Synthesis and characterization of the nitrides of platinum and iridium     

Crowhurst JC  Goncharov AF  Sadigh B  Evans CL  Morrall PG  Ferreira JL  Nelson AJ 《Science (New York, N.Y.)》2006,311(5765):1275-1278

Transition metal nitrides are of great technological and fundamental importance because of their strength and durability and because of their useful optical, electronic, and magnetic properties. We have evaluated a recently synthesized platinum nitride (PtN) that was shown to have a large bulk modulus, and we propose a structure that is isostructural with pyrite and has the stoichiometry PtN2. We have also synthesized a recoverable nitride of iridium under nearly the same conditions of pressure and temperature as PtN2. Although it has the same stoichiometry, it exhibits much lower structural symmetry. Preliminary results suggest that the bulk modulus of this material is also very large.  相似文献   

Growth and Infestation by Hemlock Woolly Adelgid of Two Exotic Hemlock Species in a New England Forest     

Alexander M. Evans 《Journal of Sustainable Forestry》2013,32(3):223-240

ABSTRACT

The hemlock woolly adelgid (HWA, Adelges tsugae Annand) an invasive exotic insect, may extirpate eastern hemlock (Tsuga canadensis (L.) Carrière) trees from native forests, but other hemlock species could be planted to occupy their ecological niche. This study tests two of the most likely replacement species candidates: western hemlock (T. heterophylla (Raf.) Sargent) and Chinese hemlock (T. chinensis (Franchet) Pritzel). Low survival rates, slow growth, and infestation by HWA of western hemlock in eastern hemlock forests shows that the western hemlock is not a likely candidate for planting in the northern portion of eastern hemlock's range. In contrast, Chinese hemlock grew at rates similar to eastern hemlock and did not show any signs of HWA infestation. In this study, damage from deer was a much bigger problem than growth reductions from HWA.  相似文献   

Beef production from the dairy herd: An analysis of mortalities     

G.C. Everitt M.Sc. Ph.D. N.D.A. Dip.Agr.Sc.  S.T. Evans N.D.A. 《New Zealand veterinary journal》2013,61(7):132-139

Extract

Utilization of surplus dairy animals for beef production has made notable progress in the past 2 to 3 years. In 1967 over 75,000 calves were reared for beef, increasing to about 150,000 in 1968 and probably more than 200,000 in 1969. This reflects, in part, the economic problems involved in international marketing of dairy products, but, in greater part, the accumulation and dissemination of technical knowledge derived from recent experimental work.  相似文献   

Neospora abortion epidemic in a dairy herd     

R.N. Thornton  A. Gajadhar  J. Evans 《New Zealand veterinary journal》2013,61(5):190-191

Neospora caninrm is a protozoan closely related to Toxoplasma gonclii. It was discovered only a few years ago, but it is now recognised as one of the most common and important causes of abortion in cattle. Brain lesions characteristic of Neospora infection have been found in about 25% of aborted foetuses submitted to diagnostic laboratories in New Zealand and overseas⁽¹⁾⁽²⁾. Average abortion rates due to Neospora on New Zealand farms have been estimated at 7% of pregnancies compared with 4% due to other causes⁽¹⁾. The upper range of abortion rates for Neospora was 17–30% compared to only 7–10% for other causes, showing that the economic effects of Neospora abortions on the more severely affected farms can be devastating.  相似文献   

Tracing Dietary Mercury Histochemically,with Autometallography,through the Liver to the Ovaries and Spawned Eggs of the Spot,a Temperate Coastal Marine Fish     

John J. Govoni  James A. Morris Jr.  David W. Evans 《Journal of aquatic animal health》2013,25(3):173-180

Abstract

Exposure to mercury (Hg) results in reproductive abnormalities and deficiencies in female fish. We traced the maternal assimilation and redistribution of dietary inorganic (HgII) and organic (MeHg) forms of Hg in a coastal marine fish, the Spot Leiostomus xanthurus. We conducted a 90-d laboratory experiment in which treatment Spot were fed muscle of Blue Marlin Makaira nigricans with elevated concentrations of Hg mixed with a commercial fish food, while control Spot were fed only commercial food pellets. Gonadal maturation was induced by shortening the photoperiod and increasing the temperature. Spawning was induced by intramuscular injection of human chorionic gonadotropin at 100 IU/kg. Solid-sampling atomic absorption spectrophotometry measured the total Hg (THg), HgII, and MeHg in Blue Marlin muscle. Autometallography located Hg-sulfide granules in the liver, ovaries, and spawned eggs, and densitometry provided comparisons of Hg-sulfide granules in the ovaries of treatment and control Spot. Overall, the intensity and prevalence of Hg-sulfide granules were greater in the liver, ovaries, and eggs from treatment Spot than in those from controls. The tissue and cellular distribution of Hg-sulfide granules differed.

