Once upon a twine: The Donna Steele murder investigation and an improved methodology for the comparison of synthetic twine.

In 2017 Cooktown resident Donna Steele was murdered and the case remained unsolved for more than a year. The forensic evidence from the investigation included two lengths of synthetic twine and a new protocol for the comparison of twine was developed to enhance the potential value of any evidence. The method was developed using 23 samples of similar twine collected across Australia. Traditional methods of physical and microscopic comparisons and polymer analysis by infrared spectroscopy were retained. Micro-spectrophotometry was used as an objective assessment of colour and was able to identify five groupings within the background samples. Measurements of hydrogen and carbon stable isotopic composition provided further delineation of the background samples. Combining traditional methods with micro-spectrophotometry and stable isotope measurements, the two case samples were found to be distinct from the background population and were indistinguishable when compared to each other.

Characterization of the Double Bond Conversion of Acrylic Resins for 3D Printing of Dental Prostheses.

Characterization of the double bond conversion of acrylic resins is considered critical in the evaluation of dental materials due to the propensity of end-use devices to accumulate residual monomer and degradation products that can cause local and systemic side effects in high doses. In this study, the authors examine two different acrylic-based photopolymers indicated for 3D printing of dental prostheses using Fourier transform infrared spectroscopy: a denture base material comprising ≥75% ethoxylated bisphenol A dimethacrylate, and a crown-and-bridge material composed of >60% proprietary methacrylic oligomer and 15%-25% 2-hydroxyethyl methacrylate. Infrared spectroscopy data showed a conversion rate (240 s) of 52.37 ± 1.05% for the former material and 45.36 ± 1.41% for the latter. Compared to traditional acrylic resins, both materials exhibited a considerably lower degree of conversion. With limited scientific data available on the clinical performance of 3D printing materials in general, additional evidence is needed to ascertain their in vivo performance in the long-term.

Constituents of "teabacco": A forensic analysis of cigarettes made from diverted nicotine replacement therapy lozenges in smoke-free prisons.

Following the implementation of prison smoke-free policies, there have been reports of prisoners creating substitute cigarettes made from nicotine replacement therapy patches or lozenges infused with tea leaves ("teabacco"). No studies have analyzed the chemical constituents of teabacco made from nicotine lozenges, so as to document any potential related health hazards. Teabacco samples were made by a participant who reported creating teabacco while incarcerated in a smoke-free prison in Queensland, Australia, and the process was video-recorded for replication in a laboratory. A simple linear smoking system captured the teabacco smoke for analysis. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to analyze elemental composition and gas chromatography coupled with a mass spectrometer (GC-MS) analyzed the captured smoke using the National Institute of Standards and Technology mass spectral library. Analyses determined that quantities of copper, aluminum, and lead concentrations, and levels of inhaled total particulate matter, were above recommended guidelines for safe ingestion. Analysis of teabacco smoke using GC-MS identified potentially toxic compounds catechol and nicotine. However, our findings show that smoking this form of teabacco is less harmful than smoking teabacco made from nicotine patches, or smoking traditional tobacco cigarettes. Considering the limited potential health harm of smoking teabacco made from lozenges, and that nicotine lozenges represent the only form of smoking cessation support for individuals entering smoke-free prisons, we caution against the removal of nicotine lozenges from Queensland's prisons, at least until further research directly establishes health harms associated with this form of teabacco.

Toxicological assessment of additively manufactured methacrylates for medical devices in dentistry.

The paucity of information on the biological risks of photopolymers in additive manufacturing is a major challenge for the uptake of the technology in the construction of medical devices in dentistry. In this paper, the biocompatibility of methacrylates for denture bases, splints, retainers and surgical guides were evaluated using the innovative zebrafish embryo model, which is providing a high potential for toxicity profiling of photopolymers and has high genetic similarity to humans. Toxicological data obtained confirmed gradations of toxicity influenced by ethanol treatment, exposure scenarios and extraction vehicles. In direct exposure tests, juvenile fish exposed to non-treated methacrylates in ultrapure water showed accelerated toxicity endpoints compared to fish in transparent E3 medium. Similarly, toxic extracts induced mostly acute responses (embryonic mortality) in contrast to cumulative chronic (sublethal and teratogenic effects) in direct exposure. Methacrylates composed of >60% Ethoxylated bisphenol A dimethacrylate produced a relatively lower conversion rate in FTIR spectroscopy, but were safe in zebrafish bioassays after ethanol treatment. The study affirms that biocompatibility was influenced primarily by physico-chemical characteristics of the materials, which subsequently influenced their residual monomer content before and after immersion in ethanol. Given the precautionary implications of the study, we propose a 3-tiered approach i.e. using approved materials, apposite manufacturing parameters and post-processing techniques that together guarantee optimal results for medical devices. STATEMENT OF SIGNIFICANCE: This study is timely and relevant since there is limited published literature that precisely describes the toxicological properties of additively manufactured methacrylates despite their increased popularity for medical devices. While it is generally accepted that the zebrafish excels as a model system for developmental toxicity, a further examination of its utility in this study using different protocols provides basis for its consideration and adoption at a crucial time when there is a lack of consensus regarding the most suited biological assessment methods for medical devices.

'Teabacco': Smoking of nicotine-infused tea as an unintended consequence of prison smoking bans.

INTRODUCTION AND AIMS: Following the introduction of smoke-free policies in prisons in several countries, there have been anecdotal reports of prisoners creating cigarettes by mixing nicotine patches or lozenges with tea leaves ('teabacco'). Among a sample of people recently released from smoke-free prisons in Queensland, Australia, the aims of this study were to explore the perceived popularity of teabacco use, motivations for its use and describe the process of creating teabacco to identify potential associated health risks. DESIGN AND METHODS: This study used a mixed-methods design. Eighty-two people recently released from prison in Queensland, Australia completed surveys at parole offices measuring teabacco use while incarcerated. Twenty-one teabacco smokers took part in follow-up, qualitative interviews to explore survey responses in greater depth. RESULTS: The majority of survey participants (57%) reported smoking teabacco while incarcerated, with 37% smoking teabacco frequently (> once per week). Teabacco use was primarily motivated by cigarette cravings. Participants described the perceived inevitability of prisoners finding substitutes for tobacco. Multivariate analyses found that self-rated poor physical health, having been incarcerated five or more times, experiencing cigarette cravings while incarcerated, and use of illicit drugs while incarcerated were positively associated with frequent teabacco use in prison. DISCUSSION AND CONCLUSIONS: Our findings suggest that teabacco use has become common practice in Queensland's smoke-free prisons. Correctional smoking bans are an important public health initiative but should be complemented with demand and harm reduction measures cognisant of the risk environment.