The use of ferrocene and camphor for the synthesis of carbon nanotubes using catalystic chemical vapor deposition

The discovery of carbon nanotubes (CNTs) has sparked great interest in the scientific world because of their remarkable electrical and physical properties. Only a thorough understanding of these properties, however, will allow CNTs to be commercially viable. Essentially, CNTs are graphite-like surfaces of sp2 hybridized carbon atoms in the form of tubes. CNTs could range from single-walled carbon nanotubes (SWNTs), consisting of one cylindrical graphite sheet to multi-walled nanotubes (MWNTs) that have concentric sheets. Nanotubes can be synthesized using a number of techniques such as electric arc–discharge, laser ablation and catalytic chemical vapor deposition (CCVD). In this project the CCVD technique was used for the synthesis of CNTs because of it simplicity and availability. The source of carbon was not the conventional hydrocarbon gas, but was camphor, a botanical hydrocarbon that is a solid at room–temperature. Ferrocene was the catalyst, not only because it has been used before in the synthesis of nanotubes, but it appears to be one of the best catalysts during the CCVD synthesis of nanotubes. The presence of nitrogen gas is known to assist in the synthesis of CNTs that have a bamboo–like structure; hence the effect of carrier gases such as nitrogen, argon/hydrogen and argon on the quality of nanotubes synthesized was investigated. Initially, the optimal experimental method for the synthesis of CNTs was determined by varying the reaction path length, temperature, mixing the catalyst and carbon source together or keeping them separate and varying the %m/m of the catalyst to carbon source. It was found that either an increase in the reaction temperature or an increased path length resulted in an increase in the mass of product obtained, whereas mixing the catalyst and carbon source together as opposed to them being separated only caused a slight variation in the mass of product synthesized. The mass of product synthesized also increased as the catalyst concentration increased. The remainder of the project was aimed at investigating the role of different gases: nitrogen, argon and hydrogen (in argon) in the CCVD synthesis of CNTs. The resulting materials were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and laser Raman analysis. The results indicated that this method could be tailored to synthesize either carbon spheres or carbon nanotubes of specific diameters and quality. Finally, in an attempt to synthesize aligned carbon nanotubes, catalyst supports {characterized using Brunauer-Emmett-Teller analysis (BET)} namely; silica, alumina and magnesium oxide were used. Although this was not successful for the synthesis of aligned CNTs under the conditions used, alumina showed the most promise.Mr. S. Durbach Dr. R. W. Kraus

In Search Of An Alternative Route To Germasilenes: The Synthesis And Chemistry Of (halosilyl)germanes

This thesis describes attempts to prepare a germasilene, a compound containing a germanium-silicon double bond, by either a {dollar}\beta{dollar}-elimination reaction or a reductive elimination reaction.;The precursor, Mes{dollar}\sb2{dollar}HGeSiClMes{dollar}\sb2{dollar}, 1, (Mes = 2,4,6-trimethylphenyl) was prepared by the addition of Mes{dollar}\sb2{dollar}HGeLi to Mes{dollar}\sb2{dollar}SiCl{dollar}\sb2{dollar} in THF in excellent yield. We examined the effect of changing the nature of the solvent, leaving group, base and ligands on the reaction between 1 and base.;Mes{dollar}\sb2{dollar}ClGeSiClMes{dollar}\sb2,{dollar} 29, and Mes{dollar}\sb2{dollar}BrGeSiClMes{dollar}\sb2{dollar}, 30, prepared by the chlorination and bromination of 1 respectively, were treated with lithium naphthalenide (LiNp) in an attempt to prepare Mes{dollar}\sb2{dollar}Ge = SiMes{dollar}\sb2{dollar} by a reductive elimination reaction. Although a stable germasilene was not isolated from the reaction between 29 or 30 and LiNp, the intermediate formation of a germasilene cannot be ruled out

