Comparison of the persistence of atrazine and metolachlor under field and laboratory conditions.

A study was carried out in a loamy soil to evaluate the degradation of atrazine and metolachlor under laboratory-controlled and field-variable conditions as a function of temperature and soil moisture content. In laboratory trials, metolachlor showed fast degradation, with half-lives from 100 to 5.7 days in a temperature range from 5 to 35 degrees C at 100% of field capacity, whereas in the same conditions the degradation rate of atrazine was relatively slow, with half-lives from 407 to 23 days. Modeling of laboratory degradation data to predict field persistence was carried out. Field persistence of atrazine and metolachlor was measured in the same soil during the corn growing seasons in 1993, 1994, and 1996. In the three years the mean half-dissipation times for atrazine and metolachlor were 36 and 21 days, respectively. Calculations from model equations gave acceptable prediction of field dissipation of both herbicides. Limitations and perspectives of employed modelization procedure are discussed.

Effect of closed chain exercise on quadriceps femoris peak torque and functional performance.

OBJECTIVE: To determine the effect of a 6-week leg press training program on quadriceps femoris peak torque and lower extremity functional performance. DESIGN AND SETTING: A 2 x 3 factorial design. A private university-based outpatient physical therapy clinic was used for testing. The university strength and conditioning center was used for training sessions. SUBJECTS: A volunteer sample of thirty nonathletic, collegeage females participated. All thirty subjects completed the study. MEASUREMENTS: Subjects were randomly assigned to either a control group (G(con)) or an exercise group that performed isotonic unilateral leg presses through either 0 to 60 degrees (G(60)) or 0 to 90 degrees (G(90)) of knee flexion. Subjects trained 3 days/wk for 6 weeks using the DAPRE technique. Pre and post isokinetic testing of the quadriceps femoris at 60 degrees /sec and hop tests for distance and time were measured. RESULTS: Both training groups showed significant pre-post increases (p < .05) for: concentric peak torque, eccentric peak torque, and hop test for distance. G\(60) showed a significant decrease in hop test for time values. Significant increases (p < .05) in eccentric peak torque was seen between training groups and the control group, concentric peak torque was significantly greater only in G(90) as compared to G(con), on. No significant differences were observed between G(60) and G(90) for any of the measured variables. There were no differences between the three groups for any of the functional hop test measurements. CONCLUSIONS: Unilateral leg press exercise performed through 0 to 90 degrees of knee flexion increases concentric and eccentric peak torque while training from 0 to 60 degrees improves eccentric torque. No changes in functional performance as measured by hop tests were seen in any groups. Transference between closed kinetic chain (CKC) exercise and open kinetic chain testing was supported, but not between CKC and functional performance testing.

Monitoring of herbicide pollution in water by capillary electrophoresis.

In recent years, capillary electrophoresis (CE) has demonstrated itself to be an extremely powerful analytical technique. However, CE has not yet been fully evaluated for the environmental analysis of herbicides. In this paper, the potential and drawbacks of CE for the separation and detection of herbicides in water sources are outlined. Details are given both on the applicability of CE to trace level monitoring of herbicides in water sources and on its usefulness in studies regarding the environmental behaviour of herbicides in water systems.

Separation and detection of herbicides in water by micellar electrokinetic capillary chromatography.

The herbicides linuron, metolachlor, atrazine and metsulfuron were analysed using micellar electrokinetic capillary chromatography (MECC) after a 1000-fold concentration step by solid-phase extraction (SPE). Recoveries ranged from 80 to 92%, depending on the concentration and the number of active substances in the sample. Furthermore, the hydrolysis products of metsulfuron were analysed by MECC and by gas chromatography-mass spectrometry (GC-MS). Representative MECC and GC-MS profiles are shown and the structures of the hydrolysis products are proposed on the basis of their chromatographic and mass spectra features. A tentative pathway for the degradation of metsulfuron is proposed.