Priority pollutants polycyclic aromatic hydrocarbons (PAHs) in muscle and livers of stranded green sea turtles, Chelonia mydas (Linnaeus, 1778) were extracted using a quick, easy, cheap, effective, ...rugged and safe method followed by Gas chromatography/mass spectrometry (GC/MS). Changes to the nature of the extracting solvents, the reaction conditions and the number of co-extractives in the extraction procedure was established to account for the variability of the tissue samples' matrix effect and condition code of each turtle examined. The analytical performance was assessed taking into consideration the analytical recoveries at different fortification levels, matrix effect and instrumental parameters such as selectivity, linearity, and the limits of detection and quantification. Recoveries between 72 and 162% were obtained for most PAHs in liver and 24-107% in muscle samples. Matrix effects assessments showed medium matrix effect, while LOD was on average 0.04 µg g
−1
and LOQ was on average 0.13 µg g
−1
. The extraction showed the best recoveries when extracted using acetonitrile at cold temperature conditions of around 4 °C. Validation results through PCA and correlation analyses showed the suitability of this method for simultaneous determination and confirmation of PAHs in both liver and muscle of stranded turtles at different decomposition levels, matrix complexities and specimen sizes.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Purpose:
To investigate tight-frame based iterative reconstruction (TFIR) technique for spectral breast computed tomography (CT) using fewer projections while achieving greater image quality.
...Methods:
The experimental data were acquired with a fan-beam breast CT system based on a cadmium zinc telluride photon-counting detector. The images were reconstructed with a varying number of projections using the TFIR and filtered backprojection (FBP) techniques. The image quality between these two techniques was evaluated. The image's spatial resolution was evaluated using a high-resolution phantom, and the contrast to noise ratio (CNR) was evaluated using a postmortem breast sample. The postmortem breast samples were decomposed into water, lipid, and protein contents based on images reconstructed from TFIR with 204 projections and FBP with 614 projections. The volumetric fractions of water, lipid, and protein from the image-based measurements in both TFIR and FBP were compared to the chemical analysis.
Results:
The spatial resolution and CNR were comparable for the images reconstructed by TFIR with 204 projections and FBP with 614 projections. Both reconstruction techniques provided accurate quantification of water, lipid, and protein composition of the breast tissue when compared with data from the reference standard chemical analysis.
Conclusions:
Accurate breast tissue decomposition can be done with three fold fewer projection images by the TFIR technique without any reduction in image spatial resolution and CNR. This can result in a two-third reduction of the patient dose in a multislit and multislice spiral CT system in addition to the reduced scanning time in this system.
The estimation of post-mortem interval (PMI) is of critical importance in forensic investigations. This requires thorough knowledge of the decomposition process, with decomposition of remains in ...terrestrial environments extensively investigated, and aquatic environments largely neglected. In terrestrial environments, entomology is well established as a method of PMI estimation, however in an aquatic environment there are no known predictable necrophages, limiting the use of insects. Common to decomposing aquatic remains, algae may serve as a useful alternative to insects for PMI estimation. This pilot study aimed to examine the use of algae for PMI estimation for remains in confined water bodies, and compare this with the practicality of utilizing entomology in aquatic situations. Pigs were either tethered to cement bricks or allowed to float in individual tubs of fresh water for a period of 1000 accumulated degree days (ADD), with algal species seen to bloom on the piglets successively throughout the trials. Insect appearance was inconsistent across replicates throughout decomposition, potentially as a consequence of seasonality. Overall, entomology was proven an unreliable method in aquatic situations. Algal succession may hold promise as a PMI estimation method in confined water bodies, but requires further investigation and evaluation.
Abstract The process of decomposition of bodies in the marine environment is poorly understood and almost nothing is currently known about the microorganisms involved. This study aimed to investigate ...the microbes involved in decomposition in the sea and to evaluate the potential use of marine bacterial succession for postmortem submersion interval (PMSI) estimation, for which there is currently no reliable method. Partial pig remains were completely submerged during autumn and winter and were regularly sampled to document marine bacterial colonisation and the changes in community composition over time. Five stages of decomposition were recognised, some of which exhibited characters specific for partial carrion. Marine bacteria rapidly colonised the submerged remains in a successional manner. Seasonal differences were observed for the rate of decomposition and also for several groups of colonising bacteria. Marine bacteria specific for particular PMSIs were identified. This study provides an insight into the involvement of saprophytic marine bacteria in the decomposition of mammalian remains in the sea and is the first to explore the use of marine bacterial colonisation and succession as a novel tool for PMSI estimation. We propose that with further study, marine bacterial succession will prove useful for determination of the length of time a body may have been immersed in a marine environment.
In digital pathology, devising effective image representations is crucial to design robust automated diagnosis systems. To this end, many studies have proposed to develop object-based ...representations, instead of directly using image pixels, since a histopathological image may contain a considerable amount of noise typically at the pixel-level. These previous studies mostly employ color information to define their objects, which approximately represent histological tissue components in an image, and then use the spatial distribution of these objects for image representation and classification. Thus, object definition has a direct effect on the way of representing the image, which in turn affects classification accuracies. In this paper, our aim is to design a classification system for histopathological images. Towards this end, we present a new model for effective representation of these images that will be used by the classification system. The contributions of this model are twofold. First, it introduces a new two-tier tissue decomposition method for defining a set of multityped objects in an image. Different than the previous studies, these objects are defined combining texture, shape, and size information and they may correspond to individual histological tissue components as well as local tissue subregions of different characteristics. As its second contribution, it defines a new metric, which we call dominant blob scale, to characterize the shape and size of an object with a single scalar value. Our experiments on colon tissue images reveal that this new object definition and characterization provides distinguishing representation of normal and cancerous histopathological images, which is effective to obtain more accurate classification results compared to its counterparts.
