Academic literature on the topic 'Paper conservation'

The paper presents the history and development of conservation of books, graphics and paper objects in Warsaw Poland, both in practical approach as well as in the process of teaching at the Academy of Fine Arts. The theoretical assumptions are followed by a review of chemical methods used today, but also abandoned ones. There were two turning points in the history of conservation in Warsaw: beginning co-operation with professional chemists at the Academy and developing the system of microbiological controls at the National Library. A short description of the most important conservation projects is included: Acid Paper and Energy Efficiency of Museums and Libraries.

Previous research has been carried out concerning the conservation of both historic buildings and library and archive collections. Little work has, however, been undertaken to look at the interface between the two. The following research has been carried out in the context of an interdisciplinary project linking key disciplines in an examination of the issues relating to conservation problems in historic buildings used for library and archive purposes. This thesis presents a comprehensive literature review, evaluating published data on both the preservation of paper-based collections in libraries and archives, and preventive conservation of historic buildings and monuments. Emphasis is given to the interface between the two. Furthermore, a survey of British archives and libraries has been carried out, including the evaluation of questionnaire and site data. The survey focuses on preventive conservation measures as well as past and present problems of dampness. This survey proved problems with dampness to be often misdiagnosed and the consequences of damage underestimated. From the surveyed collections, two case studies have been selected for environmental monitoring in order to investigate macro- and micro-climates under different environmental conditions. Resulting data suggest that the micro-environment of a confined space is influenced by the amount of paper housed within it. This has assisted in explaining the interaction between paper and the immediate environment. At the same time, data has confirmed that the overall surface area of paper available for environmental interaction is more important than paper type or book size, with respect to the overall conditions within the storage space. Although degradation mechanisms of paper with respect to cycling conditions are not entirely clear, results of this study emphasise the importance of ventilation and dehumidification in order to avoid mould germination and/or growth. The data have been used to determine whether the internal environment of enclosed bookcases, and hence the immediate environment of the collection, can be adequately predicted from ambient data taken within the room. Mathematical models have been developed for both metal and wooden bookcases, and have shown that even when the ambient conditions are unstable, the relationship between ambient RH and the RH inside a book in an enclosed bookcase can be predicted within a 5% margin (1% for a stable environment).

The freshwater crab fauna of Vietnam has a high diversity and endemism, 49 species have been recorded and 42 of them are only known from this country. In addition, many species are undescribed or undiscovered while at least 10% of known species are facing extinction. Water pollution, urban, industrial and agricultural development, habitat loss and fragmentation, deforestation and overexploitation are the main threats to this fauna. The first conservation recommendation is keeping rain forest tracts large enough to maintain habitat and water quality for long-term survival of these crabs. More research on taxonomy, distribution, population dynamics, main pressures, conservation status are needed in order to assess conservation status and create efficient conservation actions for freshwater crabs in Vietnam.
Khu hệ cua nước ngọt ở Việt Nam có mức độ đa dạng và đặc hữu cao với 49 loài đã được ghi nhận, trong đó có tới 42 loài chỉ được biết đến ở Việt Nam. Ngoài ra, nhiều loài cua nước ngọt còn chưa được mô tả hay chưa được khám phá, trong khi có tới 10% trong tổng số loài đã biết đang phải đối mặt với nguy cơ tuyệt chủng. Ô nhiễm môi trường nước, đô thị hóa, phát triển công nghiệp và nông nghiệp, nơi sống bị phân mảnh và mất, phá rừng cùng với khai thác quá mức là những mối đe dọa chính đối với khu hệ này. Công tác bảo tồn trước hết phải giữ cho diện tích rừng đủ lớn để duy trì chất lượng môi trường sống cho sự tồn tại lâu dài của các loài cua này. Các nghiên cứu về phân loại học, phân bố, động lực quần thể là rất cần thiết để đánh giá tình trạng bảo tồn và đưa ra những hành động bảo tồn hiệu quả cho các loài cua nước ngọt ở Việt Nam.

