15 research outputs found
Modern spectroscopic methods in non-invasive and micro-invasive analysis of paper degradation state
Papier został wynaleziony prawie 2000 lat temu i od tego czasu stał się najważniejszym
nośnikiem informacji dla ludzkości. W tym czasie zebrano ogromną ilość książek,
dokumentów i dzieł sztuki, z których wiele jest dziś bezcennych.
Pomimo rozwoju elektronicznych nośników informacji, znaczenie papieru nie zmniejsza się.
Popularność papieru wynika z jego wyjątkowych właściwości –
– wytrzymałości, elastyczności, trwałości i łatwej dostępności – które zawdzięcza celulozie,
swojemu głównemu składnikowi. Celuloza jest naturalnym polisacharydem składającym się
z jednostek β-D-glukopiranozy połączonych wiązaniami (1→4)-glikozydowymi.
Makrocząsteczki celulozy tworzą wielopoziomową strukturę, składającą się z fibryli
elementarnych, mikro- i makrofibryli, budujących ściany komórkowe włókien roślinnych,
które są głównym składnikiem papieru.
Wysokiej jakości papier, jeśli jest prawidłowo przechowywany, degraduje powoli i może
zachowywać swoje właściwości przez wieki. Jednakże papier słabej jakości w niekorzystnym
otoczeniu może ulec rozkładowy w czasie ludzkiego życia. Degradacja papieru w skali
makroskopowej objawia się jako żółknięcie i zwiększenie kruchości. Zmiany te są głównie
wywoływane przez hydrolizę wiązań glikozydowych i utlenienie, prowadzące do
powstawania grup karbonylowych. Hydroliza i utleniania są ściśle powiązane i mają
katalityczny wpływ na siebie. Ich postęp prowadzi do zmian na każdym poziomie struktury
włókien. Jedną z obserwowanych zmian jest rekrystalizacja polegająca na reorganizacji
makrocząsteczek celulozy w bardziej uporządkowaną strukturę. Mimo, że rekrystalizacja
nie jest procesem chemicznym, to możne wpływać na postęp hydrolizy i utleniania,
dlatego powinna być uwzględniona w ocenie postępu degradacji papieru.
W ramach niniejszej pracy opracowane zostały nowe metody analizy papieru,
których zastosowanie pozwala na bardziej miarodajną ocenę postępu degradacji papieru,
co pozwoliło również na pogłębienie zrozumienia mechanizmu degradacji celulozy
w kontekście zależności między warunkami starzenia, różnymi ścieżkami degradacji
i obserwowanymi jej skutkami.
Posłużyły temu sztucznie postarzone papiery modelowe oraz naturalnie zdegradowane
próbki średniowiecznych papierów ze szmat oraz papierów z transformatorów,
które przebadano za pomocą chromatografii żelowej (SEC), fourierowskiej spektroskopii
w podczerwieni (FT-IR), spektroskopii UV-VIS z wspomaganej obliczeniami TDDFT
(UV-VIS/TDDFT) oraz dyfraktometrii rentgenowskiej (XRD). Wybrane metody pozwalają
na ocenę stanu degradacji papieru przez określenie postępu depolimeryzacji, stężenia grup
karbonylowych i zmian w krystaliczności celulozy.Paper was invented almost 2000 years ago and ever since it has become the most
important information carrier for mankind. During this time an enormous amount of books,
documents and works of art have been collected and many those artifacts are invaluable.
Despite the development of electronic media, the importance of paper is not diminishing.
The popularity of paper is mostly related to its unique properties –
– strength, flexibility durability and availability – owed to the cellulose, its main component.
Cellulose is a natural polysaccharide composed of β-D-glucopiranose units linked
by (1→4)-glycosidic bonds. Macromolecules of cellulose form multileveled structure,
consisting of elementary fibrils, microfibrils and macrofibrils that build cell walls of plant
fibers, which are the main component of paper.
Quality paper, if stored properly, degrades extremely slowly and preserves its properties
for centuries. However, poor quality paper exposed to unfavorable environment can
disintegrate during human lifetime. Deterioration of paper on the macroscopic scale is seen
as yellowing and increasing brittleness. Those changes are induced primarily by hydrolysis
of glycosidic bonds and oxidation which leads to formation of carbonyl groups.
Hydrolysis and oxidation are interdependent and have a catalytic effect on each other.
Their progress leads to numerous changes on each level of fiber structure. The one those
changes is recrystallization is manifested by reorganization of cellulose macromolecules
into more ordered structure. Recrystallization is not a chemical process although it can affect
and be affected by hydrolysis and oxidation, therefore it is important to include it in assessing
paper degradation state.
In this study, the new methods were developed for paper analysis, which allow more
meaningful assessment of paper degradation state. The use of those methods helped to
increase the understanding the mechanism of cellulose degradation in terms of relationship
between aging conditions, different degradation paths and its observed effects.
