Groundwater Purification in a Polymetallic Mining Area (SW Sinai,Egypt) Using Functionalized Magnetic Chitosan Particles

A magnetic glycine-grafted chitosan sorbent (Gly) was functionalized to produce a hydrazide derivative (HGly). The two sorbents were tested in batch mode for the sorption of a series of 10 metal ions present in the groundwater collected in three wells in the Wadi (valley) Nasib mining area (SW Sinai, Egypt). HGly is much more efficient for metal recovery than Gly. Under selected experimental conditions (sorbent dosage 1.5 g L^?1), the sorption efficiency is not sufficient for achieving the standard levels for drinking water: the most problematic metal ions in terms of drinkability remain aluminum (too high metal concentration in the groundwater), cadmium, and chromium for the three wells (and nickel in the case of only one well). Increasing the sorbent dosage improves the treatment efficiency. The sorbent (HGly) was tested in fixed-bed columns. The breakthrough curves were compared for the different metals for the groundwater collected in the most contaminated of the three wells. The levels of metal concentration in the treated groundwater are too high for direct use in irrigation. However, they are consistent with the standards for livestock drinking water (based on FAO recommendations, Food and Agriculture Organization of the United Nations). The metals can be readily desorbed using 0.5 M HCl solutions with a relatively high concentrating effect (i.e., 50 times). The re-use of the sorbent for three successive cycles of sorption/desorption cycles shows a progressive but weak decrease in sorption and desorption performances.     

Effect of Nitrogen Application Timing on Yield Components,Fodder, Grain,and Oil Yields of Brassica Cultivars

The dual-purpose use of Brassica cultivars means cutting or grazing the crop as fodder and then letting it to re-grow and produce grain with little or no yield penalty. A field experiment was conducted in randomized complete block design with split plot arrangement with three replications. Three Brassica cultivars, three nitrogen application timing, and cutting treatments were included in the experiment. The findings indicated that Brassica cultivar Abasin-95 produced higher fresh and dry fodder yields, seeds pod^?1, seed, biological, and oil yields. However, NIFA Raya resulted in a higher number of pods and branches plant^?1. Likewise, fresh and dry fodder yields were higher with nitrogen (N) application all at sowing. Nitrogen applied in two splits resulted in a higher number of pods plant^?1 and grain yield. Cutting suppressed all parameters except 1000 grain weight. Uncut plots produced significantly higher branches plant^?1, pods plant^?1, seeds pod^?1, seed, biological, and oil yields than cut plots.     

Evaluation of cognitive loads imposed by traditional paper-based and innovative computer-based instructional strategies

Strategies of presenting instructional information affect the type of cognitive load imposed on the learner's working memory. Effective instruction reduces extraneous (ineffective) cognitive load and promotes germane (effective) cognitive load. Eighty first-year students from two veterinary schools completed a two-section questionnaire that evaluated their perspectives on the educational value of a computer-based instructional program. They compared the difference between cognitive loads imposed by paper-based and computer-based instructional strategies used to teach the anatomy of the canine skeleton. Section I included 17 closed-ended items, rated on a five-point Likert scale, that assessed the use of graphics, content, and the learning process. Section II included a nine-point mental effort rating scale to measure the level of difficulty of instruction; students were asked to indicate the amount of mental effort invested in the learning task using both paper-based and computer-based presentation formats. The closed-ended data were expressed as means and standard deviations. A paired t test with an alpha level of 0.05 was used to determine the overall mean difference between the two presentation formats. Students positively evaluated their experience with the computer-based instructional program with a mean score of 4.69 (SD=0.53) for use of graphics, 4.70 (SD=0.56) for instructional content, and 4.45 (SD=0.67) for the learning process. The mean difference of mental effort (1.50) between the two presentation formats was significant, t=8.26, p≤.0001, df=76, for two-tailed distribution. Consistent with cognitive load theory, innovative computer-based instructional strategies decrease extraneous cognitive load compared with traditional paper-based instructional strategies.     

Survey of ixodid ticks in domestic ruminants in Bedelle district,Southwestern Ethiopia

A survey aimed at determining the status of ticks in cattle, sheep and goats in Bedelle district (Southwestern Ethiopia) was carried out from November 2007 to April 2008. Out of the total 330 animals examined, 314 (95.2%) were found to be infested (harbouring of at least a single tick). High rates of infestations were recorded across all three host species. Factors like month of collection, age and sex of host species did not show significant association with infestation rates. A total of 5,507 ticks belonging to three genera (i.e. Amblyomma, Boophilus and Rhipicephalus) were collected during the study period of which six species were identified. The species of ticks encountered comprise of Amblyomma cohaerens (44.1%), Amblyomma variegatum (13.8%), Amblyomma lepidum (1.2%), Boophilus decoloratus (24.9%), Rhipicephalus evertsi evertsi (14.3%) and Rhipicephalus lunulatus (1.7%). As about 86.7% (4,772) of the ticks were collected from cattle, it was recognised that this could be an evidence of host preference where cattle are serving as principal host while sheep and goats serve as alternative hosts. The role of ecological factors and little attention paid by livestock owners for treatment of animals against ticks are suggested to result in the abundance of ticks. Acaricide spraying should be strategically applied to control ticks. Better result could be achieved if an emphasis is being put on spraying cattle. Studies on tick-borne diseases, involvement of wildlife species as well as related factors are recommended as they may provide a valuable basis for designing and launching an all-round control programme in the country.     

