Low-temperature crystal structures of stibnite implying orbital overlap of Sb 5s2 inert pair electrons

The crystal structure of stibnite [Sb₂S₃, Pnma, a=11.314(2), b=3.837(2), c=11.234(3) Å, V= 487.7(3) ų at 293 K] was refined in situ at 230, 173, and 128 K. It is a major characteristic of the structure that the Sb–S secondary bonds enclosing Sb 5s² inert lone-pair electrons at 293 K are significantly shorter than the corresponding sum of the Sb and S van der Waals radii. Concerning the temperature dependence, although both the polyhedral volume and the cation eccentricity of the two SbS₇ polyhedra exhibit continuous contractions with decreasing temperature, the sphericity values remain constant, indicating isotropic shrinkage. Consequently, the geometries of Sb 5s² inert lone-pair electrons and ligand atoms remain unchanged at low temperatures. This is because the crystal structure of stibnite at low temperature induces contraction with attractive interactions, which is called the orbital overlap between Sb 5s² inert lone-pair electrons and ligand orbitals to maintain the coordination environment. In this case, Sb 5s² lone-pair electrons are not inert, but active. Such orbital overlaps of inert lone-electron pairs can provide a reasonable explanation for shorter secondary bonds and lower band gap energy of the binary compounds containing heavy elements such as Sb, Te, Pb, and Bi, which are key factors in tracing the origins of color, luster, and semiconductivity of their minerals or compounds.     

Rapid report of June 1, 2022 MW 5.9 Lushan earthquake,China with geodetic and teleseismic data

Timely response to earthquake characterization can facilitate earthquake emergency rescue and further scientific investigations. On June 1, 2022, M_W 5.9 earthquake occurred in the southern area of the Longmenshan fault zone. This event also happened at the south end of the Dayi seismic gap and is the largest earthquake that has occurred in this seismic gap since the 1970 M 6.2 event. The slip-distribution model constrained by the seismic waveforms suggests a thrust-dominated faulting mechanism. The main slip occurs at a depth of ～14 ?km, and the cumulative energy is released in the first 6 ?s. The variations of Coulomb stress caused by the mainshock show a positive change in the southwest area of the Dayi seismic gap, indicating possible activation of future earthquakes. In addition, we emphasize the importance of rapid estimation of deformation for near-field hazard delineation, especially when interferometric radar fails to image coseismic deformation in a high relief terrain.     

Aftershocks of the San Marcos earthquake of April 25, 1989 (M S =6.9) and some implications for the Acapulco-San Marcos,Mexico, seismic potential

Aftershock activity following the April 25, 1989 (M _S =6.9) earthquake near San Marcos, Guerrero, Mexico, was monitored by a temporary network installed twelve hours after the mainshock and remaining in operation for one week. Of the 350 events recorded by this temporary array, 103 were selected for further analysis in order to determine spatial characteristics of the aftershock activity. An aftershock area of approximately 780 km² is delimited by the best quality locations. The area of highest aftershock density lies inside an area delimited by the aftershocks of the latest large event in the region in 1957 (M _S =7.5) and it partially overlaps the zone of maximum intensity of the earlier 1907 (M _S =7.7) shock. Aftershocks also appear to cluster close to the mainshock hypocenter. This clustering agrees with the zone of maximum slip during the mainshock, as previously determined from strong motion records. A low angle Benioff zone is defined by the aftershock hypocenters with a slight tendency for the slab to follow a subhorizontal trajectory after a 110 km distance from the trench axis, a feature which has been observed in the neighboring Guerrero Gap. A composite focal mechanism for events close to the mainshock which also coincides with the zone of largest aftershock density, indicates a thrust fault similar to the mainshock fault plane solution.The San Marcos event took place in an area which could be considered as a mature seismic gap. Due to the manner in which strain release has been observed to previously occur, the occurrence of a major event, overlapping both the neighboring Guerrero Gap and the San Marcos Gap segments of the Mexican thrust, cannot be overlooked.     

On poundings of a seismically isolated building with adjacent structures during strong earthquakes

This paper presents selected indicative results from an extensive parametric investigation that has been performed in order to assess the effects of potential earthquake‐induced poundings on the overall dynamic response of seismically isolated buildings. In particular, a seismically isolated building and its adjacent fixed‐supported buildings are subjected to various earthquake excitations that induce structural impact among the buildings in series. The results indicate that the seismically isolated building may hit against the adjacent buildings at the upper floor levels before the occurrence of any pounding at the isolation level with the surrounding moat wall. The severity of the impact depends on the dynamic properties of the adjacent buildings, in combination with the earthquake characteristics. Copyright © 2009 John Wiley & Sons, Ltd.     

