Energy audit methodology for belt conveyors

The electricity cost is one of the largest components of operating costs on a belt conveyor system. This dissertation introduces a unique Conveyor Electricity Cost Efficiency Audit Methodology (CECEAM). In the CECEAM the conveyor system is evaluated from a high to detail level in order to identify opportunities to improve electricity costs. The CECEAM includes methodologies and tools developed to analyze not only the conveyor belt alone, but also the materials handling system as a whole. The outline of the dissertation is structured as follows: Chapter 1 includes the background and problem identification by means of a literature study. The main objective, as well as specific objectives, is defined in this chapter. In chapter 2, the CECEAM is introduced and an overview of the total methodology is discussed. The data acquisition part of the CECEAM; documentation, personnel, walk, technical audit as well as the conveyor database is discussed in chapter 3. Chapter 4 concentrates on the Conveyor Energy Conversion Model (CECM) and the verification thereof. The Integrated Conveyor Energy Model (ICEM) methodology is introduced (in chapter 5) and the economic evaluation concepts and energy management basics needed in the CECEAM are covered. Chapter 6 covers a CECEAM case study where the practical application of the CECEAM is illustrated with ICEM simulations, opportunity identification and recommendations. The conclusion and recommendations for further studies is proposed in chapter 7.Dissertation (MSc (Electrical Engineering))--University of Pretoria, 2007.Electrical, Electronic and Computer Engineeringunrestricte

The Cytotoxic, Antimicrobial and Anticancer Properties of the Antimicrobial Peptide Nisin Z Alone and in Combination with Conventional Treatments

Nisin is an antimicrobial peptide commonly used as a food preservative since 1969. This peptide has potent antimicrobial activity against several Gram-positive bacterial strains, including clinically important and resistant pathogens. The combination of nisin with conventional antibiotics has been shown to improve the antimicrobial activity of these antibiotic agents. Apart from the antimicrobial properties of nisin, this AMP also displays promising anticancer potential towards several types of malignancies. The nisin Z variant is able to induce selective cytotoxicity in melanoma cells compared to non-malignant cells. It was shown that nisin Z disrupts the cell membrane integrity of melanoma cells and that cytotoxicity is likely due to the activation of an apoptotic pathway. In addition, when used in combination with the conventional chemotherapeutic agents, nisin Z has the potential to enhance the cytotoxicity of these chemotherapeutic agents against cultured melanoma cells. Nisin Z has great potential for clinical application considering its low cytotoxicity to non-malignant cells and its effectiveness against Gram-positive bacterial strains and certain cancers

Development and testing of a transcatheter heart valve with reduced calcification potential

IntroductionPatients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model.MethodsThe two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar—fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification.ResultsHeart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function.ConclusionIn the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients

The Potential Use of Natural and Structural Analogues of Antimicrobial Peptides in the Fight against Neglected Tropical Diseases

Recently, research into the development of new antimicrobial agents has been driven by the increase in resistance to traditional antibiotics and Emerging Infectious Diseases. Antimicrobial peptides (AMPs) are promising candidates as alternatives to current antibiotics in the treatment and prevention of microbial infections. AMPs are produced by all known living species, displaying direct antimicrobial killing activity and playing an important role in innate immunity. To date, more than 2000 AMPs have been discovered and many of these exhibit broad-spectrum antibacterial, antiviral and anti-parasitic activity. Neglected tropical diseases (NTDs) are caused by a variety of pathogens and are particularly wide-spread in low-income and developing regions of the world. Alternative, cost effective treatments are desperately needed to effectively battle these medically diverse diseases. AMPs have been shown to be effective against a variety of NTDs, including African trypanosomes, leishmaniosis and Chagas disease, trachoma and leprosy. In this review, the potential of selected AMPs to successfully treat a variety of NTD infections will be critically evaluated

A study of the early DNA methylation events in oxidative stressed cultured mammalian cells