Defoliation and nitrogen effects on photosynthesis and growth of Eucalyptus globulus

Plant responses to defoliation are complex. We established a field experiment in a nine-month-old Eucalyptus globulus Labill. plantation to examine the effects of pattern (upper crown versus lower crown removal), frequency (single, double or triple defoliation within a 12-month period) and severity (25 versus 38% of leaf area removed) of defoliation and the effect of soil nitrogen (N) on photosynthetic processes and stem growth. The photosynthetic responses observed following defoliation could be attributed to changes in source:sink ratios. Light-saturated CO(2) uptake (A(max)) increased with increasing severity and frequency of defoliation irrespective of defoliation pattern. Seedlings defoliated in autumn did not exhibit increases in A(max) until the following spring, whereas there was no such delay in photosynthetic responses associated with spring defoliation. Application of N before defoliation allowed trees to compensate for the effect of defoliation on stem diameter growth, which could not be explained simply in terms of increases in A(max). The observed increases in stem diameter increment following N fertilization of defoliated trees suggested increases in leaf area development, and there were changes in the leaf area:leaf dry mass ratio that may have increased light absorption by the crown. Nitrogen fertilization also increased partitioning of dry mass to branches at the expense of main stems, suggesting that N supply was important in rebuilding crowns following a defoliation event.     

Molecular and Biological Characterization of Lettuce mosaic virus (LMV) Isolates Reveals a Distinct and Widespread Type of Resistance-Breaking Isolate: LMV-Most

ABSTRACT Lettuce mosaic virus (LMV) causes an economically important seedborne and aphid-transmitted disease of lettuce and ornamental crops worldwide. The genetic diversity among 73 LMV isolates was examined based on a 216-nucleotide sequence at the variable region encoding the NIb-coat protein junction. Three clusters of LMV isolates were distinguished: LMV-Yar, LMV-Greek, and LMV-RoW. In the latter cluster, two subgroups of isolates, LMV-Common and LMV-Most, accounted for a large proportion of the LMV isolates analyzed. These two subgroups included the seedborne isolates, consistent with this property contributing a selective advantage and resulting in widespread distribution. In addition to being seedborne, LMV-Most isolates overcome the two resistance genes commonly used in lettuce, mo1(1) and mo1(2), and thus represent a potential threat to lettuce cultivation. The complete sequence of an LMV-Most isolate (LMV-AF199) was determined, allowing a better definition of the genetic relationships among LMV-Most, LMV-Common, and an additional isolate of the LMV-RoW cluster.     

测定采食量是精确配合日粮所必需的

养禽者和营养师需要关于采食量的准确数据才能经济而精确地进行日粮配合。采食量的实际测定，对于当今的现代鸡舍来说是一项艰难的任务。本文是作者发表在美国中西部家禽联合会2002大会营养学专题讨论会上的。     

Transfer of immunoglobulins and survival of newborn calves

The survival of 405 newborn calves in a large Central Florida dairy was monitored for a period of 20 weeks. Post-colostral serum samples were obtained from 234 newborn calves 2 to 7 days postpartum and assayed for total serum protein concentration using a refractometer. In the dams, the concentration of colostral immunoglobulins (Ig) at the first postpartum milking was determined by a colostrometer. Season of calving, sex, and breed of the newborn calves were recorded. The likelihood a calf would have satisfactory serum protein (greater than or equal to 5.5 g/dl) given its breed, season of calving, dam's colostral Ig, and dam's calving body condition score were determined using logistic regression analysis. Factors affecting the survival of these calves, up to 20 weeks of age, were studied using the Cox's proportional hazard model. Newborn calves' serum proteins ranged from 3.0 to 8.3 g/dl with a mean of 5.1 g/dl. Calves born to dams with satisfactory colostral Ig (greater than or equal to 50 mg/ml) were unlikely to have satisfactory serum proteins (odds ratio = 0.4) after adjustment for season of calving, parity, breed and dam's body condition score. Calves born from October to January were 3 times more likely to have satisfactory serum proteins compared to calves born during the period of February to July. However, there was no difference in serum proteins between calves born in August and September compared to the ones born in February to July. The survival rate of calves born to dams with satisfactory levels of colostral Ig was poor compared to ones born to dams with low colostral Ig.     

Effects of a Chenopodium-based botanical insecticide/acaricide on Orius insidiosus (Hemiptera: Anthocoridae) and Aphidius colemani (Hymenoptera: Braconidae)

UDA-245 is a Chenopodium-based natural insecticide. Forty-eight hours after treatment with this compound, Orius insidiosus (Say) and Aphidius colemani Viereck showed slight contact toxicity at 5 g AI liter(-1). There was no residual toxicity to A colemani. These two beneficials are currently used in commercial flower and vegetable greenhouses for the management of thrips, spider mites, aphids and small caterpillars. In contrast, abamectin and insecticidal soap were toxic by contact to both species. UDA-245 did not reduce the number of eggs laid by treated O insidiosus. The eclosion of these eggs was also not adversely affected by UDA-245. The other two insecticides, abamectin and insecticidal soap had no effect on the emergence of A colemani from treated aphid mummies. However, abamectin decreased the percentage of aphid parasitism by A colemani following a residual treatment. The LC50 for UDA-245 for the two beneficials is slightly over twice the recommended field dose.