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Iraci J.,Canadian Conservation Institute
Restaurator | Year: 2017

In a disaster event involving water, the length of time that collection materials remain wet is a critical factor in determining whether a successful recovery is possible. There is a substantial knowledge base for the water immersion resistance of traditional information carriers such as paper documents but not for electronic storage media. In this study, floppy diskettes, VHS videotapes, optical discs, and flash media, were immersed in different water baths for various time intervals. The baths consisted of two different sources of tap water, a more corrosive tap water solution, and artificial seawater. Most electronic media survived well in clean tap water but problems occurred with some CDs and VHS tapes. More damage became evident with electronic storage media when the immersion bath was more corrosive. For some media, such as optical discs, whether damage occurred was likely linked to the manufacturing quality of the media. Drying methods were also explored. Air-drying was determined to be the best method for recovering wet electronic storage media. Freeze-thaw-air drying and vacuum freeze-drying methods can destroy CDs and DVDs and should be avoided. If wet materials cannot be recovered and dried promptly, it was established that storage in cool water reduces deterioration significantly. © 2017 Walter de Gruyter GmbH, Berlin/Boston.

Hagan E.W.S.,Imperial College London | Hagan E.W.S.,Canadian Conservation Institute | Charalambides M.N.,Imperial College London | Young C.R.T.,The Courtauld Institute of Art, University of London | And 2 more authors.
Progress in Organic Coatings | Year: 2010

The tensile properties of latex coatings were investigated with a set of custom formulated artist-type paints at an age of 1 year. All films in the study contained a poly(methyl methacrylate-cobutyl acrylate) binder exhibiting a glass-transition at approximately 10 °C. The viscoelastic behaviour of the latex matrix is first highlighted through a series of experiments involving different strain histories and temperatures. Influence of the inorganic particle concentration and geometry is then illustrated using TiO2 and calcined kaolin for the secondary phase. Experimental data from a wide range of conditions are summarised through master curves of secant modulus and failure strains using time-temperature superposition. The results indicate that the latex films behave in a rheologically simple manner and it is possible to predict the response outside of the experimental time-scale. An analysis by similar methods is also given for TiO2 pigmented films with/without surfactant removed by immersion in water. Differential scanning calorimetry and atomic force microscopy were also used in conjunction with mechanical tests. The combined findings suggest that a fraction of surfactant migrates to the TiO2 interface during film formation, where it interferes with adhesion of the acrylic matrix. © 2010 Elsevier B.V.

Li J.F.,Xiamen University | Tian X.D.,Xiamen University | Li S.B.,Xiamen University | Anema J.R.,Xiamen University | And 9 more authors.
Nature Protocols | Year: 2013

Surface-enhanced Raman scattering (SERS) is a powerful fingerprint vibrational spectroscopy with a single-molecule detection limit, but its applications are generally restricted to 'free-electron-like' metal substrates such as Au, Ag and Cu nanostructures. We have invented a shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique, using Au-core silica-shell nanoparticles (Au@SiO2 NPs), which makes SERS universally applicable to surfaces with any composition and any morphology. This protocol describes how to prepare shell-isolated nanoparticles (SHINs) with different well-controlled core sizes (55 and 120 nm), shapes (nanospheres, nanorods and nanocubes) and shell thicknesses (1-20 nm). It then describes how to apply SHINs to Pt and Au single-crystal surfaces with different facets in an electrochemical environment, on Si wafer surfaces adsorbed with hydrogen, on ZnO nanorods, and on living bacteria and fruit. With this method, SHINs can be prepared for use in ~3 h, and each subsequent procedure for SHINERS measurement requires 1-2 h. © 2012 Nature America, Inc. All rights reserved.

