Magnetic Frustration in a Mn Honeycomb Lattice Induced by Mn-O-O-Mn Pathways

We investigated the electronic structure of layered Mn oxide Bi3Mn4O12(NO3) with a Mn honeycomb lattice by x-ray absorption spectroscopy. The valence of Mn was determined to be 4+ with a small charge-transfer energy. We estimated the values of superexchange interactions up to the fourth nearest neighbors (J1, J2, J3, and J4) by unrestricted Hartree-Fock calculations and a perturbation method. We found that the absolute values of J1 through J4 are similar with positive (antiferromagnetic) J1 and J4, and negative (ferromagnetic) J2 and J3, due to Mn-O-O-Mn pathways activated by the smallness of charge-transfer energy. The negative J3 provides magnetic frustration in the honeycomb lattice to prevent long-range ordering.Comment: 4 pages, 3 figure

Human-iPSC-Derived Cardiac Stromal Cells Enhance Maturation in 3D Cardiac Microtissues and Reveal Non-cardiomyocyte Contributions to Heart Disease

Cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) are functionally immature, but this is improved by incorporation into engineered tissues or forced contraction. Here, we showed that tri-cellular combinations of hiPSC-derived CMs, cardiac fibroblasts (CFs), and cardiac endothelial cells also enhance maturation in easily constructed, scaffold-free, three-dimensional microtissues (MTs). hiPSC-CMs in MTs with CFs showed improved sarcomeric structures with T-tubules, enhanced contractility, and mitochondrial respiration and were electrophysiologically more mature than MTs without CFs. Interactions mediating maturation included coupling between hiPSC-CMs and CFs through connexin 43 (CX43) gap junctions and increased intracellular cyclic AMP (cAMP). Scaled production of thousands of hiPSC-MTs was highly reproducible across lines and differentiated cell batches. MTs containing healthy-control hiPSC-CMs but hiPSC-CFs from patients with arrhythmogenic cardiomyopathy strikingly recapitulated features of the disease. Our MT model is thus a simple and versatile platform for modeling multicellular cardiac diseases that will facilitate industry and academic engagement in high-throughput molecular screening

Performance of nitrogen fertilised temperate grasses and temperate grass-clover mixtures in coastal south-east Queensland

Dry matter production of nitrogen fertilised temperate grasses, including ryegrasses (Lolium spp.) and oats (Avena strigosa cv. Saia), was compared at two planting rates. Kangaroo Valley ryegrass (L. perenne) was also grown without nitrogen and in mixtures with various clovers (Trifolium spp.). The experiments were conducted at four sites, two raingrown and two irrigated, in coastal south-east Queensland from 1972 to 1975

De stijging van de waterspiegel nabij Almere in de periode 5300-2300 v. Chr

Op basis van 14C-ouderdomsbepalingen aan basisveenmonsters is een reconstructie gemaakt van de stijging van de waterspiegel in de omgeving van Almere in de periode 5300-2300 v.Chr. Een geologisch en bodemkundig onderzoek door middel van grondboringen ging vooraf aan het verzamelen van de veenmonsters. De samenstelling van het basisveen is uitvoerig paleo-ecologisch onderzocht. De dateringsgegevens zijn uitgezet in tijd-dieptediagrammen en er zijn curven getrokken die de ontwikkeling van de waterstand in de loop van de tijd weergeven. Vervolgens is een vergelijking gemaakt met de resultaten van soortgelijke studies die elders in Flevoland zijn uitgevoerd. Ook is een vergelijking gemaakt met de ontwikkeling van de zeespiegel. Het onderzoek kan bijdragen aan een betere inschatting van de bewoningsmogelijkheden van het studiegebied in de Midden- en Late Steentijd, hetgeen relevant is voor onderzoek naar archeologische waarden

De stijging van de waterspiegel nabij Almere in de periode 5300-2300 v. Chr

Op basis van 14C-ouderdomsbepalingen aan basisveenmonsters is een reconstructie gemaakt van de stijging van de waterspiegel in de omgeving van Almere in de periode 5300-2300 v.Chr. Een geologisch en bodemkundig onderzoek door middel van grondboringen ging vooraf aan het verzamelen van de veenmonsters. De samenstelling van het basisveen is uitvoerig paleo-ecologisch onderzocht. De dateringsgegevens zijn uitgezet in tijd-dieptediagrammen en er zijn curven getrokken die de ontwikkeling van de waterstand in de loop van de tijd weergeven. Vervolgens is een vergelijking gemaakt met de resultaten van soortgelijke studies die elders in Flevoland zijn uitgevoerd. Ook is een vergelijking gemaakt met de ontwikkeling van de zeespiegel. Het onderzoek kan bijdragen aan een betere inschatting van de bewoningsmogelijkheden van het studiegebied in de Midden- en Late Steentijd, hetgeen relevant is voor onderzoek naar archeologische waarden