Cette thèse présente une étude historique : l’apparition du papier au Moyen Orient. L’identification des centres de fabrication papetières de cette région, les différentes méthodologies constatées, puisées dans des sources arabes anciennes. Une étude analytique : analyses des sujets présents dans les firmans d’Alep qui contiennent plusieurs sujets traitant de la vie politique, économique, religieuse, militaire et sociale de cette ville. Ces sujets nous donnent une idée plus claire et réelle de ce qui s’est passé dans cette région et d’une manière plus large dans l’empire ottoman. Une étude technique des papiers filigranés des collections ottomanes conservées au centre des archives de Damas : de manière à peu près constante, les papetiers d’Occident se sont appliqués à signer leur production en utilisant une marque inscrite en filigrane dans la feuille à sa fabrication. Cette marque qui s’exprime par le dessin d’une figure ou des lettres, constitue en quelque sorte l’enseigne du papetier. Des solutions de conservation préventive par la surveillance climatique et la sensibilisation des différents acteurs : chercheurs, responsables et lecteurs sur les bonnes pratiques de consultation. Des solutions de conservation curatives sont proposées par l’utilisation de méthodes de restaurations reconnues au niveau international et par la création d’un type de reliure de conservation économiquement et techniquement transposable en Syrie pays où cet artisanat est absent
This thesis presents a historical study: the appearance of the paper in the Middle East. Identification of paper mills manufacturing centers of this region, the different methodologies identified, drawn from ancient Arabic sources. An analytical study: analysis of subjects in the firmans Aleppo containing several topics dealing with political, economic, religious, military and social life of the city. These subjects give us a clearer and real idea of what happened in this region and more broadly in the Ottoman Empire. A technical study paper watermarks Ottoman collections housed at the center of Damascus archives: in order almost constant, papermakers west have applied to sign their production using a registered trademark implicit in the sheet manufacture. This brand is expressed through drawing of a figure or letters, is something of the sign in the paper. Preventive conservation solutions for climate monitoring and awareness of various stakeholders: researchers, managers and players on good consultation practices. Curative conservation solutions are offered by the use of methods restorations internationally recognized and the creation of a type of conservation economically and technically binding transposable Syria country where the craft is away

In this doctoral dissertation, photochemical and, in some cases, thermal aging (natural and accelerated) of materials from cultural heritage (paper, parchment, linseed oil paints, pigments and dyes) are studied with a number of both destructive and non-destructive experimental techniques such as Electron Paramagnetic Resonance (EPR) , Nuclear Magnetic Resonance-MObile Universal Surface Explorer (NMR-MOUSE) , High Performance Liquid Chromatography-Photo Diode Array (HPLC-PDA) , Liquid Chromatography-Mass Spectrometry (LC-MS) , Fiber Optics Reflectance Spectroscopy (FORS)3,1, Attenuated Total Reflectance-Infrared spectroscopy (ATR-IR) , micro-fading-meter3 and Xenotest exposure device3. My research activity was carried out in collaboration with the Chemical Sciences Department of the University of Padua, the Netherlands Institute for Cultural Heritage (Amsterdam) and the Image Permanence Institute (Rochester Institute of Technology, NY) and thanks to the accessibility to the Van Gogh Museum collection. In chapters one and two, an introduction to the history of colorants and to colorimetry and a description of the degradation reactions induced by light and by common gaseous pollutants are presented. In chapters three, four and five, the results of my research activity are analyzed. In particular, in chapter three of my doctoral dissertation, Writing Materials, the dependence of chemical-physical properties of paper and parchment on aging is investigated with an NMR device called MOUSE. NMR-MOUSE is an instrument of great potential in the field of conservation science because it enables the measurement of nuclear relaxation times of various materials in situ and without sampling. Nuclear relaxation times are directly related to the chemical-physical nature of materials and were proved to be markers of the state of conservation of paper. As for parchment, nuclear relaxation times enabled to distinguish between samples from the XX century and XVIII century. For both materials, different environments for water (bound or free molecules) could be recognized. In chapter four, Pigments and Dyes, a number of EPR spectra of known and unknown pigments is provided. In addition, the effect of different pigments or