| 1. |
- Allentoft, Morten E., et al.
(författare)
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100 ancient genomes show repeated population turnovers in Neolithic Denmark
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 625, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- Major migration events in Holocene Eurasia have been characterized genetically at broad regional scales1–4. However, insights into the population dynamics in the contact zones are hampered by a lack of ancient genomic data sampled at high spatiotemporal resolution5–7. Here, to address this, we analysed shotgun-sequenced genomes from 100 skeletons spanning 7,300 years of the Mesolithic period, Neolithic period and Early Bronze Age in Denmark and integrated these with proxies for diet (13C and 15N content), mobility (87Sr/86Sr ratio) and vegetation cover (pollen). We observe that Danish Mesolithic individuals of the Maglemose, Kongemose and Ertebølle cultures form a distinct genetic cluster related to other Western European hunter-gatherers. Despite shifts in material culture they displayed genetic homogeneity from around 10,500 to 5,900 calibrated years before present, when Neolithic farmers with Anatolian-derived ancestry arrived. Although the Neolithic transition was delayed by more than a millennium relative to Central Europe, it was very abrupt and resulted in a population turnover with limited genetic contribution from local hunter-gatherers. The succeeding Neolithic population, associated with the Funnel Beaker culture, persisted for only about 1,000 years before immigrants with eastern Steppe-derived ancestry arrived. This second and equally rapid population replacement gave rise to the Single Grave culture with an ancestry profile more similar to present-day Danes. In our multiproxy dataset, these major demographic events are manifested as parallel shifts in genotype, phenotype, diet and land use.
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| 2. |
- Allentoft, Morten E., et al.
(författare)
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Population genomics of post-glacial western Eurasia
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 625:7994, s. 301-311
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Tidskriftsartikel (refereegranskat)abstract
- Western Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.
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| 3. |
- Gosalawit-Utke, Rapee, et al.
(författare)
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Nanoconfined 2LiBH(4)-MgH2 Prepared by Direct Melt Infiltration into Nanoporous Materials
- 2011
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:21, s. 10903-10910
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Tidskriftsartikel (refereegranskat)abstract
- Nanoconfined 2LiBH(4)-MgH2 is prepared by direct melt infiltration of bulk 2LiBH(4)-MgH2 into an inert nanoporous resorcinol-formaldehyde carbon aerogel scaffold material. Scanning electron microscopy (SEM) micrographs and energy dispersive X-ray spectroscopy (EDS) mapping reveal homogeneous dispersion of Mg (from MgH2) and B (from LiBH4) inside the carbon aerogel scaffold. Moreover, nanoconfinement of LiBH4 in the carbon aerogel scaffold is confirmed by differential scanning calorimetry (DSC). The hydrogen desorption kinetics of the nanoconfined 2LiBH(4)-MgH2 is significantly improved as compared to bulk 2LiBH(4)-MgH2. For instance, the nanoconfined 2LiBH(4)-MgH2 releases 90% of the total hydrogen storage capacity within 90 mm, whereas the bulk material releases only 34% (at T = 425 degrees C and p(H-2) = 3.4 bar). A reversible gravimetric hydrogen storage capacity of 10.8 wt % H-2, calculated with respect to the metal hydride content, is preserved over four hydrogen release and uptake cycles.
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| 4. |
- Alcantara, K. Suarez, et al.
(författare)
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3CaH(2)+4MgB(2) + CaF2 Reactive Hydride Composite as a Potential Hydrogen Storage Material: Hydrogenation and Dehydrogenation Pathway
- 2012
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:12, s. 7207-7212
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Tidskriftsartikel (refereegranskat)abstract
- A reactive hydride composite (RHC) with initial composition 3CaH(2) + 4MgB(2) + CaF2 was studied by in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and X-ray absorption near edge structure (XANES) at the B K-edge and at the Ca K-edge. The hydrogenation reaction proceeds by an unknown intermediate. No evidence of intermediates was observed during the dehydrogenation reaction. B and Ca K-edge XANES results hint to a closed interaction of CaF2 and Ca(BH4)(2). The main function of CaF2 in the 3CaH(2) + 4MgB(2) + CaF2 RHC is as a dopant for the hydrogenation and dehydrogenation reactions.
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| 5. |
- Barkhordarian, Gagik, et al.
