Body temperature and body size affect flight performance in a damselfly

Flight performance is undoubtedly an important factor for behavioral success in flying insects. Though it is well-known that the flight performance is influenced by body temperature and body size, the relative importance of these factors is not well-understood. We performed laboratory experiments using the male-polymorphic damselfly Mnais costalis with larger territorial males and smaller non-territorial males in a population. We analyzed the effects of body temperature and body size, measured as the thoracic temperature and left hind-wing length, respectively, on two indices of flight performance: maximum lifting force and size-corrected lifting force. The latter is an index of acceleration that is related to aerial agility. The results showed that higher body temperature produced both larger maximum lifting force and larger size-corrected lifting force. In contrast, while larger size produced a larger maximum lifting force, it produced a lower size-corrected lifting force. The results of field measurements showed that territorial males had variable thoracic temperatures depending on the insolation in their territories. In contrast, non-territorial males had less variable and generally higher thoracic temperatures than territorial males as they are mostly found in sunny spots. Until now, the influence of body temperature on behavioral performance has remained unclear although considerable studies have suggested such influence. We showed, here, for the first time, combined effects of body size and body temperature on flight performance. We also showed that body temperature was influenced by the mating strategies of a damselfly. These findings provide new insights into the cost and benefits of territorial behavior in ectothermic animals.     

摩托车防护头盔发展现状和展望分析

当今保护人类健康安全日益受到社会普遍重视,头部安全是摩托车乘员的首要问题。摩托车头盔防护依然十分重要;国际上其标准修定较快并不断完善;通过对TBT通报,头盔安全类发明专利等数据分析,得出摩托车头盔的技术研发高峰近期爆发。     

Arsenic compounds accumulated in pearl oyster Pinctada fucata

We investigated the water-soluble arsenic compounds present in the soft tissues of both the pearl-free and the pearl-containing pearl oysters. After dividing the soft tissue into five parts, i.e., adductor muscle, foot, mantle, viscera and gill, each part was analyzed by high-performance liquid chromatography-inductively coupled plasma mass spectrometry for the arsenic compounds accumulated in it. Arsenic concentration of each tissue part ranged from 22.1 to 45.7 microg g(-1) of dry tissue in the pearl-free pearl oyster and from 27.4 to 50.4 microg g(-1) of dry tissue in the pearl-containing pearl oyster. On the grounds of the present evidence the major water-soluble arsenic compound accumulated in each part was identified as arsenobetaine without exception in both types of pearl oysters (94.3-99.7% in the pearl-free pearl oyster and 87.2-99.7% in the pearl-containing pearl oyster). Trace or small amounts of arsenic compounds including tetramethylarsonium ion and arsenocholine were also detected in some parts. The levels of these minor arsenicals were a little higher in pearl-free pearl oyster than in the pearl-containing pearl oyster. This study confirms the hygienic safety of the soft tissues of both the pearl-free and the pearl-containing pearl oysters, as food.     

Design considerations of constructed wetlands to reduce landfill leachate contamination in tropical regions

In tropical regions, landfill leachate contamination at municipal solid waste disposal sites is a critical issue because of the large volume of highly contaminated leachate formed during the rainy season. We evaluated the efficacy of constructed wetlands (CWs) with the ability to reduce the water volume and pollutant levels to reduce leachate contamination compared to the most commonly used treatment system, stabilization ponds, based on parameters obtained in a field experiment in Thailand. The simulation indicated that CWs had a higher potential to reduce the water volume than stabilization ponds over the course of a year. Scenario evaluations under varying initial water depths, system depths, and area sizes indicated that the CWs could reduce the treatment area to prevent overflow and leachate pollution. In addition, the CWs were estimated to reduce the leachate amount and pollution by 83–100% and 92–99%, respectively. When there is limited land available, deeper CWs can be used to sustainably prevent contamination from leachate overflow. Effectively designed CW systems may be valuable for both reducing the required area and the contamination; therefore, CWs are a promising option for sustainable landfill leachate treatment systems in developing tropical regions.     