dyes on polymerization of linseed oil paints is revealed with NMR-MOUSE. EPR spectroscopy was demonstrated to be effective in discriminating different pigments or classes of pigments with micro-invasive sampling. Relaxation times of linseed oil paints were demonstrated to be sensitive to the presence of pigments and an interpretation of the results in terms of different rates or degree of polymerization was given. In chapter five, Dyes in Aqueous Solution and on Paper: Discoloration and Fading of Crystal Violet, which represents the main body of my doctoral research activity, an extensive analysis (HPLC-PDA, LC-MS, FORS, EPR, micro-fading assessments, Xenotest exposure device) of the photo-fading and thermal aging of an early synthetic dye (Crystal Violet) in aqueous solution and on paper is presented. The interest on the subject stems from the discoloration occurred on a group of Van Gogh drawings and letters all produced in 1888 in Arles and all made with a type of purple ink which was demonstrated to contain crystal violet and other structurally related derivatives (triarylmethane dyes). In particular, a seemingly brown drawing belonging to this group and entitled Montmajour (Arles, 1888. Van Gogh Museum) shows purple shades on the edges where the ink has been protected from light under the frame. Another example, although not belonging to the Arles group, is a menu (Paris, 1886. Van Gogh Museum) drawn and written by Van Gogh with purple ink, as can be inferred from a reproduction made in 1958. Nevertheless, in a picture of the menu taken in 2001 it can be seen that the writings and part of the drawings had disappeared entirely. Interestingly, although FORS analysis revealed the presence of ink containing triarylmethane dyes, in this case no brown discoloration was visible. With the aim of shedding light on aging mechanisms and discoloration of inks containing crystal violet on paper, accelerated aging experiments were conducted for pure crystal violet both in aqueous solution and on paper. Various experimental parameters were taken into consideration: the spectral range of the light source (UV or Vis), the paper substrate (pure cellulose paper, lignin paper, printing paper), temperature and the presence or absence of oxygen during irradiation. Moreover, a purple ink containing methyl violet (a mixture of crystal violet and some of its demethylated derivatives) was reconstructed (by Judith Geerts, student of the University of Amsterdam, according to a recipe by Sigmund Lehner, 1909) and its thermal (100 °C) and photo fading (UV light and natural sun light) was studied on different paper substrates (cellulose paper, lignin paper and protein-sized paper). The effect of various ink additives (gum arabic, sucrose and oxalic acid), of Fe(III) (as an example of photo-catalyst often present as an impurity in paper) and of common gaseous pollutants such as NO2 and O3, on the color of dyed (or written) samples of paper was also taken into consideration. A group of ten historical samples of methyl violet from the ICN dye collection was also analyzed with HPLC-PDA, with the aim of comparing actual dye samples with both the model samples described in this doctoral dissertation and with the purple ink of the ‘Montmajour’ drawing (Arles, 1888. Van Gogh Museum). Successively, some dyes and pigments (cochineal ink, indigo blue ink, indigo carmine, copper logwood synthesized from CuSO4 or Cu(AcO)2 and chromium logwood) used in the XIX century as alternative ingredients for purple inks were deposited on paper and artificially aged with UV light or heat. A colorimetric analysis of the samples was conducted before and after aging. Finally, a group of letters from the XIX century (Birgit Reissland, private collection) was analyzed with FORS and the presence of dyes closely related to crystal violet was detected. The analysis presented in chapter five of this doctoral dissertation has thus demonstrated that the synthetic dye methyl violet was widely used after its introduction to the market in 1866. Moreover, the poor lightfastness of crystal violet was explained to be due to demethylation and oxidation reactions. A series of degradation products was identified with HPLC-PDA and LC-MS both for crystal violet in aqueous solution and on paper after exposure to UV in the presence of oxygen. HPLC-PDA analysis of a sample of purple ink from the ‘Montmajour’ drawing (Arles, 1888. Van Gogh Museum) was in good agreement with the results of these model samples. The complete fading observed on the Menu was reproduced and explained as due to light exposure (UV or visible). According to my experimental results, the first stage of the degradation mechanism consists of a series of demethylation reactions eventually leading to pararosaniline, a red dye corresponding to fully demethylated crystal violet. Afterwards, oxidation at the central carbon atom forms colorless (or slightly yellow) ketones responsible both for the fading of