1H NMR-based kinetic-mechanistic study of the intramolecular trans-esterification of 2-exo-3-exo-dihydroxybornane monoacrylate esters
- Duggan, Andrew R, Mciteka, Lulama P, Lobb, Kevin A, Kaye, Perry T
- Authors: Duggan, Andrew R , Mciteka, Lulama P , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448871 , vital:74767 , xlink:href="https://hdl.handle.net/10520/EJC135616"
- Description: A 1H NMR study of the acid-catalyzed, intramolecular trans-esterification between isomeric 2-exo-3-exo-dihydroxybornane monoacrylate esters has afforded insights into the reaction mechanism and permitted the determination of kinetic and thermodynamic parameters for the pseudo-first-order processes.
- Full Text:
- Date Issued: 2013
- Authors: Duggan, Andrew R , Mciteka, Lulama P , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448871 , vital:74767 , xlink:href="https://hdl.handle.net/10520/EJC135616"
- Description: A 1H NMR study of the acid-catalyzed, intramolecular trans-esterification between isomeric 2-exo-3-exo-dihydroxybornane monoacrylate esters has afforded insights into the reaction mechanism and permitted the determination of kinetic and thermodynamic parameters for the pseudo-first-order processes.
- Full Text:
- Date Issued: 2013
A dynamically weighted multi-modal biometric security system
- Brown, Dane L, Bradshaw, Karen L
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473684 , vital:77672 , xlink:href="https://www.researchgate.net/publication/315839228_A_Dynamically_Weighted_Multi-Modal_Biometric_Security_System"
- Description: The face, fingerprint and palmprint feature vectors are automatically extracted and dynamically selected for fusion at the feature-level, toward an improved human identification accuracy. The feature-level has a higher potential accuracy than the match score-level. However, leveraging this potential requires a new approach. This work demonstrates a novel dynamic weighting algorithm for improved image-based biometric feature-fusion. A comparison is performed on uni-modal, bi-modal, tri-modal and proposed dynamic approaches. The proposed dynamic approach yields a high genuine acceptance rate of 99.25% genuine acceptance rate at a false acceptance rate of 1% on challenging datasets and big impostor datasets.
- Full Text:
- Date Issued: 2016
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473684 , vital:77672 , xlink:href="https://www.researchgate.net/publication/315839228_A_Dynamically_Weighted_Multi-Modal_Biometric_Security_System"
- Description: The face, fingerprint and palmprint feature vectors are automatically extracted and dynamically selected for fusion at the feature-level, toward an improved human identification accuracy. The feature-level has a higher potential accuracy than the match score-level. However, leveraging this potential requires a new approach. This work demonstrates a novel dynamic weighting algorithm for improved image-based biometric feature-fusion. A comparison is performed on uni-modal, bi-modal, tri-modal and proposed dynamic approaches. The proposed dynamic approach yields a high genuine acceptance rate of 99.25% genuine acceptance rate at a false acceptance rate of 1% on challenging datasets and big impostor datasets.
- Full Text:
- Date Issued: 2016
A heavy-atom-free π-extended N-confused porphyrin as a photosensitizer for photodynamic therapy
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
- Date Issued: 2021
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
- Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
- Full Text:
- Date Issued: 2021
A multi-biometric feature-fusion framework for improved uni-modal and multi-modal human identification
- Brown, Dane L, Bradshaw, Karen L
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473696 , vital:77673 , xlink:href="https://ieeexplore.ieee.org/abstract/document/7568927"
- Description: The lack of multi-biometric fusion guidelines at the feature-level are addressed in this work. A feature-fusion framework is geared toward improving human identification accuracy for both single and multiple biometrics. The foundation of the framework is the improvement over a state-of-the-art uni-modal biometric verification system, which is extended into a multi-modal identification system. A novel multi-biometric system is thus designed based on the framework, which serves as fusion guidelines for multi-biometric applications that fuse at the feature-level. This framework was applied to the face and fingerprint to achieve a 91.11% recognition accuracy when using only a single training sample. Furthermore, an accuracy of 99.69% was achieved when using five training samples.