Relative water-level rise in the Flevo lagoon (The Netherlands), 5300-2000 cal. yr BC: an evaluation of new and existing basal peat time-depth data

In this study, all available 14C dates from the base of basal peat overlying the top of compaction-free Pleistocene sand in the former Flevo lagoon were evaluated in order to reconstruct water-level rise for the period 5300-2000 cal. yr BCThe rise of Holocene (ground)water level as a function of relative sea-level rise has been extensively investigated in the western Netherlands, whereas few studies focused on the Flevo lagoon in the central Netherlands. In this study, all available C-14 dates from the base of basal peat overlying the top of compaction-free Pleistocene sand in the former Flevo lagoon were evaluated in order to reconstruct water-level rise for the period 5300-2000 cal. yr BC. The present basal peat C-14 data set from Flevoland consists of two subsets: (1) the largely new Almere data (41 dates) representing the southern part of the former Flevo lagoon, with 26 dates especially carried out for this study, and (2) the existing Schokland data (21 dates) representing the eastern part of the lagoon. The Schokland area is located about 50 km from the Almere area. The quality of all basal peat time-depth data was palaeo-ecologically and geologically evaluated, all C-14 dates were calibrated to the same standards, and error margins of age and altitude determination were estimated. After plotting the data as error boxes in time-depth graphs, lower limit curves for water-level rise were constructed for both data sets. Comparison with the mean sea-level curve for The Netherlands (Van de Plassche, 1982) suggests that water-level rise in the Almere area between 5300 and 2000 cal. yr BC corresponded closely to the rise in mean sea level. The same holds for the Schokland area for the period 5000-4200 cal. yr BC. For the period 4200-2000 cal. yr BC, however, the Schokland data suggest water-level rise to have been slower than mean sea-level rise, leading to local water levels apparently below mean sea level, which is virtually impossible. Hypothetical explanations for this discrepancy include: errors and uncertainties in mean sea-level and local water-level reconstruction, basin subsidence and temporal differences in intra-coastal tidal damping. The presently available data are inconclusive at this point and Holocene water-level rise in the Flevo lagoon awaits further investigations

Relative water-level rise in the Flevo lagoon (The Netherlands), 5300-2000 cal. yr BC: an evaluation of new and existing basal peat time-depth data

In this study, all available 14C dates from the base of basal peat overlying the top of compaction-free Pleistocene sand in the former Flevo lagoon were evaluated in order to reconstruct water-level rise for the period 5300-2000 cal. yr BCThe rise of Holocene (ground)water level as a function of relative sea-level rise has been extensively investigated in the western Netherlands, whereas few studies focused on the Flevo lagoon in the central Netherlands. In this study, all available C-14 dates from the base of basal peat overlying the top of compaction-free Pleistocene sand in the former Flevo lagoon were evaluated in order to reconstruct water-level rise for the period 5300-2000 cal. yr BC. The present basal peat C-14 data set from Flevoland consists of two subsets: (1) the largely new Almere data (41 dates) representing the southern part of the former Flevo lagoon, with 26 dates especially carried out for this study, and (2) the existing Schokland data (21 dates) representing the eastern part of the lagoon. The Schokland area is located about 50 km from the Almere area. The quality of all basal peat time-depth data was palaeo-ecologically and geologically evaluated, all C-14 dates were calibrated to the same standards, and error margins of age and altitude determination were estimated. After plotting the data as error boxes in time-depth graphs, lower limit curves for water-level rise were constructed for both data sets. Comparison with the mean sea-level curve for The Netherlands (Van de Plassche, 1982) suggests that water-level rise in the Almere area between 5300 and 2000 cal. yr BC corresponded closely to the rise in mean sea level. The same holds for the Schokland area for the period 5000-4200 cal. yr BC. For the period 4200-2000 cal. yr BC, however, the Schokland data suggest water-level rise to have been slower than mean sea-level rise, leading to local water levels apparently below mean sea level, which is virtually impossible. Hypothetical explanations for this discrepancy include: errors and uncertainties in mean sea-level and local water-level reconstruction, basin subsidence and temporal differences in intra-coastal tidal damping. The presently available data are inconclusive at this point and Holocene water-level rise in the Flevo lagoon awaits further investigations