Post-mortem computed tomography in forensic shooting distance estimation: a porcine cadaver study

Objectives Gunshot wounds are frequently studied using computed tomography (CT) to examine tissue damage. In this study, we aimed to test the potential of post-mortem CT (PMCT) in shooting distance estimation at distances 0–100 cm. We hypothesized that in addition to the wound channel, we could also potentially detect tissue damage caused by muzzle pressure on PMCT. Results A total of 59 gunshot wounds (23 contact shots, 21 close-range shots, 15 distant shots) were inflicted on eight piglet carcasses with a .22 Long Rifle handgun. PMCT scans were obtained using clinical equipment, and they were evaluated for wound characteristics by visual inspection and numeric measurements. In our data, contact shots could be clearly distinguished from close-range and distant shots by a hyperdense ring-shaped area surrounding the outermost part of the wound channel. Close-range and distant shot wounds did not have this feature and were difficult to distinguish from each other. The mean wound channel diameter ranged from 3.4 to 5.4 mm, being smallest in contact shots and largest in distant shots. These preliminary findings suggest that PMCT may aid the estimation of shooting distance. As this study only addressed low velocity gunshot wounds in carcasses, further studies are warranted.Peer reviewe

Post-mortem computed tomography in forensic shooting distance estimation: a porcine cadaver study

Objectives Gunshot wounds are frequently studied using computed tomography (CT) to examine tissue damage. In this study, we aimed to test the potential of post-mortem CT (PMCT) in shooting distance estimation at distances 0–100 cm. We hypothesized that in addition to the wound channel, we could also potentially detect tissue damage caused by muzzle pressure on PMCT. Results A total of 59 gunshot wounds (23 contact shots, 21 close-range shots, 15 distant shots) were inflicted on eight piglet carcasses with a .22 Long Rifle handgun. PMCT scans were obtained using clinical equipment, and they were evaluated for wound characteristics by visual inspection and numeric measurements. In our data, contact shots could be clearly distinguished from close-range and distant shots by a hyperdense ring-shaped area surrounding the outermost part of the wound channel. Close-range and distant shot wounds did not have this feature and were difficult to distinguish from each other. The mean wound channel diameter ranged from 3.4 to 5.4 mm, being smallest in contact shots and largest in distant shots. These preliminary findings suggest that PMCT may aid the estimation of shooting distance. As this study only addressed low velocity gunshot wounds in carcasses, further studies are warranted.Peer reviewe

Intensity of artefacts in cone beam CT examinations caused by titanium and glass fibre-reinforced composite implants

Objectives:The aim was to compare titanium and glass fibre-reinforced composite (FRC) orbital floor implants using cone beam CT (CBCT). FRC implants are nonmetallic and these implants have not been analysed in CBCT images before. The purpose of this study is to compare the artefact formation of the titanium and the FRC orbital floor implants in CBCT images.Methods:One commercially pure titanium and one S-glass FRC with bioactive glass particles implant were imaged with CBCT using the same imaging values (80 kV, 1 mA, FOV 60 × 60 mm). CBCT images were analysed in axial slices from three areas to determine the magnitude of the artefacts in the vicinity of the implants. Quantified results based on the gray values of images were analysed using analysis-of-variance.Results:Compared to the reference the gray values of the titanium implant are more negative in every region of interest in all slices (p Conclusions:The titanium implant caused artefacts in all of the analysed CBCT slices. Compared to the reference the gray values of the FRC implant changed only slightly and this feature enables to use wider imaging options postoperatively

Simple 3D printed stainless steel microreactors for online mass spectrometric analysis

A simple flow chemistry microreactor with an electrospray ionization tip for real time mass spectrometric reaction monitoring is introduced. The microreactor was fabricated by a laser-based additive manufacturing technique from acid-resistant stainless steel 316L. The functionality of the microreactor was investigated by using an inverse electron demand Diels-Alder and subsequent retro Diels-Alder reaction for testing. Challenges and problems encountered are discussed and improvements proposed. Adsorption of reagents to the rough stainless steel channel walls, short length of the reaction channel, and making a proper ESI tip present challenges, but the microreactor is potentially useful as a disposable device.Peer reviewe

Practical realization of a sub-λ/2 acoustic jet

Studies in optics and acoustics have employed metamaterial lenses to achieve sub-wavelength localization, e.g. a recently introduced concept called 'acoustojet' which in simulations localizes acoustic energy to a spot smaller than lambda/2. However previous experimental results on the acoustojet have barely reached lambda/2-wide localization. Here we show, by simulations and experiments, that a sub-lambda/2 wide localization can be achieved by translating the concept of a photonic jet into the acoustic realm. We performed nano-to macroscale molecular dynamics (MD) and finite element method (FEM) simulations as well as macroscale experiments. We demonstrated that by choosing a suitable size cylindrical lens, and by selecting the speed-of-sound ratio between the lens material(s) and the surrounding medium, an acoustic jet ('acoustic sheet') is formed with a full width at half maximum (FWHM) less than lambda/2. The results show, that the acoustojet approach can be experimentally realized with easy-to-manufacture acoustic lenses at the macroscale. MD simulations demonstrate that the concept can be extended to coherent phonons at nanoscale. Finally, our FEM simulations identify some micrometer size structures that could be realized in practice. Our results may contribute to starting a new era of super resolution acoustic imaging: We foresee that jet generating constructs can be readily manufactured, since suitable material combinations can be found from nanoscale to macroscale. Tight focusing of mechanical energy is highly desirable in e.g. electronics, materials science, medicine, biosciences, and energy harvesting.Peer reviewe