- Full Text:
- Date Issued: 2016
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473696 , vital:77673 , xlink:href="https://ieeexplore.ieee.org/abstract/document/7568927"
- Description: The lack of multi-biometric fusion guidelines at the feature-level are addressed in this work. A feature-fusion framework is geared toward improving human identification accuracy for both single and multiple biometrics. The foundation of the framework is the improvement over a state-of-the-art uni-modal biometric verification system, which is extended into a multi-modal identification system. A novel multi-biometric system is thus designed based on the framework, which serves as fusion guidelines for multi-biometric applications that fuse at the feature-level. This framework was applied to the face and fingerprint to achieve a 91.11% recognition accuracy when using only a single training sample. Furthermore, an accuracy of 99.69% was achieved when using five training samples.
- Full Text:
- Date Issued: 2016
A stability-indicating high performance liquid chromatographic assay for the determination of orlistat in capsules
- Mohammadi, Ali, Haririan, I, Rezanour, Nasrin, Ghiasi, L, Walker, Roderick B
- Authors: Mohammadi, Ali , Haririan, I , Rezanour, Nasrin , Ghiasi, L , Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184267 , vital:44195 , xlink:href="https://doi.org/10.1016/j.chroma.2006.03.038"
- Description: A stability-indicating HPLC method was developed and validated for the quantitative determination of orlistat in capsule dosage forms. An isocratic separation was achieved using a Perfectsil® target ODS-3, 250 mm × 4.6 mm i.d., 5 μm particle size column with a flow rate of 0.7 ml/min and using a UV detector to monitor the eluate at 210 nm. The mobile phase consisted of methanol:acetonitrile:trifluoroacetic acid (82.5:17.5:0.01, v/v/v). The drug was subjected oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compound and all degradation products in an overall analytical run time of approximately 15 min with the parent compound orlistat eluting at approximately 9 min. The method was linear over the concentration range of 0.02–0.75 mg/ml (r = 0.9998) with a limit of detection and quantitation 0.006 and 0.02 mg/ml, respectively. The method has the requisite accuracy, selectivity, sensitivity and precision to assay orlistat in capsules. Degradation products resulting from the stress studies did not interfere with the detection of orlistat and the assay is thus stability-indicating.
- Full Text:
- Date Issued: 2006
- Authors: Mohammadi, Ali , Haririan, I , Rezanour, Nasrin , Ghiasi, L , Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184267 , vital:44195 , xlink:href="https://doi.org/10.1016/j.chroma.2006.03.038"
- Description: A stability-indicating HPLC method was developed and validated for the quantitative determination of orlistat in capsule dosage forms. An isocratic separation was achieved using a Perfectsil® target ODS-3, 250 mm × 4.6 mm i.d., 5 μm particle size column with a flow rate of 0.7 ml/min and using a UV detector to monitor the eluate at 210 nm. The mobile phase consisted of methanol:acetonitrile:trifluoroacetic acid (82.5:17.5:0.01, v/v/v). The drug was subjected oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compound and all degradation products in an overall analytical run time of approximately 15 min with the parent compound orlistat eluting at approximately 9 min. The method was linear over the concentration range of 0.02–0.75 mg/ml (r = 0.9998) with a limit of detection and quantitation 0.006 and 0.02 mg/ml, respectively. The method has the requisite accuracy, selectivity, sensitivity and precision to assay orlistat in capsules. Degradation products resulting from the stress studies did not interfere with the detection of orlistat and the assay is thus stability-indicating.
- Full Text:
- Date Issued: 2006
Adaptive machine learning based network intrusion detection
- Chindove, Hatitye E, Brown, Dane L
- Authors: Chindove, Hatitye E , Brown, Dane L
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/464052 , vital:76471 , xlink:href="https://doi.org/10.1145/3487923.3487938"
- Description: Network intrusion detection system (NIDS) adoption is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks make it challenging to classify network traffic. Machine learning (ML) techniques in a NIDS can be affected by different scenarios, and thus the recency, size and applicability of datasets are vital factors to consider when selecting and tuning a machine learning classifier. The proposed approach evaluates relatively new datasets constructed such that they depict real-world scenarios. It includes analyses of dataset balancing and sampling, feature engineering and systematic ML-based NIDS model tuning focused on the adaptive improvement of intrusion detection. A comparison between machine learning classifiers forms part of the evaluation process. Results on the proposed approach model effectiveness for NIDS are discussed. Recurrent neural networks and random forests models consistently achieved high f1-score results with macro f1-scores of 0.73 and 0.87 for the CICIDS 2017 dataset; and 0.73 and 0.72 against the CICIDS 2018 dataset, respectively.
