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The tetragonal DO22 phase of the Mn3-xGa compounds, with x varying from 0 to 1.15, has been successfully synthesized by annealing the ingots with the cubic γ-phase. It is found that the lattice parameter a of the tetragonal cell remains almost constant, while the lattice parameter c increases significantly as x varies from 0 to 1.15. In the meantime, the magnetization of Mn3-xGa (at 7 T) increases dramatically with increasing x. A substitution model, which is different to the model with manganese vacancies, is proposed to explain these changes. According to this model, the increase of the lattice parameter c and the magnetization with x can be explained by an assumption that Mn atoms at 2b sites are preferentially substituted by larger and nonmagnetic Ga atoms. A coercivity which is higher than that of other bulk Mn3-xGa alloys ever reported is achieved. Coercivities as large as iHc=21.4 kOe and 18.2 kOe are obtained for Mn3.0Ga at 5K and 300 K, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the magnetic properties of MnBi compound, anisotropic MnBi/Sm2Fe17Nx hybrid magnet was prepared by grinding of high purity MnBi ribbons and Sm2Fe17Nx particles together. The smooth hysteresis loops of the hybrid magnets indicated that the mixture of the hard/hard phase magnetic components was well exchange coupled. As compared to the single MnBi phase magnet, the remanent magnetization and maximum energy product (BH)max of the composited magnets were improved. As an optimized result, the exchange coupled magnet of MnBi/Sm2Fe17Nx=3/7 yielded both high remanence and coercivity from 250K to 380 K. A maximum energy product (BH)max of 18 MGOe was achieved at 300 K, and remained 10 MGOe at 380 K, implying the MnBi/Sm2Fe17Nx magnets can be specially utilized in the high temperature environment. [ABSTRACT FROM AUTHOR]

The crystallographic structural and magnetic properties of polycrystalline La0.7Sr0.3Mn1–xCoxO3 ( x=0.4 , 0.5, 0.6, 1.0) have been systematically studied in detail by neutron powder diffraction and magnetic measurements. The introduction of Co dopant to the Mn network has decreased the bandwidth ( W ) and the overlap between the O- 2p and the Mn- 3d orbitals. In addition, it in turn weakened the fragile double exchange coupling of Mn3+–O–Mn4+ and reduced the magnetization M . The magnetic measurements indicate the presence of mixed magnetic phases in this system. When the temperature is above Tc , the jump of field-dependent magnetization disappeared, which is related to the competition of ferromagnetic and antiferromagnetic interactions. The average atom magnetization extracted from M – H curve at 5 K using the approach-to-saturation method, is \sim 1.70~\mu _{\mathrm {B}} /Co for La0.7Sr0.3CoO3. This value approaches to the neutron refined data 1.93(8) \mu _{\mathrm {B}}$ . However, as for x = 0.4$ , x = 0.5$ and 0.6 samples, the calculated data from magnetization at 5 T are all smaller than the refined one, due to the existence of spin-glass-like phase. The weak magnetic peaks are responsible for the small magnetic moment data ( for LSMO–Co0.5 and 0.65~\mu _{\mathrm {B}} for LSMO–Co0.6). These results indicate the competing magnetic interactions in the system of La0.7Sr0.3Mn1–xCoxO3 compounds. [ABSTRACT FROM AUTHOR]

In this paper, high purity τ-Mn54Al46 and Mn54-xAl46Cx alloys were successfully prepared using conventional arc-melting, melt-spinning, and heat treatment process. The magnetic and the structural properties were examined using x-ray diffraction (XRD), powder neutron diffraction and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm-1, coercivity of 0.5 T, and a maximum energy product of (BH)max = 24.7 kJm-3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54-xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon-free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 μβ which results from strong hybridization between Mn-Al and Mn-Mn. We also investigated the volume and c/a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra-atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 μβ at a volume expansion rate of ΔV/V≈ 20%. [ABSTRACT FROM AUTHOR]

The magnetic and microwave absorption properties of the interstitial atom modified intermetallic compound Ce2Fe17NX have been investigated. The Ce2Fe17NX compound shows a planar anisotropy with saturation magnetization of 1088 kA/m at room temperature. The Ce2Fe17NX paraffin composite with a mass ratio of 1:1 exhibits a permeability of μ' = 2.7 at low frequency, together with a reflection loss of - 26 dB at 6.9 GHz with a thickness of 1.5 mm and - 60 dB at 2.2 GHz with a thickness of 4.0 mm. It was found that this composite increases the Snoek limit and exhibits both high working frequency and permeability due to its high saturation magnetization and high ratio of the c-axis anisotropy field to the basal plane anisotropy field. Hence, it is possible that this composite can be used as a high-performance thin layer microwave absorber. [ABSTRACT FROM AUTHOR]

