The formation of adipocere in model aquatic environments.

An examination of the chemistry of adipocere formation in aquatic systems provides insight into how environmental factors affect the decomposition processes of human remains. Gas chromatography­mass spectrometry (GC-MS) and inductively coupled plasma­mass spectrometry (ICPMS) have been employed to monitor the changes to the chemistry of adipocere formed in aquatic environments used to model seawater, river and chlorinated water systems. Seawater was shown to inhibit adipocere formation, and a distinctively different elemental composition was produced in this environment due to the high concentrations of salts. By comparison, river water has been shown to accelerate the formation of adipocere. Chlorinated water appears to significantly enhance adipocere formation, based on a comparison with established fatty acid concentration values. However, a competing reaction to form chlorohydrins in chlorinated water is believed to be responsible for the unusual findings in this environment. The application of the chemical characterization of adipocere to an understanding of how this particular decomposition product forms in different water environments has been demonstrated, and there is potential to utilise this approach to identify the environment in which a body has been immersed.

Neutron diffraction of deuterated tripalmitin and the influence of shear on its crystallisation.

This neutron diffraction study of deuterated tripalmitin has provided further insight into a forensic observation of the crystallisation of lipids under high-shear conditions. To achieve this, an experimental set up was designed to enable simultaneous rheological data from a Couette cell to be recorded with neutron powder diffraction, enabling the influence of shear on the polymorph transformation on cooling to be monitored in real time. Tripalmitin was observed to directly transform from a liquid phase to a ß polymorph under the influence of shear. Although the liquid to ß transition was not observed to be influenced by shear rate, the degree of crystallinity, qualitatively denoted by an increase in the sharpness of the diffraction peaks, was observed at higher shear rates. Evidence is also presented that the rate of cooling influences the ordering in the ß-polymorph produced in zero shear conditions.

A spectroscopic investigation of the weathering of a heritage Sydney sandstone.

Infrared spectroscopy has been employed in a study of the degradation of heritage Sydney sandstone used in St. Mary's Cathedral in Sydney, Australia. Spectra were used to characterise the clay components taken from weathered and unweathered sandstone blocks removed from the Cathedral as part of a restoration programme. Two types of kaolin clays - kaolinite and its polymorph, dickite - have been identified. A higher amount of dickite present in the clay of weathered sandstone indicated that a kaolinite-to-dickite transformation occurs upon weathering. X-ray photoelectron spectroscopy was also used to confirm the presence of a more thermally stable polymorph of the kaolinite in the sandstone.

Two-dimensional analysis of the redox state of the rat cerebral cortex in vivo by NADH fluorescence photography.

A photographic method for measuring two-dimensional changes in NADH fluorescence and hemoglobin distributions in the rat cerebral cortex in vivo has been developed. Intracellular NADH was excited by UV light peaking at 360 nm and the emission was observed through a window with the maximum transmission at 450 nm. The fluorescence photographs (360 leads to 450 nm) required 20-25 sec exposures at the aperture opening of f/5.6 and the reflectance photographs (360 leads to 360 nm) 10 sec exposures at f/32. The digitization of photographic images was achieved either by a PDP-8-controlled microdensitometer coupled to an A/D converter or by a combination of a manually operated microdensitometer and a computer-controlled digitizer. In the latter case, a photographic negative was scanned with a Joyce-Loebl microdensitometer in parallel lines 170 mum apart, and the densitometric tracings were digitized with a PDP-8-controlled TV digitizer. The digital data were processed by DEC PDP-10 computer and the results were displayed in 3-dimensional surfaces. Nitrogen anoxia caused increases in fluorescence at 450 nm ranging from 10 to 75% fo the normoxic fluorescence intensities (after correcting for the logarithmic characteristics of the photographic films) and decreases in reflectance intensities in the range of 10-30%. The spatial resolution of the present technique is limited to approximately 30 mum X 30 mum on the cortical surface and the time resolution to 10-25 sec. The optical properties of the cerebral cortex in vivo appear to be controlled primarily by blood vessel patterns and hemodynamic factors and secondarily by the redox state of the tissue. Evidence for a heterogeneous redox response of the cerebral cortex toward N2 anoxia was obtained.

The identification of adipocere in grave soils.

Soil samples recovered from grave exhumations have been analysed in an attempt to identify and characterise adipocere contained in the samples. The soil samples were collected from different environments, including samples recovered from forensic grave sites. Gas chromatography-mass spectrometry (GC-MS) was employed to identify adipocere and characterise the fatty acid composition. X-ray diffraction was used to characterise the soil environments.

Study of the CN1 peptide of P2 protein using Fourier transform infra-red spectroscopy.

