Debris Analysis Research Articles

Recovery of oxygenated ignitable liquids by zeolites, Part I: Novel extraction methodology in fire debris analysis

The recovery of low molecular weight oxygenates in fire debris samples is severely compromised by the use of heated passive headspace concentration with an activated charcoal strip, as outlined in ASTM E-1412. The term “oxygenate” is defined herein as a small, polar, organic molecule, such as acetone, methanol, ethanol, or isopropanol, which can be employed as an ignitable liquid and referred to in the ASTM classification scheme as the “oxygenated solvents” class. Although a well accepted technique, the higher affinity of activated carbon strips for heavy molecular weight products over low molecular weight products and hydrocarbons over oxygenated products, it does not allow for efficient recovery of oxygenates such as low molecular weight alcohols and acetone. The objective of this study was to develop and evaluate a novel method for the enhanced recovery of oxygenates from fire debris samples. By optimizing conditions of the heated passive headspace technique, the utilization of zeolites allowed for the successful collection and concentration of oxygenates. The results demonstrated that zeolites increased the recovery of oxygenates by at least 1.5-fold compared to the activated carbon strip and may complement the currently used extraction technique.

Wind turbine condition monitoring

Wind turbine condition monitoring

Analysis of arson fire debris by low temperature dynamic headspace adsorption porous layer open tubular columns

In this paper we present results of the application of PLOT-cryoadsorption (PLOT-cryo) to the analysis of ignitable liquids in fire debris. We tested ignitable liquids, broadly divided into fuels and solvents (although the majority of the results presented here were obtained with gasoline and diesel fuel) on three substrates: Douglas fir, oak plywood and Nylon carpet. We determined that PLOT-cryo allows the analyst to distinguish all of the ignitable liquids tested by use of a very rapid sampling protocol, and performs better (more recovered components, higher efficiency, lower elution solvent volumes) than a conventional purge and trap method. We also tested the effect of latency (the time period between applying the ignitable liquid and ignition), and we tested a variety of sampling times and a variety of PLOT capillary lengths. Reliable results can be obtained with sampling time periods as short as 3min, and on PLOT capillaries as short as 20cm. The variability of separate samples was also assessed, a study made possible by the high throughput nature of the PLOT-cryo method. We also determined that the method performs better than the conventional carbon strip method that is commonly used in fire debris analysis.

Progress Toward the Determination of Correct Classification Rates in Fire Debris Analysis II: Utilizing Soft Independent Modeling of Class Analogy (SIMCA)

A multistep classification scheme was used to detect and classify ignitable liquid residues in fire debris into the classes defined by the ASTM E1618-10 standard method. The total ion spectra (TIS) of the samples were classified by soft independent modeling of class analogy (SIMCA) with cross-validation and tested on fire debris. For detection of ignitable liquid residue, the true-positive rate was 94.2% for cross-validation and 79.1% for fire debris, with false-positive rates of 5.1% and 8.9%, respectively. Evaluation of SIMCA classifications for fire debris relative to a reviewer's examination led to an increase in the true-positive rate to 95.1%; however, the false-positive rate also increased to 15.0%. The correct classification rates for assigning ignitable liquid residues into ASTM E1618-10 classes were generally in the range of 80-90%, with the exception of gasoline samples, which were incorrectly classified as aromatic solvents following evaporative weathering in fire debris.

An adaptive strategy for active debris removal

Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris.One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population.DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net growth for that particular projection after 200years.The results show that using an adaptive ADR rate generated by CASCADE, alongside good compliance with existing mitigation measures, increases the probability of achieving a constant LEO population of objects greater than 10cm. This was shown to be 12% greater compared with removing five objects per year, with the additional advantage of requiring only 3.1 removals per year, on average.

