A stability-indicating high performance liquid chromatographic (HPLC) assay for the simultaneous determination of atorvastatin and amlodipine in commercial tablets
- Authors: Mohammadi, Ali , Rezanour, N , Ansari Dogaheh, M , Ghorbani Bidkorbeh, F , Hashem, M , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6403 , http://hdl.handle.net/10962/d1006340
- Description: A simple, rapid, precise and accurate isocratic reversed-phase stability-indicating HPLC method was developed and validated for the simultaneous determination of atorvastatin (AT) and amlodipine (AM) in commercial tablets. The method has shown adequate separation for AM, AT from their associated main impurities and their degradation products. Separation was achieved on a Perfectsil® Target ODS-3, 5 μm, 250 mm × 4.6 mm i.d. column using a mobile phase consisting of acetonitrile–0.025 M NaH2PO4 buffer (pH 4.5) (55:45, v/v) at a flow rate of 1 ml/min and UV detection at 237 nm. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The linearity of the proposed method was investigated in the range of 2–30 μg/ml (r = 0.9994) for AT and 1–20 μg/ml (r = 0.9993) for AM. The limits of detection were 0.65 μg/ml and 0.35 μg/ml for AT and AM, respectively. The limits of quantitation were 2 μg/ml and 1 μg/ml for AT and AM, respectively. Degradation products produced as a result of stress studies did not interfere with the detection of AT and AM and the assay can thus be considered stability-indicating.
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- Date Issued: 2007
Quality of life in South Africa: the first ten years of democracy
- Authors: Moller, Valerie
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7110 , http://hdl.handle.net/10962/d1010741
- Description: South Africa celebrated ten years of democracy in 2004. This special issue of Social Indicators Research (SIR) reviews developments that have impacted on the quality of life of ordinary South Africans during the transition period. The issue updates an earlier volume of SIR (Volume 41) published in 1997 and as a stand-alone volume. The earlier volume was initiated following SIR editor Alex Michalos’ first visit to South Africa. This update on quality of life in South Africa follows on his return visit to the country in 2004 to see firsthand the changes that had occured in the meantime. This introductory article outlines major achievements of and setbacks for the new democracy and the challenges facing it in future. It provides the backround for the evaluations of a range of quality of life domains and issues including poverty and inequality, crime, the HIV/AIDS epidemic, migration and housing, religiosity, reconciliation, and optimism for the future which are covered in the eleven articles that follow. The introduction divides the articles under the headings of challenges, achievements, monitoring quality of life, and social capital for the future. The overview article concludes that improvements in quality of life have been uneven but goodwill and a positive outlook bode well for South African quality of life in future.
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- Date Issued: 2007
Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, P K
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
- Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
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- Date Issued: 2007
Using the tutorial system to improve the quality of feedback to students in large class teaching
- Authors: Snowball, Jeanette D , Sayigh, E
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70848 , vital:29752
- Description: In many universities, economics teachers now face the challenge of dealing with large, diverse classes, especially at undergraduate level. A common concern is the non-attendance at lectures of unmotivated (conscript) students. This paper presents the results of a student assessment of a macroeconomics 1 course, coupled with a self-assessment of their own input into the course. The results obtained, using an econometric model, suggest that what students do outside of lectures is equally, or more, important than lecture attendance itself. The paper concludes by examining the possibility of using peer assessed group learning as a feasible way to encourage deep learning in large classes.
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- Date Issued: 2007