The conformation of the CN1 peptide, derived from the nervous system P2 protein, has been studied in deuterium oxide solution using Fourier transform infra-red (FTIR) spectroscopy. The peptide was found to be mainly random, with some alpha-helix and beta-structure present. The open structure of CN1 indicates that the constraints necessary for formation of the largely beta-structure in P2 are removed by cleavage of the protein to form peptides. The study produced different quantitative estimations of secondary structures to those previously reported in circular dichroism studies, but the FTIR results are shown to be more reliable.

The effect of soil texture on the degradation of textiles associated with buried bodies.

There are many factors which affect the rate of decomposition in a grave site including; the depth of burial, climatic conditions, physical conditions of the soil (e.g. texture, pH, moisture), and method of burial (e.g. clothing, wrappings). Clothing is often studied as a factor that can slow the rate of soft tissue decomposition. In contrast, the effect of soft tissue decomposition on the rate of textile degradation is usually reported as anecdotal evidence rather than being studied under controlled conditions. The majority of studies in this area have focused on the degradation of textiles buried directly in soil. The purpose of this study was to investigate the effect of soil texture on the degradation and/or preservation of textile materials associated with buried bodies. The study involved the burial of clothed domestic pig carcasses and control clothing in contrasting soil textures (silty clay loam, fine sand and fine sandy loam) at three field sites in southern Ontario, Canada. Graves were exhumed after 2, 12 and 14 months burial to observe the degree of degradation for both natural and synthetic textiles. Recovered textile samples were chemically analyzed using infrared (IR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the lipid decomposition by-products retained in the textiles. The findings of this study demonstrate that natural textile in contact with a buried decomposing body will be preserved for longer periods of time when compared to the same textile buried directly in soil and not in contact with a body. The soil texture did not visually impact the degree of degradation or preservation. Furthermore, the natural-synthetic textile blend was resistant to degradation, regardless of soil texture, contact with the body or time since deposition. Chemical analysis of the textiles using GC-MS correctly identified a lipid degradation profile consistent with the degree of soft tissue decomposition. Such information may be important for estimating time since deposition in instances where only grave goods and associated materials are recovered from a burial site.

Studies of adipocere using attenuated total reflectance infrared spectroscopy.

Attenuated total reflectance (ATR) infrared spectroscopy has been used to characterize pig adipocere formation. The compositions of adipocere samples obtained by burial of pig adipose tissue in soil and in mock coffins were compared with that of the original adipose tissue using this technique. The ART spectra show that bands resulting from triglyceride and fatty acid C=O stretching are particularly useful for monitoring the changes in adipocere formation. The technique is able to be used to investigate how the burial environment affects the rate of adipocere formation and supports the results of earlier gas chromatograph and mass spectrometer and diffuse reflectance infrared studies. ATR spectroscopy has also been demonstrated to have the advantage of convenient sample preparation.

A Fourier transform infrared spectroscopic study of P2 protein in reconstituted myelin.

The secondary structure of P2 protein, isolated from bovine peripheral nervous system myelin, in reconstituted myelin was studied using Fourier transform infrared (FTIR) spectroscopy. Spectra of the protein in aqueous solution and in the lipid environment were compared and notable changes were observed. It was proposed that there are significant differences in the conformation of the protein in the contrasting environments. An increase in alpha-helical structure was observed for the protein in myelin and the significant amount of beta-structure observed in aqueous solution was reduced. The degree of alpha-helix appears to be related to the neuritogenic activity of the P2 protein. The findings of this study also support the view that the presence of both alpha-helices and beta-structure plays a significant role in membrane proteins.

A Fourier transform infrared spectroscopic study of the secondary structure of myelin basic protein in reconstituted myelin.

The secondary structure of myelin basic protein (MBP) in reconstituted central nervous system myelin was studied using Fourier transform infrared (FTIR) spectroscopy. The spectra of the protein in aqueous solution and in the lipid environment were compared and notable differences were observed. It is proposed that there are significant differences in the conformation of the protein in the contrasting environments. Significant increases in both alpha-helical structure and beta-structure were observed on reconstitution in myelin. The findings of this study also support the view that the presence of both alpha-helices and beta-structure plays a important role in membrane proteins.

Denaturation studies of P2 protein using circular dichroism.

The denaturation process of P2 protein has been investigated using circular dichroism spectroscopy. The influence of temperature and the presence of urea were the factors investigated. Increasing temperature causes the destruction of beta-structure, while helical structure remains intact even at relatively high temperatures. Increasing the urea concentration destroyed all forms of secondary structure in P2 and the study also supports the model of a stepwise denaturation process of the protein.