(författare)
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Formation of Ca(BH4)(2) from hydrogenation of CaH2+MgB2 composite
- 2008
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:7, s. 2743-2749
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogenation of the CaH2+MgB2 Composite and the dehydrogenation of the resulting products are investigated in detail by in situ time-resolved synchrotron radiation powder X-ray diffraction, high-pressure differential scanning calorimetry, infrared, and thermovolumetric measurements. It is demonstrated that a Ca(BH4)(2)+MgH2 composite is formed by hydrogenating a CaH2+MgB2 composite, at 350 degrees C and 140 bar of hydrogen. Two phases of Ca(BH4)(2) were characterized: alpha- and beta-Ca(BH4)(2). alpha-Ca(BH4)(2) transforms to beta-Ca(BH4)(2) at about 130 degrees C. Under the conditions used in the present study, beta-Ca(BH4)(2) decomposes first to CaH2, Ca3Mg4H14, Mg, B (or MgB2 depending on experimental conditions), and hydrogen at 360 degrees C, before complete decomposition to CaH2, Mg, B (or MgB2), and hydrogen at 400 degrees C. During hydrogenation under 140 bar of hydrogen, beta-Ca(BH4)(2) is formed at 250 degrees C, and alpha-Ca(BH4)(2) is formed when the sample is cooled to less than 130 degrees C. Ti isopropoxide improves the kinetics of the reactions, during both hydrogenation and dehydrogenation. The dehydrogenation temperature decreases to 250 degrees C, with 1 wt % of this additive, and hydrogenation starts already at 200 degrees C. We propose that the improved kinetics of the above reactions with MgB2 (compared to pure boron) can be explained by the different boron bonding within the crystal structure of MgB2 and pure boron.
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| 6. |
- Boesenberg, Ulrike, et al.
(författare)
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Hydrogen sorption properties of MgH2-LiBH4 composites
- 2007
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Ingår i: Acta Materialia. - : Elsevier BV. - 1873-2453 .- 1359-6454. ; 55:11, s. 3951-3958
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analysis of the reaction mechanism of the reactive hydride composite (RHC) MgH2 + 2LiBH(4) <-> MgB2 + 2LiH + 4H(2) was performed using high-pressure differential scanning calorimetry (HP-DSC) measurements and in situ synchrotron powder X-ray diffraction (XRD) measurements along with kinetic investigations using a Sievert-type apparatus. For the desorption the following two-step reaction has been observed: MgH2 + 2LiBH(4) <-> Mg + 2LiBH(4) + H-2 <-> MgB2 + 2LiH + 4H(2). However, this reaction is kinetically restricted and proceeds only at elevated temperatures. In contrast to the desorption reaction, LiBH4 and MgH2 are found to form simultaneously under fairly moderate conditions of 50 bar hydrogen pressure in the temperature range of 250-300 degrees C. As found in pure light metal hydrides, significant improvement of sorption kinetics is possible if suitable additives are used. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 7. |
- Gosalawit-Utke, Rapee, et al.
(författare)
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Ca(BH4)(2)-MgF2 Reversible Hydrogen Storage: Reaction Mechanisms and Kinetic Properties
- 2011
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:9, s. 3762-3768
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Tidskriftsartikel (refereegranskat)abstract
- A composite of Ca(BH4)(2)-MgF2 is proposed as a reversible hydrogen storage system. The dehydrogenation and rehydrogenation reaction mechanisms are investigated by in situ time-resolved synchrotron radiation powder X-ray diffraction (SR-PXD) and Raman spectroscopy. The formation of an intermediate phase (CaF2-xHx) is observed during rehydrogenation. The hydrogen content of 4.3 wt % is obtained within 4 h during the first dehydrogenation at isothermal and isobaric conditions of 330 degrees C and 0.5 bar H-2, respectively. The cycling efficiency is evaluated by three release and uptake cycles together with absorbed hydrogen content in the range 5.1-5.8 wt % after 2.5 h (T = 330 degrees C and p(H-2) = 130 bar). The kinetic properties on the basis of hydrogen absorption are comparable for all cycles. As compared to pure Ca(BH4)(2) and Ca(BH4)(2)-MgH2 composite, Ca(BH4)(2)-MgF2 composite reveals the kinetic destabilization and the reproducibility of hydrogen storage capacities during cycling, respectively.
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| 8. |
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| 9. |
- Martinez-Ramirez, Daniel, et al.
