Acute Respiratory Obstruction due to Accidental Inhalation of Perlite: A Novel Mechanism for Upper Airway Occlusion with Cast Formation.

A 56-year-old man died following a fall resulting in complete submersion into a deep pit containing insulation material, expanded perlite. The most striking finding at autopsy was of impacted, moist pale yellow perlite that extended from the epiglottis into the main bronchi resulting in complete obstruction of the larger and smaller airways with cast formation. Perlite inhalation differs from inhalation of inert materials such as sand and wheat due to its hygroscopic properties and ability to expand forming an occlusive cast. Subsequent analyses of perlite from the worksite and within the airways indicated that hydration of perlite and adsorption of organic molecules into the perlite glass flakes had formed an interlocking, three-dimensional structure that was likely responsible for triggering a coagulation-flocculation process causing strong cohesion between the aggregates of glass flakes. This unique mechanism was likely responsible for the formation of the plug of perlite that obstructed the upper airway.

The use of mid-infrared diffuse reflectance spectroscopy for acid sulfate soil analysis.

Good management of sulfide minerals and sulfuric acid in Acid Sulfate Soils (ASS) requires cost-effective rapid analytical data for their characterisation. However, the determination of properties in ASS samples using traditional laboratory techniques is expensive and time consuming. Excessive delays in analysis risks sample changes from oxidation. Mid-infrared (MIR) spectroscopy with multivariate regression offers a quicker and cheaper surrogate. This manuscript reports the prediction of some of the following key soil parameters in ASS characterisation using benchtop (Perkin Elmer) and handheld (ExoScan) diffuse reflectance MIR Fourier transform (DRIFT) spectrometers: Total Organic Carbon (TOC), Titratable Actual Acidity (TAA), Extractable Sulfate Sulfur (ESS), Reduced Inorganic Sulfur (RIS), Retained Acidity (RA), Acid Neutralising Capacity (ANC), and Lime Calculation (LC). Three sets of representative ASS soil profiles, comprising 132 samples from hyposulfidic, hypersulfidic and sulfuric materials, and covering a wide range of environments in South Australia were scanned under laboratory conditions. These were combined with reference laboratory data in partial least squares regression (PLSR) calibration models. The calibrations were validated by leave-one-out cross validation, with a further test set available for validation. Predictions with coefficient of determination (R2) > 0.75, were obtained for TOC (0.95), TAA (0.88), RIS (0.86), LC (0.76) and ANC (0.76), but models for ESS (0.66) and RA (0.41) were less satisfactory. The handheld spectrometer performed similarly to the benchtop spectrometer in terms of PLSR prediction accuracies with the potential for in-field sampling. Results thus confirmed the possibility of using MIR spectroscopy for the rapid and cost-effective characterisation of ASS.

Scientific evidence for the identification of an Aboriginal massacre at the Sturt Creek sites on the Kimberley frontier of north-western Australia.

Archival research into episodes of frontier violence in the Kimberley region of Western Australia indicate that the bodies of Aboriginal victims of massacres were frequently incinerated following the event. This paper presents the results of a scientific investigation of a reported massacre at Sturt Creek where burnt bone fragments were identified in two adjacent sites and documents the archaeological signatures associated with the sites. The methodology used to undertake the project brought together three systems of knowledge: the oral testimonies of the descent group originating from a sole adult survivor of the massacre; archival, historical and scientific research. An archaeological survey defined the two distinct sites containing hundreds of fragile bone fragments; a third site was found to be highly disturbed. Scientific investigations included macroscopic and microscopic examination of selected bone fragments by an anatomical pathologist and a zooarchaeologist and X-ray diffraction analysis of sixteen bone fragments. The anatomical pathologist and zooarchaeologist undertook macroscopic and microscopic examinations of selected bone samples to identify morphological evidence for human origin. It was concluded that three bone fragments examined may have been human, and two of the fragments may have been from the vault of a skull. It was concluded that the likelihood of them being human would be strengthened if it was found that the three samples had been subjected to high temperatures. X-ray diffraction analysis of 16 bone fragments provided this evidence. All fragments showed sharp hydroxylapatite peaks (crystallite sizes 9882nm and 597nm respectively) and all had been subjected to extreme temperatures of either 600°C for more than 80h, 650°C for more than 20h, 700°C for more than 4h or 800°C for more than 1h. XRD analyses were also done on bone samples collected from three cooking hearths at three different archaeological sites. It was found that two of the three samples had been exposed to substantially lower temperatures for a short time period. It was concluded that there was strong pathological and archaeological evidence that the bone fragments were human in origin, but that the evidence was not conclusive. This research also identified archaeological signatures for the identification of massacre sites in similar Australian environments and circumstances.

