NaSrMn2F7, NaCaFe2F7, and NaSrFe2F7: novel single crystal pyrochlore antiferromagnets.

The crystal structures and magnetic properties of three previously unreported A2B2F7 pyrochlore materials, NaSrMn2F7, NaCaFe2F7, and NaSrFe2F7 are presented. In these compounds, either S = 2Fe2+ or S = 5/2Mn2+ is on the B site, while nonmagnetic Na and Ca (Na and Sr) are disordered on the A site. The materials, which were grown as crystals via the floating zone method, display high effective magnetic moments and large Curie-Weiss thetas. Despite these characteristics, no ordering transition is detected. However, freezing of the magnetic spins, characterized by peaks in the susceptibility or specific heat, is observed at very low temperatures. The empirical frustration index, f = -θ CW/T f, for the materials are 36 (NaSrMn2F7), 27 (NaSrFe2F7), and 19 (NaCaFe2F7). AC susceptibility, DC susceptibility, and heat capacity measurements are used to characterize the observed spin glass behavior. The results suggest that the compounds are frustrated pyrochlore antiferromagnets with weak bond disorder. The magnetic phenomena that these fluoride pyrochlores exhibit, in addition to their availability as relatively large single crystals, make them promising candidates for the study of geometric magnetic frustration.

Effects of water accommodated fractions of crude oils and diesel on a suite of biomarkers in Atlantic cod (Gadus morhua).

The aim of this study was to characterize concentration- and time-dependent responses in juvenile Atlantic cod (Gadus morhua) following exposure for one and three weeks to the water-soluble fraction (WAF) of three weathered oils: Arabian Light crude oil (ALC), North Sea crude oil (NSC) and ship-diesel. The sum of polycyclic aromatic hydrocarbons (PAH) in water was highest after one week of exposure and within environmentally relevant concentrations. PAH metabolites in bile confirmed exposure to and uptake of PAHs. Hepatic cytochrome P450 1A (CYP1A) gene expression (mRNA quantification) increased dramatically following exposure to all three oil types (fold-change up to 165) and there was a time lag between gene and protein expression. Hepatic CYP1A protein concentration and ethoxyresorufin-O-deethylase (EROD) activity were more variable among individuals and treatments than gene expression. EROD activity in liver and gills increased in fish exposed to WAF from the two crude oils, but not in fish exposed to WAF from diesel. Exposure to diesel appeared to induce oxidative stress to a greater extent than exposure to crude oils. Other biomarkers (glutathione S-transferases, acetylcholine esterase, vitellogenin) did not appear to respond to the exposure and hence did not discriminate among oils. Biomarker responses in cod after exposure to weathered crude oils and diesel suggested that the CYP1A system and oxidative stress markers have the highest potential for discriminating among different oil types and to monitor the environmental consequences of spills.

Multiresidue analysis of beta-agonists in bovine and porcine urine, feed and hair using liquid chromatography electrospray ionisation tandem mass spectrometry.

The use of beta-agonists as growth promoters in cattle breeding is forbidden in many countries for reasons of fair trade and consumer protection. In recent years the use of liquid chromatography (LC) tandem mass spectrometry (MS/MS) has been shown to be the method of choice for the control of beta-agonists. In this study an LC-MS/MS multiresidue analysis method is presented for trace analysis of 22 beta-agonists. A truly generic concept has been designed based on mixed-mode solid-phase extraction and positive electrospray ionisation LC-MS/MS operated in the multiple reaction monitoring mode. This method allows application to a wide variety of sample matrices such as urine, feed and hair, following minor modifications to the analysis procedure only. The method features fit-for-purpose sensitivity in urine as shown by CCalpha and CCbeta values of less than 0.2 and less than 0.5 microg/l respectively, for all beta-agonists studied (terbutaline and reproterol, less than 0.3 and less than 1.0 respectively). Similar but semiquantitative application to feed and hair showed CCbeta values of less than 10.0 and less than 5.0 microg/kg, respectively. A further simplification and improvement is demonstrated using Ultra Performance LC (UPLC) and fast-switching MS/MS. The successful validation of this method following the latest EU requirements and its application to real samples demonstrate that a new versatile tool has been achieved for veterinary control of beta-agonists.

Screening for estrogen residues in calf urine: comparison of a validated yeast estrogen bioassay and gas chromatography-tandem mass spectrometry.

Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography-tandem mass spectrometry. Recently, we developed a robust yeast bioassay screening tool for estrogens, which was validated as a qualitative screening method in accordance with EC decision 2002/657/EC. In this study, we present long-term performance data and a comparison of urine data obtained with this bioassay, and data from an established gas chromatography-tandem mass spectrometry (GC/MS/MS) confirmatory analysis method. More than 120 calf urine samples from a controlled reference experiment were analysed using both protocols. According to the GC/MS/MS method, only the natural estrogens 17alpha-estradiol and estrone were present in the non-compliant samples. The bioassay was less sensitive than GC/MS/MS for the relatively weak estrogenic compound 17alpha-estradiol, in accordance with expectations. Assuming that application of the mass spectrometric method is considered beyond reasonable doubt, the bioassay performed very well: only 5.6% of the calf urine samples found compliant in GC/MS/MS were screened false suspect in the bioassay screening method. The bioassay results of non-compliant urine samples under routine conditions were as predicted, taking into account the relative estrogenicity of the natural estrogens 17alpha-estradiol and estrone vs. 17beta-estradiol. Only one sample was screened false negative for 17alpha-estradiol and estrone. Application of this fast and simple estrogen bioassay in routine surveillance and control can significantly reduce GC/MS/MS sample workload and allow higher percentages of animals to be screened for potential hormone abuse.

Prediction of swine carcass composition by total body electrical conductivity (TOBEC).

An experiment was conducted to determine prediction equations that used readings for total body electrical conductivity (TOBEC) in the model for estimation of total fat-free lean and total fat weight in the pork carcass. Ultrasound measurements of live hogs were used to select 32 gilts that represented a range in weight, muscling, and fatness. The TOBEC readings were recorded on warm carcass sides, chilled carcass sides, and the untrimmed ham from the left carcass side. Physical dissection and chemical analyses determined fat-free lean and fat weight of the carcass. All of the ham tissues were analyzed separately from the remainder of the carcass tissues to incorporate ham measurements for prediction of total fat-free lean and total fat weight in the entire carcass. Prediction equations were developed using stepwise regression procedures. An equation that used a warm carcass TOBEC reading in the model was determined to be the best warm TOBEC equation (R2 = 0.91; root mean square error = 0.81). A three-variable equation that used chilled carcass TOBEC reading, chilled carcass temperature, and carcass length in the model was determined to be the best chilled TOBEC equation (R2 = 0.93; root mean square error = 0.73). A four-variable equation that included chilled carcass side weight, untrimmed ham TOBEC reading, ham temperature, and fat thickness beneath the butt face of the ham in the model was determined to be the best equation overall (R2 = 0.95; root mean square error = 0.65). The TOBEC and the fat-free lean weight of the ham are excellent predictors of total carcass fat-free lean weight.

Precipitation of water-soluble contrast material (Gastrografin) in the stomach in a case of outlet obstruction.

Precipitation of water-soluble contrast material (Gastrografin) within the fundus of a man with gastric outlet obstruction is discussed. Precipitation can occur in a stomach with increased acidity; the resultant precipitate possibly causes mucosal irritation, erosion, and bleeding.