我国四大矿区温石棉粉尘诱导A549细胞凋亡和周期阻滞的对比研究

通过FT-IR和XRD对四川新康、陕西陕南、甘肃阿克塞和青海茫崖四大矿区温石棉的物相成分、谱学特征进行测试分析,利用MTT法、流式细胞术检测了4种温石棉纤维粉尘染毒A549细胞后的细胞存活率、凋亡率和细胞周期分布,比较和探讨了四大矿区温石棉纤维粉尘抑制细胞增殖能力的大小及其对细胞凋亡和周期阻滞的影响。研究结果显示,四大矿区温石棉的主要物相是斜纤蛇纹石,新康温石棉成分比其他3种温石棉的复杂,阿克塞和茫崖温石棉的成分相似;四大矿区的温石棉化学基团基本相同,阿克塞和茫崖温石棉纤维的表面结构较陕南和新康温石棉的完善。4种温石棉均能不同程度地抑制A549细胞增殖,诱导细胞凋亡和周期阻滞:茫崖组凋亡率最大(22. 56±2. 56)%,陕南组凋亡率最小(19. 57±3. 07)%;细胞周期阻滞均以G2/M期阻滞为主,新康、陕南、阿克塞和茫崖组处于G2/M期细胞比例分别增加8. 90%、8. 58%、9. 13%和10. 44%。4种温石棉导致细胞凋亡和周期阻滞的能力:茫崖新康阿克塞陕南。     

并行地图叠加分析中基于数据分解的负载均衡方法研究

地图叠加分析是一种计算密集型算法,并行化计算可以加快算法执行速度。本文研究并行化地图叠加分析中的负载均衡方法。首先针对并行算法中的IO竞争情况,定义了负载均衡指数;然后基于分治法分解空间数据,将并行系统下的地理要素分而治之,将Hilbert空间索引作为集群系统中各节点分配数据的依据,最终实现并行地图叠加分析系统中的数据负载均衡,为地图叠加分析算法中的数据并行策略提供可能性。结果表明,利用空间索引分治的负载均衡方法建立索引速度快,调度系统可以将计算任务明确分配到各计算节点。     

Analysis of permanent deformations of railway embankments under repeated vehicle loadings in permafrost regions

By large-scale dynamic tests carried out on a traditional sand-gravel embankment at the Beilu River section along the Qinghai-Tibet Railroad, we collected the acceleration waveforms close to the railway tracks when trains passed. The dynamic train loading was converted into an equivalent creep stress, using an equivalent static force method. Also, the creep equation of frozen soil was introduced according to the results of frozen soil rheological triaxial tests. A coupled creep model based on a time-hardening power function rule and the Druker-Prager yield and failure criterion was established to analyze the creep effects of a plain fill embankment under repeated train loads. The temperature field of the embankment in the permafrost area was set at the current geothermal conditions. As a result, the permanent deformation of the embankment under train loading was obtained, and the permanent deformation under the train loads to the total embankment deformation was also analyzed.     

Microbiological processes in banded iron formation deposition

Banded iron formations have been studied for decades, particularly regarding their potential as archives of the Precambrian environment. In spite of this effort, the mechanism of their deposition and, specifically, the role that microbes played in the precipitation of banded iron formation minerals, remains unresolved. Evidence of an anoxic Earth with only localized oxic areas until the Great Oxidation Event ca 2·45 to 2·32 Ga makes the investigation of O₂‐independent mechanisms for banded iron formation deposition relevant. Recent studies have explored the long‐standing proposition that Archean banded iron formations may have been formed, and diagenetically modified, by anaerobic microbial metabolisms. These efforts encompass a wide array of approaches including isotope, ecophysiological and phylogeny studies, molecular and mineral marker analysis, and sedimentological reconstructions. Herein, the current theories of microbial processes in banded iron formation mineral deposition with particular regard to the mechanisms of chemical sedimentation and post‐depositional alteration are described. The main findings of recent years are summarized and compared here, and suggestions are made regarding cross‐disciplinary information still required to constrain the role of the biosphere in banded iron formation deposition.     

