Entropy Driven Dimerization in a One-Dimensional Spin-Orbital Model

We study a new version of the one-dimensional spin-orbital model with spins S=1 relevant to cubic vanadates. At small Hund's coupling J_H we discover dimerization in a pure electronic system solely due to a dynamical spin-orbital coupling. Above a critical value J_H, a uniform ferromagnetic state is stabilized at zero temperature. More surprisingly, we observe a temperature driven dimerization of the ferrochain, which occurs due to a large entropy released by dimer states. This dynamical dimerization seems to be the mechanism driving the peculiar intermediate phase of YVO_3.Comment: 5 pages, 4 figure

Evaluation of headspace Solid Phase Micro-extraction method for analysis of phosphine residues in wheat

This new method utilizes headspace-solid-phase micro extraction (HS-SPME) for pre-concentration of PH3. Phosphine was determined with gas chromatography/pulsed flame photometric detector (PFPD). Spiked samples were used for calculation of phosphine residue in grain. Four types of fibres (100μm-PDMS, 85μm- CAR/PDMS, 75μm-CAR/PDMS and 65μm-PDMS/DVB) were tested. The bipolar fibres (CAR/PDMS and PDMS/DVB) can extract PH3, but the non-polar fibre (PDMS) did not. Larger size fibres extracted PH3 more efficiently than the smaller size fibres (e.g., 85 μm > 75 μm > 65 μm). The 85μm CAR/PDMS fibre was used to optimize the different parameters that affect the SPME extraction efficiency of PH3. In the validation study, 50 grams of wheat in a 250 mL glass flask and capped with an open-top screw cap and PTFE/Silicon septa were spiked at 0.02 ng PH3/g of wheat. The flask was then heated to 45°C in an oil bath for 45 min, after which time the 85 μm CAR/PDMS fibre was exposed for 20 min and then exposed in the heated injection port of a GC/PFPD and desorbed for 2 min. Under conditions of the validation study, the limit of detection (LOD) or level of quantification (LOQ) was in the range of 0.005–0.01 ng PH3/g of wheat. Keywords: Fumigant, Phosphine, Residue, SPME, HS-SPM

Evaluation of headspace Solid Phase Micro-extraction method for analysis of phosphine residues in wheat

This new method utilizes headspace-solid-phase micro extraction (HS-SPME) for pre-concentration of PH3. Phosphine was determined with gas chromatography/pulsed flame photometric detector (PFPD). Spiked samples were used for calculation of phosphine residue in grain. Four types of fibres (100μm-PDMS, 85μm- CAR/PDMS, 75μm-CAR/PDMS and 65μm-PDMS/DVB) were tested. The bipolar fibres (CAR/PDMS and PDMS/DVB) can extract PH3, but the non-polar fibre (PDMS) did not. Larger size fibres extracted PH3 more efficiently than the smaller size fibres (e.g., 85 μm > 75 μm > 65 μm). The 85μm CAR/PDMS fibre was used to optimize the different parameters that affect the SPME extraction efficiency of PH3. In the validation study, 50 grams of wheat in a 250 mL glass flask and capped with an open-top screw cap and PTFE/Silicon septa were spiked at 0.02 ng PH3/g of wheat. The flask was then heated to 45°C in an oil bath for 45 min, after which time the 85 μm CAR/PDMS fibre was exposed for 20 min and then exposed in the heated injection port of a GC/PFPD and desorbed for 2 min. Under conditions of the validation study, the limit of detection (LOD) or level of quantification (LOQ) was in the range of 0.005–0.01 ng PH3/g of wheat. Keywords: Fumigant, Phosphine, Residue, SPME, HS-SPM

Large exchange bias after zero-field cooling from an unmagnetized state

Exchange bias (EB) is usually observed in systems with interface between different magnetic phases after field cooling. Here we report an unusual phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after zero-field cooling from an unmagnetized state. We propose this is related to the newly formed interface between different magnetic phases during the initial magnetization process. The magnetic unidirectional anisotropy, which is the origin of EB effect, can be created isothermally below the blocking temperature.Comment: including supplementary information, Accepted by Physical Review Letter

A genome scan for quantitative trait loci affecting male reproductive traits in a White Duroc × Chinese Erhualian resource population

Chinese Erhualian boars have dramatically smaller testes, greater concentrations of circulating androgens, and fewer Sertoli cells than Western commercial breeds. To identify QTL for boar reproductive traits, testicular weight, epididymal weight, seminiferous tubular diameter at 90 and 300 d, and serum testosterone concentration at 300 d were measured in 347 F2 boars from a White Duroc × Chinese Erhualian cross. A whole genome scan was performed with 183 microsatellites covering 19 porcine chromosomes. A total of 16 QTL were identified on 9 chromosomes, including 1% genome-wide significant QTL for testicular weight at 90 and 300 d and seminiferous tubular diameter at 90 d on SSCX, and for epididymal weight and testosterone concentration at 300 d on SSC7. Two 5% genome-wide significant QTL were detected for testicular weight at 300 d on SSC1 and seminiferous tubular diameter at 300 d on SSC16. Nine suggestive QTL were found on SSC1, 2, 3, 5, 7, 13, and 14. Chinese Erhualian alleles were not systematically favorable for greater reproductive performance. This study confirmed the previous significant QTL for testicular weight on SSCX and for epididymal weight on SSC7, and reported QTL for seminiferous tubular diameter and testosterone concentration at the first time. The observed different QTL for the same trait at different ages reflect the involvement of distinct genes in the development of male reproductive traits