Li J.-F.,Xiamen University | Anema J.R.,Canadian Conservation Institute | Wandlowski T.,University of Bern | Tian Z.-Q.,Xiamen University
Chemical Society Reviews | Year: 2015

Surface-enhanced Raman scattering (SERS) is a powerful technique that provides fingerprint vibrational information with ultrahigh sensitivity. However, only a few metals (gold, silver and copper) yield a large SERS effect, and they must be rough at the nanoscale. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was developed to overcome the long-standing materials and morphological limitations of SERS. It has already been applied in a variety of fields such as materials science, electrochemistry, surface science, catalysis, food safety and the life sciences. Here, the principles and applications of SHINERS are highlighted. To provide an understanding of the plasmonics involved, finite-difference time-domain (FDTD) calculations and single nanoparticle SHINERS experiments are reviewed. Next, various shell-isolated nanoparticle (SHIN) types are described. Then a number of applications are discussed. In the first application, SHINERS is used to characterize the adsorption processes of pyridine on Au(hkl) single-crystal electrode surfaces. Then, SHINERS' applicability to food inspection and cultural heritage science is demonstrated by the detection of parathion and fenthion pesticides, and Lauth's violet (thionine dye). Finally, graphene-isolated Au nanoparticles (GIANs) are shown to be effective for multimodal cell imaging, photothermal cancer therapy and photothermally-enhanced chemotherapy. SHINERS is a fast, simple and reliable method, suitable for application to many areas of science and technology. The concept of shell-isolation can also be applied to other surface-enhanced spectroscopies such as fluorescence, infrared absorption and sum frequency generation. © The Royal Society of Chemistry 2015.

Poulin J.,Canadian Conservation Institute | Helwig K.,Canadian Conservation Institute
Organic Geochemistry | Year: 2015

Class Ib resinites are the most common subclass of amber and are found throughout the world. They have a macromolecular structure based on co-polymerized communic acid, communol and biformenes. Because this class of resinite does not contain succinic acid, crosslinking of the polymer through esterification of communol moieties has never been theorized. Analysis of Class Ib resinites from Grassy Lake and Cedar Lake in western Canada was performed using pyrolysis-gas chromatography-mass spectrometry with in situ hexamethyldisilazane derivatization, using a thermal separation probe to perform the pyrolysis and sample introduction. This has allowed larger, more complex fragments to be released from the polymer matrix than previously possible using instantaneous pyrolysis methodologies. The results show for the first time that Class Ib resinite can undergo self-crosslinking between the communol and communic acid moieties in the polylabdane matrix. The chromatographic results also show that a portion of the monoterpenes and non-polymerizable diterpenes in the resinite are bound to the polymer matrix and not fully occluded as was previously theorized. Fourier transform infrared (FTIR) spectra of the resinites are presented and a more accurate spectral interpretation is proposed, based on the chromatographic results. © 2015.

Poulin J.,Canadian Conservation Institute | Helwig K.,Canadian Conservation Institute
Organic Geochemistry | Year: 2012

This paper describes a new sub-category of Class I resinites based on labdanoid diterpenes having an enantiomeric configuration, including ozic acid, ozol and enantio biformenes, and incorporating succinic acid. This hitherto unnamed resinite sub-class, now designated as Class Id, has been identified in three distinct deposits in Canada: two sites in Nunavut and one site in British Columbia. The composition of Class Id resinites was determined using pyrolysis-gas chromatography-mass spectrometry with in situ trimethylsilylation with hexamethyldisilazane, Py(HMDS)-GC-MS. Fourier transform infrared spectroscopy (FTIR) of the resinites was also carried out and provided evidence of partial esterification of the ozol with succinic acid. © 2011.

Iraci J.,Canadian Conservation Institute
Restaurator | Year: 2011

The desire to have a storage medium for digital information with a higher capacity than the CD has led to a growth in the use of DVD optical media. A single-layer DVD provides up to seven times more storage capacity than a CD and therefore makes it useful for the storage of larger digital files. However, due to some key structural differences between the DVD and CD formats, there are some unanswered questions with respect to the long-term stability of DVDs. This study examined the stability of a variety of movie DVDs, DVD±Rs, dual layer DVD+Rs, and DVD±RWs. These media were evaluated under accelerated aging conditions of 80°C and 85% relative humidity and by measuring error rate changes after four aging intervals of 21 days. It was demonstrated that erasable DVDs (DVD±RWs) and dual-layer recordable DVDs have fair and very poor stability respectively and should not be used if longevity of the optical media is required. On the other hand,the stability of recordable DVDs (DVD±Rs) ranged from very good to poor. Discs with good stability utilized a gold metal layer and a dye that was unaffected by the aging conditions. Recordable DVDs with a silver metal layer and less stable dye degraded quickly and cannot be recommended for the long-term storage of digital information. © 2011 De Gruyter Saur.

