The title structure, [Rh₂(C₁₁H₁₄NO)₄(C₇H₅N)₂], contains a dinuclear Rh complex of point symmetry -4 with an Rh-Rh unit and two benzonitrile ligands located in special positions along the twofold axis passing through -4. Four symmetry-equivalent mesitylacetamidate ligands bridge the Rh-Rh unit. Thus, each Rh(II) atom has an approximately octa-hedral coordination by one Rh [Rh-Rh = 2.4290 (6) Å], two acetamidate O atoms trans to each other [Rh-O = 2.044 (3) Å], two acetamidate N atoms trans to each other [Rh-N = 2.091 (4) Å], and a benzonitrile N atom trans to Rh [Rh-N = 2.222 (3) Å]. The structure is held together by weak van der Waals forces.

The title structure, [Rh-2(C11H14NO)(4)(C7H5N)(2)], contains a dinuclear Rh complex of point symmetry 4 with an Rh-Rh unit and two benzonitrile ligands located in special positions along the twofold axis passing through 4. Four symmetryequivalent mesitylacetamidate ligands bridge the Rh-Rh unit. Thus, each Rh II atom has an approximately octahedral coordination by one Rh [Rh- Rh = 2.4290 (6)angstrom], two acetamidate O atoms trans to each other [Rh-O = 2.044 (3) angstrom], two acetamidate N atoms trans to each other [Rh-N = 2.091 (4) angstrom], and a benzonitrile N atom trans to Rh [Rh-N = 2.222 (3) angstrom]. The structure is held together by weak van der Waals forces.

The title structure, [Rh2(C11H14NO)4(C7H5N)2], contains a dinuclear Rh complex of point symmetry -4 with an Rh—Rh unit and two benzonitrile ligands located in special positions along the twofold axis passing through -4. Four symmetry-equivalent mesitylacetamidate ligands bridge the Rh—Rh unit. Thus, each RhII atom has an approximately octahedral coordination by one Rh [Rh—Rh = 2.4290 (6) Å], two acetamidate O atoms trans to each other [Rh—O = 2.044 (3) Å], two acetamidate N atoms trans to each other [Rh—N = 2.091 (4) Å], and a benzonitrile N atom trans to Rh [Rh—N = 2.222 (3) Å]. The structure is held together by weak van der Waals forces.

The title structure, [Rh2(C11H14NO)4(C7H5N)2], contains a dinuclear Rh complex of point symmetry -4 with an Rh—Rh unit and two benzonitrile ligands located in special positions along the twofold axis passing through -4. Four symmetry-equivalent mesitylacetamidate ligands bridge the Rh—Rh unit. Thus, each RhII atom has an approximately octahedral coordination by one Rh [Rh—Rh = 2.4290 (6) Å], two acetamidate O atoms trans to each other [Rh—O = 2.044 (3) Å], two acetamidate N atoms trans to each other [Rh—N = 2.091 (4) Å], and a benzonitrile N atom trans to Rh [Rh—N = 2.222 (3) Å]. The structure is held together by weak van der Waals forces.

Rotational plots at the Agriculture Canada Experimental Farm at Indian Head, Saskatchewan, have been receiving annual applications of amine and ester formulations of 2,4-D since 1947, and MCPA amine since 1953. These research plots are unique world-wide for the length of time of application of these herbicides. Wheat yield data from 1973 to 1989 indicate that the continuous use of the herbicides significantly increased yields compared to untreated control plots. In both 2,4-D and MCPA treatments, susceptible weeds were greatly reduced, but not eliminated. No new major weed species became established. After 35 yr of 2,4-D application there were no ecologically significant effects on selected soil biochemical processes, nor had the herbicides interfered with the normal cycling of carbon, nitrogen, or phosphorus. Following 33 yr of MCPA treatments there were, except for yeasts, no significant changes in microbial biomass or microbial populations. After 40 successive treatments of 2,4-D amine and ester, and 35 annual applications of MCPA, herbicide residues in the 0- to 15-cm and 15- to 30-cm soil depths were less than detectable limits of < 0.03 kg acid ha-1. Under laboratory conditions, the breakdown of added 2,4-D and MCPA was faster in soils receiving continuous herbicide applications than in soil from untreated control plots, suggesting that some soil microbiological adaptation had occurred. It can be concluded that there have been no adverse effects on crop productivity of the soil from the long-term use of 2,4-D and MCPA.

