729 research outputs found
Recovery of fresh latent fingerprints on black clothing fabrics using Lumicyano™
The importance of fingerprint evidence cannot be underestimated as it can provide valuable information pertaining to perpetrator of a crime. However, there is no recognised method for the enhancement of latent fingerprints on clothing fabrics. As a result, forensic laboratories rarely attempt to recover fingerprints from such substrates. Recently, new cyanoacrylate (CA) products such as Lumicyano™ have been developed. This method incorporates a fluorescent staining dye powder 3-chloro-6-ethoxy-1,2,4,5-tetrazine (C₄H₅ClN₄O) and liquid ethyl CA into a solution. Therefore, Lumicyano™ can develop fluorescent fingerprints in a one-stage fuming process without the need for an additional visualisation method apart from Forensic Light Source (FLS). The integration of fluorescent dye and CA into a mixture suggests that the fluorescent dye would selectively adhere to the polycyanoacrylate formed on the friction ridges of fingerprints. The readily visible fingerprints and the removal of the post-processing method indicate that Lumicyano™ could potentially be used on fabrics. Thus, this preliminary study aimed at assessing the efficacy of Lumicyano™ on recovering fresh latent fingerprints on black clothing fabrics. This was achieved by developing fresh latent fingerprints deposited on four different types of black clothing fabric materials; polyester, cotton, poly cotton, and nylon. The results showed that Lumicyano™ is an effective method to develop fresh latent fingerprints on black clothing fabrics. Furthermore, an indirect comparison between Lumicyano™ and silver VMD results obtained from another study was performed. The results suggest that Lumicyano™ is a better enhancement method to enhance fingerprints on black polyester and poly cotton fabrics than silver VMD. The fibre material, thread count, weave pattern of the clothing fabrics, and the fingerprint donor were proven to be important in determining the quality of the developed prints.
Keywords: Forensic science, Fingerprint evidence, Lumicyano™, Fabric
3D TEXTILE PREFORMS AND COMPOSITES FOR AIRCRAFT STRCUTURES: A REVIEW
Over the last decades, the development of 3D textile composites has been driven the structures developed to overcome disadvantages of 2D laminates such as the needs of reducing fabrication cost, increasing through-thickness mechanical properties, and improving impact damage tolerance. 3D woven, stitched, knitted and braided preforms have been used as composites reinforcement for these types of composites. In this paper, advantages and disadvantages of each of them have been comprehensively discussed. The fabric architects and their specification in particular stitched preforms and their deformation mode for aerospace applications have been reviewed. Exact insight into various types of damage in textile preforms and composite that have the potential to adversely affect the performance of composite structure along with their inspection using NDT techniques have been elaborated. The research review reported in this paper can be very valuable to researchers to release the 3D composite behaviour under different loading conditions and also to get familiar with the manufacture of high quality textile composite for aircraft structures
An investigation into the feasibility of the integration of microwave circuitry into a woven textile
To investigate the integration of a textile antenna into a woven substrate at the point of production. The antenna was to have the characteristics of a conventional fabric interms of the handle and drape
New fortuitous materials for luminescence dosimetry following radiological emergencies
The effective management of radiological emergencies where members of the public not carrying conventional dosimeter have been exposed to doses of ionising radiation requires individual dose estimates to support medical triage. Biological and physical methods have been developed to address this issue. New materials and techniques have been sought to reinforce preparedness for such emergencies. Alternative materials, such as clothing, shoes, paper, plastic items, nail polish or banknotes were investigated using thermoluminescence (TL) and optically stimulated luminescence (OSL).
Most of the materials and fabric tested exhibited either no detectable response to dose using luminescence technique, or a weak response yielding detection limits above 2 Gy, with the exceptions of a blue polyester fabric responding to infra-red stimulated luminescence (IRSL) and some types of polymer-based fabric that were found to have luminescence favourable characteristics for short - term dosimetry and particularly those containing mineral fillers.