(författare)
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Efficacy and Safety of Deep Brain Stimulation in Tourette Syndrome : The International Tourette Syndrome Deep Brain Stimulation Public Database and Registry
- 2018
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Ingår i: JAMA Neurology. - : American Medical Association. - 2168-6149 .- 2168-6157. ; 75:3, s. 353-359
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Collective evidence has strongly suggested that deep brain stimulation (DBS) is a promising therapy for Tourette syndrome.OBJECTIVE To assess the efficacy and safety of DBS in a multinational cohort of patients with Tourette syndrome.DESIGN, SETTING, AND PARTICIPANTS The prospective International Deep Brain Stimulation Database and Registry included 185 patients with medically refractory Tourette syndrome who underwent DBS implantation from January 1, 2012, to December 31, 2016, at 31 institutions in 10 countries worldwide.EXPOSURES Patients with medically refractory symptoms received DBS implantation in the centromedian thalamic region (93 of 163 [57.1%]), the anterior globus pallidus internus (41 of 163 [25.2%]), the posterior globus pallidus internus (25 of 163 [15.3%]), and the anterior limb of the internal capsule (4 of 163 [2.5%]).MAIN OUTCOMES AND MEASURES Scores on the Yale Global Tic Severity Scale and adverse events.RESULTS The International Deep Brain Stimulation Database and Registry enrolled 185 patients (of 171 with available data, 37 females and 134 males; mean [SD] age at surgery, 29.1 [10.8] years [range, 13-58 years]). Symptoms of obsessive-compulsive disorder were present in 97 of 151 patients (64.2%) and 32 of 148 (21.6%) had a history of self-injurious behavior. The mean (SD) total Yale Global Tic Severity Scale score improved from 75.01 (18.36) at baseline to 41.19 (20.00) at 1 year after DBS implantation (P<.001). The mean (SD) motor tic subscore improved from 21.00 (3.72) at baseline to 12.91 (5.78) after 1 year (P <.001), and the mean (SD) phonic tic subscore improved from 16.82 (6.56) at baseline to 9.63 (6.99) at 1 year (P <.001). The overall adverse event rate was 35.4%(56 of 158 patients), with intracranial hemorrhage occurring in 2 patients (1.3%), infection in 4 patients with 5 events (3.2%), and lead explantation in 1 patient (0.6%). The most common stimulation-induced adverse effects were dysarthria (10 [6.3%]) and paresthesia (13 [8.2%]).CONCLUSIONS AND RELEVANCE Deep brain stimulationwas associated with symptomatic improvement in patients with Tourette syndrome but also with important adverse events. A publicly available website on outcomes of DBS in patients with Tourette syndrome has been provided.
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| 10. |
- Medema, M. H., et al.
(författare)
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Minimum Information about a Biosynthetic Gene cluster
- 2015
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Ingår i: Nature Chemical Biology. - : Springer Science and Business Media LLC. - 1552-4450 .- 1552-4469. ; 11:9, s. 625-631
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Forskningsöversikt (refereegranskat)abstract
- A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.
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| 11. |
- Minella, Christian Bonatto, et al.
(författare)
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Effect of Transition Metal Fluorides on the Sorption Properties and Reversible Formation of Ca(BH4)(2)
- 2011
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:5, s. 2497-2504
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Tidskriftsartikel (refereegranskat)abstract
- Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 kJ mol(-1)H(2), Ca(BH4)(2) is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)(2) was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by B-11{H-1} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H-2 pressure and 350 degrees C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, B-11{H-1} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)(2) samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)(2).
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| 12. |
- Pistidda, C., et al.
(författare)
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First Direct Study of the Ammonolysis Reaction in the Most Common Alkaline and Alkaline Earth Metal Hydrides by in Situ SR-PXD
- 2015
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:2, s. 934-943
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first in situ synchrotron radiation powder X-ray diffraction study (SR-PXD) of the ammonolysis reaction of selected alkaline and alkaline earth metal hydrides (i.e., LiH, NaH, KH, MgH2, and CaH2). The investigation was performed using an in situ SR-PXD pressure cell at an initial NH3 pressure of 6.5 bar in a range of temperature between room temperature (RT) and 350 degrees C. The results of this work give new important insights into the formation of metal amides and imides starting from the corresponding metal hydrides. LiH was observed to react with NH3 to form LiNH2 already at RT, and then it decomposes into Li2NH at 310 degrees C through the formation of nonstoichiometric intermediates of the Li1+-xNH2-x form. The formation of NaNH2 takes place nearly at RT (28 degrees C), and it melts at 180 degrees C. As for LiH, KH reacts with NH3 at RT to surprisingly form, what it seems to be, cubic KNH2. However, we believe this phase to be a solid solution of KH in KNH2. At high temperature, the possible formation of several solid solutions of K(NH2)(1-y)H-y with defined composition is also observed. The formation of Mg(NH2)(2) was observed to starts at around 220 degrees C, from the interaction beta-MgH2 and NH3. At 350 degrees C, when all beta-MgH2 is consumed, the formation of Mg(NH2)(2) stops and MgNH is formed by the reaction between beta-MgH2 and NH3. Our results indicate that the formation of the beta-MgH2 is a key step in the synthesis of Mg(NH2)(2) at low temperature (e.g., via ball milling technique). CaH2 was observed to react with NH3 at around 140 degrees C to form CaNH. At higher temperature the appearance of new reflections of possible Ca1+xNH phases, with the same crystalline structure of CaNH but with a smaller cell parameter was observed.