crystal violet and for a sensitization effect on dye degradation. The presence of oxidized derivatives of Crystal Violet has also been demonstrated. As for the position of the oxygen attack, it has been hypothesized the formation of N-oxides of crystal violet or of its demethylated derivatives. Heat (50 °C, 40% relative humidity) was shown to play a minor role in the fading of crystal violet on paper whereas visible light alone was enough for the dye to fade visibly. Interestingly enough, considering the fact that anoxic protection is in use, crystal violet did fade on paper following the exposure to UV light in the absence of oxygen as well. The substrate (cellulose paper, lignin paper or printing paper), although it was not responsible for the nature of (colored) degradation products, played a role in determining the relative amounts products formed and the final color of the dye layer. Interestingly, both artificial aging (UV light) and natural aging (sun light) of samples of paper dyed with an ink containing methyl violet and other additives led to different colors than in the presence of pure crystal violet. In particular, the colors obtained were brownish-grey and bluish-grey, in the presence or in the absence of Fe(III) respectively. Moreover, the addition of Fe(III) or of ink additives (such as sucrose and oxalic) alone to paper, caused the formation of yellow or brown discoloration after exposure to sunlight. ATR-IR analysis of the yellow areas revealed the formation of carbonyl groups from cellulose and Fe(III). On the basis of the results of the aging tests of the reconstructed ink, an hypothesis for the brown discoloration of the Montmajour drawing is provided. Exposure to such a pollutant as NO2 of purple ink containing methyl violet applied on different paper substrates (cellulose paper, lignin paper and protein-sized paper) produced a strong darkening of ink which turned bluish-black or black on all substrates. On cellulose paper, pure crystal violet faded to light blue. LC-MS analysis of the dyes extracted from this sample revealed the formation of at least one nitrosamine, due to the attack of the gas at one of the nitrogen atoms of the dye molecule. Exposure to O3 did not lead to a significant color change of Crystal Violet on paper. Accelerated aging experiments on pigments and dyes used as alternative ingredients for purple inks have brought about significant discoloration effects. Among others, copper logwood produced from copper sulphate and logwood extract showed a color shift from blue to reddish-brown after aging (in particular after thermal aging) and indigo carmine has faded entirely after exposure to UV light. These experimental results therefore demonstrate the importance of reliable reconstructions of museum objects where the co presence of various components (e.g. additives, impurities, different paper substrate) can lead to peculiar interactions or color effects. To this regard, cooperation between natural scientists, art historians, conservators and restorers should be pursued both in order to get a complete characterization of a piece of artwork and so as not to misinterpret partial data coming from a single research field.
La presente tesi di dottorato riguarda lo studio dei fenomeni di invecchiamento naturale e accelerato di tipo foto-chimico (e in alcuni casi termico), di materiali di interesse artistico (carta, pergamena, colori a olio, pigmenti e coloranti) attraverso numerose tecniche sperimentali, sia distruttive che non, quali Electron Paramagnetic Resonance (EPR) , Nuclear Magnetic Resonance-MObile Universal Surface Explorer (NMR-MOUSE) , High Performance Liquid Chromatography-Photo Diode Array (HPLC-PDA) , Liquid Chromatography-Mass Spectrometry (LC-MS) , Fiber Optics Reflectance Spectroscopy (FORS)3,1, Attenuated Total Reflectance-Infrared spectroscopy (ATR-IR) , micro-fading-meter3 e camera per test di invecchiamento solare accelerato Xenotest3. La mia attività di ricerca è stata svolta in collaborazione con il Dipartimento di Scienze Chimiche dell’Università degli Studi di Padova, il Netherlands Institute for Cultural Heritage di Amsterdam (ICN) e l’Image Permanence Institute (Rochester Institute of Technology, New York) e grazie all’accessibilità alla collezione del Museo Van Gogh di Amsterdam. Il primo e il secondo capitolo forniscono una introduzione alla storia dei coloranti e alla colorimetria e una descrizione delle reazioni di degrado indotte dalla luce e da comuni gas inquinanti. Nei capitoli numero tre, quattro e cinque, vengono invece presentati i risultati della mia attività di ricerca. In particolare, nel terzo capitolo della mia tesi di dottorato, intitolato ‘Materiali Scrittori’, viene analizzata la dipendenza di proprietà chimico-fisiche della carta e della pergamena dall’invecchiamento, attraverso l’uso di una sonda NMR nota come MOUSE. Lo strumento NMR-MOUSE ha dimostrato di avere grandi potenzialità nel campo della scienza della