Search

Creeping landslides may fail catastrophically, posing significant threats to infrastructure and lives. Landslides weaken over time through rock mass damage processes that may occur by steady‐state creep or transient accelerations of slip, called creep bursts. Creep bursts may control landslide stability by inducing short‐term damage and strain localization. This study focuses on the Åknes landslide in Norway, which moves up to 6 cm per year and could potentially trigger a large tsunami in the fjord below. An 11‐year data set is compiled and analyzed, including kinematic, seismic, and hydrogeological data acquired at the landslide surface and in a series of boreholes. An annual average of two creep bursts with millimeter amplitude has been recorded within the shear zone in each borehole, accounting for approximately 11% of the total displacement. Creep bursts detected simultaneously in multiple boreholes are preceded by increased seismic activity and rising water pressure. However, most creep bursts are observed in only one or a few boreholes. These bursts often happen during seasonal high and low groundwater levels in autumn and spring, respectively, correlating with local peaks in water pressure. No such correlation is observed during summer. We propose that creep bursts can have different causes and hypothesize that rock degradation leads to some creep bursts independent of water pressure variations. In contrast, the largest creep bursts are correlated with variations in absolute water pressure or gradients of water pressure within the shear zone. Our findings emphasize the complexity of a dense data set requiring multiple mechanisms to explain creep burst dynamics. Plain Language Summary: Slow‐moving landslides, advancing from millimeters to meters per year, can have strong destruction potential if they fail catastrophically. A landslide sliding plane weakens over time by rock crushing and fracturing. One of these processes is short‐lived movement accelerations that we call creep bursts. Creep bursts may control landslide stability by inducing short‐term damage and the development of a plane that allows the landslide to slide, which may lead to catastrophic failure. This study focuses on the Åknes landslide in Norway, which moves at 6 cm per year and could potentially trigger a great tsunami in the fjord below. Creep bursts with millimeter movements are detected at the landslide's sliding plane. Some creep bursts occur without water pressure changes at the initiation of the motion. These bursts are likely caused by the gradual crushing of the rock mass, independent of water level fluctuations. Conversely, the largest creep bursts are correlated with seasonal variations in groundwater level within the landslide. These larger bursts may be related to an easing of sliding by the absolute or the water pressure gradient. Our data set provides quantitative insights into transient slip accelerations, and these accelerations may be crucial in driving a large‐scale failure of the Åknes landslide. Key Points: We detected creep bursts on the shear zone of the Åknes landslide that accommodated 11% of the total displacementThe largest creep bursts are preceded by increased water pressure and microseismicity in the shear zoneMost of the creep bursts occur randomly over the year without correlation with other environmental parameters [ABSTRACT FROM AUTHOR]

A ruthenium nitrosyl complex of formula [RuII(fluorene(C6)CH2O-terpy)(bipy)(NO)]3+ (AC) in which fluorene(C6) is the 9,9-dihexylfluorene, terpy the 2,2′;6′,2′′-terpyridine, and bipy the 2,2′-bipyridine is presented with its related [RuII(MeO-terpy)(bipy)(NO)]3+ (C) and 9,9-dihexylfluorene 2-hydroxymethylfluorene (A) building blocks. The reference complex C undergoes NO release capabilities under irradiation at λ = 365 nm. The effect of the introduction of the fluorescent A antenna within the resulting AC complex is discussed both experimentally and theoretically. The importance of the encaging parameter defined as φAC·IAC, in which IAC is the quantity of light absorbed by AC and φAC the quantum yield of NO release is evidenced and found to be concentration dependent. The conditions of optimization of the antenna approach to maximize φAC·IAC are discussed. The crystal structure of [RuII(fluorene(C6)CH2O-terpy)(bipy)(NO2)](PF6), the last intermediate in the synthesis of AC is also presented. [ABSTRACT FROM AUTHOR]

Ruthenium nitrosyl (RuNO) complexes continue to attract significant research interest due to several appealing features that make these photoactivatable nitric oxide (NO˙) donors attractive for applications in photoactivated chemotherapy. Interesting examples of molecular candidates capable of delivering cytotoxic concentrations of NO˙ in aqueous media have been discussed. Nevertheless, the question of whether most of these highly polar and relatively large molecules are efficiently incorporated by cells remains largely unanswered. In this paper, we present the synthesis and the chemical, photophysical and photochemical characterization of RuNO complexes functionalized with 17α-ethinylestradiol (EE), a semisynthetic steroidal hormone intended to act as a molecular Trojan horse for the targeted delivery of RuNO complexes. The discussion is centered around two main molecular targets, one containing EE (EE-Phtpy-RuNO) and a reference compound lacking this biological recognition fragment (Phtpy-RuNO). While both complexes displayed similar optical absorption profiles and NO˙ release efficiencies in aqueous media, important differences were found regarding their cellular uptake towards dermal fibroblasts, with EE-Phtpy-RuNO gratifyingly displaying a remarkable 10-fold increase in cellular uptake when compared to Phtpy-RuNO, thus demonstrating the potential drug-targeting capabilities of this biomimetic steroidal conjugate. [ABSTRACT FROM AUTHOR]

