Utilization of cathodically-produced hydrogen from mild steel byDesulfovibrio species with different types of hydrogenases

Summary Desulfovibrio (D.) vulgaris Hildenborough with a highly active Fe-containing periplasmic hydrogenase,D. salexigens British Guiana with a Fe–Ni–Se periplasmic hydrogenase, andD. multispirans with a Fe–Ni cytoplasmic hydrogenase utilized cathodically-produced hydrogen from mild steel as the only energy source for activity and growth. Changes on the mild steel surface occurred during growth of these bacteria. The concentration of iron sulfide, a corrosion product of mild steel, increased over time, andDesulfovibrio species had an active hydrogenase when they were grown in lactate/sulfate media. This hydrogenase may be any of the three types found in the genus,Desulfovibrio. The concentration of iron in the media affected the production and activity of the Fe-hydrogenase fromD. vulgaris Hildenborough. With an iron-limited medium, the specific activity and the total amount of the periplasmic hydrogenase was less than found with a non-iron limited media.     

High‐Performance Thickness Insensitive Perovskite Solar Cells with Enhanced Moisture Stability

High‐performance perovskite solar cells (PVSCs) with absorber layer thickness insensitive features are important for practical fabrication, however these features are difficult to be realized. There are very few reports of the fabrication of polycrystalline PVSCs with power conversion efficienies (PCE) insensitive to film thickness beyond 600 nm. The main reason lies in more serious recombination of the thick perovskite layer compared to the thin layer. Herein, this challenge is addressed by a simple hot casting method to formulate high‐quality perovskite film with enlarged grain size, high carrier mobility, and reduced defects. It is found that increasing the temperature to 70 °C can dramatically increase the film thickness and enlarge the perovskite crystal, therefore boost the efficiency from ≈16% to ≈19%. Notably, a record PCE of 19.54% is achieved with 850 nm thick perovskite film, which is among the highest efficiency for thick‐film PVSCs. The PCE remains steady around 19% when modifying the perovskite layer from 700 to 1150 nm. Moreover, these thick‐film PVSCs show good stability with 80% of its initial efficiency after 30 d in air with a humidity of 50%. Overall, this simple yet effective method has a great potential in the mass manufacture of PVSCs.     

Genes involved in copper resistance influence survival of Pseudomonas aeruginosa on copper surfaces

Aims:  To evaluate the killing of Pseudomonas aeruginosa PAO1 on copper cast alloys and the influence of genes on survival on copper containing medium and surfaces.
Methods and Results:  Different strains of P. aeruginosa were inoculated on copper containing medium or different copper cast alloys and the survival rate determined. The survival rates were compared with rates on copper-free medium and stainless steel as control. In addition, the effect of temperature on survival was examined.
Conclusions:  Copper cast alloys had been previously shown to be bactericidal to various bacteria, but the mechanism of copper-mediated killing is still not known. In this report, we demonstrate that P. aeruginosa PAO1 is rapidly killed on different copper cast alloys and that genes involved in conferring copper resistance in copper-containing medium also influenced survival on copper cast alloys. We also show that the rate of killing is influenced by temperature.
Significance and Impact of the Study:  To use copper surfaces more widely as bactericidal agents in various settings, it is important to understand how genes influence survival on these surfaces. Here we show that genes shown to be involved in copper resistance in P. aeruginosa PAO1 can have an impact on the length of survival time on copper cast alloys under certain conditions. This is an important first step for evaluation of future use of copper surfaces as bactericidal agents.     

