Subject artefacts

The procedures of methylmercury extraction and derivatisation have lately been subject to doubt, as some traditionally used methods have proven to induce artificial methylation of inorganic mercury, with the consequence that a workshop and a complete journal issue of Chemo-sphere were dedicated to this subject.Artefact methylmercury production has not only been shown to occur during extraction, but also during derivatisation, and has been studied using isotopically labelled Hg +. ... 

The saturated hydrocarbon moieties give lipids an aliphatic character, and thus hydro-phobic properties, which limit their loss from artefacts by water leaching. However, they are subject to chemical and microbiological alterations since they have a limited number of reactive sites, they are relatively less susceptible to structural modification and degradation than polysaccharides, proteins and nucleotides. 

ToF-SIMS is quite a new analytical tool for the study of organic materials from art and archaeological artefacts. Nevertheless, we will see that in the first published studies, its application can cover a great number of subjects and materials. 

In this connection, it must also be borne in mind that the deoxyribonucleic acids subjected to analysis have probably not been homogeneous. Deoxyribonucleic acids have been fractionated by making use of their different solubilities in normal saline,186 by extracting thymus nucleo-his-tone with sodium chloride solutions of increasing concentration,187 by ion-exchange,187 and also by adsorption of the polynucleotide onto histone immobilized on a kieselguhr support.123 It is possible, however, that these are artefacts, since it has been shown that deoxyribonucleic acid fractions extracted from calf-thymus nucleohistone may or may not vary in composition according to the previous treatment of the material.188... 

The nanostructured fossils seem now to be less likely from Martian nanobacteria and probably are artefacts of the mineral formation process. Ironically, however, the discovery of the nanofossils may have been responsible for the massive interest in astrobiology, causing NASA to found the subject almost overnight. 

Boeda et al. (1996) identified bitumen on a flint scraper and a Levallois flake, discovered in Mousterian levels (about 40 000 BP) at the site of Umm el Tlel in Syria. The occurrence of polyaromatic hydrocarbons such as fluoranthene, pyrene, phenanthrenes and chrysenes suggested that the raw bitumen had been subjected to high temperature. The distribution of the sterane and terpane biomarkers in the bitumen did not correspond to the well-known bitumen occurrences in these areas. In other studies of bitumen associated with a wide variety of artefacts of later date, especially from the 6th Millennium BC onwards, molecular and isotopic methods have proved successful in recognizing different sources of bitumen enabling trade routes to be determined through time (Connan et al., 1992 Connan and Deschesne, 1996 Connan, 1999 Harrell and Lewan, 2002). 

The second of these assumptions has been the subject of some debate (Budd et al., 1995a), and is discussed further below. Despite these possible complications, the method of lead isotope provenancing was applied enthusiastically to copper alloy artefacts, especially those from the Late Bronze Age of the Aegean (e.g., Gale and Stos-Gale, 1992, and references therein) up until the late 1990s, when this activity virtually ceased, in part because of the contradictory interpretations which were being proposed. 

These simplified propositions do not exhaust the subject, but serve to show up some of the fundamental reasons why it has proved so difficult to agree on what the facts really are. The experimentation required to prove that any observed phenomenon is not an artefact due to impurities is always extremely lengthy and tedious. 

In this context, one has to consider that these types of indirect assays are subjected to many variables that are difficult to control and interpretation of results is somewhat limited. Artefacts due to biological components like enzymes or cytochrome c within these assays may falsify the observed activities, and other possible... 

In some cases more complex reaction schemes may give rise to linear Scatchard plots (Conners, 1987), and nonlinear plots may arise from a number of experimental artefacts, e.g., failure to reach equilibrium at low ligand concentrations. The interpretation of this particular linearisation approach has been the subject of many articles to which the reader is referred for further insight (Boeynaems and Dumont, 1975 Norby et al., 1980 Klotz, 1982, 1983 Hulme, 1992). 