Correction to: Design considerations of constructed wetlands to reduce landfill leachate contamination in tropical regions

Journal of Material Cycles and Waste Management - In the original publication of the article, Eq. 5 was published incorrectly. The correct equation is given below.     

Hydrolysis of di-n-butyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate in human liver microsomes

Diester phthalates are industrial chemicals used primarily as plasticizers to import flexibility to polyvinylchloride plastics. In this study, we examined the hydrolysis of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in human liver microsomes. These diester phthalates were hydrolyzed to monoester phthalates (mono-n-butyl phthalate (MBP) from DBP, mono-n-butyl phthalate (MBP) and monobenzyl phthalate (MBzP) from BBzP, and mono(2-ethylhexyl) phthalate (MEHP)) by human liver microsomes. DBP, BBzP and DEHP hydrolysis showed sigmoidal kinetics in V-[S] plots, and the Hill coefficient (n) ranged 1.37-1.96. The S₅₀, V_max and CL_max values for DBP hydrolysis to MBP were 99.7 μM, 17.2 nmol min⁻¹ mg⁻¹ protein and 85.6 μL min⁻¹ mg⁻¹ protein, respectively. In BBzP hydrolysis, the values of S₅₀ (71.7 μM), V_max (13.0 nmol min⁻¹ mg⁻¹ protein) and CL_max (91.3 μL min⁻¹ mg⁻¹ protein) for MBzP formation were comparable to those of DBP hydrolysis. Although the S₅₀ value for MBP formation was comparable to that of MBzP formation, the V_max and CL_max values were markedly lower (<3%) than those for MBzP formation. The S₅₀, V_max and CL_max values for DEHP hydrolysis were 8.40 μM, 0.43 nmol min⁻¹ mg⁻¹ protein and 27.5 μL min⁻¹ mg⁻¹ protein, respectively. The S₅₀ value was about 10% of DBP and BBzP hydrolysis, and the V_max value was also markedly lower (<3%) than those for DBP hydrolysis and MBzP formation for BBzP hydrolysis. The ranking order of CL_max values for monoester phthalate formation in DBP, BBzP and DEHP hydrolysis was BBzP to MBzP ? DBP to MBP > DEHP to MEHP > BBzP to MBP. These findings suggest that the hydrolysis activities of diester phthalates by human liver microsomes depend on the chemical structure, and that the metabolism profile may relate to diester phthalate toxicities, such as hormone disruption and reproductive effects.     

Evolution of water chemistry in natural acidic environments in Yangmingshan,Taiwan

In Yangmingshan National Park, located in the northern part of the Taiwan Island, there is a very rare area where fish (Channa asiatica) live in spite of acid environments. The origin of the acid in local acid ponds and rivers and the evolution of the water chemistry are discussed on the basis of sulfur stable isotope ratios and chemical equilibria. One of the sources of the acid is sulfuric acid, which is derived from the oxidation of hydrogen sulfide in volcanic gas gushing out from fumaroles around the area and from acid deposition supplied from Taipei City. It is also derived from the oxidation of pyrite: the sulfur stable isotope ratios of delta 34S of +1@1000 to +4@1000 (relative to CDT) of sulfate in acid pond waters (pH 3-4) could be related to those of hydrogen sulfide in volcanic gas, pyrite in local pond sediments and soils, and sulfate in rain water. One acid source is sulfuric and hydrochloric acids arising in springs from geothermal activity: the delta 34S values were characterised by +13@1000 to +17@1000 sulfate-S, which was provided by a disproportionation reaction of sulfur dioxide in the depths. Another acid source could be the oxidation of iron(II). Under acidic conditions, the water-rock reaction gives rise to high concentrations of aluminium and iron. While flowing down surface streams, iron(II) is oxidised to iron(III) and then hydrolysed to cause further acidification under oxic conditions. The concentrations of iron and aluminium are controlled by redox and dissolution equilibria.