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Pretoria, South Africa

Smith A.,Ditsong National Museum of Cultural History | Botha H.,South African Institute for Objects Conservation | De Beer F.C.,Radiation Science | Ferg E.,Nelson Mandela Metropolitan University
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

The production techniques, corrosive deterioration, conservation and questions regarding authenticity of a small Egyptian bronze statuette of the Child Horus (in the collection of the Ditsong: National Museum of Cultural History in Pretoria) was scientifically examined and analysed. The statuette dates to Egypts 12th Dynasty. When the statuette was damaged, it was considered the appropriate time to obtain valuable information about its history and background through scientific research. Neutron tomography (NT), a relatively new non-destructive technique (NDT) to the South African R&D community to study museum objects, was applied to perform this research. The results from NT were supported by additional tests done through XRF and XRD analyses of samples taken from the damaged statuette. Results revealed that the lost-wax method was used in the manufacturing process. The extent of the restoration and materials used can be verified and as a result the deterioration of the object can now be monitored. This paper describes in detail the analytical techniques used in the study and how it contributed to the conservation of the statuette and its authenticity. © 2011 Elsevier B.V. All rights reserved.

Birgander R.,Radiation Science | Eklund A.,Umea University
Acta Neurologica Scandinavica | Year: 2011

Objective - Cerebrospinal fluid (CSF) dynamics and long-term shunt survival of the Strata® CSF shunt were evaluated in patients with idiopathic normal pressure hydrocephalus (INPH). Subjects and methods - Seventy-two patients with INPH received a Strata® valve. A CSF infusion test, neuroimaging and video recording of gait were performed at baseline and at 6 months (n=68) after surgery. Long-term shunt survivals were obtained from patient records. Results - The shunt survival at 1year was 94% and at 3years 92.5%. Forty-nine patients (72%) had an improved gait. Two patients were improved despite non-functioning shunts, indicating a possible placebo response. Nineteen patients were not improved at the 6-month follow-up. The shunt tests revealed a functioning shunt in 12; thus, unnecessary shunt revisions could be avoided. Seventeen patients showed a siphoning effect. Shunt revisions were made in six patients. Eight hygromas/subdural hematomas were found. Conclusions - The long-term survival of the Strata® valves was good, and a concern of complications is not a reason to exclude elderly with INPH from shunt surgery. Studies are needed to evaluate pros and cons of the anti-siphon device. Using a CSF shunt test, unnecessary shunt revisions may be avoided. © 2010 John Wiley & Sons A/S.

Viljoen J.,North West University South Africa | Campbell Q.P.,North West University South Africa | Le Roux M.,North West University South Africa | De Beer F.,Radiation Science
International Journal of Coal Preparation and Utilization | Year: 2015

The degradation of coal and the production of coal fines during handling and transport is a serious problem in processes that depend on closely sized large particles. To minimize the production of fines, a fundamental understanding of coal breakage is required, so, to clarify the complex nature of coal breakage, a series of experiments was conducted to determine the influence of the internal physical coal structures on compression breakage characteristics. The structures investigated are the cleat and layered structure of coal and the mineral inclusions. Samples of uniform size and shape were prepared from a large block of South African Waterberg coal. The samples were analyzed nondestructively using microfocus X-ray computed tomography then wrapped in cling film and mechanically compressed while the pressure applied was measured. The virtual three-dimensional volume tomograms of the initial sample and the progeny were compared and the changes qualitatively analyzed. Conclusions were drawn as to where the fatal cracks initialized and how the cracks propagated. Particle-size distributions were done to quantify the extent of breakage versus the breakage strength of the sample. It was found that, of all the internal structures, the inherent crack distribution has the biggest influence on breakage and breakage patterns of coal. © 2015 Taylor & Francis Group, LLC.

Cmiel K.,National Center for Nuclear Research | Milczarek J.J.,National Center for Nuclear Research | Bam L.C.,Radiation Science | Fijal-Kirejczyk I.M.,National Center for Nuclear Research | And 2 more authors.
Acta Physica Polonica A | Year: 2013

The results of studies on drying of layers of particulate corundum performed with digital neutron radiography are presented. The statistical analysis of images was employed to reveal main features of the drying process. It is shown that the first period of drying proceeds within the whole body of the sample. Marked signatures of the end of first period of drying were found for sample mass, temperature, average image brightness as well as standard deviation of brightness time evolutions for the system composed of fine grains. The chaotic nature of this period is delineated by a distinct maximum in the standard deviation of sample image brightness. The presence of the drying front moving from the open surface to the sample bottom is proven to be an attribute of the advanced drying period.

Jacobson L.,McGregor Museum | Jacobson L.,Cape Peninsula University of Technology | De Beer F.C.,Radiation Science | Nshimirimana R.,Radiation Science
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

We demonstrate the use of both neutron- and X-ray imaging in two projects. The first project, using both the methods to view the temper in a ceramic sherd in order to model the effect the chemical composition of the temper has on the bulk chemical composition of the sherd showed that X-ray imaging is superior to neutron imaging for a ceramic. The second project, to establish whether apparent incised lines on stone slabs (dated to greater than 180,000 years ago) are natural or artificial, i.e., whether they were deliberately incised or natural, random striations showed conclusively that the incisions are in fact surface manifestations of natural internal fractures in the rock. © 2011 Elsevier B.V. All rights reserved.

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