Early Detection of Structural Damage in UHPFRC Structures through the Combination of Acoustic Emission and ultrasonic stress wave monitoring

Ultra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC) offers several advantages compared to concrete, notably due to the strain hardening behavior under tensile actions. Structures made of this composite material are lightweight and highly durable, thanks to the UHPFRC waterproofing quality. Nonetheless, the tensile behavior leads to a different cracking pattern than conventional concrete and is not fully understood yet. This paper presents a combined approach using both passive ultrasonic (US) stress wave (or acoustic emission) and active US stress wave monitoring to localize and quantify damage progression in a full-scale UHPFRC beam during experimental load testing. The proposed monitoring approach involves 24 US transducers that are embedded randomly throughout a 4.2meter-long laboratory UHPFRC T-beam. Continuous monitoring enabled accurate localization of US stress sources caused by loading-induced cracking as well as from pulses generated by the embedded US transducers. This study shows that it is possible to predict the location and shape of the macro-crack that is linked to structural failure early on, i.e., just after the end of the elastic domain. This combined approach opens new possibilities to monitor the structural behavior and detect damage on UHPFRC structures before they affect the structural behavior in terms of deflection and strain

Bio- and chronostratigraphy of the Middle Triassic Reifling Formation of the westernmost Northern Calcareous Alps

New finds of fossils including bivalves, ammonoids, brachiopods and palynomorphs from the Middle Triassic Reifling Formation significantly improve the age assignment for this unit in Liechtenstein and Vorarlberg. The lower part of the Reifling Formation is tentatively referred to the Late Anisian Paraceratites trinodosus Zone and somewhat older levels, whereas the uppermost part reaches the Ladinian Protrachyceras archelaus Zone (ammonoid zonation). The Middle Triassic successions of the study area are correlated with the coeval South Alpine reference section at Bagolino (Brescian Prealps), which also bears the Ladinian GSSP. The comparison shows that the Reifling Formation in the study area is age-equivalent with the South Alpine Prezzo Limestone and the Buchenstein Formation. A volcanoclastic layer in the upper part of the Reifling Formation at Flexenpass yields a U-Pb zircon age of 239.3 +/- 0.2 Ma. This value is slightly older than previously published minimum ages from equivalent horizons in the Southern Alps; the difference is thought to be mainly due to improved pre-treatment of zircons (annealing/chemical abrasion), which significantly reduces the effects of Pb loss. The new radio-isotope age further constrains the stratigraphical age of the Reifling Formation and supports the proposed biostratigraphy-based correlation of Middle Triassic successions in the Eastern and Southern Alp

A new early Smithian ammonoid fauna from the Salt Range (Pakistan)

Recent extensive investigations in the Salt Range (Pakistan) yielded abundant, well-preserved ammonoid faunas of earliest to latest Smithian age that provided the basis for a major revision of Smithian ammonoid taxonomy and for the establishment of a high-resolution biostratigraphic sequence. Here, an additional new ammonoid fauna of typical early Smithian affinity from the uppermost part of the Ceratite Sandstone of the Nammal Gorge section is described. The new fauna, termed Euflemingites cirratus beds, is bracketed between the underlying early Smithian "Flemingites flemingianus beds”, here renamed Clypeoceras superbum beds, and the overlying middle Smithian Brayardites compressus beds. Comparison with a recently published high-resolution biochronological scheme for the Smithian of the NIM (northern Indian Margin) based on the Salt Range, Spiti (Himachal Pradesh, northern India) and Tulong (South Tibet) basins shows that the Euflemigites cirratus fauna correlates with the Dieneroceras beds from Spiti based on the common occurrence of the ammonoid species Kraffticeras pseudoplanulatum. The trans-panthalassic biogeographical distribution of Euflemingites cirratus allows correlating the new ammonoid fauna with part of the Meekoceras gracilitatis ammonoid zone of western USA. Three new species (Kashmirites weisserti, Arctoceras schalteggeri and Vercherites wyleri) are describe

Towards 99mTc- and Re-based multifunctional silica platforms for theranostic applications

Taking advantage of the radiation properties of 99mTc and 186/188Re and the photophysical characteristics of the {M(CO)3}+ moiety (M = Re), we developed a multifunctional silica platform with the theranostic pair 99mTc/Re with high potential for (nano)medical applications. Starting with a general screening to evaluate the most suitable mesoporous silica construct and the development of appropriate chelate systems, multifunctional mesoporous silica microparticles (SBA-15) were synthesized. These particles act as a model towards the synthesis of the corresponding nanoconstructs. The particles can be modified at the external surface with a targeting function and labeled with the {M(CO)3}+ moiety (M = 99mTc, Re) at the pore surface. Thus, a silica platform is realized, whose bioprofile is not altered by the loaded modalities. The described synthetic procedures can be applied to establish a target-specific theranostic nanoplatform, which enables the combination of fluorescence and radio imaging, with the possibility of radio- and chemotherapy