Thesis (MSc (Biochemistry))--North-West University, Potchefstroom Campus, 2013Cells are continuously exposed to reactive oxygen species (ROS) causing oxidative stress. Cells can withstand and counteract ROS using defence mechanisms which range from free radical scavengers, antioxidant enzymes and DNA repair systems. Prolonged exposure of cells to oxidant species leads to the accumulation of genetic as well as epigenetic alterations. Exposure of cells to the non-radical hydrogen peroxide (H2O2) leads to the generation of hydroxyl radicals (˙OH) by Fenton reactions when H2O2 reacts with a metal iron in the vicinity of DNA. These OH are very reactive and attack DNA giving rise to lesions such as single stand breaks and base modifications, which could influence DNA methylation. DNA methylation is the post synthetic addition of methyl groups to the carbon 5 position of cytosine when cytosines are in the CpG dinucleotide context and is involved in gene expression. DNA methylation is considered to be very stable. Aberrant DNA methylation influences cancer related gene expression and genomic stability. The aim of this study was to investigate early changes in the global DNA -and gene specific methylation patterns of cultured mammalian cells when cells were exposed to H2O2. The term early refers to how soon following exposure to H2O2 over a six hour period changes in the DNA methylation pattern can be observed when exposing cells to H2O2 concentrations that causes oxidative DNA damage. Changes in the hOGG1 promoter methylation status and gene expression were evaluated as this gene plays a crucial role in the initiation of the base excision repair pathway for the repair of oxidative DNA damage caused by H2O2 exposure. Results obtained with the alkaline comet assay showed that H2O2 exposure led to oxidative DNA damage and decreased DNA repair capacity when cells were exposed to H2O2 in fully supplemented medium (DMEM + 10% FBS). A change in the global DNA methylation pattern was evaluated with the cytosine extension assay and an enzyme based methylation sensitive PCR was used to evaluate the change in the promoter methylation status of hOGG1. Changes in the global DNA- and gene (promoter) specific methylation patterns could be observed where; a degree of global DNA hypomethylation and hypermethylation of the hOGG1 promoter could be observed within the six hour period of exposure to a concentration of H2O2 that was also associated with a high level of oxidative DNA damage. Finally, a decrease in the expression of the hOGG1 gene was also observed following exposure to this concentration of H2O2 within the six hour exposure period. These findings suggests that oxidative DNA damage influences DNA methylation (both globally and gene specific) and that the expression of the hOGG1 gene is possibly influenced by promoter hypermethylation which is associated with oxidative DNA damage. Results were generated in human osteosarcoma (143B) cells. This cell line was used in order to investigate the effect of oxidative stress on the global DNA methylation pattern as well as the promoter methylation- and expression of the hOGG1 gene in wild type 143B cells (uncompromised complex III). Previous studies reported that in 143B cells in which complex III of the respiratory chain was compromised, by a knockdown system, deviations in the global DNA methylation pattern as well as the promoter methylation and expression of genes involved in DNA repair pathways could be observed.Master

Minerals, antinutrients content and the bioaccessibility of iron and zinc in cooked, spontaneously fermented-dried, and blanched-dried dark green leafy vegetables commonly consumed in Sub-Saharan Africa

Iron and zinc deficiencies remain a significant problem in sub-Saharan Africa. This study aimed at determining mineral, antinutrient contents of differently processed ALVs, and the bioaccessibility of iron and zinc from cooked, blanched-dried, as well as spontaneously fermented-dried ALVs. Mineral and antinutrient contents of ALVs were analysed and the bioaccessibility of iron and zinc from ALVs were analysed by in vitro dialysability assay. Iron, zinc, magnesium, and calcium contents of the ALVs were high. Compared to cooked vegetables, both spontaneously fermented-dried and blanched-dried vegetables had significantly lower levels of condensed tannins, while significantly lower total phenolic contents were found in blanched-dried vegetables. Compared to cooked counterparts, percentage iron and zinc bioaccessibilities in spontaneously fermented-dried and blanched-dried ALVs showed no significant (p > 0.05) differences except for iron in Ethiopian kale and zinc in amaranth. Based on data from this study, it is recommended that ALVS should be consumed concurrently with iron and zinc enhancers to enhance bioaccessibility.ISSN:1475-332