无机电解质对十二烷基硫酸钠性质影响的研究

选择不同类型的无机电解质(NaCl、Na2SO4、Na3PO4、MgCl2、AlCl3),考察了电解质对十二烷基硫酸钠(SDS)表面张力、临界胶束浓度、润湿力、发泡力、乳化力的影响规律。实验表明,无机电解质对SDS的CMC影响显著,随着无机盐的加入,CMC降低,表面活性增强。当加入的氯化钠浓度达到0.3mol/L时,SDS的CMC降到了原来的十分之一,高价位离子对CMC影响大于低价位离子,同价位不同离子影响差别不大;SDS润湿性、乳化性、泡沫性能较好,加入电解质后,其润湿性增强,乳化性、泡沫高度和稳泡性降低。     

The effect of dietary poultry litter supplementation on beef chemical, cooking, and palatability properties and consumer acceptance

Twenty Holstein steers were randomly and equally allocated to two groups (treatment and control) at a mean weight of 334.3 kg and were backgrounded for 133 days and fed a finishing diet for 99 days under commercial conditions. Control animals received 97.1% corn silage, 2.6% canola meal, and 0.3% mineral mix during backgrounding and 72.6% corn silage, 3.9% canola meat, 23% barley and 0.2% mineral mix during finishing. Treated animals received 95.3% corn silage, 4.4% poultry litter, and 0.3% mineral mix during backgrounding and 62.1% corn silage, 5.6% poultry litter, 22% barley, and 0.2% mineral mix during finishing. The poultry litter was provided as a pelleted. At the end of the finishing period, all animals were harvested. After 144 h at 2 °C, the boneless longissimus thoracis et lumborum muscles were removed, cut into steaks (1.9 cm thick) and roasts, vacuum packaged, and frozen. A steak adjacent to the 13th thoracis vertebra of alternate carcass sides was displayed under simulated retail conditions for 4 days and then analyzed for moisture and fat content. A steak immediately posterior to the 13th thoracis vertebra of alternate carcass sides was evaluated by an experienced trained six-member laboratory panel for palatability attributes. The steak immediately posterior to the steak used for sensory evaluation was used for shear force evaluation. A roast constituting the reminder of the longissimus lumborum muscle was used to obtain complete flavour and texture profiles. Total cooking losses were determined and cooking times were recorded for both steaks and roasts. All remaining steaks (1180) were distributed at random to households to determine consumer acceptance. Treated samples were essentially indistinguishable from control samples in both palatability and consumer acceptance, indicating poultry litter supplements can be utilized in feedlot rations for cattle without compromising either palatability or consumer acceptance.     

Microdistribution patterns of macroinvertebrate communities upstream and downstream of organic effluents

The present study analyses the distribution patterns of macroinvertebrate communities in four microhabitats (riffles, glides, leaf litter and bank roots) upstream and downstream of two waste water treatment plant (WWTP) effluents in northern Spain rivers. Macroinvertebrate communities were analysed in November 2006 by taking 5 samples from each of the microhabitats under unaffected (upstream WWTP) and affected (downstream WWTP) conditions, respectively. Water velocity, depth, substrate coarseness and hydraulic stress by means of the Froude number were also estimated at all sampling locations.Under unaffected conditions, the abundance and presence/absence of certain macroinvertebrate taxa were mainly determined by hydraulic characteristics (water velocity and Froude number) and feeding resource availability. However, neither macroinvertebrate richness nor abundance were neither significantly correlated with hydraulic stress nor substrate coarseness, although the number of macroinvertebrate taxa increased in microhabitats with high structural complexity. Macroinvertebrate abundance increased downstream of both WWTPs, while macroinvertebrate richness was not adversely affected by the organic enrichment of water. The structure and composition of macroinvertebrate communities occurring in riffles was similar under unaffected and affected conditions, while communities from leaf litter and submerged bank roots showed important changes above and below the WWTPs, indicating that they are probably the most appropriate communities for water quality assessment.     