- Full Text:
- Date Issued: 2021
- Authors: Chindove, Hatitye E , Brown, Dane L
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/464052 , vital:76471 , xlink:href="https://doi.org/10.1145/3487923.3487938"
- Description: Network intrusion detection system (NIDS) adoption is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks make it challenging to classify network traffic. Machine learning (ML) techniques in a NIDS can be affected by different scenarios, and thus the recency, size and applicability of datasets are vital factors to consider when selecting and tuning a machine learning classifier. The proposed approach evaluates relatively new datasets constructed such that they depict real-world scenarios. It includes analyses of dataset balancing and sampling, feature engineering and systematic ML-based NIDS model tuning focused on the adaptive improvement of intrusion detection. A comparison between machine learning classifiers forms part of the evaluation process. Results on the proposed approach model effectiveness for NIDS are discussed. Recurrent neural networks and random forests models consistently achieved high f1-score results with macro f1-scores of 0.73 and 0.87 for the CICIDS 2017 dataset; and 0.73 and 0.72 against the CICIDS 2018 dataset, respectively.
- Full Text:
- Date Issued: 2021
An analysis on the re-emergence of SQL Slammer worm using network telescope data
- Chindipha, Stones D, Irwin, Barry V W
- Authors: Chindipha, Stones D , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473718 , vital:77675 , xlink:href="https://www.researchgate.net/publication/327622806_An_Analysis_on_the_Re-emergence_of_SQL_Slammer_Worm_Using_Network_Telescope_Data"
- Description: The SQL Slammer worm is a self propagated computer virus that caused a denial of service on some Internet hosts and dramatically slowed down general Internet traffic. An observation of network traffic captured in the Rhodes University’s network telescopes shows that traffic observed in it shows an escalation in the number of packets captured by the telescopes between January 2014 and December 2016 when the expected traffic was meant to take a constant decline in UDP packets from port 1434. Using data captured over a period of 84 months, the analysis done in this study identified top ten /24 source IP addresses that Slammer worm repeatedly used for this attack together with their geolocation. It also shows the trend of UDP 1434 packets received by the two network telescopes from January 2009 to December 2015. In line with epidemic model, the paper has shown how this traffic fits in as SQL Slammer worm attack. Consistent number of packets observed in the two telescopes between 2014 and 2016 shows qualities of the Slammer worm attack. Basic time series and decomposition of additive time series graphs have been used to show trend and observed UDP packets over the time frame of study.
- Full Text:
- Date Issued: 2017
- Authors: Chindipha, Stones D , Irwin, Barry V W
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473718 , vital:77675 , xlink:href="https://www.researchgate.net/publication/327622806_An_Analysis_on_the_Re-emergence_of_SQL_Slammer_Worm_Using_Network_Telescope_Data"
- Description: The SQL Slammer worm is a self propagated computer virus that caused a denial of service on some Internet hosts and dramatically slowed down general Internet traffic. An observation of network traffic captured in the Rhodes University’s network telescopes shows that traffic observed in it shows an escalation in the number of packets captured by the telescopes between January 2014 and December 2016 when the expected traffic was meant to take a constant decline in UDP packets from port 1434. Using data captured over a period of 84 months, the analysis done in this study identified top ten /24 source IP addresses that Slammer worm repeatedly used for this attack together with their geolocation. It also shows the trend of UDP 1434 packets received by the two network telescopes from January 2009 to December 2015. In line with epidemic model, the paper has shown how this traffic fits in as SQL Slammer worm attack. Consistent number of packets observed in the two telescopes between 2014 and 2016 shows qualities of the Slammer worm attack. Basic time series and decomposition of additive time series graphs have been used to show trend and observed UDP packets over the time frame of study.
- Full Text:
- Date Issued: 2017
An Automated System for Detecting and Preventing Phishing Attempts on Steam Accounts
- Sonne, Kabir, Chindipha, Stones D
- Authors: Sonne, Kabir , Chindipha, Stones D
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473729 , vital:77676 , xlink:href="https://ieeexplore.ieee.org/abstract/document/10389578"
- Description: In recent years Steam has become a giant in the gaming industry. The Valve-owned digital distribution platform held an estimated 75% of market share in 2013, and continues to grow. However, with such a large user base comes the ever-increasing threat of security breaches in both the Steam database and individual Steam user accounts. While Steam does make use of a mobile authentication app, users are still susceptible to malware and/or phishing attempts that can cause users to lose access to their accounts through manipulation or gaining access to recovery email accounts. This project aims to investigate how the authentication process can be improved or if a solution can be created to help prevent the worst-case scenario when users become victims of phishing attacks.
