Centrifuge modelling of the behaviour of pile groups under vertical eccentric load

Annular shaped pile groups are a very common foundation layout for onshore wind turbines and other slender structures. In this study, their performance under vertical loads of moderate to high eccentricity, including moment rotation response and bearing capacity, was investigated by centrifuge testing on small scale physical models embedded in kaolin clay. To identify experimentally the capacity of the examined pile groups under different load paths, the model foundations were loaded monotonically until a clear collapse mechanism was achieved. The testing procedure and the proposed interpretation methodology can be easily adapted to load paths or pile layouts other than those considered in the current study. The experimental data can be adopted as a useful benchmark for mathematical models aimed at predicting the response of pile groups to complex load paths. The results of this testing program can also be used to assess the degree of conservatism of current methods adopted by industry for the design of piled foundations subjected to eccentric loads

Performance of RaCe Instrumentation System in Curved Root Canals: A Comprehensive Analysis by Three Study Methods

In this study, curved maxillary molar root canals were instrumented with RaCe rotary system to evaluate: 1. the occurrence of canal transportation using a radiographic platform; 2. the action of the instruments on the dentin walls, centering ability and canal enlargement by analysis of digital images; and the percentage of regular dentin surfaces and debris within the canal by histological analysis. Ten mesiobuccal roots of extracted human maxillary molars were embedded in acrylic resin and sectioned at the middle and apical thirds. Root canal shaping was performed using the RaCe rotary system at 250 rpm and 1 Ncm torque. Each instrument set was used five times according to a crowndown technique in the following sequence: 40/0.10, 35/0.08, 25/0.06, 25/0.04, 25/0.02 (working length - WL), 30/0.02 (WL) and 35/0.02 (WL). Each instrument was inserted until resistance was felt and then pulled back, followed by brushing movements towards all canal walls. Each specimen was assessed by three study methods: radiographic platform, digitized image assessment and histological analysis. The radiographic platform showed lack of apical transportation. No statistically significant difference (Wilcoxon test, p>0.05) was found between the middle and apical thirds regarding instrument action on dentin walls, centering ability, area of root canal enlargement, percentage of regular dentin surfaces and debris within the root canal. It may be concluded that RaCe system is a suitable method for the preparation of curved root canals, regarding the maintenance of root canal original path, action on dentin walls, canal enlargement and removal of debris from the root canal lumen.Department of Dentistry Positivo University, Curitiba, PRDepartment of Dentistry UFPR - Federal University of Paraná, Curitiba, PRDepartment of Dentistry Universidade Estadual Paulista (UNESP) UNESP, Araraquara, SPDepartment of Dentistry Universidade Estadual Paulista (UNESP) UNESP, Araraquara, S

Orbital apex tumour caused by chronic lymphocytic leukaemia: an unlikely suspect

An 88-year-old woman with a background of chronic lymphocytic leukaemia (CLL) and presented with unilateral ptosis and dull facial pains for 1 month. Examination revealed a complete right-sided ptosis and pupillary dilation. Vision in her right eye was limited to light perception. She had total external ophthalmoplegia. Her corneal reflex was not present in her right eye and she had lost sensation on the right side of her forehead. MRI revealed abnormal enhancement in the right orbital apex extending posteriorly to the sphenoid sinus. The mass invaded the superior orbital fissure, optic canal and cavernous sinus. The lumbar puncture was normal. Owing to the proximity of the mass to the cavernous sinus, it was deemed that surgical excision of the tumour was unsafe; however, it was amenable to biopsy. Histology of the biopsies was consistent with CLL. The patient declined to undergo single high-dose radiotherapy followed by dexamethasone

The challenges associated with laboratory scale physical modelling of high-plasticity spoil materials

Characterisation of spoil (surface mine overburden) material is essential when investigating geotechnical issues associated with the spoil, e.g., for investigating the stability of pit lakes formed with spoil or spoil-structure interaction for any structures built on the spoil as part of sustainable developments. A significant proportion of spoils found across European countries are classified predominantly as silty clay with significant plasticity index and low permeability. In this paper, the difficulties associated with laboratory testing of highly plastic spoil materials obtained from different post-mining sites within Europe are discussed. The issues associated with small-scale laboratory testing of field spoil samples, development of an equivalent spoil for performing physical modelling tests, and the difficulties of centrifuge tests with spoil models are discussed in detail