@article{li_li_michielsen_2017, title={Effect of yarn structure on wicking and its impact on bloodstain pattern analysis (BPA) on woven cotton fabrics}, volume={276}, ISSN={["1872-6283"]}, DOI={10.1016/j.forsciint.2017.04.011}, abstractNote={Bloodstain pattern analysis (BPA) of bloodstains on hard, non-porous surfaces has found widespread use in crime scene analysis and reconstruction for violent crimes in which bloodshed occurs. At many violent crime scenes, bloody clothing is also found and may be analyzed. However, to date, there are no definitive methods for analyzing bloodstains on textiles, even for simple drip stains. There are two major classes of textiles used for apparel and household textiles, weaves and knits. In this article, drip stains on two 100% cotton plain weave fabrics representative of bed sheets are analyzed. Since it is common practice in the manufacture of bed sheeting to use different types of yarn in the warp and weft direction to reduce cost, custom weaves were made from yarns produced by each of the three most common staple yarn production techniques to control this variable. It was found that porcine blood wicked into the fabrics made with ring spun yarn, but not into those made with open end or vortex spun yarns. The uneven wicking of blood into the different yarns resulted in elliptical-shaped stains on commercial bed sheeting that can be misleading when performing bloodstain pattern interpretation based on the stain morphology. This surprising result demonstrates that it is not sufficient to analyze the structure of the fabric, but one must also characterize the yarns from which the fabric is made. This study highlights the importance of a deeper characterization of the textile structure, even down to the yarn level, for BPA on textiles.}, journal={FORENSIC SCIENCE INTERNATIONAL}, publisher={Elsevier BV}, author={Li, Xingyu and Li, Jingyao and Michielsen, Stephen}, year={2017}, month={Jul}, pages={41–50} }
 @article{li_li_michielsen_2016, title={Alternative method for determining the original drop volume of bloodstains on knit fabrics}, volume={263}, ISSN={["1872-6283"]}, DOI={10.1016/j.forsciint.2016.04.018}, abstractNote={Bloodstains are often observed at violent crime scenes and on the skin and clothing of persons involved. The diameters of the blood drops that created these stains are related to the force or energy that caused these drops to become airborne. This has resulted in several attempts to determine the diameter of the original drops, beginning with the methods reported in the pioneering work of Henry Lee [6]. However, his methods destroyed the bloodstain during the measurement. Other methods described in the literature cannot be applied to bloodstains on textiles. A new, rapid, reliable, non-destructive method for determining the diameter of the original drop of blood that results in a stain has been developed for bloodstains on cotton single jersey knit (tee-shirt) fabrics, which is one of the most common fabrics analyzed for BPA both at crime scenes and in forensic laboratories. In this method, a drop of known volume of an appropriate artificial blood substitute is applied to a region similar to the stained region but in an area away from any stains/areas of interest. The areas of the original stain and the artificial blood substitute stain are determined, from which the original drop diameter can be calculated. Errors in the drop diameters, the Reynolds numbers and the Weber numbers resulting from this procedure are less than approximately 6%. This procedure has only been verified on cotton single jersey knit fabrics with 30μL≤drop volume≤80μL. It should not be applied to other materials.}, journal={FORENSIC SCIENCE INTERNATIONAL}, publisher={Elsevier BV}, author={Li, Jingyao and Li, Xingyu and Michielsen, Stephen}, year={2016}, month={Jun}, pages={194–203} }
 @article{williams_dodds_taylor_li_michielsen_2016, title={Impact dynamics of porcine drip bloodstains on fabrics}, volume={262}, ISSN={["1872-6283"]}, DOI={10.1016/j.forsciint.2016.02.037}, abstractNote={As a passive blood drop impacts a hard surface, it is observed to collapse and spread laterally, then retract and settle. During the spreading phase, the edge of the drop may rise forming a crown extending into spines and breaking up into secondary drops. When a similar drop falls onto a textile surface these same processes may occur, but the process of blood wicking into the fabric complicates stain formation. These processes are described within for passive drip stains collected under controlled conditions using anticoagulated porcine blood. Three stages of this impact process were identified and could be separated into distinct time zones: (1) spreading (time t ≤ 2.5 ms) and (2) retraction (2.5 ≤ t ≤ 12 ms) on the surface with potential splashing at the periphery, and (3) wicking (30 ms ≤ t ≤ 30 min) of the blood into the fabric. Although wetting and wicking may also occur for t < 30 ms, the vast majority of wetting and wicking occur after this time and thus the short-time wicking can be ignored. In addition, the number of satellite stains correlates with the surface roughness with the number of satellites for jersey knit > plain-woven > cardboard. Conversely, the size of the satellite stains correlates with the amount of wicking in the fabric with the satellite stain size for plain-woven > jersey knit > cardboard.}, journal={FORENSIC SCIENCE INTERNATIONAL}, publisher={Elsevier BV}, author={Williams, Elisabeth M. P. and Dodds, Margaret and Taylor, Michael C. and Li, Jingyao and Michielsen, Stephen}, year={2016}, month={May}, pages={66–72} }