Routine measurements of d-d spectra are performed on solutions. If a suitable solvent cannot be found for a solid sample, a diffuse reflectance spectrum of a powdered sample can be taken. This is actually an absorption spectrum of the surface layers of the sample and is subject to a number of anomalies and artefacts. It is much better to study microscopic single crystals, preferably at low temperatures. Large crystals (if they can be grown) tend to absorb too strongly around band maxima small, thin (c. 0.01mm) plates are best. It is usually necessary to condense the incident beam by means of a lens in order to obtain detectable intensities of transmitted radiation. Thus the technique is more difficult and time-consuming than the familiar, routine solution measurement but it can provide much more information. 

The mind of the subject is transmitted back along the timeline of the artefact, until it can connect with a host mind of someone in contact with the artefact. For example, someone is using this jug, say, in the early nineteenth century. This jug s presence here in the system connects us to that moment in its past, enabling us to sit in the mind of anybody else whose life has brought them into contact with that jug. ... 

The concept of temperature compensation of metabolism at the whole animal level in poikilotherms has been subject to strong criticism by Holeton (1974, 1980) and especially by I.V. Ivleva (1981), who believed that such compensation was an artefact arising from inadequate acclimation. However, Ivleva s own experiments were carried out on aquatic invertebrates, not fish, and the data referred to standard metabolism rather than total or active. Note that total metabolism is that taking place in an animal in nature, active metabolism is that which supplies locomotory activity, standard metabolism is that observed in experiments, and basal metabolism is that in the resting state. Ivlev (1959) found that apparent adaptive reactions of animals are seen mostly in active, not standard or basal, metabolism. However, more recent work (Karamushko and Shatunovsky, 1993 Musatov, 1993) appears rather to favour the concept of I.V. Ivleva, that standard, not active, metabolism illustrates the adaptive reactions. 

Disposition in the Body. Rapidly but incompletely absorbed after oral administration bioavailability about 65%. Up to 90% of an intravenous dose is excreted in the urine, mainly as unchanged drug with up to 14% of the dose as a glucuronide conjugate. 2-Amino-4-chloro-5-sulphamoylanthranilicacid has been reported as a metabolite in several studies, but in other cases it has not been detected and it has been suggested that it is an analytical artefact produced during acid extraction procedures. In normal subjects, about 6 to 18% of a dose is eliminated in the faeces after intravenous administration this may be increased to about 60% in renal failure. 

The use of adsorption isotherms is subject to both theoretical and experimental limitations. There is effectively a minimum relative pressure value specific to each adsorbate (e.g. P/Pq = 0.42 for nitrogen, 0,2 for CCI4) which corresponds to the minimum value of the surface tension for the phase to remain in liquid form. Below this critical value, the liquid adsorbate is unstable and vaporises spontaneously, an effect represented on the desorption curves by a sharp drop in the adsorbed volume. Depending on the significance of this variation, the porous distribution calculated from the desorption data may show an artefact in the pore size domain corresponding to this process (3-4 nm in diameter). For a porous solid where this phenomenon occurs, it is advisable to study the adsorption curve. 

A puzzling reaction was recorded in a small hospitalized Canadian population of elderly subjects treated for scabies with a single dose of ivermectin (150-200 micrograms/kg). Within 6 months, 15 of the 47 patients had died. All those who died had developed a sudden change in behavior, with lethargy, anorexia, and listlessness before death (31). The effect may have been an artefact with some extraneous cause, and it is notable that other groups using this treatment for scabies have not recorded similar reactions. 

In this chapter, we will describe the make-up of just three textile materials, all natural fibres, and will further present the mechanisms of degradation of their principal components. Our selection of two of them is somewhat indulgent as they are each the focus of current research projects. However, since all three compose the fabric of key historic textiles which were recently the subjects of commissions completed by Conservation Services at the Textile Conservation Centre, our choice was all the more easily made. Here we are keen to place the science in context, and so use these artefacts to introduce the fibres and their chemistry of ageing through a conservation science perspective. 

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