A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting     

O Khaselev  JA Turner 《Science (New York, N.Y.)》1998,280(5362):425-427

Direct water electrolysis was achieved with a novel, integrated, monolithic photoelectrochemical-photovoltaic design. This photoelectrochemical cell, which is voltage biased with an integrated photovoltaic device, splits water directly upon illumination; light is the only energy input. The hydrogen production efficiency of this system, based on the short-circuit current and the lower heating value of hydrogen, is 12.4 percent.  相似文献   

Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from crevice cave, missouri, USA   总被引：3，自引：0，他引：3  

JA Dorale  RL Edwards  E Ito  LA Gonzalez 《Science (New York, N.Y.)》1998,282(5395):1871-1874

Four Missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago (ka). The thorium-230-dated records reveal that between 75 and 55 ka, the midcontinental climate oscillated on millennial time scales between cold and warm, and vegetation alternated among forest, savanna, and prairie. Temperatures were highest and prairie vegetation peaked between 59 and 55 ka. Climate cooled and forest replaced grassland at 55 ka, when global ice sheets began to build during the early part of Marine Oxygen Isotope Stage 3.  相似文献   

A long-snouted predatory dinosaur from africa and the evolution of spinosaurids     

PC Sereno  AL Beck  DB Dutheil  B Gado  HCE Larsson  GH Lyon  JD Marcot  OWM Rauhut  RW Sadleir  CA Sidor  DD Varricchio  GP Wilson  JA Wilson 《Science (New York, N.Y.)》1998,282(5392):1298-1302

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.  相似文献   

Andover: An early to midseason golden nematode resistant variety for use as chipstock or tablestock     

R. L. Plaisted  D. E. Halseth  B. B. Brodie  S. A. Slack  J. B. Sieczka  B. J. Christ  K. M. Paddock  M. W. Peck 《American Journal of Potato Research》1998,75(3):113-116

Andover may be used as an early to midseason tablestock and chipstock variety. It has a very rapid emergence and early tuber set. The vine maturity is similar to Superior in the absence of severe stress. In New York trials harvested 90 days after planting, the yields of Andover and Superior are nearly equal, 274 cwt/A. At 120 days, over eight seasons at two Ithaca locations, Andover yielded 87% Atlantic. Andover appears to be susceptible to drought and heat stress which can cause early senescence and reduce late season yields. It has few external and internal defectS. Specific gravity is high for an early variety, being .009 less than Atlantic. Andover has excellent chip color from the field from a range of environments and from 7 C storage. It has good boiling and baking properties. The mealiness of the baked potatoes is especially good. Tuber dormancy is two weeks longer than Atlantic. The reaction to common scab is like that of Monona, which is considered to be resistant. It is also resistant to powdery scab and the golden nematode.  相似文献   

Resistance of potato to cucumber mosaic virus appears related to localization in inoculated leaves     

F. Celebi  P. Russo  K. Watanabe  J. P. T. Valkonen  S. A. Slack 《American Journal of Potato Research》1998,75(4):195-199

Although CMV can cause extensive damage to solanaceous crops like tomato, tobacco and pepper, it has little if any impact on the related crop, potato. To better understand this phenomenon, we have tested 32 potato genotypes for susceptibility or resistance to local and systemic Fny-CMV infection. Using ELISA, all genotypes appeared to show virus replication in leaves that were mechanically inoculated. In contrast, only ten genotypes exhibited systemic spread as expressed by significant CMV titers in new growth. These data suggest that, although CMV can replicate in potato cells and appears to spread short distances cell-to-cell, long distance movement appears to be blocked in most potato genotypes. Therefore, the general resistance of potato crops to CMV infection may be related to virus localization at points of entry.  相似文献   

Impact of transgenic viral resistance on seed potato certification     

Steven A. Slack  Thomas L. German 《American Journal of Potato Research》1998,75(6):265-268

It was nearly 100 years ago that the decline in quality and yield observed in potato crops was attributed to the accumulation of pathogens in seed tubers saved from one field generation to the next. As a direct result of this realization, seed potato certification programs have been initiated throughout the world. While these programs have different administrative structures and employ various methodologies, they are all dedicated to the primary goal of producing a sufficient volume of high quality seed tubers as free from disease causing organisms as possible. Viral diseases are especially problematic because they have serious economic affects and their physical and biological properties make them difficult to control. Until recently, certification programs have relied on methodologies including the use of virus-free material obtained from tissue culture, strict adherence to practices that minimize the mechanical and insect spread of virus, physical inspection of seed increase plots to identify and minimize the number of virus-infected plants, and the increase of seed materials for only a limited number of years to insure that any infected materials are “flushed out” of the system. Approximately 10 years ago, it was first observed that virus resistance can be obtained by using transformation techniques to insert viral genes into the genome of plants. Subsequently, researchers in private and public laboratories have shown that potato plants produced in this way are highly resistant or immune to several viral diseases. The effect that the deployment of these materials may have on the seed potato certification process is the subject of this paper.  相似文献   

