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An ion-imprinted polymer for the selective extraction of mercury(II) ions in aqueous media

  • Authors: Batlokwa, Bareki Shima , Chimuka, Luke , Tshentu, Zenixole R , Cukrowska, Ewa , Torto, Nelson
  • Date: 2012
  • Language: English
  • Type: Article
  • Identifier: vital:6566 , http://hdl.handle.net/10962/d1004125
  • Description: A double-imprinted polymer exhibiting high sensitivity for mercury(II) in aqueous solution is presented. Polymer particles imprinted with mercury(II) were synthesised by copolymerising the functional and cross-linking monomers, N’–[3– (Trimethoxysilyl)–propyl]diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS). A double-imprinting procedure employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer, was adopted. The imprinted polymer was characterised by FTIR, scanning electron microscopy (SEM) and the average size determined by screen analysis using standard test sieves. Relative selective coefficients (k`) of the imprinted polymer evaluated from selective binding studies between Hg2+ and Cu2+ or Hg2+ and Cd2+ were 10 588 and 3 147, respectively. These values indicated highly-favoured Hg2+ extractions over the 2 competing ions. The results of spiked and real water samples showed high extraction efficiencies of Hg2+ ions, (over 84%) as evaluated from the detected unextracted Hg2+ ions by ICP-OES. The method exhibited a dynamic response concentration range for Hg2+ between 0.01 and 20 μg/mℓ, with a detection limit (LOD, 3σ) of 0.000036 μg/mℓ (36 ng/ℓ) that meets the monitoring requirements for the USA EPA of 2 000 ng/ℓ for Hg2+ in drinking water. Generally, the data (n=10) had percentage relative standard deviations (%RSD) of less than 4%. Satisfactory results were also obtained when the prepared sorbent was applied for the pre-concentration of Hg2+ from an aqueous certified reference material. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre–concentration of mercury(II) ions in aqueous environments.
  • Full Text:
  • Date Issued: 2012

Cooperative wasp-killing by mixed-species colonies of honeybees, Apis cerana and Apis mellifera

  • Authors: Tan, K , Yang, M-Y , Li, H , Zhang, Z-L , Radloff, Sarah E , Hepburn, H Randall
  • Date: 2012
  • Language: English
  • Type: text , Article
  • Identifier: vital:6838 , http://hdl.handle.net/10962/d1010979 , http://dx.doi.org/10.1007/s13592-011-0098-5
  • Description: The cooperative defensive behaviour of mixed-species colonies of honeybees, Apis cerana and Apis mellifera, were tested against a predatory wasp, Vespa velutina. When vespine wasps hawk honeybees at their nest entrances, the difference in the numbers of bees involved in heat-balling among pure species and mixed-species colonies was not significantly different. However, in the mixed colonies, the numbers of A. cerana and A. mellifera workers involved in heat-balling were significantly different. The duration of heat-balling among these three groups was significantly different. During heat-balling, guard bees of both species in mixed colonies raised their thoracic temperatures and the core temperatures of the heat-balls were about 45°C, which is not significantly different from that of the pure species. These results suggest that the two species of honeybees can cooperate in joint heat-balling against the wasps, but A. cerana was more assertive in such defence.
  • Full Text: false
  • Date Issued: 2012

Mitochondrial DNA paradox: sex-specific genetic structure in a marine mussel despite maternal inheritance and passive dispersal

  • Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
  • Date: 2012
  • Language: English
  • Type: Article
  • Identifier: vital:6836 , http://hdl.handle.net/10962/d1010959
  • Description: Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.
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  • Date Issued: 2012

Network telescope metrics

  • Authors: Irwin, Barry V W
  • Date: 2012
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/427944 , vital:72475 , https://www.researchgate.net/profile/Barry-Ir-win/publication/265121268_Network_Telescope_Metrics/links/58e23f70a6fdcc41bf973e69/Network-Telescope-Metrics.pdf
  • Description: Network telescopes are a means of passive network monitoring, increasingly being used as part of a holistic network security program. One problem encountered by researchers in the sharing of the collected data form these systems. This is either due to the size of the data, or possibly a need to maintain the privacy of the Network address space being used for monitoring. This paper proposes a selection of metrics which can be used to communicate the most salient information contained in the data-set with other researchers, without the need to exchange or disclose the data-sets. Descriptive metrics for the sensor system are discussed along with numerical analysis data. The case for the use of graphical summary data is also presented.
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  • Date Issued: 2012

The distribution, habitat, diet and forensic significance of the scarab Frankenbergerius forcipatus (Harold, 1881) (Coleoptera : Scarabaeidae)

