| 1. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 2. |
- Goncalves, M. C., et al.
(författare)
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Local structure and near-infrared emission features of neodymium-based amine functionalized organic/inorganic hybrids
- 2005
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 109:43, s. 20093-20104
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Tidskriftsartikel (refereegranskat)abstract
- Nd3+-based organic/inorganic hybrids have potential application in the field of integrated optics. Attractive sol-gel derived di-urea and di-urethane cross-linked poly (oxyethylene) (POE)/siloxane hybrids (di-ureasils and di-urethanesils, respectively) doped with neodymium triflate (Nd(CF3SO3)(3)) were examined by Fourier transform mid-infrared (FT-IR), Raman (FT-Raman), Si-29 magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and photoluminescence spectroscopies, and small-angle X-ray scattering (SAXS). The goals of this work were to determine which cation coordinating site of the host matrix (ether oxygen atoms or carbonyl oxygen atoms) is active in each of the materials analyzed, its influence on the nanostructure of the samples and its relation with the photoluminescence properties. The main conclusion derived from this study is that the hydrogen-bonded associations formed throughout the materials play a major role in the hybrids nanostructure and photoluminescence properties.
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| 3. |
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| 4. |
- Carlos, L. D., et al.
(författare)
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Nanoscopic photoluminescence memory as a fingerprint of complexity in self-assembled alkyl/siloxane hybrids
- 2007
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 19:3, s. 341-348
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Tidskriftsartikel (refereegranskat)abstract
- A thermally activated photoluminescence memory effect, induced by a reversible order-disorder phase transition of the alkyl chains, is reported for highly organized bilayer alkyl/siloxane hybrids (see figure; left at room temperature, right at 120 degrees C). The emission energy is sensitive to the annihilation/formation of the hydrogen-bonded amide-amide array displaying a unique nanoscopic sensitivity (ca. 150 nm).
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| 5. |
- Nunes, S. C., et al.
(författare)
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Cationic and anionic environments in LiTFSI-doped di-ureasils with application in solid-state electrochromic devices
- 2008
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Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 345:1, s. 32-40
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Tidskriftsartikel (refereegranskat)abstract
- Fourier Transform mid-infrared and Raman spectroscopies were used to investigate the cation/polymer, cation/urea bridge, cation/anion and hydrogen bonding interactions in poly(oxyethylene) (POE)/siloxane di-ureasil networks prepared by the sol-gel route and doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Materials with compositions 200 >= n >= 5 (where n expresses the molar ratio OCH2CH2/Li+) were studied. The Li+ ions coordinate to the urea carbonyl oxygen atoms over the whole range of salt concentration considered. Bonding to the ether oxygen atoms of the POE chains occurs at n
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| 6. |
- Nunes, S. C., et al.
(författare)
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Spectroscopic and structural studies of di-ureasils doped with lithium perchlorate
- 2007
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 53:4, s. 1466-1475
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Tidskriftsartikel (refereegranskat)abstract
- Di-urea cross-linked POE/siloxane hybrid ormolytes (di-ureasils) doped with a wide concentration range of lithium perchlorate trihydrate (LiClO4 center dot 3H(2)O) (200 >= n >= 0.5, where n expresses the salt content in terms of the number of ether oxygen atoms per Li+ ion) have been analysed by Fourier transform infrared and Raman (FT-IR and FT-Raman, respectively) spectroscopies and X-ray diffraction (XRD). The results obtained lead us to conclude that the xerogels with n >= 5 are totally amorphous. At n
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| 7. |
- Nunes, S. C., et al.
(författare)
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Vibrational spectra and microstructure of poly(epsilon-caprolactone)/siloxane biohybrids doped with lithium triflate
- 2008
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860. ; 879:1-3, s. 72-80
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Tidskriftsartikel (refereegranskat)abstract
- Fourier Transform infrared (FT-IR) and Raman (FT-Raman) spectroscopies and Scanning Electron Microscopy (SEM) were used to investigate ionic association, hydrogen bonding and morphology in a family of sol-gel derived lithium triflate (LiCF3SO3)-doped di-urethane cross-linked poly(epsilon-caprolactone) (PCL(530))/siloxane hybrid electrolytes. The materials studied, with compositions infinity > n >= 0.5 (where n - composition - expresses the molar ratio of PCL(530) ester repeat units per Li+ ion), are non-porous and homogeneous. The Li+ ions interact with the urethane and ester carbonyl oxygen atoms within the whole range of salt concentration analyzed, promoting the formation of hydrogen-bonded aggregates. The composition dependence of the relative concentration of "free" anions and coordinated anions (weakly coordinated anions, Li+CF3SO3- ion pairs or [Li(CF3SO3)(2)](-) triplets, aggregates I ([Li-2(CF3SO3)](+)) and aggregates II ([Li-3(CF3SO3)](+)) in all the samples is in perfect agreement with the values of the room temperature ionic conductivity reported previously. (C) 2007 Elsevier B.V. All rights reserved.
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| 8. |
- Silva, M. M., et al.
(författare)
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Sol-gel preparation of a di-ureasil electrolyte doped with lithium perchlorate
- 2006
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 52:4, s. 1542-1548
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Tidskriftsartikel (refereegranskat)abstract
- Solid polymer electrolytes (SPEs) synthesized by the sol-gel process and designated as di-ureasils have been prepared through the incorporation of lithium perchlorate, LiClO4, into the d-U(2000) organic-inorganic hybrid network. Electrolytes with lithium salt compositions of n (where n indicates the number of oxyethylene units per Li+ ion) between ∞ and 0.5 were characterized by conductivity measurements, cyclic voltammetry at a gold microelectrode, thermal analysis and Fourier transform Raman (FT-Raman) spectroscopy. The conductivity results obtained suggest that this system offers a quite significant improvement over previously characterized analogues doped with lithium triflate [S.C. Nunes, V. de Zea Bermudez, D. Ostrovskii, M.M. Silva, S. Barros, M.J. Smith, R.A. Sá Ferreira, L.D. Carlos, J. Rocha, E. Morales, J. Electrochem. Soc. 152 (2) (2005), A429]. "Free" perchlorate ions, detected in all the samples examined, are identified as the main charge carriers in the sample that yields the highest room temperature conductivity (n = 20). In the di-ureasils with n ≤ 10 ionic association is favoured and the ionic conductivity drops.
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| 9. |
- Silva, N. J. O., et al.
(författare)
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Matrix assisted formation of ferrihydrite nanoparticles in a siloxane/poly(oxyethylene) nanohybrid
- 2005
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 15:4, s. 484-490
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Tidskriftsartikel (refereegranskat)abstract
- Matrix-assisted formation of ferrihydrite, an iron oxide hydroxide analogue of the protein ferritin core, in a sol-gel derived organic-inorganic hybrid is reported. The hybrid network (named diureasil) is composed of poly(oxyethylene) chains of different average polymer molecular weights grafted to siloxane domains by means of urea cross-linkages and accommodates ferrihydrite nanoparticles. Magnetic measurements, Fourier transform infrared and nuclear magnetic resonance spectroscopy reveal that controlled modification of the polymer molecular weight allows the fine-tuning of the ability of the hybrid matrix to assist and promote iron coordination at the organic-inorganic interface and subsequent nucleation and growth of the ferrihydrite nanoparticles whose core size (2-4 nm) is tuned by the amount of iron incorporated. The polymer chain length, its arrangement and crystallinity, are key factors in the anchoring and formation of the ferrihydrite particles.
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| 10. |
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