Community Development Finance Institutions (CDFIs): Geographies of financial inclusion in the US and UK

The financial exclusion of enterprise is a concept that has been largely neglected by economic geographers. This is surprising given the attention dedicated to personal financial exclusion and alternative sources of finance. This paper compares financial inclusion policies in deprived areas of the United States (US) and United Kingdom (UK) through the example of Community Development Finance Institutions (CDFIs). CDFIs help overcome financial exclusion by providing local sources of loan finance to micro, small-and-medium-sized enterprises and social enterprises. Drawing upon interviews with key actors within the CDFI sector in the US and UK respectively, the paper aims to compare the CDFI landscape across the US and UK through the provision of finance for enterprise. This is in order to understand the geographies of finance that are being created by such alternative financial institutions thereby contributing to financial inclusion debates. The research concludes that although CDFIs do provide an important source of finance to excluded enterprises, policy initiatives have created uneven geographical coverage and market gaps leaving marked spaces of financial exclusion.     

New dynamics of rent gap formation in New York City rent-regulated housing: privatization,financialization, and uneven development

ABSTRACT

To explain newfound investor interest in rent-regulated multifamily housing in New York City since 2001, this paper analyzes the transformation in ownership and management of the Riverton Houses, a large rent-regulated housing complex in northern Manhattan. The paper finds new dynamics of rent gap formation at work; rather than depressed capitalized rent attracting investment, increasing potential rent provides a new mechanism for opening rent gaps. The Riverton Houses case shows how three factors increase potentials rents: 1) changes in rent control law that provide new avenues to increase rents, 2) new financial actors and institutions that have higher expectations for risk and return, and 3) longer-term processes of uneven development at the urban scale. Altered rent gap dynamics under processes of privatization, financialization, and uneven urban development complicate the geography of reinvestment beyond a reinvested core and gentrifying periphery. Instead, the urban frontier is drawn recursively within urban space.     

Along-Channel Winds in Howe Sound: Climatological Analysis and Case Studies

This paper examines along-channel winds within Howe Sound, British Columbia, Canada, that occur from both the interior plateau out toward the coast as outflows and from the coast inland as inflows. First, the relationships between along-channel winds and pressure, temperature, and humidity are explored in Howe Sound–Cheakamus Valley. The pressure gradients between Pam Rocks and Squamish and Pam Rocks and Pemberton have the strongest correlations with outflow strength and that between Pam Rocks and Squamish has the strongest correlation with inflow strength. Outflows (inflows) have lower (higher) temperatures and dew point temperatures, except for the inflows in summer, which have lower dewpoint temperatures than the overall mean. Second, two case studies of outflow events are presented and described during the period of intensive observations prior to and during the Vancouver 2010 Winter Olympics. The January 2010 outflow event is caused by a zone of strong across-barrier mean sea level pressure gradient. The pressure gradient is formed behind an Arctic front that moved southward across Howe Sound. The February 2010 outflow event is caused by an approaching sea level low pressure centre from the Pacific that formed a northeast–southwest mean sea level pressure gradient across southern British Columbia. In the January case, the outflow layer is about 1.5?km deep, while it is shallower in the February case. Only the January outflow case exhibits hydraulic behaviour.     

城区渗流场中建筑物间缝隙有限元简化分析方法

为解决城区渗流场中缝隙多、区域的大尺度与物体的小尺寸相差了几个数量级，有限元分析上存在的困难，根据缝隙流动的解析解，经适当地简化，将缝隙附近的渗流场分为缝外区和缝内区两部分，将缝外区流动简化为一个半径为半缝宽的井流，缝内区流动简化为一个均匀流。引入附加阻力系数，考虑缝隙出入口附近的由于过水断面突然变化而引的局部水头损失，并得到附加阻力系数的表达式。利用该式，结合渗流场中井点水头的修正公式，得到了能有效模拟渗流场中建筑物间缝隙的修正线单元公式。利用该线单元编制了相关程序模拟城区渗流场中的缝隙，使得缝隙出入口处的网格尺寸为缝隙两边的建筑物边长1/3～1/4时就能得到较为准确的结果，避免了区域性渗流场中小尺寸物体的网格划分问题，通过算例验证了该公式的精度和边界适应性。     

组合岩样破裂孕育过程中应变场的动态变化特征

利用花岗岩和砂岩拼合样品,进行双轴加压单面直剪试验,结果表明,对于力学性质差异很大的两种岩石的拼合岩样,破裂孕育过程中岩样上的应变是不均匀的,有的地方很高,有的地方很低。在大破裂发生前,应变在一些点沿原趋势加速上升或下降,在一些点则与原趋势相反,转而下降或上升,还有的点则基本平稳不变。应变场变化的共同特征是：①先出现高应变巾心,接着这个中心沿未来剪切缝从砂岩边缘向拼合岩样中部转移,而原先的高应变中心却逐步变成低应变区——应变空区。②主破裂不是发生在高应变中心,而是在应变空区或高应变中心转变而成的低应变中心处,直至主破裂发生。③微破裂和宏观破裂都由砂岩向花岗岩方向发展。     

孕震空区和逼近地震在台湾地震中的应用

本文应用陆远忠等人提出的孕震空区和逼近地震方法 ,分析了台湾及其东部海域所有资料较完整的 6 0级以上的地震。结果表明该区普遍存在孕震空区和逼近地震。在判定是否为孕震空区时 ,采用同样的三个标志。用所得到的数据计算经验公式。最后得出 5点初步结论