- Full Text:
- Date Issued: 2023
- Authors: Sonne, Kabir , Chindipha, Stones D
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473729 , vital:77676 , xlink:href="https://ieeexplore.ieee.org/abstract/document/10389578"
- Description: In recent years Steam has become a giant in the gaming industry. The Valve-owned digital distribution platform held an estimated 75% of market share in 2013, and continues to grow. However, with such a large user base comes the ever-increasing threat of security breaches in both the Steam database and individual Steam user accounts. While Steam does make use of a mobile authentication app, users are still susceptible to malware and/or phishing attempts that can cause users to lose access to their accounts through manipulation or gaining access to recovery email accounts. This project aims to investigate how the authentication process can be improved or if a solution can be created to help prevent the worst-case scenario when users become victims of phishing attacks.
- Full Text:
- Date Issued: 2023
An evaluation of hand-based algorithms for sign language recognition
- Marais, Marc, Brown, Dane L, Connan, James, Boby, Alden
- Authors: Marais, Marc , Brown, Dane L , Connan, James , Boby, Alden
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465124 , vital:76575 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9856310"
- Description: Sign language recognition is an evolving research field in computer vision, assisting communication between hearing disabled people. Hand gestures contain the majority of the information when signing. Focusing on feature extraction methods to obtain the information stored in hand data in sign language recognition may improve classification accuracy. Pose estimation is a popular method for extracting body and hand landmarks. We implement and compare different feature extraction and segmentation algorithms, focusing on the hands only on the LSA64 dataset. To extract hand landmark coordinates, MediaPipe Holistic is implemented on the sign images. Classification is performed using poplar CNN architectures, namely ResNet and a Pruned VGG network. A separate 1D-CNN is utilised to classify hand landmark coordinates extracted using MediaPipe. The best performance was achieved on the unprocessed raw images using a Pruned VGG network with an accuracy of 95.50%. However, the more computationally efficient model using the hand landmark data and 1D-CNN for classification achieved an accuracy of 94.91%.
- Full Text:
- Date Issued: 2022
- Authors: Marais, Marc , Brown, Dane L , Connan, James , Boby, Alden
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465124 , vital:76575 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9856310"
- Description: Sign language recognition is an evolving research field in computer vision, assisting communication between hearing disabled people. Hand gestures contain the majority of the information when signing. Focusing on feature extraction methods to obtain the information stored in hand data in sign language recognition may improve classification accuracy. Pose estimation is a popular method for extracting body and hand landmarks. We implement and compare different feature extraction and segmentation algorithms, focusing on the hands only on the LSA64 dataset. To extract hand landmark coordinates, MediaPipe Holistic is implemented on the sign images. Classification is performed using poplar CNN architectures, namely ResNet and a Pruned VGG network. A separate 1D-CNN is utilised to classify hand landmark coordinates extracted using MediaPipe. The best performance was achieved on the unprocessed raw images using a Pruned VGG network with an accuracy of 95.50%. However, the more computationally efficient model using the hand landmark data and 1D-CNN for classification achieved an accuracy of 94.91%.
- Full Text:
- Date Issued: 2022
An Evaluation of Text Mining Techniques in Sampling of Network Ports from IBR Traffic
- Chindipha, Stones D, Irwin, Barry V W, Herbert, Alan
- Authors: Chindipha, Stones D , Irwin, Barry V W , Herbert, Alan
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473740 , vital:77677 , xlink:href="https://www.researchgate.net/profile/Stones-Chindi-pha/publication/335910179_An_Evaluation_of_Text_Mining_Techniques_in_Sampling_of_Network_Ports_from_IBR_Traffic/links/5d833084458515cbd1985a38/An-Evaluation-of-Text-Mining-Techniques-in-Sampling-of-Network-Ports-from-IBR-Traffic.pdf"
- Description: Information retrieval (IR) has had techniques that have been used to gauge the extent to which certain keywords can be retrieved from a document. These techniques have been used to measure similarities in duplicated images, native language identification, optimize algorithms, among others. With this notion, this study proposes the use of four of the Information Retrieval Techniques (IRT/IR) to gauge the implications of sampling a/24 IPv4 ports into smaller subnet equivalents. Using IR, this paper shows how the ports found in a/24 IPv4 net-block relate to those found in the smaller subnet equivalents. Using Internet Background Radiation (IBR) data that was collected from Rhodes University, the study found compelling evidence of the viability of using such techniques in sampling datasets. Essentially, being able to identify the variation that comes with sampling the baseline dataset. It shows how the various samples are similar to the baseline dataset. The correlation observed in the scores proves how viable these techniques are to quantifying variations in the sampling of IBR data. In this way, one can identify which subnet equivalent best represents the unique ports found in the baseline dataset (IPv4 net-block dataset).
