Infrared spectroscopic characterization of dehydration and accompanying phase transition behaviors in NAT-topology zeolites

Relative humidity ( P_{\textH 2 \textO} P_{{{\text{H}}_{ 2} {\text{O}}}} , partial pressure of water)-dependent dehydration and accompanying phase transitions in NAT-topology zeolites (natrolite, scolecite, and mesolite) were studied under controlled temperature and known P_{\textH 2 \textO} P_{{{\text{H}}_{ 2} {\text{O}}}} conditions by in situ diffuse-reflectance infrared Fourier transform spectroscopy and parallel X-ray powder diffraction. Dehydration was characterized by the disappearance of internal H₂O vibrational modes. The loss of H₂O molecules caused a sequence of structural transitions in which the host framework transformation path was coupled primarily via the thermal motion of guest Na⁺/Ca²⁺ cations and H₂O molecules. The observation of different interactions of H₂O molecules and Na⁺/Ca²⁺ cations with host aluminosilicate frameworks under high- and low- P_{\textH 2 \textO} P_{{{\text{H}}_{ 2} {\text{O}}}} conditions indicated the development of different local strain fields, arising from cation–H₂O interactions in NAT-type channels. These strain fields influence the Si–O/Al–O bond strength and tilting angles within and between tetrahedra as the dehydration temperature is approached. The newly observed infrared bands (at 2,139 cm⁻¹ in natrolite, 2,276 cm⁻¹ in scolecite, and 2,176 and 2,259 cm⁻¹ in mesolite) result from strong cation–H₂O–Al–Si framework interactions in NAT-type channels, and these bands can be used to evaluate the energetic evolution of Na⁺/Ca²⁺ cations before and after phase transitions, especially for scolecite and mesolite. The 2,176 and 2,259 cm⁻¹ absorption bands in mesolite also appear to be related to Na⁺/Ca²⁺ order–disorder that occur when mesolite loses its Ow4 H₂O molecules.     

β-环糊精包合态三氟氯氰杀虫剂的制备

为了进一步提高三氟氯氰菊酯农药的防治效果。寻找适宜的农药新剂型，我们用液相法制备了三氟氯氰菊酯－β－环糊精包合物，并以水为基质进行了稳定性观察，同时又以差热分析法和气相色谱法确认了包合物的形成，以旋光度法证明两者间的包合比。结果表明，三氟氯氰菊酯与β-环糊精可形成1：1型包合物，该包合物稳定性高，具有一定的水溶性，而且在水中稳定，所以有望通过环糊 包合作用将三氟氯氰菊酯帛成水剂；当以气相法测试包合态三氟氯氰菊酯含量时，必须将其解络，使之成为游离状态，然后按常规方法进行含量测定。     

Analysis on the decadal scale variation of the dust storm in North China

Dust storm is a disastrous weather that can cause serious environmental consequences and hazards. It causes excessive soil mass and nutrient loss in source areas, and air pollution in deposition area, which result in bad influence on agriculture, industry, traffic, and peoples’ daily life[1-4]. Dust storm can also affect the thermal balance of planetary radiation and then lead to meso- to macroscale climatic modification[5-7]. North- west China and North China are two high-frequency centers …     

The Pindos Fold-and-thrust belt (Greece): inversion kinematics of a passive continental margin

Continuous exposure in the Pindos mountain chain (Greece) and the detailed stratigraphic measurements in the area enable us to construct eight balanced cross sections across the Pindos Fold-and-thrust belt (PFTB) and to approach quantitatively some parameters which controlled foreland evolution. The 160-km-wide passive continental margin of the Apulian continent in Greece was progressively shortened from east to west at rates of 6 mm/year between the Early Oligocene and Late Eocene. From the rear to the frontal part of the wedge, fault-bend folds, duplexes and imbricates were formed, while strain was partitioned into faulting (~34%), layer parallel shortening (~23%) and buckling (~9%). Foreland subsidence and internal deformation of the orogenic wedge are strongly affected by two parameters of equal importance: the thrust load of the overthrusted microcontinents and the rigidity of the underthrusted Apulian passive margin. Changes in the thickness of the pre-orogenic sediments and reactivated transform faults induced salients. During the Lower Miocene, the orogenic wedge in the Peloponnese suffered additional uplift and westward gravitational gliding induced by the intracontinental subduction of the Palaeozoic rift zone of the Phyllite-Quartzite Series, which was reactivated and returned to the earths surface during the Hellenic orogeny.     