Priming of cowpea volatile emissions with defense inducers enhances the plant's attractiveness to parasitoids when attacked by caterpillars          下载免费PDF全文

Toby JA Bruce  Ted CJ Turlings 《Pest management science》2018,74(4):966-977

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Transduction and Transplantation of Spermatogonia into the Testis of Ram Lambs through the Extra-testicular Rete     

JR Rodriguez-Sosa  JD Silvertown  RA Foster  JA Medin  A Hahnel 《Reproduction in domestic animals》2009,44(4):612-620

Spermatogonial transplantation will provide a new way to study spermatogenesis in domestic animals, disseminate male genetics and produce transgenic animals, if efficiency can be improved. We evaluated a 'surgical' method for transplanting donor cells into testes of ram lambs, where the head of the epididymis is reflected, and a catheter introduced into the extra-testicular rete testis. We also tested transduction of ram spermatogonia with a lentiviral (LV) vector as a means to identify permanent colonization, and introduce genes into donor cells. Eight ram lambs, 11- to 13-week olds, were the recipients: in five, spermatogonia were injected into one testis, and the contralateral testis was an un-manipulated control: in two, spermatogonia were injected into one testis and the contralateral was sham-injected: in one, both testes were injected. Six lambs received spermatogonia labelled with a cell-tracking dye and these were collected 1 or 2 weeks after transplantation; three lambs received spermatogonia transduced with a LV vector driving the expression of enhanced Green Fluorescence Protein and these were collected after 2 months. Donor cells were detected by immunohistochemistry in tubules of seven of nine recipient testes. Approximately 22% of tubule cross-sections contained donor cells immediately after transplantation, and 0.2% contained virally transduced cells 2 months after transplantation. The onset of spermatogenesis was delayed, and there were lesions in both injected and sham-injected testes. Despite the effects of the surgery, elongated spermatids were present in one recipient testis 2 months after surgery. The results suggest that, after modifying the surgical and transduction techniques, this approach will be a means to produce good colonization by donor spermatogonia in sheep testes.  相似文献   

Hyperoxaluria,hyperglycoluria and renal oxalosis in Gilbert's potoroos (Potorous gilbertii)          下载免费PDF全文

D Forshaw  AM Horwitz  K Ellard  JA Friend  L Greed  M Metz 《Australian veterinary journal》2017,95(7):250-258

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Lamprey GnRH‐III Releases Luteinizing Hormone but not Follicle Stimulating Hormone in Pigs     

R Barretero‐Hernandez  JA Vizcarra  A Bowen  M Galyean 《Reproduction in domestic animals》2010,45(6):983-987

The effect of exogenous administration of lamprey GnRH‐III (IGnRH‐III) on gonadotropin secretion was evaluated in pigs. Six crossbred barrows (82.4 ± 3.5 kg body weight) were assigned randomly to a replicated 3 × 3 Latin square design to evaluate the effect of 0.1, 1.0 or 10.0 μg/kg body weight of exogenous IGnRH‐III on LH and FSH secretion. To facilitate blood collection and infusion of IGnRH‐III, barrows were catheterized in the jugular vein 1 day before initiation of experiments. Blood samples were taken at 10‐min intervals for 6 h, starting 2 h before treatments were applied. Relative concentrations of LH and FSH were calculated by obtaining the ratio of the average concentration of each hormone 2 h after infusion divided by the average concentration during the 2 h before infusion. Relative concentrations of FSH after IGnRH‐III infusion did not influence mean concentration of FSH at any of the doses; yet 10.0 μg/kg body weight had a significant effect on LH secretion (p < 0.01). Relative concentrations of LH averaged 1.2, 1.0 and 3.0 ng/ml (for doses of 0.1, 1.0 and 10.0 μg/kg body weight of IGnRH‐III respectively). Only a dose of 10 μg/kg body weight elicited a significant LH increase that was associated with exogenous IGnRH‐III infusion. We conclude that IGnRH‐III is a weak GnRH agonist and at high doses, IGnRH‐III has the ability to release LH but not FSH in barrows.  相似文献