| 1. |
- Cassimjee, Karim Engelmark, et al.
(författare)
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Streamlined Preparation of Immobilized Candida antarctica Lipase B
- 2017
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:12, s. 8674-8677
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Tidskriftsartikel (refereegranskat)abstract
- Candida antarctica lipase B (CalB) was efficiently expressed (6.2 g L-1) in Escherichia coli by utilizing an N-terminal tag cassette and the XylS/Pm expression system in a fed-batch bioreactor; subsequent direct binding to EziG from crude extracts resulted in an immobilized catalyst with superior activity to Novozym 435.
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| 2. |
- Ermolaev, Georgy A., et al.
(författare)
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Broadband optical properties of monolayer and bulk MoS 2
- 2020
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Ingår i: npj 2D Materials and Applications. - : Springer Science and Business Media LLC. - 2397-7132. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Layered semiconductors such as transition metal dichalcogenides (TMDs) offer endless possibilities for designing modern photonic and optoelectronic components. However, their optical engineering is still a challenging task owing to multiple obstacles, including the absence of a rapid, contactless, and the reliable method to obtain their dielectric function as well as to evaluate in situ the changes in optical constants and exciton binding energies. Here, we present an advanced approach based on ellipsometry measurements for retrieval of dielectric functions and the excitonic properties of both monolayer and bulk TMDs. Using this method, we conduct a detailed study of monolayer MoS2 and its bulk crystal in the broad spectral range (290–3300 nm). In the near- and mid-infrared ranges, both configurations appear to have no optical absorption and possess an extremely high dielectric permittivity making them favorable for lossless subwavelength photonics. In addition, the proposed approach opens a possibility to observe a previously unreported peak in the dielectric function of monolayer MoS2 induced by the use of perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) seeding promoters for MoS2 synthesis and thus enables its applications in chemical and biological sensing. Therefore, this technique as a whole offers a state-of-the-art metrological tool for next-generation TMD-based devices.
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| 3. |
- Kılınç, Gülşah Merve, et al.
(författare)
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Human population dynamics and Yersinia pestis in ancient northeast Asia
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- We present genome-wide data from 40 individuals dating to c.16,900 to 550 years ago in northeast Asia. We describe hitherto unknown gene flow and admixture events in the region, revealing a complex population history. While populations east of Lake Baikal remained relatively stable from the Mesolithic to the Bronze Age, those from Yakutia and west of Lake Baikal witnessed major population transformations, from the Late Upper Paleolithic to the Neolithic, and during the Bronze Age, respectively. We further locate the Asian ancestors of Paleo-Inuits, using direct genetic evidence. Last, we report the most northeastern ancient occurrence of the plague-related bacterium, Yersinia pestis. Our findings indicate the highly connected and dynamic nature of northeast Asia populations throughout the Holocene.
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| 4. |
- Kılınç, Gülşah Merve, et al.
(författare)
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Investigating Holocene human population history in North Asia using ancient mitogenomes
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Archaeogenomic studies have largely elucidated human population history in West Eurasia during the Stone Age. However, despite being a broad geographical region of significant cultural and linguistic diversity, little is known about the population history in North Asia. We present complete mitochondrial genome sequences together with stable isotope data for 41 serially sampled ancient individuals from North Asia, dated between c. 13,790 BP and c. 1,380 BP extending from the Palaeolithic to the Iron Age. Analyses of mitochondrial DNA sequences and haplogroup data of these individuals revealed the highest genetic affinity to present-day North Asian populations of the same geographical region suggesting a possible long-term maternal genetic continuity in the region. We observed a decrease in genetic diversity over time and a reduction of maternal effective population size (Ne) approximately seven thousand years before present. Coalescent simulations were consistent with genetic continuity between present day individuals and individuals dating to 7,000 BP, 4,800 BP or 3,000 BP. Meanwhile, genetic differences observed between 7,000 BP and 3,000 BP as well as between 4,800 BP and 3,000 BP were inconsistent with genetic drift alone, suggesting gene flow into the region from distant gene pools or structure within the population. These results indicate that despite some level of continuity between ancient groups and present-day populations, the region exhibits a complex demographic history during the Holocene.
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| 5. |
- Kostin, Alexander I., et al.
(författare)
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Impact of pathogen reduction methods on immunological properties of the COVID-19 convalescent plasma
- 2021
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Ingår i: Vox Sanguinis. - : Wiley. - 0042-9007 .- 1423-0410. ; 116:6, s. 665-672
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Tidskriftsartikel (refereegranskat)abstract
- Background and objectives: COVID-19 convalescent plasma is an experimental treatment against SARS-CoV-2. The aim of this study is to assess the impact of different pathogen reduction methods on the levels and virus neutralizing activity of the specific antibodies against SARS-CoV2 in convalescent plasma. Materials and methods: A total of 140 plasma doses collected by plasmapheresis from COVID-19 convalescent donors were subjected to pathogen reduction by three methods: methylene blue (M)/visible light, riboflavin (R)/UVB and amotosalen (A)/UVA. To conduct a paired comparison, individual plasma doses were divided into 2 samples that were subjected to one of these methods. The titres of SARS-CoV2 neutralizing antibodies (NtAbs) and levels of specific immunoglobulins to RBD, S- and N-proteins of SARS-CoV-2 were measured before and after pathogen reduction. Results: The methods reduced NtAbs titres differently: among units with the initial titre 80 or above, 81% of units remained unchanged and 19% decreased by one step after methylene blue; 60% were unchanged and 40% decreased by one step after amotosalen; after riboflavin 43% were unchanged and 50% (7%, respectively) had a one-step (two-step, respectively) decrease. Paired two-sample comparisons (M vs. A, M vs. R and A vs. R) revealed that the largest statistically significant decrease in quantity and activity of the specific antibodies resulted from the riboflavin treatment. Conclusion: Pathogen reduction with methylene blue or with amotosalen provides the greater likelihood of preserving the immunological properties of the COVID-19 convalescent plasma compared to riboflavin.