Determining the equivalent permeability tensor for fractured rock masses using a stochastic REV approach: Method and application to the field data from Sellafield,UK

A numerical procedure to determine the equivalent permeability tensor of a fractured rock is presented, using a stochastic REV (Representative Elementary Volume) concept that uses multiple realizations of stochastic DFN (Discrete Fracture Network) models. Ten square DFN models are generated using the Monte Carlo simulations of the fracture system based on the data obtained from a site characterization program at Sellafield, Cumbria, UK. Smaller models with varying sizes of from 0.25 m×0.25 m to 10 m×10 m are extracted from the generated DFN models and are used as two-dimensional geometrical models for calculation of equivalent permeability tensor. The DFN models are also rotated in 30º intervals to evaluate the tensor characteristics of calculated directional permeability. Results show that the variance of the calculated permeability values decreases significantly as the side lengths of the DFN models increase, which justifies the existence of a REV. The REV side length found in this analysis is about 5 m and 8 m with 20% and 10% acceptable variations, respectively. The calculated directional permeability values at the REV size have tensor characteristic that is confirmed by a close approximation of an ellipse in a polar plot of the reciprocal of square roots of the directional permeability.

Two-dimensional dam break flooding simulation: a GIS-embedded approach

In the twenty-first century, around 200 notable dam and reservoir failures happened worldwide causing massive fatalities and economic costs. In order to reduce the losses, managers usually define mitigation strategies identifying flooding area due to dam break by using standalone hydrodynamic models and then importing the results within a GIS to perform risk analysis. This two-step procedure is time expensive, error prone due to export/import requirements and not user friendly. For this reason with this work, a new numerical model for the solution of the two-dimensional dam break problem has been implemented in the GRASS GIS with a GIS-embedded approach. The model solves the conservative form of the 2D shallow water equations using a finite volume method; the intercell flux is computed by one-side upwind conservative scheme extended to a two-dimensional problem. The newly developed GIS module, among others outputs, allows to derive maximum intensity maps that can be directly used for risk assessment. Finally, the model has been (1) tested against two standard synthetic problems referenced in literature showing differences in estimated water depth of 2, 3 and 15% and (2) verified against official flooding map of an existing dam (Verzasca) detecting 75% of similarity. The problem formulation, the new GRASS module and its validation is presented.     

Migrating sand waves

A simple mathematical model is described, which reproduces the major features of sand waves' appearance and growth and in particular predicts their migration speed. The model is based on the linear stability analysis of the flat configuration of the sea bottom subject to tidal currents. Attention is focused on the prediction of the complex growth rate that bottom perturbations undergo because of both oscillatory fluid motions and residual currents. While the real part _r of controls the amplification or decay of the amplitude of the bedforms, the imaginary part _i is related to their migration speed. Previous works on the migration of the sand waves (Németh etal. 2002) consider a forcing tide made up by the M2 constituent (oscillatory period equal to 12 h) plus the residual current Z0 and predict always a downcurrent migration of the bedforms. However, field cases exist of upcurrent-migrating sand waves (downcurrent/upcurrent-migrating sand waves mean bedforms moving in the direction of the steady residual tidal current or in the opposite direction, respectively). The inclusion of a tide constituent characterized by a period of 6 h (M4) is the main novelty of the present work, which allows for the prediction of the migration of sand waves against the residual current Z0. Indeed, the M4 tide constituent, as does also the residual current Z0, breaks the symmetry of the problem forced only by the M2 tide constituent, and induces sand-wave migration. The model proposed by Besio etal. (2003a) forms the basis for the present analysis. Previous works on the subject (Gerkema 2000; Hulscher 1996a,b; Komarova and Hulscher 2000) are thus improved by using a new solution procedure (Besio etal. 2003a) which allows for a more accurate evaluation of the growth rate for arbitrary values of the parameter r, which is the ratio between the horizontal tidal excursion and the perturbation wavelength. Responsible Editor: Jens Kappenberg     