Foot ulcers in diabetes mellitus patients – protein analysis of wound environment

Diabetes mellitus (DM) is associated with many health complications and foot ulcers are one of the escalating, which brings uncomfortable and painful lifestyle for DM patients. In severe cases, foot ulcers can lead to a lower extremity amputation or even death. The treatment of such affected patients results in a high economic load [1]. Immune system of DM patients shows improper function leading to chronic wound of foot ulcers. In a physiological wound healing, wound is cleared from bacteria by immune cells, keratinocytes perform re-epithelization, fibroblasts restore dermis matrix and endothelial cells ensure angiogenesis. All is perfectly driven by growth factors, cytokines and chemokines which are dozen in a sensitive balance. In the foot ulcers of DM patients, immune cells over-express pro-inflammatory cytokines and chemokines (IL-1, IL-6, TNF-α, CCL2, CCL3, CCL4, CXCL1, CXCL5, CXCL8) and are not able to clear wound bed from infection. Fibroblasts and keratinocytes have reduced proliferative, locomotive and secreting functions and are not able to renovate epidermis and dermis followed by lacking angiogenesis [2]. High levels of pro-inflammatory cytokines, chemokines and proteases produced by persisting bacteria and activated immune cells represent main factors supporting the improper healing of foot ulcers. The standard treatment of diabetic ulcers includes optimization of glycemic control, extensive debridement, infection elimination, use of moisture dressings, and offloading high pressure. New approaches such as autologous skins transplantation, mesenchymal stem cell application or dressings containing growth factors started to be utilized [1]. The development of new treatments requires a multidisciplinary cooperation and a deep molecular-biological research. The identification of microbiological contamination is a common approach and serves for the development and the evaluation of efficient antibacterial preparations. The protein analysis of wound debris and wound exudates utilizing multiplex immunological methods represent a quite new method and can provide an overview of chronic wound protein content, which can bring information for the development of curing preparations focused on cytokine, chemokine or proteases function. The determination of protein composition of chronic wound further enables the monitoring of healing process and provides the data about efficacy of healing management. Although the foot ulcers care is at high level and not all patients are judged to extremity amputation, the healing of foot ulcers in DM patients is a constant challenge. The field for development of an effective, economically and patient’s friendly medical preparation with doctor’s favorable application form is still open.

ACTUAL PROCESS PARAMETER DETERMINATION FOR MICRO-ENGRAVING OF FULLERENE FILM

Mechanical engineers are consistently challenged with the requirements posed by contemporary materials machining by using the existing equipment. In this case determining the cutting conditions becomes an actual problem. This paper offers a response to that request in the form of micro-machining of thin fullerene film deposited on a glass plate by using chemical vapor deposition method. Experimental verification of thin fullerene film machinability is conducted on computer numerical control engraving machine using a diamond scraper. Different values of process parameters are combined to determine adequate parameters set from groove edge quality aspect. During machining we noticed intensive wear, so one part of our research was directed towards determining the cause of tool wear. Modern equipment was used for qualitative analysis and near-optimal cutting condition selection and for analysis of wear debris. The results present a basis for further process optimization of thin fullerene film micro-engraving and for introduction of cutting conditions in the existing table for well-known materials.

Investigations on performance of ECDM process using NaOH and NaNO<SUB align="right">3 electrolytes while micro machining soda lime glass

Electro chemical discharge machining (ECDM) is a proven process for micro machining difficult to process non-conductive materials. The experimental results [material removal (MR) and tool wear (TW)], while fabricating shallow holes on soda lime glass using ECDM process; have been reported in the paper. The electrolytes viz. NaOH and NaNO3 were used during the micromachining on soda lime glass. The detailed parametric study was planned using the standard L9 orthogonal array. Influence of process parameters, namely electrolyte concentration, applied voltage, distance between electrodes and time of current flow on response parameter, i.e., MR were analysed. The results showed that NaOH was more efficient as compared to NaNO3. The results on MR showed that all parameters were significant and applied voltage was found to be the most influencing parameter (70.14%). Field emission scanning electron microscopy (FESEM) and debris analysis were further carried out to study the performance of the ECDM process.

