Performance characteristics of bitumen-emulsion stabilized mine-haul roads

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: In the past, mine haul roads were constructed based on local mining knowledge which often re- sulted in unpredictable road conditions and high vehicle- and road maintenance costs. It has be- come crucial to reduce both operating costs and road maintenance costs to remain profitable. Re- cently, a viable long term and cost-effective solution was introduced by incorporating of Bitumen Stabilized Material (BSM) on Mine Haul Road Structures. BSM incorporated into Pavement Structures have been proven to increase the life span of the road structure. Also, bitumen stabilization creates less moisture susceptible base layers which allows the given layer to be more durable under repeated loading. However, the durability of BSM tech- nology should also be taken into consideration and how it would benefit the mining industry. To create a more standardized implementation of bitumen stabilization in mine haul roads, this re- search aims to investigate correlations between the performance and material characterisation. Also, this research aims to provide insight into the expected bearing capacity of the bitumen sta- bilized base layer through various structural testing methods such as Indirect Tensile Strength (ITS) and Dynamic- as well as Monotonic Triaxial testing. Preliminary ITS results suggest that the current mix design under consideration meets the mini- mum requirements of a BSM2 material classification for both base layers on Kansanshi and Ka- lumbila at an average residual bitumen content of 2.2 % and 1.3 % respectively. Further monotonic triaxial analysis on the Kansanshi base indicates that the mix design has a cohesion of 240 kPa with an accompanying friction angle of 41.8 º. These parameters are in line with BSM1 classifica- tion limits. However, further analysis is required on the retained cohesion classification limits. Dynamic triaxial tests performed on the Kansanshi base also yields the BSM Base Layer’s Resil- ient Modulus to be in the order of 2500 MPa. Permeability testing on both Kansanshi- and Kalumbila Trolley Ramp cores evaluates durability of the haul road surfacing, however, the implementation of the dust palliative layer does improve the water-resistance of the BSM Layer. Water is still able to penetrate through the palliative layer due to surface cracking and irregularities. Through the material composition analysis, the residual binder content for Kansanshi and Kalumbila is 2.2 % and 1.3 % respectively. Also, through grad- ing analysis on both Mines’ Trolley Ramp cores, excess fine material was observed between the 2.0 mm to 0.075 mm grading fraction. By making use of the performance- and material composition results the expected Mechanistic- Empirical (ME) pavement life design for both Kansanshi and Kalumbila Trolley Ramp cores is modelled. The pavement life model yields that the BSM Base Layers can withstand 50+ Million Equivalent Standard Axles (MESAs) under repeated loading. Also, the stress distribution between the Base layer and underlying Subbase structure indicates that both Kansanshi and Kalumbila have well-balanced pavement structures.AFRIKAANSE OPSOMMING: In die verlede is mynafvoerpaaie gebou op grond van plaaslike kennis wat dikwels tot onvoorspel- bare padtoestande en hoë voertuig- en padinstandhoudingskoste gelei het. Weens ekonomiese beperkings het dit noodsaaklik geword om beide bedryfskoste en padinstandhoudingskoste te ver- minder. In onlangse jare is die inkorporering van bitumen gestabiliseerde materiaal op mynafvoer- padstrukture as 'n lewensvatbare langtermynkoste-effektiewe oplossing beskou. Bewyse is gelewer dat die inkorporeering van BSM materiaal in ‘n plaveisels struktuur die lew- ensduur van daardie struktuur verleng. Bitumen emulsie stabilisering skep ook 'n kroon laag wat minder water deurlaatbaar is, wat in ruil die laag meer duursaam onder herhaalde spannings kragte. Kan BSM-tegnologie mynafvoerpaaie bevoordeel? Om 'n meer gestandaardiseerde implementer- ing van bitumenstabilisering in mynafvoerpaaie te skep, het hierdie navorsing ten doel om korrelasies tussen die plaveisel duursaamheid en materiële karakterisering te ondersoek. Hierdie navorsing het ook ten doel om insig te gee in die verwagte dravermoë van die bitumen gestabi- liseerde kroon laag. Voorlopige resultate dui daarop dat die huidige mengsel ontwerp voldoen aan die klassifikasie vereistes van 'n BSM2 materiaal vir beide basis lae op Kansanshi en Kalumbila met gemiddelde residuele bitumen inhoude van 2.2 % en 1.3 % onderskeidelik. Verder is die skuifparameters vir die Kansanshi kroon laag bepaal as 240 kPa vir die kohesie en 41.8 º vir die wrywingshoek. Hierdie skuifsterkte-eienskappe stem ooreen met die standaard BSM1 skuifparameters. Verdere analise word egter vereis om die behoue kohesie te bepaal. Die dienamiese drie-assige toets wat op die Kansanshi kroon laag uitgevoer is, het bepaal dat die veerkragmodulus van die kroon laag in die orde van 2500 MPa is. Deurlaatbaarheidstoetsing op beide die Kansanshi- en Kalumbila-myn evalueer duursaamheid van die kroonlaag, maar die implementering van die stof palliatief laag is bewys om die weerstand van water in die BSM kroon laag te verbeter. Water kan steeds die palliatief laag indring deur op- pervlakkige krake en onreëlmatighede op die oppervlakte. Deur die materiaalsamestellingsanalise is die oorblywende bitumeninhoud vir Kansanshi en Kalumbila bepaal as 2.21% en 1.29% onderskeidelik. Verdere graderingsanalise op beide mynafvoerpaaie se oorblywende aggregaat, is 'n gebrek aan fyn materiaal waargeneem tussen die 2.0 mm tot 0.075 mm fraksie.Master

