Notatki o faunie skąposzczetów (Oligochaeta) Polski, 2.

Poly[tetra­aqua­bis­(μ3-oxalato-κ5 O 1,O 2:O 1′:O 1′,O 2′)(μ2-oxalato-κ4 O 1,O 2:O 1′,O 2′)dipraseodymium(III)]

In the title complex, [Pr(2)(C(2)O(4))(3)(H(2)O)(4)](n), the two independent Pr(III) ions are both nine-coordinated in a distorted monocapped square-anti-prismatic geometry by seven O atoms from four oxalate ligands and two water mol-ecules. The Pr(III) ions are bridged by the oxalate ligands, forming a layer parallel to (001). O-H⋯O hydrogen bonds connect the layers.

Poly[di-μ-aqua-di­aqua­bis­(μ7-oxalato-κ9 O 1:O 1:O 1,O 2:O 2:O 2′:O 2′,O 1′:O 1′)calciumdicaesium]

In the title compound, [CaCs2(C2O4)2(H2O)4] n , the Ca(2+) ion, lying on a twofold rotation axis, is coordinated by four O atoms from two oxalate ligands and two bridging water mol-ecules in an octa-hedral geometry. The Cs(+) ion is coordinated by seven O atoms from six oxalate ligands, one bridging water and one terminal water mol-ecule. The oxalate ligand displays a scarce high denticity. The...

O + + H 2 O „ + M ... \ H 5 O 2 + „ + M ...

Biomechanical analysis of Oligochaeta crawling.

Hydrostatic skeletons, such as that of Oligochaeta and Hirudinea, allow the locomotion of animals with soft segmented bodies. In this paper crawling of Oligochaeta, and in particular that of earthworm (Lumbricus terrestris), is analyzed from a biomechanical point of view, starting from the experimental kinematic description of deformations coupled with a simple friction model. The analysis is a...

Bis(μ-pyridine-2,4-dicarboxyl­ato)-κ3 N,O 2:O 2;κ3 O 2:N,O 2-bis­[triaqua­magnesium(II)]

In the title centrosymmetric Mg(II) complex, [Mg(2)(C(7)H(3)NO(4))(2)(H(2)O)(6)], each Mg cation is N,O-chelated by a pyridine-2,4-dicarboxyl-ate dianion and is coordinated by three water mol-ecules. A carboxyl-ate O atom from the neighboring pyridine-2,4-dicarboxyl-ate dianion bridges the Mg cation to complete the MgNO(5) distorted octa-hedral coordination geometry. The dinuclear complex mol-e...