A novel microwave-assisted process is described for the rapid removal of catalytic
metal and non-desirable carbon impurities in fullerene, single wall, and multiple
wall carbon nanotube preparations. The purification process is carried out
at various programmed pressures, power levels and reaction times in a suspension
of the nanocarbon moieties in the presence of strong acids (for example, a mixture
of sulfuric acid and nitric acid), in weak acids (for example, acetic acid) and
in the presence of chelating agents (for example, EDTA - ethylenediaminetetraacetic
acid). In one embodiment, high metal removal efficiency of 70 to 90 % is observed.
The rapid increase in transaction-based e-services creates a challenge for firms: What combination of features should they offer to satisfy consumers while realistically considering operational and financial constraints? This article explores the above question by highlighting similarities and differences in consumer preferences between different segments for a transaction-based e-service. The study employs a Web-based discrete choice experiment, in which 1,430 consumers are offered e-service options, differing from each other in terms of non-web-based and online-only features, price per transaction, and marketing promotions. The results demonstrate that overall, consumer preferences for features of transaction-based e-services differ between offline and online consumers. Furthermore, with increase in consumer usage frequency, interesting trends regarding the relative importance for features are observed. Similarities also exist in consumer preferences between various usage-frequency-based consumer segments. The authors believe that these results have both managerial and research implications for design and operations strategy formulation for transaction-based e-services.
Ijaz, Farhana
Iqbal, Zafar
Rahman, Inayat Ur
Ali, Niaz
Qadir, Ghulam
Khan, M Azhar
ud-Din, Aziz
Shah, Abbas H
Ali, Imtiaz
Hussain, Saddam
Khan, Anees
Shah, Muzammil
Sadiq, Wasaf
Iqbal, Zafar
Lateef, Muhammad
Ashraf, Muhammad
Jabbar, Abdul
This paper describes the in vitro and in vivo anthelmintic activity of Artemisia brevifolia in comparison with levamisole. In vitro studies revealed anthelmintic effects of crude aqueous (CAE) and methanol extracts (CME) of Artemisia brevifolia (whole plant) on live Haemonchus contortus as evident from their paralysis and/or mortality at 6h post exposure. For in vivo studies, the whole plant of Artemisia brevifolia was administered as crude powder (CP), CAE and CME at graded doses (1, 2 and 3gkg−1 body weight (b.w.) to sheep naturally infected with mixed species of gastrointestinal nematodes. Maximum reduction (67.2%) in eggs per gram (EPG) of faeces was recorded on day 14 post treatment in sheep treated with Artemisia brevifolia CAE at 3gkg−1 b.w. It was found that, although, Artemisia brevifolia whole plant possesses anthelmintic activity against nematodes, it is not comparable with levamisole (99.2%reduction in EPG) at any of the doses tried in this study. However, increase in EPG reduction was noted with an increase in the dose of Artemisia brevifolia administered as CP, CAE and CME. The graded dose response suggested further studies on a larger number of animals on higher doses than those used in the current study.
Iqbal, Zafar
Masilela, Nkosiphile
Nyokong, Tebello
Lyubimtsev, Alexey
Hanack, Michael
Ziegler, Thomas
Photophysical and photochemical properties of a series of tetra- and octaglycosylated zinc phthalocyanines (ZnPcs) substituted with glucose and galactose moieties have been reported. Spectral properties of these phthalocyanines are compared in DMSO. Absorption spectra of the non-peripherally tetra- substituted ZnPcs 2 showed a significant red shift in their Q-band maxima as compared to the peripherally substituted analog 1. All the complexes gave high triplet quantum yields ranging from 0.68 to 0.88, whereas triplet lifetimes were in the range of 100-430 mu s in argon-saturated solutions. The octagalactosylated ZnPc 3b showed the highest triplet quantum yield and singlet oxygen quantum yield of 0.88 and 0.69, respectively. The fluorescence quantum yields and lifetimes of all the compounds under investigation were within the range of zinc phthalocyanine complexes.
Iqbal, Zafar
Lyubimtsev, Alexey
Herrmann, Timo
Hanack, Michael
Ziegler, Thomas
For the first time, octaglycosylated zinc(II) phthalocyanines in which the sugar part is protected by acetyl groups and the deprotected zinc(II) phthalocyanines were synthesized and characterized. The sugars glucose, galactose, lactose, cellobiose, and maltose are anomerically attached either via oxygen or sulfur to the phthalocyanine ring. The necessary starting materials for the syntheses of the phthalocyanines, the anomerically 4,5-diglycosylated phthalonitriles, were obtained by reacting the anomerically deprotected sugars containing OH and SH groups with 4,5-difluorophthalonitrile. The acetyl protected octaglycosylated phthalocyanines were obtained in yields between 55 and 78% by heating the anomerically 4,5-diglycosylated phthalonitriles in DMF with hexamethyldisilazane, p-toluenesulfonic acid, and zinc acetate. The acetyl groups in sugar moieties were removed to afford corresponding water-soluble phthalocyanines.
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