conservazione in quanto permette di misurare i tempi di rilassamento nucleari di svariati materiali in situ e senza alcun campionamento. I tempi di rilassamento nucleari dipendono dalla natura chimico-fisica dei materiali ed è stato dimostrato come costituiscano anche degli indicatori dello stato di conservazione della carta. Per quanto riguarda la pergamena, i tempi di rilassamento nucleari hanno permesso di discriminare fra campioni del XX secolo e del XVIII secolo. Inoltre, per entrambi i materiali, lo strumento NMR-MOUSE ha permesso di individuare due intorni chimico-fisici per le molecole d’acqua costituenti i materiali stessi. Si tratta, nel primo caso, di molecole d’acqua libere (acqua liquida) e, nel secondo, di molecole legate chimicamente al substrato cellulosico o proteico. Nel quarto capitolo, intitolato ‘Pigmenti e Coloranti’, sono riportati svariati spettri EPR di pigmenti e coloranti, la cui natura chimica era nota solo in alcuni casi. Inoltre, con lo strumento NMR-MOUSE è stato osservato l’effetto della presenza di diversi pigmenti o coloranti sulla polimerizzazione dell’olio di lino. La spettroscopia EPR si è dimostrata efficace nel discriminare fra diversi pigmenti o classi di pigmenti anche con campionamenti micro-invasivi. Inoltre, i tempi di rilassamento nucleari di colori a base di olio di lino si sono dimostrati essere dipendenti dalla presenza dei pigmenti e i risultati sono stati interpretati in termini di diverse velocità o gradi di polimerizzazione. Il quinto capitolo, intitolato ‘Dyes in Aqueous Solution and on Paper: Discoloration and Fading of Crystal Violet’, rappresenta il corpo principale di questa tesi di dottorato e consiste in un’estesa analisi (HPLC-PDA, LC-MS, FORS, EPR, valutazioni di micro-fading, camera per test di invecchiamento solare accelerato Xenotest) dei processi di invecchiamento foto-indotto e termico di uno dei primi coloranti organici sintetici, il crystal violet, in soluzione acquosa e su carta. L’interesse per questo argomento ha origine dall’osservazione dei fenomeni di alterazione cromatica che interessano un gruppo di disegni e lettere di Van Gogh, tutti prodotti ad Arles nel 1888 con un inchiostro viola che è stato dimostrato contenere crystal violet o altri coloranti strutturalmente correlati (coloranti del triafenilmetano). In particolare, il ‘Montmajour’ (Arles, 1888. Van Gogh Museum), ¬un disegno apparentemente di colore marrone e appartenente al detto gruppo, mostra delle tracce di inchiostro viola sui bordi del foglio, dove l’inchiostro è stato protetto dalla luce sotto la cornice. Un altro esempio, anche se non appartenente al gruppo di Arles, è costituito da un menù (Parigi, 1886. Museo Van Gogh) scritto e disegnato da Van Gogh con un inchiostro viola, come è stato possibile stabilire da una riproduzione dell’opera risalente al 1958. Tuttavia, in una foto del 2001 si può constatate come il testo e parte del disegno fossero completamente sbiaditi. E’ interessante notare come in questo caso, benché da un’analisi con spettroscopia FORS siano state rilevate tracce di coloranti del trifenilmetano, non si è osservato l’imbrunimento dell’inchiostro tipico del ‘Montmajour’. Con l’obiettivo di far luce sui meccanismi di invecchiamento e di alterazione cromatica degli inchiostri contenenti crystal violet su carta, sono stati condotti degli esperimenti di invecchiamento accelerato di crystal violet puro, sia in soluzione acquosa che su carta. Numerosi parametri sperimentali sono stati presi in considerazione: l’intervallo spettrale della sorgente di luce (UV o visibile), il substrato cartaceo (di pura cellulosa, contenente lignina o da fotocopie), la temperatura e la presenza (o assenza) di ossigeno durante l’irraggiamento. Inoltre, è stato riprodotto (da parte di Judith Geerts, studentessa dell’Università di Amsterdam) un inchiostro viola a base di methyl violet (a base cioè di una miscela di crystal violet e alcuni dei suoi prodotti di demetilazione) secondo una ricetta di Sigmund Lehner (1909) e il suo degrado foto-indotto (luce UV e luce solare naturale) e termico (100 °C) è stato studiato su diversi substrati cartacei (carta di cellulosa, carta di lignina e carta collata con proteine). Inoltre, sono stati presi in considerazione anche gli effetti, sul colore di campioni di carta tinta, di alcuni additivi utilizzati negli inchiostri (gomma arabica, saccarosio e acido ossalico), del Fe(III) (come esempio di foto-catalizzatore spesso presente nella carta come impurezza) e di comuni gas inquinanti, quali NO2 e O3. E’ stato analizzato via HPLC-PDA anche un gruppo di dieci campioni storici di methyl violet provenienti dalla collezione dell’ICN al fine di poter confrontare campioni reali di coloranti sia con i campioni modello descritti nella presente tesi di dottorato che con un campione dell’inchiostro viola del disegno ‘Montmajour’ (Arles, 1888. Museo Van Gogh). Successivamente, sono stati depositati su carta e invecchiati artificialmente (con luce