This paper presents the second generation of Minnesota Accelerated Loading Facility (Minne-ALF-2), a laboratory-based loading pavement test stand that simulates the passage of heavy wheel loads moving over a small full-scale pavement test strip. It is shown that Minne-ALF-2 can provide important information related to long-term performance of dowel joints of concrete pavements, as well as useful information which may lead to a better understanding of the mechanics of joints in concrete pavements. The first results of the ongoing test program are also presented in the paper. This initial study of joint behavior during loading and unloading of a joint with hollow dowels reveals an interesting pattern: deflections in the unloading path are different from the deflections at the loading path. It was also found that the residual differential deflections remain after the first loading and unloading cycle. Available finite element models for rigid pavements do not explain these effects. Hence, advanced models of PCC joints explaining the observed above phenomenon are needed for a better understanding of the joint behavior and joint design optimization.
The chemical structure of natural organic matter (NOM) is known to influence its removal during coagulation, yet the underlying molecular-scale mechanisms remain elusive. This has limited the rational design of advanced water treatment processes. Here, we reveal a previously overlooked mechanism, the cation-π interaction, as a key driver for the efficient removal of aromatic organic matter. Using model compounds with and without a benzene ring (benzoate/phthalate vs acetate), we demonstrate that the benzene ring is not merely a passive scaffold but an active participant in coagulation. It acts as an initial anchor, attracting trivalent metal ions via strong cation-π interactions. This initial attraction then facilitates a more stable, secondary binding as functional groups (e.g., -COOH and -OH) on the ring chelate with the metal ions, ultimately promoting floc growth. This dual-binding mechanism, supported by spectroscopic and microscopic evidence, explains how the presence of a benzene ring participates in metal ion hydrolysis and floc formation, leading to significantly improved coagulation performance. This finding highlights the critical role of aromatic structures in the coagulation process and provides a new theoretical foundation for optimizing coagulants to achieve the selective and efficient removal of specific aromatic pollutants.
The current situation of microseismic monitoring at home and abroad is not optimistic. The principles, data acquisition, data processing, and intepretation of many monitoring methods are far from the requirements of microseismic monitoring characteristics, and far from the level of analyzing specific microseismicity. We argue that the main technical reason for this situation is still the lack of understanding of microseismic characteristics and the corresponding monitoring characteristics, so that the development and application of microseismic monitoring are not based on strict seismology, geology, rock mechanics, a large number of reliable experiments, and mathematical statistics. Microseismic monitoring is even more difficult than monitoring stealth aircraft and navigators, in which the target and detector are separated by fluid, and there is always some way to test them. This paper first summarizes the characteristics of microseismic and its monitoring. Based on this, as well as the most basic requirements of seismometry, various monitoring methods are discussed, including their applicable conditions, limitations and development prospects. This discussion shows that the development and application of microseismic monitoring have to be based on the reality of low signal-to-noise ratio, even after avoiding strong noise sources as much as possible during data acquisition and effectively denoising during processing. This paper then reports that in the past two to three years, following the review ("Microseismic and its monitoring") in January 2023, our Vector Scanning (VS) for microseismic ground monitoring has been greatly improved, including an in-depth understanding of the VS principles, the refinement of the conditions necessary for the success of the VS application with a high probability, and their quantitative integration in the VS automated process of data processing and interpretation. A large number of cases are available for mathematical statistics, which provide a basis for analyzing the details of microseismicity. Finally, we describe the specific morphology of the Stimulated Rock Volume (SRV) induced by fracturing, the relationship between the corresponding deformation and the stress fields (equivalent microseismic focal mechanism), and the effect of production measures such as pump shutdown. The necessary conditions, monitoring output patterns, some analyses and questions described here also provide a basis for the test of the microseismic monitoring.
Crystallization sequence of Al 2 SiO 5 polymorphs in a sample from an early Paleozoic metamorphic unit (Silgará Schist) in the Northern Andes of Colombia is interpreted to be kyanite → andalusite → sillimanite (fibrolite), the least common sequence in samples where the three polymorphs coexist. This interpreted sequence has important implications in terms of tectonic evolution of the pre-Cretaceous crystalline core of the Northern Andes. Like interpretations in other geological provinces, the sequence kyanite → andalusite → sillimanite observed here is linked to polymetamorphism during two unrelated tectonic episodes. Kyanite grew during a prograde early Paleozoic Barrovian metamorphic event at pressures between 7 and 9 kbar. During a late Triassic–Jurassic overprinting low-pressure event, andalusite + sillimanite formed ( P < 3.8 kbar). The Barrovian Silgará Schist sequence shows staurolite appearing almost coincidently with garnet and before kyanite. Kyanite crystallized in a chlorite-free assemblage following a prograde trajectory and persisted metastably during the overprinting event.
