| 1. |
- Nyström-Larsson, Ingalill, 1969, et al.
(författare)
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Materialanalys av sydsvenskt bonadsmåleri
- 2007
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Ingår i: Rapport: Sammanfattning av Riksantikvarieämbetets seminarieserie 2007 kring pågående FoU-projekt. ; , s. 23-24
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Bonadsmåleriet hade sin storhetstid 1750-1850, och var influerat av medeltida kalkmåleri och bildvävnad i kyrkorna. Bonaderna var temporära och prydde stugorna till fest. Motiven kan vara både bibliska och profana. Materialet är tyger (återanvända och hopfogade) och senare även papper. Mot slutet av perioden övergår hantverket i massproduktion. Tidigare har bonaderna framför allt studerats inom humaniora (exempelvis etnologi) och ett naturvetenskapligt perspektiv har saknats. Därför finns mycket knapphändiga uppgifter om materialet. Syftet med projektet är att: • Kartlägga materialanvändningen • Tolka och förstå materialutvecklingen • Klarlägga innehållet i de otydliga trivialnamnen • Bygga upp ett referensmaterial Genomförande Ett antal frågeställningar har satts upp inför studiet: • Vilka materialval har man gjort? • Skiljer måleriteknik, färg, materialval mellan bonader, och går det att urskilja geografiska skillnader eller är det en tidsmässig utveckling? • Kan bonader attribueras utifrån materialval och färgval? • Vad är det för pigment som döljs i trivialnamnen? Skriftliga källor räcker inte för att svara på dessa frågor utan måste komplet-teras med naturvetenskapliga analyser. Diskussion kring RÄA-seminariets specifika frågeställningar På vad sätt bidrar ert projekt till kunskapsuppbyggnaden inom ert område? • Projektet är också ett pilotprojekt och den kunskap som vinns kan också appliceras på annat än bonadsmåleri. Utifrån resultaten kan man också gå vidare och titta på handelsvägar, infrastruktur etc. • En referensdatabas byggs upp och kan kanske också användas för an-nat material. På vilket sätt skulle resultaten från ert projekt kunna tillämpas mer konkret inom kulturmiljösektorn? • Ett viktigt mål är att hitta analysmetoder som inte förstör materialet, och som helst kan göras på plats så att materialet inte behöver flyttas (Raman spektroskopi). • Som konstaterades ovan kan resultaten från den kemiska analysen visa att en sådan kan komplettera traditionella historiska metoder också inom andra områden än bonadsmåleri. Frågor och öppen diskussion • Ännu har man inte hittat några speciella pigment eller färger, men analysen är inte klar. • Analysmaterialet som valts ut är signerade bonader. • Eftersom uppbyggandet av referensdatabaser är centralt i konserva-torns arbete är det viktigt att sprida resultaten av projektet.
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| 2. |
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| 3. |
- Abu-Youssef, Morsy A.M., et al.
(författare)
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1D and 2D FeII Azide Coordination Polymers with Ferromagnetic Canting
- 2008
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; 2008:1, s. 112-118
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Tidskriftsartikel (refereegranskat)abstract
- The two compounds [FeII(pyridine)2(N3)2(H2O)] (1) and [FeII(4-acetylpyridine)2(N3)2] (2) were prepared. The X-ray crystal structures show end-to-end (EE) bridging azides in both cases with a 1D Fe-NNN-Fe chain for 1 and a 2D Fe-NNN-Fe net in 2. Both compounds show similar magnetic behaviour where the high-temperature data are consistent with antiferromagnetic couplings and the low-temperature data indicate ferrimagnetic ordering based on spin canting at 20 and 45 K. Compound 2 also shows a hysteresis loop. These findings are compared to the related 3D coordination polymer [Fe(N3)2(4,4'-bipyridine)]. According to network analyses the latter compound was shown to contain the new uninodal six-connected-network topology (510 · 64 · 7)-jsm.
