Robust Ionic Liquid–Based Dispersive Liquid–Liquid Microextraction Method for Determination of Chromium(VI) in Saline Solutions

Robust ionic liquid–based dispersive liquid–liquid microextraction (IL-DLLME) is a fast and simple method for extraction and preconcentration of metal ions from samples with high salt content. This method can solve the problems associated with the limited application of the conventional IL-DLLME in these samples. In this procedure, the hydrophobic chelate of chromium with ammonium pyrrolidinedithiocarbamate (APDC) was extracted into the fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF₆]), which was dispersed into the aqueous sample solution. Several factors that influence the microextraction efficiency were investigated. In optimum conditions a linear calibration graph in the range of 0.5–70 μg L^?1 of Cr in the initial solution with r = 0.9998 was obtained. Detection limit was 0.16 μg L^?1 and relative standard deviation (RSD) for 20 μg L^?1 of Cr was 2.68% (n = 10), respectively. The proposed method was successfully applied for the determination of Cr(VI) in water samples and food additives.     

ED50 and ED95 of rocuronium during alfaxalone anesthesia in dogs

ObjectiveTo determine the median effective dose (ED₅₀) and effective dose required to depress the twitch value by 95% (ED₉₅) of rocuronium during alfaxalone anesthesia in dogs.Study designA randomized, prospective, crossover experimental study.AnimalsA total of eight adult Beagle dogs (four female, four male), weighing 10.3–14.6 kg and aged 6–8 years.MethodsThe dogs were anesthetized three times with 1.25-fold the individual minimum infusion rate of alfaxalone at intervals of ≥ 14 days. Neuromuscular function was monitored with train-of-four (TOF) stimulation of the peroneal nerve by acceleromyography. After recording the control TOF ratio (TOFRC) and first twitch of TOF (T1C), a single bolus dose of rocuronium 100, 175 or 250 μg kg^–1 (treatments R100, R175 or R250) was administered intravenously. The maximum suppression of the first twitch of TOF (T1) was recorded and calibrated with T1C to construct the dose–response curve, from which ED₅₀ and ED₉₅ were calculated. Time from rocuronium administration to TOF ratio/TOFRC > 0.9 (duration TOFR0.9) was recorded.ResultsED₅₀ and ED₉₅ of rocuronium during alfaxalone anesthesia were 175 and 232 μg kg^–1, respectively. The median (range) duration TOFR0.9 was longer in treatment R250 [10.1 (9.2–10.9) minutes] than in treatments R100 [3.1 (2.9–4.4) minutes; p < 0.0001] and R175 [7.7 (6.9–8.1) minutes; p < 0.0001]; and longer in treatment R175 than in treatment R100 (p < 0.0001).Conclusions and clinical relevanceThe duration of TOFR0.9 correlated positively with the dosage of rocuronium, indicating that recovery time of rocuronium was also dose-dependent in dogs anesthetized with alfaxalone. The duration TOFR0.9 of rocuronium 250 μg kg^–1 was 10 minutes during alfaxalone anesthesia in dogs.     

蔬菜根际细菌R2–2的鉴定及其抑菌活性

从云南昆明市郊蔬菜根际分离细菌,经平板对峙培养筛选出1株抑菌能力较强的菌株R2-2,通过对其进行形态观察、Biolog微生物自动鉴定系鉴定和16S rDNA序列测定及其系统发育学分析,鉴定为甲基营养型芽孢杆菌(Bacillus methylotrophicus)。对R2-2与植物病原细菌(甘蓝黑腐病菌、魔芋细菌性软腐病菌、海棠斑点病菌、水稻白叶枯病菌、水稻细菌性条斑病菌)和病原真菌(疫霉菌、尖镰孢菌、茄镰孢菌、立枯丝核菌)进行对峙试验,结果显示,R2-2对水稻白叶枯病菌和水稻条斑病菌有较强的抑菌效果,抑菌圈直径分别达6.83 cm和7.03 cm。该菌株的16S rDNA序列已在GenBank中注册,登录号为JN648098。     

Effect of Tungsten on the Growth,Dry-Matter Production,and Biochemical Constituents of Cowpea

The effects of various concentrations (0, 5, 10, 15, 20, and 25 μg g^?1) of tungsten (W) as sodium tungstate were observed on growth performance, dry-matter production, and selected biochemical constituents of cowpea. Lower applied doses of W promoted root–shoot length whereas greater doses retarded it. Chlorophyll contents and soluble sugars increased with lower applied doses of W. Greater applied doses of W resulted in an increase in the chlorophyll a/b ratio. A significant gradual decrease in proline contents was observed with lower applied doses of tungsten. Tungsten contents in plant material showed a very highly significant (P < 0.001) correlation with soil-applied tungsten.     