UV o per trattamento termico) alcuni pigmenti e coloranti (inchiostro a base di cocciniglia o indaco, carminio d’indaco, colorante a base di estratto di campeggio e cromo e colorante a base di estratto di campeggio e rame sintetizzato a partire da CuSO4 o Cu(AcO)2) utilizzati nel XIX secolo come ingredienti per la produzione di inchiostri viola in alternativa al crystal violet. Infine, è stato analizzato con la spettroscopia FORS un gruppo di lettere del XIX secolo (Birgit Reissland, collezione privata) ed è stata rivelata la presenza di coloranti strettamente correlati al crystal violet. L’analisi presentata nel quinto capitolo della presente tesi di dottorato ha quindi dimostrato che l’uso del colorante sintetico methyl violet era molto diffuso dopo la sua introduzione nel mercato avvenuta nel 1866. Inoltre, la scarsa resistenza alla luce del crystal violet è stata spiegata come dovuta a reazioni di demetilazione e ossidazione. Una serie di prodotti di degrado è stata identificata con HPLC-PDA e LC-MS per il crystal violet esposto a luce UV in presenza di ossigeno, sia in soluzione acquosa che su carta. L’analisi HPLC-PDA di un campione di inchiostro viola prelevato dal disegno ‘Montmajour’ (Arles, 1888. Museo Van Gogh) si è dimostrata in accordo con i risultati dei campioni modello appena descritti. Lo sbiadimento completo osservato nel menù è stato riprodotto e spiegato come il risultato dell’esposizione alla luce (UV o visibile). Sulla base dei miei risultati sperimentali, il primo stadio del meccanismo di degrado consiste di una serie di reazioni di demetilazione che porta come ultimo stadio alla pararosaniline, un colorante rosso corrispondente alla completa demetilazione del crystal violet. Successivamente, l’ossidazione in corrispondenza dell’atomo di carbonio centrale forma chetoni incolore (o debolmente gialli), responsabili sia dello sbiadimento del crystal violet che di un effetto di sensibilizzazione del colorante rispetto al degrado foto-indotto. E’ anche stata rivelata la presenza di derivati ossidati del crystal violet. Per quanto riguarda la posizione dell’attacco da parte dell’ossigeno, è stata ipotizzata la formazione di N-ossidi del crystal volet o dei suoi prodotti di demetilazione. Si è dimostrato anche come il calore (50 °C, 40% umidità relativa) abbia un ruolo secondario nel degrado del crystal violet su carta mentre l’esposizione a sola luce visibile è stata sufficiente a sbiadire completamente il colorante. Particolarmente interessante, considerato che la protezione in ambiente anossico è una delle tecniche di conservazione adottate nei musei, è il fatto che il crystal violet ha mostrato evidenti segni di sbiadimento anche a seguito di esperimenti di esposizione a luce UV in assenza di ossigeno. Il substrato cartaceo (carta di cellulosa, di lignina o da fotocopie), benché non responsabile per la natura dei prodotti di degrado (colorati) rivelati, ha determinato le quantità relative dei prodotti formati e il colore assunto dallo strato di colorante. E’ interessante notare come sia l’invecchiamento artificiale (luce UV) che quello naturale (alla luce del sole) di campioni di carta tinti con l’inchiostro contenente methyl violet e altri additivi, abbiano dato origine a colorazioni diverse da quella ottenuta in presenza di crystal violet puro. In particolare, i colori ottenuti sono un grigio-bruno o un grigio-blu, rispettivamente in presenza e assenza di Fe(III). Inoltre, la sola aggiunta di Fe(III) o additivi (tipo saccarosio o acido ossalico) alla carta ha causato la formazione di macchie gialle o brune dopo l’esposizione alla luce solare. L’analisi ATR-IR delle aree ingiallite ha rivelato la formazione di gruppi carbonilici a partire da cellulosa e Fe(III). Sulla base dei risultati dei test di invecchiamento dell’inchiostro ricostruito, è stato possibile formulare un’ipotesi per spiegare le cause del colore bruno apparso sul ‘Montmajour’. L’esposizione ad un inquinante quale il biossido di azoto (NO2) dell’inchiostro a base di methyl violet applicato su diversi substrati cartacei (di cellulosa, di lignina o collati con proteine) ha prodotto un forte scurimento dell’inchiostro, che è diventato nero-blu o nero, in tutti i substrati cartacei. Per quanto riguarda invece il crystal violet puro, si è ottenuto uno sbiadimento ad azzurro chiaro su carta di pura cellulosa. L’analisi LC-MS di quest’ultimo campione ha rivelato la presenza di almeno una nitrosoammina dovuta all’attacco del gas su uno degli atomi di azoto della molecola di colorante. L’esposizione ad ozono (O3) non ha invece prodotto una variazione significativa del colore del crystal violet puro su carta. Gli esperimenti di invecchiamento accelerato sui pigmenti e i coloranti utilizzati come ingredienti alternativi per la preparazione di inchiostri viola, hanno condotto a importanti alterazioni cromatiche. Fra gli altri, il colorante a base di estratto di campeggio e rame prodotto da solfato di rame ha mostrato una