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Full Article Figures & data References Supplemental Citations Metrics Reprints & Permissions Read this article Abstract The characterization of fabrics after applying different degradation conditions appears to be a key factor to understand their behaviour for different applications. Depending on the treatment, morphologic and polymorphic changes may arise in the polymeric chain structure that composes textile fibers. In this paper, a systematic and comparative study between different types of natural and synthetic textile fabrics was carried out in order to shed light on the structural changes occurring under acid and alkali treatments. The natural fabric polymers studied had a cellulose-based composition from plants (cotton, linen and jute), or a protein-based one from animals (silk and wool). The synthetic fabric was polyester. Different treatment times were assessed: 15 min, 1, 2, 4, 8 and 24 h and compared to the initial condition of the fabrics (standard). In the cellulosic fabrics, the alkali provoked the polymorphic transformation of the amorphous CI into CII. However, the acid treatment did not cause any remarkable alteration in the structure. In protein fabrics, the acid treatment increased the amorphicity of the structures, leading to further degradation but not affecting the conformation of proteins, and the alkali dissolved the fabrics. Polyester was not affected by the chemical solutions (neither acid nor alkali).

Abstract: When clothing is worn multiple times by a consumer, a build-up of oily soils, dirt, odours, and bacteria can transfer from the wearer to the garment. The bacteria that have been transferred to the garment may result in unwanted odours. Over time, this accumulation of bacteria may cause persistent odours that remain in clothing even after laundering. In addition, fibre type may influence how textiles retain and transfer bacteria. The purpose of this in vitro laboratory study was to examine if bacteria can accumulate in apparel fabrics with repeated use/laundering cycles. Three inoculation/wash levels were used (1, 2, 5). Cotton and polyester fabrics were inoculated with Staphylococcus aureus and later laundered. After laundering, bacterial counts from cotton and polyester fabric specimens were calculated in colony forming units (CFU) per sample. Three groups of fabric specimens were used in this study, baseline, treatment, and control. Baseline specimens were used to provide an initial bacterial count of the treatment fabrics to investigate if there was a build-up of bacteria after laundering the treatment specimens. The control fabrics were used to examine the transference of bacteria between fabrics during washing. No differences were found in log CFU per sample of S. aureus on treatment fabrics as the number of inoculation/laundering cycles increased. This suggests that bacteria did not accumulate on either cotton or polyester fabrics as the number of cycles increased. The transfer of bacteria between fabrics during the wash cycle was also examined in this research. It was found that bacteria transferred from the inoculated fabrics to the control fabrics during laundering. The transference of bacteria was minimal for cotton and polyester fabrics. Despite the expectation that bacteria would build-up as the number of inoculation/wash cycles increased, there was no evidence for this in the current study. While laundering can reduce the bacterial counts laundering was not sufficient in removing all S. aureus colonies from both cotton and polyester specimens.

Forensic analysis of evidence consists of the comparison of physical, spectroscopic, or chemical characteristics of a questioned sample to a set of knowns. Currently, decisions as to whether or not the questioned sample can be associated or grouped with the knowns are left up to the discretion of the forensic analyst. The implications of these outcomes are presented as evidence to a jury in a court of law to determine if a defendant is guilty of committing a crime or not. Leading up to, and since, the publication of the National Academy of Sciences (NAS) report entitled “Strengthening Forensic Science in the United States: A Path Forward,” the inadequacies of allowing potentially biased forensic opinion to carry such weight in the courtroom have been unmasked. This report exposed numerous shortcomings in many areas of forensic science, but also made recommendations on how to fortify the discipline. The main suggestions directed towards disciplines that analyze trace evidence include developing error rates for commonly employed practices and evaluating method reliability and validity. This research focuses on developing a statistical method of analysis for comparing visible absorption profiles collected from highly similarly colored textile fibers via microspectrophotometry (MSP). Several chemometric techniques were applied to spectral data and utilized to help discriminate fibers beyond the point where traditional methods of microscopical examination may fail. Because a dye's chemical structure dictates the shape of the absorption profile, two fibers dyed with chemically similar dyes can be very difficult to distinguish from one another using traditional fiber examination techniques. The application of chemometrics to multivariate spectral data may help elicit latent characteristics that may aid in fiber discrimination. The three sample sets analyzed include dyed fabric swatches (three pairs of fabrics were dyed with chemically similar dye pairs), commercially available blue yarns (100% acrylic), and denims fabrics (100% cotton). Custom dyed swatches were each dyed uniformly with a single dye whereas the dye formulation for both the yarns and denims is unknown. As a point for study, spectral comparisons were performed according to the guidelines published by the Standard Working Group for Materials Analysis (SWGMAT) Fiber Subgroup based on visual analysis only. In the next set of tests, principal components analysis (PCA) was utilized to reduce the dimensionality of the large multivariate data sets and to visualize the natural groupings of samples. Comparisons were performed using the resulting PCA scores where group membership of the questioned object was evaluated against the known objects using the score value as the distance metric. Score value is calculated using the score and orthogonal distances, the respective cutoff values based on a quantile percentage, and an optimization parameter, ?. Lastly, likelihood ratios (LR) were generated from density functions modelled from similarity values assessing comparisons between sample population data. R code was written in-house to execute all method of fiber comparisons described here. The SWGMAT method performed with 62.7% accuracy, the optimal accuracy rate for the score value method was 75.9%, and the accuracy rates for swatch-yarn and denim comparisons, respectively, are 97.7% and 67.1% when the LR method was applied.