Tetreault J.,Canadian Conservation Institute | Dupont A.-L.,French Natural History Museum | Begin P.,Canadian Conservation Institute | Paris S.,French Natural History Museum
Polymer Degradation and Stability | Year: 2013

The reactivity towards cellulose of various volatile compounds commonly released by paper was studied. Sheets of Whatman No. 1 (W1) and No. 40 (W40) were exposed to various concentrations of these compounds in vapour phase ranging from 20 to 80 ppm in closed vessels for 52 days in controlled ambient conditions, after which they were hygrothermally aged. The measured properties of the paper were copper number, degree of polymerization, zero-span breaking length, pH and yellowness index. The results showed that hydrogen peroxide was the most aggressive among the volatile compounds tested as it severely degraded W1 cellulose. The exposure of W1 to formic acid led to significant degradation, designating this volatile organic compound (VOC) as the most reactive toward cellulose among the carboxyl and carbonyl functionalized VOCs tested. On the other hand, acetic acid was found comparatively less reactive. Nitrogen oxides, which were produced up to 3 ppm from a side-reaction of the carboxylic acids with the magnesium nitrate used to control the relative humidity in the closed vessels, appeared to contribute significantly to the degradation despite their low concentration. Antagonistic effects were evidenced in binary vapour mixtures where the presence of aldehydes (formaldehyde and acetaldehyde) counteracted substantially the degradation induced by the most reactive compounds. It was also shown that acetaldehyde, hexanal and furfural in individual exposures had little to no reactivity. Upon exposure to formaldehyde, the rate of glycosidic bond cleavage of cellulose induced by the ageing of W1 was significantly reduced. © 2013 Elsevier Ltd. All rights reserved.

Poulin J.,Canadian Conservation Institute | Helwig K.,Canadian Conservation Institute
Analytical Chemistry | Year: 2014

For the first time, molecular evidence of the structural role played by succinic acid within the macromolecular structure of Class Ia and Class Id resinite is presented. Using a novel gas chromatographic methodology, communol (Class Ia) and ozol (Class Id) moieties within the polylabdane matrix are shown to be cross-linked with succinic acid. Samples were analyzed using pyrolysis-gas chromatography-mass spectrometry with in situ hexamethyldisilazane derivatization, using a thermal separation probe to perform the pyrolysis and sample introduction. The relatively slow rate of heating and prolonged pyrolysis of resinites using this new methodology, combined with the use of a mild derivatization reagent, allowed communol pyrolysates from Class Ia resinite and ozol pyrolysates from Class Id resinite to elute with unbroken succinyl ester cross-linkages. These results provide direct molecular evidence that the key role of succinic acid within Class Ia and Class Id resinite is to cross-link the macromolecular structure. In the Class Id resinite, the methodology also allowed the detection of succinyl ester linkages between ozol pyrolysates and dehydroabietol, thus demonstrating that nonpolymerized diterpenes contribute structurally to the macromolecular structure of Class Id resinite. © 2014 American Chemical Society.

Iraci J.,Canadian Conservation Institute
Restaurator | Year: 2012

Storing optical discs in standard size jewel cases is the recommended method for protection from physical damage such as scratches and from contaminants such as dust, dirt, or fingerprints. However, there is some concern about the chemical effects that different jewel cases may have on CD or DVD media and about the possible negative impact caused by paper materials that are commonly placed in jewel cases. To examine these concerns, a variety of read-only CDs, recordable CDs, and recordable DVDs were tested. These discs were inserted into slim and standard size jewel cases with different types of holding trays and in jewel cases with acid or alkaline paper. The samples were aged at 80°C and 85% relative humidity for various intervals up to 84 days. Error rate analysis before and after the accelerated aging periods indicated that some jewel cases can negatively affect certain types of discs stored within them. It was also discovered that some discs emit volatiles during aging that if trapped in a jewel case promote the degradation of the discs. Storing a disc in a jewel case with a paper insert can promote disc degradation, retard it, or have no effect at all on the disc. This depends on the type of disc, on whether the insert paper material is acidic or alkaline, and whether the disc is off-gassing. © De Gruyter Saur 2012.

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