3-Dimensional Resin Casting and Imaging of Mouse Portal Vein or Intrahepatic Bile Duct System

In organs, the correct architecture of vascular and ductal structures is indispensable for proper physiological function, and the formation and maintenance of these structures is a highly regulated process. The analysis of these complex, 3-dimensional structures has greatly depended on either 2-dimensional examination in section or on dye injection studies. These techniques, however, are not able to provide a complete and quantifiable representation of the ductal or vascular structures they are intended to elucidate. Alternatively, the nature of 3-dimensional plastic resin casts generates a permanent snapshot of the system and is a novel and widely useful technique for visualizing and quantifying 3-dimensional structures and networks.A crucial advantage of the resin casting system is the ability to determine the intact and connected, or communicating, structure of a blood vessel or duct. The structure of vascular and ductal networks are crucial for organ function, and this technique has the potential to aid study of vascular and ductal networks in several ways. Resin casting may be used to analyze normal morphology and functional architecture of a luminal structure, identify developmental morphogenetic changes, and uncover morphological differences in tissue architecture between normal and disease states. Previous work has utilized resin casting to study, for example, architectural and functional defects within the mouse intrahepatic bile duct system that were not reflected in 2-dimensional analysis of the structure^1,2, alterations in brain vasculature of a Alzheimer''s disease mouse model³, portal vein abnormalities in portal hypertensive and cirrhotic mice⁴, developmental steps in rat lymphatic maturation between immature and adult lungs⁵, immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury⁶.Here we present a method of generating a 3-dimensional resin cast of a mouse vascular or ductal network, focusing specifically on the portal vein and intrahepatic bile duct. These casts can be visualized by clearing or macerating the tissue and can then be analyzed. This technique can be applied to virtually any vascular or ductal system and would be directly applicable to any study inquiring into the development, function, maintenance, or injury of a 3-dimensional ductal or vascular structure.     

Complex In-Substrate Dinosaur (Sauropoda,Ornithopoda) Foot Pathways Revealed by Deep Natural Track Casts from the Lower Cretaceous Xiagou and Zhonggou Formations,Gansu Province,China

Several new Early Cretaceous tracksites from the Lower Cretaceous Xiagou Formation of Gansu Province (China) with tracks of large sauropods and ornithopods are described. Previously reported bird tracks were missing due to human negligence. The studied specimens are preserved as impressions and shallow and deep natural track casts. These dinosaur tracks are first reported from the Jiuquan area in the Changma Basin, matching well with the skeletal record of diverse non-avian dinosaur-bird faunas of this region. Moreover, they add new data to the dinosaur ichnofaunas of the Lanzhou-Minhe Basin (Gansu Province) and indicate a wide distribution of dinosaur-bird assemblages in the Early Cretaceous. Regarding morphology, sauropod, and ornithopod tracks from the Lanzhou-Minhe Basin and the Jiuquan area are very similar to each other. Titanosauriform trackmakers are assumed for the sauropod tracks and possibly iguanodontids have left the large, tridactyl ornithopod tracks. Of particular interest are well-preserved, deep natural track casts of large ornithopods and sauropods preserving ridges and grooves as well as striation marks on the lateral sides of the casts that allow the reconstruction of complex pathways of the foot within the substrate. One particular sauropod pes–manus track cast even indicates lateral and vertical sliding within the sediment because of the presence of “double impressions of digits” on the bottom.     

Nest architecture of the leaf-cutting ant <Emphasis Type="Italic">Acromyrmex rugosus rugosus</Emphasis>

The prominent nests mounds of many ant species are one of the most obvious signs of their presence, yet the subterranean architecture of nests is often poorly known. The present work aimed to establish the external and internal structure of nests of a species of leaf-cutting ant, Acromyrmex rugosus rugosus, by either marking the interior of nests with talcum powder, or forming casts with cement. Twelve nests were excavated and surveyed, with eight being marked with talcum powder and four cast with cement. The external and internal structure of the nests was highly variable. The largest and smallest nests had mound areas of 9.89 m² and 0.01 m² respectively. The number of chambers found ranged from 1 to 26, with maximum dimensions of between 6 and 70 cm. Chambers were found close to the soil surface (6 cm) down to a maximum depth of 3.75 m. In addition to chambers containing fungus garden, some chambers were found to be empty, filled with soil or filled with waste, the first time this has been recorded in a species of Acromyrmex. The nests of A. rugosus rugosus appear to be unusually complex for the genus, containing a diversity of irregular chambers and tunnels. Received 21 December 2006; revised 30 May 2007; accepted 1 June 2007.     