Spider silk is renowned for its extraordinary mechanical properties, having a balance of high tensile strength and extensibility. To date, the majority of studies have focused on the production of dragline silks from synthetic spider silk gene products. Here we report the first mechanical analysis of synthetic egg case silk fibers spun from the Latrodectus hesperus tubuliform silk proteins, TuSp1 and ECP-2. We provide evidence that recombinant ECP-2 proteins can be spun into fibers that display mechanical properties similar to other synthetic spider silks. We also demonstrate that silks spun from recombinant thioredoxin-TuSp 1 fusion proteins that contain the conserved C-terminal domain exhibit increased extensibility and toughness when compared to the identical fibers spun from fusion proteins lacking the C-terminus. Mechanical analyses reveal that the properties of synthetic tubuliform silks can be modulated by altering the post-spin draw ratios of the fibers . Fibers subject to increased draw ratios showed elevated tensile strength and decreased extensibility, but maintained constant toughness. Wide-angle X-ray diffraction studies indicate that post-drawn fibers containing the Cterminal domain of TuSp 1 have more amorphous content when compared to fibers lacking the C-terminus. Taken together, these studies demonstrate that recombinant tubuliform spidroins that contain the conserved C-terminal domain with embedded protein tags can be effectively spun into fibers, resulting in similar tensile strength but increased extensibility relative to non-tagged recombinant dragline silk proteins spun from equivalently sized proteins.

Spider attachrnentdisc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila c/avipes. MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySpl. PySp2 contains internal block repeats that consist of two sub-repeat units: one dominated by Ser, Gin and Ala, the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich sub-repeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequence with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs.

Trace textile fiber evidence is found at numerous crime scenes and plays an important role in linking a suspect to the respective scene. Several methods currently exist for the analysis of trace fiber evidence. Microscopy provides information regarding the fibers material, color and weave. For more detailed chemical analysis chromatographic methods are employed and for discrimination between dyes, liquid chromatography coupled with mass spectrometry (LC-MS) is currently the method providing the most discrimination. These methods have primarily focused on the dyes used to color the fibers and have not investigated other components that can potentially discriminate among fibers. This dissertation deals with investigations into the fluorescence of the fiber dyes, (contaminants?) and the fibers themselves, as well as methodology for discriminating between fibers using fluorescence. Initial systematic analysis was conducted on dye standards and extracts taken from fibers colored with the respective dyes of interest. Absorbance, excitation and fluorescence spectra were compared between standards and extracts to determine the optimal area of the fiber to investigate: dyes, fluorescent impurities or the whole fiber. High performance liquid chromatography investigations were performed to give detailed information on the number of dye and fluorescent components present in extracts. Our investigations then focused on the best room-temperature fluorescence (RTF) data format for analysis and discrimination of fiber samples. An excitation emission matrix (EEM) was found to give the greatest amount of spectral information and provide the highest level of discrimination. Successful discrimination between non similar and similar fibers was achieved with the aid of Chemometric analysis. The level of discrimination obtained via RTF-EEM spectroscopy was sufficient to differentiate among fibers obtained from two separate cloths of the same material and colored with the same dye reagent. Final studies deal with examining exposure of the fiber to various environmental contaminants. Clothing fibers are typically exposed to myriad numbers of contaminants, from food stains to cigarette smoke. The challenge then becomes detecting fluorescence signals from trace amounts of these environmental contaminants. We demonstrate the detection and classification of polycyclic aromatic hyrdrocarbons (PAH) present on fibers after exposure to cigarette smoke. This dissertation also investigates the change in fluorescence emission after laundering fibers numerous times. The main drawback of chemical analysis of fibers is the destructive nature of the methods. To extract a dye or contaminant from a fiber essentially destroys the evidence. This leaves the investigator without their original sample in the courtroom. This also provides a finite amount of sample for testing and analysis. This is true of chromatographic methods and for the method detailed in this dissertation which makes use of extracts taken from fiber samples. Lastly, we propose an instrumental setup coupling a microscope to a spectrofluorimeter for the purpose of taking EEM directly from a fiber sample. This setup makes use of the superior optics of the microscope for focusing excitation light onto the fiber sample. Initial studies have been performed on extracts from a single textile fiber and EEM collected from said fiber.