- Full Text:
- Date Issued: 2019
- Authors: Chindipha, Stones D , Irwin, Barry V W , Herbert, Alan
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473740 , vital:77677 , xlink:href="https://www.researchgate.net/profile/Stones-Chindi-pha/publication/335910179_An_Evaluation_of_Text_Mining_Techniques_in_Sampling_of_Network_Ports_from_IBR_Traffic/links/5d833084458515cbd1985a38/An-Evaluation-of-Text-Mining-Techniques-in-Sampling-of-Network-Ports-from-IBR-Traffic.pdf"
- Description: Information retrieval (IR) has had techniques that have been used to gauge the extent to which certain keywords can be retrieved from a document. These techniques have been used to measure similarities in duplicated images, native language identification, optimize algorithms, among others. With this notion, this study proposes the use of four of the Information Retrieval Techniques (IRT/IR) to gauge the implications of sampling a/24 IPv4 ports into smaller subnet equivalents. Using IR, this paper shows how the ports found in a/24 IPv4 net-block relate to those found in the smaller subnet equivalents. Using Internet Background Radiation (IBR) data that was collected from Rhodes University, the study found compelling evidence of the viability of using such techniques in sampling datasets. Essentially, being able to identify the variation that comes with sampling the baseline dataset. It shows how the various samples are similar to the baseline dataset. The correlation observed in the scores proves how viable these techniques are to quantifying variations in the sampling of IBR data. In this way, one can identify which subnet equivalent best represents the unique ports found in the baseline dataset (IPv4 net-block dataset).
- Full Text:
- Date Issued: 2019
Bushmeat use is widespread but under-researched in rural communities of South Africa
- Martins, Vusumzi, Shackleton, Charlie M
- Authors: Martins, Vusumzi , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179745 , vital:43167 , xlink:href="https://doi.org/10.1016/j.gecco.2019.e00583"
- Description: Bushmeat hunting and consumption is common throughout sub-Saharan Africa. Yet, a recent review indicated that the prevalence and nature of bushmeat hunting was little researched or understood in southern African savannas. Here we present information from a number of rural livelihoods studies in South Africa that indicate that bushmeat consumption is common, with typically between 30 and 60% of rural households in the communal tenure regions stating that they consume it. Yet there are only five studies in the country explicitly investigating bushmeat hunting practices, motivations, offtake and target species. A review of the five studies indicates that bushmeat hunting is largely a male activity and that motivations and practices vary between sites. Hunting with dogs is the most common method, targeting multiple small and medium-sized species. With such widespread consumption, it is possible that bushmeat hunting may have significant effects on the population status of some target species and consequently requires urgent and in-depth research of both practices and effects
- Full Text:
- Date Issued: 2019
- Authors: Martins, Vusumzi , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179745 , vital:43167 , xlink:href="https://doi.org/10.1016/j.gecco.2019.e00583"
- Description: Bushmeat hunting and consumption is common throughout sub-Saharan Africa. Yet, a recent review indicated that the prevalence and nature of bushmeat hunting was little researched or understood in southern African savannas. Here we present information from a number of rural livelihoods studies in South Africa that indicate that bushmeat consumption is common, with typically between 30 and 60% of rural households in the communal tenure regions stating that they consume it. Yet there are only five studies in the country explicitly investigating bushmeat hunting practices, motivations, offtake and target species. A review of the five studies indicates that bushmeat hunting is largely a male activity and that motivations and practices vary between sites. Hunting with dogs is the most common method, targeting multiple small and medium-sized species. With such widespread consumption, it is possible that bushmeat hunting may have significant effects on the population status of some target species and consequently requires urgent and in-depth research of both practices and effects
- Full Text:
- Date Issued: 2019
Catalytic behavior of osmium (II), rhodium (III) and ruthenium (II) Phthalocyanines towards the electrooxidation of cysteine on glassy carbon electrodes
- Sekota, Mantoa, Nyokong, Tebello
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
- Date Issued: 1997
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
- Date Issued: 1997
Characterization and computational studies of a co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl) amino] propanoic acid
- Odame, Felix, Hosten, Eric C, Betz, Richard, Lobb, Kevin A, Tshentu, Zenixole R
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447030 , vital:74578 , xlink:href="https://doi.org/10.1134/S0022476618050268"
- Description: A novel co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl)amino] propanoic acid is synthesized and characterized by spectroscopy, elemental analysis, GC-MS, and single crystal XRD. A computation of the structures involved in the formation of the co-crystal are carried out and their contribution to reactivity is explained.
