电感耦合等离子体质谱法测定地表水中铊的研究

本研究建立了电感耦合等离子体质谱法(ICP-MS)测定地表水中铊的方法。对仪器工作条件进行了优化,用在线内标校正基体效应的干扰,重点考察了样品测定介质、酸度、共存元素干扰等因素对测定结果的影响。在最佳实验条件下,该方法的检出限可达0.003μg/L,线性相关系数不小于0.999 9,加标回收率为93%~110%。与传统的原子吸收法相比,该方法不需要富集等繁琐的前处理过程,具有检出限低、快速、精密度和准确度高等优点。     

典型地铁车站结构大型振动台试验相似比分析

以典型地铁车站结构的大型振动台试验为基础,对试验相似比设计和试验结果的相似比精确度进行了分析。基于Buckinghamπ定理,采用一致相似率分析方法,建立以覆土质量为主要控制因素的等效密度方程。将需要施加的人工配重与非结构荷载统一考虑,分析地铁地下结构欠人工质量模型的相似比。研究不同的覆土厚度对重力效应的影响程度,计算了试验中的实际相似比,并通过试验测试结果证明其在提高计算精度上的有效性。结果表明,随着结构上覆土层厚度的增加,速度、频率、加速度的重力效应与人工质量模型的重力效应越接近,且加速度重力效应精度的提高幅度最大。通过调整试验条件下实际覆土层厚度,反演实际相似比,可以有效提高相似比设计的精确度。     

宋代关中地区旱灾研究

通过对宋代关中平原历史文献资料的整理和分析,来了解此时关中平原干旱灾害的年度变化、等级差异、发生季节、地区间的频次分布情况。据统计,宋代关中平原从公元960年至1279年,共319年,发生旱灾95次,平均每3.3年发生一次;旱灾频次在宋代早、中、晚期变化不均,早期发生频次最多,中期最少,晚期较少,但变幅较大。旱灾主要集中于春、夏两季;空间上关中自东向西灾害频次逐渐增多。在旱灾等级分布上,可划分为小、中、大、特大四级灾害,各占40%、35%、17%、8%。旱灾频发的原因主要有降水和气候异常波动、地形位置、人口增加、政治战争等。     

水稻秸秆生物炭对水体中DDE的吸附性能研究

通过模拟实验,初步考察了一款水稻秸秆生物炭对水中滴滴涕农药的吸附效应。吸附动力学与吸附等温线的结果表明,水稻秸秆生物炭对水中滴滴涕具有吸附速度快、吸附容量高的特点,在水体有机污染物防治中具有较好应用前景。     

我国与国外民间直升机救援的比较研究

本文通过对国外和我国民间直升机的救援现状进行分析,从救援装备、专业人才、基础设施、政策法规、运营模式等方面做了对比研究,发现我国在各方面都存在较大差距,提出了构建我国民间直升机救援体系的具体措施。     

Bone histology sheds light on the nature of the “dermal armor” of the enigmatic sauropod dinosaur <Emphasis Type="Italic">Agustinia ligabuei</Emphasis> Bonaparte, 1999

Agustinia ligabuei is an Early Cretaceous sauropod dinosaur from the northwest of Patagonia that is currently the topic of debate with respect to its phylogenetic position and atypical dermal armor. The presence of four morphotypes of laminar and transversely elongated putative osteoderms was used to consider Agustinia as an armored sauropod. Regarding the different hypotheses about the identity of the bony structures of Agustinia (e.g., osteoderms, cervical or dorsal ribs, hypertrophied elements), a comparative histological analysis has been carried out. Histological evidence is presented herein and reveals that none of the morphotypes of Agustinia shows a primary bone tissue formed by structural fiber bundles as in other sauropod dinosaur osteoderms. Furthermore, on the basis of their gross morphology and microstructure, the bony structures originally classified as types 1 + 4 and 3 are more comparable respectively with dorsal and cervical ribs than any other kind of dermal or bony element. Due to poor preservation, the nature of the type 2 cannot be assessed but is here tentatively assigned to a pelvic girdle element. Although a phylogenetic reassessment of Agustinia is not the purpose of this paper, our paleohistological analyses have broader implications: by not supporting the dermal armor hypothesis for Agustinia, its inclusion in Lithostrotia is not justified in the absence of other diagnostic features.     

Tail regeneration affects the digestive performance of a Mediterranean lizard

In caudal autotomy, lizards shed their tail to escape from an attacking predator. Since the tail serves multiple functions, caudal regeneration is of pivotal importance. However, it is a demanding procedure that requires substantial energy and nutrients. Therefore, lizards have to increase energy income to fuel the extraordinary requirements of the regenerating tail. We presumed that autotomized lizards would adjust their digestion to acquire this additional energy. To clarify the effects of tail regeneration on digestion, we compared the digestive performance before autotomy, during regeneration, and after its completion. Tail regeneration indeed increased gut passage time but did not affect digestive performance in a uniform pattern: though protein income was maximized, lipid and sugar acquisition remained stable. This divergence in proteins may be attributed to their particular role in tail reconstruction, as they are the main building blocks for tissue formation.     

Safe caves and dangerous forests? Predation risk may contribute to salamander colonization of subterranean habitats

Recent studies suggest that many organisms actively colonize the subterranean environment to avoid climatic stress, exploit new ecological opportunities and reduce competition and predation. Terrestrial salamanders are known to colonize the more stable subterranean habitats mainly to escape external climatic extremes, while the role of predation avoidance remains untested. To better understand the importance of predation, we used clay models of the cave salamander Speleomantes strinatii to compare the predation occurring in woodland and subterranean habitats. Models were positioned in three forests and in three caves in NW Italy. One-hundred eighty-four models were retrieved from the field and 59 (32%) were attacked by predators. Models were attacked on their head more often than expected by chance and, therefore, were perceived by predators as real prey items. In the woodlands, clay models showed a four-time higher probability of being attacked in comparison to caves, suggesting a different level of potential predation risk in these surface habitats. These findings are one of the first experimental evidences that, in terrestrial ecosystems, predation avoidance may contribute to the salamander underground colonization process.     

Temporal variation in size-assortative mating and male mate choice in a spider with amphisexual care

Males should be more selective when they have a high investment in reproduction, especially in species with biparental or paternal care. In this context, male mate choice can promote size-assortative mating (SAM) when (1) large males win intrasexual disputes, (2) large females are more fecund, and (3) males prefer larger females to smaller ones. In the spider Manogea porracea, males exhibit high reproductive investment by building their webs above those of females and exhibiting extended care of offspring in the absence of females. Under these circumstances, we expect the occurrence of SAM and male preference for large females. Herein, we performed observations and experiments in the field to evaluate the hypotheses that (1) M. porracea mates assortatively by size and (2) SAM is influenced by male mate choice. Furthermore, we measured variables that could affect mating patterns, the sex ratios, and densities of both sexes. Pairing in M. porracea was positively size-assortative in 2012, but not in 2013. Large males won most disputes for mates and preferred larger females, which produced more eggs. The inconsistency in detection of SAM was due to population dynamics, namely variations in sex ratio and population density across the breeding season. Furthermore, we found that the significance of male mate choice on sexual selection of body size in M. porracea strongly depends on the competition intensity for mating opportunities. The traditional sexual selection hypothesis of SAM needs to be reviewed and must include measures of competition intensity.