| 1. |
- Arias, Augusto, et al.
(författare)
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Simultaneous rotation, orientation and displacement control of birefringent microparticles in holographic optical tweezers
- 2013
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 21:1, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- We report the experimental implementation of a new method for generating multiple dynamical optical tweezers, where each one of them is generated with an independent linear polarization state with arbitrary orientation. This also allows an independent simultaneous polarization-rotation control. The laser beam, both for generating multiple traps and polarization control, has been modulated using a single reflective nematic liquid crystal with parallel alignment. We present experimental results of controlled displacement, orientation and rotation of birefringent particles. In addition, a simple method for estimating and canceling out the primary astigmatism present in the system is presented.
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| 2. |
- Ballantyne, Kaye N., et al.
(författare)
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Toward Male Individualization with Rapidly Mutating Y-Chromosomal Short Tandem Repeats
- 2014
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Ingår i: Human Mutation. - : John Wiley & Sons. - 1059-7794 .- 1098-1004. ; 35:8, s. 1021-1032
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Tidskriftsartikel (refereegranskat)abstract
- Relevant for various areas of human genetics, Y-chromosomal short tandem repeats (Y-STRs) are commonly used for testing close paternal relationships among individuals and populations, and for male lineage identification. However, even the widely used 17-loci Yfiler set cannot resolve individuals and populations completely. Here, 52 centers generated quality-controlled data of 13 rapidly mutating (RM) Y-STRs in 14,644 related and unrelated males from 111 worldwide populations. Strikingly, greater than99% of the 12,272 unrelated males were completely individualized. Haplotype diversity was extremely high (global: 0.9999985, regional: 0.99836-0.9999988). Haplotype sharing between populations was almost absent except for six (0.05%) of the 12,156 haplotypes. Haplotype sharing within populations was generally rare (0.8% nonunique haplotypes), significantly lower in urban (0.9%) than rural (2.1%) and highest in endogamous groups (14.3%). Analysis of molecular variance revealed 99.98% of variation within populations, 0.018% among populations within groups, and 0.002% among groups. Of the 2,372 newly and 156 previously typed male relative pairs, 29% were differentiated including 27% of the 2,378 father-son pairs. Relative to Yfiler, haplotype diversity was increased in 86% of the populations tested and overall male relative differentiation was raised by 23.5%. Our study demonstrates the value of RMY-STRs in identifying and separating unrelated and related males and provides a reference database.
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| 3. |
- Carrasco, Cristhian, et al.
(författare)
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Arabinosylated phenolics obtained from SO2-steam-pretreated sugarcane bagasse
- 2012
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Ingår i: Journal of Chemical Technology and Biotechnology. - : Wiley. - 0268-2575. ; 87:12, s. 1723-1726
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Tidskriftsartikel (refereegranskat)abstract
- A pentose-rich hydrolysate fraction obtained by extraction of steam-pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO2 (w/w) at 190 degrees C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5-O-(trans-feruloyl)-L-Arabinofuranose and 5-O-(trans-coumaroyl)-L-Arabinofuranose, together with p-coumaric acid and small amounts of more common free phenolics such as p-hydroxybenzaldehyde, p-hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed-phase high-performance liquid chromatography. The findings show that SO2 steam explosion opened up new degradation pathways during lignin degradation. Copyright (c) 2012 Society of Chemical Industry
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| 4. |
- Carrasco, Cristhian, et al.
(författare)
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Steam pretreatment and fermentation of the straw material "Paja Brava" using simultaneous saccharification and co-fermentation.
- 2011
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Ingår i: Journal of Bioscience and Bioengineering. - : Elsevier BV. - 1347-4421 .- 1389-1723. ; 111, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- Pretreatment, enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) of the South American straw material Paja Brava were investigated. Suitable process conditions for an SO(2)-catalyzed steam pretreatment of the material were determined and assessed by enzymatic digestibility of obtained fiber slurries for 72h at a water insoluble solids (WIS) content of 2%. The best pretreatment conditions obtained (200°C, 5min holding time and 2.5% SO(2)) gave an overall glucose yield following enzymatic hydrolysis of more than 90%, and a xylose yield of about 70%. Simultaneous saccharification and co-fermentation of glucose and xylose (SSCF) of the pretreated material using the xylose-fermenting strain Saccharomyces cerevisiae TMB3400 was examined at WIS contents between 5% and 10%. In agreement with previous studies on other materials, the overall ethanol yield and also the xylose conversion decreased somewhat with increasing WIS content in the SSCF. In batch SSCF, the xylose conversion obtained was almost 100% at 5% WIS content, but decreased to 69% at 10% WIS. The highest ethanol concentration obtained for a WIS content of 10% was about 40g/L, corresponding to a yield of 0.41g/g in a fed-batch SSCF. The Paja Brava material has previously been found difficult to hydrolyze in a dilute-acid process. However, the SSCF results obtained here show that similar sugar yields and fermentation performance can be expected from Paja Brava as from materials such as wheat straw, corn stover or sugarcane bagasse.