- Full Text:
- Date Issued: 2018
- Authors: Odame, Felix , Hosten, Eric C , Betz, Richard , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447030 , vital:74578 , xlink:href="https://doi.org/10.1134/S0022476618050268"
- Description: A novel co-crystal of 2-aminobenzimidazole and 2-[(benzoylcarbamothioyl)amino] propanoic acid is synthesized and characterized by spectroscopy, elemental analysis, GC-MS, and single crystal XRD. A computation of the structures involved in the formation of the co-crystal are carried out and their contribution to reactivity is explained.
- Full Text:
- Date Issued: 2018
Chlorophyll fluorometry as a method of determining the effectiveness of a biological control agent in post-release evaluations
- Miller, Benjamin E, Coetzee, Julie A, Hill, Martin P
- Authors: Miller, Benjamin E , Coetzee, Julie A , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417438 , vital:71453 , xlink:href="https://doi.org/10.1080/09583157.2019.1656165"
- Description: The impact of the planthopper Megamelus scutellaris, a biocontrol agent of water hyacinth in South Africa, was assessed using chlorophyll fluorometry in a greenhouse study under two different eutrophic nutrient treatments and agent densities (high and low). The results indicated that plants grown in low nutrients with high densities of M. scutellaris showed the greatest reduction in the fluorescence parameters Fv/Fm and PIabs. The successful use of chlorophyll fluorometry for the detection of subtle insect damage to water hyacinth leaves could have future application in post-release studies to measure the impact of M. scutellaris in the field.
- Full Text:
- Date Issued: 2019
- Authors: Miller, Benjamin E , Coetzee, Julie A , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417438 , vital:71453 , xlink:href="https://doi.org/10.1080/09583157.2019.1656165"
- Description: The impact of the planthopper Megamelus scutellaris, a biocontrol agent of water hyacinth in South Africa, was assessed using chlorophyll fluorometry in a greenhouse study under two different eutrophic nutrient treatments and agent densities (high and low). The results indicated that plants grown in low nutrients with high densities of M. scutellaris showed the greatest reduction in the fluorescence parameters Fv/Fm and PIabs. The successful use of chlorophyll fluorometry for the detection of subtle insect damage to water hyacinth leaves could have future application in post-release studies to measure the impact of M. scutellaris in the field.
- Full Text:
- Date Issued: 2019
Chromone Studies. Part 17. Tricyclic Scaffolds from Reactions of chromone-3-carbaldehydes and methyl vinyl ketone under Baylis–Hillman conditions
- Ganto, Mlungiseleli M, Molefe, Duduzile M, Lobb, Kevin A, Kaye, Perry T
- Authors: Ganto, Mlungiseleli M , Molefe, Duduzile M , Lobb, Kevin A , Kaye, Perry T
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449321 , vital:74811 , xlink:href="https://doi.org/10.3184/030823409X4652"
- Description: Reaction of a series of chromone-3-carbaldehydes with methyl vinyl ketone under Baylis–Hillman conditions, using 3-hydroxyquinuclidine in chloroform or DABCO in 1-methyl-2-pyrrolidinone, affords unprecedented tricylic chromone derivatives which, depending on the conditions, may be accompanied by the normal Baylis–Hillman products or their respective tricyclic dimers.
- Full Text:
- Date Issued: 2009
- Authors: Ganto, Mlungiseleli M , Molefe, Duduzile M , Lobb, Kevin A , Kaye, Perry T
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449321 , vital:74811 , xlink:href="https://doi.org/10.3184/030823409X4652"
- Description: Reaction of a series of chromone-3-carbaldehydes with methyl vinyl ketone under Baylis–Hillman conditions, using 3-hydroxyquinuclidine in chloroform or DABCO in 1-methyl-2-pyrrolidinone, affords unprecedented tricylic chromone derivatives which, depending on the conditions, may be accompanied by the normal Baylis–Hillman products or their respective tricyclic dimers.