Evaluation of biocontrol agents for grapevine pruning wound protection against trunk pathogen infection.

Trunk diseases of grapevine are caused by numerous pathogens, including Eutypa lata, Phaeomoniella chlamydospora, and species of Botryosphaeriaceae (incl. Botryosphaeria and aggregate genera), Phomopsis and Phaeoacremonium. Since infections occur mainly through pruning wounds, that have been shown by previous research to stay susceptible for up to 16 weeks after pruning, long-term pruning wound protection is required for prevention of infection. This study evaluated several biocontrol agents against a range of trunk disease pathogens in dual plate laboratory trials to determine macroscopic and microscopic interactions. The biocontrol agents had a substantial effect on all the pathogens, with a wide range of macroscopic and microscopic interactions observed. The best performing biocontrol agents were tested in two field trials. Fresh pruning wounds were treated with benomyl, Trichoderma products (Biotricho®, Vinevax® and ECO 77®) and isolates (USPP-T1 and -T2, identified as T. atroviride) and Bacillus subtilis. Seven days after treatment the pruning wounds were inoculated by spraying with spore suspensions of Neofusicoccum australe, N. parvum, Diplodia seriata, Lasiodiplodia theobromae, Eutypa lata, Phaeomoniella chlamydospora or Phomopsis viticola. Eight months after inoculation, the treatments were evaluated by isolation onto potato dextrose agar. The efficacy of the biocontrol agents was in most cases similar or superior to that observed for benomyl. Isolate USPP-T1, in particular, was very effective, reducing incidence of Ph. viticola, E. lata, Pa. chlamydospora, N. australe, N. parvum, D. seriata and L. theobromae by 69, 76, 77, 78, 80, 85 and 92%, respectively. This is the first report of biological protection of grapevine pruning wounds against this group of grapevine trunk disease pathogens

The SKA Dish SPF and LMC Interaction Design: Interfaces, Simulation, Testing and Integration

The Square Kilometre Array (SKA) project is responsible for developing the SKA Observatory, the world's largest radio telescope ever built: eventually two arrays of radio antennas - SKA1-Mid and SKA1-Low - will be installed in the South Africa's Karoo region and Western Australia's Murchison Shire respectively, each covering a different range of radio frequencies. In particular, the SKA1-Mid array will comprise of 133 15m diameter dish antennas observing in the 350 MHz-14 GHz range, each locally managed by a Local Monitoring and Control (LMC) system and remotely orchestrated by the SKA Telescope Manager (TM) system. All control system functionality run on the Tango Controls platform. The Dish Single Pixel Feed (SPF) work element will design the combination of feed elements, orthomode transducers (OMTs), and low noise amplifiers (LNAs) that receive the astronomical radio signals. Some SPFs have cryogenically cooled chambers to obtain the sensitivity requirements. This paper gives a status update of the SKA Dish SPF and LMC interaction design, focusing on SPF, LMC simulators and engineering/operational user interfaces, prototypes being developed and technological choices