Early detection of structural damage in UHPFRC structures through the combination of acoustic emission and ultrasonic stress wave monitoring

peer reviewedUltra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC) offers several advantages compared to concrete, notably due to the strain hardening behavior under tensile actions. Structures made of this composite material are lightweight and highly durable, thanks to the UHPFRC waterproofing quality. Nonetheless, the tensile behavior leads to a different cracking pattern than conventional concrete and is not fully understood yet. This paper presents a combined approach using both passive ultrasonic (US) stress wave (or acoustic emission) and active US stress wave monitoring to localize and quantify damage progression in a full-scale UHPFRC beam during experimental load testing. The proposed monitoring approach involves 24 US transducers that are embedded randomly throughout a 4.2meter-long laboratory UHPFRC T-beam. Continuous monitoring enabled accurate localization of US stress sources caused by loading-induced cracking as well as from pulses generated by the embedded US transducers. This study shows that it is possible to predict the location and shape of the macro-crack that is linked to structural failure early on, i.e., just after the end of the elastic domain. This combined approach opens new possibilities to monitor the structural behavior and detect damage on UHPFRC structures before they affect the structural behavior in terms of deflection and strain

Dienerian (Early Triassic) ammonoids from Spiti, Himachal Pradesh, India

Introduction The Northern Indian Margin is known since the end of the 19th century as a classical region for the study of Early Triassic ammonoid faunas. In a companion work (Ware et al. 2018), Dienerian ammonoids of the Salt Range (Pakistan) were thoroughly revised. A new high resolution biostratigraphical scheme was proposed for the Salt Range and correlation with other recently established biozonations (Tozer 1994 for Arctic Canada; Dagys & Ermakova 1996 for northern Siberia; Shigeta & Zakharov 2009 for Primorye, Russia) was discussed. The Spiti region (Himachal Pradesh, India) is a classical area for studying Early Triassic ammonoids of the Northern Indian Margin. Ammonites were described in two monographs first by Diener (1897) followed by von Krafft & Diener (1909). These two pioneering works unfortunately lack a detailed stratigraphic context, and many new species are only indicated as coming from the ‘lower division of the lower Trias’, a very vague indication, which does not provide the basis for an accurate and precise biozonation. Until very recently, no other papers concerning Early Triassic ammonoids from Spiti have been published. In the mid-1990s, Leopold Krystyn started the investigation of various sections in Spiti, which led him to propose a section near Mud as a Global Boundary Stratotype Section and Point (GSSP) candidate for the Induan–Olenekian boundary (equivalent to the Dienerian–Smithian boundary; Krystyn et al. 2007a, b). Only a few ammonoids were illustrated and described in these studies, as the focus was on the boundary interval. After the work in India by Krystyn et al. (2007a,b) the research group at the University of Z€urich conducted two intensive seasons of fieldwork in 2008 and 2009. This lead to the discovery of typical Smithian ammonoids below the boundary (Br€uhwiler et al. 2010) proposed by Krystyn et al. (2007a,b), thus questioning the proposed definition of the Induan–Olenekian boundary (see the foreword, Ware & Bucher 2018a for details). Recently, Br€uhwiler et al. (2012) revised and described the middle and upper Smithian ammonoids from Spiti district. The present work focuses on the abundant and fairly well preserved ammonoid faunas from a detailed bedrock controlled sampling in the Mud, Guling and Lalung areas of the Spiti District. The great similarity with the Salt Range, Pakistan, allows the authors to establish a detailed and laterally reproducible but informal biozonation for the Dienerian of the Northern Indian Margin. Based on these results, a formal biozonation for the Northern Indian Margin was constructed by Ware et al (2015)

Towards 99mTc- and Re-Based Multifunctional Silica Platforms for Theranostic Applications

Taking advantage of the radiation properties of 99mTc and 186/188Re and the photophysical characteristics of the {M(CO)3}+ moiety (M = Re), we developed a multifunctional silica platform with the theranostic pair 99mTc/Re with high potential for (nano)medical applications. Starting with a general screening to evaluate the most suitable mesoporous silica construct and the development of appropriate chelate systems, multifunctional mesoporous silica microparticles (SBA-15) were synthesized. These particles act as a model towards the synthesis of the corresponding nanoconstructs. The particles can be modified at the external surface with a targeting function and labeled with the {M(CO)3}+ moiety (M = 99mTc, Re) at the pore surface. Thus, a silica platform is realized, whose bioprofile is not altered by the loaded modalities. The described synthetic procedures can be applied to establish a target-specific theranostic nanoplatform, which enables the combination of fluorescence and radio imaging, with the possibility of radio- and chemotherapy

Spectral-based analysis of thin film luminescent solar concentrators

We present a method to evaluate the parameters defining the efficiency of luminescent solar concentrators (LSCs). The light harvesting and self-absorption properties of thin film LSCs on glass substrates are determined by optical spectroscopy and the resulting optical efficiency is consistent with the directly measured photon flux gain