Materials with negative compressibilities in one or more dimensions     

RH Baughman  S Stafstrom  C Cui  SO Dantas 《Science (New York, N.Y.)》1998,279(5356):1522-1524

Rare crystal phases that expand in one or more dimensions when hydrostatically compressed are identified and shown to have negative Poisson's ratios. Some of these crystals (i) decrease volume and expand in two dimensions when stretched in a particular direction and (ii) increase surface area when hydrostatically compressed. Possible mechanisms for achieving such negative linear and area compressibilities are described for single crystals and composites, and sensor applications are proposed. Materials with these properties may be used to fabricate porous solids that either expand in all directions when hydrostatically compressed with a penetrating fluid or behave as if they are incompressible.  相似文献   

Development of a Yersinia entomophaga bait for control of larvae of the porina moth (Wiseana spp.), a pest of New Zealand improved grassland systems     

Mark RH Hurst  Jayanthi Swaminathan  David A Wright  Scott Hardwick  Colin M Ferguson  Amy Beattie  Nicola K Richards  Lincoln Harper  Ray A Moss  Vanessa M Cave  Chikako van Koten  Mark R McNeill 《Pest management science》2020,76(1):350-359

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The effect of some cryoprotectants on dromedary camel frozen‐thawed semen          下载免费PDF全文

DA El‐Badry  RH Mohamed  HA EL‐Metwally  TR Abo Al‐Naga 《Reproduction in domestic animals》2017,52(3):522-525

The cryopreserved camel semen is often associated with poor quality and fertility. This study aimed to improve the dromedary frozen semen quality by comparing the efficiency of four cryoprotectant agents (CPAs) on sperm freezability. Semen samples were collected from seven male Maghrabi camels, diluted with Shotor diluent supplemented with glycerol (Sh‐G), dimethyl formamide (DMF, Sh‐DF), dimethyl sulfoxide (DMSO, Sh‐DS) or ethylene glycol (EG, Sh‐EG), all at 6% final concentration, and the samples were subjected to cryopreservation. The results revealed the superiority of Sh‐DF over Sh‐G and Sh‐DS in terms of post‐thaw motility (55.83 ± 2.20 vs. 47.50 ± 4.33 and 45.00 ± 2.89%, respectively), sperm membrane (49.00 ± 0.58, 39.33 ± 3.33 and 42.67 ± 1.45%, respectively) and acrosomal integrities (53.00 ± 0.58, 57.33 ± 0.88 and 52.33 ± 1.45%, respectively). Sh‐EG group showed the lowest post‐thaw motility, plasma membrane and acrosome integrities (12.50 ± 1.44, 22.67 ± 1.45 and 30.67 ± 1.45, respectively). In conclusion, the protocols of dromedary camel semen cryopreservation could be enhanced using 6% DMF as a cryoprotectant agent.  相似文献   

Seroprevalence and risk factors for Toxoplasma gondii infection in domestic cats in The Netherlands     

Opsteegh M  Haveman R  Swart AN  Mensink-Beerepoot ME  Hofhuis A  Langelaar MF  van der Giessen JW 《Preventive veterinary medicine》2012,104(3-4):317-326

Cats, as definitive hosts, play an important role in the transmission of Toxoplasma gondii. To determine the seroprevalence and risk factors for T. gondii infection in Dutch domestic cats, serum samples of 450 cats were tested for T. gondii antibodies by indirect ELISA. Binary mixture analysis was used to estimate the seroprevalence, the optimal cut-off value and the probability of being positive for each cat. The seroprevalence was estimated at 18.2% (95% CI: 16.6-20.0%) and showed a decrease with age in very young cats, an increase up to about 4 years old and ranged between 20 and 30% thereafter. Hunting (OR 4.1), presence of a dog in the household (OR 2.1), former stray cat (OR 3.3) and feeding of raw meat (OR 2.7) were identified as risk factors by multivariable logistic regression analysis. Prevalence differences were estimated by linear regression on the probabilities of being positive and used to calculate the population attributable fractions for each risk factor. Hunting contributed most to the T. gondii seroprevalence in the sampled population (35%).  相似文献   