Abstract Previously we reported that in sheep dippers exposed to organophosphates the frequency of paraoxonase (PON1) polymorphisms differed between those with or without self-reported ill health. We have now examined whether polymorphisms in other genes involved in xenobiotic metabolism alter disease risk in this population. There were elevated but non-significant risks associated with the CYP2D6 WT genotype (odds ratio (OR) 1.47, 95% CI 0.83–2.60), or a GSTP1*B or *C allele (OR 1.37, 95% CI 0.88–2.01) or being GSTM1*2/GSTT1*2 homozygous (OR 1.61, 95% CI 0.74–3.48). Similar results were generally obtained after the exclusion of subjects to obtain a more homogenous case-referent population: for double null GSTM1 and GSTT1 homozygotes the OR was 2.06 (95% CI 0.85–2.04). In those also likely to have been exposed to diazinon, risks associated with a GSTP1*B or *C allele (OR 1.82, 95% CI 0.92–3.63) or a GSTM1*2/GSTT1*2 homozygous (OR 2.60, 95% CI 0.72–10.42) were elevated but not to a significant extent. Risk associated with PON1 genotype and phenotype varied with CYP2D6 and GSTP1 genotype but not consistently with a priori hypotheses. Further work is necessary to delineate more clearly pathways of organophosphate activation and non-PON1 pathways of detoxification and to confirm whether CYP and GST polymorphisms alter disease risk in populations exposed to organophosphates.

The preferred in-plane orientation of the magnetization in Co thin films can be switched to out-of-plane either by decreasing the thickness of the Co layer at fixed temperature, or the thickness of the Au cap layer, or by decreasing the temperature at fixed layer thickness.Recently, we have characterized the Co/Au system grown in-situ on a W(110) single crystal and found a novel behaviour, where a SRT can be observed over a wider range of Co thicknesses, depending on temperature and cap-thickness.Furthermore, we found a competing situation where the system was possible to stabilize both with an in-plane and an out-of-plane remanent magnetization for very thin Co layers.Our recent in-situ XMCD work indicates (a) for thick Co films the magnetization remained fully in-plane upon capping with Au, for all Au cap thicknesses.In the thin limit of Co thickness (case b) immediately after capping with Au the magnetization turned fully out-of-plane, and the overall magnetization increased upon further adding of Au.XMCD results will be discussed regarding the magnitude of magnetic moments, and especially on how the orbital moment varies in all cases which we studied.In short our results indicate that in the case (a) no variation of the orbital moment took place upon reorientation, in contrast to case (b).These observations reveal a more subtle dependence of the magnetic energies on the real space structure and add novel possibilities in order to create novel canted magnetic phases not observed earlier by tuning the growth parameters of this system, beyond what is reported in the literature.

BACKGROUND Serum paraoxonase (PON1) provides protection against organophosphate induced toxicity. Recently we reported that the frequency of paraoxonase polymorphisms in sheep dippers with self-reported chronic ill-health differed from that in dippers with a similar dipping history but no ill-health. As these analyses may have included subjects with conditions unrelated to organophosphate exposure, the aim of this study was to examine whether the risk associated with PON1 polymorphisms varied using a more homogenous case and referent population. METHODS Each subject completed a detailed symptom questionnaire and their general practitioner was asked whether there was any history of neurological disease that could be confused with the effects of organophosphate poisoning. Subjects were then excluded both on clinical grounds and where identified as atypical on discriminant analysis. RESULTS Risk associated with the PON1 192 and 55 genotypes altered little with these changes in the population. CONCLUSIONS These findings are consistent with the hypothesis that organophosphates contribute to the self-reported ill-health of sheep dippers.

Pulmonary interstitial emphysema (PIE) is a well-described complication of positive-pressure mechanical ventilation and respiratory distress syndrome (RDS) in the newborn.' Although PIE is a common diagnosis in the neonatal intensive care unit (NICU), we are not aware of any reports documenting its presentation in an outpatient setting.2 We present a case of PIE in a former premature infant that occurred 1 month after extubation and 1 week after discharge with no subsequent evidence of respiratory distress until presentation. This patient suggests that PIE can have an insidious onset and that a delayed presentation of PIE should be included in the differential for respiratory distress in a former preterm infant recovering from severe RDS even after hospital discharge.