Received November 18, 2016; accepted June 18, 2017 Published online August 11, 2017  相似文献   

Enhancing Maize Grain Yield in Acid Soils of Western Kenya Using Aluminium Tolerant Germplasm     

Ouma Evans  Ligeyo Dickson  Matonyei Thomas  Agalo Joyce  Were Beatrice  Too Emily  OnkwareAugustino  Gudu Samuel  Kisinyo Peter  Philip Nyangweso 《农业科学与技术》2013,(1):33-46

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Habitat edge effects alter ant-guard protection against herbivory     

Daniel M. Evans  Nash E. Turley  Joshua J. Tewksbury 《Landscape Ecology》2013,28(9):1743-1754

Edge effects are among the most important drivers of species interactions in fragmented habitats, but the impacts of edge effects on multitrophic interactions are largely unknown. In this study we assess edge effects on species interactions within an ant–plant mutualistic system—where ants protect plants against herbivory—to determine whether habitat edges alter the amount of protection ants provide. We focus on a single species of myrmecophytic plant, Solanum americanum, and experimentally manipulate ant access to study plants in large-scale fragmented habitat patches at the Savannah River Site National Environmental Research Park, USA. In this system, S. americanum commonly hosts honeydew-producing aphids that are tended by ants, and grasshoppers are the primary herbivores. We measured edge effects on the per-plant abundance of aphids and protective ants as well as the abundance of grasshoppers in each habitat patch, and we evaluated levels of ant protection against herbivory near and far from habitat edges. We found that ants provided significant protection to plants far from edges, where herbivory pressure was highest, despite the fact that aphids and ants were least abundant on these plants. Conversely, ants did not provide significant protection near edges, where herbivory pressure was lowest and aphids and ants were most abundant. We conclude that a strong edge effect on grasshopper abundance was a key factor determining the amount of protection ants provided against herbivory. Future studies of the impacts of habitat fragmentation on ant–plant mutualisms will benefit from studies of ant behavior in response to herbivory threats, and studies of edge effects on other species interactions may also need to consider how species’ behavioral patterns influence the interactions in question.  相似文献   

Calcium metabolism in eight dogs with hypoadrenocorticism     

A. G. Gow    D. J. Gow    R. Bell    J. W. Simpson    M. L. Chandler    H. Evans    J. L. Berry    M. E. Herrtage    R. J. Mellanby 《The Journal of small animal practice》2009,50(8):426-430

Hypoadrenocorticism is a well-described endocrinopathy in dogs that results from deficient production and secretion of glucocorticoids and/or mineralocorticoids. Although hyperkalaemia, hyponatraemia and hypochloraemia are the most common electrolyte disturbances, hypercalcaemia also occurs in approximately 30 per cent of cases. The pathogenesis of hypercalcaemia in dogs with hypoadrenocorticism is unknown. This case series reports ionised calcium, parathyroid hormone, parathyroid hormone-related protein and vitamin D metabolite concentrations that were measured in eight dogs with concurrent hypercalcaemia and hypoadrenocorticism. Ionised calcium was increased in five of seven dogs with hypercalcaemia associated with hypoadrenocorticism. Parathyroid hormone, parathyroid hormone-related protein and 1,25 dihydroxyvitamin D concentrations were within their reference ranges in seven of eight dogs, six of seven cases and six of seven dogs, respectively. This case series highlights that hypercalcaemia associated with hypoadrenocorticism is rarely associated with increases in plasma parathyroid hormone, parathyroid hormone-related protein or serum 1,25 dihydroxyvitamin D concentrations.  相似文献   

世界禽蛋产业全景展望     

Terry Evans 《中国家禽》2009,31(15)

文章对四大洲的主要禽蛋生产和加工国家的近况进行了总结,并对未来的发展进行了展望,为该产业的发展提供借鉴.  相似文献   

Predictors of Australian consumers' intentions to consume conventional and novel sources of long-chain omega-3 fatty acids     

Cox DN  Evans G  Lease HJ 《Public health nutrition》2008,11(1):8-16

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