Effect of foot paring of sheep affected with footrot on response to zinc sulphatehodium lauryl sulphate foot bathing treatment     

RH CASEY  PAJ MARTIN 《Australian veterinary journal》1988,65(8):258-259

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An epidemiological study of sheep deaths before and during export by sea from Western Australia     

RT NORRIS  RB RICHARDS  RH DUNLOP† 《Australian veterinary journal》1989,66(9):276-279

A study was conducted to record the deaths that occurred during export, and to examine the temporal pattern of pellet feeding in the feedlot and ascertain the variation in mortality between groups of sheep from different farms. Between November 1985 and April 1987, 5 cohorts of sheep were selected on arrival at a feedlot before live export by sea from Western Australia to the Middle East. Each cohort consisted of 4,118 to 9,612 Merino wethers from 15 to 35 farms (lines). There were few deaths during trucking to the feedlot (rate 0.9, range 0.0 to 3.0 per 10,000 sheep) and during lot-feeding (rate 6.2, range 1.2 to 12.2 per 10,000 sheep). Most of the deaths occurred aboard ship (rate 210.7, range 152.7 to 271.5 per 10,000 sheep). The proportion of sheep that ate pelleted feed increased with increasing length of time in the feedlot. By the end of lot-feeding the percentage of sheep that had not eaten pellets was 23.3, 4.4, 1.2, 2.1 and 0.2 in a representative sample of each of the 5 cohorts. It was considered that offering hay throughout lot-feeding was undesirable for the purpose of maximising the number of sheep that ate pellets before loading on the ship. Half of the deaths aboard ship occurred in 25% of 133 lines of sheep in the 5 cohorts. In each cohort the median per cent death rate (and range) per line was 1.3 (0.3 to 11.9), 1.1 (0.0 to 5.7), 1.8 (0.0 to 6.8), 2.3 (0.0 to 14.3) and 0.9 (0.1 to 5.4).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Evidence for freedom from Johne's disease in cattle and goats in Western Australia   总被引：1，自引：0，他引：1  

TM ELLIS  RT NORRIS  PAJ MARTIN  RH CASEY  CD HAWKINS 《Australian veterinary journal》1998,76(9):630-633

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Integrated optoelectronic devices based on conjugated polymers   总被引：1，自引：0，他引：1  

H Sirringhaus  N Tessler  RH Friend 《Science (New York, N.Y.)》1998,280(5370):1741-1744

An all-polymer semiconductor integrated device is demonstrated with a high-mobility conjugated polymer field-effect transistor (FET) driving a polymer light-emitting diode (LED) of similar size. The FET uses regioregular poly(hexylthiophene). Its performance approaches that of inorganic amorphous silicon FETs, with field-effect mobilities of 0.05 to 0.1 square centimeters per volt second and ON-OFF current ratios of >10(6). The high mobility is attributed to the formation of extended polaron states as a result of local self-organization, in contrast to the variable-range hopping of self-localized polarons found in more disordered polymers. The FET-LED device represents a step toward all-polymer optoelectronic integrated circuits such as active-matrix polymer LED displays.  相似文献   

Carbon structures with three-dimensional periodicity at optical wavelengths   总被引：1，自引：0，他引：1  

AA Zakhidov  RH Baughman  Z Iqbal  C Cui  I Khayrullin  SO Dantas  J Marti  VG Ralchenko 《Science (New York, N.Y.)》1998,282(5390):897-901

Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials.  相似文献   

Cooperating veterinarians and animal physical therapists: a win-win situation     

van Houten D  Blom G  Haveman S  Michielsen I 《Tijdschrift voor diergeneeskunde》2011,136(2):116-117

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