The estimation of seismic damages and debris at the urban scale—at a building-by-building level- is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to estimate at the same time the quantity of debris generated per building according to its damage level and the distribution of the debris (extent and height) around buildings. Finally, the lack of comprehensive data on the building stock and the relevant building properties and their taxonomy further increases the complexity of assessing possible earthquake consequences at an urban scale. This paper addresses these challenges and proposes improvements to the assessment of seismic damages and debris from building-level simulations, along with the development of a 3D building model based on satellite images and heterogeneous data. These developments, applied to the city of Beirut, Lebanon, highlight the control of the site effects on the seismic damage's spatial distribution throughout the city and the large volume and extent of debris to be expected in the city for a strong earthquake. [ABSTRACT FROM AUTHOR]

One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl‐substituted terpyridine ligand, and bpy the 2,2'‐bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF‐CC‐TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis‐RuNO2 and bis‐RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one‐photon absorption (OPA) correlates well with the TD‐DFT computations. A spectacular effect is observed at two‐photon absorption (TPA) with a large enhancement of the molecular cross‐section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA‐based drug delivery. [ABSTRACT FROM AUTHOR]

Since the discovery of the numerous physiological roles exhibited by nitric oxide (NO), ruthenium nitrosyl (RuNO) complexes have been regarded as one of the most promising NO donors, stable, well tolerated by the body and capable of releasing NO locally and quantitatively, under light irradiation. This release can be achieved by two-photon absorption (TPA) processes, which allow the irradiation to be performed in the near infrared domain, where light has its maximum depth of penetration in biological tissues. This review provides a short introduction on the biological properties of NO, on RuNO complexes with photo-releasing capabilities, and on the origin of TPA properties in molecules. Then, the RuNO complexes with TPA capabilities are thoroughly discussed either as monometallic or polymetallic species. [ABSTRACT FROM AUTHOR]

The synthesis, crystal structures, and the quadratic nonlinear optical (NLO) response properties of new nickel(II) metal complexes are described. The effect of the metal in the environment of the ligand charge-transfer pathway is investigated experimentally by the electric-field-induced second-harmonic (EFISH) method.

The massive worldwide deglaciation leads to more frequent slope instabilities in mountainous terrains. The physical processes leading to such destabilizations are poorly constrained due to little monitoring of dynamic parameters at the local scale. Here we study a very large slow‐moving landslide (∼0.8 km2), on the flank of Tungnakvíslarjökull glacier in Iceland. Based on a combination of remote sensing images, we monitor the landslide and glacier kinematics over 75 years, with a focus over the period 1999–2019 when rapid glacier wastage has been observed. The landslide accelerates from 2 to 45 m/yr in the 6 years following a sudden increase in glacier mass loss. This acceleration coincides with intense quake activity (Mℓ < 2.8), recorded by a regional seismic network. We show that this seismicity is caused by the landslide sliding on a rough surface. The evolution of the quake magnitudes suggests a progressive segmentation of the landslide mass during its acceleration. Plain Language Summary: Glacier‐retreat may lead to a destabilization of adjacent slopes that can evolve into large landslides. The time‐scales, as well as the controlling factors of the landslide response to this glacier retreat are poorly known, due to few observations of landslide dynamics in the vicinity of glaciers over the long term. To fill this gap, we document the dynamics of a large landslide in Iceland, developing on the flank of Tungnakvíslarjökull glacier, that underwent strong retreat after 1994. Based on aerial images since 1945 and satellite images since 1987, we calculate the motion of the landslide through time. We show that the landslide accelerated from 2 to 45 m/yr in the 6 years following the onset of glacier retreat. This acceleration coincides with earthquakes of small magnitudes (Mℓ < 2.8), produced by the landslide motion. Their analysis suggests that the landslide mass is progressively fragmented during the acceleration. This study opens interesting perspectives for landslide studies by combining seismic records from regional networks and 3D motions from satellites. Key Points: We monitor the dynamics of a very large slow‐moving landslide over 75 years, developing on the flank of a glaciated valleyThe landslide kinematics is strongly controlled by the glacier retreat, and produce seismicity correlated with the landslide velocityThe acceleration is linked with progressive segmentation of the landslide mass [ABSTRACT FROM AUTHOR]