  • Authors: Midgley, John M , Collett, Isabel J , Villet, Martin H
  • Date: 2012
  • Language: English
  • Type: Article
  • Identifier: vital:6842 , http://hdl.handle.net/10962/d1010992
  • Description: Records of African beetles feeding on carrion are scattered and incomplete, but important to forensic entomology. Thirty-three specimens of Frankenbergerius forcipatus (Harold, 1881) were found on carrionnear Grahamstown, Eastern Cape, South Africa, providing new insight into the distribution (hills and mountains), habitat (fynbos and forest), biology (generalist on decaying material) and forensic significance (wet-decay, late opportunist) of the species.
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  • Date Issued: 2012

Academic Practices and Reasoning: APR 122

  • Authors: Scott, R , Blatchford, M
  • Date: 2012-01
  • Language: English
  • Type: Examination paper
  • Identifier: vital:18252 , http://hdl.handle.net/10353/d1011246
  • Description: Academic Practices and Reasoning: APR 122, supplementary examination January 2012.
  • Full Text: false
  • Date Issued: 2012-01

Data Structures and Algorithms: CSC 223

  • Authors: Scott, M S , Sibanda, K
  • Date: 2012-01
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17761 , http://hdl.handle.net/10353/d1010294
  • Description: Data Structures and Algorithms: CSC 223, degree examinations January 2012.
  • Full Text: false
  • Date Issued: 2012-01

Psychopathology and Counselling Psychology: PSY 311

  • Authors: Sandlana, N S , Marais, R , Young, C
  • Date: 2012-01
  • Language: English
  • Type: Examination paper
  • Identifier: vital:18016 , http://hdl.handle.net/10353/d1010593
  • Description: Psychopathology and Counselling Psychology: PSY 311, special examination January 2012.
  • Full Text: false
  • Date Issued: 2012-01

IsiXhosa Method: EDX 212

  • Authors: Mdaka, V N , Tyilo, P N
  • Date: 2011-08
  • Subjects: Xhosa language -- Study and teaching
  • Language: Xhosa
  • Type: Examination paper
  • Identifier: vital:18372 , http://hdl.handle.net/10353/d1011529
  • Description: IsiXhosa Method: EDX 212, Supplementary examination August 2011.
  • Full Text: false
  • Date Issued: 2011-08

Research Methodology: IPS 515

  • Authors: Samuel, M O , Berry, D M
  • Date: 2011-08
  • Subjects: Research -- Methodology
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17483 , http://hdl.handle.net/10353/d1010449
  • Description: Research Methodology: IPS 515, examination August 2011.
  • Full Text: false
  • Date Issued: 2011-08

A Practical Approach to Differential Calculus: MAT 112

  • Authors: Ndiweni, O
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17601 , http://hdl.handle.net/10353/d1009975
  • Description: A Practical Approach to Differential Calculus: MAT 112, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Advanced Programming: CSC 211

  • Authors: Chadwick, J , Sibanda, K
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17766 , http://hdl.handle.net/10353/d1010305
  • Description: Advanced Programming: CSC 211, degree examinatino June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Basic Chemistry: PAC 111F

  • Authors: Mbentse, J , Soyaya, S
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17833 , http://hdl.handle.net/10353/d1010387
  • Description: Basic Chemistry: PAC 111F, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Communication and Life Skills: CLS 111F

  • Authors: Scott, R , Formson, C
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:18316 , http://hdl.handle.net/10353/d1011440
  • Description: Communication and Life Skills: CLS 111F, examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Computer Architecture: CSC 212,

  • Authors: Chadwick, J , Ntuli, S
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17767 , http://hdl.handle.net/10353/d1010307
  • Description: Computer Architecture: CSC 212, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Introduction to Business Management: BEC 112F

Introduction to Computer Science: CSC 111F

  • Authors: Chifura, A , Ngwenya, S
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17764 , http://hdl.handle.net/10353/d1010303
  • Description: Introduction to Computer Science: CSC 111F, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Introduction to Computing and Programming Concepts: CSC 113

  • Authors: Ntuli, S , Sibanda, K
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17765 , http://hdl.handle.net/10353/d1010304
  • Description: Introduction to Computing and Programming Concepts: CSC 113, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Introduction to Remote Sensing: GIS 501

  • Authors: Tyson, C , Palmer, A R
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17913 , http://hdl.handle.net/10353/d1011144
  • Description: Introduction to Remote Sensing: GIS 501, Honours examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06

Mathematics Method: MAT 411

  • Authors: Bambiso, N P , Glover, H
  • Date: 2011-06
  • Language: English
  • Type: Examination paper
  • Identifier: vital:17607 , http://hdl.handle.net/10353/d1009982
  • Description: Mathematics Method: MAT 411, degree examination June 2011.
  • Full Text: false
  • Date Issued: 2011-06
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