variazione di colore dal blu al bruno rossiccio a seguito dell’invecchiamento (termico in particolare) e il carminio d’indaco è sbiadito interamente dopo esposizione alla luce UV. Questi risultati sperimentali, quindi, hanno dimostrato l’importanza di avere a disposizione affidabili ricostruzioni degli oggetti museali, dove la compresenza di varie componenti (ad esempio additivi, impurezze, diversi substrati cartacei) può portare a particolari interazioni chimiche o influenzare il colore percepito. A questo proposito, sarebbe auspicabile la cooperazione fra scienziati, storici dell’arte, conservatori e restauratori, al fine di poter ottenere una caratterizzazione completa di un’opera d’arte e così da non malinterpretare i dati parziali provenienti da un singola campo di ricerca.

AbstractSince the 1950s, siderophores have been acknowledged as nature’s chelating powerhouse and have been given considerable attention concerning their crucial roles in microorganisms and plants for capturing non-bioavailable iron from aquatic and terrestrial environments, as well as for their applications in agriculture, health, and materials science and environmental research. In recent years, the exceptional affinity and complexing efficacy, as well as the high selectivity of these potent chelators towards iron(III), have led to investigations by researchers aiming at understanding their capacity for removing potentially harmful and aesthetically unacceptable iron stains from organic substrates in cultural heritage objects. In the context of the conservation of cultural heritage objects, potent chelators have been proposed to remove iron from surfaces by transferring it to the more soluble complexed phase. In this review, the origins and the types of bio-environments of siderophores as well as their structure and chemistry are investigated and related to the requirements of conservation. It is evident that, given the enormous potential that these chelators have, the research for their application in cultural heritage is at a preliminary level, and has to date been within the rather narrow context of cellulosic materials such as paper and wood. The results of research conducted to date are presented in this review and questions regarding the optimal use of siderophores as iron-removing agents are posed.

AbstractThis paper reconsiders the possibilities for heritage conservation through everyday practices found in temporary uses as relevant and cost-effective tools in a constantly transforming urban environment, contributing to a more sustainable urban development. For this aim, three of the author’s previous case studies of temporary uses in the city of Berlin are reconsidered from the perspective of heritage conservation through everyday practices and citizen participation. Berlin, with its rapidly changing urban environment since 1989, has been an experimental hub for countless temporary uses in a short period of time and therefore provides useful insights into the viability of temporary uses for urban heritage conservation from a variety of perspectives. This paper shows that temporary uses, especially ones that develop into permanent businesses, help to protect buildings from decay, revitalize neglected urban areas, contribute to the realization of the SDGs, and provide affordable spaces for cultural and social activities.

AbstractTransformation, transition, and paradigm shift are increasingly applied concepts in literature on climate resiliency to describe changes in society and the environment. Here, we considered mangroves to be dynamic socio-ecological systems, subject to increasing anthropogenic pressures that present complex challenges for the design of effective coastal governance. Analysing these systems through a participatory approach, we consulted a community who lives in close relationship with mangroves, the Alitas farmers of Infanta, Quezon Province, Philippines. This community has improved decision-making processes for the development of adaptation strategies to climate change. In turn, a sustainably managed and conserved mangrove forest promotes human well-being and resilience, particularly for those households whose livelihoods are dependent on the resources that mangroves provide. This paper examined the importance of mangrove land management that addresses climate change hazards. We synthesised various perspectives on the importance of mangrove conservation for enhancing climate resiliency by: (1) describing the climate-related hazards that affect local communities and mangroves; (2) describing socio-institutional structures influencing effective mangrove conservation and local resilience; and (3) identifying climate change adaptation strategies that promote local development and mangrove conservation. This paper establishes a collaborative management framework for future risk-resilience management that operates alongside coastal communities within the Philippines and across the global stage.

