Synthesis of polycrystalline chalcopyrite semiconductors by microwave irradiation

Polycrystalline samples of the chalcopyrites CulnS(2), CulnSe(2), and CulnSSe were Prepared from stoichiometric mixtures of the pure elements by microwave irradiation. The reactions were performed in sealed quartz tubes in as few as 3 minutes. The products were analyzed by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and x-ray photoelectron spectroscopy. The surface morphology and shape of the particles produced by this method suggest that the products are formed from liquid melts. This method could be applied to the production of bulk chalcopyrite as sources for thin film growth.     

When less is more: heterogeneity in grass patch height supports herbivores in counter-intuitive ways

Herbivores are an integral part of the African landscape and have evolved with the vegetation to create the savanna landscape. Managers of these landscapes can benefit from a better understanding of how indigenous herbivores use the landscape to which they are adapted. In this study we observed which patches were frequently utilised, by doing regular monthly road counts, grass height observations and dung counts on selected short grass patches in the Kruger National Park. Smaller-framed impala and blue wildebeest (meso-herbivores) were most regularly seen on these nutritious patches, while from dung deposits it was clear that the even larger-framed buffalo (mega-herbivores) spent time there. This preference can be explained by considering the nutritional needs and food intake of the herbivores. Smaller-framed herbivores seem to be able to satisfy their dietary requirements on the high-quality forage patches, while larger-framed herbivores seem to supplement the quality forage by also spending foraging time on areas of higher grass biomass. From this insight we propose that range management should take herbivore preferences into account and allow herbivores to select and concentrate their foraging on the most nutritious forage. This approach is likely to decrease inputs while allowing animals to maintain or increase production.     

Bone Morphogenetic Protein‐6 (BMP‐6) Stimulates the Antrum Formation by the Regulation of its Signalling Pathway in Caprine Pre‐antral Follicles Cultured In Vitro

BMP‐6 has been found to be important to ovarian cells and oocyte, as well as to uterus. Thus, this study investigated the effect of bone morphogenetic protein (BMP‐6) and recombinant follicle‐stimulating hormone (rFSH) alone or in combination on the in vitro culture (IVC) of isolated caprine secondary follicles (Experiment 1) and the mRNA levels for BMP receptors/Smad signalling pathway (BMPR1A, BMPR2, SMAD1, SMAD4, SMAD5, SMAD6, SMAD7 and SMAD8) in vivo and in vitro using BMP‐6 (Experiment 2). Secondary follicles were cultured in αMEM⁺ alone (control medium) or supplemented with BMP‐6 at 1 or 10 ng/ml and rFSH alone or the combination of both BMP‐6 concentrations and rFSH. The results from Experiment 1 showed that the antrum formation rate was higher in the BMP‐6 at 1 ng/ml (p < 0.05) than in MEM. In Experiment 2, the mRNA expression for BMPR2, SMAD1, SMAD5 and SMAD6 was detected in non‐cultured control and after in vitro culture (MEM and 1 ng/ml BMP‐6); while the expression of SMAD7 and SMAD8 mRNA was only detected after IVC, SMAD4 was only detected in the BMP‐6 at 1 ng/ml treatment. In conclusion, the low BMP‐6 concentration positively influenced antrum formation and ensured normal mRNA expression for BMP receptor and Smads after IVC of caprine secondary follicles.     

Epigallocatechin‐3‐gallate (EGCG) and green tea polyphenols do not improve stallion semen parameters during cooling at 4°C

Stallion semen storage for artificial insemination is mainly based on liquid cooled storage. In many stallions this technique maintains sperm quality for an extended period of time (24–72 hr) at 7°C. While this technique is commonly used in the horse industry, there can be a decline in fertility in some stallions, due to an inability of their sperm to tolerate the cool storage process. The aim of the present work was to evaluate the effect of two natural antioxidants (epigallocatechin‐3‐gallate (EGCG) at 20, 60 and 120 μm and green tea polyphenols, and p at .001, .01 and .1 mg/ml) on some sperm parameters (sperm motility, viability/acrosome integrity and DNA quality) in extended semen immediately after its collection (T0) and after 2, 6, 24 and 48 hr of cool storage. Two ejaculates from three trotter stallions were analysed after 48 hr of storage at 4°C. No beneficial effect on the analysed parameters was observed: the two antioxidants were not able to improve sperm quality after 48 hr of storage. These results are in agreement with previous findings on the effect of different antioxidants reported by other researches, who have demonstrated that stallion semen keeps good antioxidant capacity after dilution for 24 hr. In conclusion, the positive effect exerted by antioxidant molecules in other species is not confirmed in the equine one.     