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| 4. |
- Andersson, Markus, 1981
(författare)
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Imidazole containing polymers complexed with Cu2+ and Zn2
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An enormous problem for the shipping industry is fouling of marine organisms such as algae andbarnacles on the boat hull. The negative consequences for the society are both economical as well asenvironmental. To prevent fouling in general, biocides are typically incorporated directly into the paint.Premature leakage of the biocides is a drawback which reduces the lifetime of the coating and pollutes thesurrounding ecosystems.Microencapsulation is an efficient way of encapsulating active substances for controlling the release andthereby prolonging the antifouling properties of the coating. The rate of release into the marineenvironment is partly governed by the degree of swelling of the shell of the microcapsule. The swelling ofthe microcapsule shell, and hence the release of biocide, may be modified by utilizing imidazolecoordination chemistry towards metal ions in the shell material.The aim of this thesis has been to characterize such coordinating polymer complexes and evaluate theirmaterial properties, solubility characteristics and coordination chemistry as well as synthesising newmaterials. Furthermore it is of interest to outline the coordination properties of imidazole as a function ofsubstitution position since synthetic and natural imidazole ligands in polymers are typically substituted atposition 1 or 4.The coordinating polymer material was studied using DSC, mid-FTIR and far-FTIR vibrationalspectroscopy as well as simple ocular investigation. The coordination chemistry of the coordinatingpolymer material and related coordination compounds were evaluated by far-FTIR and EPR.The reaction between the polymer and the metal ions Cu2+ and Zn2+ cross-links the system and increasesthe glass transition temperature, Tg. Furthermore, the strong coordinate bond between imidazole and themetal ions in the cross-links renders the complex insoluble in conventional solvents, and only stronglycoordinating solvents are able to solubilise the complex. The geometry of the Cu2+ complexes is squareplanar with up to four imidazole ligands and the physical properties of corresponding the Zn2+ complexesindicate a higher coordination number. The metal ions are exclusively coordinated by the imidazole ligandin the polymer. Concerning the effect of ring substitution on the coordination chemistry of imidazole, theresults indicate that the inductive effect of the group attached has a much larger effect than the position ofthe group.ivDue to the significant strength of the coordinate bond, coordination of imidazole by Cu2+ or Zn2+ is anefficient way of almost irreversibly incorporating salts into a hydrophobic polymer material. Polymerscoordinated by metal ions provide the resulting coordinating polymer complex with new materialproperties. The specific aim of this doctoral project is to use these polymer materials to modify the shellof the microcapsule in order to control the rate of release. Due the strongly hygroscopic nature of salts,the tendency for the shell material to swell by water should be significantly enhanced. The contact with seawater will accordingly act as a trigger for release.
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| 5. |
- Borel, Cédric, 1979, et al.
(författare)
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catena-Poly[[bis(N,N'-dimethylformamide)cadmium(II)]-μ2-oxalato]
- 2008
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Ingår i: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E64:1, s. m185-
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Tidskriftsartikel (refereegranskat)abstract
- The title compound, [Cd(C2O4)(C3H7NO)2]n, is isostructural with its MnII analogue. The structure comprises zigzag polymeric chains with the oxalate groups situated on inversion centres and the CdII atoms located on twofold rotation axes.The coordination geometry around CdII is distorted octahedral and the intrachain Cd...Cd distance is 5.842(1) Å. C—H...O hydrogen bonds exist between the parallel polymeric chains.
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| 6. |
- Bergenstråhle, Malin, 1977-, et al.
(författare)
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Dynamics of Cellulose-Water Interfaces : NMR Spin-Lattice Relaxation Times Calculated from Atomistic Computer Simulations
- 2008
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Ingår i: Journal of Physical Chemistry B. - Washington : ACS Publications. - 1520-6106 .- 1520-5207. ; 112:9, s. 2590-2595
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy has often been used to study cellulose structure, but some features of the cellulose NMR spectrum are not yet fully understood. One such feature is a doublet around 84 ppm, a signal that has been proposed to originate from C4 atoms at cellulose fibril surfaces. The two peaks yield different T1, differing by approximately a factor of 2 at 75 MHz. In this study, we calculate T1 from C4-H4 vector dynamics obtained from molecular dynamics computer simulations of cellulose Iβ-water interfacial systems. Calculated and experimentally obtained T1 values for C4 atoms in surface chains fell within the same order of magnitude, 3-20 s. This means that the applied force field reproduces relevant surface dynamics for the cellulose-water interface sufficiently well. Furthermore, a difference in T1 of about a factor of 2 in the range of Larmor frequencies 25-150 MHz was found for C4 atoms in chains located on top of two different crystallographic planes, namely, (110) and (10). A previously proposed explanation that the C4 peak doublet could derive from surfaces parallel to different crystallographic planes is herewith strengthened by computationally obtained evidence. Another suggested basis for this difference is that the doublet originates from C4 atoms located in surface anhydro-glucose units with hydroxymethyl groups pointing either inward or outward. This was also tested within this study but was found to yield no difference in calculated T1.