917 MSE法を用いた超硬合金の表面強度評価 : 摩耗粉解析による摩耗形態の考察(OS11-5 機械要素とトライボロジー,オーガナイズドセッション11:「機械要素とトライボロジー」)

917 MSE法を用いた超硬合金の表面強度評価 : 摩耗粉解析による摩耗形態の考察(OS11-5 機械要素とトライボロジー,オーガナイズドセッション11:「機械要素とトライボロジー」)

Evaluation of a Headspace Solid‐Phase Microextraction Method for the Analysis of Ignitable Liquids in Fire Debris

The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions--extraction temperature, incubation and exposure time--were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris.

Analysis of wear debris in rolling contact fatigue cracks of pearlitic railway wheels

In the current study a severe subsurface crack network in a railway wheel has been studied and compared to typical rolling contact fatigue cracks found in the wheel tread surface. Microstructural characteristics, chemical composition and microhardness within the cracks and around crack faces were examined. While the two damage types are principally different, both showed similar crack characteristics, with short cracks branching along the main crack paths and a discontinuous sheared layer of wear debris and metallic flakes within them. Analyses of the wear debris showed that it does not originate from external contamination or being the result of corrosion primarily. Instead it has most likely been produced by shear deformation and wear mechanisms within crack faces caused by mixed-mode crack growth. Although microstructural appearance at lower magnification seemed to differ from the bulk material, at high magnification a lamellar structure was observed consisting of layers of deformed metallic flakes and particles of the base metal. Auger electron spectroscopy was used to analyze these sheared layers; higher concentration of oxygen was measured in between flakes, indicating the presence of oxides and flakes being of similar chemical composition as the base material. A possible explanation is that these layers are created due to high shear forces and friction between crack faces in the service of the wheel. With continued rolling the material being sheared by the cyclic relative motion of the crack faces disintegrates into smaller wear debris particles with concurrent oxidation.

Reflection of changes in sea surface circulation over the northeastern Iceland Basin in planktonic foraminiferal assemblages during the late Pleistocene-Holocene

Paleotemperature reconstructions based on foraminiferal analysis and estimates of the iceberg-rafted debris (IRD) obtained from sediment core AMK-4438 are provided. The sediments are dated 300 ka. It was shown that, during this period, sea surface conditions in the northeastern Iceland Basin varied considerably because of both glacial-interglacial alternation and short-term fluctuations of sea surface temperature due to ice melting during the Heinrich events.

The many futures of active debris removal

In the last decade, space debris modelling studies have suggested that the long-term low Earth orbit (LEO) debris population will continue to grow even with the widespread adoption of mitigation measures recommended by the Inter-Agency Space Debris Coordination Committee. More recently, studies have shown that it is possible to prevent the expected growth of debris in LEO with the additional removal of a small number of selected debris objects, through a process of active debris removal (ADR). In order to constrain the many degrees of freedom within these studies, some reasonable assumptions were made concerning parameters describing future launch, explosion, solar and mitigation activities. There remains uncertainty about how the values of these parameters will change in the future. As a result, the effectiveness of ADR has only been established and quantified for a narrow range of possible future cases. There is, therefore, a need to broaden the values of these parameters to investigate further the potential benefits of ADR.A study was completed to model and quantify the influence of four key parameters describing launch and explosion rates, the magnitude of solar activity and the level of post-mission disposal compliance on the effectiveness of ADR to reduce the LEO debris population. Each parameter's value was drawn from a realistic range, based upon historical data of the last 50 years and, in the case of post-mission disposal, a current estimate of the level of compliance and a second optimistic value. Using the University of Southampton's Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) model, the influence of each parameter was modelled in Monte Carlo projections of the ≥5cm LEO debris environment from 2009 to 2209. In addition, two ADR rates were investigated: five and ten removals per year.The results showed an increase in the variance of the size of the LEO population at the 2209 epoch compared with previous ADR modelling studies. In some cases, the number of LEO debris objects in the population varied by a factor greater than ten. Ten removals per year were not sufficient to prevent the long-term growth of the population in some cases, whilst ADR was not required to prevent population growth in others.

