Magnetic field inhomogeneities due to CO 2 incubator shelves: a source of experimental confounding and variability?

A thorough assessment of the static magnetic field (SMF) inside a CO 2 incubator allowed us to identify non-negligible inhomogeneities close to the floor, ceiling, walls and the door. Given that incubator's shelves are made of a non-magnetic stainless steel alloy, we did not expect any important effect of them on the SMF. Surprisingly, we did find relatively strong distortion of the SMF due to shelves. Indeed, our high-resolution maps of the SMF revealed that distortion is such that field intensities differing by a factor of up to 36 were measured on the surface of the shelf at locations only few millimetres apart from each other. Furthermore, the most intense of these fields was around five times greater than the ones found inside the incubator (without the metallic shelves in), while the lowest one was around 10 times lower, reaching the so-called hypomagnetic field range. Our findings, together with a survey of the literature on biological effects of hypomagnetic fields, soundly support the idea that SMF inhomogeneities inside incubators, especially due to shelves' holes, are a potential source of confounding and variability in experiments with cell cultures kept in an incubator.

Crystal structures of three mercury(II) complexes [HgCl2L] whereLis a bidentate chiral imine ligand

The crystal structures of three complexes [HgCl2L] were determined, namely, (S)-(+)-dichlorido[1-phenyl-N-(pyridin-2-ylmethylidene)ethylamine-κ2N,N′]mercury(II), [HgCl2(C14H14N2)], (S)-(+)-dichlorido[1-(4-methylphenyl)-N-(pyridin-2-ylmethylidene)ethylamine-κ2N,N′]mercury(II), [HgCl2(C15H16N2)], and (1S,2S,3S,5R)-(+)-dichlorido[N-(pyridin-2-ylmethylidene)isopinocampheylamine-κ2N,N′]mercury(II), [HgCl2(C16H22N2)]. The complexes consist of a bidentate chiral imine ligand coordinating to HgCl2and crystallize with four independent molecules in the first complex and two independent molecules in the other two. The coordination geometry of mercury is tetrahedral, with strong distortion towards a disphenoidal geometry, as a consequence of the imine bite angle being close to 70°. The Cl—Hg—Cl angles span a large range, 116.0 (2)–138.3 (3)°, which is related to the aggregation state in the crystals. For small Cl—Hg—Cl angles, complexes have a tendency to form dimers,viaintermolecular Hg...Cl contacts. These contacts become less significant in the third complex, which features the largest intramolecular Cl—Hg—Cl angles.

Propagation of Different Types of Inflow Distortions through a Contra Rotating Fan Stage

This paper aims to explain the propagation of different types of inflow distortions through a contra rotating fan stage. Inflow distortions like circumferential, radial and complex distortions were artificially generated using meshes of different porosities. The overall effects of these distortions are determined in the terms of the fan performance map. It is attempted to explain the propagation of inflow distortion using distortion descriptors like circumferential intensity, circumferential extent and radial intensity at the design mass flow rate. These are described for different speed combinations of both the rotors at the inlet, the exit of rotor-1 and at the exit of rotor-2. It is important to observe here that even for purely circumferential inflow distortion, the distortion does not remain purely circumferential, rather it propagates both circumferentially and radially along the stage. For the hub-strong complex inflow distortion, the higher magnitude of circumferential intensity and circumferential extent at the exit of rotor-1 clearly indicates the strong distortion effect that leads to poor performance of the stage amongst all distortion configurations studied. With radial inflow distortion, the radial redistribution of the flow at the exit of rotor-1 plays an important role in the performance of the rotor-2 and thereby for the stage.

Study on Extraordinary Transport Behaviors of Polycrystalline La-Sb-Mn-O Ceramic

The transport properties of polycrystalline La0.9Sb0.1MnO3(LSMO) bulk prepared by the solid-state reaction were investigated. We find that transport behaviors heavily depend on the synthesis process. The resistivity of LSMO1 for less rubbing time shows one metal-insulator transition (MIT) peak at temperature of 201 K, while the resistivity of LSMO2 for more rubbing time shows a MIT and a shoulder at about 240 and 140 K, respectively. The magnetoresistance (MR) ratio of LSMO2 reaches 41% under magnetic field of 2 T. Moreover, the MR ratio keeps significant value within broad temperature range. The infrared (IR) absorption spectra of LSMO2 show that the stretch-mode peak split into two Gaussian peaks with the gap about 70 cm-1. This large splitting indicates there are strong distortion and disorder in LSMO2 sample. The results are interpreted in terms of the disorder system and phase separation in perovskite manganites.

Chloroxiphite Pb3CuO2(OH)2Cl2: structure refinement and description in terms of oxocentred OPb4 tetrahedra

The crystal structure of chloroxiphite, Pb3CuO2(OH)2Cl2, from Merehead Quarry (monoclinic, P21/m, a = 6.6972(8), b = 5.7538(5), c = 10.4686(14) Å,β = 97.747(10)°, V = 399.72(8) Å3) has been refined to R1 = 0.041. The structure contains three symmetrically unique Pb sites and one Cu site. The strong distortion of the Pb2+ coordination polyhedra is due to the stereoactivity of the s2 lone electron pairs on the Pb2+ cations. The Cu-site is coordinated by four OH- groups to form an almost planar Cu(OH)4 square that is complemented by two apical Cl– anions, forming an elongated [Cu(OH)4Cl2] octahedron. Because of the large size and variability of coordination polyhedra around Pb2+ cations and the strength of the Me–O bonds in comparison to the Me–Cl bonds (Me = metal), it is convenient to describe the structure of chloroxiphite in terms of oxocentred OPb4 tetrahedra. The O1 atom is tetrahedrally coordinated by four Pb2+ cations forming relatively short and strong O–Pb bonds. The OPb4 tetrahedra link together via common edges to form [O2Pb3]2+ double chains. The difference between chloroxiphite and other natural oxyhalides is the presence of Cu2+ cations which form an independent structural unit that links to units formed by OPb4 tetrahedra. In this sense, chloroxiphite can be considered as a modular structure consisting of both strong cation- and anion-centred units.