(E)-2,3-Bis[(E)-benzyl­idene­amino]­but-2-enedinitrile

The asymmetric unit of the title compound, C18H12N4, consists of a half-mol­ecule, where the two halves of the mol­ecule are related by inversion symmetry. The mol­ecule is effectively planar, with the largest deviation from the 22-atom mean plane, measuring 0.024 (2) Å, exhibited by the ortho-C atom of the phenyl ring. The crystal structure exhibits π-stacking, with an inter­planar spacing of 3.431 (3) Å

2-(4-Chloro­phen­yl)naphtho­[1,8-de][1,3,2]diaza­borinane

The title compound, C16H12BClN2, is one in a series of diaza­borinanes, derived from 1,8-diaminona­phthalene, featuring substitution at the 1, 2 and 3 positions in the nitro­gen-boron heterocycle. The structure deviates from planarity, the torsion angle subtended by the p-chloro­phenyl ring relative to the nitro­gen–boron heterocycle being −44-.3(3)°. The mol­ecules form infinite chains with strong inter­actions between the vacant pz orbital of the B atom and the π-system of an adjacent mol­ecule. The distance between the B atom and the 10-atom centroid of an adjacent naphthalene ring is 3.381 (4) Å. One N-H H atom is weakly hydrogen bonded to the Cl atom of an adjacent mol­ecule. This combination of inter­molecular inter­actions leads to the formation of an infinite two-dimensional network perpendic­ular to the c axis

2-Phenyl­naphtho­[1,8-de][1,3,2]diaza­borinane

The title compound, C16H13BN2, is one compound in a series of diaza­borinanes featuring substitution at the 1, 2 and 3 positions in the nitro­gen–boron heterocycle. The title compound is slightly distorted from planarity, with a dihedral angle of 9.0 (5)° between the mean planes of the naphthalene system and the benzene ring. The m-carbon atom of the benzene ring exhibits the greatest deviation of 0.164 (2) Å from the 19-atom mean plane defined by all non-H atoms. The two N—B—C—C torsion angles are 6.0 (3) and 5.6 (3)°. In the crystal, mol­ecules are linked by π–π inter­actions into columns, with a distance of 3.92 (3) Å between the naphthalene ring centroids. Adjacent π-stacked columns, co-linear with the b-axis, are linked by C—H⋯π inter­actions

2-[4-(Methyl­sulfan­yl)phen­yl]naphtho[1,8-de][1,3,2]diaza­borinane

The title compound, C17H15BN2S, is one member in a series of diaza­borinanes featuring substitution at the 1-, 2- and 3-positions in the nitro­gen–boron heterocycle. The dihedral angle between the mean planes of the naphthalene and phenyl ring systems is 19.86 (6)°. In the crystal structure, two C—H⋯π inter­actions link the mol­ecules into sheets which lie parallel to the bc plane. There is a π–π inter­action between each pair of centrosymmetrically related sheets [centroid–centroid distance = 3.5922 (8) Å]

1-(5,7-Dihy­droxy-2,2-dimethylchroman-6-yl)ethanone

In the title mol­ecule, C13H16O4, the pyran ring is in a half-chair conformation. There is an intra­molecular hydrogen bond involving the ketone O atom and an H atom of a phenol group which forms an S(6) ring. The ketone O atom is also involved in an inter­molecular hydrogen bond with a different phenolic H atom of a symmetry-related mol­ecule, forming C(6) chains along the c-axis direction

1,4-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)­oxy]butane

The title compound, C34H28N6O2, has an inversion centre located at the mid-point of the central C—C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Å above the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1)°, repectively. In the crystal, weak C—H⋯N inter­actions link the mol­ecules into infinite chains parallel to the a axis

LDHB contributes to the regulation of lactate levels and basal insulin secretion in human pancreatic β cells

Using 13C6 glucose labeling coupled to gas chromatography-mass spectrometry and 2D 1H-13C heteronuclear single quantum coherence NMR spectroscopy, we have obtained a comparative high-resolution map of glucose fate underpinning β cell function. In both mouse and human islets, the contribution of glucose to the tricarboxylic acid (TCA) cycle is similar. Pyruvate fueling of the TCA cycle is primarily mediated by the activity of pyruvate dehydrogenase, with lower flux through pyruvate carboxylase. While the conversion of pyruvate to lactate by lactate dehydrogenase (LDH) can be detected in islets of both species, lactate accumulation is 6-fold higher in human islets. Human islets express LDH, with low-moderate LDHA expression and β cell-specific LDHB expression. LDHB inhibition amplifies LDHA-dependent lactate generation in mouse and human β cells and increases basal insulin release. Lastly, cis-instrument Mendelian randomization shows that low LDHB expression levels correlate with elevated fasting insulin in humans. Thus, LDHB limits lactate generation in β cells to maintain appropriate insulin release.</p

Dynamics of self-threading ring polymers in a gel

We study of the dynamics of ring polymers confined to diffuse in a background gel at low concentrations. We do this in order to probe the inter-play between topology and dynamics in ring polymers. We develop an algorithm that takes into account the possibility that the rings hinder their own motion by passing through themselves, i.e. "self-threading". Our results suggest that the number of self-threadings scales extensively with the length of the rings and that this is substantially independent of the details of the model. The slowing down of the rings' dynamics is found to be related to the fraction of segments that can contribute to the motion. Our results give a novel perspective on the motion of ring polymers in gel, for which a complete theory is still lacking, and may help us to understand the irreversible trapping of ring polymers in gel electrophoresis experiments.Comment: 11 pages,14 figures, Soft Matter 201

Evaluating the use of testate amoeba for palaeohydrological reconstruction in permafrost peatlands

The melting of high-latitude permafrost peatlands is a major concern due to a potential positive feedback on global climate change. We examine the ecology of testate amoebae in permafrost peatlands, based on sites in Sweden (~ 200 km north of the Arctic Circle). Multivariate statistical analysis confirms that water-table depth and moisture content are the dominant controls on the distribution of testate amoebae, corroborating the results from studies in mid-latitude peatlands. We present a new testate amoeba-based water table transfer function and thoroughly test it for the effects of spatial autocorrelation, clustered sampling design and uneven sampling gradients. We find that the transfer function has good predictive power; the best-performing model is based on tolerance-downweighted weighted averaging with inverse deshrinking (performance statistics with leave-one-out cross validation: R2 = 0.87, RMSEP = 5.25 cm). The new transfer function was applied to a short core from Stordalen mire, and reveals a major shift in peatland ecohydrology coincident with the onset of the Little Ice Age (c. AD 1400). We also applied the model to an independent contemporary dataset from Stordalen and find that it outperforms predictions based on other published transfer functions. The new transfer function will enable palaeohydrological reconstruction from permafrost peatlands in Northern Europe, thereby permitting greatly improved understanding of the long-term ecohydrological dynamics of these important carbon stores as well as their responses to recent climate change

2-(3-Methoxyphenyl)-1,3-dihydro-1,3,2-benzodiazaborole

The title compound, C13H13BN2O, is one in a series of 1,3,2-benzodiazaboroles featuring a 2-methoxyphenyl substitution at the 2-position in the nitrogen&amp;#8211;boron heterocyle. The dihedral angle between the mean planes of the benzodiazaborole and 2-methoxyphenyl ring systems is 21.5&amp;#8197;(1)&amp;#176;. There is an intermolecular hydrogen bond between one of the NH groups and the methoxy O atom. This hydrogen bond leads to an infinite hydrogen-bonded chain colinear with the a axis