水曲柳林下凋落物热解特性及动力学分析

利用热重分析法对水曲柳林下凋落物的热解行为进行研究,分析不同的试验气氛、升温速率及粒径对热解过程的影响,采用Coast-Redfern 法进行动力学分析。结果表明：林下凋落物热解分为失水、轻微失重、主要失重和炭化4 个阶段,试样的稳定性大小依次为：水曲柳树枝>水曲柳树皮>水曲柳树叶>福王草;试样在氮气气氛下有1 个失重峰,在空气气氛下有2 个失重峰,在空气气氛下失重率较大,热解更充分;随着升温速率增加,热失重曲线向高温侧移动,失重速率增加,且存在滞后效应;粒径大小对试验影响较小,60 目粒径试样失重率最大;4 种试样活化能由大到小分别为水曲柳树枝、水曲柳树皮、水曲柳树叶和福王草。     

Social environment and reproduction in female European rabbits (Oryctolagus cuniculus): Benefits of the presence of litter sisters.

The authors investigated in an observational study the consequences of the presence of litter sisters on the social interactions and on reproductive performance of young female European rabbits (Oryctolagus cuniculus) from a population living under seminatural conditions. In early winter, when all young females were settled in a social group, they were characterized by the presence or absence of litter sisters in their groups. Females with litter sisters in their groups displayed significantly more positive social interaction with females of their social group compared to females without sisters, whereas this difference was mainly due to the high frequency of positive social interactions among the respective sisters. Such differences between the females of both categories were already apparent during the animals' juvenile phase, before the females integrated into a particular group: females which later had litter sisters in their group showed more positive social behavior than females which later no longer had litter sisters. During their first breeding season, females with litter sisters present generally started to breed earlier by an average of 14 days. A more favorable social environment might have possibly facilitated the earlier onset of breeding in females with present litter sisters by attenuating the negative consequences of stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relative proportion of inorganic and total nitrogen in broiler litter as determined by various methods

We report relative proportion of inorganic N in broiler litter and compare the regular Kjeldahl method with three of its modifications (the salicylic acid–thiosulfate modification, the Devarda's alloy modification, and the potassium permanganate–reduced iron modification), and with a Leco‐combustion (CHN‐600) method for the degree to which they include NO₃^?‐N and NO₂^?‐N in broiler litter analysis. Inorganic N in the litter (<500 µm) was determined after extraction with 2 mol L^?1 KCl. NH₄⁺‐N and (NO₃^? + NO₂^?)‐N in the filtrate were analysed by steam distillation while NO₂^?‐N was determined by a modified Griess–Ilosvay colorimetric method. For the determination of total N, 25 mg broiler litter (<1000 µm) was digested according to four semi‐micro‐Kjeldahl methods in a 100‐mL Pyrex Kjeldahl flask using an electrically heated six‐flask micro‐Kjeldahl digestion rack. Ammonium‐N in the digest was determined by steam distillation. The results showed that inorganic N represents a small portion of total N in the samples. Ammonium is the most dominant inorganic N (1.61–5.39 g kg^?1) in the samples; it represents between 42 and 94% of the inorganic N. The (NO₃^? + NO₂^?)‐N contents varied between 0.19 and 5.56 g kg^?1 while NO₂^?‐N contents in the samples were negligible (<0.6 g kg^?1). The regular Kjeldahl method and its modifications recovered all the NH₄⁺‐N added but recovery of added NO₂^?‐N and NO₃^?‐N varied considerably with the methods. The Devarda's alloy and the potassium permanganate methods showed the highest N measurements while the Leco‐combustion showed the lowest N measurements. Copyright © 2006 Society of Chemical Industry     

Accumulation, transfers and dissipation of energy in chir pine forests

Energy stored and net energy fixed at four sites of natural chir pine forest were assessed. Of the total energy stored by the vegetation (3836.6 GJ ha⁻¹) 98.7% was in trees, 0.4% in shrubs and 0.9% in the herb layer. Net energy fixed by the vegetation was 318.5 GJ ha⁻¹ yr⁻¹ of which the shares of tree, shrub and herb layers were 84.7% 0.9% and 14.4%, respectively. The energy capture efficiency (photosynthetic radiation) of the vegetation was 1.07% (0.91% in trees, 0.01% in shrubs and 0.15% in herbs). Of the total transfer of energy to the forest floor through litter fall (142.7 GJ ha⁻¹ yr⁻¹ leaf litter and woody litter accounted for 68.4% and 31.6%, respectively. Energy stored in the above-ground biomass of the trees from 2877 ha or in the net annual above-ground production from 39,903 ha is sufficient to operate a 50 MW generating station for one year. Total biomass and net production from 1 ha of natural chir pine forest is sufficient to meet the energy need of an average household of western Himalaya for 61.1 and 4.4 years, respectively.     

