3,140 research outputs found

    Micellization Behavior of Ionic Surfactants in Presence of Butanol Isomers in Non-aqueous Solutions

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    Electrical conductivity and surface tension measurements of various surfactants, such as sodium caprylate, sodium laurate, sodium palmitate and sodium stearate micellar solution,  containing  1-butanol  (1-BuOH),  2-butanol  (2-BuOH)  and tertiary butanol (t-BuOH) in n,n-dimethyl acetamide have been determined at various temperatures. Both methods show that micelles are formed in n,n-dimethyl acetamide  (DMA) solution in the presence of butanol isomers. Critical micelle concentration (cmc) has been determined for each of the surfactants. Critical micelle concentrations have also been measured as a function of temperatures and concentration of butanol isomers added. It is suggested that the addition of alcohol leads to an increase in n,n-dimethyl acetamide penetration into the micellar interface that depends on the alkyl chain configuration for three isomeric alcohols. Thermodynamic parameters of micellization, enthalpy  (ÄH0m,  entropy  (ÄS0m),  and free energy  (ÄG0m)  were determined from the temperature  dependence of  CMC.  The solvent composition dependence of these thermodynamic parameters is determined in terms of the effect of additives on the micellization of ionic surfactants. It is observed that both ÄH0m and ÄS0m bear out not only the observed order of decrease in cmc but also account reasonably the effects produced by differences in alkyl chain configuration for these isomeric alcohols. In all cases ÄG0m < 0, and remained practically constant over the entire solvent composition range studied.  It is suggested that due to different structural consequences of intermolecular interactions,  both enthalpy and entropy must differ in a  mutually compensating manner so that G0m is not significantly affected

    Antimicrobial resistance and Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) genotypes in N. gonorrhoeae during 2012-2014 in Karachi, Pakistan

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    Background: Globally, increasing antimicrobial resistance (AMR) in Neisseria gonorrhoea has led to decreased treatment options for gonorrhoea. Continuous monitoring of resistance is crucial to determine evolving resistance trends in Neisseria gonorrhoea and to suggest treatment recommendations. Quality assured gonococcal AMR data from Pakistan are mainly lacking. This study was performed to determine prevalence and trends of gonococcal AMR and molecular epidemiology of local strains during 2012-2014 in Karachi, Pakistan. Methods: Gonococcal isolates (n = 100) were obtained from urogenital specimens submitted to the Aga Khan University Laboratory, Karachi, Pakistan. Antimicrobial susceptibility was determined using Etest and molecular epidemiology was assessed by N. gonorrhoeae multiantigen sequence typing (NG-MAST). Quality control was performed using N. gonorrhoeae WHO reference strains C, F, G, K, L, M, N, O, and P, and ATCC 49226. Results: Susceptibility to spectinomycin, ceftriaxone and cefixime was 100 % and to azithromycin was 99 %. All isolates had low ceftriaxone MICs, i.e., ≤0.032 mg/L. Resistance to ciprofloxacin, tetracycline and penicillin G were 86 %, 51 % and 43 %, respectively. NG-MAST analysis identified 74 different sequence types (STs). Conclusions: A highly diversified gonococcal population, 74 NG-MAST STs (62 novel STs) with an increased resistance to penicillin G, ciprofloxacin and tetracycline circulated in Karachi, Pakistan. Fortunately, no resistance to ceftriaxone was detected. Accordingly, ceftriaxone can continuously be recommended as the treatment of choice. However it is recommended to increase the dose of ceftriaxone from 125 mg intramuscularly to 250 mg intramuscularly due to ceftriaxone MIC creep and emerging resistance reported in the region. Furthermore, due to the high level of resistance to ciprofloxacin (86 %) it is essential to exclude ciprofloxacin from the recommended first-line therapy. It is imperative to significantly broaden the gonococcal AMR monitoring with participation from other laboratories and cities in Pakistan

    FOXC1 (forkhead box C1)

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    Review on FOXC1 (forkhead box C1), with data on DNA, on the protein encoded, and where the gene is implicated

    Phylogenetic analysis of Artemisia L. (Asteraceae) based on micromorphological traits of pollen grains

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    The phylogenetic relationships within the genus Artemisia have been very controversial. In order to recognize the systematic inference of pollen grains in this genus, the micromorphological characteristics of pollens from 22 taxa were examined by means of light microscopy (LM) and scanningelectron microscopy (SEM). A phylogenetic analysis of Artemisia based on 9 micromorphological characters of pollens was conducted using Wagner parsimony method. In the resulting phylogenetic tree, relationships among different Artemisia species are shown. This study also presents thephylogenetic associations among 4 sections within the genus Artemisia. The reunion of genus Seriphidum with Artemisia was also confirmed
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