were in complete remission. Conclusion: Overall survival and relapse rates in our study were comparable to those reported internationally

Hammett Correlations of Half-Wave Reduction Potentials in a Series of N-(Aryl substituted)-Dichloronicotinamides

Excellent correlations of Hammett substituent constants (sigmaR) of a series of N-(R-substituted aryl) -2,6-, 2,5-, and 5,6- dichloronicotinamides with polarographic half-wave potentials were observed. Although the correlations demonstrate that all three series of amides experience comparable sensitivity to the R groups at the carbonyl reduction site, the relative ease of reduction varies according to the chlorine substitution pattern on the pyridine ring. These differences are suggested to be due to combinations of mesomeric, inductive, and field effects which operate differently in the three systems. Correlation analysis also revealed that Hammett heteroatomic replacement constants previously determined by NMR studies are valid in the present polarographic studies

Antibacterial, antifungal and cytotoxic properties of novel N-substituted sulfonamides from 4-hydroxycoumarin

A new series of 4-({[2, 4-dioxo-2H-chromen-3 (4H)-ylidene] methyl} amino) sulfonamides have been obtained by the condensation reaction of 4-hydroxycoumarin with various sulfonamides (sulfanilamide, sulfaguanidine, p-aminomethyl-sufanilamide, p-aminoethylsufanilamide, sulfathiazole, sulfamethoxazole, sulfamethazine and 4-[(2-amino-4-pyrimidinyl) amino] benzenesulfonamide) in the presence of an excess of ethylorthoformate. These compounds were screened for their in-vitro antibacterial activity against four Gram-negative (E. coli, S. flexneri, P. aeruginosa and S. typhi) and two Gram-positive (B. subtilis and S. aureus) bacterial strains and for in-vitro antifungal activity against T. longifusus, C. albicans, A. flavus, M. canis, F. solani and C. glaberata. Results revealed that a significant antibacterial activity was observed by compounds (4) and (5), (6) and (8) against two Gram-negative, (P. aeruginosa and S. typhi) and two Gram-positive (B. subtilis and S. aureus) species, respectively. Of these (4) was found to be the most active. Similarly, for antifungal activity compounds (3) and (8) showed significant activity against M. canis and, (6) and (8) against F. solani. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties and only two compounds, (4) and (8) possessing LD50 = 2.9072 x 10(-4) and 3.2844 x 10(-4) M, respectively, displayed potent cytotoxic activity against Artemia salin