A special kind of asymmetric magnetization reversal characterized by a sharp step in the second quadrant of the hysteresis loop has been investigated in the exchange biased Co/CoO films. This asymmetry only exists in the film where the small clusters grow to form islands. A bimodal distribution of the first-order reversal curves diagram demonstrates that the irreversible magnetization reversal is composed of the free part and exchange biased part, originating from the grains smaller and larger than 6 nm in the film, respectively. The finite-size effect of the antiferromagnetic anisotropy in the ultrafine grains is responsible for this asymmetry. [ABSTRACT FROM AUTHOR]

Compounds with nominal compositions Sm10Fe90 and Sm10Fe90Ti2B were prepared by strip casting method. Disordered Th2Zn17-type phase of Sm10Fe90Ti2B was achieved. This disordered Th2Zn17 (space group R-3m) phase was formed by randomly replacing Sm(3a) with Fe(6c)-dumbbell ((3a) and (6c) are Wyckoff symbols)). Scanning electron microscopy image revealed that the disordered Sm10Fe90Ti2B crystallized in micron-scaled grains, which is useful for the improvement of its hard magnetic properties. By annealing this disordered phase, it transformed into ordered rhombohedral Th2Zn17 structure. This derivative 2:17 type compound was further nitrided and then finely pulverized using surfactant-assisted grinding method. The final anisotropy powders showed excellent hard magnetic properties with coercivity of 12.4 kOe and (BH)max\sim 37\ MGOe. [ABSTRACT FROM AUTHOR]

Ni50Mn37Sn13 ribbons were produced by the melt-spinning method. Structure and magnetic measurements on the Ni50Mn37Sn13 ribbons indicated that it is ferromagnetic below 340 K and undergoes an austenitic-to-martensitic phase transition just below room temperature. The austenitic phase has the cubic L21 structure, with the excess manganese atoms occupying the 4(b) sites. The martensitic phase has an orthorhombic structure. With increasing applied magnetic field, the martensite start temperature Ms and martensite finish temperature Mf shift to lower temperatures because of the field-induced phase transition. The exchange-bias effect is observed and strongly varied with different cooling fields at low temperature. At 5 K, the exchange-bias field reaches a maximum of 290 Oe when the cooling field increases to 200 Oe, and then reduces sluggishly with further increase of the cooling field because of weakening of exchange coupling between antiferromagnetic and ferromagnetic interfaces. [ABSTRACT FROM AUTHOR]

MnBi with low temperature phase was fabricated by melt-spinning and subsequently annealing. The influence of quenching speeds, compositions and annealing conditions on the formation of low temperature phase MnBi was systematically investigated. It was found the amorphous MnBi ribbons could transform into low temperature phase by heat treatment in a temperature range of 533-593 K. The coercivity of MnBi was greatly improved by porphyrization, and exhibited a positive temperature coefficient. The maximum energy product BHmax of the anisotropic bonded magnet is 7.1 MGOe (56 kJ/m3) and 4.0 MGOe (32 kJ/m3) at room temperature and 400 K. [ABSTRACT FROM AUTHOR]

The influences of F-strain Mycoplasma gallisepticum (FMG) vaccine inoculation during the pullet period on the subsequent productive and reproductive performance of parent broiler chicken breeders on a multi-age farm were evaluated. Three thousand breeders were randomly divided into 2 treatment groups that were either vaccinated with FMG (FMG-vaccinated group) or not vaccinated with FMG (FMG-free group). Body weight and egg production were determined through approximately 50 wk of age. Egg weight and feed conversion was determined at 26, 32, 35, 38, and 43 wk of age. Egg quality parameters, including eggshell strength, egg-specific gravity, egg shape index, blood-meat spots, Haugh unit score, eggshell thickness, yolk:albumen ratio, percentage yolk, albumen and eggshell weights, and percentage fertility, hatchability, and second-quality chicks were determined at 26, 32, and 43 wk of age. Air sacs were examined and lesions were scored at 20, 32, and 50 wk of age. The number of mature ovarian follicles, histologies of ovary, and lengths, and histologies of the infundibulum, magnum, isthmus, uterus, and vagina were determined. In the present study, an increase in egg production of broiler breeder hens in the FMG-vaccinated group during peak of lay was compared with the FMG-free group. Feed conversion of hens in the FMG-vaccinated group was significantly less at 32, 35, 38, and 43 wk of age. Eggs from hens in the FMG-vaccinated group had a significantly higher Haugh units score at 26 wk of age and had a significantly higher eggshell thickness and lower incidence of blood-meat spots at 32 wk. Hatching eggs from hens in the FMG-vaccinated group had a significantly higher hatchability. The mean lesion score of air-sac lesion of birds in the FMG-vaccinated group was significantly less than FMG-vaccinated group. Uteruses of hens in the FMG-vaccinated group had a significantly longer length compared with the FMG-free group at 32 wk of age. The results indicate that inoculation of commercial parent broiler chicken breeders with the FMG vaccine before laying may prevent infection by field M. gallisepticum, and facilitate productive and reproductive performance. [ABSTRACT FROM AUTHOR]