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| 13. |
- Pistidda, C., et al.
(författare)
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Hydrogen storage systems from waste Mg alloys
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 1873-2755 .- 0378-7753. ; 270, s. 554-563
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Tidskriftsartikel (refereegranskat)abstract
- The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)(2) and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH(4) + MgH2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes. (C) 2014 Elsevier B.V. All rights reserved.
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| 14. |
- Pranzas, P. Klaus, et al.
(författare)
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Characterization of Hydrogen Storage Materials and Systems with Photons and Neutrons
- 2011
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Ingår i: Advanced Engineering Materials. - : Wiley. - 1527-2648 .- 1438-1656. ; 13:8, s. 730-736
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Tidskriftsartikel (refereegranskat)abstract
- Complex hydrides are very promising candidates for future light-weight solid state hydrogen storage materials. The present work illustrates detailed characterization of such novel hydride materials on different size scales by the use of synchrotron radiation and neutrons. The comprehensive analysis of such data leads to a deep understanding of the ongoing processes and mechanisms. The reaction pathways during hydrogen desorption and absorption are identified by in situ X-ray diffraction (XRD). Function and size of additive phases are estimated using X-ray absorption spectroscopy (XAS) and anomalous small-angle X-ray scattering (ASAXS). The structure of the metal hydride matrix is characterized using (ultra) small-angle neutron scattering (SANS/USANS). The hydrogen distribution in tanks filled with metal hydride material is studied with neutron computerized tomography (NCT). The results obtained by the different analysis methods are summarized in a final structural model. The complementary information obtained by these different methods is essential for the understanding of the various sorption processes in light metal hydrides and hydrogen storage tanks.
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| 15. |
- Puszkiel, Julian, et al.
(författare)
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Hydrogen storage in Mg-LiBH4 composites catalyzed by FeF3
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 1873-2755 .- 0378-7753. ; 267, s. 799-811
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Tidskriftsartikel (refereegranskat)abstract
- Mg-10 mol% LiBH4 composite plus small amounts of FeF3 is investigated in the present work. The presence of LiBH4 during the milling process noticeably modifies the size and morphology of the Mg agglomerates, leading to faster hydrogenation and reaching almost the theoretical hydrogen capacity owing to enhanced hydrogen diffusion mechanism. However, the dehydrogenation of the system at low temperatures (<= 300 degrees C) is still slow. Thus, FeF3 addition is proposed to improve the dehydrogenation kinetic behavior. From experimental results, it is found that the presence of FeF3 results in an additional size reduction of the Mg agglomerates between similar to 10 and similar to 100 mu m and the formation of stable phases such as MgF2, LiF and FeB. The FeB species might have a catalytic effect upon the MgH2 decomposition. As a further result of the FeF3 addition, the Mg-10 mol%LiBH4-5 mol% FeF3 material shows improved dehydrogenation properties: reduced dehydrogenation activation energy, faster hydrogen desorption rate and reversible hydrogen capacities of about 5 wt% at 275 degrees C. (C) 2014 Elsevier B.V. All rights reserved.
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| 16. |
- Puszkiel, Julian, et al.
(författare)
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Sorption behavior of the MgH2-Mg2FeH6 hydride storage system synthesized by mechanical milling followed by sintering
- 2013
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 38:34, s. 14618-14630
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogen sorption behavior of the Mg2FeH6-MgH2 hydride system is investigated via in-situ synchrotron and laboratory powder X-ray diffraction (SR-PXD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), particle size distribution (PSD) and volumetric techniques. The Mg2FeH6-MgH2 hydride system is obtained by mechanical milling in argon atmosphere followed by sintering at high temperature and hydrogen pressure. In-situ SR-PXD results show that upon hydriding MgH2 is a precursor for Mg2FeH6 formation and remained as hydrided phase in the obtained material. Diffusion constraints preclude the further formation of Mg2FeH6. Upon dehydriding, our results suggest that MgH2 and Mg2FeH6 decompose independently in a narrow temperature range between 275 and 300 degrees C. Moreover, the decomposition behavior of both hydrides in the Mg2FeH6-MgH2 hydride mixture is influenced by each other via dual synergetic-destabilizing effects. The final hydriding/dehydriding products and therefore the kinetic behavior of the Mg2FeH6-MgH2 hydride system exhibits a strong dependence on the temperature and pressure conditions. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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