Suositus potilaan suojaamisesta röntgentutkimuksissa

Ulkoisia säteilysuojaimia on perinteisesti käytetty ionisoivaa säteilyä hyödyntävässä kuvantamisessa potilaan säteilyherkkien kudosten, elimien ja sikiön suojaamiseksi. Kuvantamistekniikoiden kehittymisen myötä säteilysuojainten käytön tarve on vähentynyt. Tieteellisten tutkimusten myötä myös tieto kudosten ja elimien säteilyherkkyyksistä on parantunut [1]. Terveydenhuollon yksiköissä säteilysuojainten käytön tulee perustua ajankohtaisiin tieteellisiin tutkimustuloksiin ja niiden perusteella laadittuihin suosituksiin. Tämä suositus pohjautuu vuonna 2022 julkaistuun eurooppalaiseen konsensukseen potilaiden suojaamisesta röntgentutkimuksissa [1] sekä muihin tieteellisiin julkaisuihin. Suosituksissa ei oteta kantaa henkilökunnan tai tukihenkilöiden säteilysuojaukseen

Quantifying the Role of Transport by Acoustic Streaming in MHz Focused-Ultrasound-Based Surface Sampling

We have developed an ultrasound-based surface sampling method permitting surface studies for liquid immersed samples. The method employs high-intensity focused ultrasound, which can remove material from predetermined areas and induce acoustic streaming that causes the immersion liquid to flow. In this study, we studied several conditions of acoustic streaming, which can affect particle transport away from the sampled surface. First, we explored suitable acoustic streaming conditions by finite element modelling. Next, we measured the induced streaming fields by particle image velocimetry. This study comprised cases, when a high-intensity focused ultrasound beam encountered a solid surface at different transducer-surface distances. A change in direction of streaming occurred when a focusing transducer was moved from −2λ defocus to -4λ defocus (towards the surface). Thus, we found suitable conditions for an upwards directing acoustic streaming field. This kind of defocus condition can be coupled to the surface sampling process allowing efficient particle transport for subsequent chemical analysis.Peer reviewe

Machining of Aluminium with MHz High-Intensity Focused Ultrasound

Cavitation-induced surface erosion has been studied for decades. High-intensity focused ultrasound (HIFU) enables localized erosion, with applications in many fields. However, no research has been published on machining solely with HIFU. Compared to existing micro-machining technologies, HIFU exhibits a unique set of benefits: inexpensive, minimal maintenance due to non-contact machining without slurry, mitigated chemical load, and monitoring capability. We demonstrate controlled surface machining of mirror-polished aluminium (AW-5754) using high-frequency (12 MHz) HIFU-induced cavitation erosion. Optimal sonication parameters (transducer-sample distance, amplitude, cycles per burst, number of bursts, and pulse repetition frequency) for stationary surface erosion were first identified experimentally. These parameters served as a basis for studying the effect of sonication parameters during on-the-fly erosion, i.e., engraving lines. The effect of stage translation velocity and the number of repeated passes across the engraved line were also studied. Subsequently, the acronym of our laboratory, “ETLA”, was engraved, with a 500 µm letter height and an average line width of 53 µm.Peer reviewe

Identifying Regions-of-Interest and Extracting Gold from PCBs Using MHz HIFU

Increased digitalization and technological development raises the demand for rare and precious metals (RPM). Due to their rarity, mining RPMs from the earth is becoming increasingly difficult. Traditional urban mining methods to recover RPMs from printed circuit boards (PCB) need to separate the RPMs from non-metallic substances, e.g. plastic. This separation requires toxic substances and causes unwanted and toxic by-products and emissions. The ability to identify regions-of-interest on PCBs, i.e. the gold pads, and to extract RPMs from only the desired areas would reduce the need for toxic substances. In this study, a single 12 MHz high-intensity focused-ultrasound transducer was used to 1) image a PCB to locate the gold pads, and 2) to subsequently induce inertial cavitation to remove gold from three extraction areas on the selected gold pad. The sonication was performed in water without additional chemicals. Gold removal was verified by imaging the pad with a coded-excitation scanning acoustic microscope (fc = 375 MHz). Average areas and volumes of the three extraction regions were A = (12.2 ± 0.5)·103 μm2 and V = (18 ± 2)·103 μm3, respectively. The total amount of removed gold and nickel (from beneath the gold plating) from all three extraction areas was estimated to mAu,tot = (570 ± 20) ng and mNi,tot = (440 ± 30) ng. This study constitutes a first step towards more environmentally friendly, non-toxic urban mining of RPMs.Peer reviewe

Chemical analysis using 3D printed glass microfluidics

Additive manufacturing (3D printing) is a disruptive technology that is changing production systems globally. In addition, microfluidic devices are increasingly being used for chemical analysis and continuous production of chemicals. Printing of materials such as polymers and metals is already a reality, but additive manufacturing of glass for microfluidic systems has received minor attention. We characterize microfluidic devices (channel cross-section dimensions down to a scale of 100 mm) that have been produced by additive manufacturing of molten soda-lime glass in tens of minutes and report their mass spectrometric and Raman spectroscopic analysis examples. The functionality of a microfluidic glass microreactor is shown with online mass spectrometric analysis of linezolid synthesis. Additionally, the performance of a direct infusion device is demonstrated by mass spectrometric analysis of drugs. Finally, the excellent optical quality of the glass structures is demonstrated with in-line Raman spectroscopic measurements. Our results promise a bright future for additively manufactured glass microdevices in diverse fields of science.Peer reviewe