Sorption and thermodynamic properties of buried juvenile <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. wood aged 1,170 ± 40 BP

The hygroscopicity and thermodynamic properties of buried juvenile Pinus sylvestris L. wood with an age of 1,170 ± 40 BP were compared with the corresponding values of juvenile wood of the same species from recently cut trees. The 35 and 50°C isotherms were plotted following the saturated salts method and subsequently fitted in accordance with the GAB model. The isotherms were then compared by means of the hysteresis coefficients. X-ray diffractograms were used to analyse the crystal structure of the cellulose. The effect of time on the buried wood caused hemicelluloses degradation and a decrease in the crystallinity index and the crystallite length, resulting in an increase in the proportion of amorphous zones. Because of this, the equilibrium moisture contents of the buried wood are higher than of the recent wood, both in adsorption and desorption. In terms of the thermodynamic properties, the heat involved is greater in the buried wood than in the recent wood.     

Perceptions of silvopasture systems among adopters in northeast Argentina

Farmers’ perceptions over time of an agroforestry technology can have an important impact on adoption and disadoption. Their perceptions, in turn, may be influenced by the type and scale of farm they own and the social networks they create. We examined the factors underlying producers’ perceptions of silvopasture systems at the time of adoption and perceptions following several years of experience, and the factors explaining discontinuance of systems in Argentina. We found that while most adopters indicated that other people influenced their decision about whether or not to adopt silvopasture, the type of person that influenced them (professionals vs. other farmers) did not affect adopters’ perceptions of the relative benefits and challenges of the system. However, farm scale and farm type did explain farmers’ perceptions to a good degree. Smaller-scale farmers were less likely to see costs and returns as benefits of the system, but more likely to see cash flow properties as important advantages. Farmers’ perceptions after experiencing the system were good predictors of likely discontinuance, but influential people, farm scales, farm type, and perceptions at the time of adoption were not.     

Economies of scale for juvenile production of common snook (Centropomus undecimalis Bloch)

Abstract

Construction and operating costs for three common snook (Centropomus undecimalis) hatcheries in Florida, USA, are illustrated. Hypothetical capacities and targets of the three hatcheries (Scenarios I, II and III respectively) were 615, 000 juveniles (8 ‐ 10 g in weight) for stock enhancement, and 1, 275, 000 and 3, 000, 000 juveniles (1‐g in weight) for commercial grow‐out. Estimated production costs were lower than for many marine finfish species. The 20‐year mean costs per 1, 000 juveniles were estimated to be $324, $215, and $159, for hatcheries I, II, and III respectively, and the initial capital investments were $731, 660, $1, 162, 460, and $1, 896, 030¹, respectively. Major cost items of annual production were labor (22 ‐ 33%), supplies (14 ‐ 20%), fixed costs (15 ‐ 17%), and interest (13 ‐ 15%). The most profitable hatchery was the 3 million 1‐g juvenile hatchery due to the hatchery size effect, with a net present value (NPV) of $1, 760, 000, an internal rate of return (ERR) of 81%, a payback period of 3.6 years, and a profitability index of $2.86 for every dollar invested. Possible cost reductions to increase financial profitability were discussed.     

Comparative chemistry and insect antifeedant action of traditional (Clevenger and Soxhlet) and supercritical extracts (CO2) of two cultivated wormwood (Artemisia absinthium L.) populations

A comparison between traditional extraction techniques (hydrodistillation and organic solvent extraction) and supercritical fluid extraction was made for two different populations and crops of Artemisia absinthium L., cultivated in the field and aeroponically. The composition of the extracts, volatile and non volatile oils, was analyzed by GC-MS and HPLC-DAD, respectively. The antifeedant and phytotoxic activity of the extracts was tested on insect pests (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi) and plants (Lactuca sativa and Lolium perenne). The supercritical extracts exhibited stronger antifeedant effects than the traditional ones (up to 8 times more active) with moderate selective phytotoxic effects on L. perenne root growth (<50% inhibition).     

The Reuse of Water on the Culture of Pacific White Shrimp,Litopenaeus vannamei,in BFT System

The use of the same water over multiple culture cycles in a biofloc technology system can be highly beneficial. This study evaluated the effect of different levels of biofloc‐rich water on selected water quality indicators and on the productive performance of Pacific white shrimp, Litopenaeus vannamei, juveniles (3.5 g) stocked at 312 juveniles/m³ and cultured under conditions of no water exchange. The study was performed over a 30‐d period in an 800‐L tank system. A total of four biofloc enrichment levels (25, 50, 75, and 100%) and control (0%) were tested with three replicates each. Significant differences in nitrogen compounds were found between the biofloc‐enriched water and the zero‐enrichment treatment. No statistically significant differences among the biofloc‐enriched treatments were found in survival, final weight (8.25 g), and feed conversion ratio (FCR) (1.08). The shrimp raised in clear seawater (i.e., a 0% biofloc enrichment) were significantly smaller (7.37 g vs. 8.25 g) and showed a higher FCR (1.52 vs. 1.08) than the shrimp cultured in the biofloc‐rich water. Nevertheless, no differences in yields were found between treatments. The results of this study suggest that culture in biofloc‐enriched water produces higher levels of water quality and shrimp performance than culture in natural seawater.     

Monitoring of eucalyptus sprouts control using digital images obtained by unmanned aerial vehicle

This study evaluated the effectiveness of chemical control for eradicating eucalyptus sprouts using images obtained with Unmanned Aerial Vehicle (UAV). The study was carried out in eucalyptus plantations in Itabela, BA, in replanting areas during pre-planting application of herbicide. Aerial images obtained by a UAV were used to evaluate the effectiveness of the herbicide application for sprouts control. After the images were acquired, they were processed to calculate the normalized difference vegetation index (NDVI) and submitted to a supervised classification to quantify the percentage reduction of sprout green matter. The percentage data were submitted to analysis of variance and the means were compared by Tukey test at 5%. The differences, both visual and average percentages were observed only during the evaluation period with no evident effect of the treatments on sprout control. The images provided by the UAV allowed to monitor and identify visually the plots where biomass reduced or increased and to evaluate the effectiveness of chemical control of eucalyptus sprouts, indicating areas where it was nonexistent, partial or total.     

Peroxicoagulation and Solar Peroxicoagulation for Landfill Leachate Treatment Using a Cu–Fe System

Leachates, particularly those from mature landfills, are difficult to treat by biological processes because of their high toxicity and low biodegradability. Therefore, the development of new treatment technology is necessary. The treatment of landfill leachate by peroxicoagulation and solar peroxicoagulation using a batch electrolytic reactor with a Fe cathode and a Cu anode is proposed. The tested operational variables included pH (2.8 and 8.2), current density (11 and 16 mA cm^?2), treatment time (5, 10, 15, 20, 25, and 30 min), and presence of solar ultraviolet (UV) light and were collected using a compound parabolic collector. The optimum conditions were a pH, current density, and treatment time of 2.8, 16 mA cm^?2, and 10 min, respectively. The presence of UV did not have a significant effect. The chemical oxygen demand and biochemical oxygen demand removed were 62.3% and 55.5%, respectively. The results of UV-visible absorption, fluorescence, and Fourier transform infrared spectroscopy measurements confirm the oxidation process.     

Recovery from rocuronium-induced neuromuscular block was longer in the larynx than in the pelvic limb of anesthetized dogs

Objective

To determine if neuromuscular monitoring at the pelvic limb accurately reflects neuromuscular function in the larynx after administration of rocuronium in anesthetized dogs.