Quantitative material decomposition of multiple mixed, or spatially coincident, contrast agent (gadolinium and iodine) and tissue (calcium and water) compositions is demonstrated using ...photon-counting spectral computed tomography (CT). Material decomposition is performed using constrained maximum likelihood estimation (MLE) in the image domain. MLE is calibrated by multiple linear regression of all pure material compositions, which exhibits a strong correlation (
) between the measured x-ray attenuation in each photon energy bin and known concentrations in the calibration phantom. Material decomposition of mixed compositions in the sample phantom provides color material concentration maps that clearly identify and differentiate each material. The measured area under the receiver operating characteristic curve is
, indicating highly accurate material identification. Material decomposition also provides accurate quantitative estimates of material concentrations in mixed compositions with a root-mean-squared error
of the maximum concentration for each material. Thus, photon-counting spectral CT enables quantitative molecular imaging of multiple spatially coincident contrast agent (gadolinium and iodine) and tissue (calcium and water) compositions, which is not possible with current clinical molecular imaging modalities, such as nuclear imaging and magnetic resonance imaging.
The ability to probe fresh tissue is a key feature to biomedical Raman spectroscopy. However, it is unclear how Raman spectra of calcified tissues are affected by freezing. In this study, six ...transverse sections of femoral cortical bone were subjected to multiple freeze/thaw cycles and probed using a custom Raman microscope. Significant decreases were observed in the amide I and amide III bands starting after two freeze thaw cycles. Raman band intensities arising from proline residues of frozen tissue appeared consistent with fresh tissue after four cycles. Crystallinity values of bone mineral diminished slightly with freezing and were noticeable after only one freezing. Mineral carbonate levels did not deviate significantly with freezing and thawing. The authors recommend freezing and thawing bone tissue only once to maintain accurate results.
Purpose:
To investigate the feasibility of an accurate measurement of water, lipid, and protein composition of breast tissue using a photon‐counting spectral computed tomography (CT) with spectral ...distortion corrections.
Methods:
Thirty‐eight postmortem breasts were imaged with a cadmium‐zinc‐telluride‐based photon‐counting spectral CT system at 100 kV. The energy‐resolving capability of the photon‐counting detector was used to separate photons into low and high energy bins with a splitting energy of 42 keV. The estimated mean glandular dose for each breast ranged from 1.8 to 2.2 mGy. Two spectral distortion correction techniques were implemented, respectively, on the raw images to correct the nonlinear detector response due to pulse pileup and charge‐sharing artifacts. Dual energy decomposition was then used to characterize each breast in terms of water, lipid, and protein content. In the meantime, the breasts were chemically decomposed into their respective water, lipid, and protein components to provide a gold standard for comparison with dual energy decomposition results.
Results:
The accuracy of the tissue compositional measurement with spectral CT was determined by comparing to the reference standard from chemical analysis. The averaged root‐mean‐square error in percentage composition was reduced from 15.5% to 2.8% after spectral distortion corrections.
Conclusions:
The results indicate that spectral CT can be used to quantify the water, lipid, and protein content in breast tissue. The accuracy of the compositional analysis depends on the applied spectral distortion correction technique.
: This study examines underwater soft tissue decomposition of dismembered pig limbs deposited in polyethylene plastic bags. The research evaluates the level of influence that disposal method has on ...underwater decomposition processes and details observations specific to this scenario. To our knowledge, no other study has yet investigated decomposing, dismembered, and enclosed remains in water environments. The total sample size consisted of 120 dismembered pig limbs, divided into a subsample of 30 pig limbs per recovery period (34 and 71 days) for each treatment. The two treatments simulated non‐enclosed and plastic enclosed disposal methods in a water context. The remains were completely submerged in Lake Ontario for 34 and 71 days. In both recovery periods, the non‐enclosed samples lost soft tissue to a significantly greater extent than their plastic enclosed counterparts. Disposal of remains in plastic bags therefore results in preservation, most likely caused by bacterial inhibition and reduced oxygen levels.
A controlled laboratory experiment is described, in principle and practice, which can be used for the of determination the rate of tissue decomposition in soil. By way of example, an experiment was ...conducted to determine the effect of temperature (12 degrees, 22 degrees C) on the aerobic decomposition of skeletal muscle tissue (Organic Texel x Suffolk lamb (Ovis aries)) in a sandy loam soil. Measurements of decomposition processes included muscle tissue mass loss, microbial CO2 respiration, and muscle tissue carbon (C) and nitrogen (N). Muscle tissue mass loss at 22 degrees C always was greater than at 12 degrees C (p < 0.001). Microbial respiration was greater in samples incubated at 22 degrees C for the initial 21 days of burial (p < 0.01). All buried muscle tissue samples demonstrated changes in C and N content at the end of the experiment. A significant correlation (p < 0.001) was demonstrated between the loss of muscle tissue-derived C (Ct) and microbially-respired C (Cm) demonstrating CO2 respiration may be used to predict mass loss and hence biodegradation. In this experiment Q10 (12 degrees C-22 degrees C) = 2.0. This method is recommended as a useful tool in determing the effect of environmental variables on the rate of decomposition of various tissues and associated materials.
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