Ground beetle assemblages in Beijing’s new mountain forests

Mature forests have been almost completely destroyed in China’s northern regions, but this has been followed by large-scale reforestation in the wake of environmental degradation. Although future forest plantations are expected to expand over millions of hectares, knowledge about the ecology and biodiversity of China’s replanted forests remains very limited. Addressing these knowledge gaps, we recorded ground beetle (Coleoptera: Carabidae) communities in five secondary forest types: plantations of Chinese Pine (Pinus tabulaeformis) and Prince Rupprecht’s Larch (Larix principis-rupprechtii), Oak (Quercus wutaishanica) and Asian White Birch (Betula platyphylla) woodlands, and naturally regenerated mixed forest. Species richness peaked in mixed forests, while pine and oak woodlands harboured discrete communities of intermediate species richness. Oak, pine and mixed forest habitats also showed high levels of species turnover between plots. Canopy closure was an important factor influencing ground beetle assemblages and diversity, and a number of forest specialist species only occurred in pine or oak forests. We believe that some forest specialists have survived earlier deforestation and appear to be supported by new plantation forests, but maintenance of secondary native oak and mixed forests is crucial to safeguard the overall species pool

Contrasting evolutionary history, anthropogenic declines and genetic contact in the northern and southern white rhinoceros (Ceratotherium simum)

The white rhinoceros (Ceratotherium simum) has a discontinuous African distribution, which is limited by the extent of sub-Saharan grasslands. The southern population (SWR) declined to its lowest number around the turn of the nineteenth century, but recovered to become the world's most numerous rhinoceros. In contrast, the northern population (NWR) was common during much of the twentieth century, declining rapidly since the 1970s, and now only two post-reproductive individuals remain. Despite this species's conservation status, it lacks a genetic assessment of its demographic history. We therefore sampled 232 individuals from extant and museum sources and analysed ten microsatellite loci and the mtDNA control region. Both marker types reliably partitioned the species into SWR and NWR, with moderate nuclear genetic diversity and only three mtDNA haplotypes for the species, including historical samples. We detected ancient interglacial demographic declines in both populations. Both populations may also have been affected by recent declines associated with the colonial expansion for the SWR, and with the much earlier Bantu migrations for the NWR. Finally, we detected post-divergence secondary contact between NWR and SWR, possibly occurring as recently as the last glacial maximum. These results suggest the species was subjected to regular periods of fragmentation and low genetic diversity, which may have been replenished upon secondary contact during glacial periods. The species's current situation thus reflects prehistoric declines that were exacerbated by anthropogenic pressure associated with the rise of late Holocene technological advancement in Africa. Importantly, secondary contact suggests a potentially positive outcome for a hybrid rescue conservation strategy, although further genome-wide data are desirable to corroborate these results

Contrasting evolutionary history, anthropogenic declines and genetic contact in the northern and southern white rhinoceros (Ceratotherium simum)

The white rhinoceros (Ceratotherium simum) has a discontinuous African distribution, which is limited by the extent of sub-Saharan grasslands. The southern population (SWR) declined to its lowest number around the turn of the nineteenth century, but recovered to become the world's most numerous rhinoceros. In contrast, the northern population (NWR) was common during much of the twentieth century, declining rapidly since the 1970s, and now only two post-reproductive individuals remain. Despite this species's conservation status, it lacks a genetic assessment of its demographic history. We therefore sampled 232 individuals from extant and museum sources and analysed ten microsatellite loci and the mtDNA control region. Both marker types reliably partitioned the species into SWR and NWR, with moderate nuclear genetic diversity and only three mtDNA haplotypes for the species, including historical samples. We detected ancient interglacial demographic declines in both populations. Both populations may also have been affected by recent declines associated with the colonial expansion for the SWR, and with the much earlier Bantu migrations for the NWR. Finally, we detected post-divergence secondary contact between NWR and SWR, possibly occurring as recently as the last glacial maximum. These results suggest the species was subjected to regular periods of fragmentation and low genetic diversity, which may have been replenished upon secondary contact during glacial periods. The species's current situation thus reflects prehistoric declines that were exacerbated by anthropogenic pressure associated with the rise of late Holocene technological advancement in Africa. Importantly, secondary contact suggests a potentially positive outcome for a hybrid rescue conservation strategy, although further genome-wide data are desirable to corroborate these results

Pansteatitis of unknown etiology associated with large-scale nile crocodile (Crocodylus Niloticus) mortality in Kruger National Park, South Africa : pathologic findings

Annual mortality events in Nile crocodiles (Crocodylus niloticus) in the Olifants River Gorge in Kruger National Park, South Africa, were experienced between 2008 and 2012, during which at least 216 crocodiles died. Live crocodiles were lethargic. Necropsy examination of 56 affected crocodiles showed dark yellow-brown firm nodules in both somatic fat and the abdominal fat body. In all of the 11 crocodiles submitted for histology, degenerative, necrotic, and inflammatory changes supported a diagnosis of steatitis in both fat types. Crocodiles are apex predators in this anthropogenically changed aquatic ecosystem that is used by humans upstream and downstream from the park for domestic, agricultural, fishing, and recreational purposes. This pathologic review of pansteatitis in crocodiles in the Olifants River system was part of a broad multidisciplinary research program. To date, no definitive causative agent has been identified. Epidemiologic evidence suggests that this event may have been a one-time event with long-standing repercussions on the health of the crocodiles. Pathologic findings are rarely documented in wild crocodilians. This study also reports on other conditions, including the presence of coccidian oocysts, capillarid and filaroid nematodes, digenetic trematodes, and pentastomes.Histopathologic processing was funded by the U.S. Fish and Wildlife Service.http://zoowildlifejournal.comam201