中型兽类头部标本的剥制技术

简要介绍了欧美国家的中型兽类头部标本剥制技术,包括制作前的构思和记录、头部测量部位、头部皮层剥制、皮张处理、头模的制作、安装义眼、制作假耳、头部模型和角的连接、披皮操作和整形等技术。     

老化和风干处理对蚓粪微生物学性质和结构稳定性的影响

蚓粪水稳性团聚体含量是结构稳定性表征之一,蚓粪中水稳性团聚体含量与其微生物学性质是紧密联系的,并且受到老化时问和有机质等因素的影响。国内将蚓粪水稳性团聚体含量与其微生物学性质联系,并结合施用不同有机物处理的研究很少见报道。研究通过室内短期培养试验,研究了在不同碳氮比有机物施用下蚓粪老化和风干处理对其微生物生物量、微生物活性和结构稳定性变化的影响。研究结果表明蚓粪经过老化处理后真菌数量、微生物生物量碳和微生物活性都显著降低。不同有机物的施用对蚓粪微生物学性质的影响主要表现在施用牛粪的处理中蚓粪细菌数量高于施用秸秆的处理,真菌数量相反。新鲜蚓粪经过老化处理后总的水稳性团聚体含量（〉0．053mm）增加,主要表现在水稳性大型大团聚体（〉2mm）含量增加,且在施用牛粪的处理中达到显著,可能是与牛粪比秸秆能分解产生更多的粘结物质有关。蚓粪的风于处理也显著增加各个处理中总水稳性团聚体含量,且风干后蚓粪中水稳性团聚体主要以微团聚体（0．25～0．053mm）形式存在。施用秸秆的处理中,新鲜蚓粪0．25～0．053mm粒级的水稳性团聚体含量显著高于施用牛粪的处理。经风干后,施用秸秆的处理0．25～0．053mm的水稳性团聚体含量显著低于施用牛粪的处理,而水稳性大型大团聚体含量显著高于施用牛粪的处理。蚓粪的不同粒级水稳性团聚体含量和蚓粪的生物学性质之间存在良好的相关性。     

水溶性有机物对黑麦草吸收铜的影响

采用水培试验,研究蚓粪及蚯蚓培养载体牛粪中水溶性有机物(DOM)对不同Cu2+浓度下(0、5、10 mg·L-1)黑麦草吸收Cu2+的影响.结果表明:随着Cu2+浓度的增加,黑麦草地上部、根干质量,以及根系的长度、表面积、体积和根尖数均逐渐下降;DOM显著增加了Cu2+处理下黑麦草地上部及根系生物量,促进了其根系的长度、表面积、体积和根尖数的增长.DOM降低了黑麦草地下部Cu2+浓度,促进了Cu2+从地下部向地上部的运输,显著增加了地上部Cu2+积累量.蚓粪DOM对黑麦草的影响优于牛粪DOM,并且供试高浓度DOM效果优 于低浓度.     

Mineral nitrogen cycling through earthworm casts in a grazed pasture under elevated atmospheric CO2

We used the New Zealand grazed pasture free air CO₂ enrichment experiment to determine the effects of elevated CO₂ on earthworm (Aporrectodea caliginosa and Lumbricus rubellus) cast production and mineral nitrogen (N) concentration over a 5‐week period in the spring. Elevated CO₂ did not affect earthworm biomass or the amount of cast material produced. However, cast mineral N concentrations were 18% lower, resulting in 27% less mineral N being deposited on the soil surface under elevated CO₂. An analysis of the earthworms' potential diet showed that a reduction in the N content of sheep dung at elevated CO₂ was the most likely cause of the lower cast N concentrations. Earthworm casts made only a small contribution to mineral N cycling in our system; however, their quality may act as a sensitive indicator of reduced N availability under elevated CO₂ which is consistent with the hypothesised process of progressive N limitation.