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| 7. |
- Dunér, Gunnar, et al.
(författare)
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Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:14, s. 7559-7564
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.
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| 8. |
- Asplund, Basse, et al.
(författare)
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Effects of hydrolysis on a new biodegradable co-polymer
- 2006
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Ingår i: Journal of Biomaterials Science. Polymer Edition. - : Informa UK Limited. - 0920-5063 .- 1568-5624. ; 17:6, s. 615-630
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the feasibility of using a new low-modulus biodegradable thermoplastic elastomer for in vivo application as a stent cover. The new polymer, a thermoplastic elastomer, consists of a three-armed co-polymer of poly(lactide)acid (PLLA), poly(trimethylene carbonate) (PTMC) and poly(caprolactone) (PCL). A degradation study was performed in a buffer solution at 37 degrees C for 4 and 6 weeks. The effect of degradation on mechanical properties was studied by stress-strain measurements and explained by using modulated DSC, GPC and mass measurements. A tapered block of PLLA and trimethylene carbonate connecting the crystalline outer part and the inner elastic part was highly susceptible to hydrolysis and caused rapid degradation and subsequent loss of mechanical properties. Random chain scission and homogenous hydrolysis resulted in a loss in mass and molecular weight. After 6 weeks of in vitro hydrolysis the molecular weight had decreased 54% and the elongation-at-break dropped from more than 300% to 90%. A medium free cell seeding study showed that endothelial cells adhered well to the polymeric material. An indicative animal study with the polymer acting as a stent cover showed very low levels of inflammation however, pronounced neointima thickening was observed which was probably due to the premature failure of the material.
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| 9. |
- Bergenstråhle, Malin, 1977-, et al.
(författare)
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Thermal Response in Crystalline Iβ Cellulose : A Molecular Dynamics Study
- 2007
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Ingår i: Journal of Physical Chemistry B. - Washington : ACS Publications. - 1520-6106 .- 1520-5207. ; 111:30, s. 9138-9145
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Tidskriftsartikel (refereegranskat)abstract
- The influence of temperature on structure and properties of the cellulose Iβ crystal was studied by molecular dynamics simulations with the GROMOS 45a4 force-field. At 300 K, the modeled crystal agreed reasonably with several sets of experimental data, including crystal density, corresponding packing and crystal unit cell dimensions, chain conformation parameters, hydrogen bonds, Young's modulus, and thermal expansion coefficient at room temperature. At high-temperature (500 K), the cellulose chains remained in sheets, despite differences in the fine details compared to the room-temperature structure. The density decreased while the a and b cell parameters expanded by 7.4% and 6%, respectively, and the c parameter (chain axis) slightly contracted by 0.5%. Cell angles α and β divided into two populations. The hydroxymethyl groups mainly adopted the gt orientation, and the hydrogen-bonding pattern thereby changed. One intrachain hydrogen bond, O2'H2'···O6, disappeared and consequently the Young's modulus decreased by 25%. A transition pathway between the low- and high-temperature structures has been proposed, with an initial step being an increased intersheet separation, which allowed every second cellulose chain to rotate around its helix axis by about 30°. Second, all hydroxymethyl groups changed their orientations, from tg to gg (rotated chains) and from tg to gt (non-rotated chains). When temperature was further increased, the rotated chains returned to their original orientation and their hydroxymethyl groups again changed their conformation, from gg to gt. A transition temperature of about 450 K was suggested; however, the transition seems to be more gradual than sudden. The simulated data on temperature-induced changes in crystal unit cell dimensions and the hydrogen-bonding pattern also compared well with experimental results.
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| 10. |
- Bubnov, Alexej, et al.
(författare)
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Polar liquid crystalline monomers with two or three lactate groups for the preparation of side chain polysiloxanes
- 2006
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Ingår i: Liquid Crystals. - : Informa UK Limited. - 0267-8292 .- 1366-5855. ; 33:5, s. 559-566
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Tidskriftsartikel (refereegranskat)abstract
- Two new chiral liquid crystalline monomers with bilactate or trilactate chiral units were synthesized and studied. The monomers show the paraelectric SmA and ferroelectric SmC* phases. The antiferroelectric phase was detected only for the monomer possessing the bilactate unit. The temperature dependences of the spontaneous polarization and spontaneous tilt angle were measured. Real and imaginary parts of the complex permittivity were studied as a function of frequency and temperature. The synthesized monomers contain a double bond at the end of the achiral terminal chain, and were used to prepare liquid crystalline polysiloxanes.
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