Quantitative analysis of plastic debris on recreational beaches in Mumbai, India

Plastic litter was quantified on four sandy beaches in Mumbai. The mean abundance of 7.49g and 68.83 items per square metre was recorded. The abundance of plastics significantly varied among the beaches showing an increasing trend in the southern part. The abundance of plastics by weight in Dadar was significantly higher than that in Aksa. The size fractionation of plastics proved that small particles (1–20mm) are predominant with 41.85% microplastics (1–5mm) which emphasizes the high risk to marine organisms due to possible ingestion. The highest quantity of microplastics was seen in Juhu beach (55.33%) followed by Versova, Aksa and Dadar. The major contributing factors for the abundance are beach usage for different activities such as recreational, religious and fishing which suggest that the land-based sources provide major inputs to plastic pollution in these beaches.

Analysis of household ignitable liquids and their post-combustion weathered residues using compound-specific gas chromatography-combustion-isotope ratio mass spectrometry

The continuing rise in home and vehicular arson cases involving the use of ignitable liquids continues to be an area of concern for criminal and civil investigators. In this study, the compound-specific δ13C values of various components of four flammable household chemicals were measured using a single quadrupole mass spectrometer and an isotope ratio mass spectrometer as simultaneous detectors for a gas chromatograph. Whereas compound-specific carbon isotope ratios were able to discriminate between different sources of neat (pre-combustion) ignitable liquids, analyses of the post-combustion residues were problematic. Weathering caused by combustion resulted in a significant increase in the 13C content of specific peaks relative to the neat liquids (i.e. less negative delta values) such that the isotopic comparison of pre- and post-combustion residues resulted in fractionation ranging from 0 to +10‰. Because of the current lack of understanding of isotopic fractionation during combustion, and because of problems encountered with co-elution in the more complex samples, compound-specific IRMS does not appear to be suitable for fire debris analysis. The comparison of non-combusted or non-weathered ignitable liquids is much more reliable, especially for relatively simple mixtures, and is best suited for exclusionary purposes until such time as a comprehensive database of samples is developed. Without a measure of the population variance, one cannot presently predict the false positive identification rate for the comparison of two ignitable liquids; i.e. the probability that two random ignitable liquid samples have indistinguishable isotope ratios.

Taking it to the River: Arkansas Novaculite Quarrying and Archaic Period Tool Production

Arkansas Novaculite, outcropping on ridge tops in the Ouachita Mountains of Arkansas and Oklahoma, was a critical resource for Indians living in both mountains and coastal plains. We review recent archaeological research on novaculite quarries and the movement of toolstone away from outcrops, especially during the Middle and Late Archaic Period (6,100-650 BC). Toolstone procurement was intensive and extensive, as shown through mapping of quarry features at Spanish Diggings, a major quarry at the southeastern end of the Novaculite Uplift. Analysis of tool production debris at the Jones Mill Site on the Ouachita River focuses on identifying heat treatment and biface reduction as people moved novaculite from source to habitation.

Dynamics Analysis of Debris in the Thin Cavity

The oil condition monitor asks for wear derbies moving into the oil thin cavity stably which is on wear derbies image collecting apparatus, and reduces some phenomena of the wear derbies, such as roll, deposition and self-lock characterization, in order to enhance the quality of wear derbies image. This paper has first studied about the moving video image of the wear particles in an oil thin cavity. A qualitative research on the movement of the wear derbies, such as roll, deposition and self-lock characterization, has been investigated. Then dynamics of wear derbies is analyzed .The paper presents apparatus to avoid the overlap and jam of wear debris on the basic of the result of dynamics analysis. The oil thin cavity is considered to be laid vertically during the experiment.