AbstractPower consumption is the major cost factor in data centers. It can be reduced by dynamically right-sizing the data center according to the currently arriving jobs. If there is a long period with low load, servers can be powered down to save energy. For identical machines, the problem has already been solved optimally by [25] and [1].In this paper, we study how a data-center with heterogeneous servers can dynamically be right-sized to minimize the energy consumption. There are d different server types with various operating and switching costs. We present a deterministic online algorithm that achieves a competitive ratio of 2d as well as a randomized version that is 1.58d-competitive. Furthermore, we show that there is no deterministic online algorithm that attains a competitive ratio smaller than 2d. Hence our deterministic algorithm is optimal. In contrast to related problems like convex body chasing and convex function chasing [17, 30], we investigate the discrete setting where the number of active servers must be an integral, so we gain truly feasible solutions.

Although Ankara gained international attention mainly after its declaration as Capital of the Turkish Republic in 1923, the city hosts many buildings and monuments from different historical eras. The remains of Roman, Byzantine, Seljuk and Ottoman Empires discovered in the center of the city, clearly bear witness to the rich and diverse heritage of the capital. However, this heritage appears as less documented, studied and even not properly conserved. The citadel of Ankara, which dominates the narrow streets of the old city has withstood its long history very well and today houses a small neighborhood made up of valuable Ottoman wooden buildings. The link to the Roman and Medieval periods is still tangible. The Roman theatre remains at the foot of the hill are still observable, while the stone columns and beams used in the construction of the walls in a later era. The aim of this paper is to document and present the different historical eras of the castle, focusing on the remains of the medieval era. Analyzing the key features of the castle and the previous intervention on it will support the identification of the potentials of the site. Finally, recommendations for future work of architectural preservation will be elaborated on the basis of national and international conservation guidelines.

The process of construction can be defined as an extensive system that builds the accommodations for people to settle in, as well as the construction of facilities that keep up the development process. Some of the main steps that the process would cover are the extracting and benefiting raw materials, manufacture of building materials and elements, the construction of the project run from viability to inspection, and the regulation and running process of the sites. The most profound challenges that many cities n Iraq share illustrate the consequences of urban growth. Thus, this study seeks to examine the aspects of sustainability that influence the decisions for the process of building up green building projects. A total number of fourty respondents have been requested to evaluate nine elements of building sustainability: life cycle evaluations, energy conservation and renewable energies, water conservation, environmentally friendly construction supplies and standards, depletion of waste materials, alleviation of toxic materials, adequate indoor ventilation, smart innovation, and sustainability in the development of the building process and ecologically friendly construction projects. The findings show that the respondents preferred the use of elements that could give better sustainability in the process of construction building to ensure a healthier and better quality of life. This preference is established from the concept of green building technology. The most chosen aspect for this concept is the efficiency of energy and the use of renewable energy, followed by the alleviation of toxic materials, adequate indoor ventilation, and water conservation.

Traditional architecture style represents the evolutionary style and experienced characteristics of an urban environment that give a sense of place and identity. This style includes a mixture of technical and cognitive values that are difficult to conserve compared to other material resources. The process of organizing and classifying the architectural elements of these constructions in virtual digital manner is one of the means of preventive conservation for such elements and their values, which is essential in conservation operations of the built heritage. The study analyzes a number of international experiments that have employed shape grammar in studying and classifying the heritage elements in digital technique with specific rules. That because of the ability of these systems to examine the structure of the historic elements as it offers the possibility to combine their dimensional and morphological values, to classify them into a variety of categories with common characteristics in a specific style according to the local architectural language. The study seeks to determine the approaches of using the shape grammar as a mechanism of analyzing the structure of the elements of the Built heritage for classification. Next, to derive the rules and relationships that are used for the digital virtual reconstruction of the Built heritage according to the traditional architectural principles, and highlighting the digital applications and software that deals with the shape grammar in this field. The methodology of this study adopted the analysis of a number of studies that employed the shape grammar in the built heritage domain in order to review the potential of this digital systems and applications, to be presented as a documentation procedure for information management of preventive conservation projects of the urban environment in ancient cities.