Stress response of Crassostrea virginica (Gmelin, 1791) oysters following a reciprocal transfer between upriver and downriver sites

This study was designed to assess the physiological impact of transferring oysters between upriver and downriver aquaculture sites, a common practice in North America that is primarily aimed at reducing disease infections and predation on cultured stocks. In May 2009, oysters (Crassostrea virginica) were reciprocally transferred between an upriver and a downriver site in the Richibucto estuary in eastern Canada. Mortality, tissue and cellular stress responses were subsequently evaluated in August and October 2009. Overall, oyster mortality remained low (~5%) throughout the 5‐month study period with no significant difference between sites or oyster sources. However, by October oysters reared at the upriver site, regardless of their origin, had significantly higher levels of lysosomal membrane destabilization (63.6%, SE = 1.9) and digestive tubule atrophy (33.3–42.4%, SE = 3.6) than oysters reared at the downriver site (47.5%, SE = 1.8; 15.6–19.1%, SE = 3.8 respectively). They also exhibited a greater salinity differential between their mantle/haemolymph fluids and the ambient seawater, possibly indicating more restricted exchange with the environment. In general, the transfer of upriver oysters to a downriver site had a positive impact, i.e. lower levels of lysosomal destabilization and tubule atrophy, whereas transfer of downriver oysters upriver had the opposite effect. These results suggest that upriver environmental conditions negatively impact cellular and tissue integrity in oysters without leading to mortality during the summer–autumn period.     

Development of an Image Processing System and a Fuzzy Algorithm for Site-Specific Herbicide Applications

In precision farming, image analysis techniques can aid farmers in the site-specific application of herbicides, and thus lower the risk of soil and water pollution by reducing the amount of chemicals applied. Using weed maps built with image analysis techniques, farmers can learn about the weed distribution within the crop. In this study, a digital camera was used to take a series of grid-based images covering the soil between rows of corn in a field in southwestern Quebec in May of 1999. Weed coverage was determined from each image using a greenness method in which the red, green, and blue intensities of each pixel were compared. Weed coverage and weed patchiness were estimated based on the percent of greenness area in the images. This information was used to create a weed map. Using weed coverage and weed patchiness as inputs, a fuzzy logic model was developed for use in determining site-specific herbicide application rates. A herbicide application map was then created for further evaluation of herbicide application strategy. Simulations indicated that significant amounts of herbicide could be saved using this approach.     

Detection of a Babesia sp. genotype closely related to marsupial-associated Babesia spp. in male Haemaphysalis shimoga from Sarawak,Malaysian Borneo

In this study, Babesia screening was conducted in 55 rodents and 160 tick samples collected from primary forests and an oil palm plantation in Sarawak, Malaysian Borneo. PCR targeting the 18S ribosomal DNA revealed the presence of Babesia spp. DNA detected in two questing male Haemaphysalis shimoga ticks collected from the oil palm plantation. Sequence analysis revealed that both sequences were identical and had 98.6% identity to a Babesia macropus sequence obtained from Eastern grey kangaroos (Macropus giganteus) in Australia. Phylogenetic tree revealed clustering with marsupial-associated Babesia spp. in the Babesia sensu stricto clade. Whether or not H. shimoga is the competent vector and the importance of the Babesia sp. detected in this study warrants more investigation.     

Compressive properties of Hemp (Cannabis sativa L.) stalks

Compressive behaviour of hemp (Cannabis Sativ L.) stems is important for the design of hemp handling and processing machines. Experiments were carried out to measure the compressive properties of stems from two hemp varieties: Alyssa (grown for fibre only) and Petera (grown for both fibre and seed), produced in Manitoba, Canada. The physical properties of the hemp specimens were measured. For each variety, an air-dried hemp stem was divided into three height sections along the stem: upper, middle and lower. For each section, the hemp stem was further cut into 25.4 mm long specimens. Individual specimens were compressed in the axial and lateral directions using a universal testing machine. The load-displacement curves were recorded, and compressive properties were derived from the load-displacement curves. The outer diameter of the hollow hemp specimens varied from 6 to 17 mm; the linear density varied from 10 to 37 g m⁻¹. Diameter and linear density were greater for Petera than Alyssa, and at the lower height section than the higher section for both varieties. The compression tests showed that the maximum compressive load varied from 58 to 1425 N, and the energy requirement varied from 23 to 1809 mJ, depending on the variety, height section and diameter of stem, and compression direction. In general, the maximum compressive load and the energy requirement were greater in the lower section and for larger diameters; higher loads and energy were observed for Petera than for Alyssa and for the axial compression direction than for the lateral direction.     

Critical survey of interrelationships of nitrogen and amino acids in seeds

The present paper is intended for removing inconsistencies from available information concerning the interrelationhips of nitrogen (N) and amino acids in seeds (or grains). It consists of a critical survey of data reported in a series of papers by Mossé and collaborators (see Mossé and Huet, Sci. Aliments 1990, 10, 151 for review). These authors contended for perfectly linear relationships (A(i) = a(i)N + b(i)) to hold between N and amino acid i (g/100 g seed dry matter) for seeds of a given species on the basis of correlation coefficient (r) found to be close to 1. Three linear regressions are called upon to analyze variations in the amino acid compositions of 33 samples of pea seeds. The regression C(i) (g amino acid i/16gN) = 16a(i) + 16b(i)N(-)(1), not used customarily, is the more amenable to accommodate all the facts in pointing out values significantly lower than 1 for r(i)(2), and parameters a(i) and b(i) similar to those found with the regression A(i) = NC(i)/16 = a(i)N + b(i) whose r(i)(2) values, very close to 1, are overestimated on account of the presence of N in both sides of equation and sampling limited in number. Examination of variations in lysine content of maize grains as a function of N shows that the phenotypic variations for a given genotype are a poor fit to the linear relationship A(lys) = aN + b available in the literature, as determined from 153 commercial samples. It is concluded that linear N-amino acid relationships hold only approximately for predicting amino acid composition of seed of a given species from its N content.