Science Diplomacy, Epistemic Communities, and Practice in Sub-Saharan Africa

For many states in Sub-Saharan Africa, the capacity to participate in the international food standard setting process continues to be a challenge. The scientific and technical capacity for many states in this region remains low. This has consequences for African states beyond international food standard setting but for trade and economic development as well. The present paper considers how science diplomacy is mobilised to improve African scientific capacity and participation in international standard setting and thus the multilateral trading system. Through the conceptual frame of epistemic communities, we argue that science diplomacy is exemplified through how scientific expertise embedded within a set of international institutions seeks to build capacity and participation of African states in this important, yet often little considered aspect of international governance

Continual Learning of Object Instances

We propose continual instance learning - a method that applies the concept of continual learning to the task of distinguishing instances of the same object category. We specifically focus on the car object, and incrementally learn to distinguish car instances from each other with metric learning. We begin our paper by evaluating current techniques. Establishing that catastrophic forgetting is evident in existing methods, we then propose two remedies. Firstly, we regularise metric learning via Normalised Cross-Entropy. Secondly, we augment existing models with synthetic data transfer. Our extensive experiments on three large-scale datasets, using two different architectures for five different continual learning methods, reveal that Normalised cross-entropy and synthetic transfer leads to less forgetting in existing techniques.Comment: Accepted to CVPR 2020: Workshop on Continual Learning in Computer Visio

Quality of work life and career change among online technical advisors

There is currently a phenomenon of young people changing jobs in our country. This research looks at the reasons why mechanics leave the workshop environment to pursue a career as a technical advisor in the call centre. The technical advisors all make the transition at a particular stage in their lives and this will be looked at in terms of Super’s (1980) developmental theory, with a particular focus on the stage of establishment. The dissertation takes the reader on a journey through the lives of five technical advisors at a particular organisation, and compares and contrasts the two work environments and the quality of work life associated with both. The study will also focus on stress that they experience while making the transition from mechanic to technical advisor and how this impacts on their work and personal lives. The study was exploratory in nature and was investigated through the qualitative method of interviewing

LERNZdb Freshwater Database – fact sheet

The LERNZdb Freshwater Database is a repository for freshwater quality data and biodiversity measurement data for lakes, rivers and wetlands in New Zealand. It was developed as part of the Lake Ecosystem Restoration New Zealand (LERNZ: LERNZ.co.nz) programme in co-operation between the Information & Technology Services Division (ITS) and LERNZ researchers at the University of Waikato. LERNZdb has the ability to store a wide variety of freshwater data in a consistent format, it also scores the quality of the data based on the provided quality controlled information. This allows the user to filter data based on the standard of data collection and encourages the provision of high quality data for use in modelling applications

Dynamic modelling of the processing of peptides for presentation on major histocompatibility complex class I proteins

Antigen presentation is broadly implicated in disease and represents an important target for prophylactic and therapeutic treatments. A better understanding of the components of this system is fundamental to our understanding of disease path- ways and to treatment design. This thesis focuses on modelling the processing of peptides by enzymes in the cytosol and in the endoplasmic reticulum (ER) in the context of major histocompatibility complex class I (MHC) antigen presentation, and expounds upon current knowledge of the mechanistic details and specificity of both the proteasome and the endoplasmic reticulum aminopeptidase-1 (ERAP1). We use nonlinear ordinary differential equations to model the biochemical reaction pathways of amino-terminal peptide trimming by ERAP1 and distinguish parameter dependencies of two prevailing theories for the mechanism of ERAP1 trimming us- ing algebraic and numerical analysis. Importantly, we show that ERAP1 has a role in peptide optimisation when MHC acts as a template, but not when it trims free peptide using an internal molecular ruler. We present testable hypotheses that may elucidate the dominant trimming mechanism used by ERAP1 in vivo, which has been the subject of debate for more than 25 years. We show that all ERAP1 trimming mechanism hypotheses are able to predict the qualitative distribution of cell surface presentation of SIINFEKL derived from amino-terminally extended precursors. Notably, we find that the molecular ruler trimming mechanism is more robust than the MHC-as-template mechanism. Finally, we use neural networks to predict carboxyl-terminal cleavage by the proteasome, and demonstrate that we are able to distinguish between cleavage and non-cleavage sites on an unseen set of known peptide epitopes. Overall, this thesis contributes a more thorough quantitative and mechanistic understanding of the generation of peptides presented on MHC class I molecules