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| 5. |
- Escobar, Zilma, et al.
(författare)
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Synthesis of poinsettifolin A
- 2014
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 70:47, s. 9052-9056
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis of poinsettifolin A (1), a prenylated flavonol isolated from Dorstenia poinsettifolia, is described. Two routes starting from quercetin were explored, and 1 could be prepared if a prenyl group first was incorporated at C-6 of the protected quercetin followed by a condensation with citral at C-8. The key synthetic steps are a Mitsunobu reaction, an europium (III)-catalysed Claisen rearrangement coupled with cross-metathesis, and a benzopyran-forming geranylation. The two geranylated 3,5,3',4'-tetrahydroxyflavonols prepared, 1 and 3, were assayed for antileishmanial activity against Leishmania amazonensis and Leishmania braziliensis, and found to be active. Compound 3 showed cytotoxic activity against leukaemia and lung cancer cells while 1 lacked cytotoxicity. (C) 2014 Elsevier Ltd. All rights reserved.
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| 6. |
- Etcheverry, Sebastián, et al.
(författare)
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Real-time study of shape and thermal fluctuations in the echinocyte transformation of human erythrocytes using defocusing microscopy
- 2012
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 17:10, s. 106013-
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Tidskriftsartikel (refereegranskat)abstract
- We present a real-time method to measure the amplitude of thermal fluctuations in biological membranes by means of a new treatment of the defocusing microscopy (DM) optical technique. This approach was also applied to study the deformation of human erythrocytes to its echinocyte structure. This was carried out by making three-dimensional shape reconstructions of the cell and measuring the thermal fluctuations of its membrane, as the cell is exposed to the anti-inflammatory drug naproxen and as it recovers its original shape, when it is subsequently cleansed of the drug. The results showed biomechanical changes in the membrane even at low naproxen concentration (0.2 mM). Also, we found that when the cell recovered its original shape, the membrane properties were different compared to the nondrugged initial erythrocyte, indicating that the drug administration-recovery process is not completely reversible.
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| 7. |
- Guzmán, Daniel, et al.
(författare)
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Preparation of hydrophilic poly(3-hydroxybutyrate) macroporous scaffolds through enzyme-mediated modifications
- 2011
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Ingår i: Journal of Bioactive and Compatible Polymers. - : SAGE Publications. - 0883-9115 .- 1530-8030. ; 26:5, s. 452-463
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Tidskriftsartikel (refereegranskat)abstract
- Scaffolds made from poly(3-hydroxybutyrate) were prepared by thermally induced phase separation from solutions in dioxane at temperatures above (23 degrees C) or below the freezing point of the solvent. At 23 degrees C, gelation occured with nano-fibrous network formation. The scaffolds prepared at -12 degrees C and -25 degrees C exhibited a highly porous morphology, with pores in the range of 3-25 mu m, caused by freezing of dioxane. The macroporous scaffolds, prepared at -12 degrees C, were treated with lipase to generate functional groups to which gelatin and glucosamine, respectively, were chemically coupled. The modified scaffolds had lower molecular weight, higher water content, lower melting temperature, and enthalpy. Cultivation of human embryonic fibroblasts on the macroporous scaffolds confirmed that the cells proliferated and adhered to the materials.
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| 8. |
- Redwan, Itedale Namro, 1981, et al.
(författare)
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Towards the development of chromone-based MEK1/2 modulators
- 2014
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Ingår i: European Journal of Medicinal Chemistry. - : Elsevier BV. - 0223-5234. ; 85, s. 127-138
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition or allosteric modulation of mitogen-activated protein kinase kinases MEK1 and MEK2 (MEK1/2) represent a promising strategy for the discovery of new specific anticancer agents. In this paper, structure-based design, beginning from the lead compound PD98059, was used to study potential structural modifications on the chromone structure in order to obtain highly potent derivatives that target the allosteric pocket in MEK1. Subsequently, a small series of PD98059 analogs were synthesized to provide a first generation of chromone-based derivatives that inhibit the activation of MEK1 with IC50 values as low as 30 nM in vitro. Complementary cellular studies also showed that two of the compounds in the series inhibit the activity of MEK1/2 with IC50 values in the nanomolar range (73-97 nM). In addition, compounds in this series were found to inhibit the proliferation of a small panel of human cancer cell lines.
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| 9. |
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