Background: Synovial fluid components, especially lipids, can trigger oxidation of ultrahigh-molecular-weight polyethylene (UHMWPE) artificial joint components in vivo. The use of antioxidants such as vitamin E effectively diminishes the oxidative cascade by capturing free radicals and reducing the oxidation potential of UHMWPE implants. Using a thermo-oxidative aging method, we recently found that tea polyphenols can enhance the oxidation resistance of irradiated UHMWPE in comparison with commercial vitamin E. However, it is yet unknown whether tea polyphenols can reduce lipid-induced oxidation., Questions/purposes: We explored whether tea polyphenol-stabilized UHMWPE would exhibit (1) lower squalene absorption; (2) stronger oxidation resistance; and (3) lower content of free radicals than vitamin E-stabilized UHMWPE under a physiologically-motivated in vitro accelerated-aging model., Methods: Tea polyphenol (lipid-soluble epigallocatechin gallate [lsEGCG]) and vitamin E were blended with UHMWPE powders followed by compression molding and electron beam irradiation at 100 and 150 kGy. Small cubes (n = 3, 60 mg, 4 × 4 × 4 mm) cut from the blocks were doped in squalene at 60°, 80°, 100°, and 120° C for 2 hours. Gravimetric change of the cubes after squalene immersion was measured to assess absorption. Thin films (n = 3, ∼60 μm) were also microtomed from the blocks and were doped at 120° C for 24 hours. Oxidation induction time (n = 3, 5 mg of material from the cubes) and incipient oxidation temperature (n = 3, thin films) were obtained to determine the oxidation stability. Signal intensity of the free radicals, obtained by electron spin resonance spectroscopy, was used to qualitatively rank the antioxidant ability of vitamin E and lsEGCG., Results: Squalene absorption was comparable between lsEGCG/UHMWPE and vitamin E/UHMWPE at a given temperature and radiation dose. The oxidation induction time of 100 kGy-irradiated UHMWPE was increased with lsEGCG compared with vitamin E except at 120° C. For example, the oxidation induction time value of 100 kGy-irradiated lsEGCG/UHMWPE immersed at 60 C was 25.3 minutes (24.2-27.8 minutes), which was 8.3 minutes longer than that of 100 kGy-irradiated vitamin E/UHMWPE which was 17.0 minutes (15.0-17.1 minutes) (p = 0.040). After squalene immersion at 120° C, the incipient oxidation temperature of 100 and 150 kGy irradiated lsEGCG/UHMWPE was 234° C (227-240° C) and 227° C (225-229° C), which was higher than vitamin E-stabilized counterparts with value of 217° C (214-229° C; p = 0.095) and 216° C (207-218° C; p = 0.040), respectively. The electron spin resonance signal of 150 kGy irradiated lsEGCG/UHMWPE was qualitatively weaker than that of 150 kGy irradiated vitamin E/UHMWPE., Conclusions: lsEGCG-stabilized UHMWPE demonstrated higher oxidation resistance than vitamin E-stabilized UHMWPE after squalene immersion, likely because lsEGCG donates more protons to eliminate macroradicals than vitamin E., Clinical Relevance: Our in vitro findings provide support that lsEGCG may be effective in protecting against oxidation that may be associated with synovial fluid-associated oxidation of highly crosslinked UHMWPE joint replacement components.