Dry Sliding Wear Behaviour of Ti–6Al–4V Alloy Consisting of Bimodal Microstructure

In the present paper, dry sliding wear behaviour of Ti–6Al–4V titanium alloy consisting of bimodal microstructure sliding against EN-31 steel at different sliding velocities (0.3, 0.6 and 0.9 m/s) and applied loads (60, 80 and 100 N) has been studied using a multiple Tribo tester and the results are presented. Two wear mechanisms have been identified irrespective of the applied load: oxidative wear occurs at the lowest sliding velocities and delamination wear occurs at the highest. Results indicated that by increasing the sliding velocity a transition from oxidative wear to delamination wear occurs with a corresponding minimum in the loss of volume due to wear. These results have been described by the analysis of the wear debris and that of the worn specimens using XRD, optical microscopy, FESEM and interpreted based on the metallurgical characteristics of titanium alloys which influence the wear resistance.

Large cryoconite aggregates on a Svalbard glacier support a diverse microbial community including ammonia-oxidizing archaea

The aggregation of surface debris particles on melting glaciers into larger units (cryoconite) provides microenvironments for various microorganisms and metabolic processes. Here we investigate the microbial community on the surface of Aldegondabreen, a valley glacier in Svalbard which is supplied with carbon and nutrients from different sources across its surface, including colonies of seabirds. We used a combination of geochemical analysis (of surface debris, ice and meltwater), quantitative polymerase chain reactions (targeting the 16S ribosomal ribonucleic acid and amoA genes), pyrosequencing and multivariate statistical analysis to suggest possible factors driving the ecology of prokaryotic microbes on the surface of Aldegondabreen and their potential role in nitrogen cycling. The combination of high nutrient input with subsidy from the bird colonies, supraglacial meltwater flow and the presence of fine, clay-like particles supports the formation of centimetre-scale cryoconite aggregates in some areas of the glacier surface. We show that a diverse microbial community is present, dominated by the cyanobacteria, Proteobacteria, Bacteroidetes, and Actinobacteria, that are well-known in supraglacial environments. Importantly, ammonia-oxidizing archaea were detected in the aggregates for the first time on an Arctic glacier.

Assessment of epidural versus intradiscal biocompatibility of PEEK implant debris: an in vivo rabbit model

To understand the relative histopathological effects of PEEK particulate debris when applied within the epidural versus the intervertebral disc space. We hypothesized that due to the avascular nature of the intervertebral disc acting as a barrier to immune cells, the intradiscal response would be less than the epidural response. The inflammatory effects of clinically relevant doses (3 mg/5-kg rabbit) and sizes (1.15 µm diameter) of PEEK implant debris were assed when placed dry on epidural and intradiscal tissues in an in vivo rabbit model. The size of the particulate was based on wear particulate analysis of wear debris generated from simulator wear testing of PEEK spinal disc arthroplasty devices. Local and systemic gross histology was evaluated at the 3- and 6-month time points. Quantitative immunohistochemistry of local tissues was used to quantify the common inflammatory mediators TNF-α, IL-1β, and IL-6. Both treatments did not alter the normal appearance of the dura mater and vascular structures; however, limited epidural fibrosis was observed. Epidural challenge of PEEK particles resulted in a significant (30 %) increase (p < 0.007) in TNF-α and IL-1β at both 3 and 6 months compared to that of controls, and IL-6 at 6 months (p < 0.0001). Intradiscal challenge of PEEK particles resulted in a significant increase in IL-1β, IL-6 and TNF-α at 6-months post-challenge (p ≤ 0.03). However, overall there were only moderate increases in the relative amount of these cytokines when compared with surgical controls (10-20 %). In contrast, epidural challenge resulted in a 50-100 % increase. The results of this study are similar to past investigations of PEEK, whose results have not been shown to elicit an aggressive immune response. The degree to which these results will translate to the clinical environment remains to be established, but the pattern of subtle elevations in inflammatory cytokines indicated both a mild persistence of responses to PEEK debris, and that intradiscal implant debris will likely result in less inflammation than epidural implant debris.