- Full Text:
- Date Issued: 2009
Construction and characterization of carbon paste ultra-microelectrodes
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
Count me in: Leopard population density in an area of mixed land‐use, Eastern Cape, South Africa
- Bouderka, Safia, Perry, Travis W, Parker, Daniel M, Beukes, Maya, Mgqatsa, Nokubonga
- Authors: Bouderka, Safia , Perry, Travis W , Parker, Daniel M , Beukes, Maya , Mgqatsa, Nokubonga
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462591 , vital:76317 , xlink:href="https://doi.org/10.1111/aje.13078"
- Description: Although the leopard (Panthera pardus) has the widest range of any felid in the world is designated as a vulnerable species, mainly because of human-induced conflict (Jacobson et al., 2016). Our study focuses on a population of leopards on privately owned, mixed-use farmland (Baviaanskloof Hartland–BH hereafter) which is adjacent to the Baviaanskloof Mega Reserve (BMR) in the Baviaanskloof UNESCO World Heritage Site of the Eastern Cape, South Africa. Given the unique make-up of the region, with sometimes conflicting management objectives, the status of leopards in the broader Baviaanskloof is of particular interest to a range of stakeholders. However, despite the need for management decisions to be based on reliable and regular population monitoring efforts (Elliot et al., 2020), the last formal assessment of the leopard population in the Baviaanskloof was performed in 2011/2012 but published 9 years later (Devens et al., 2018). The only other assessment of the status of leopards in the region was an unpublished Master's project (McManus, 2009). Here, we use photographic captures of leopards and a Spatially Explicit Capture Recapture (SECR) analytical framework in the mixed-use BH region of the Baviaanskloof to generate an up-to-date leopard population density estimate that can inform conservation management of the species in this important World Heritage Site.
- Full Text:
- Date Issued: 2023
- Authors: Bouderka, Safia , Perry, Travis W , Parker, Daniel M , Beukes, Maya , Mgqatsa, Nokubonga
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/462591 , vital:76317 , xlink:href="https://doi.org/10.1111/aje.13078"
- Description: Although the leopard (Panthera pardus) has the widest range of any felid in the world is designated as a vulnerable species, mainly because of human-induced conflict (Jacobson et al., 2016). Our study focuses on a population of leopards on privately owned, mixed-use farmland (Baviaanskloof Hartland–BH hereafter) which is adjacent to the Baviaanskloof Mega Reserve (BMR) in the Baviaanskloof UNESCO World Heritage Site of the Eastern Cape, South Africa. Given the unique make-up of the region, with sometimes conflicting management objectives, the status of leopards in the broader Baviaanskloof is of particular interest to a range of stakeholders. However, despite the need for management decisions to be based on reliable and regular population monitoring efforts (Elliot et al., 2020), the last formal assessment of the leopard population in the Baviaanskloof was performed in 2011/2012 but published 9 years later (Devens et al., 2018). The only other assessment of the status of leopards in the region was an unpublished Master's project (McManus, 2009). Here, we use photographic captures of leopards and a Spatially Explicit Capture Recapture (SECR) analytical framework in the mixed-use BH region of the Baviaanskloof to generate an up-to-date leopard population density estimate that can inform conservation management of the species in this important World Heritage Site.
- Full Text:
- Date Issued: 2023
Cryptojacking Detection in Cloud Infrastructure Using Network Traffic
- Kwedza, Philip, Chindipha, Stones D
- Authors: Kwedza, Philip , Chindipha, Stones D
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473762 , vital:77679 , xlink:href="https://ieeexplore.ieee.org/abstract/document/10389593"
- Description: Cryptomining is a way to obtain cryptocurrency, by performing computationally complex puzzles in exchange for a reward. To perform this requires expensive specialised hardware to become profitable but most times, this is not viable. Cryptojacking is a cybercrime in which an attacker uses devices to mine cryptocurrency without permission. This attack can be extended to use the resources of networks and cloud infrastructure. This research aimed to develop a model that could detect cryptojacking automatically in a cloud environment, utilising network traffic. The models in this paper solved this by developing a machine learning model that could analyse cryptojacking in a dataset of network traffic from an attacked cloud server.