The most promising were fabrics containing calcium carbonate fillers, where the TL response to β radiations was measured with a detection limit as low as 4 mGy, and a relatively low native signal in the region of interest (≤ 200 °C). The fading was found to be slower for samples stored at -15 °C compared with samples stored at ambient temperature. A blind test was carried out and confirmed the potential of bags containing calcium carbonate fillers to provide reliable dose estimate for radiological triage. Furthermore, the TL signal of calcium carbonate fillers contained in the fabric of bags offers several advantages for accident dosimetry compared with other methods, such as a rapid dose assessment, the low cost value of the material and availability, and the possibility to map radiological doses is the fabric covers sufficient surface
Light-Emitting Woven Fabric for Treatment with Photodynamic Therapy and Monitoring of Actinic Keratosis
A successful photodynamic therapy (PDT) requires a specific photosensitizer, oxygen and light of a specific wavelength and power. Today photodynamic therapy (PDT) is administered to patients with light-emitting diode (LED) panels. These panels deliver a non-uniform light distribution on the human body parts, as the complex human anatomy is not a flat surface (head vertex, hand, shoulder, etc.). For an efficient photodynamic therapy (PDT), a light-emitting fabric (LEF) was woven from plastic optical fibers (POF) aiming at the treatment of dermatologic diseases such as actinic keratosis (AK). Plastic optical fibers (POF) (Toray, PGR-FB250) have been woven in textile in order to create macro-bendings, and thus emit out the injected light directly to the skin. The light intensity and light-emitting homogeneity of the LEF were improved thanks to Doehlert Experimental Design. During the treatment with PDT, the photosensitizers were activated in the cancerous cells. These cells may be visualized, as they show a characteristic fluorescence under UV light, which is called fluorescence diagnosis (FD). Therefore, it is proposed to modify the developed LEF for PDT to measure the fluorescence amount. For this aim, a part of POFs was cut out to observe the quantity of light that could be collected while the LEF was connected to a light source. The first prototypes showed the possibility of the illumination with the same LEF without losing the efficiency but also imaging the collected light
Evaluating the Validity and Reliability of Textile and Paper Fracture Characteristics in Forensic Comparative Analysis
In a comparative forensic analysis, an examiner can report that a physical fit exists between two torn or separated items when they realign in a manner unlikely to be replicated. Due to the common belief that it is unlikely that two unrelated fractured objects would match with distinctive characteristics, a physical fit represents the highest degree of association between two items. Nonetheless, despite the probative value that this evidence could have to a trier of fact, few studies have demonstrated such assumptions\u27 scientific validity and reliability. Moreover, there is a lack of consensus-based standard protocols for physical fit comparisons, making it difficult to demonstrate the basis for the features that constitute a “fit.” Since these analyses rely entirely on human judgment, they are highly subjective, which could be problematic in the absence of harmonized examination and interpretation criteria protocols.
As a result, organizations like the National Institute of Justice and NIST-OSAC have identified the need for developing standardized methods and assessing potential error sources in this field. This research aims to address these gaps as applied to physical fits of textiles and paper. Here, standard criteria and prominent features for each material are defined to conduct physical fit examinations in a more reproducible manner. Additionally, a quantitative metric is used to quantify what constitutes a physical fit when conducting comparative analyses of textiles and paper, further increasing the validity and reliability of this methodology and providing a manner of assessing the weight of this evidence when presented in the courtroom.
The first aim of this research involved the development of an objective and systematic method of quantifying the similarity between fractured textile samples. This was done by identifying relevant macroscopic and microscopic characteristics in the comparative analysis of a fractured textile dataset. Additionally, factors that affect the suitability of certain types of textiles for physical fit analysis were evaluated. Finally, the systematic score metric was implemented to quantify and document the quality of a physical fit and estimate error rates.
The second objective of this study consisted of establishing the scientific foundations of individuality concerning the orientation of microfibers in fractured paper edges. In comparative analysis of paper, it is assumed that the microfibers deposited across the surface of paper are randomly oriented, a key feature for addressing the individuality of paper physical fits. However, this hypothesis has not been tested. This research evaluated the rarity and occurrence of microfiber alignments on fractured documents. It also quantified the comparative features of scissor-cut and hand-torn paper and the respective performance rates.
Finally, the comparative analysis of textile and paper physical fits was validated through ground truth datasets and inter-examiner and intra-examiner variability studies. A ground truth blind dataset of known fits and known non-fits was created for 700 textile samples with various fiber types, weave patterns, and separation methods. Also, a set of 260 paper items, including 100 stamps and 160 office paper samples, were examined. The paper specimens contained handwritten or printed entries on two paper types and were separated by scissor-cut or hand-torn methods.
This proposed research provides the criminal justice system with a valuable body of knowledge and a more objective and methodical assessment of the evidential value of physical fits of textiles, paper, and postage stamps
Investigation of 3-D fabrication of ablative materials Final report, 8 Sep. 1965 - 18 Oct. 1966
Textile processes evaluated for fabrication of three-dimensionally reinforced ablative materials - thermal, physical, and mechanical properties of fabric composites with epoxy resi
Optical excitation thermography for twill / plain weaves and stitched fabric dry carbon fibre preform inspection
Carbon fibres have become the natural choice as reinforcements for polymer composite materials (PMCs). The non-destructive inspection of dry carbon fibre preforms has the potential to increase the reproducibility and reduce the cost of PMC manufacturing, by identifying defects in dry multilayer preforms prior to resin injection. However, use of optical excitation thermography for inspecting dry carbon fibre preforms that constitute the structural reinforcement precursor in the manufacturing of PMCs is poorly documented in the open literature. In this work, optical excitation thermography was used for inspecting six dry multilayer carbon fibre preforms featuring different textile structures, thicknesses and defects, for the first time. Advanced image processing techniques were used in processing the thermographic data for comparative purposes. In particular, partial least square thermography, as a recently proposed technique, was studied in detail. Finally, the performance of different thermography techniques was analysed in terms of: 1) summarizing the capabilities of image diagnosis/processing techniques by signal-to-noise ratio analysis, and 2) identifying the monitoring modalities most suitable to industrial manufacturing
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