[Hollow fiber liquid phase microextraction of tramadol from water and biological samples].

A novel technique of liquid phase microextraction supported by hollow fiber membrane (LPME-HFM) was applied to extract tramadol in tap water, urine and human plasma. At room temperature (20 degrees C), polyvinylidene fluoride hollow fiber membrane (PVDF-HFM) was employed. In the procedure of extraction, 4 microL of organic solvent (toluene) was used in individual extraction.

Atmospheric PCDD/F and PCB levels implicated by pine (Cedrus deodara) needles at Dalian, China.

Dalian is a seaside city situated in the northeastern monsoon area of China. For the first time, levels of PCDD/F and PCB congeners in pine (Cedrus deodara) needles of Dalian urban areas were investigated. Two sampling campaigns with 17 sampling points were performed in 2002.

Mechanisms of polarized growth and organelle segregation in yeast.

Cell polarity, as reflected by polarized growth and organelle segregation during cell division in yeast, appears to follow a simple hierarchy. On the basis of physical cues from previous cell cycles or stochastic processes, yeast cells select a site for bud emergence that also defines the axis of cell division. Once polarity is established, rho protein-based signal pathways set up a polarized cytoskeleton by activating localized formins to nucleate and assemble polarized actin cables.

Stable and dynamic axes of polarity use distinct formin isoforms in budding yeast.

Bud growth in yeast is guided by myosin-driven delivery of secretory vesicles from the mother cell to the bud. We find transport occurs along two sets of actin cables assembled by two formin isoforms. The Bnr1p formin assembles cables that radiate from the bud neck into the mother, providing a stable mother-bud axis.

Linear free energy relationships for dechlorination of aromatic chlorides by Pd/Fe.

Reductive dechlorination rate constants for five chlorobenzenes in the presence of Pd/Fe as catalyst were determined experimentally. Linear free energy relationships (LFER) for the dechlorination rate constants of five chlorobenzenes and three chlorophenols were developed by partial least squares (PLS) regression based on quantum chemical parameters computed by PM3 Hamiltonian. The optimal LFER model obtained is logk=-1.

Biomechanical principle of arcus plantaris and its clinical application.

OBJECTIVE: To analyze the principle mechanism of the arcus plantaris and its clinical application. METHODS: The states of forces sustained by the arcus plantaris were analyzed and calculated according to the mechanism of the quadratic parabolic arch. RESULTS: The aponeurosis plantaris corresponded to the pull rod of the arcus plantaris.