Cimaterol and clenbuterol residue analysis by HPLC-HPTLC in liver.

A method has been developed for the analysis of cimaterol and clenbuterol residues in liver, with detection limits of 0.25 micrograms/kg and 0.5 micrograms/kg, respectively. The recovery varied from 55% to 60%. After extraction, a clean-up procedure with Baker-spe C-18 columns was performed. The two chemical compounds of interest were eluted with methanol. Cimaterol and clenbuterol were quantitatively determined by high-performance liquid chromatography (HPLC) using an RP-Select B (5 microns) column and a post-column reaction procedure. The positive results were confirmed by high-performance thin-layer chromatography (HPTLC) as this technique reaches the same level of sensitivity as the HPLC method.     

Magnetic resonance findings in skeletal muscle tears

Magnetic resonance (MR) images of skeletal muscle tears can clearly delineate the severity of muscle injury. Although MR imaging is seldom necessary in patients with acute muscle trauma, it can be helpful in deciding on clinical management. The two major MR findings in acute muscle tears are deformity of the muscle and the presence of abnormal signal reflecting hemorrhage and edema. In acute tears, methemoglobin within the extravascular blood causes high-signal areas on both T1- and T2-weighted images. With partial tears, the blood may dissect in a distinctive linear pattern along the muscle bundles and fibers. As healing begins, the muscle signal diminishes, first on the T1-weighted images and then on the T2-weighted images. When there is residual abnormal signal on images obtained more than several months after the injury, it is presumed to represent hemorrhage from recurrent tears. In patients with a questionable history of a remote injury, the clinical presentation may be that of persistent pain or a soft tissue mass. In these cases MR imaging may identify the cause of the pain and can exclude a neoplasm by proving that the mass is a hypertrophied or retracted muscle. Thus, MR imaging has a limited, but occasionally important role in selected patients with skeletal muscle tears.     

Hybrid finite-element method for discretising cylindrically symmetric parts in electrotechnical models

In many technical devices such as transformers and electrical machines, large differences in geometric dimensions are observed. As a consequence, the generation of a 3D computational grid for the whole device leads to unacceptably large numbers of elements or can even fail. In addition to the commonly applied cartesian or cylindrical symmetries of the overall geometry, the model can be subdivided into parts featuring translational or cylindrical symmetries. Such parts are discretised separately, accounting for the local symmetry, and are then combined with the surrounding 3D model. Excitations and boundary conditions of the submodels are not necessarily symmetric but are expected to be smooth in the direction of the symmetry. Then, the field distribution at the interface is well approximated by a set of spectral elements along the dimension of symmetry. Coupling between the model parts is carried out by means of Lagrange multipliers. A single-phase transformer with thin insulation sheets is taken as an example to illustrate the proposed hybrid discretisation. The cross-section of the cylindrically symmetric part containing thin sheets, is represented by a fine 2D finite-element mesh so that all the geometrical details can be resolved, and the rest of the structure is discretised by a 3D mesh. Nevertheless, a fully 3D field distribution is calculated in all model parts. Only a small number of harmonic functions is needed to account for the azimuthal field variation at the cylindrical interface. Hence, the number of unknowns in the numerical model is reduced significantly, while a high level of accuracy is maintained