This paper highlights how micro-CT was used to assist in the investigation of hybrid firearms constructed using a mixture of plastic and metal components, as a complementary technique to the physical examination performed by firearms experts. In recent years, there has been an increase in the complexity and sophistication of 3D printed and hybrid firearm designs. This was also the case in the investigation presented herein, with the firearms seized demonstrating a step change in the threat level they pose through their complexity. Thus, we describe how data produced from micro-CT scans was used to help firearms experts study the viability and mechanics of two hybrid weapons prior to dismantling and test-firing. This process aided experts in determining whether components were 3D printed or manufactured through other means, whilst ensuring that a digital record (digital twin) was retained in case evidence was damaged during testing. Finally, we show how the data was presented visually through animations and as evidence in court. This proved to be imperative when communicating to the judge, jury, and wider investigating teams, the complex multiple components and mechanisms within the firearms.

The impact of broaching and uncemented implantation on bone density during total hip arthroplasty (THA) remains unclear. Previous studies have typically examined extracted bone sections, which may not directly correlate with outcomes in human hip systems. This study aimed to evaluate bone density changes resulting from broaching and uncemented implantation using micro-computed tomography (μCT) on cadaveric samples. An in-house density calibration phantom (DCP) was developed by validating the densities of polymer inserts through mass and volume measurements. Its performance was then evaluated using lamb bone in comparison with a commercial DCP (QRM-50124). The sensitivity of density predictions to μCT scan parameters was also evaluated with the lamb bone. Additionally, density predictions from medical-CT and μCT scans were compared using the in-house DCP. Finally, uncemented THA procedures were performed on three cadaveric femurs, each undergoing three μCT scans at various surgical stages to assess changes in bone density. The density predictions obtained using the in-house DCP achieved an accuracy of ±0.097 g/cc compared to QRM-50124, with a precision of ±0.052 g/cc. The sensitivity to changes in μCT scan parameters was ±0.022 g/cc. Notably, density predictions from medical-CT and μCT scans were similar, particularly in cortical bone. Broaching and implantation led to an average increase in bone density of 0.137 g/cc, which was attributed to the accumulation of bone debris around the bone-implant interface. This accumulation raised the bone volume fraction, ranging from 3.31% to 20.69%, which acts as an autograft. These measurements have been made for the first time using a µCT and an in-house DCP.

Child abuse is a serious concern that can cause the death of a child. In such cases the medico-legal evidence is often pivotal but complex, drawing across multiple medical disciplines and techniques. One key specialism is histopathology, which is considered the gold standard for estimating the age of individual fractures. Another is micro-CT imaging, which can visualise the location of trauma across the body. This case report demonstrates how micro-CT was used to contextualise the histological evidence in the Criminal Justice Proceedings of a fatal child abuse case. This was achieved by overlaying the aged fracture evidence from histopathology onto the visuals rendered from micro-CT imaging. The case was a suspected child abuse of a deceased 1-month old infant who was reported unresponsive by their parents. The child was taken to hospital where they were pronounced dead. Suspicion was raised and post-mortem imaging confirmed head trauma and rib fractures, and the case was escalated for a forensic investigation. This case report details how the micro-CT imaging was merged with the gold standard of histopathology for visualisation of trauma, and how the court presentation was planned alongside Senior Investigating Officers and various medical experts. The presentation was used in court by the histopathologist to present the evidence. The resulting presentation provided additional clarity to jury members regarding the location, severity, frequency, and timings of the injuries. From the perspective of the investigating police force, the resulting presentation was crucial in ensuring understanding of the medico-legal evidence of how the infant died. The prosecuting lawyer noted that combining the histological and micro-CT evidence in this way allowed the evidence to be presented in a sensitive, clear, and impactful manner.

Molecular flavins are one of the most versatile photocatalysts. They can coordinate single and multiple electron transfer processes, gift hydrogen atoms, form reversible covalent linkages that support group transfer mechanisms,...