Frequent pesticide applications to gulf courses causes concern that surface water may become contaminated, We hypothesized that runoff potential of these pesticides could be predicted by the recently developed Opus model. We conducted a 3-yr field study measuring surface runoff of water and dimethylamine salts of 2,4-D [(2,4-dichlorophenoxy) acetic acid], dicamba (3,6-dichloro-2-methylphenoxy-benzoic acid), and mecoprop [(+/-)-2-(4-chloro-2-methylphenoxy)-propanoic acid]. Twelve 7.4 m by 3.7 m plots of 'Tifway 419' bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt Davy) were managed as a golf course fairway. Simulated rainfall was applied at an average intensity of 29 mm h(-1) 1 d before and 1, 2, 4, and 8 d after pesticide application for 0.92, 1.75, 1.75, 0.92, and 0.92 h, respectively. Average annual runoff loss was 9.13, 15.41, and 10.82% of applied 2,4-D, dicamba, and mecoprop, respectively. Both mass and concentration of pesticide runoff decreased rapidly, with the first posttreatment event runoff averaging 74.5, 71.7, and 73.0% of the total runoff of 2,4-D, dicamba, and mecoprop, respectively. The Opus model adequately simulated runoff [R(2) = 0.897 and normalized root mean square error (NRMSE) = 24.6%], The 2,4-D in runoff was better simulated by complete-kinetic sorption (R(2) = 0.876, NRMSE = 60.2%) than by equilibrium sorption (R(2) = 0.848, NRMSE = 68.2%). Opus did not accurately simulate 2,4-D over all runoff events, but simulated 2,4-D in the first posttreatment runoff within a factor of 2 of those measured.

Surface runoff or irrigation water contaminated with herbicides may cause crop damage and result in inadvertent residues in the crop. Rotational crops may also be damaged due to the persistence of leached herbicides within the root zone. An 11-yr field experiment was carried out to address these issues through repeated flood-irrigations of alfalfa (Medicago sativa L. 'Roamer') with water containing various concentrations (0, 10, 100 and 1000 µg L −1 ) of monuron or simazine. The experimental site, on an alluvial clay soil, was flood-irrigated for 8 yr with a total of 32 irrigations, then oat (Avena sativa L. 'Harmon') was grown for 3 yr under dryland conditions as a sensitive bioassay crop. Based on alfalfa forage yield, repeated applications of water containing up to 100 µg L −1 of either monuron or simazine did not show any harmful effects on the crop. However, the 1000 µg L −1 treatments caused cumulative yield reductions with greatest deleterious effect being caused by simazine (up to 55% yield reduction). After 7 yr of irrigation, inadvertent residues of both herbicides were consistently detected in the crop, but only for the 1000 µg L −1 treatments. Average concentrations of monuron in the alfalfa foliage were 0.94 and 1.76 mg kg −1 for the first and second cuts, respectively, whereas corresponding values for simazine were 0.31 and 0.64 mg kg −1 . Approximately 4 and 12% of the total amounts applied remained in the soil profile for monuron and simazine, respectively. Herbicide residues to 1.5 m soil depth decreased with increasing depth with half of the total being present in the top 0.15 m, and they were detectable only for the 100 and 1000 µg L −1 treatments. Only soil residues of simazine from the 1000 µg L −1 rate of application reduced oat yields extensively. These yield reductions occurred only during the first 2 yr under dryland production. Key words: Herbicide-contaminated irrigation water, crop damage, herbicide residues, alfalfa, simazine, monuron

Research was conducted to evaluate the potential movement of dithiopyr [S,S-dimethyl2-(difluoromethyl)-4-(2-methylpropyl)-6- (trifluoromethyl)-3,5-pyridinedicarbothioate] from golf courses. Dithiopyr was applied as granule and emulsifiable concentrate (EC) formulations to 'Penncross' creeping bentgrass (Agrostis stolonifera L.) and 'Tifdwarf' hybrid bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] in simulated greens. Less than 0.6% of the dithiopyr was transported through the rooting media (a mixture containing at least 97% coarse sand by weight with sphagnum neat moss). Dithiopyr concentrations in the leachate, transported through the greens, did not exceed 3 mu g L(-1). Most of the dithiopyr (11-31%) was detected in the top 0 to 12.5 cm of rooting media at the end of the greenhouse experiments and as much as 20% of the applied dithiopyr was removed with the leaf clippings over the duration of the greenhouse experiments. The highest concentration of dithiopyr transported in the runoff water from simulated golf course fairways did not exceed 40 mu g L(-1). Generally, the concentration of dithiopyr in the runoff water was higher when applied as an EC formulation compared with the granule formulation at 1 d after treatment (DAT). The dithiopyr concentration, in the runoff water, had decreased to near 9 mu g L(-1) at the 8 DAT sampling period and less than 2.0% of the applied dithiopyr was transported from the simulated fairways.

Research was conducted in central Georgia to determine the influence of norflurazon on bermudagrass stand and production when applied to newly sprigged bermudagrass and in the spring to dormant bermudagrass. Norflurazon at rates up to 1.12 kg ai/ha on newly sprigged bermudagrass caused moderate chlorosis to the emerging leaves but did not adversely influence stand density or ground cover at 60 and 90 days after treatment (DAT). Norflurazon applied to dormant bermudagrass the spring of 1993 resulted in greater than 50% foliage chlorosis at rates ≥ 1.68 kg/ha. Foliage chlorosis was 94% on bermudagrass treated with 3.36 kg/ha 30 DAT and at spring growth initiation. However, chlorosis level was reduced when bermudagrass began rapid growth. Forage production was not influenced by the early season chlorosis when compared to nontreated areas or areas treated with diuron at 1.12 kg/ha and the weed free check.