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| 6. |
- Kovalenko, Oleksandr O., et al.
(författare)
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Mild and Selective Et2Zn-Catalyzed Reduction of Tertiary Amides under Hydrosilylation Conditions
- 2015
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 17:3, s. 446-449
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Tidskriftsartikel (refereegranskat)abstract
- Diethylzinc (Et2Zn) can be used as an efficient and chemoselective catalyst for the reduction of tertiary amides under mild reaction conditions employing cost-effective polymeric silane (PMHS) as the hydride source. Crucial for the catalytic activity was the addition of a substoichiometric amount of lithium chloride to the reaction mixture. A series of amides containing different additional functional groups were reduced to their corresponding amines, and the products were isolated in good-to-excellent yields.
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| 7. |
- Paukov, Maksim I., et al.
(författare)
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Optoelectronic properties of nanotubes based on tungsten disulfide
- 2022
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Ingår i: 2022 IEEE Photonics Society Summer Topicals Meeting Series, SUM 2022 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Inorganic nanotubes (NT), such as WS2NT, have unique properties making them promising candidates for op-toelectronic devices. Herein, we performed optical absorption, Raman, and time-domain terahertz spectroscopy of WS2NT in addition to the microscopy measurements to reveal their optoelectronic properties.
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| 8. |
- Slagbrand, Tove, et al.
(författare)
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Transformation of Amides into Highly Functionalized Triazolines
- 2017
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 7:3, s. 1771-1775
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Tidskriftsartikel (refereegranskat)abstract
- Triazoles and triazolines are important classes of heterocyclic compounds known to exhibit biological activity. Significant focus has been given to the development of synthetic approaches for the preparation of triazoles, and they are today easily obtainable through a large variety of protocols. The number of synthetic procedures for the formation of triazolines, on the other hand, is limited and further research in this field is required. The protocol presented here gives access to a broad scope of 1,4,5-substituted 1,2,3-triazolines through a one-pot transformation of carboxamides. The two-step procedure involves a Mo(CO)6-catalyzed reduction of tertiary amides to afford the corresponding enamines, followed by in situ cycloaddition of organic azides to form triazolines. The amide reduction is chemoselective and allows for a wide variety of functional groups such as esters, ketones, aldehydes, and imines to be tolerated. Furthermore, a modification of this one-pot procedure gives access to the corresponding triazoles. The chemically stable amide functionality is demonstrated to be an efficient synthetic handle for the formation of highly substituted triazolines or triazoles.
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| 9. |
- Tinnis, Fredrik, et al.
(författare)
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Chemoselective Reduction of Tertiary Amides under Thermal Control: Formation of either Aldehydes or Amines
- 2016
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 55:14, s. 4562-4566
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Tidskriftsartikel (refereegranskat)abstract
- The chemoselective reduction of amides in the presence of other more reactive reducible functional groups is a highly challenging transformation, and successful examples thereof are most valuable in synthetic organic chemistry. Only a limited number of systems have demonstrated the chemoselective reduction of amides over ketones. Until now, the aldehyde functionality has not been shown to be compatible in any catalytic reduction protocol. Described herein is a [Mo(CO)6]-catalyzed protocol with an unprecedented chemoselectivity and allows for the reduction of amides in the presence of aldehydes and imines. Furthermore, the system proved to be tunable by variation of the temperature, which enabled for either C−O or C−N bond cleavage that ultimately led to the isolation of both amines and aldehydes, respectively, in high chemical yields.
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| 10. |
- Vereshchagin, Anatoliy A., et al.
(författare)
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Interaction of amines with electrodes modified by polymeric complexes of Ni with salen-type ligands
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 211, s. 726-734
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Tidskriftsartikel (refereegranskat)abstract
- Chemically modified electrodes based on complexes of transition metals with N, N'-ethylenebis (salicylimine) (salen) type ligands are reported to act as redox mediators due to axial coordination of exogeneous ligands to metal atom in oxidized form of complex. Thus such electrodes can be used as amperometric and voltammetric detectors of various compounds. However, effects of ligand structure and ligand-analyte specific interactions on the electrochemical response of said complexes have not been studied yet for organic analytes. In this article we demonstrate that some aromatic amines can interact with salen-type ligands by several routes, depending on the ligand and amine structure. It leads to the ligand polarization, and thus to the unique shape of voltammetric curves of chemically modified electrodes, based on polymeric salen complexes, immersed in amines solutions. Such feature allows using the electrodes as sensors for molecular recognition. The same electrodes can act as electron transfer catalysts of the amines oxidation, and may be applicable to the quantitative analysis of amines with the detection limit about 10 mu mol l(-1).
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