应用通量方差法估算戈壁绿洲下垫面湍流通量的研究

利用“绿洲系统能量与水分循环过程观测试验” 2005年绿洲、戈壁点的观测资料, 分析与讨论了温度、水汽的归一化标准差随稳定度变化的通量方差关系, 应用通量方差法对感热、 潜热通量进行了计算, 并同涡动相关系统的观测结果进行了比较。不稳定条件下, 戈壁点温度归一化标准差随稳定度变化的通量方差关系优于下垫面非均匀性更强的绿洲点, 绿洲点水汽的归一化标准差随稳定度变化的通量方差关系较温度量表现得更好。对同一站点, 归一化温度标准差的通量方差关系并不总是优于水汽的通量方差关系, 其取决于该站点的温度以及水汽的源汇分布情况; 通量方差法对两个站点的感热、 潜热通量均有较好的再现, 但戈壁点感热通量的计算效果优于非均匀性更强的绿洲点。应用通量方差法对潜热通量计算时若采用直接观测的感热通量, 则潜热通量的计算效果具有一定程度的改善。     

Disaster risk reduction on non-sovereign islands: La Réunion and Mayotte,France

The Islands of Réunion and Mayotte are French territories in the Indian Ocean and are prone to numerous and recurrent hazards as well as to increasing vulnerabilities. This paper examines disaster risk reduction on non-sovereign islands through the case studies of Réunion and Mayotte. The approach used is embedded in standard geographical approaches to risk analysis, focusing on place-based vulnerability, in order to understand disaster risk and disaster risk reduction on both islands. In addition to establishing baseline information and visiting both islands for further data, 21 semi-structured individual interviews were completed to understand the people’s perceptions of the hazards and of their vulnerabilities. Disaster risk reduction strategies, and attitudes from governing bodies implementing the strategies, tend to assume similar vulnerability contexts as mainland France, despite obvious differences on the islands. Many policies are implemented in a top–down manner by those from mainland France who have little interest in, and who do not fully take into consideration, local realities. This paper contributes new case studies to the literature, especially in comparing two non-Anglophone non-sovereign islands, and reinforces recommendations factoring in local contexts when addressing ‘vulnerability of a place’ to disasters.     

潘集煤矿二叠纪主采煤层中微量元素亲和性研究

安徽淮南煤田位于华北地台南端 ,发育了华北地区二叠纪含煤岩系中层位最高的可采煤层。采用仪器中子活化分析法 (INAA)测试了淮南煤田潘集煤矿二叠纪主采煤层 13个样品的 36个微量元素的浓度分布 ,并对其共生组合特点、地球化学特征及稀土元素配比模式作了初步分析 ,结果表明 ,煤中不同微量元素显示出不同的亲和性质。元素Br,As ,Sb ,Ni和Co等趋于在煤中富集 ,其中Br的有机亲和性最大。元素Na ,K ,Rb ,Th ,Hf,Zr ,Ta和REE则在煤层与顶底板接触带的碳质泥岩中富集 ,表现出与细粒陆源碎屑物更强的亲和性。其它元素倾向性不甚明显 ,但Fe ,Ca ,Sr ,HREE等元素在海水影响强度增大的煤层中含量增加。元素As,Cs,Ni,Fe和Ca在煤层中含量变化较大 ,其变异系数大于 1,其它元素则相对稳定 ,表明同一矿区煤层中微量元素含量在不受其它地质作用明显叠加影响时具有一定的稳定性。本区煤层稀土元素配比模式与华北其它地区C—P纪煤基本类似 ,普遍存在Eu亏损现象。 ∑REE在煤中分布范围为30× 10 -6～ 95× 10 -6,在顶板泥岩中超过 2 0 0× 10 -6。煤层中部 ∑REE降低 ,HREE相对富集。聚类分析表明 ,元素As ,Se ,Ag和Fe关系密切 ,这与煤中黄铁矿等成岩矿物有直接关系 ,泥炭沼泽演化期间或之后海水的直接或间接影响会促使这