The Plant Growth Inhibitor Nagilactone Does Not Work Directly in a Stabilized Podocarpus nagi Forest

Nagilactones isolated from Podocarpus nagi are known for poisonous physiological activities to organisms. To clarify the allelopathic potential of nagilactone to wild plants, the seasonal changes in nagilactone contents in throughfall, leaf litter, and soil were monitored monthly in a podocarp forest at Mt. Mikasa, Nara City, central Japan. The average annual nagilactone concentrations in throughfall, leaf litter, and surface soil at 0–10 cm depth were 4.7 × 10^–12 g/ml, 3.8 × 10^–4 g/g and 3.1 × 10^–7 g/g, respectively. The nagilactone flux from canopy leaves to the forest floor via throughfall was 5.2 × 10^–2 g/ha/yr, which was far smaller than that via leaf litterfall: 765.3 g/ha/year. The disappearance of nagilactones from leaf litter and the nagilactone accumulation in the Ao layer and mineral soil were also studied. Nagilactone in leaf litter rapidly disappeared and its relative disappearance rate was 5.8/yr. Nagilactone concentration in mineral soil also decreased rapidly with an increase in soil depth and could not be detected in soil at 40–100 cm depth. The total mass of nagilactones was 177.3 g/ha in the Ao layer and 105.0 g/ha in mineral soil. These quantities in nagilactone dynamics give a very rapid turnover time of 0.37 year (4.4 months) in a soil nagilactone pool, implying the possibility of the reabsorption of nagilactone by P. nagi, while the allelopathic effects of nagilactone to other plants in the podocarp forest are questionable.     

Adsorption of trace elements from poultry litter by montmorillonite clay

Poultry litter (PL) is used as fertilizer on agricultural lands because of its high nutrient content. However, the litter also contains trace elements such as As, Cd, Cu, Pb, and Zn. On land application of PL, these trace elements may be absorbed by crops, leach into groundwater, or enter the aquatic system as run-off. The objective of this research was to study the effect of the addition of montmorillonite clay-mineral (CM) in reducing the release of trace elements from PL. Cd, Cu, and Zn showed significant decreases of 29, 34, and 22%, respectively, in PL aqueous leachate (compared with the control-PL without CM) on mixing with 0.05 g CM but no change in As, Co, and Cr concentrations was observed. Lead showed a significant increase in PL aqueous leachate on mixing with 0.2 g CM but Pb concentration was two orders of magnitude less than in CM aqueous leachate alone. On washing, the settled precipitate (PL+CM) in the centrifuge tubes with water (desorption study) most of the adsorbed metals (Cd 85%, Cu 61%, and Zn 100%) were released. The results of this study show that the addition of CM resulted in significant adsorption of Cd and Cu from PL.     

Taste sensitivity of detritivorous mosquito larvae to decomposed leaf litter

Dietary leaf litter chemistry is known to play an important ecotoxicological role in the plant–mosquito interaction in subalpine flooded areas surrounded by vegetation because of differential larvicidal effects of insoluble polyphenols formed during the leaf decaying process. This dietary interaction was investigated through comparative evaluation of the role of toxic/nontoxic leaf litter in both larval foraging and feeding behavior, by using different samples of decomposed alder leaf litter and larval Aedes aegypti as experimental references. Track analysis showed significant differences in larval foraging behavior in the absence or presence of leaf litter. Comparative alimentary preference investigations and further track analysis suggested that larvae are unable to detect leaf litter toxicity. These characteristics of the larval behavioral feeding pattern suggested that: (1) decomposed leaf litter may be involved as an important attractive food source in the habitat selection and evolutionary history of culicids, and (2) preingestive behavioral mechanisms appear to be minimally involved in the differential larval dietary adaptation to toxic leaf litter. These results may have interesting consequences for culicid biological control.