A computer aided machining system for the manufacture of three-dimensional surfaces

Includes bibliographical references.This thesis describes the design of a computerised system for machining three-dimensional surfaces, more specifically "sculptured surfaces", using an IBM PC and a Bridgeport 3 axis Computer Numerically Controlled (CNC) Milling Machine. There was a twofold objective to the project: To design and develop a milling system; To provide a teaching tool for undergraduate students who wish to further their studies in the concepts of Computer Aided Design and Manufacture (CAD/CAM). Five broad areas are covered: 1. The development of a mathematical algorithm to approximate a sculptured surf ace represented by a set, of surface datapoints in the form of XYZ coordinates. 2. The development of an algorithm to calculate the toolpath to machine the sculptured surface. 3. The development of an algorithm to display the surface and toolpath in three dimensions on the computer screen. 4. The development of an algorithm (the postprocessor) which translates the toolpath into a program suitable for use with the CNC milling machine. 5. The development of a communications algorithm for the direct transmission of the CNC program from the IBM microcomputer to the memory of the CNC computer

Diterpene modulator of macrophage phagosomal maturation

Novel uses for diterpene modulators of macrophage phagosomal maturation are provided. The diterpene isotuberculosinol is used as an immune modulator, assay for pharmaceutical compositions and an isolated Mycobacterium tuberculosis labdane-related diterpenoid virulence factor. A method of treating Mycobacterium tuberculosis infectivity is further provided

Selling space and time : the case of sejjieh dekorattiv

Sometime during the late 1980's, the weathered stones from dismantled or collapsed dry-stone walls started being gathered, and their outer surfaces were sawn away in laminae about an inch thick. Such laminae, weathered and rugged on one side, freshly cut and smooth on the other, were then glued side by side to the facades of newly-built houses. The neatly cut, white limestone ashlar masonry in which these facades, like most buildings in Malta, had been raised, was concealed beneath the collage of darkened and irregularly shaped slices of rubble. At first glance, the areas treated in this way had been transformed into a rubble wall. Ethnographic research has been conducted in San Gwann, a suburban village and Rabat, a small town. Several streets were explored in these localities in order to obtain some understanding of the distribution of sejjieh dekorattiv throughout the village or town, paying close attention to the role it plays in the context of particular facades. Fifteen informal interviews were carried out with a number of home-owners, aimed at eliciting their perceptions of sejjieh dekorattiv. This article is the first result of an ongoing research project. Important issues, such as the trends which emerge from the overall distribution of sejjieh dekorattiv throughout Malta as a whole have not as yet been tackled. The observations which follow must not be seen as definitive. They should rather be seen as an attempt to initiate discussion and investigation of this issue.peer-reviewe

The transition from a coherent optical vortex to a Rankine vortex: beam contrast dependence on topological charge

Spatially coherent helically phased light beams carry orbital angular momentum (OAM) and contain phase singularities at their centre. Destructive interference at the position of the phase singularity means the intensity at this point is necessarily zero, which results in a high contrast between the centre and the surrounding annular intensity distribution. Beams of reduced spatial coherence yet still carrying OAM have previously been referred to as Rankine vortices. Such beams no longer possess zero intensity at their centre, exhibiting a contrast that decreases as their spatial coherence is reduced. In this work, we study the contrast of a vortex beam as a function of its spatial coherence and topological charge. We show that beams carrying higher values of topological charge display a radial intensity contrast that is more resilient to a reduction in spatial coherence of the source

Biochemical characterization of the castor bean ent-kaurene synthase(-like) family supports quantum chemical view of diterpene cyclization

It has become apparent that plants have extensively diversified their arsenal of labdane-related diterpenoids (LRDs), in part via gene duplication and neo-functionalization of the ancestral entkaurene synthase (KS) required for gibberellin metabolism. For example, castor bean (Ricinus communis) was previously shown to produce an interesting set of biosynthetically related diterpenes, specifically ent-sandracopimaradiene, ent-beyerene, and ent-trachylobane, in addition to ent-kaurene, using four separate diterpene synthases, albeit these remain unidentified. Notably, despite mechanistic similarity of the underlying reaction to that catalyzed by KSs, ent-beyerene and ent-trachylobane synthases have not yet been identified. Given our interest in LRD biosynthesis, and the recent availability of the castor bean genome sequence, we applied a synthetic biology approach to biochemically characterize the four KS(-like) enzymes [KS(L)s] found in Ricinus communis [i.e., the RcKS(L)s]. In particular, using bacteria engineered to produce the relevant ent-copalyl diphosphate precursor and synthetic genes based on the predicted RcKS(L)s, although this ultimately required correction of a “splicing” error in one of the predicted genes, highlighting the dependence of such a synthetic biology approach on accurate gene sequences. Nevertheless, we can assign each of the four RcKS(L)s to one of the previously observed diterpene synthase activities, providing access to functionally novel enzymes. Intriguingly, the product distribution of the RcKS(L)s seems to support the distinct diterpene synthase reaction mechanism proposed by quantum chemical calculations, rather than the classically proposed pathway

Effect of Isotopically Sensitive Branching on Product Distribution for Pentalenene Synthase: Support for a Mechanism Predicted by Quantum Chemistry

Mechanistic proposals for the carbocation cascade reaction leading to the tricyclic sesquiterpene pentalenene are assessed in light of the results of isotopically sensitive branching experiments with the H309A mutant of pentalenene synthase. These experimental results support a mechanism for pentalenene formation involving a 7-protoilludyl cation whose intermediacy was first predicted using quantum-chemical calculations

Phenoxodiol protects against Cisplatin induced neurite toxicity in a PC-12 cell model

BACKGROUND: Many commonly used chemotherapeutic agents, such as Cisplatin, are restricted in their potential anti-neoplastic effectiveness by their side effects, with one of the most problematic being induction of peripheral neuropathy. Although a number of different neurotrophic, neuroprotective or anti-oxidant treatments have been tried in order to prevent or treat the neuropathies, to date they have met with limited success. Phenoxodiol is a new chemotherapeutic agent that has anti-proliferative and apoptotic effects on a range of cancer cells. PC12 cells are a commonly used neuronal cell model for examination of neurite outgrowth. In this study we examined whether phenoxodiol could protect against Cisplatin induced neurite inhibition in PC12 cells as an indication of the potential to protect against neuropathy. RESULTS: Using the PC12 neuronal cell line, concentrations of Cisplatin were chosen that induced moderate or strong neurite toxicity within 24 hrs but were not cytotoxic. The effect of Phenoxodiol on Cisplatin induced neurite toxicity was assessed by measurement of neurite outgrowth. Addition of phenoxodiol at 100 nM or 1 microM showed no cytotoxicity and blocked the Cisplatin induced neurite toxicity, while phenoxodiol at 10 microM was cytotoxic and enhanced neurite toxicity of Cisplatin. When Cisplatin was added for 24 hrs, then washed out and the cells allowed to recover for 48 hrs, neurite outgrowth was not restored and addition of phenoxodiol did not further promote recovery or restore the Cisplatin treated cells. CONCLUSION: In addition to its potential as a chemotherapeutic agent Phenoxodiol may thus also have the potential to be used in conjunction with Cisplatin chemotherapy to prevent induction of neuropathy