Earthquake impacts on a protected pinniped in New Zealand

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Impact of push–pull cropping system on pest management and occurrence of ear rots and mycotoxin contamination of maize in western Kenya

Push–pull involves intercropping of cereals with Desmodium as a “push” crop and planting Napier grass/Brachiaria as the “pull” crop at the border. The technology has been reported to effectively control stemborers, striga weed, and fall armyworm (FAW), and to improve soil nutrition, resulting in increased grain yield. This study evaluated the impact of stemborer and FAW management using this technology on incidence of maize ear rots and preharvest contamination of grains with aflatoxin and fumonisin in western Kenya. The study was conducted during three cropping seasons on maize grown under the push–pull system and as a monocrop. Incidence of stemborer and FAW damage was determined as percentage of damaged plants, while incidence of ear rots was determined as percentage of ears with symptoms. At harvest, fungi were isolated from kernels and aflatoxin and fumonisin were quantified using enzyme-linked immunosorbent assay. Stemborer and FAW damage was significantly (p = .001) reduced by over 50% under the push–pull system. There was also a significant (p < .001) reduction in the incidence of Fusarium verticillioides (60%) and Aspergillus flavus (86%), which was reflected in a reduced incidence of ear rots (50%) with the push–pull system (p = .001). Fumonisin in maize from push-pull farms was significantly (p = .048) reduced (39%) but the technology had no significant (p > .05) effect on aflatoxin. The study showed that push–pull is an effective strategy for managing maize ear rots and fumonisins, and therefore could play a role in improving food safety among smallholder maize farmers in the region.     

Where art thou louse? A snapshot of attachment location preferences in salmon lice on Atlantic salmon hosts in sea cages

Problematic sea lice infestations on farmed Atlantic salmon (Salmo salar) have motivated extensive research and development into new methods to prevent, monitor and control sea lice. Most of these technologies require detailed information on the behaviour, spatial distribution and demography of lice on host fish. This study investigated how salmon lice (Lepeophtheirus salmonis) infestation density varies across the host's surface under sea cage farming conditions. Lice abundance, demography and attachment location were tracked over time, with repeated sampling of 300 individually tagged salmon across three replicate experimental sea cages. The data reveal clear differences in attachment locations according to sex and stage, but with an overall preference for the dorsal surface among mobile stages—dorsal head for adult females and dorsal-posterior section for males and pre-adults. Total lice abundance was highly variable between repeated measures of individual fish, consistent with frequent host-switching or mortality. Total lice numbers also declined between sampling dates, likely due to handling, with lost mobile lice being almost exclusively adult males. As the distribution of sea lice on hosts is likely determined by numerous factors, future image-based automated detection systems should be validated in settings that reflect the complex host–parasite interactions that occur in open farming systems.     

Maize–legume intercropping promote N uptake through changing the root spatial distribution,legume nodulation capacity,and soil N availability

Legume cultivars affect N uptake, component crop growth, and soil physical and chemical characteristics in maize–legume intercropping systems. However, how belowground interactions mediate root growth, N fixation, and nodulation of different legumes to affect N uptake is still unclear. Hence, a two-year experiment was conducted with five planting patterns, i.e., maize–soybean strip intercropping (IMS), maize–peanut strip intercropping (IMP), and corresponding monocultures (monoculture maize (MM), monoculture soybean (MS), and monoculture peanut (MP)), and two N application rates, i.e., no N fertilizer (N–) and conventional N fertilizer (N+), to examine relationships between N uptake and root distribution of crops, legume nodulation and soil N availability. Results showed that the averaged N uptake per unit area of intercrops was significantly lower than the corresponding monocultures. Compared with the monoculture system, the N uptake of the intercropping systems increased by 31.7–45.4% in IMS and by 7.4–12.2% in IMP, respectively. The N uptake per plant of intercropped maize and soybean significantly increased by 61.6 and 31.8%, and that of intercropped peanuts significantly decreased by 46.6% compared with the corresponding monocultures. Maize and soybean showed asymmetrical distribution of roots in strip intercropping systems. The root length density (RLD) and root surface area density (RSAD) of intercropped maize and soybean were significantly greater than that of the corresponding monocultures. The roots of intercropped peanuts were confined, which resulted in decreased RLD and RSAD compared with the monoculture. The nodule number and nodule fresh weight of soybean were significantly greater in IMS than in MS, and those of peanut were significantly lower in IMP than in MP. The soil protease, urease, and nitrate reductase activities of maize and soybean were significantly greater in IMS and IMP than in the corresponding monoculture, while the enzyme activities of peanut were significantly lower in IMP than in MP. The soil available N of maize and soybean was significantly greater increased in IMS and IMP than in the corresponding monocultures, while that of IMP was significantly lower than in MP. In summary, the IMS system was more beneficial to N uptake than the IMP system. The intercropping of maize and legumes can promote the N uptake of maize, thus reducing the need for N application and improving agricultural sustainability.