Poly[diaquabis­(μ4-fumarato-κ4 O 1:O 1′:O 4:O 4′)(μ4-fumarato-κ6 O 1:O 1,O 1′:O 4:O 4,O 4′)(μ2-fumaric acid-κ2 O 1:O 4)dipraseodymium(III)]

The title complex, [Pr2(C4H2O4)3(C4H4O4)(H2O)2]n, was synthesized by reaction of praseodymium(III) nitrate hexa­hydrate with fumaric acid in a water–ethanol (4:1) solution. The asymmetric unit comprises a Pr3+ cation, one and a half fumarate dianions (L 2−), one half-mol­ecule of fumaric acid (H2L) and one coordinated water mol­ecule. The carboxyl­ate groups of the fumarate dianion and fumaric acid exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups are chelating with two Pr3+ cations, and the other two O atoms each coordinate a Pr3+ cation. Each O atom of the second fumarate dianion binds to a different Pr3+ cation. The fumaric acid employs one O atom at each end to bridge two Pr3+ cations. The Pr3+ cation is coordinated in a distorted tricapped trigonal–prismatic environment by eight O atoms of fumarate dianion or fumaric acid ligands and one water O atom. The PrO9 coordination polyhedra are edge-shared through one carboxyl­ate O atom and two carboxyl­ate groups, generating infinite praseodymium–oxygen chains, which are further connected by the ligands into a three-dimensional framework. The crystal structure is stabilized by O—H⋯O hydrogen-bond inter­actions between the coordin­ated water mol­ecule and the carboxyl­ate O atoms

2-(3,3,4,4-Tetra­fluoro­pyrrolidin-1-yl)aniline

In the title fluorinated pyrrolidine derivative, C10H10F4N2, the dihedral angle between the best planes of the benzene and pyrrolidine rings is 62.6 (1)°. The crystal packing features inter­molecular N—H⋯F hydrogen bonds

Poly[[tetra­aqua-μ4-fumarato-di-μ3-fumarato-dineodymium(III)] trihydrate]

The title coordination polymer, {[Nd2(C4H2O4)3(H2O)4]·3H2O}, was synthesized by the reaction of neodymium(III) nitrate hexa­hydrate with fumaric acid in a water–methanol (7:3) solution. The asymmetric unit comprises two Nd3+ cations, three fumarate dianions (L 2−), four aqua ligands and three uncoordinated water mol­ecules. The carboxyl­ate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups chelate two Nd3+ cations, while one of the O atoms is coordinated to another Nd3+ cation. Another fumarate dianion bridges three Nd3+ cations: one of the carboxyl­ate groups chelates one Nd3+ cation, while the other carboxyl­ate group bridges two Nd3+ cations in a monodentate mode. The third fumarate dianion bridges four Nd3+ cations, where one of the carboxyl­ate groups chelates one Nd3+ cation and coordinates in a monodentate mode to a second Nd3+, while the second carboxyl­ate groups bridges two Nd3+ cations in a monodentate mode and one O atom is coordinated to one Nd3+ cation. The Nd3+ cations are in a distorted tricapped–trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water mol­ecules. The Nd3+ cations are linked by two carboxyl­ate O atoms and two carboxyl­ate groups, generating infinite Nd–O chains to form a three-dimensional framework. There are O—H⋯O and C—H⋯O hydrogen-bonding interactions between the coordin­ated and uncoordinated water mol­ecules and carboxyl­ate O atoms

A digital library for geography examination resources

We describe a Web-based application developed above a digital library of geographical resources for Singapore students preparing to take a national examination in geography. The application provides an interactive, non-sequential approach to learning that supplements textbooks.Published versio

3,3,4,4-Tetra­fluoro-1-[2-(3,3,4,4-tetra­fluoro­pyrrolidin-1-yl)phen­yl]pyrrolidine

The asymmetric unit of the title compound, C14H12F8N2, contains one tetra­fluoro­pyrrolidine system and one half-mol­ecule of benzene; the latter, together with a second heterocyclic unit, are completed by symmetry, with a twofold crystallographic axis crossing through both the middle of the bond between the C atoms bearing the heterocyclic rings and the opposite C—C bonds of the whole benzene mol­ecule. The pyrrolidine ring shows an envelope conformation with the apex at the N atom. The dihedral angle between the least-squares plane of this ring and the benzene ring is 36.9 (5)°. There are intra­molecular C—H⋯N inter­actions generating S(6) ring motifs. In the crystal structure, the mol­ecules are linked by C—H⋯F inter­actions, forming chains parallel to [010]

Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 degrees C) and two diurnally fluctuating treatments (28-31 and 30-33 degrees C with daily means of 29 and 31 degrees C, respectively) simulating the 3 degrees C diel oscillations at 3m depth on the Luhuitou fringing reef (Sanya, China). Results showed that the thermal stress on settlement at 31 degrees C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII) was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 degrees C, oscillations of 3 degrees C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 degrees C in fluctuating 31 degrees C elicited a notable reduction in calcification compared to constant 31 degrees C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth

Fat fraction quantification of lumbar spine: comparison of T1-weighted two-point Dixon and single-voxel magnetic resonance spectroscopy in diagnosis of multiple myeloma

PURPOSEWe aimed to investigate the value of T1-weighted two-point Dixon technique and single-voxel magnetic resonance spectroscopy (MRS) in diagnosis of multiple myeloma (MM) through quantifying fat content of vertebral marrow.METHODSA total of 30 MM patients and 30 healthy volunteers underwent T1-weighted two-point Dixon and single-voxel MRS imaging. The fat fraction map (FFM) was reconstructed from the Dixon images using the equation FFM = Lip/In, where Lip represents fat maps and In represents in-phase images. The fat fraction (FF) of MRS was calculated by using the integral area of Lip peak divided by the sum of integral area of Lip peak and water peak.RESULTSFF values measured by the Dixon technique and MRS were significantly decreased in MM patients (45.99%±3.39% and 47.63%±4.38%) compared with healthy controls (64.43%±0.96% and 76.22%±1.91%) (P < 0.001 with both methods). FF values measured by Dixon technique were significantly positively correlated to those measured by MRS in MM (r = 0.837, P < 0.001) and healthy control group (r = 0.735, P < 0.001), respectively. There was no significant difference between area under the curve (AUC) obtained by the Dixon technique (0.878±0.047; range, 0.785 to 0.971; optimal cutoff, 56.35 for healthy controls vs. MM) and MRS (0.883±0.047; range, 0.791 to 0.974; optimal cutoff, 61.00 for healthy controls vs. MM). The ability of Dixon technique to differentiate MM group from healthy controls was equivalent to single-voxel MRS.CONCLUSIONRegarding detection of fat contents in vertebral bone, T1-weighted two-point Dixon technique exhibited equivalent performance to single-voxel MRS in the diagnosis of multiple myeloma. Moreover, two-point Dixon is a more convenient and stable technique for assessing bone marrow changes in MM patients than single-voxel MRS