Consensus recommendations for patient-centered therapy in mild-to-moderate ulcerative colitis: the i Support Therapy–Access to Rapid Treatment (iSTART) approach

Symptomatic ulcerative colitis (UC) can be a chronic, disabling condition. Flares in disease activity are associated with many of the negative impacts of mild-to-moderate UC. Rapid resolution of flares can provide benefits to patients and healthcare systems. i Support Therapy–Access to Rapid Treatment (iSTART) introduces patient-centered care for mild-to-moderate UC. iSTART provides patients with the ability to self-assess symptomology and self-start a short course of second-line treatment when necessary. An international panel of experts produced consensus statements and recommendations. These were informed by evidence from systematic reviews on the epidemiology, mesalazine (5-ASA) treatment, and patient use criteria for second-line therapy in UC. Optimized 5-ASA is the first-line treatment in all clinical guidelines, but may not be sufficient to induce remission in all patients. Corticosteroids should be prescribed as second-line therapy when needed, with budesonide MMX® being a preferred steroid option. Active involvement of suitable patients in management of UC flares has the potential to improve therapy, with patients able to show good accuracy for flare self-assessment using validated tools. There is a place in the UC treatment pathway for an approach such as iSTART, which has the potential to provide patient, clinical and economic benefits

Efficacy of Single-Dose and Triple-Dose Albendazole and Mebendazole against Soil-Transmitted Helminths and Taenia spp.: A Randomized Controlled Trial

BACKGROUND: The control of soil-transmitted helminth (STH) infections currently relies on the large-scale administration of single-dose oral albendazole or mebendazole. However, these treatment regimens have limited efficacy against hookworm and Trichuris trichiura in terms of cure rates (CR), whereas fecal egg reduction rates (ERR) are generally high for all common STH species. We compared the efficacy of single-dose versus triple-dose treatment against hookworm and other STHs in a community-based randomized controlled trial in the People's Republic of China. METHODOLOGY/PRINCIPAL FINDINGS: The hookworm CR and fecal ERR were assessed in 314 individuals aged </=5 years who submitted two stool samples before and 3-4 weeks after administration of single-dose oral albendazole (400 mg) or mebendazole (500 mg) or triple-dose albendazole (3x400 mg over 3 consecutive days) or mebendazole (3x500 mg over 3 consecutive days). Efficacy against T. trichiura, Ascaris lumbricoides, and Taenia spp. was also assessed. ALBENDAZOLE CURED SIGNIFICANTLY MORE HOOKWORM INFECTIONS THAN MEBENDAZOLE IN BOTH TREATMENT REGIMENS (SINGLE DOSE: respective CRs 69% (95% confidence interval [CI]: 55-81%) and 29% (95% CI: 20-45%); triple dose: respective CRs 92% (95% CI: 81-98%) and 54% (95% CI: 46-71%)). ERRs followed the same pattern (single dose: 97% versus 84%; triple dose: 99.7% versus 96%). Triple-dose regimens outperformed single doses against T. trichiura; three doses of mebendazole - the most efficacious treatment tested - cured 71% (95% CI: 57-82%). Both single and triple doses of either drug were highly efficacious against A. lumbricoides (CR: 93-97%; ERR: all <99.9%). Triple dose regimens cured all Taenia spp. infections, whereas single dose applications cured only half of them. CONCLUSIONS/SIGNIFICANCE: Single-dose oral albendazole is more efficacious against hookworm than mebendazole. To achieve high CRs against both hookworm and T. trichiura, triple-dose regimens are warranted. CONCLUSIONS/SIGNIFICANCE: Single-dose oral albendazole is more efficacious against hookworm than mebendazole. To achieve high CRs against both hookworm and T. trichiura, triple-dose regimens are warranted. TRIAL REGISTRATION: www.controlled-trials.comISRCTN4737502

Forty years of carabid beetle research in Europe - from taxonomy, biology, ecology and population studies to bioindication, habitat assessment and conservation

Volume: 100Start Page: 55End Page: 14