BACKGROUND:The stability of uncemented implants during total hip arthroplasty (THA) depends on bone compaction and the bone-implant contact area achieved during the surgical process, particularly during broaching and implantation. However, the evaluation of these factors in actual hip is limited through experimental studies. Therefore, the aim of this study was to quantify bone compaction, and the bone-implant contact area achieved during uncemented THA through a μCT-based cadaveric study of three femur samples. METHODS:Three cadaveric femur samples underwent uncemented THA, with μCT scans conducted at intermediate surgical steps. The bone compaction resulting from the surgical process was quantified using two parameters: (a) displacement and strain induced using Digital Volume Correlation (DVC), (b) changes in bone volume fraction (BV/TV) around the bone-implant interface. Furthermore, the bone-implant contact, and its location were evaluated, including an assessment of the robustness and sensitivity of the measurements. RESULTS:The DVC showed that the trabecular bone deformed plastically, with a displacement of 0.09 ± 0.13 mm, a Von-Mises strain of 7082.28 ± 9162.73 με due to the surgical process. Broken trabecular bone accumulated around the bone-implant interface, increasing BV/TV from 3.31 % to 20.69 %. Bone-implant contact (BIC) was limited, ranging from 3.05 % to 5.22 %, but 75.26 %-82.27 % of the maximum potential contact area (PBICA) was achieved. All samples established a three-point contact, and sensitivity analysis revealed a robust BIC calculation with minimal variability of ±0.87 %. CONCLUSION:The findings offer important insights into bone-implant behaviour during the uncemented THA process. These insights could be useful for physics-based pre-surgical planning to evaluate the stability of uncemented implants and help surgeons choose the most appropriate implants for their patients.

Eumelanin is a natural pigment found in many organisms that provides photoprotection from harmful UV radiation. As a redox-active biopolymer, the structure of eumelanin is thought to contain different redox states of quinone, including catechol subunits. To further explore the excited state properties of eumelanin, we have investigated the catechol/o-quinone redox couple by spectroelectrochemical means, in a pH 7.4 aqueous buffered solution, and using a boron doped diamond mesh electrode. At pH 7.4, the two proton, two electron oxidation of catechol is promoted, which facilitates continuous formation of the unstable o-quinone product in solution. Ultrafast transient absorption (femtosecond to nanosecond) measurements of o-quinone species involve initial formation of an excited singlet state followed by triplet state formation within 24 ps. In contrast, catechol in aqueous buffer leads to formation of the semiquinone radical Delta t>500 ps. Our results demonstrate the rich photochemistry of the catechol/o-quinone redox couple and provides further insight into the excited state processes of these key building blocks of eumelanin.

Many photoactivated processes involve a change in oxidation state during the reaction pathway and formation of highly reactive photoactivated species. Isolating these reactive species and studying their early-stage femtosecond to nanosecond (fs-ns) photodynamics can be challenging. Here we introduce a combined ultrafast transient absorption-spectroelectrochemistry (TA-SEC) approach using freestanding boron doped diamond (BDD) mesh electrodes, which also extends the time domain of conventional spectrochemical measurements. The BDD electrodes offer a wide solvent window, low background currents, and a tuneable mesh size which minimises light scattering from the electrode itself. Importantly, reactive intermediates are generated electrochemically, via oxidation/reduction of the starting stable species, enabling their dynamic interrogation using ultrafast TA-SEC, through which the early stages of the photoinduced relaxation mechanisms are elucidated. As a model system, we investigate the ultrafast spectroscopy of both anthraquinone-2-sulfonate (AQS) and its less stable counterpart, anthrahydroquinone-2-sulfonate (AH(2)QS). This is achieved by generating AH(2)QS in situ from AQS via electrochemical means, whilst simultaneously probing the associated early-stage photoinduced dynamical processes. Using this approach we unravel the relaxation mechanisms occurring in the first 2.5 ns, following absorption of ultraviolet radiation; for AQS as an extension to previous studies, and for the first time for AH(2)QS. AQS relaxation occurs via formation of triplet states, with some of these states interacting with the buffered solution to form a transient species within approximately 600 ps. In contrast, all AH(2)QS undergoes excited-state single proton transfer with the buffered solution, resulting in formation of ground state AHQS(-) within approximately 150 ps.

Artificial light-harvesting systems in aqueous media which mimic nature are of significant importance; however, they are often restrained by the solubility and the undesired aggregation-caused quenching effect of the hydrophobic chromophores. Here, we report a generalized strategy toward the construction of efficient artificial light-harvesting systems based on supramolecular peptide nanotubes in water. By molecularly aligning the hydrophobic chromophores along the nanotubes in a slipped manner, an artificial light-harvesting system with a two-step sequential Förster resonance energy transfer process is successfully fabricated, showing an energy transfer efficiency up to 95% and a remarkably high fluorescence quantum yield of 30%, along with high stability. Furthermore, the spectral emission could be continuously tuned from blue through green to orange, as well as outputted as a white light continuum with a fluorescence quantum yield of 29.9%. Our findings provide a versatile approach of designing efficient artificial light-harvesting systems and constructing highly emissive organic materials in aqueous media.