Corpus luteum growth and function were monitored daily for a complete estrous cycle by ultrasonography and peripheral serum progesterone in lactating, cyclic Holstein cows during spring (n = 8) and summer (n = 8). For spring and summer, respectively, daily ambient temperatures (mean +/- SEM) were 21.2 +/- .9 and 31.1 +/- .3 degrees C. In summer compared with spring, early morning rectal temperatures were higher on d 1, 2, and 3, when the corpus luteum was forming, and on d 15 and 19. The length of the luteal phase and the corpus luteum cross-sectional area were similar for the two seasonal groups. Central luteal cavities were observed during spring and summer. Serum progesterone secreted between d 6 and 18 was lower during summer. In addition, progesterone concentrations during the entire luteal phase and the peak magnitude of progesterone tended to be lower during summer. Suppressed luteal function may contribute to low fertility when cows are inseminated during summer.

Aqueous extracts of tissue from the test species (giant foxtail, green foxtail, yellow foxtail, bahiagrass, barnyardgrass, Johnsongrass and large crabgrass) harvested at the vegetative and mature stages were tested for allelopathy on seed germination and seedling growth of the bioassay species (alfalfa and Italian ryegrass). Tissues harvested from large crabgrass and barnyardgrass were found not to be allelopathic; only tissue harvested from the five other test species during the mature stage of plant growth exhibited allelopathic characteristics. Extracts of stem material reduced seed germination and seedling growth for both bioassay species. It was estimated that 0.30/0.33, 0.23/0.18, 0.20/0.21, 0.31/0.32 and 0.38/0.19% aqueous extracts of mature Johnsongrass, bahiagrass, giant foxtail, green foxtail and yellow foxtail stem tissue resulted in a 50% reduction in seed germination/seedling growth of Italian ryegrass, respectively. Concentrations in a similar range resulted in 50% reduction in seed germination and seedling growth in the alfalfa bioassay. The potential concentration for foliage tissue in soil solution of the pasture ecosystem for Johnsongrass, bahiagrass, giant foxtail, green foxtail, and yellow foxtail foliage tissue would be 3.2, 1.0, 2.0, 1.4 and 1.4%, respectively. The allelopathic characteristics of these species could therefore be of economic importance in the pasture ecosystem when overseeding the pasture with grass and legume species.

Dissipation of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), applied as a 1:1 mixture of the n-butyrate and iso-octanoate esters, in the air, crop, and soil components was measured in a spring wheat (Triticum aestivum L.) field, both during and following its application. Drift losses during spraying were < 1% of the amount applied, with no phenol derivative being detected in air samples collected during application. Following application, cumulative vapor loss for the n-butyrate and iso-octanoate esters (phenol equivalent, p.e.) over the 5-d postapplication period were estimated to be 16 and 7%, respectively. Little or no free phenol residues were detected in the air above the treated field. The crop canopy intercepted approximately 20% of the application. Ester deposits on plant surfaces were rapidly dissipated with > 75% of the total ester residues on the crop being lost or hydrolyzed 24 h after treatment. There were no detectable residues in the seed or straw at harvest. In the soil, the half-lives of n-butyrate and iso-octanoate were < 1 and similar to 4 d, respectively. Hydrolysis was, however, more rapid under moist soil conditions, with the n-butyrate being converted more rapidly to phenol than the iso-octanoate. Phenol breakdown was also moisture dependent but much slower, with > 95% dissipation occurring only after 8 wk.

Fourteen lactating and cycling Holsteins in each of two summers were assigned randomly to pens in a free-stall barn either with or without overhead fans to study the effect of fan cooling on certain endocrine and behavioral responses during the estrous cycle. After an adjustment period of 8 d in the first summer and 21 d in the second summer, jugular cannulas were inserted, and 25 mg of PGF2alpha were injected. After injection, blood samples were collected frequently for 84 h in the first summer and 88 h in the second summer, followed by collection three times weekly for 3 wk thereafter each summer. Rectal temperatures were lower in the group cooled by fans than in the control group each summer. Luteal progesterone secretion tended to be greater in the fan group each summer; area under the luteal phase curve was significantly higher than for controls during the second summer. There was tendency for more preovulatory surges of LH and higher estrous response rates in the fan group during the second summer. Thus, fan cooling of lactating dairy cows for several weeks before anticipated breeding provides potential for more efficient reproductive performance during the summer.