Fructan plays an important role as an alternate carbohydrate and may contribute to drought and cold-stress tolerances in various plant species. The gene coding for sucrose:fructan 6-fructosyltransferase (6-SFT; EC 2.4.1.10), an enzyme that catalyzes the formation and extension of beta-2,6-linked fructans (levans), is important to fructan synthesis in many cool-season grasses, including cereal species. In this study, we compared a conserved sequence from the 6-SFT gene in barley with comparable sequences in 20 other cool-season grasses. We detected several DNA length polymorphisms, including variations in one simple-sequence repeat (SSR) in a 6-SFT intron of the barley cultivars Steptoe and Morex. Using the 'Steptoe' x 'Morex' doubled-haploid mapping population, the 6-SFT gene was genetically mapped to the distal region in the short arm of barley chromosome 1 (7H), where it is closely linked with trait locus Rpg1. Primers designed from other conserved regions of the barley 6-SFT gene successfully amplified 351- or 354-bp sequences of this gene from diverse cool season grass species. Sequence identities of the PCR products were greater than 80% among the 21 species. Phylogeny, as determined using these DNA sequences, is similar to that obtained from rDNA ITS sequences, and congruent with our current knowledge of genome relationships.

Genomes of Triticeae were analyzed using PCR with synthesized primers that were based on two published repetitive DNA sequences, pLeUCD2 (pLe2) and 1-E6hcII-1 (L02368),which were originally isolated from Thinopyrum elongatum. The various genomes produced a 2240 bp PCR product having high homology with the repetitive DNA pLe2. The PCR fragments produced from different genomes differed mainly in amplification quantity and in base composition at 89 variable sites. On the other hand, amplification products from the primer set for L02368 were of different sizes and nucleotide sequences. These results show that the two repetitive DNA sequences have different evolutionary significance. ple2 is present in all genomes tested, although differences in copy number and nucleotide sequence are notable. L02368 is more genome specific, i.e., fewer genomes possess this family of repetitive sequences. It was concluded that the repetitive sequence pLe2 family is an ancient one that existed in progenitor genome prior to divergence of annual and perennial genomes. In contrast, sequences similar to L02368 have only evolved following genome divergence.

Ten accessions of Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), collected from different geographical regions were analyzed using the C-banding technique. C-banding pattern polymorphisms were observed at all levels, i.e., within homologous chromosome pairs of the same plant, among different individuals within accessions, between different accessions of the same geographic area, and among accessions of different origins. The seven homologous groups varied in the level of C-banding pattern polymorphism; chromosomes A, B, E, and F were more variable than chromosomes C, D, and G. The polymorphisms did not hamper chromosome identification in Ps. juncea, because each chromosome pair of the Ns genome had a different basic C-banding pattern and karyotypic character. A standard C-banded karyotype of Ps. juncea is proposed based on the overall karyotypes and C-bands in the 10 accessions. The C-bands on the Ns-genome chromosomes were designated according to the rules of nomenclature used in wheat. A deletion-translocation heterozygote of Russian wildrye was identified based on the karyotype and C-banding patterns established. The chromosome F pair consisted of a chromosome having the distal segment in the long arm deleted and a translocated chromosome having the distal segment of long arm replaced by the distal segment of the long arm of chromosome E. The chromosome E pair had a normal chromosome E and a translocated chromosome having the short arm and the proximal segment of the long arm of chromosome E and the distal segment of the long arm of chromosome F.

Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), is an important forage grass and a potential source of germplasm for cereal crop improvement. Because of genetic heterogeneity as a result of its self-incompatibility, it is difficult to identify trisomics of this diploid species based on morphological characters alone. Putative trisomies (2n = 2x + 1 = 15), derived from open pollination of a triploid plant by pollen grains of diploid plants, were characterized by Giemsa C-banding. Based on both karyotypic criteria and C-banding patterns, four of the seven possible primary trisomics, a double-deletion trisomic, and two tertiary trisomics were identified.

Eight different genomes (E, H, I, P, R, St, W, and Ns) represented by 22 diploid species of the tribe Triticeae were analyzed using the random amplified polymorphic DNA (RAPD) technique. The genome relationships were obtained based on 371 RAPD fragments produced with 30 primers. The four species of the genus Psathyrostachys (having various Ns genomes) were closely related. The genomes Ee and Eb had a similarly close relationship and were distinct from all other genomes analyzed. Genomes P, R, and St were grouped in one cluster and genomes H and I in another. Genome W had a distant relationship with all other genomes. These results agree with the conclusions from studies of chromosome pairing and isozyme and DNA sequence analyses. Twenty-nine and 11 RAPD fragments are considered to be genome- and species-specific markers, respectively. One to six genome-specific markers were identified for each genome. These RAPD markers are useful in studies of genome evolution, analysis of genome composition, and genome identification.