- Full Text:
- Date Issued: 2023
- Authors: Kwedza, Philip , Chindipha, Stones D
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473762 , vital:77679 , xlink:href="https://ieeexplore.ieee.org/abstract/document/10389593"
- Description: Cryptomining is a way to obtain cryptocurrency, by performing computationally complex puzzles in exchange for a reward. To perform this requires expensive specialised hardware to become profitable but most times, this is not viable. Cryptojacking is a cybercrime in which an attacker uses devices to mine cryptocurrency without permission. This attack can be extended to use the resources of networks and cloud infrastructure. This research aimed to develop a model that could detect cryptojacking automatically in a cloud environment, utilising network traffic. The models in this paper solved this by developing a machine learning model that could analyse cryptojacking in a dataset of network traffic from an attacked cloud server.
- Full Text:
- Date Issued: 2023
Dual-Catalyst Acceleration of Tandem Disulfide Cleavage and Baylis–Hillman Synthesis of 2 H-1-Benzothiopyran Derivatives
- Nyoni, Dubekile, Lobb, Kevin A, Kaye, Perry T
- Authors: Nyoni, Dubekile , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448898 , vital:74769 , xlink:href="https://doi.org/10.1080/00397911.2012.673449"
- Description: While both 1,8-diazabicyclo[5.4.0]undec-7-ene and triphenylphosphine catalyze tandem Baylis–Hillman reaction/disulfide cleavage of 2,2′-dithiodibenzaldehyde independently, when used together as a dual-catalyst system, the overall yields of the cyclized 2H-1-benzothiopyrans are consistently greater and the reaction time decreases dramatically.
- Full Text:
- Date Issued: 2013
- Authors: Nyoni, Dubekile , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448898 , vital:74769 , xlink:href="https://doi.org/10.1080/00397911.2012.673449"
- Description: While both 1,8-diazabicyclo[5.4.0]undec-7-ene and triphenylphosphine catalyze tandem Baylis–Hillman reaction/disulfide cleavage of 2,2′-dithiodibenzaldehyde independently, when used together as a dual-catalyst system, the overall yields of the cyclized 2H-1-benzothiopyrans are consistently greater and the reaction time decreases dramatically.
- Full Text:
- Date Issued: 2013
Early dehydration detection using infrared imaging
- Poole, Louise C, Brown, Dane L, Connan, James
- Authors: Poole, Louise C , Brown, Dane L , Connan, James
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465656 , vital:76629 , xlink:href="https://www.researchgate.net/profile/Louise-Poole-3/publication/357578445_Early_Dehydration_Detection_Using_Infrared_Imaging/links/61d5664eb8305f7c4b231d50/Early-Dehydration-Detection-Using-Infrared-Imaging.pdf"
- Description: Crop loss and failure have devastating impacts on a country’s economy and food security. Developing effective and inexpensive systems to minimize crop loss has become essential. Recently, multispectral imaging—in particular visible and infrared imaging—have become popular for analyzing plants and show potential for early identification of plant stress. We created a directly comparable visible and infrared image dataset for dehydration in spinach leaves. We created and compared various models trained on both datasets and concluded that the models trained on the infrared dataset outperformed all of those trained on the visible dataset. In particular, the models trained to identify early signs of dehydration yielded 45% difference in accuracy, with the infrared model obtaining 70% accuracy and the visible model obtaining 25% accuracy. Infrared imaging thus shows promising potential for application in early plant stress and disease identification.
- Full Text:
- Date Issued: 2021
- Authors: Poole, Louise C , Brown, Dane L , Connan, James
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465656 , vital:76629 , xlink:href="https://www.researchgate.net/profile/Louise-Poole-3/publication/357578445_Early_Dehydration_Detection_Using_Infrared_Imaging/links/61d5664eb8305f7c4b231d50/Early-Dehydration-Detection-Using-Infrared-Imaging.pdf"
- Description: Crop loss and failure have devastating impacts on a country’s economy and food security. Developing effective and inexpensive systems to minimize crop loss has become essential. Recently, multispectral imaging—in particular visible and infrared imaging—have become popular for analyzing plants and show potential for early identification of plant stress. We created a directly comparable visible and infrared image dataset for dehydration in spinach leaves. We created and compared various models trained on both datasets and concluded that the models trained on the infrared dataset outperformed all of those trained on the visible dataset. In particular, the models trained to identify early signs of dehydration yielded 45% difference in accuracy, with the infrared model obtaining 70% accuracy and the visible model obtaining 25% accuracy. Infrared imaging thus shows promising potential for application in early plant stress and disease identification.
- Full Text:
- Date Issued: 2021