The effects of pesticide mixtures on degradation of pendimethalin in soils

Most agronomic situations involve a sequence of herbicide, fungicide, and insecticide application. On the other hand, use of pesticidal combinations has become a standard practice in the production of many agricultural crops. One of the most important processes influencing the behavior of a pesticide in the environment is its degradation in soil. It is known that due to several pesticide applications in one vegetation season, the pesticide may be present in mixtures with other pesticides or xenobiotics in soil. This study examines the role which a mixture of chemicals plays in pesticide degradation. The influence of other pesticides on the rate of pendimethalin (PDM) degradation in soil was measured in controlled conditions. Mixtures of PDM with mancozeb or mancozeb and thiamethoxam significantly influenced the degradation of pendimethalin under controlled conditions. The second type of mixtures, with metribuzin or thiamethoxam, did not affect the behavior of pendimethalin in soil. Also, we determined the influence of water content on the rate of pendimethalin degradation alone in two soils and compared it to the rate in three pesticide mixtures. We compared two equations to evaluate the predictors of the rate of herbicide dissipation in soil: the first-order kinetic and the non-linear empirical models. We used the non-linear empirical model assuming that the degradation rate of a herbicide in soil is proportional to the difference of the observed concentration of herbicide in soil at time and concentration of herbicide in the last day of measurement

New syntheses and ring expansion reactions of cyclobutenimines

Two routes are reported for the synthesis of iminocyclobutenones having N-(het)aryl substitution: an addition/substitution sequence starting with cyclobutenediones and an aza-Wittig method. A new synthetic route to N-alkyl derivatives is also presented. This involves O-alkylation of 3-alkylamino-1,2-cyclobutenediones using Meerwein's reagent and subsequent deprotonation under non-hydrolytic conditions. Lithium organyls were found to add to the remaining carbonyl group. The resulting tertiary alcohols undergo ring enlargement on heating in xylene to give 4-aminophenols, 4-amino-1-naphthols, or cyclopenta-annulated quinolines from 4-vinyl, 4-aryl, and 4-alkynyl derivatives, respectively. © CSIRO 2010

New syntheses and ring expansion reactions of cyclobutenimines

Two routes are reported for the synthesis of iminocyclobutenones having N-(het)aryl substitution: an addition/substitution sequence starting with cyclobutenediones and an aza-Wittig method. A new synthetic route to N-alkyl derivatives is also presented. This involves O-alkylation of 3-alkylamino-1,2-cyclobutenediones using Meerwein's reagent and subsequent deprotonation under non-hydrolytic conditions. Lithium organyls were found to add to the remaining carbonyl group. The resulting tertiary alcohols undergo ring enlargement on heating in xylene to give 4-aminophenols, 4-amino-1-naphthols, or cyclopenta-annulated quinolines from 4-vinyl, 4-aryl, and 4-alkynyl derivatives, respectively. © CSIRO 2010

ChemInform Abstract: 4-Iminocyclobutenones: Synthesis and Building-Blocks of Aminohydroquinones and Annulated Quinolines.

Two methods are presented for the synthesis of the title compounds starting from cyclobutenediones: an alkoxide substitution approach and a Staudinger reaction. Unsaturated lithiumorganyls may be added to the remaining carbonyl group and on heating lead to ring enlargement in a cascading process. 4-Alkenyl or 4-aryl derivatives yield aminophenols or -naphthols; 4-alkynyl compounds give cyclopenta-annulated quinolines. © Georg Thieme Verlag Stuttgart

4-iminocyclobutenones: Synthesis and building-blocks of aminohydroquinones and annulated quinolines

Two methods are presented for the synthesis of the title compounds starting from cyclobutenediones: an alkoxide substitution approach and a Staudinger reaction. Unsaturated lithiumorganyls may be added to the remaining carbonyl group and on heating lead to ring enlargement in a cascading process. 4-Alkenyl or 4-aryl derivatives yield aminophenols or -naphthols; 4-alkynyl compounds give cyclopenta-annulated quinolines. © Georg Thieme Verlag Stuttgart

Pharyngostomy tubes for gastric conduit decompression

ObjectiveThis article illustrates our operative technique for pharyngostomy tube placement and describes our clinical experience with pharyngostomy use for gastric conduit decompression after esophagectomy.MethodsWe retrospectively reviewed patients undergoing pharyngostomy tube placement for gastric conduit decompression after esophagectomy from January 2008 to August 2009. Patients were included if they had a pharyngostomy tube placed at esophagectomy (prophylactic placement) or as a means of decompression after postesophagectomy anastomotic leak (therapeutic placement). We collected operative and clinical data and performed a descriptive statistical analysis.ResultsWe placed 25 pharyngostomy tubes for gastric conduit decompression after esophagectomy. Eleven were placed prophylactically (44%); the remaining 14 were placed therapeutically (56%) after anastomotic leak. Prophylactic pharyngostomy tubes remained in place a median of 8 days (range 4–17 days), whereas therapeutic pharyngostomy tubes were left in place a median of 15 days (range 7–125 days). There were 4 infectious complications (16%) unrelated to length of pharyngostomy use: 2 cases of cellulitis (resolved with antibiotics, tube remaining in place) and 2 superficial abscesses after tube removal requiring bedside débridement. Seventy-two percent of patients underwent swallow evaluation; 22% of these patients had radiographic evidence of aspiration.ConclusionsPharyngostomy tube placement for gastric conduit decompression after esophagectomy is simple, and tubes can stay in place for prolonged periods. Our experience suggests that pharyngostomy tubes are a safe alternative to nasogastric drainage