分布式VR-GIS海量三维空间数据存储调度模型研究

通过提取网络环境中影响三维空间数据的影响因子,从网络化三维渲染与数据流负载平衡2个方面建立基于分布式三维空间数据库性能诊断模型,实现了可承载高数据访问压力的分布式三维空间数据库模型,解决了网络环境中三维空间数据管理和存取效率低、数据流转不畅等瓶颈问题。     

基于综合因素的 WebGIS 优化加权负载均衡的研究

日益增长的海量GIS数据使得网络集群负载均衡面临着越来越大的考验,然而目前对WebGIS负载均衡的研究模型均是针对某些方面的负载问题提出解决方案,具有一定的局限性。本文基于传统加权负载均衡模型,综合考虑节点性能、数据组织、访问热点等因素,提出了基于综合因素的WebGIS优化加权负载均衡模型来处理WebGIS中出现的常见负载问题,提高网络系统整体的稳定性。     

Morphological changes in branchial mitochondria-rich cells of the teleost Paralichthys olivaceus as a potential indicator of CO2 impacts

We studied the morphological and biochemical changes of mitochondria-rich cells (MRCs) of a demersal teleost, Paralichthys olivaceus, during exposure to 0.98, 2.97 and 4.95 kPa pCO₂. The apical opening area of MRCs increased 2.2 and 4.1 times by 24 h exposure to 2.97 and 4.95 kPa pCO₂, respectively, while the cross-sectional area or density of MRCs did not change. Gill Na⁺/K⁺-ATPase activity more than doubled at 72 h and then returned to the pre-exposure level at 168 h in 0.98 kPa pCO₂, while it increased 1.7 times at 24 h at 4.95 kPa. These results indicate that the apical opening area of MRCs and the gill Na⁺/K⁺-ATPase activity may be used as an indicator of acute (up to 72 h), but not chronic, impacts of high (>1 kPa) seawater CO₂ conditions in P. olivacues. Limitations of those parameters as indices of CO₂ impacts are discussed.     

Simulation of sediment transport during flood events: laboratory work and field experiments

Abstract

This paper aims at initiating a fundamental understanding of the suspended load transport of river sediment in unsteady flow. Laboratory erosion tests as well as artificial flood experiments are used to evaluate the influence of the transient regime on the transport efficiency of the flow. The erosion experiments reveal that the transport capacity is augmented when the unsteadiness of the flow increases. However, the influence of the transient regime is counteracted by the cohesive properties of the river bed. Field experiments with artificial floods released from a reservoir into a small canal confirm these findings and show a relationship between the friction velocity and the suspended load transport. An appropriate parameter β is proposed to evaluate the impact of the transient regime on the transport of suspended sediment.     

Prediction of ultimate axial load-carrying capacity of piles using a support vector machine based on CPT data

The support vector machine (SVM) is a relatively new artificial intelligence technique which is increasingly being applied to geotechnical problems and is yielding encouraging results. In this paper SVM models are developed for predicting the ultimate axial load-carrying capacity of piles based on cone penetration test (CPT) data. A data set of 108 samples is used to develop the SVM models. These data were obtained from the literature containing pile load tests and each sample contains information regarding pile geometry, full-scale static pile load tests and CPT results. Moreover, a sensitivity analysis is carried out to examine the relative significance of each input variable with respect to ultimate strength prediction. Finally, a statistical analysis is conducted to make comparisons between predictions obtained from the SVM models and three traditional CPT-based methods for determining pile capacity. The comparison confirms that the SVM models developed in this paper outperform the traditional methods.     

简谐荷载作用下饱和土体中圆形衬砌隧道三维动力响应分析

研究了全空间饱和土体中圆形衬砌隧道在径向简谐点荷载作用下的三维动力响应,将衬砌用无限长圆柱壳来模拟,土体用Biot饱和多孔介质模型来模拟,引入两类势函数来表示土骨架的位移和孔隙水压力,并利用修正Bessel方程来求解各势函数,结合边界条件,得到频率-波数域内衬砌和土骨架位移、孔隙水压力的解答,最后进行Fourier逆变换得到时间-空间域内的响应。通过算例分析了荷载振动频率和土体渗透性对土体和衬砌位移响应及土体孔压的影响。结果表明,饱和土体和弹性土体的位移响应具有明显区别。随着荷载频率的增大,土体和隧道位移幅值减小,土体孔压幅值增大;随着土体渗透性增大,土体位移及孔压幅值减小。