To achieve the objectives artificially aged model papers were investigated along with
naturally aged samples of ancient rag papers and insulation papers, by means
of Size Exclusion Chromatography (SEC), Fourier-Transform Infrared Spectroscopy (FT-IR),
UV-VIS spectroscopy aided with TDDFT calculations (UV-VIS/TDDFT)
and X-Ray Diffractometry (XRD). The selection of methods allows the assessment of paper
degradation state by characterization of depolymerization progress, development of carbonyl
groups and recrystalization of cellulose
Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings
This study proposes a method to estimate the lipid content in binding media in paintings that can be used at any laboratory equipped with an infrared spectrometer. The lipid content estimator, termed greasiness index (GI), is defined as a ratio of lipid \nu(C=O) and protein amide I bands at 1743 and 1635 cm−1, respectively. Three Fourier transform infrared (FTIR) sampling techniques were evaluated for GI determination: reflective attenuated total reflection-ATR, specular reflection microscopy-\muSR and photoacoustic-PAS. A set of model painting samples containing three tempera binding media (casein, egg, egg + oil), seven pigments and one varnish type were used in the study. Multivariate analysis was used to evaluate the resulting data. A good reproducibility of GI was obtained by ATR and PAS but not with \mu SR. The discriminative power of the technique is higher for unvarnished samples, but, generally, the GI estimator can be used for the categorisation of binding media in large populations of painting samples analysed with the same FTIR technique (sampling technique, detection, etc.)
Circulating monocyte chemoattractant protein-1 in women with gestational diabetes.
Monocyte chemoattractant protein 1 (MCP-1) has been implicated as a key factor in the recruitment and activation of peripheral blood leukocytes in atherosclerotic lesions and adipose tissue. Elevated levels of circulating MCP-1 have been found in patients with type 1 and type 2 diabetes, as well as with coronary artery disease. In this study we compared serum MCP-1 concentrations between pregnant women with normal glucose tolerance (NGT), gestational diabetes mellitus (GDM) and non-pregnant healthy women. The group studied consisted of 62 patients with GDM (mean age 30.1 +/- 5.0 years) at 29.0 +/- 3.5 week of gestation, 64 pregnant women with NGT (mean age 30.0 +/- 4.7 years) at 29.2 +/- 2.9 week of gestation and 34 non-pregnant healthy women (mean age 29.8 +/- 4.7 years). Serum MCP-1 concentration was measured using an enzyme - linked immunosorbent assay. Median MCP-1 concentrations did not differ significantly between women with GDM (median 342.3 [interquartile range 267.9-424.4] pg/ml) and NGT (338.0 [274.7-408.2] pg/ml), but were markedly lower than those found in non-pregnant women (485.2 [409.6-642.4] pg/ml,
Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools
Experimental and theoretical study of the yellowing of ancient paper
Paper is the most widely used writing support due to the remarkable properties of its principal component -
cellulose - one of the most abundant biomaterials present on Earth. However, due to the complexity of the material,
an exhaustive picture of its degradation pathways is still missing. In this paper, we will present recent results and
progresses obtained in the comprehension of the role of cellulose oxidation in the yellowing of ancient paper. Visible
and ultraviolet spectra of cellulose in ancient paper samples and reference modern samples artificially aged have
been interpreted with the aid of ab-initio Time-Dependent Density Functional Theory calculations. Through the
comparison of measured and calculated absorption spectra, several oxidized forms of cellulose polymers, acting as
chromophores, and responsible for ancient paper yellowing were identified. The relative concentration of ketones
and aldehydic groups depends on the environmental conditions in which samples were stored along their life
Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings
La conservazione preventiva del patrimonio librario come possibile alternativa al restauro tradizionale
The present paper focuses on the close relation between library collections and their preservation environment, aiming, in particular, at highlighting the importance of promoting and sustaining the monitoring. The paper proposes some simple and ready-to-use technologies – smart monitoring – to prevent future damages
Evaluating paper degradation progress : cross-linking between chromatographic, spectroscopic and chemical results
Degradation markers of fibroin in silk through infrared spectroscopy
Infrared spectroscopy (FTIR) is a commonly available tool in laboratories dealing with both degradation
of materials and conservation of art objects to evaluate their condition. In this paper FTIR was engaged to
study degradation of
fi
broin included in silk samples (
Bombyx mori
) arti
fi
cially aged at various conditions
(oxygen, water vapor and volatile organic products) at temperature of 150
C. The results collected by
Attenuated Total Re
fl
ectance/Fourier Transform Infrared Spectroscopy (ATR/FTIR) were validated by UV/
Vis, XRD and SEC analyses. Based on the results, the degradation estimators were veri
fi
ed and classi
fi
ed
as: (1) crystallinity de
fi
ned as ratio of absorbance at 1620 and at 1656 cm
1
,
A
1620
/
A
1656
[1]
, or at 1620
and 1699 cm
1
,
A
1620
/
A
1699
[2]
; or ratio of areas under
fi
tted curves of band at 1261 and 1230 cm
1
,
P
1261
/
P
1230
[3]
, (2) oxidation
e
A
1620
/
A
1514
and (3) depolymerization
e
P
1318
/
P
1442
. Degradation gauges de
fi
ned
in such a way indicate that upon arti
fi
cial aging water vapor and oxygen has the most profound impact
on the progress of silk degradation. It also indicates that oxygen-lean conditions stabilize silk at elevated
temperature