Patterns produced when soil is transferred to bras by placing and dragging actions: The application of digital photography and image processing to support visible observations.

A series of soil transference experiments (STEs) were undertaken to determine whether patterns identified in laboratory experiments could also be recognised at a simulated crime scene in the field. A clothed 55kg human rescue dummy dressed in a padded bra was either dragged or merely placed on a soil surface at sites with natural and anthropogenic soil types under both wet and dry soil conditions. Transfer patterns produced by dragging compared favourably with those of laboratory experiments. Twelve patterns were identified when a clothed human rescue dummy was dragged across the two soil types in the field. This expanded the original set of eight soil transfer patterns identified from dragging weighted fabric across soil samples in the laboratory. Soil transferred by placing the human rescue dummy resulted in a set of six transfer patterns that were different to those produced by dragging. By comparing trace soil patterns transferred to bras using each transfer method, it was revealed that certain transfer patterns on bras could indicate how the fabric had made contact with a soil surface. A photographic method was developed for crime scene examiners to capture this often subtle soil evidence before a body is transported or the clothing removed. This improved understanding of the dynamics of soil transference to bras and related clothing fabric may assist forensic investigators reconstruct the circumstances of a variety of forensic events.

Soil transference patterns on bras: Image processing and laboratory dragging experiments.

In a recent Australian homicide, trace soil on the victim's clothing suggested she was initially attacked in her front yard and not the park where her body was buried. However the important issue that emerged during the trial was how soil was transferred to her clothing. This became the catalyst for designing a range of soil transference experiments (STEs) to study, recognise and classify soil patterns transferred onto fabric when a body is dragged across a soil surface. Soil deposits of interest in this murder were on the victim's bra and this paper reports the results of anthropogenic soil transfer to bra-cups and straps caused by dragging. Transfer patterns were recorded by digital photography and photomicroscopy. Eight soil transfer patterns on fabric, specific to dragging as the transfer method, appeared consistently throughout the STEs. The distinctive soil patterns were largely dependent on a wide range of soil features that were measured and identified for each soil tested using X-ray Diffraction and Non-Dispersive Infra-Red analysis. Digital photographs of soil transfer patterns on fabric were analysed using image processing software to provide a soil object-oriented classification of all soil objects with a diameter of 2 pixels and above transferred. Although soil transfer patterns were easily identifiable by naked-eye alone, image processing software provided objective numerical data to support this traditional (but subjective) interpretation. Image software soil colour analysis assigned a range of Munsell colours to identify and compare trace soil on fabric to other trace soil evidence from the same location; without requiring a spectrophotometer. Trace soil from the same location was identified by linking soils with similar dominant and sub-dominant Munsell colour peaks. Image processing numerical data on the quantity of soil transferred to fabric, enabled a relationship to be discovered between soil type, clay mineralogy (smectite), particle size and soil moisture content that would not have been possible otherwise. Soil type (e.g. Anthropogenic, gravelly sandy loam soil or Natural, organic-rich soil), clay mineralogy (smectite) and soil moisture content were the greatest influencing factors in all the dragging soil transference tests (both naked eye and measured properties) to explain the eight categories of soil transference patterns recorded. This study was intended to develop a method for dragging soil transference laboratory experiments and create a baseline of preliminary soil type/property knowledge. Results confirm the need to better understand soil behaviour and properties of clothing fabrics by further testing of a wider range of soil types and clay mineral properties.